Throttle for speed, or stick for speed?

[AlexL]

during all my PPL training, the Mantra of 'Stick for speed' and 'Throttle for height' was taught. I'm aware that there is in fact a couple between the stick and throttle and in reality co-ordination of both are required, but I think its more about the way you think about it, than the actaul effect of the controls.

However I'm just reading Thom 5 for my IMC and all the way through this the philosophy appears to have changed to "Stick for height / glideslope / flightpath", and "Throttle for speed"
Is there any particular reason for this change in thinking? or is it authors and instructors preference? What gets taught on IR's and to commercial airline pilots? Or given that its really a co-ordination of the controls thats required is it really down to personal preference?

[kookabat]

Think this is one that's been argued since the Wright Brothers. Depends on who you talk to really... tend to go with the co-ordination model myself.

[englishal]

Its becasue you normally fly the ILS (or any IAP) at a much higher speed than when you are on a visual approach. I normally aim for 100kts on an IAP in a SEP. Its all to do with where you are on the drag curve.

EA

[Shaggy Sheep Driver]

I don't really think it matters. Like riding a bike, you don't analyze it - you just do what you need to do to make the aeroplane do what you want. If you are lucky enough to fly a Chipmunk, you don't worry about moving the stick - it's all done by thought processes anyway. :D

SSD

[AlexL]

ahh, Englishal , I think I can see that. So at low speed close to the back of the drag curve, putting the nose down is a much more responsive way to gain speed? and at higher speeds with higher energy and less drag, raising the nose, say, will just alter flightpath and not have much effect on speed? Is that it? Kinda makes sense to me if thats the case.

[englishal]

Yep, thats about it :D

[greeners]

John Farley's articles in Flyer magazine addressed this at some length. With a Jet Provost very low and slow on short final, he asked the QFI to demonstrate how lowering the nose would get the speed back. Needless to say, the only thing to do in that situation is to put the power on, controlling speed with throttle. I recall John wrote that only the US Navy and GA used 'attitude for speed' on landing, with all others using 'throttle for speed'.

Initially at our school we teach attitude for speed; when climbing at full power, or descending in the glide, there is obviously no option. However, we 'flick the switch' once the student has reached a designated 500 foot point and revert to 'point and shoot', using attitude to point at a consistent spot on the runway and throttle to manage speed, and find that most people find ths an easier approach to make consistent early landings.

After a while people stop thinking about which control affects what (as they are of course inter-related) and 'use the force, Luke', but you can't start out like that!

[Miserlou]

I started out as a glider pilot so I know that it's stick for speed/throttle for height.

I think it's poorly explained so that one gets the impression that things are not done the same way for IMC.

The trick, espacially for instrument flying, is to have the aircraft trimmed to the correct speed. Thus, if one starts going a little low on the glidepath, I'll maintain the glide with a pitch correction and add power until there is no longer a stick force, then reduce the power again to a little more than I had initially. I'll never retrim.

[IO540]

TRIM for the desired speed is the best kept secret in flying :O

Once you know that the trim determines the speed, the workload of flying a plane falls drastically. None of the PPL instructors I flew with ever told me that though. It was only an IR one I had for the IMCR that seemed to know it.

[Confabulous]

Trim trim, trim, trim...

And keep triming.

See:

John Denker's 'See How It Flies' (http://www.av8n.com/how/htm/aoa.html)

Stick & Rudder (http://www.amazon.co.uk/exec/obidos/ASIN/0070362408/qid=1108068336/sr=1-1/ref=sr_1_27_1/202-9203302-1907828)

[Final 3 Greens]

Miserlou

Unless I misread your post, your technique is to adjust the rate of descent with the stick and then use the power to safeguard the airspeed ;)

[Croqueteer]

For a constant glideslope, visual or instrument, if you are above it you reduce power then lower the nose to retain airspeed, if you are below it, you add power and raise the nose to maintain airspeed and regain the slope. that seems to add up to power for rate of descent, attitude for airspeed. Power plus attitude equals performance.

[BitMoreRightRudder]

I was always taught stick for speed, power for rate of descent during VFR training. That motto works well with the constant aiming point method.

In IFR it's all change - now I'm told stick for ROD, power for speed. I'm finding that a high speed ILS in a twin requires very subtle applications of the new formula!

Of course the real trick in VFR is to set the power on base prior to descent and then not touch the throttle until at/very near the threshold - in my experience only works with a light wind and an empty circuit, or maybe thats just me! :{

[swh]

AlexL,

Instrument flying is just like VFR flying, except for having the outside horizon, you have an artifical one.

Instrument flying is about setting attitudes..and achieving a desired performance.

So for example in a descent on an ILS you will have a target pitch attitude, target rate of descent...maybe 600 fpm on an ILS, and a target airspeed. You will need to adjust you pitch attitude to the desired one, and adjust your power for the desired airspeed.

So for any phase of flight you should know the target pitch attitude, and power setting, if you set these initially, you can then adjust to refine fine tune your performance. Just like you do when flying VFR.



:ok:

[Miserlou]

F3G.
Perhaps, not sufficiently clear. Not trying to get into deep discussion I tried to keep it short.
Very minor corrections to glidepath made with the stick. Any trend, that is a correction which continues to be required, corrected by power; these are very small, needle-width corrections I'm refering to here.
For the ILS it is more critical to maintain the flightpath so the pitch correction is only temporary to avoid the slight time delay and any further deviation. The causes and effects do overlap a little.

The trim setting remains the same.

[Final 3 Greens]

Miserlou

I was being a little naughty :}

[Whopity]

In a steep turn you maintain level with elevator and maintain speed with throttle

S & L you maintain a level attitude with elevator and control speed with throttle

why should a powered approach be any different?

[ChrisVJ]

Marvelous.
After100 years of airplanes we still don't have a a universal method of handling one of the more dangerous phases of flight.

One can certainly understand the differences that may be required to handle heavies, or even just jets, given their mass and the spool up time etc however it seems there is no clear picture even for SEP GA.

When I was taught (40 yrs ago) there was absolutely no doubt. Attitude for speed and throttle for descent was universal and the only way to go. Like a lot of simple things it seems to have been forgotten in a plethora of theories and complications. When I started again 5 years ago I was astonished and dismayed that my instructor told me to "hold the nose up with the yoke" all the way through the climb out instead of trimming for speed and no control pressure. I have even seendiscussions of pilots "Holding the nose down with stick on approach so you can just relax the pressure to flare" which seems to me to be the epitome of poor practice. Perfectly barmy.

(As an aside. If you get slow on approach the AOA increases. Lowering the nose not only speeds the plane up quickly but also temporarily relieves the wing load and lowers the AOA. (Adding throttle doesn't do that until the air speed rises. In fact on some planes the chage intrim actually increase the AOA with throttle. If you are near critical AOA that might make a difference.)

[Confabulous]

Couldn't agree more Chris.

Once again I highly recommend either Wolfgang Langeweische's 'Stick & Rudder' and John Denker's 'See How It Flies' (http://www.av8n.com/how/).

'See How it Flies' is free online, and covers much the same material as 'Stick & Rudder'. A few hours on that site and you'll have gained a few hundred (or thousand) hours worth of flying experience.

Conf

[AlexL]

Thanks for the replies. I've always been happy with "stick for speed", but it was reading the IMC book that added the confusion. I've got 'Stick and Rudder' for christmas, so I just need to get round to reading it now!

[Miserlou]

That's very interesting Whopity.
Why do the laws of aerodynamics change when you bank then?

I'd rather understood that if you have a constant bank angle, pitch attitude and speed but found yourself descending, you needed more power. If you already have full power then there is only one option left...lower the nose a little.

[Algirdas]

Miserlou,
If you run out of power, you can decrease your angle of bank.
Lowering the nose would put you into a descending turn.
A

[Whopity]

Miserlou,

they don't.

Whatever you do, Attitude + Power = Performance; if you change either attitude or power you will need to change the other inversely to maintain the performance. Which you do first, is a matter of choice however, instrument lag and aircraft inertia may determine that one way is more effective than the other in certain circumstances.


When climbing and descening at a fixed power then attitude is the only way to control airspeed, which of course should always be trimmed, if you instructor tells you otherwise change him for a better one.

The object on an approach is to fly a line of constant bearing from the point where you roll out on final to the touchdown point. Personally, I find it much easier to hold that bearing optically than fishing arround with the attitude and descending in a series of steps. If the attitude and power remain constant only the met will change things.

[Keef]

Greeners describes the way I was taught, and it works for me. "Use the force"! I don't really think about it in VFR - just look at the spot on the runway where I want to crash, and the aeroplane goes there.

For IFR, I had an outstanding instructor, and he taught me to fly "by the numbers". I know, for my aircraft, the power settings that will achieve S&L and the normal ROC and ROD. Set those, trim (trim) and the aeroplane does what you want. For minor adjustments, it's usually the yoke for me - the power stays in the right place.

I suppose it would be very different in an aircraft with widely varying weights, but with the standard load in the Arrow, that works fine.

[slim_slag]

keef,

For minor adjustments, it's usually the yoke for me - the power stays in the right place.

Yes, fly the numbers, but for small adjustments (like what you should be doing on an ILS) have you tried just making very small adjustments to your pitch using the trim wheel to stay on the glideslope? That's small adjustments by the way. Its actually a lot easier and more sensitive than using the yoke. Did I mention only using this technique for small adjustments to pitch?

Use the rudder for small adjustments when flying the localiser. Apparently this heretic approach also works nicely on bigger turbine powered stuff, but that's only what I've been told by others :ok:

[Miserlou]

Algirdas,
You could (and would) but maintaining the bank angle proves that Whopity's explanation is false.. Therefore, bank angle-constant, power-constant, speed constant. The only thing left to control the speed, which would be reducing if you maintain altitude, is adjust the attitude.

Whopity,
Attitude+power=performance is an old cliche. Please supply us with the correct mathematical equation showing the inverse proportionality.

In your wriggling you've just just introduced a fixed power setting where no fixed power setting belongs. The required constants for an approach are airspeed and flightpath. Manifold pressure or torque will change due to atmospherics and the required power because of the wind. You can maintain the glidepath with the stick, just as you would a constant height, but I reckon any more than a needle-width, as I said earlier, is more likely a trend or change in conditions requiring a power change.

If you want to discuss which one should do first then we'll have to come right back to perhaps one knot above the stall and apply full power, whilst holding everything else constant (and at a safe height). It's a good technique to get a clean entry into a spin or flick!

[Final 3 Greens]

If you want to discuss which one should do first then we'll have to come right back to perhaps one knot above the stall and apply full power, whilst holding everything else constant (and at a safe height). It's a good technique to get a clean entry into a spin or flick! Which is a good argument for respecting Vs1.3 as an approahc speed.

[bookworm]

One can certainly understand the differences that may be required to handle heavies, or even just jets, given their mass and the spool up time etc however it seems there is no clear picture even for SEP GA.

That's probably because "SEP GA" covers a very broad range of types that can be flown at a broad range of speeds.

1) Operating at or close to the bottom of the drag curve, it's not possible to make sustained corrections reliably with pitch. Whether you pull or push, your glideslope gets steeper. As you move away from the bottom of the drag curve, the trade off between speed between glideslope changes gearing. A substantial change in glideslope adjusted by pitch causes only a small speed variation.

2) At the same time, as speed increases, the phugoid period increases in proportion. When you add thrust at a constant AOA, the primary effect of the thrust increase is a speed increase -- equilibrium isn't instant, and it takes some time for that speed increase to get turned into a change in glideslope at the original speed. The time required for it to "sort itself out" is proportional to the phugoid period.

3) Faster aircraft tend to be powered by more complex powerplants. While the turbine with a substantial spool time is an extreme, turbocharging and even constant speed units cause short delays between throttle movement and response. That makes it harder to make fine adjustments with power.

All of those make this game horses-for-courses.
The technique that works best at visual approach speeds in a C152 and the technique that works best for a turbo-charged Bonanza flying an ILS approach may well be different.

FWIW, the best mnemonic I even learned for the ILS was DFWTP: Don't ...er... Fiddle With The Power.

[pablo]

Hi folks!

Everyone knows pitch controls power, and speed controls altitude!:}

See here! (http://www.avweb.com/news/columns/182148-1.html) :E

Regards!

[Classic]

Think about it in energy terms.

If you are slow or below the glidepath or both, you need to ADD energy, ie add power and/or raise the nose attitude. Even in jets, the approach power is set to give sufficient responsiveness to power changes, so in the first instance I would always adjust power if slow.

Would those advocating the stick for speed method push the stick forward if low and slow? Of course not, so why confuse a student with that technique?

Use the same technique you would use S+L, why change it?

As for slim slag's idea of rudder to maintain the localiser, you'd fail an IRT for using that technique for several reasons: Associated roll, discomfort for pax, Flight Director problems, destabilising drag increase.....

[DFC]

Atitude + Power = Performance.

Pitch up - speed decreases - lift decreases
Pitch down - speed increases - lift increases

Increase power - speed increases - lift increases - aircraft pitch moments change
Decrease power - speed decreases - lift decreases - aircraft pitch moments change

Everything is interlinked.

Point the aircraft where you want to go (attitude) and adjust the power to give the required speed (power) can provide very stable approaches thus making it easy to determine "impact point".

Making an approach that will hit the numbers can be done as a constant speed but a number of different power settings -

No power - a glide approach - this is the steepest approach you can do without gaining further speed above the chosen speed (ignoring side-slip etc)

Full power - this is where you hit the numbers in the climb from below (theoretical only) :)

Just less than cruise power (for that speed) - where the approach path is almost level. Nice for that carrier landing!

Taking the extremes -

If the glide approach is putting you long (beyond the numbers) you have no choice but to accept that if you lower the nose - the speed will increase and you will hit the numbers but for a real approach you have to wash off that extra speed.

If the (theroetical) full power climb is going to reach the level of the imaginary runway beyond the numbers - you have no choice but to accept that because raising the nose further will reduce the speed below the chosen speed.

So each approach will depending on how steep the desired approach path is, have an aiming point and a power setting.

Moving the aiming point will have an effect on the speed - changing the speed vector will simply get you to the aiming point faster.

Drag slows us down and works to oppose our efforts at travelling towards our aiming point - the force that prevents us slowing down is thrust.

If you want to make an approach at say 70Kt to a particular aiming point - you have two choices - make a glide approach at 70Kt or use power to maintain 70Kt while making a less steep approach..........the point where the aircraft will hit the runway has not changed and the aircraft is still travelling towards it - but to prevent the aircraft from slowing down on the more shallow approach power is used to maintain the speed.

How one pictures it makes litle difference - It is the total pefromance (Attitude + Power) that counts.

To see this for oneself - try the following flying with a trusted fellow pilot:

Set the aircraft up on a 3deg power approach in the desired configuration and speed and on the glideslope according to ILS or PAPI. Take a marker and mark the windscreen where the touchdown point (abeam the PAPI) is on the window.

Now take the aircraft round again and try various approaches above and below the 3deg but always aiming for that same point (abeam the PAPI). You keep that mark fixed on the aiming point using the stick and get your friend to use the throttle to maintain the speed. See how it works.

Next position the aircraft below the glide and again with your friend using the throttle to maintain speed - move the aim point up towards the horizon and hold it there until established on the 3 deg slope then lower it to the runway aim point. Then do the same from above by putting the aim point before the threshold (all while your friend uses power to maintain speed).

You will find that if you let things get too high, your friend will have the throttle closed because you have the aircraft in the glide attitude - any steeper and you have to accept a higher speed!

Don't try the flying it almost level with high power to the runway in this life! :D

Hope the above ramblings help!

Regards,

DFC

[Miserlou]

Classic,
Perhaps I could remind you of the procedure for recovery from the the stall.
1. Release back pressure on controls.
2. Apply power.

So would you push the stick forward if low and slow? Of course you would or maybe you end up in a hospital bed with a previously mentioned glider pilot.

[Final 3 Greens]

I wouldn't push the stick forward at low level, but I would release the back pressure.

It may just be the form of words, but I perceive a significant difference between the two actions.

[Chimbu chuckles]

One very important part of this discussion that seems missing so far is this.

The thottle = speed dictum is related mostly to jets...particularly heavy jets. This is because they have such relatively high weight and therefore momentum that if you're slow and lower the nose you will just get a huge increase in ROD...long before you get any meaningfull increase in speed. It's fairly similar in very heavy prop aeroplanes too...but mostly jets...with prop aeroplanes, particularly big multi engined ones an increase in power brings about an increase in lift from the accelerated air travelling over the wings and then some acceleration....pour on the coals in a jet and the lift only increases as a buy product of the extra speed....jets are usually approaching to land on the back side of the drag curve which just exacerbates the effect...prop aircraft, particularly little ones are not...to anywhere near the same extent anyway.

So in a jet we trim for a specific attitude and hold speed constant with thrust....a little slow=more thrust...a little fast = less thrust...a little high = lower the nose...a little low = raise it. The very high momentum means that raising or lowering the nose has little effect on speed in the short term. In a jet if I am a little low and increase thrust I'll just go lower faster because I don't have the instant increase in lift you get from increasing power in a typical GA twin/single.

So many techniques filter down to GA from Airlines and are assumed to be better simply because that's the way the big boys do it.

That is just plane wrong...I don't fly my Bonanza the same way I fly the 767 I earn a living in...they are very different aircraft and require a slighty different technique.

In a light aircraft Power and Attitude = Performance....so too in a heavy jet....just the technique used to arrive at the required performance varies slightly.

[MLS-12D]

So many techniques filter down to GA from Airlines and are assumed to be better simply because that's the way the big boys do it.Yes indeed.

Would those advocating the stick for speed method push the stick forward if low and slow? Of course not, so why confuse a student with that technique?Well, I certainly would, if the airspeed was dangerously slow. I would have thought that this response would be instinctive for all properly trained pilots(?) Better to risk landing short - but under control - then to risk a stall at low altitude. Hauling back on the stick to 'stretch the glide' has killed lots of pilots over the years (see further Langewiesche, especially Chapter 14).

If "low and slow", one is faced with two distinct problems; IMHO, the proper course is to lower the nose and add power (or close the divebrakes, if flying a sailplane).

See generally "Where Does Airspeed Come From?" (http://www.mwenda.com/stick.htm)

[slim_slag]

small adjustments, classic. small adjustments. If you can feel it you have used too much

[MLS-12D]

Yes, of course you're quite correct. Releasing back pressure is usually quite sufficient to avoid a stall ... there is no need to stuff the stick all of the way forward, especially at low altitude.

[Classic]

Who said anything about being at the stall? If low and slow, raising the nose brings you back to the desired glidepath, and simultaneously adding power brings you to your desired speed (and pitches the nose up to help you and reduces the stall speed in an SEP).

You can argue that by making each input simultaneously you would be advocating the same as the 'stick for speed' argument, by using that technique simultaneously too. My point is, why teach a student this non-intuitive way of flying an approach? If both techniques work (as they obviously must, reading this thread) why teach a different one for flying down a slope than for straight and level? Also you are then telling the student (someone with little feel for the aircraft and often still flying by numbers) to change the technique as they enter the flare - bleed the speed off with the throttle and adjust rate of descent with the stick.

It applies to a light aircraft as it does to a heavy.

And Miserlou, MLS, Slim Slag, if you were low and slow (small increments I'm talking about, not at the stall, different problem and different solution altogether) and you lowered the nose before adding power, you would all be down there with the aforementioned gliderpilot.

As DFC says, it's total performance that counts: attitude + power= desired performance and they need to be considered as 2 simultaneously managed parameters. But to teach that you have to teach one coherent technique in your mind which can work for all phases of flight: power for speed, stick for flightpath. (Excepting glide and full power climb, obviously).

Think about it, it too obviously works, and it's instinctive - ask your teenage kid what he/she thinks you should do if slow in an aeroplane!

Oh, and slim slag,
small adjustments, classic. small adjustments. If you can feel it you have used too much

I should have said just a small amount wrong! ;)

[MLS-12D]

Who said anything about being at the stall?Well, fair enough: you only said "low and slow". But I presumed that you meant conditions were approaching critical ... if not, there is little point in the discussion, since otherwise anyone can muddle through with the wrong control movements, and proper training is essentially unnecessary.

ask your teenage kid what he/she thinks you should do if slow in an aeroplane!That is not a reliable source, far less a definite one! Your comment reminds me of the following passage in Langewiesche, p.148:

You know how the controls are labled on an alarm clock or on a kitchen stove. These are arrows marked "on" and "off", "slow" or "fast", "hot" or "cold", telling the customer exactly which way to move what control in order to get what result. Well – here is an idea for one of those unflyable days at the airport; how would you label an airplane’s elevator and throttle?

Your kid brother, knowing what every boy knows about flying, will call this one easy. He will label the throttle “fast” and “slow”. Does not the throttle do to the airplane’s motor exactly what the gas pedal does to an automobile motor? And he will label the stick “up” and “down”. Does not pulling back on the stick make the airplane go up and down? It is only common sense.

Unfortunately, though, the present conventional airplane is not a common-sense contraption; and this labeling of its controls is wrong. It is wrong not only “in theory”; it is wrong also in practice. It is dead wrong; if you really did try to use the controls that way, you would kill yourself. Most fatal airplane crashes happen precisely because the pilot has the controls so labelled in his mind and tries to "elevate" himself, or at least hold himself up, by pulling back desperately on the so-called "elevator". An airplane will not go up, nor will it stay up, simply because the pilot pulls the stick back. In fact, in all the more critical situations of flight, it is all too likely to do exactly the contrary! In the glide, for instance, the farther the stick is held back, the more steeply downward will the flight path be - even though the nose may not point down steeply. In a stall or spin, the ship is dropping precisely just because the stick is held too far back! As for the throttle's being a speed control, the fact is that you can stall with the throttle wide open! Most fatal stall or spin accidents do occur with the engine running nicely at cruising throttle! In fact, when the throttle is open and the propellor blast is hitting the tail, the average airplane actually wants to fly more slowly, and will stall more readily, then with power off! In short, the elevator does not make the airplane go up or down, and the throttle does not make it go fast or slow, and your kid brother is wrong. A similar passage appears in Leighton Collins, Takeoffs and Landings (1981), pp. 7 and 8:

Elevator versus Throttle

As you know, in recent years there has been a lot of discussion about what controls airspeed and what controls altitude. By FAA ukase (sic) we are required to think, or at least to say on our writtens, that the elevator controls altitude and the throttle controls airspeed.

I think this is a horribly dangerous concept when the chips are down, because it can cause pilots to bull back on the stick to go up, or, after an engine failure, to stay up. It is instinctive for people to think in terms of pulling back on the stick to climb or maintain altitude, because it is so logical.

The best example I know of this universal impulse came a few years back. My friend, little Helen Langewiesche, had been given a spin demonstration before soloing a glider. One evening after dinner with Helen and her test-pilot/author, Wolfgang, I asked her what she would do with the stick if ever she found herself nose-down and starting to autoroate. Her answer: "Why dummy, I'd pull the stick back all the way, because if you don't get the nose pointed up instead of down, you're going to fly into the ground". Stick and Rudder, over on the other side of the fireplace, became rigid. I paled. In the ensuing silence, Helen added, "Oh, well, yes, first it is necessary to lower the nose to get some speed, and then you can get headed away from the ground." In short, she knew better, but her initial statement revealed a universal instinct that has to be trained out of people.

A proper concept of airspeed and altitude control is important in thinking about takesoffs and landings, because these are low-altitude operations, and virtually all stall/spin/mush accidents begin close to pattern altitude. And those who, ground-shy, instinctively pull the stick back to gain or maintain altitude, go down.Personally, I think that Langewiesche (Wolfgang, not Helen!) knew, oh, roughly 1,000% more about airmanship than you and I put together, and Chapter 9 in his classic text is definitive on the topic under discussion.

[Miserlou]

The reference to the stall was introduced to show how incorrect your statement was; by going to the extreme of low speed one can find out what the correct action should be.

Reading this post thread, I've begun to wonder how it is that gliders actually fly. Seems impossible, them having no power and all.

Landing an aircraft is achieved by juggling the primary and secondary effects of the elevators. Slowing the aircraft down and controlling the rate of descent. I do power on landings at work sometimes when asked to land long. Just takes longer that's all; attitudes and speeds remain the same and power reduced to idle at the actual point of touchdown instead of at the flare.

Forgive me but I prefer people to understand what actually happens rather than what appears to happen.

The reference to 'ground shy' reminds me of what some-one said once about finding yourself to low to pull out of some or other manouevre. "Aim as far away as you can and try to see how low you can go!"

The technique is to avoid mushing into the ground from a position which you could fly away from.

[MLS-12D]

Reading this post thread, I've begun to wonder how it is that gliders actually fly. Seems impossible, them having no power and all.I agree.

This thread suggests - once again - that the best way to train a pilot is to start him or her in gliders. Only when the basic aeronautic principles have become ingrained though practical experience in sailplanes is it likely that a pilot is truly ready to 'move on' to powered flight (inverted commas because I appreciate that powered flying is not really a step forward, it's just different).

MLS

P.S. to anyone who may be offended by the above: please note that I said "the best way to train a pilot is to start him or her in gliders", not "the best pilots invariably learned to fly in gliders". It is not my intention to denigrate anyone's background or skills. It is quite possible to become an extremely proficient and knowledgeable pilot without having any gliding experience, although that is not the most efficient way.

[Miserlou]

I'll drink to that, MLS!

[MLS-12D]

I looked up the word "ukase", which I had supposed was a typographical error in the Collins' book. I was wrong (hardly the first time!). The Merriam-Webster Online Dictionary defines ukase as: "a proclamation by a Russian emperor or government having the force of law; edict".

That sounds about right, regarding theory imposed by the FAA! ;)

[Classic]

MLS,

If you're going to quote me, quote the whole sentence, and in context.

And yes, I first learnt to fly in gliders. And I would use the appropriate technique for gliders if in one, or if having to glide a powered aircraft (as I stated in my post!)

But I'm not in a glider! I'm on an approach angle less than the glide angle, so I need a combination of power and attitude to maintain it, and teach the simplest way of achieving that. "Muddling through" isn't good enough, so there is a point to the discussion.

Both of your quoted examples refer to handling in the stall regime which require different techniques. That's why they are taught separately and differently as non-normal situations.

As for you claiming I only have 0.1% the airmanship of Langewiesche senior - well, for one thing we're talking handling/instructional technique, not airmanship as I understand it, and for another sinking to personal slights merely undermines your argument.

But as you state, at least the FAA appears to agree with me!

Miserlou,

Your comments refer to the extreme condition of the approaching stall, for which see above.

[AlexL]

Hot damn, I have stirred up a hornets nest here! I thought this was just an innocent query!

Well it has been a very informative thread. Now I've actually finsihed reading the Thom IMC book, I can make a start on "Stick and Rudder".

[IO540]

These long threads just show the quality of instruction in the UK.

Find an instructor who tells you what the trim wheel actually does and you are halfway there.

[High Wing Drifter]

I think the discussion is getting too complicated. I think the basic point is that by teaching stick-speed gas-height the student learns three very important things: 1)The importance of trim, 2) What the attitude does to speed and 3) What the speed does to height.

Once you have grasped this, to me, it does not matter in what order for for what reason you use a specific control, but in your head it is still stick-speed gas-height. When you are on your glideslope and you push the nose down to change the height to stay on the glideslope, in your head you are thinking stick-speed. Because of this you are watching to correct an increase in speed with the throttle, when you reduce throttle to correct the rising speed you know to anticipate more back pressure and to re-trim. Therefore to me, nothing has changed because
how you deal with a specific situation is really down to the specific situation but the rules are unchanged; stick-speed throttle-height...trim trim trim :D

[Classic]

Drifter wrote:
When you are on your glideslope and you push the nose down to change the height to stay on the glideslope, in your head you are thinking stick-speed. Because of this you are watching to correct an increase in speed with the throttle, when you reduce throttle to correct the rising speed you know to anticipate more back pressure and to re-trim.

I agree with that completely, (apart from thinking stick-speed: I think stick-rate of descent and then expect speed to increase as a secondary effect )but your words actually describe perfectly the stick-glidepath, power-speed technique!

I agree it doesn't matter what your thought process is but how you handle the aircraft. My point is: to teach flying the approach, it is easier to understand, and is reinforced by S+L techniques, to consider stick-glidepath, power-speed.

Since time immemorial the 'piece of string' idea has been taught. ie If you move the stick forward, the imaginary piece of string through your sleeves requires you to pull the stick back, and vice versa. If low and slow this works, the other technique doesn't.

If I sat next to someone who at 300' on the approach was 5kts below threshold speed and 100 feet low and they pushed the stick forward I would be inclined to take control off them!

[MLS-12D]

Since time immemorial the 'piece of string' idea has been taught. ie If you move the stick forward, the imaginary piece of string through your sleeves requires you to pull the stick back, and vice versa.:confused: :confused: :confused:

So, it appears that we come down to this. There are two paths for the student pilot to follow:

(1) read, absorb, understand and apply the fundamental principles lucidly explained in Stick and Rudder; or

(2) attempt to master 'helpful' memory aids that are based upon "imaginary strings" and similar artificial concepts.

[Say again s l o w l y]

It's all very well to sneer at people using 'artificial concepts,' but as anyone who's ever taught flying will know, sometimes they are the only way to communicate what you are trying to get across.

My definition of a 'good' student, is not somebody who does exactly what I say, but someone who can make sense of the gobble-de-gook and nonsense that is coming out of my mouth and does what I am thinking.

Not everybody is able to look at dry facts and understand them just like that. I have an engineering degree and an ATPL and I still use some of the silly rhymes and 'artifical concepts' for my own understanding, let alone what I'm trying to put across successfully.

To me the secret of instructing is taking a concept a student is familiar with (driving for instance) and then drawing parallels. Basically going from an area that the student already understands and just extending that knowledge rather than trying to batter in complex concepts straight from the off.

Some people find this unnecessary, but most need something like this or you'll just get the standard smile and nodding head answer when you ask if they understand something complete with glazed eyes.

Anyway, back to the point in hand. On the ILS, speed control with power, stick for rate of descent, bearing in mind that the two are inexorably linked. Oh and get the damn thing trimmed out for the speed you want, it'll make your life a whole lot easier. Get out and practise, it's the only way to get better!

[englishal]

I think this thread is confusing.....

The normal sequence of events (that I use) for flying an ILS is:

at the final approach fix, gear down, 1 stage of flap, set power, pitch and trim. Don't touch power again if I can help it. I'm aiming for 100kts, becasue 100kts will give me a particular time to the missed approach point. Too fast and I'll fly past it and possibly into a mountain, to slow then I may not get in when I could have done.

IF my trimming is a bit dodgey and I am a little low, my airspeed should be above 100 kts, so a bit of back pressure on the elevator will bring me back to the glide path and also slow me down. Now I'm established again, I re trim and get it right this time. I haven't touhed power either, and I'm comming down the GS just how I want to.

A little bit high, and a bit of forward elevator will bring me back to the GS and also increase my speed, which should be below 100 kts becasue I know that at this power setting in this configuration I'll get 100 kts out of her descending on the GS.

*Small* power adjustments can be made to take into account wind, after all my guestimations are based on Ground Speed and and not airspeed. Also I might by flying into somewhere like Van Nuys which has a steeper GS, which I have to take account of and obviously the same power setting and I'll be going too fast.

If you keep messing with the throttle when flying an ILS you will generate a nice Sine curve. Try it on a Sim and analyse your descent later on and you'll see what I mean :D

Cheers

[Miserlou]

Englishal,
Some-one wrote don't fiddle with the power with which I agree-but it will require adjustment.
However, this is the only parameter which is going to need changing as you descend. Without going into density alltitudes, the wind is going to change strength and direction.
Once the aircraft is configured for landing and trimmed to the correct speed then all that remains is to find the correct power setting. You can fly down the glideslope with tiny adjustments of the stick but as soon as you have to maintain any force then you need to adjust the power. The speed range is -0/+10kts.

[High Wing Drifter]

It's all very well to sneer at people using 'artificial concepts,' but as anyone who's ever taught flying will know, sometimes they are the only way to communicate what you are trying to get across.
Agreed and not just flying. A little tangential but just to reinforce the point. Vic Elford wrote in "High Performance Driving", that one technique that helped him keep rediculously poweful racing cars like the Porsche 917 on the track was:

Imagine a piece of string tied to the bottom of the steering wheel with the other end tied to the throttle. As you turn the wheel the throttle comes up and you press the throttle the steering wheel straightens. The basic principle is that the car can only do 100% and everything is a proportion of it. I thought it was a supurb way of explaining it and it has stuck ever since. But like all the models it isn't rote, but really helps form an understanding of what generally works.

Just in case anybody is interested: http://www.amazon.co.uk/exec/obidos/ASIN/0879388498/qid%3D1108664407/202-8267851-7967013

[slim_slag]

On a 3 degree glideslope rate of descent is groundspeed x 5.

100 knots groundspeed is 500ft per min.

Go fly around in practice area and find the power setting which gives you that rate of descent in that plane in the configuration you want to fly the ILS.

Set power setting at that level, intercept glideslope, if you need to then modify power to find rate of descent which will keep you on glideslope when miles out and needle not sensitive. Leave power there unless you have no choice.

Trim it up, use trim to maintain glideslope. Small adjustments, trim, trim, trim.

Don't f**k with anything until you have crossed the threshold, runways with ILS on the end of them are long and you won't run off the end (usually!)

This thread has confused the hell out of me!

[Classic]

slim wrote:
Trim it up, use trim to maintain glideslope. Small adjustments, trim, trim, trim.

Slim, can you tell me what aircraft type you fly an ILS like this on, and whether this was a technique you were taught for IF or whether it's a 'top tip' given by a fellow aviator.

Does it mean that if, say, you are drifting low on the glidepath you just make small pitch up trim inputs until back on the glidepath and then small pitch down trim inputs to maintain it?

I'm just curious as it's not something I've heard of before.

[MLS-12D]

It's all very well to sneer at people using 'artificial concepts,' but as anyone who's ever taught flying will know, sometimes they are the only way to communicate what you are trying to get across.I guess. For some topics, anyway.

But - at the risk of repeating myself - all necessary information on the question posed at the start of this thread is spelt out, in crystal clear language and simple diagrams, without any fancy mathematical theory, in Stick and Rudder. Any student who can't understand that book would seem unsafe to be put in sole charge of an ice cream cone, let alone an aircraft.

I don't mean to insult anyone who has contributed to this thread. My point is simply that Langewiesche got it right the first time, so what's the point in re-inventing the wheel, particularly in a questionable manner?

If someone believes that Stick and Rudder is unreliable, please say so, and explain why you are of that opinion. I'm certainly willing to reconsider my faith in the book, if anyone has plausible criticisms to offer.

Thanks!

[Miserlou]

Slim,
I too would like to know where this 'trim, trim, trim' bull(expletive deleted) comes from.
It really is one of the most ill-advised pieces of advice I've ever come across. If one has too little power applied and keeps trimming up you're going to stall eventually.

The required rate of descent to fly down the glidepath, whatever the angle, will vary according to the wind and there are plenty of conditions which will cause this to change, sea breezes, inversions, friction, coriolis, et al.

Power is the only variable.

MLS, 'Stick and Rudder' didn't get to be the classic it is by being factually incorrect.

[Say again s l o w l y]

Alright, here's the nice simple way to fly an ILS. That I've used about 700 times in the last 12 months.

1) Establish on the localiser at the lower step Height/Alt/whatever you've been cleared to establish at.

2) Start bringing the speed back whilst level, depending on the speed you are going to use on the approach, this can be gear limiting speed down to slightly above the approach speed. Get it trimmed.

3) One dot fly-up indication. Gear down.

4) Half a dot high, props to max, approach flap down. Trim it again. This should bring you down from your slightly higher speed, back to the approach speed you are using.

5) On the glide, bring power back to a nominated (lowish) setting. Down you go. If it's trimmed correctly you shouldn't have to do much.

6) Maintain the LOC and G/S with small corrections. Remember as you descend the wind often changes both in direction and strength. Also as you get closer to the field it all gets more sensitive. Halve any correction you are going to make. If you notice a trend away, stop it initially, then re-establish, don't try to do too much at once and certainly don't fiddle constantly with the trim.

Having said that however, as a very wise old pilot once said to me, Trim in VFR flying is important, in IFR it is essential.

Make all corrections small ones and if it all goes up the spout, go around and try again. It's happened to all of us at one time or another. I remember a controller at a certain large airfield offering to lose the tapes on one approach I made once. Ahem....

Getting bogged down in the semantics of point and power Vs. anything else is a waste of time, since there isn't really two different ways of doing it. Watch someone who knows what they are doing and they'll be manipulating the attitude and power at the same time without even thinking about it.

At the end of the day the aim is to get safely onto the ground, the minutae of how you got there is irrelevant.

What works for you?

7) get visual, stick it on the numbers. Go get a cup of tea.

As for the comment about only some topics needing idiots guides, not true at all. Every student is different, some find Nav difficult, others engine theory or aerodynamics. I personally have different explanations for virtually every topic we cover and at some time or other I've had to use all of them. I'm still trying to think of more since there are somethings I don't think I explain in easy enough terms.

The attitude that says untechnically minded people shouldn't be allowed near aircraft is rubbish. There are many things that 'convention' says we should understand otherwise we aren't safe. Again nonsense. Knowing exactly how some highly technical piece of kit works isn't the most important thing. Knowing how to cope if it fails or what the signs are of it's imminent failure is far more important than what some random widget does.

Flying is sometimes so far up it's own backside it's untrue, these barriers to entry are usually perpetuated by people who aren't exactly ace of the base themselves. Have a look in any flying club and the person holding court is usually the biggest muppet there. As you can probably tell, it's one of my pet hates!!

[DFC]

Miserlou, MLS-12D,

Reading this post thread, I've begun to wonder how it is that gliders actually fly. Seems impossible, them having no power and all

Well gliders can't "fly" they can only glide. A glider flying at a constant airspeed can not maintain level flight and it can not climb...........all it can do is glide - descend - convert potential energy.

Perhaps I should repeat a statement I made earlier - If one makes a glide approach at say 70Kt and next time one wants to make a more shallow approach but also at 70Kt - one will have to use power to maintain the airspeed at 70Kt..........similarly if one is descending with power at 70Kt and one wants to make the approach angle more shallow for whatever reason - one will have to increase power to maintain 70Kt on this more shallow approach...........if one wants to make a steeper approach at 70Kt, one will have to reduce the power to avoid having a higher speed.

Now tell me that the reason why we are maintaining 70Kt is because I am moving the stick?

Regards,

DFC

[Say again s l o w l y]

No. If you move the stick, you'll change the speed.

If the aircraft is trimmed properly, then by slowly adding and reducing power, the a/c should climb and descend whilst maintaining roughly the same speed. Big changes in pwer setting will have an unsettling effect and the speed may change dramatically.

A glider can only maintain a constant airspeed and constant alt if in an updraught, basically the vertical movement of air is adding energy into the system. What we power pilots do by burning some fuel.

DFC, I do know it's a rhetorical question, but I couldn't help myself!

[Miserlou]

Airbrakes are very effective at controlling vertical speed and are operated in much the same way as the throttle; steeper descent when fully aft, shallow descent when fully forward. If one changes the pitch angle the speed will change.

May be easier for you DFC if we go back to effects of controls because I feel there's some fundamental errors in your understanding.
If you're flying straight and level and want to go up you have to add power.
If you want to fly faster you add power too but then you have to PUSH THE NOSE FORWARD so as not to climb.

I think you may be being confused by the fact that the pitch attitude for a given speed changes slightly due to the effects of the propwash over the wings and tailplane.

[slim_slag]

miserlou, not sure where to start with your post, I shall be charitable and assume you don't understand my use of 'trim it up' :) As I said, some of the stuff on this thread has confused the hell out of me.

classic, it's a 'top tip' to be used in a basic training spam-can. Basically the moral of the story is simply that if you get your power right early on you don't need to mess with pitch very much at all to fly a constant angle approach. Small corrections are easily effected by the trim wheel, if you end up needing large corrections then you have your power wrong so you need to change it. It's vitally important to keep ahead of the plane at all times and you will keep the needles in the doughnut. It may be herecy to some CAA examiners but it will get you on the ground very nicely, try it and see, if you don't like it don't use it.

Isn't getting the power right early on the basic premise behind how you teach a pre-solo student how to fly from abeam the numbers to the threshold? Ever heard it said 'power to 1800 abeam the numbers'? In other more interesting planes you might say 'power to idle' abeam the numbers. Both ways, once you have set power to a certain level you don't mess with it.

[Classic]

That's it, a 'top tip'. It's not a correct technique, it's not recommended and formally taught as a way of adjusting to maintain a glidepath. By flying any aircraft in this way you are effectively destabilising the approach. What are you doing with the control column when applying the trim? Just letting the nose drift up and down to achieve the glidepath? If you do that and have some sort of distraction for a time, the aircraft will continue to diverge from the glidepath at an increasing rate.

The reason I make these comments is that student or inexperienced pilots reading this thread may take what you say as sound advice and could find themselves with problems later. You should use the correct techniques in a spam can as much as any other aircraft f you wish to develop as a pilot, and bad habits like that will be spotted in a flash and jumped on further down a pilot's prospective career ( if they aren't already in a PPL flight check with an instructor).

The whole basis of basic flying training is to develop the idea that by setting an attitude, trimming to maintain it (NB NOT to change it) and setting the appropriate power setting, you will achieve the performance that you need.

[Say again s l o w l y]

Both ways, once you have set power to a certain level you don't mess with it.

Oooh I hate it when people use sweeping statements like that. Do you mean you've done something wrong if you've had to add or take away some power? Nonsense, you do what is required to keep the a/c where you want it.

There is no mythical, all encompassing way to fly aircraft, especially in the approach and landing phase. Are your actions always exactly the same on every approach? What happens when conditions are different?

"Top tips" are only used when somebody hasn't learnt the basics correctly in the first place. They mostly rank alongside Baldrick's cunning plans. Some do have merit and I myself don't always fly the way the book says, an example of differing techniques is cross wind landings, wing down, crabbed or a combination each has it's merit, but what do you find easier?

The only way I can understand what Slim is talking about is this, You are sliding down the glide slope and you start to sink below. I would at this point put a tiny nudge of back trim as I arrested the rate of descent, since it was obviously incorrect, but this is my personal way of doing it. I would expected an inexperienced student to re-establish on the glide using the primary flight controls, and then re-trim to help maintain.
Again this is semantics, but we need to keep techniques as simple as possible in the early stages, until a good understanding of what happens is built up, only then can we start to use 'short cuts.'

[slim_slag]

classic,

Note my use of the word 'heretic' in my first post. As I said, if you don't like it don't use it. With all due respect I think you have missed what I am saying.

SaS,

Not sure if you are agreeing with me or not, and I am also not sure whether you think you should use power or pitch to maintain a constant angle approach. I think what you have just said in your final post is correct, I think. Isn't the trim wheel connected to the same cable that the yoke is connected to?

This place would be so boring without a bit of controversy :)

[Say again s l o w l y]

In a way I'm agreeing, in that if you know the thing is trimmed wrong, you change it, but I wouldn't advocate just using the trim alone instead of the primary control.

I don't think that either power or pitch should be used in isolation, but a combination of the two since when one changes something in an aircraft it effects something else as well.

I think you'll find that the yoke/stick is not connected to the same cable as the trim. That does show a bit of a misunderstanding.
Most a/c have trim tabs that you are moving, so you are not directly moving the elevator with the trim wheel, but the tab.

[slim_slag]

SoS,

Yes, depends on the plane (and I was asking a question :)). Again, if you don't like it, don't do it!

[MLS-12D]

Well gliders can't "fly" they can only glide.See Miserlou's post, above.

I am not surprised to see that while people venture their own theories (which of course is their right), no one has suggested any criticisms of Langewiesche. As Miserlou said, "Stick and Rudder didn't get to be the classic it is by being factually incorrect."

On the same note, here is a quotation from Flying Magazine columnist Peter Garrison (another pilot who also knows more about practical aerodynamics and the theory of flight than the bunch of us together) in his 1980 book, Flying Airplanes: The First Hundred Hours (p.10):

Wolfgang Langewiesche's classic Stick and Rudder is the only masterpiece on the subject of learning to fly that I have seen. It is a thorough and correct introduction to the theory of flight for the practical aviator, and any pilot who takes his flying seriously ought to have read it carefully. It is dated, but being a really fine boook, it does not suffer much from age. Stick and Rudder seems to be free of errors and misconceptions; if it says one thing and your instructor says another, suspect your instructor, and keep quiet.He continues, in a passage that may well serve as a denouement for this thread:

When I learned to fly, I didn't use any book at all, and it is quite possible to fly skillfully with a complete misunderstanding of some of the principles of flight. Most pilots do it all the time. Unless your jaw needs exercise, don't get into arguments with people about how things work. Read, listen, compare, and practice. You are certain to be exposed to misinformation or contradictions about the theory of flight; don't get worked up over it. It is the unavoidable consequence of nonscientists inhabiting a field that is, on the scientic level, quite complex.

[Say again s l o w l y]

Having not read either book I can't really comment on what is contained within them, but I am able to comment on some of the nonsense that gets put up on these boards.

Seems I must not be a 'serious' pilot then!! Again nonsense, but pretty much what I expect from some of the raging ego's that inhabit the private flying world.

Why would you keep quiet if you don't understand something that your instructor is trying to put across? Are you advocating that a book is a better teacher than the FI standing in front of you?

I have always got into discussions with people about how things work and this has always helped my understanding, are you suggesting that people should sit and just ponder and then come up with their own misconceptions? If a student didn't understand what I am trying to explain, I would be mortified if they didn't ask me to clarify.

What all this has to do with flying an ILS I don't know and also what has glider flying got to do with it aswell? I can't remember ever seeing a glider coming down the slope.

[slim_slag]

SoS,

You should go and read Stick and Rudder. There is one bit that makes me smile ( from memory it's something about the new fangled nose wheel planes coming out which will make it impossible to go off the side of the runway like you can with a taildragger) but it really is top notch.

Are you advocating that a book is a better teacher than the FI standing in front of you?

Read the book and think about that one again.

If you read the original post getting onto ILS discussions is not too far fetched. Also an ILS is excellent subject matter to discuss how pitch and power are used to follow a chosen path in the sky.

[Miserlou]

What I think MLS is saying is don't get into discussions about that which you have insufficient knowledge. Clearly there are some on here who should learn from that.

If you don't understand how a glider flies then you're at a disadvantage when understanding the finer points of powered flight. The aerodynamics are the same, the energy is derived from different sources.

It would be a sad state of affairs if the accident rate for gliders were the same as the accident rate for powered aircraft/engine failure accidents.

[Say again s l o w l y]

I'll try and find a copy of the book, but no matter how good it is, it can never be a substitute for a competent instructor. I have learnt more from talking and listening to people who are acknowledged experts than from reading any amount of books. Useful tools, but not the be all and end all.

Unfortunately there are many people on this board who seem to enjoy 'instructor bashing' at any opportunity. I have met a large number of these types in the flying world and to a man (yes, they have all been male) their attitude has panned out in the low standards of flying they ahve subsequently demonstrated.

Not all FI's are brilliant by a long shot, but given the time to do the job properly, you may be surprised at the levels of knowledge many have. Think about that next time you are telling someone that it is possible to complete a licence in less than 60 Hrs.

An ILS is NOT a good place to be discussing how to fly the aircraft competently. When you have reached that stage of training. I w ould assume that basic handling issues such as this would be taken care of, to allow you to concentrate on the job in hand i.e flying the ILS safely and keeping a mental picture of what's going on around you, NOT worrying about which lever you pull to make the a/c react how you want it.

Are gliders safer per hour of flying?

The aerodynamics of a glider and a powered aircraft are not the same. How can they be. They have totally different ways of operating.
The speeds are higher, the weight greater, airfoil sections different, plan forms utterly different, no issues such as thrust reaction or prop slipstream. You cannot argue that flying a glider is the same as flying a fixed wing or vice versa. Whilst the basic aerodynamic controls are roughly the same, how they effect the system is different. If you have lazy feet in a glider, ther is a much more pronounced effect than in a stubby little pwered a/c.

[slim_slag]

Miserlou,

In 2000 (last figures I can be bothered to find) in the US:

SEPS: 7.61 accidents and 1.27 fatal accidents per 100,000 hours flown

Gliders: 20.36 accidents and 3.18 fatal accidents per 100,000 hours flown

Now what was that you were saying???

SoS,

Chill :)

[MLS-12D]

Seems I must not be a 'serious' pilot then!! Again nonsense, but pretty much what I expect from some of the raging ego's that inhabit the private flying world.Oh for crying out loud. Please re-read my post.

I didn't say that anyone who hasn't read Stick and Rudder is not a serious pilot. I merely quoted from a book that suggested that any pilot who takes his flying seriously should have read it.

If the book has previously escaped your attention, fine; there are plenty of great books out there that I don't know about. Now that it has been brought to your attention, I have no reason to believe that you will not attempt to track it down and see whether it is as good as the rest of us say it is. And if, after having read it, you have some criticisms, I will be happy to hear them, and promise to do so with an open mind.

Why would you keep quiet if you don't understand something that your instructor is trying to put across? Are you advocating that a book is a better teacher than the FI standing in front of you?Point one: again, I was quoting a book. If you don't like what was said, just don't buy the book. Giving me a hard time about its contents is pointless and unnecessary.

Point two: yes, often the author of a flying book is much more experienced and knowledgeable than a run-of-the-mill flight instructor (especially those who are only 'building time' en route to an airline career). Is this really controversial?

Point three: While I can't read Peter Garrison's mind (refer to point one, supra), I speculate that he is suggesting that the student not engage in a discussion with his instructor because that might put the latter on the defensive and might well lead to hard feelings. E.g., just look at how quick you were to attack me!

Unfortunately there are many people on this board who seem to enjoy 'instructor bashing' at any opportunity.Here is my take on instructors: some are good; some are bad;a few are great; and a few are dreadful. By the way, I am one myself.

You cannot argue that flying a glider is the same as flying a fixed wing or vice versa. Actually I can, and will, argue that point. As anyone who has the slightest acquaintance with gliders knows, they are - surprise! - fixed wing aircraft. :rolleyes:

[Miserlou]

Your statistics are as the lamp-post to a drunk man...more for support than illumination!

Now let's see the statistics for the UK, stall/spin(including following engine failure) per flight. I think you'll find a different result. These factors are only mentioned in the appendices. Running out of fuel or suffering an engine failure should not lead to a fatal accident.

What I was saying is also difficult to see in the statistics because stall/spin accidents which occur after an engine failure come under 'engine failure' which fails to show the true cause of an accident.

A 747 at idle thrust is nothing more than an overgrown glider. Whilst the systems may be vastly more complicated, that's all it is. Do they suddenly get new rules to fly by when they have all engine flame-outs? I think not!
Thanks for the laugh.

[DFC]

Miserlou,

[I]Airbrakes are very effective at controlling vertical speed [/B].

I am going to be very bold and say - No they are not!!!!!!

Airbrakes are very good at increasing drag and drag opposes thrust and at a set thrust an increase in drag will cause a reducton in airspeed.

The rate of descent may change as a result of the reduction in speed provided by the speed brake or if the pilot choses change the descent gradient i.e. hit the ground sooner which has a secondary effect of maintaining the speed.

Theoretical aircraft with locked controlls flying straight and level at 150Kt........the pilot extends the airbrakes slightly...........the aircraft slows down............lift reduces and the aircraft descends.....the path of the aircraft through space has changed. If the controls are unlocked and the pilot uses the control stick to return the direction of the movement vector back to where is was - the overall result will be the aircraft travelling along the original profile at a lower speed but a higher angle of attack (to counteract the loss of lift)

Thus the pilot has altered the speed with the airbrakes and then used the stick to restore the flight vector through space.


This argument is like the one where pilots say ailerons roll the aircraft and others say ailerons cause yaw..........both are correct but think about how we actually use the ailerons and what we considder primary effects and secondary effect. The last time I checked, the change in airspeed was a secondary effect of moving the elevator the primary effect is to pitch the nose up or down.

Most aircraft have a Power/Drag couple. On some aircraft, it is possible to control pitch with changes in power - would miserlou when flying that type use stick for speed and power to alter pitch attitude?..........or would he say that the stick is for altering attitude the change in speed is simply a secondary effect and the power is for altering thrust not for changing the attitude which is just a secondary effect!

Regards,

DFC

[Miserlou]

Thank you, DFC, very bold of you.

Airbrakes, the common name for spoilers, so-called because they spoil the airflow and in so doing decrease the lift. In opening into the airflow they also create drag which causes the speed to begin to decay reducing the airflow over the tail, in turn reducing the tail down force. This creates a nose down pitch change whereby the speed will increase again to restore the airflow over the tail until the stable situation is restored (typically after a couple of oscillations).

The new situation leaves the aircraft in a steeper descent at the same speed with a slightly different pitch attitude due to the change in configuration.
How you lose energy is up to you but if the pilot is now flying level at a lower speed then he will have a higher nose attitude.

You've really answered your own question where you mention the higher angle of attack. Speed is only a fallacious way of expressing angle of attack (for which, see Stick and Rudder). I see no case to answer; you can't change the principles of flight.

The pitch/power couple is part of the stability of the aircraft so that, as an example, if the engine were to fail the nose tends to fall. Then the speed doesn't have to decay so far before the stable, trimmed situation is restored.

Let's not go into exceptions like the Lake. It still flies faster when you put the nose down.

If moving the nose up and down is the primary, and controlling the speed is the secondary, then the flightpath must be the tertiary effect of the control. The discussion here is that the elevator controls the altitude/vertical speed before the attitude/speed.

Thanks for backing me up on that!

[ShyTorque]

"Airbrakes, the common name for spoilers, so-called because they spoil the airflow and in so doing decrease the lift."

Different things, where I was taught.

Spoilers popped up out of the wing and spoiled the lift. Some gliders have them.

Airbrakes popped open, not out of the wing, and created drag.
Like on the Buccaneer, the Hawk or the BAE 146, for example.

[Final 3 Greens]

I've been away on business for a few days and am amazed that this thread has run to 6 pages now, with such strong opinions from different perspectives.

Two things are clear:

1 - the laws of physics create a complex system within which the flight regime operates

2 - we create meta models to help us think about the complex system and in this specific instance to create metaphors that are easy for students to learn and which deal with the complexity by chunking the whole into easy to digest portions - e.g. How do you eat an elephant. Some learn one way, others another and a few learn multiple models

The impact of such powerful learning can been seen in the points and counter points in this thread.

As someone who designs learning programmes (in another equally complex field), I always take great care when creating powerful metaphors, since the subsequent "unlearning" required to move on to a different level of sophistication can be challenging.

People tend to scan the environment for information to support their beliefs and discard new learning because it does not fit the meta model indelibly burned into their unconscious mind during the training process.

Perhaps the real learning point from this thread is for instructors - when you are teaching one method or the other, an explanation of the context would be helpful, so that PPLs moving on to IRs or jet ops suffer less cognitive dissonance (confusion) when confronted with apaprently contradictory approaches.

In fact, I thought that Chimbu Chuckles summarised it pretty elegantly.

[Miserlou]

Shytorque,
The spoilers on a glider in the UK are called airbrakes, those which extend above and below the wing, and are used primarily to control the rate of descent on the final approach. They can also be used when descending 'on tow' so as not to overtake the tug.

Not really my fault that they are incorrectly named.

DFC,
I'd most certainly agree that the most important lessons may be for the instructor. A fact which wasn't missed by the CAA in one of the accident summaries noting LOC/VMC accidents due to failures in basic handling, to which I also refered earlier, as a possible symptom of poor instruction. I'm not instructor bashing (unless they think that the throttle controls the speed), just drawing the same conclusion.

The most simple system to break the principles of flight down into, or build up from, must be the glider, hence the references here.
We must at all costs avoid cognitive dissonance!

[ShyTorque]

Did a bit of gliding myself, nearly 35 years ago now, and I'm sure they were called spoilers back then. Having done a web search on the subject, I found about an equal number of references to "spoilers" on glider wings.

So we ought at all costs avoid perpetuating misnomers. ;)

I'll just maintain my stance that airbrakes slow the aircraft down, spoilers spoil lift. RAF CFS told me so and they've seemed to do all right so far. :E

[Final 3 Greens]

Regardless of the correctness of the nomenclature, the two gliding clubs where I learned to fly in the 80s both referred to the items that popped out of the wing as "air brakes."

Looking back at an ancient document, it discusses the use of "half airbrake" on final approach.

[blagger]

I currently fly the Vigilant motorglider for the Air Cadets and we most definately refer to Airbrakes - never spoilers. The key thing to understand with them is not only the effect they have, but how we actually use them (I agree with previous posts that effect of a control can't always have a generic answer - it depends how you employ it/what are the other factors).

For example, we teach effect of airbrake initially - which is an increased rate of descent (non-linear as a/b is most effective through the 1st 1/3 of their range) and nose pitches down, hence increased speed (due to movement of centre of pressure) , put a/b in and effect reverses. We then teach the use of a/b, which is deploy a/b and control the pitch down with back stick to maintain the desired speed - so in effect we are using them to control rate of descent and not decrease speed. This is then employed to allow bloggs to control his rate of descent with regard to an aiming point on the approach, while maintaining a constant airspeed (which will inevitably alter by +/- 10kts as bloggs weaves his way down to somewhere on the airfield!!)

[ShyTorque]

Blagger,

From what you just described, pitching nose down is a secondary effect of control, not a primary effect. If you held a constant IAS, then what happens?

So "AIRBRAKES" ON = vertical SPEED INCREASED at the same IAS.

and "AIRBRAKES" OFF = vertical SPEED REDUCED at the same IAS.

That makes 'em technically (lift) spoilers / dump, not airbrakes!

When I was taught gliding, and it was by RAF instructors, I'm certain we were just taught to approach at a constant IAS but use WING SPOILERS where necessary to adjust the rate of descent to make the aiming point on the field, the opposite of power on a powered aircraft.

Well, if you're flying 'em now then I have to bow to your more recent currency regarding terminology, but it still doesn't seem logical to my old fashioned and simple brain to refer to them as airbrakes, when the primary effect is to reduce lift!

If I operate my car brakes the speed reduces, not increases. If I operate (real) airbrakes, either split ones at the rear of the fuselage like the Buccaneer or BAE146, or a single blade under the fuselage like the Hawk (no lift dump in either case) my aircraft slows down also. The reduction of lift comes as a function of reduced airspeed, not as a primary effect of use of the airbrake.

Did it all change when colour telly came in? :E

[High Wing Drifter]

I think another specific benefit of drag inducers (air brakes, et al) is that they move the drag curve up and left thus moving the min power and min drag points to a lower IAS. This, I assume, is a major benefit when on the approach as the IAS will more speed stable as a result (tend not to drop away so quickly).

[blagger]

Shy Torque,

I know what you're saying - if you hold the attitude and deploy the airbrake/spoilers (!) you will see a decrease in speed, when we teach maintaining the desired speed (65kts on the approach) this will be at a new attitude with a/b out than before without.

As for the move in the drag curves, I got this question by a CAA examiner recently - he asked me why the BAe146 approaches with it's airbrakes out and this is the reason why!

As an aside, when I'm flying SEP I always use the throttle for speed technique from my 400ft reference point on approach - much easier to get the thing down on the numbers consistently than with any other method.

[shortstripper]

Having only just picked up on this thread I'm utterly amazed how long it is! ... so I'll add my bit too :E

I hate to agree with SAS but his... Getting bogged down in the semantics of point and power Vs. anything else is a waste of time, since there isn't really two different ways of doing it. Watch someone who knows what they are doing and they'll be manipulating the attitude and power at the same time without even thinking about it. is the most sensible bit I've seen.

I came from gliding to power but haven't flown gliders for many years now. Most of my glider training transfered to the way I fly powered aircraft (rightly or wrongly?) and seems to have been OK for the simple SEP's that I have predominately flown. In gliders I was always taught attitude controls speed and rate of descent (taking lift and sink out) was controlled by airbrakes/spoilers. I quickly applied the same logic to power with throttle controlling ROD instead of airbrake ... it also has the added advantage of acting as my very own thermal to allow climb :D So when I'm on the approach, if I'm high I pull airbrake/reduce power, and if I'm low I reduce airbrake/add power. Obviously all these controls have further effects which kind of simply takes the qustion marks away from the title of this subject! and reinforces SAS's above quote.

Of course in an engine failure, speed can't be controlled by throttle anyway you work it and so has to be controlled by stick! ROD can be finely controlled by sideslip if needs be, but is essentially controlled by the glide angle and sink rate of the aircraft.

There seems to be way too much analysis here ... Obi-Wan would have lost Luke's trust if he'd said "Consider all the ways you can use your power Luke, then in the given time frame select the most appropriate and apply in a carefully controlled manner". Nope, he preferred "Feel the force Luke" :ok:

SS

PS. Bound to be wrong, but in the gliding fraternity when I was active, we used to refer to top-only drag inducers as spoilers, and split top and bottom ones as airbrakes. Airbrakes and spoilers have one main difference to flaps in that they normally do not effect stall speed (but can effect stall attitude).