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View Full Version : Throttle for airspeed?????


Wing & Prayer
2nd Dec 1999, 12:15
Always interesting to get some ideas on this topic... Is it throttle for airspeed on base and finals, with pitch (control coloumn) used for rate of descent/attitude, or vice versa, or is it a combination of both???

Charlie Foxtrot India
2nd Dec 1999, 13:23
Attitude = Airpseed
Power = Rate of Descent
for the little ones, anyway.


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Wee Weasley Welshman
2nd Dec 1999, 23:01
Agreed. Although if I have a PPL student intending to go on and become commercial I progress this on to the reverse case power=airspeed pitch=glidepath as this will aid them when they come to ILS and large aircraft ops.

Cheers

WWW

Meeb
2nd Dec 1999, 23:11
WWW is quite right, although CFI has a point regarding small aircraft. However power for airspeed is really the only way to fly an ILS. Also, anyone involved in military flying will always use point and power! In real life its a combination of both.

WileyP
3rd Dec 1999, 01:34
Oh boy are we going to get this one started or what?!

(1) When power/drag is available and variable, power/drag controls airspeed and pitch controls vertical speed.

(2) When power/drag is fixed, pitch controls airspeed and God controls vertical speed.

Case #1 happens when you begin your takeoff roll, in cruise flight (regular or slow cruise), during descents and on approaches and after the landing.

Case #2 is more evident during your climb, when the engine fails and during a descent when you've already got power off and all the drag deployed.

There are, of course, hundreds of variables and variations which must be dealt with on an individual basis. I'll spare the minutia.

Good luck nailing this one down!

...and above all,

FLY SAFE!

WileyP

Realist
3rd Dec 1999, 03:31
Attitude+power=performance

Airprox
3rd Dec 1999, 07:28
I teach 'Point and power'. Select your aiming point and adjust power and flaps to control the speed.

Of course realy its a combination of both if you increase power your nose wants to pitch up so you increase forward pressure to maintain your attitude and your speed increases. You just cannot do one with out the other.

I explain this marriage of thrust/attitude to my students and point and power seems the easyist way to teach it.

A few of you seem to disagree, fair enough as I said its a combination of both, but I'll tell you one thing the students taught 'point and power' learn quicker and have more stable approaches with very little throttle movement.

BEagle
3rd Dec 1999, 11:09
Airprox - absolutely right, mon brave!! When you're NOT aiming at a specific point on ther ground then yes, control column controls attitude and hence speed, throttle controls rate of climb/descent at a constant airspeed. But when AIMING at your touchdown point, assuming that you've achieved an acceptable descent point, then the interrelation of the control column and throttle to sort out 'point and power' is so, so easy to teach and use!! I teach it both in little spamcans and in large 4-jets and, as Airprox says, students catch on to it very, very easily!!

mickg
3rd Dec 1999, 23:58
On the Tucano we fly a descending finals turn from the end of the d/w leg to a "300' pt" on the extended CL.
On the finals turn: pwr=ROD, pitch=IAS (for a constant IAS).
On the final app: pwr=IAS, pitch=Flight path (for a constant flight path).The aim on fin app is for a steady spd decay from 110kts to Vth (90-95kts).

This concurs with the above msg in that when you have an aiming point pwr=spd and pitch=flight path.

Capt Homesick
5th Dec 1999, 04:25
I learnt to fly, using power for RoD and attitude for IAS on the approach.
By the time I was instructing, CFS wanted us to use "Point and Power" (ie use attitude to control flight path, and control speed with power) for the Flying Schol cadets. They were paying, so ok!
It works surprisingly well, but as we all know IAS and RoD are a result of the combination of power and attitude, so both methods are just ways to avoid confusing the stude anyway!
On some a/c, though, one method is definitely better than the other. For example, the Katana has an extreme change of lift with attitude change (high aspect ratio wing), so point and power is better, as you get too much of a lift change if you pitch for IAS, (that DROP when you pitch down for an extra 5 knots got my attention every time). I'm sure other contributors will have examples of a/c which are better flown on power=RoD, Att=IAS.

Skycop
6th Dec 1999, 09:04
Airprox, airbrakes, not flaps are for controlling speed. I agree that point and squirt results in a more accurate touchdown point. The only thing that a basic stude needs to be aware of to tie up the whole technique is the limits of too steep and too shallow an approach. p.s. Don't try this at home on helicopters.

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May the Force be with you - and may Gravity treat you gently..

Airprox
7th Dec 1999, 06:39
There aren't any speed brakes on small training aircraft but flaps will work just as well.

Realist
7th Dec 1999, 07:51
Point & Click is a hell of a way to fly a stable 3 degree approach.

Pub 45
9th Dec 1999, 15:01
I am a convertee to 'point and power'.

I think 'power for altitude' is fine for providing a safety net for new students. But as the student develops in skill and confidence, the improvement in accuracy is far greater with PnP. Also stands them in good stead for IFR training.

de La Valette
12th Dec 1999, 14:56
CFI - That is an old teaching, since discredited I fear.
Airprox - You are dead right. When starting on circuits with new student I prefer to use throttle off glides right from the start. ie Turn level base, and when sure you can glide in, close the throttle completely and use flap as needed (Cessna 150's et al) Same as Tiger Moth technique 50 years ago. Speeds are the same anyway. Naturally you have to control IAS with elevator in a glide. Teaches good judgement nice and early. It works, too. For powered approaches use fixed aiming point and control IAS with throttle. Actually it is a combination.
Same when using VASIS or ILS. Works wonders and I seem to get students to go solo between 6 and 8 hours using the above techniques. Forgive me if I now hurriedly exit stage left before the knives arrive!

4dogs
12th Dec 1999, 18:49
CFI,

I am with DLV.

I think that we are all talking only of final, although the base turn is often where the transition in techniques occurs.

If the aeroplane is slow enough, light enough and is propellor driven, your technique will not produce much difference in outcome, mainly because the responses to attitude changes can be relatively slow and the response to power changes can be quite dramatic. If the aeroplane is fast, heavy, relatively low drag and jet powered, your technique invariably leads to PIOs and unstable approaches - simply because the results of attitude changes occur quickly and the response to power changes can be relatively slow.

Like so many of the really good things in life, once you have done it, you won't go back! Having said that, PnP (I like that!) only works within a defined glidepath range similar to an ILS glideslope - once outside it, then you must fly back into the window using attitude for airspeed and power for rate of climb/descent and then resume controlling your flight path vector to impact the ground at your point of choosing.

Please don't hide it from them once they have conquered the basics - the absence of the technique later on cancause them considerable and unnecessary heartache.

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Stay Alive,

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