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Sam Rutherford
7th Jul 2008, 07:18
Any thoughts/tips?

How to combine visibility from the ground and pax comfort?!

Thanks, Sam.

BackPacker
7th Jul 2008, 09:09
You can't combine passenger comfort with perfection looking from the ground.

For passenger comfort a wing waggle needs to be flown in balance. This means basically a succession of balanced turns, rolling into and out of the turn rather slowly so that your head doesn't bang against the side windows. But this will look rather sloppy from the ground.

To look good from the ground you need to fly straight and just roll along the longitudinal axis of the plane. By definition you're not flying in balance and in fact, in most aircraft you'll find that you will have to cross-control to stay on heading (a roll left needs a bit of right rudder and slight forward push).

Fortunately a wing waggle as a way of saying goodbye (after a photo orbit, say) only needs to be about 20 degrees either side to be visible from the ground. Once left, once right is enough and most passengers are able to survive this. Especially if they've just survived a few minutes of steep turns to get into the right position for the pictures.

It's a different matter for the wing waggle that's marking the start of your aerobatics sequence. The rule is three wing drops (all to one side or alternating) and they need to be 45 degrees. Unless you have a thoroughbred aerobatics plane, this maneuver will rob you of somewhere between 10 and 20 knots. Especially if you try to do them the proper way, compensating for adverse yaw with the rudder and so forth.

Must admit in an aerobatics sequence passenger comfort is nowhere near the top of the priority list.

ShyTorque
7th Jul 2008, 09:24
I'm a bit concerned why a pilot should be asking this.

A high time pilot wouldn't be asking (he would know). Any pilot with common sense wouldn't try to impress folk on the ground whilst carrying passengers, or at all for that matter. Unless you have a display authority, leave this sort of thing alone. It can and has, ended in disaster.

Here's a discussion of just one example:

http://www.pprune.org/forums/private-flying/235149-display-aircraft-fatal-crash-cambridge.html

BackPacker
7th Jul 2008, 09:30
Shy, you're absolutely right.

Let me just say I hope every pilot realizes that if you are low&slow and then fly cross-controlled/out of balance, you're cooking up a recipe for disaster!

Sam Rutherford
7th Jul 2008, 09:40
I fly over my Mum's house occasionally, with the kids on board. They love it.

I do this at about 1000' agl, gentle angles of roll, at about 80kts - I see NOTHING unsafe in this whatsoever.

I was wondering if anyone had a technique for making it visible from the ground without sticking the kids up against the windows :E.

Live a little...;)

Sam.


I'm going to duck for cover now...

ShyTorque
7th Jul 2008, 19:36
Live a little...

Thanks for your advice; I have already been living (and flying) quite a lot, really. ;)

First solo glider 37 yrs ago, PPL training 35 years ago. Then nearly two decades of military flying, including basic and advanced instruction, well beyond PPL, teaching aeros, close formation, instrument flying etc. A fair bit of rotary too, including display flying. Teaching at basic and advanced levels to combat ready. Now done nearly another fifteen years of civvie stuff and I certainly do intend to carry "living a little" for a long time yet.

However, your serious topic.....

Sadly, quite a few of my friends and colleagues, some of them supposed "sharp cookies", are sadly no longer here to live even a little. By coincidence with your last posting, one of them got himself killed by getting into something beyond his handling capabilities at 1,000 ft, and the aircraft went out of control. His girlfriend was also in the accident, she was in the back seat. She survived, but nearly twenty years on, is no longer the same person, physically and mentally. I went to the accident site, a very sorry scene, as it was very close to my home. I still have to fly over it regularly and so I won't forget....

My real point is that requesting advice from a public website isn't the safest way for inexperienced pilots to improve their handling skills. In any event, if you fly a regular Cessna or a Piper, a "wing waggle" is more likely to look like a wing "wallow" from the ground.

Take care out there, especially when your kids are on board; your folks on the ground will be impressed enough just by looking up and seeing you there. :ok:

Zulu Alpha
7th Jul 2008, 22:09
perfect wing waggle!

What is a perfect wing waggle? Anything less than 45 degrees is more likely to look like you are wobbling about and can't fly straight.

Generally what feels impressive in the aircraft doesn't look anything like as impressive from the ground.

As has been mentioned, aerobatics competitors start with wing rocks but they must be over 45 degrees in order to be clearly seen from the ground.

Opening and closing the throttle is a much better way to get the attention of someone on the ground.

Normally, if someone is expecting you and you circle overhead then that is enough.

ZA

eharding
7th Jul 2008, 22:44
Inverted wing-rocks can be amusing, but the most impressive I've seen recently were at Duxford where one competitor deemed that his first freestyle figure required sufficient oomph to require his wing rocks be performed on a vertical down-line rather than the more traditional 45 degree dive.

To the OP - attempted public high-jinks in touring aircraft invariably result in embarrassment, passenger nausea and sometimes a lot worse. A more impressive feat would be to give your Ma an expected time overhead and arrive there to the *precise* second....(...and then maybe have one of the sprogs send her a text message...)

Whirlygig
7th Jul 2008, 22:54
How about a quick flash of the landing light instead? :}

Cheers

Whirls

Mark1234
8th Jul 2008, 01:14
Let me just say I hope every pilot realizes that if you are low&slow and then fly cross-controlled/out of balance, you're cooking up a recipe for disaster!

You mean like every landing I do with a crosswind?

Actually, come to think of it you're right :}


Seriously, I'm all for living a little, In fact (horror of horrors) I'm even a bit of a risk taker. But not in planes, and definately not with kids/others on board. Different hat.

Your 80kts could be fine, or very slow depending on type. Why as slow as 80kts - faster = more margin. What're the landing options like if the engine coughs, bearing in mind you're going to loose a lot of alt making turns? Just thoughts - my limited experience suggests the more I fly, the more I see traps in places I'd have otherwise sailed through without consideration.

Pilots may seem like a sanctimonious bunch of old grandparents sometimes, but where we go a lot have been before.. and the circling over parents/girlfiriends house is one of THE all time classic ways to go, unfortunately in full view of your loved ones.

englishal
8th Jul 2008, 01:33
Frankly, and this is just my view....If you have a pilot licence and you can't waggle the wings safely, then there is no hope...(few hints: don't stall, don't hit the ground, don't overstress the aeroplane, tell the pax what you are going to do)

tuscan
9th Jul 2008, 12:11
Ive waggled the wings a few times and to be honest I couldn`t give a hoot what it looks like from the ground and spend the whole waggle looking at the dials.
I have to agree with English, if a pilot cant do this safely then questions should be asked.

If you are in doubt get an instructor to go up with you and show you how best to do it safely.

My own advice would be dont spend any time looking at your intended viewers and keep your wits about you in the cockpit, get it over with quickly and concentrate on flying the aircraft.
I have noticed that when taking photos (for example) some of my friends inadvertantly let the airspeed bleed off......:= NOT A GOOD IDEA. and probably more likely in your example.

Shaggy Sheep Driver
9th Jul 2008, 16:16
BackPacker is spot on regarding the incompatibilty between 'looking right' and 'passenger comfort'. Don't do it in a soggy spamcan - it just looks like a wobble, which they do a lot. In a sharper aeroplane, you will need crisp aileron inputs with opposite but co-ordinated rudder to keep straight.

But I, too, wonder why you ask. If you are not absolutely fully conversant with all the issues involved (and if you are not aeros trained and experienced, you might not be, and if you are you wouldn't ask), don't do anything but a gentle co-ordinated turn in alternate directions, ball in the middle.

SSD

Sam Rutherford
9th Jul 2008, 18:16
I was wondering (see original question) if anyone had any techniques to make the waggle more comfortable inside the aircraft, whilst it remaining clearly visible from the ground.

Apparently nobody out there has an improvement on the technique I have been using.

I wasn't expecting a rush of criticism for asking a question! Although PPrune does seem to have more emotion on it than other sites I look in on.

My mistake, perhaps I'll hold short on the questions...

Sam.

Shaggy Sheep Driver
9th Jul 2008, 22:07
Sam... we just want you to be safe. Some of us have seen the result of crossed controls and high angle of attack at low height. It's very quick and very final.

SSD

ShyTorque
9th Jul 2008, 22:25
SSD, I concur.

Crash one
9th Jul 2008, 23:43
I was taught many long years ago "rolling on a heading" in gliders. It is not difficult, but the primary thing here is FLY THE AIRCRAFT & don't try to roll about & wave at Susie at the same time. Didn't someone say that in a Spitfire, if you look somewhere that's where it will go!

englishal
10th Jul 2008, 08:04
There is nothing dangerous about "waggling the wings" ......It is a good exercise in coordination for a start - You look at the nose and bank left and right. With no rudder input the nose yaws opposite to the bank, with the correct inputs it doesn't. It is a very good way to learn to use the rudder properly....

I think you'd have to really manhandle the controls to loose it while waggling the wings (besides you are not cross controlled). The C17's leaving Long Beach - where they're made - usually do a few big waggles on departure.....

robdesbois
10th Jul 2008, 16:08
(...and then maybe have one of the sprogs send her a text message...)

What, from a switched on mobile phone in a light aircraft?? :}

Gertrude the Wombat
10th Jul 2008, 20:14
What, from a switched on mobile phone in a light aircraft??p
Probably OK if VFR, surely, provided you're not relying on a VOR for navigation? And you will be VFR, if doing the circuit-over-girlfriend's-house routine.

Or is there evidence that they interfere with more than just the VHF radios?

On the main point, the message I get is that if I ever feel inclined to want to wing-waggle I'll practice it first at altitude with an instructor on board, then decide whether or not I feel like doing it near the ground on my own.

stickandrudderman
10th Jul 2008, 22:29
Oh ffs!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

BackPacker
11th Jul 2008, 19:22
Or is there evidence that they interfere with more than just the VHF radios?

It's not just that. When airborne you are in line of sight with too many GSM masts and I've heard that this may cause problems because your GSM is trying to contact too many masts at once. Overlapping frequencies, that sort of thing. Apparently to the point where you might bring a whole area down.

I've never seen that proven though.

bjornhall
11th Jul 2008, 19:37
When airborne you are in line of sight with too many GSM masts and I've heard that this may cause problems because your GSM is trying to contact too many masts at once. Overlapping frequencies, that sort of thing. Apparently to the point where you might bring a whole area down.

That is unlikely... What would happen then is that you lower the capacity a tiny bit in the affected cells, which probably won't have a noticable effect for anyone, and that you might lower your own quality of service. If airborne cell phones were more common, cell phone networks would have to be planned based on that, which would require more radio resources for a given area. Therefore, networks operators wouldn't want you to use them in the air. But when it's just a tiny number of GA pilots doing that, I can't imagine this having any effect at all on the cell phone networks.

More modern systems (increasingly sophisticated WCDMA releases, and eventually LTE) are even more resilient to such interference, due to more sophisticated resource scheduling algorithms.

So not a problem there! :ok:

IO540
11th Jul 2008, 20:21
I agree with Englishal - if a pilot cannot do a left/right roll within 20 degrees, completely safely, his PPL should be burnt on the spot.

Obviously one does not do anything like this at Vs+2kt, at 500ft :)

Gertrude the Wombat
11th Jul 2008, 20:36
When airborne you are in line of sight with too many GSM masts and I've heard that this may cause problems because your GSM is trying to contact too many masts at once. Overlapping frequencies, that sort of thing. Apparently to the point where you might bring a whole area down.
I suppose it's possible that if you're high enough and your operator isn't too clever at frequency planning there will be more than one cell within the magic 35km on the same ARFCN.

But ... the cells will have different CGIs and BSICs and so on, and the protocols are designed to cope with this sort of thing, so from what little I know about it (I know the protocol layers but not the RF theory) I don't think there would be a serious problem. For example, your phone should register with the nearest suitable cell, and should then wind down its transmit power to be sufficient for communication with that cell, at which point I would hope it is not causing a problem to any more distance cell on the same ARFCN.

Mobile phones in a light aircraft do interfere with the VHF COM radio, so it seems reasonable to assume that they also interfere with the VHF NAV radio and make sure they're turned off when relying on a VOR for your safety.

if a pilot cannot do a left/right roll within 20 degrees, completely safely, his PPL should be burnt on the spot
I expect that I could do exactly that. But it's not part of the standard PPL course, and I prefer to try new things with an instructor before experimenting on my own. Particularly at 60kt and 500' above someone's house.

VFE
11th Jul 2008, 21:11
A bog standard PPL instructor wouldn't be as useful as an authorised aerobatic instructor, to fully cover the bases of what is essentially a display manoeuvre when you get down to it. When handled correctly it should not present any dangers, but as highlighted by ShyTorque and SSD, the consequences of getting it wrong at low altitude don't bare thinking about so play safe.

VFE.

IO540
11th Jul 2008, 21:54
Maybe I am missing something but one is taught to do turns during the PPL.

I can't remember the angle but 30 deg is certainly taught, and maybe even steep turns.

In the FAA PPL, which I did more recently, you do all this stuff and more. The FAA CPL was actually fun! Chandelles, but I prefer lazy eights...

bjornhall
12th Jul 2008, 07:02
Did I follow this right... Is it suggested you need an aerobatics instructor to teach you to rock your wings?

I seem to recall doing that during my second PPL lesson... I am fairly certain someone must have seen it from the ground at some point. I will hereon refer to myself as "aerobatics display pilot". :E

BackPacker
12th Jul 2008, 07:56
I think the main questions here are:
- What is your speed vs. the stall speed of your aircraft?
- What is your altitude?
- What is the visual acuity of your girlfriend? (In other words, how obvious do your waggles need to be for her to notice?)

If you want to fly a circuit above someones house in your average spamcan, my suggestion would be to maintain 1000' at least (not just for legal reasons) and to maintain something like a reasonable cruising speed, or the speed you fly on downwind (80-90 knots in your average spamcan with a stall speed of about 50 knots).

This gives you enough performance to do a 45 degree steep turn, and this also gives you a reasonable buffer above the stall for a simple wing rock. So a wing rock of up to 20-30 degrees either side, even if a bit out of balance, will not cause any problems. But most likely people doing this will do this in your average spamcan (C172, PA-28 or similar machines) which have the adverse yaw mostly tweaked out of them by things like frise ailerons. So even if you rock your wings rapidly without doing anything with your feet, the aircraft will yaw a bit in the proper direction and keep you in balance. More or less.

So this should be not much safer or more dangerous than doing steep turns up to 45 degrees. (Oh, and of course you remember to add power during steep turns, didn't you? Might be a good idea to add a few hundred RPM when doing wing waggles too.)

But a wing rock like that will look sloppy from the ground because the tail wags as well. The question from the OP was how to prevent that, so that a wing waggle actually becomes an axial roll. For this you need to cross control: a waggle left needs a bit of right rudder. How much depends on the airplane involved, and to what extent the adverse yaw has been aerodynamically tweaked out. Waggles of 45 degrees will also temporarily get you in a sideslip which you may or may not want to counter with a bit of knife-edge flight techniques - which means more opposite rudder. It also need a bit of pushing otherwise your lift vector will take you off course. And all this cross controlling, in addition to being rather uncomfortable for passengers, will rob you of somewhere between 10 and 20 knots of speed - depending on your entry speed, even with full throttle.

So if you're flying in a spamcan with a comfortable speed above the stall (80 vs. 50 knots for instance) and you just roll rapidly left-right to about 20 degrees of bank, without doing anything with your feet (standard for PPL style flying nowadays), there's nothing to worry about.

However, if you want to do the perfect wing waggle, like the one used to denote the start of your aerobatics sequence (45 degrees, three times) you better have a big speed margin above the stall because you're going to lose some speed, and you're going to have to cross-control to keep on the heading. You might also lose some altitude. How to do things like this properly, taking into account rev limits on the engine (if fixed pitch), structural issues like Va and rolling gs, judging 45 degree lines and fuel management (with 45 degrees bank angle, cross controlled, you might not get any fuel to the engine anymore, depending on tank and inlet configuration) is clearly in the aerobatics realm.

liam548
12th Jul 2008, 08:06
I agree, there should be no problems caused using your phone whilst at low speeds and only a couple of thousand feet high.

What causes the issues is when you are over 200mph or so as this is faster than the masts can transfer your signal.

Crash one
12th Jul 2008, 12:32
I suppose I should point out that I have on several occasions circled my house at a 30deg angle of bank, then when my wife waves at me I will waggle the wings with the 30deg bank being the central point of the waggle ie: 30 +& - 20.
No doubt the Nanny state should have something to say about the foolhardiness of such irresponsibility. Do I really have to point out that my airspeed, attitude, altitude, rpm, lookout, location, fuel state, cockpit security, pax state of mental & physical health are all under constant review during the maneuver? And the phones are switched off cos they bugger up the radio!!
If it is possible to "lose it" during landing / take off, engine failure, etc, then adding one more equally sized risk is not going to increase the aggregate to a incalculable level. If the level of risk is of such concern then perhaps we should buy large quantities of bubble wrap & go indoors.:ugh:
On with flak jacket & take cover.

Gertrude the Wombat
12th Jul 2008, 15:23
Oh, and of course you remember to add power during steep turns, didn't you?
Well, there was the time I was a passenger in a sightseeing flight over Glacier Bay and my film ran out. (Before the days of digital cameras.)

"No trouble," said the kid who was doing the flying as a summer holiday job, "I'll hang around here whilst you change the film".

He preceeded to orbit whilst I changed the film. As we were above the ice surface but below the tops of the rock walls this involved a somewhat steep turn. And to keep the turn tight, rather than increase power this kid decreased power quite significantly. "Yeah, well," he said when we were back on the ground, "you have to do that if you want to avoid colliding with the rock. I've had enough training that I won't stall it just by doing a steep orbit with the power off."

BackPacker
12th Jul 2008, 18:56
And to keep the turn tight, rather than increase power this kid decreased power quite significantly.

And you know what... He was most probably right.

In a PPL-style steep turn, which is usually initiated from cruise speed, the objective is not to lose any speed or altitude. Since in a steep turn the g load increases, so does the drag, and to offset this we increase thrust - thus the increase in engine power.

In a tight turn inside a canyon the objective is to decrease the radius. For any given bank angle, the lowest radius can be obtained by flying as slow as possible. So decreasing engine power so the speed decays to just above the stall speed for that bank angle is a good idea.

It is important to realise that this is not the only method of decreasing your radius. You can also maintain speed, up to as high as Va, and roll on the most bank that the aircraft can handle for that speed without getting into an accellerated stall or losing altitude. In a normal category aircraft the smallest radius would either be obtained at Va, with a bank angle of 75 degrees, giving a g load of 3.8, or at 1.4*Vs0, with flaps extended and a bank angle of 60 degrees, giving a g load of 2 - which one it is depends mostly on the difference between Vs0 and Vs1, which is different for each aircraft. And not all aircraft have the engine power to sustain that sort of steep turns, of course.

But I doubt whether you would be able to change your film in such a steep turn and g loading.:eek:

To be honest, I think that your pilot had all these things worked out beforehand: Passenger comfort vs. aircraft ability vs. canyon width. You would not be his first passenger for which he had to do a 360 inside that canyon.

Gertrude the Wombat
12th Jul 2008, 20:56
To be honest, I think that your pilot had all these things worked out beforehand: Passenger comfort vs. aircraft ability vs. canyon width. You would not be his first passenger for which he had to do a 360 inside that canyon.
Yes, I know now that he did it exactly right - but it surprised me at the time! - however I was sensible enough not to ask him about it until we were on the ground.

englishal
13th Jul 2008, 06:57
Maybe I am missing something but one is taught to do turns during the PPL.
It has been dumbed down now in line with everything else. You get an initial "straight line" rating allowing you to fly in a straight line from a to b, after which (100 hrs P1?) you can take the test for "turns rating". This new rating allows you to fly from a to b but not in a straight line :}

Actually I am being facetious as you can probably tell. It does make you wonder though - The FAA PPL includes various "ground reference" manoeuvres, which require coordination and flight often at low altitude, and a newly qualified PPL should in theory be able to do these without stalling, spinning, crashing, etc...(any of the previous leads to an instant withdrawal of the certificate ;)).....

Them thar hills
13th Jul 2008, 10:02
EA
Better not mention slipping turns then .........:bored: