Flying the perfect wing waggle!

[stickandrudderman]

Oh ffs!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[BackPacker]

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]

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!

[IO540]

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]

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]

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]

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]

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".

[BackPacker]

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]

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]

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.
On with flak jacket & take cover.

[Gertrude the Wombat]

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]

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.

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]

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]

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]

Too hard box

EA
Better not mention slipping turns then .........