Tailwheel - wind behind you
 

I am canvassing others thoughts and opinions on this, in particular with regards to very light tailwheel a/c. (Such as the ALMS Savage but any similar light, tailwheelers)

Where should the stick be with the wind behind you?
With the engine running and taxying, obviously there's propwash over the tail - but you've got the wind behind you also?

How strong a wind would it need to be to overcome the propwash?

Depends on how tippy the plane is and the strength of the wind, but generally I'd have the stick slightly forward of neutral, never fully back

In general with the dozen or so tailwheel types I've flown (but don't even know what an ALMS Savage looks like), then when taxiing downwind tend to keep elevators neutral if the wind is above anything light (5-10kts).

How light a tail is the Savage? It's difficult to give hard and fast rules. And beware of bar-room pundits! Some tailwheel aeroplanes sit so heavy on the tail that you have to push the stick forward with power to lighten the tailskid to get a turn started.

Perhaps think as you go of how much power you are using. If on a smooth tarmac taxiway with little power needed then you are getting little propwash. However uphill on a grass surface, then you've got quite a bit of propwash.

You could even try a test. Position the aeroplane facing downwind ( a reasonable wind), chocked and with a restraint to stop the tail rising, then try moving the stick to see what effect it has.

I was taught during my conversion that 10kts+ would be enough to counteract the prop's flow and to simply centre the stick in such cases. This applies to Cubs.

Hold it neutral and 'feel' for wind effects. If tailwind is stronger than the propwash, the elevator will tend to be blow to full up or full down, and you'll have to hold it positively neutral. If Propwash greater than tailwaind, elevator will tend to trail just below neutral (depending on weight bias of the system in no-wind conditions, and assuming you don't have one of those horrid spring-bias elevator 'trims' (Tiger Moth??) which just hides from your hands what is really going on back there).

As you vary the power and position relative to the wind as you taxy, you might find you have to sometimes let it trail and sometimes hold it positively neutral.

Someting to be aware of in the Chipmunk in a strong tailwind is the rudder. If you have a notch or two of brake set and you get a sudden strong gust from behind, if you're not bracing the rudder with your feet, it can get blown to full deflection, thus applying one wheel brake sharply, and lifting the tail - ideal conditions for a nose-over. :(

SSD

Have no experience of the Savage but...
Have you ever tried lifting the tail of a taildragger? After having tried it you should then imagine the effect of your weight, and then imagine how strong the wind would have to be to lift the tail.

By the time the wind gets that strong you'll probably be having problems crosswind and your aircraft should be safely tied down or in a hangar.

Appreciate also that the inverted v of the tailplane with the stick fully back makes a rough airfoil section which would produce a down force if it had any appreciable effect.

Good practice, however, dictates that the stick should be neutral or just forward of neutral so that the effect on the top surface maintains a down force or the propwash doesn't create a significant up force.
This is as much to maintain directional control as to keep the tail down.

The first symptom of insufficient tail down force will be reduced directional control. Some tailwheels require lifting to get them to castor.

The Savage is a J3 cub look alike microlight:

http://www.alms.fr//images/galerie/savage/01.jpg

The ALMS Website has all you need to know, assuming your french is up to scratch :)

Brooklands

Miserlou, I hear what you're saying BUT.........

Ever tried lifting the tail of a Super Cub? Pretty heavy even if you have biceps like Schwarzeneggar. But I have seen two tipped forward onto their nose by a tailwind, which was not that strong, maybe 10-15kts. The pilot was taxying downwind with aft stick. I also once saw 2 Turbulents tip onto their noses at the same time as they both turned downwind to depart, in a fairly brisk, but not overly strong wind. A formation tip-up!!! Fortunately with little damage:{

As always, experience will tell you when to leave it in the hangar and have a beer instead...:ok:

Don't be mislead by how difficult it is to physically lift the tail. It takes two hefty blokes to lift a Chipmunk's tail off the ground, and while it's one of the more tail-heavy taildraggers, I've thad the tail lift more than once in strong tailwinds (and got it down again!), once through that rudder thingy I mentioned in my earlier post. Try lifting your pride and joy off the ground when she's in the hangar - can't be done. But 40 or so knots under the wings and up she goes. ;)

Always treat strong winds on the ground with great respect when taildragging, at all times that you are not facing directly into it.

SSD

Can I ask how? Is it stick fully forward? Or the alternative I imagine is a burst of power and stick back? As somone mentioned on grass, uphill using forward stick goes against all my senses.

Forgive my cynicism but in my experience, personal and indirect, I haven't seen any incident due to the tailwind alone; there have always been other factors such as soft ground, use of brakes and such like.

I failed to mention the fact that the effect of the wind on the wings, that is above the c of g, also adds to the nose forward effect. Perhaps if operating in such conditions, one should avoid having the tail into the wind.

Incidentally, I have also seen two characters walking their Tigers; useful especially when on tarmac.

Zlin,
The Turbs sound like a John Martin-Hale party trick.

quote:
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I've thad the tail lift more than once in strong tailwinds (and got it down again!)
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Ah! The golden question! Either might work, and either might result in tears. The Chipmunk is a tail-heavy taildragger, and that's why I probably got away with it. Can't remeber how I got it down - probably stick back and power - there isn't time to think, you just do what feels best.

In a tail-light aeroplane, I think if the tail comes up unintentionally, it could be very difficult to get it down again. If you pull the stick back and bang on full power, it's sh!t or bust - it's probably the best way to get the tail down again, but if it fails and she goes over, it could be quite spectacular and quite expensive, too. :eek: And don't forgrt I'm talking about wind-induced nose-overs (both mine were on the apron, on concrete). As Miserlou said, most nose-overs occur on grass and there's probably an element of the wheels sinking in. In that case, the last thing you want to do is put on power. ;)

There's no simple answer, I'm afaraid.

The best method, and the one I try to stick with these days, is to keep that tail on the ground in the first place. :ok:

SSD

TC450,
if you think about it, if the nose starts to go over in a strong tailwind, then it's either due to the tailwind acting under the elevator (most likely), or the prop pulling against some wheel resistance (e.g. soft ground).
If you increase power in the latter case, it'll potentially make things worse, even if you pull back on the joystick (as the tail-down elevator forces may be far less than the increased turn-over forces created by the difference in the prop thrust coupled with the wheel drag). And if it's the former case, a power increase with elevator up only MIGHT work (depending on how much thrust you can develop, how effective your prop wash over the elevator is, strength of tailwind etc.), but elevator forward whilst cutting power (assuming you don't have it fully forward already), will dump the downwind induced tail lift, avoid increasing tail lift through propwash, and down she'll go again....a far safer option ......
A

Unfortunatly, it ain't that simple. If the tail has lifted beyond a few inches, the tailwind will act on the underside of the elevators and, on taildraggers with flat undersides to their fuselages (very many - Cubs, Citabrias, Furys, Vagabonds, Maules - loads of 'em .....but not Chipmunks) the wind will act on that as well. This will all tend to blow the aeroplane onto its nose, and holding forward stick and removing power is unlikely to prevent it.

As I said, the best thing is to ensure the tail never lifts unintentionaly in the first place. If it does, it's probably too late to do much about it in most aeroplanes, especially if on grass where wheel 'sticktion' is probably a factor. On tarmac, the 'stick back and full power' method may save you, but if it doesn't it could be expensive.:(

SSD

I asked a similar question of my (very experienced) tail-dragger instructor a couple of years ago, in a PA18. Whilst taxying along with a tail-wind (I think it was about 15kt), he suggested I stick my hand out of the window. As soon as I felt the relative airflow on my hand it was obvious that the combination of forward movement of the aircraft and the propwash resulted in the relative wind coming from in front of the aircraft, therefore the stick was held back in this case.

FFF
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FFF,

Yes, my instructor gave me the same tip. I had completely forgotten it, thanks for reminding me :ok:

I would be wary of assuming that the wind on your hand when you stick it out of the window is necessarily the same as the wind under your tail. That doesn't seem to follow at all. This sounds like an old wives' tail to me.

QDM

QDM, why's that?

I could see that you might have a point for an aircraft with its tail in the air, where the underneath of the aircraft would be subject to a tailwind, and would be blanked off from any oncoming air from in front of the aircraft (as someone has already described).

But if the tail is firmly on the ground, the only parts of the rear of the aircraft which will be subject to any airflow are shaped in such a way that the air in front of them, where your hand is sticking out, will be roughly the same as the air passing over those surfaces, are they not?

Having said that, I've never tried taxying a tail-dragger in challenging winds, so my theories and second-hand wisdom will definitely take second place to people with more tail-dragger experience. But I'm curious to know if I'm wrong, and why I'm wrong.

FFF
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The hand-out-the-window method may or may not work - but what matters is the airflow over the tail, so I refer to my earlier post - feel it through the stick. A tailwind that is stronger than the propwash will tend to push the elevator up or down.

SSD

There must be some point at which the tailwind counteracts the propwash. If that happens to occur between your window and the tail, you will have forward wind on your hand and backward wind on the tail.

QDM