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-   -   Elevator position taxiing with tailwind? (https://www.pprune.org/private-flying/547704-elevator-position-taxiing-tailwind.html)

Okavango 16th Sep 2014 21:25

Elevator position taxiing with tailwind?
 
Theoretically I know you're supposed to 'dive away' from the wind though realistically I can't see any wind counteracting the prop wash so much as to affect the nosewheel. What do others generally do?

foxmoth 16th Sep 2014 21:39

This is something that you need to consider in a Taildragger, generally in a nosewheel I would not worry too much unless you were in strong winds or taxiing on bumpy ground in an aircraft that had low prop clearance. Even in a Taildragger you need to think about how strong the wind is - yes, use the aileron appropriately as they are out of the slipstream, but for elevator, in anything less than 15 kts the slipstream will generally overcome the wind, as the wind gets stronger the more this needs taking into account, remembering that as the tailwind gets stronger the less power and slipstream you will have on as the wind pushes you along.

9 lives 16th Sep 2014 23:46

The optimum elevator position will be the one which has the effect you most desire. Of course, in a strong wind, most desirable is the aircraft not being blown over, so if you have the least sensation that could be possible, downwind taxiing is accomplished with the elevator down.

Otherwise, their could be a favourable effect in reducing shock and load on the nosewheel, so if that effect is detectable, use the elevator to raise the nose, and save the nosewheel. There are a few types (Tomahawk, Aztec) where the elevator will not have a noticeable effect during taxiing - so I guess, don't worry about it.

Certain taildraggers may benefit from a bit more down force on the tailwheel for steering, though as many other taildraggers don't care.

Floatplanes are something yet again different.

However, for every tricycle single Cessna I know, which is smaller than a Caravan, holding the nose light, even while taxiing, eases the load on an expensive, and wear prone nosewheel assembly. It irks me no end to see 172's taxied around with the elevator limp, and the nose strut compressed under load. If you're taxiing in a tail wind so strong that the elevator does not have the effect to raise the nose, while held nose up, that's quite a wind - be very careful of the other controls, and for heaven's sake, don't park it downwind in that!

Very simply, keep flying the plane until it is stopped and chocked. If the flight controls are going to improve stability of control, or reduce the chance of upset, use them for that.

Shaggy Sheep Driver 17th Sep 2014 08:23

Taxying downwind in strong winds in the Chippy you can feel if it needs up or down elevator. If the elevator wants to go to either the upper or lower stop due the tailwind, it means the tailwind is stronger than the prop wash, so stick forward to give 'down' elevator so the tailwind blowing on it holds the tail down.

If the elevator wants to trail neutrally, prop wash is stronger than tail wind, so bring the stick back to give up elevator so the prop wash will pin the tail down.

Of course as power setting varies during taxy, you may have to change from one to the other.

One has to be aware on the chippy, taxying downwind in strong winds, not to let the tailwind blow the rudder hard over. That will apply full wheel brake on one wheel which can raise the tail when you're not expecting it. Guess how I know!

9 lives 17th Sep 2014 09:43

SSD has reminded me to mention that while taxiing in a tailwind, hold the flight controls somewhere, don't let them just bang the stops!

dobbin1 17th Sep 2014 12:41

When I taxy the Cub, I stick my hand out of the window to assess the net airflow. Stick fully back unless the net airflow is forward, then elevator neutral.

robin 17th Sep 2014 14:53

We had our taildragger tip over as it turned through the wind bringing in a strong tailwind. A very gentle and totally unrecoverable process once it had started.

The group member in question said later that he tended to hold the stick back being used to the nosewheel approach of stick hard back to relieve weight on the nosewheel and didn't recognise the effect of a tailwind in a sharp turn.

£11.5k bill, though the insurers picked most of that up......

Gertrude the Wombat 17th Sep 2014 18:19

I mostly take the view that if the wind is strong enough that I have to remember the rules then it ain't going to be fun, one way or another, and I fly for fun, so I'm not likely to be flying in those conditions.

Armchairflyer 17th Sep 2014 19:47

@robin
 

We had our taildragger tip over as it turned through the wind bringing in a strong tailwind. A very gentle and totally unrecoverable process once it had started.
Just out of curiosity: tipped over on the nose (prop) or sideways on a wingtip? And which aircraft model?

foxmoth 17th Sep 2014 20:21

Not necessarily unrecoverable but very difficult -
you have two choices - leave the power off and push the stick FORWARD (because the wind is behind you so down elevator with a tailwind may push the tail down). OR:-
Stick back and a burst of power to get the slipstream to "blow" the tail down.

Both of these, especially the second, takes a lot of nerve, plus of course, if you try the second and it does not work, you actually end up doing more damage!

Shaggy Sheep Driver 17th Sep 2014 20:55

Indeed, Fox. A real 'sh*t or bust' situation!

passingnoru 6th Oct 2014 09:17

GUESS
 
There is no special rules thing for elevator usage while taxing.
It mostly about the aileron.
head wind => aileron in to the wind deflection
tail wind => aileron away from the wind deflection

But if the wind if too strong, maybe it'd be better push the yoke forward to improve the ground power. ;)

FrustratedFormerFlie 6th Oct 2014 13:24

Spitmunk QFI summarised his advice to me as 'taxing in a strng following wind? Move the stick in the opposite sense to the throttle." Thottle closed=stick fwd (no sig prop wash, counters risk of tailwind getting under rainsed elevator). Throttle open = stick back to allow prop wash to press tail down, not up.

Seemed OK logic!

3 Point 7th Oct 2014 16:57

"Spitmunk QFI summarised his advice to me as 'taxing in a strng following wind? Move the stick in the opposite sense to the throttle." Throttle closed=stick fwd (no sig prop wash, counters risk of tailwind getting under raised elevator). Throttle open = stick back to allow prop wash to press tail down, not up."

Nice simple way to explain it; that'll be appearing in a tailwheel conversion course near you any day now:ok::ok:

3 Point

Crash one 7th Oct 2014 21:28

Move the stick "downwind" simples. If the "wind" is created by the prop then pull, if it is windy on the tail taxiing slowly then push.
Same applies with aileron, if the wind is from a rear quarter move the into wind aileron down. If the wind s from ahead left or right, fly the aircraft!

Unusual Attitude 8th Oct 2014 14:09

As SSD states you can usually 'feel' what’s going on at the back end with regards from which direction the airflow is the most dominant.

The point I hate is when your 'expediting' a backtrack in a hurry with a strong tailwind and you feel the elevator go light just as you need to think about chopping the throttle and hitting the brakes!!! :ooh:

FrustratedFormerFlie 8th Oct 2014 14:41

Re 'you can feel what's going on', I'm nervous about that. By the time you can feel it, it's getting to be too late - which is why 'rules of thumb' are useful.

Imagine an early tailwheel conversion solo. The 'lard' has got out of the back seat, so she's that bit more 'tail happy'. Bloggs feels the tail lighten. Stick is already back. Due to inexperience, Bloggs opts for the most immediately accessible thing he thinks he can change - speed - applies the brakes in search of a feeling of more control, and ends up with the prop in the dirt instead.

There but for the grace of God....

Unusual Attitude 8th Oct 2014 15:01

I was talking about personal experience on a type I have a lot of time on, not as a newly qualified Bloggs since the OP was asking what others do.

To be honest with taildraggers there are no hard and fast rules, what works well on a Supercub might well cause you to bend a Cassutt / Pitts. You should however still be able to 'feel' whats going on in any type....

Regards

UA

Crash one 8th Oct 2014 17:08

A few weeks ago I landed in a 45deg crosswind, turned into wind 180deg & wasn't quite quick enough getting the stick forward. Tail came up to about level, slammed the stick forward & closed throttle & caught it in time, but it does take conscious think which way to push things in a hurry. It is easy to be smug arsed & make suggestions but hard & fast "methods" don't always work. I once spun it round a bit quick in no wind & tail came up, closed the throttle and back stick feet off brakes worked that time. Difficult to lay down "rules".

Shaggy Sheep Driver 8th Oct 2014 18:48

Crash one, if you haven't thought through the various scenarios in advance and come up with a strategy ('rules' in your words) how are you going to know what to do if 'X' happens under 'Y' circumstances?

'Winging it' is not the best plan. In fact 'winging it' is no plan at all, it's "oops, sh1t, wasn't expecting that, so I'll try this and see what happens".

Recipe for disaster, that is.


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