Tailwheel takeoff - best side for crosswind?
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Tailwheel takeoff - best side for crosswind?
A couple of weeks ago I landed my Jodel D120 on a grass strip with a slight crosswind. No problems - straight down the centreline to then park and have a cup of tea. On leaving, the wind had shifted to a right angle crosswind from the left and increased to that the windsock was nearly horizontal.
The runway direction had not changed so, with into wind elevator down and right (edited - I had typed left) rudder applied as standard, I gently started the takeoff run and slowly rotated to the left as I weathercocked due to the wind against the fuselage. A short crosswind runway was available and I was allowed to leave on that.
Here's my question:
As a tailwheel has a tendency to turn left, I think that, were the crosswind runway not available, I'd have been better to take off in the opposite direction with the crosswind coming from the right hand side. Then it would have been easier to counter the crosswind.
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Thoughts and comments? All part of the learning process!
The runway direction had not changed so, with into wind elevator down and right (edited - I had typed left) rudder applied as standard, I gently started the takeoff run and slowly rotated to the left as I weathercocked due to the wind against the fuselage. A short crosswind runway was available and I was allowed to leave on that.
Here's my question:
As a tailwheel has a tendency to turn left, I think that, were the crosswind runway not available, I'd have been better to take off in the opposite direction with the crosswind coming from the right hand side. Then it would have been easier to counter the crosswind.
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Thoughts and comments? All part of the learning process!
Last edited by rusty sparrow; 3rd Sep 2011 at 11:37. Reason: typed LEFT rudder, should have typed RIGHT rudder to make sense.
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Lord SM has it! Surely a Jodel requires right rudder on take off, assuming it has an American flat 4 engine? A x-wind from the left will call for more right rudder than usual, one from the right for less right rudder than usual.
In our Chippy, of course, it's the other way around.
In our Chippy, of course, it's the other way around.
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You're right, sometimes with a left crosswind the added swing left from the prop gyro effect can get you into the long grass. It definitely is easier with a right crosswind (prop running anticlockwise from the front).
I've recently tried a different technique which seems to work well in our Jodel DR1050. The gyro effect is greatest when lifting the tailwheel. I find the aircraft is equally happy taking off without raising the tailwheel - just hold the stick slightly back until you unstick. It tracks straighter with the tailwheel on the ground.
I've recently tried a different technique which seems to work well in our Jodel DR1050. The gyro effect is greatest when lifting the tailwheel. I find the aircraft is equally happy taking off without raising the tailwheel - just hold the stick slightly back until you unstick. It tracks straighter with the tailwheel on the ground.
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"As a tailwheel has a tendency to turn left,..."
Er - No!!!
The tendency depends on which way the engine turns! Nothing to do with a tailwheel, tricycle or otherwise.
If you fly something with an engine which runs the other way - and some do - the yaw tendency will be opposite, regardless of undercarriage configuration.
Er - No!!!
The tendency depends on which way the engine turns! Nothing to do with a tailwheel, tricycle or otherwise.
If you fly something with an engine which runs the other way - and some do - the yaw tendency will be opposite, regardless of undercarriage configuration.
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If the engine torque effect and crosswind both conspire to work against you (as I understand your initial post to read), you should have enough rudder authority to combat it as long as you are ready for it. Once the swing starts you bare fighting a losing battle. As younfeed the power to full, have some rudder feeding in at the same time.
Also, in these circumstances, if you try and get your tail up as early as you would on a normal take-off there is an increased chance of the tail swinging round as the tailwheel leaves the ground. One way of dealing with it is to hold the tail down for a little longer than normal on the take-off roll. This reduces the chance of any early weather-cocking and when you do bring the tail up, your forward airspeed (combined with the ongoing prop thrust) will mean that your rudder authority will be powerful enough to control the weather-cocking more easily.
In really strong crosswinds, I sometimes go for a three point departure to guarantee no swinging around with the tail in the air. Just be careful if the strip is bumpy as it can hammer the tailwheel and spring though.
Also, in these circumstances, if you try and get your tail up as early as you would on a normal take-off there is an increased chance of the tail swinging round as the tailwheel leaves the ground. One way of dealing with it is to hold the tail down for a little longer than normal on the take-off roll. This reduces the chance of any early weather-cocking and when you do bring the tail up, your forward airspeed (combined with the ongoing prop thrust) will mean that your rudder authority will be powerful enough to control the weather-cocking more easily.
In really strong crosswinds, I sometimes go for a three point departure to guarantee no swinging around with the tail in the air. Just be careful if the strip is bumpy as it can hammer the tailwheel and spring though.
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On leaving, the wind had shifted to a right angle crosswind from the left and increased to that the windsock was nearly horizontal.
If you had a 90 degree, full sock crosswind and an american engine airplane then you perhaps learned your lesson on this day out. Nothing broken and hopefully something learned. While pilots getting in on tailwheel airplanes feel more comfortable side slipping to the left, the reality of it is that a taking a crosswind on from the right hand side offers alot more options*. Indeed ask someone to do an aileron roll, and most will go left. A 25kt right hand crosswind is not a big deal in the Cessna tailwheel I fly, as one large application of power straightens the aircraft.
Presuming the basics are right then you can practice this all day, just air taxing up and down the runway on one wheel. If you want the level of competency that truly makes xwinds a non event, just go out and get that trick right!
* American engine assumed
If you had a 90 degree, full sock crosswind and an american engine airplane then you perhaps learned your lesson on this day out. Nothing broken and hopefully something learned. While pilots getting in on tailwheel airplanes feel more comfortable side slipping to the left, the reality of it is that a taking a crosswind on from the right hand side offers alot more options*. Indeed ask someone to do an aileron roll, and most will go left. A 25kt right hand crosswind is not a big deal in the Cessna tailwheel I fly, as one large application of power straightens the aircraft.
Presuming the basics are right then you can practice this all day, just air taxing up and down the runway on one wheel. If you want the level of competency that truly makes xwinds a non event, just go out and get that trick right!
* American engine assumed
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Thanks for all the comments - learning to fly a tailwheel is very rewarding but sometimes challenging 
Yes, I meant a clockwise rotating propellor (from pilots view). So, in that case there are several forces that will cause the tendency to turn left.
I also fly a Jodel D9 with a tailskid and no brakes - that's fine in crosswind takeoffs but tricky to taxi. In contrast, the Jodel D120 with castoring tailwheel and brakes is easy to taxi but more of a handful in a crosswind takeoff.
I always find turing to the left and slipping to the left more natural - so Irish Seaplane's comments are worth remembering. And, yes, I know which side to have the crosswind from when I next have this situation.
Didn't know that about the cub overun - I've only got a couple of hours in cubs and never had a strong crosswind to deal with.
Yes, I meant a clockwise rotating propellor (from pilots view). So, in that case there are several forces that will cause the tendency to turn left.
I also fly a Jodel D9 with a tailskid and no brakes - that's fine in crosswind takeoffs but tricky to taxi. In contrast, the Jodel D120 with castoring tailwheel and brakes is easy to taxi but more of a handful in a crosswind takeoff.
I always find turing to the left and slipping to the left more natural - so Irish Seaplane's comments are worth remembering. And, yes, I know which side to have the crosswind from when I next have this situation.
Didn't know that about the cub overun - I've only got a couple of hours in cubs and never had a strong crosswind to deal with.
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Whilst the engine rotation determines the direction of the swing, the wheel configuration does add gyroscopic procession to the picture as the tail comes up - if that's at the wrong moment it can be the extra straw.. But frankly I'd request the different runway every time.
I'd always assumed the reason everyone rolls left is 'cos everyone teaches it to the left
The theory advanced at the time was that the prop 'helps' the roll.
I'd always assumed the reason everyone rolls left is 'cos everyone teaches it to the left
The theory advanced at the time was that the prop 'helps' the roll.
any gusts will make it more of a headwind as the wind direction veers.
Pull what gives sound advice. We had a big left crosswind at Harris Hill today. I was towing in the Pawnee. I don't care which way the propeller spins, the key thing is not running out of rudder. We only had about 10 kts direct crosswind so it was not too bad. If it is bad enough that you need a right crosswind versus a left crosswind to not run out of rudder, leave it tied down!
In the cub with a left crosswind I don't use flaps at all.
-- IFMU
In the cub with a left crosswind I don't use flaps at all.
-- IFMU
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At an airshow at Rougham some time back I was watching a display by a well known Yak . The commentry is I believe given by his partner .
She emphasised on take off that the engine on the Yak turns the opposite way to " EVERY " other aircraft !
I wonder what direction he takes on a stiff cross wind?
She emphasised on take off that the engine on the Yak turns the opposite way to " EVERY " other aircraft !
I wonder what direction he takes on a stiff cross wind?
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A question posed by one of the (trickier) instructors at my club:
The answer he's looking for:
Which way does a Tiger Moth swing during takeoff?
The answer he's looking for:
It doesn't - because you taught me to do it correctly.
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IFMU, l can well understand that with the Cub. The only aircraft l failed to like, with not one redeeming feature, despite it`s cub wings, was the pawnee.
ln a limited space the difference between floating and getting on the back of the drag curve, and arriving like a sack of sh** was about 7kts.
Off thread, sorry.
ln a limited space the difference between floating and getting on the back of the drag curve, and arriving like a sack of sh** was about 7kts.
Off thread, sorry.
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Brian Lecomber wrote some excellent articles for PILOT magazine in the UK some (nearly 30 years ago
).
He very accurately described the four forces that conspire against taildragger pilots from keeping to the straight, and hopefully not too, narrow.
Propellor blade rotation direction is the most visible. Clockwise, from the cockpit is as most have already written, mainly american based engines. Anticlockwise tends towards older, antique, british engines. The force generated is due to torque. Turn the prop clockwise, and the fuselage will want to rotate anticlockwise. This will put more weight, and therefore drag from friction on the left mainwheel, and turn the nose to the left. Right rudder needed to track straight.
Next is assymetric blade effect. Because the fuselage is tail low, the thrust line of the engine is tilted nose up. This gives the down going blade a greater angle of attack than the up going blade. The thrust line of the propellor is therefore moved from the prop. centre line to the side where the prop. is going down. In the case of a clockwise engine, this will move the nose to the left. Right rudder needed to track straight.
Now comes propwash. The propwash doesn't go sraight back ove the fuselage. Because the prop is rotating, so is the propwash. It therefore hits the fin and rudder at an angle, cusing a yawing moment. If again the prop turns clockwise, it will hit the right side of the fin, causing the nose to move to the left. Right rudder needed to track straight (notice anything yet?).
Finally gyroscopic precession. The spinning prop has some properties of rigidity, as in a spinning gyroscope. We start of with the prop. disc tilted, nose up. When we raise the tail during the take off run, we effectively apply a force to the top of the prop disc to tilt it to the vertical. The results in a movement of the disc, 90 degrees later. In a clockwise (last time) spinning prop this means the nose will swing to the left. Right rudder needed to track straight.
All these four forces are additive, and are at there strongest at high power settings and low airspeeds. Your only balance control against them is the rudder, which is least effective at low airspeeds and tail down, blanketed by the fuselage.
Clockwise turning engines means you have significant RIGHT rudder applied, before any crosswinds are taken into account. Crosswind from the left merely adds to the mix.
Short coupled aeroplanes, castoring tailwheels which can't be locked, high power engines, big (heavy) propellors, high nose high angles, smooth tarmac or short grass, healthy crosswinds, putting power on too quickly, raising the tail too early, inexperience or lack of currency on type, all add to a spectators entertainment. Enjoy
).He very accurately described the four forces that conspire against taildragger pilots from keeping to the straight, and hopefully not too, narrow.
Propellor blade rotation direction is the most visible. Clockwise, from the cockpit is as most have already written, mainly american based engines. Anticlockwise tends towards older, antique, british engines. The force generated is due to torque. Turn the prop clockwise, and the fuselage will want to rotate anticlockwise. This will put more weight, and therefore drag from friction on the left mainwheel, and turn the nose to the left. Right rudder needed to track straight.
Next is assymetric blade effect. Because the fuselage is tail low, the thrust line of the engine is tilted nose up. This gives the down going blade a greater angle of attack than the up going blade. The thrust line of the propellor is therefore moved from the prop. centre line to the side where the prop. is going down. In the case of a clockwise engine, this will move the nose to the left. Right rudder needed to track straight.
Now comes propwash. The propwash doesn't go sraight back ove the fuselage. Because the prop is rotating, so is the propwash. It therefore hits the fin and rudder at an angle, cusing a yawing moment. If again the prop turns clockwise, it will hit the right side of the fin, causing the nose to move to the left. Right rudder needed to track straight (notice anything yet?).
Finally gyroscopic precession. The spinning prop has some properties of rigidity, as in a spinning gyroscope. We start of with the prop. disc tilted, nose up. When we raise the tail during the take off run, we effectively apply a force to the top of the prop disc to tilt it to the vertical. The results in a movement of the disc, 90 degrees later. In a clockwise (last time) spinning prop this means the nose will swing to the left. Right rudder needed to track straight.
All these four forces are additive, and are at there strongest at high power settings and low airspeeds. Your only balance control against them is the rudder, which is least effective at low airspeeds and tail down, blanketed by the fuselage.
Clockwise turning engines means you have significant RIGHT rudder applied, before any crosswinds are taken into account. Crosswind from the left merely adds to the mix.
Short coupled aeroplanes, castoring tailwheels which can't be locked, high power engines, big (heavy) propellors, high nose high angles, smooth tarmac or short grass, healthy crosswinds, putting power on too quickly, raising the tail too early, inexperience or lack of currency on type, all add to a spectators entertainment. Enjoy