Unexpected flight characteristics
11-14-2013, 04:09 AM
#26
Senior Member
jester_s1's paragraph 1 is spot on. The rudder isn't usually working until it's airspeed comes up. That's usually about the time the tail comes up, right when the tail wheel loses control. The propeller is flying as soon as the plane moves, but the control surfaces aren't in the game until the airframe is close to flight speed.
Your plane taxis under control so use that to your advantage. Get it rolling down the runway and slowly roll in a little throttle, just enough to get the tail rising, then start rolling in throttle as it lifts off.
The left turn on takeoff results from the prop disc pushing through the air at an angle. If you see any left turn you're seeing the prop effect overpowering the airframe. The prop is flying "better" than the airplane. Control the power better and the trouble goes away. Or control the control surfaces better and same thing. Do both and it's easy.
Takeoffs aren't simply power up and go.
Your plane taxis under control so use that to your advantage. Get it rolling down the runway and slowly roll in a little throttle, just enough to get the tail rising, then start rolling in throttle as it lifts off.
The left turn on takeoff results from the prop disc pushing through the air at an angle. If you see any left turn you're seeing the prop effect overpowering the airframe. The prop is flying "better" than the airplane. Control the power better and the trouble goes away. Or control the control surfaces better and same thing. Do both and it's easy.
Takeoffs aren't simply power up and go.
11-14-2013, 08:20 PM
#27
Thread Starter
Join Date: Jul 2004
Location: Cape Town, SOUTH AFRICA
Posts: 579
Likes: 0
Received 0 Likes
on
0 Posts
Hi Jester
Your point number one is very pertinent. I have been corrected after the fact rather than predicting -
I will check the landing gear using two straight edges touching the outside of the tyres and measure the gap and the position relative to the plane centreline., again good point.
Your point number one is very pertinent. I have been corrected after the fact rather than predicting -
I will check the landing gear using two straight edges touching the outside of the tyres and measure the gap and the position relative to the plane centreline., again good point.
11-14-2013, 08:31 PM
#28
Thread Starter
Join Date: Jul 2004
Location: Cape Town, SOUTH AFRICA
Posts: 579
Likes: 0
Received 0 Likes
on
0 Posts
jester_s1's paragraph 1 is spot on. The rudder isn't usually working until it's airspeed comes up. That's usually about the time the tail comes up, right when the tail wheel loses control. The propeller is flying as soon as the plane moves, but the control surfaces aren't in the game until the airframe is close to flight speed.
Your plane taxis under control so use that to your advantage. Get it rolling down the runway and slowly roll in a little throttle, just enough to get the tail rising, then start rolling in throttle as it lifts off.
The left turn on takeoff results from the prop disc pushing through the air at an angle. If you see any left turn you're seeing the prop effect overpowering the airframe. The prop is flying "better" than the airplane. Control the power better and the trouble goes away. Or control the control surfaces better and same thing. Do both and it's easy.
Takeoffs aren't simply power up and go.
Your plane taxis under control so use that to your advantage. Get it rolling down the runway and slowly roll in a little throttle, just enough to get the tail rising, then start rolling in throttle as it lifts off.
The left turn on takeoff results from the prop disc pushing through the air at an angle. If you see any left turn you're seeing the prop effect overpowering the airframe. The prop is flying "better" than the airplane. Control the power better and the trouble goes away. Or control the control surfaces better and same thing. Do both and it's easy.
Takeoffs aren't simply power up and go.
I think alot of the "newer" airframes, extra's, edges etc. only require 30-40 feet to pull themselves into the air on their oversized engines, so takeoffs have regressed to a kind off launch
. As these planes are in the majority at our club there are not a lot of ""takeoff's"" to take example from.Having said that my GP Extra (kit built) get's its tail up quickly and I can roll it down the runway on it's mains until I am ready to leave the tarmac. The slight left yaw after take off is easily corrected.
Bad weather this weekend so probably no flying but I will check the gear alignment and get in some SIM time.
11-15-2013, 07:24 AM
#29
Moderator
When you check your wheels, take into account any wobble that is there. On my Cub, I used 2 yardsticks. One was attached at the fuselage centerline, the other held up tight to the wheel. All wheels have some wobble, so I adjusted the gear so that the ends of the wobble were even from the straight line I was going for. That puts the axle actually straight where you want it. I then put in the slightest amount of toe in to improve the stability a bit. I'm not too sure it actually does much because it is well within the wobble tolerance of the wheels, but it does prevent excessive toe out from happening because of the wobble which probably does help. The hour I used getting the main gear truly set right has paid off in giving me a Cub that is very predictable on ground handling. It will still turn a 90 degree left if I slam the throttle open and don't correct (ie, use bad takeoff technique), which is what a Cub is supposed to do. But it's a consistent left yaw that I was able to learn how to control. There is no yaw change when the tail wheel comes up, and the plane tracks straight on the mains until I'm ready to rotate for takeoff (which also requires a touch of right rudder).
11-15-2013, 07:29 AM
#30
Senior Member
np Andrew
As your Extra has shown, how fast a tail comes up naturally isn't always the deciding factor.
The yaw left is "expected flight characteristics". It happens during the time the nose is pointed up and the prop is flying stronger than the airframe is flying. That length of time depends on a number of things, all of which can be controlled with knowledgeable throttle movement.
Andrew's Extra happens to have an airframe that gets "good grip on the air" about the time the prop's power starts trying to pull the nose left.
The left yaw every tail dragger shows on acceleration is a function of how powerful the prop is versus when the airframe starts "flying". Thankfully, the battle is easily influenced by experienced flyers throttle control. They know that sensible throttle movement at the start of the takeoff roll wins the battle and the war.
As your Extra has shown, how fast a tail comes up naturally isn't always the deciding factor.
The yaw left is "expected flight characteristics". It happens during the time the nose is pointed up and the prop is flying stronger than the airframe is flying. That length of time depends on a number of things, all of which can be controlled with knowledgeable throttle movement.
Andrew's Extra happens to have an airframe that gets "good grip on the air" about the time the prop's power starts trying to pull the nose left.
The left yaw every tail dragger shows on acceleration is a function of how powerful the prop is versus when the airframe starts "flying". Thankfully, the battle is easily influenced by experienced flyers throttle control. They know that sensible throttle movement at the start of the takeoff roll wins the battle and the war.
