toe in
09-22-2008, 05:37 AM
#26
RE: toe in
Forgot to add that in theory and practice for me toe out accentuates a nose down down tendency under takeoff power with the tail up.Not bad in windy conditions.
12-26-2008, 11:07 AM
#28
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RE: toe in
ORIGINAL: Flyboy Dave
I've been flying Cub's for over 35 years. They can be the hardest of all
planes to take-off if the wheels are not set correctly....it's just the way they are.
With the wheels set the way I described, they set up an equal amount of drag.
If you have ever taken a skiing lesson....the idea is the same as the "snow plow"
technique...where the skies are tilted and pointed inward to gain stability.
If you want to see a totally uncontrollable Cub....set the wheels perfectly straight "up",
then turn both wheels "out" just a tad....
....you will find out what a ground loop is all about.
Take-off tips I have been successful with:
Only use 1/2 throttle until you pull the plane off the ground, then apply more throttle.
Start the take-off roll out with 1/2 right rudder applied, and full up elevator for the first
15 or 20 feet. The "right rudder" and keeping the tail wheel on the ground will keep the
plane from veering to the left from th prop/engine torque. Some right thrust in the engine
is always desirable with a Cub as well.
Once the place rolls the 15 to 20 feet, release the elevator and allow the tail to come
off the ground. At this point you should have enough speed so the rudder will be effective.
Release the right rudder as the plane starts to move to the right...keep the right applied
until this happens. The trick is having the correct amount of steering (rudder) and the correct
amount of throttle to keep the plane going straight until the speed is right for take off.
Increase the throttle very gently as the plane lifts off...and don't lift off until you have some
decent speed.
I think one of the reasons I've always had a Cub is because they are challenging to fly. My
last one was a built up clipped wing Goldberg Anniversary Cub with a Magnum .91 four stroker
in it. I had it for about 15 years, and sold it to a friend who wanted it. It was built like a tank.
I have a new kit in the pile....I must build it soon.
FBD.
I've been flying Cub's for over 35 years. They can be the hardest of all
planes to take-off if the wheels are not set correctly....it's just the way they are.
With the wheels set the way I described, they set up an equal amount of drag.
If you have ever taken a skiing lesson....the idea is the same as the "snow plow"
technique...where the skies are tilted and pointed inward to gain stability.
If you want to see a totally uncontrollable Cub....set the wheels perfectly straight "up",
then turn both wheels "out" just a tad....
....you will find out what a ground loop is all about.
Take-off tips I have been successful with:
Only use 1/2 throttle until you pull the plane off the ground, then apply more throttle.
Start the take-off roll out with 1/2 right rudder applied, and full up elevator for the first
15 or 20 feet. The "right rudder" and keeping the tail wheel on the ground will keep the
plane from veering to the left from th prop/engine torque. Some right thrust in the engine
is always desirable with a Cub as well.
Once the place rolls the 15 to 20 feet, release the elevator and allow the tail to come
off the ground. At this point you should have enough speed so the rudder will be effective.
Release the right rudder as the plane starts to move to the right...keep the right applied
until this happens. The trick is having the correct amount of steering (rudder) and the correct
amount of throttle to keep the plane going straight until the speed is right for take off.
Increase the throttle very gently as the plane lifts off...and don't lift off until you have some
decent speed.
I think one of the reasons I've always had a Cub is because they are challenging to fly. My
last one was a built up clipped wing Goldberg Anniversary Cub with a Magnum .91 four stroker
in it. I had it for about 15 years, and sold it to a friend who wanted it. It was built like a tank.
I have a new kit in the pile....I must build it soon.
FBD.
I did some research and found that many full scale pilots recommend toe out for taildraggers too. They even mention that some cars have toe out too. http://www.mombu.com/aviation/aviato...n-1400001.html Post #8 in this thread http://www.rcuniverse.com/forum/m_48.../tm.htm#488183 said that toe out worked on his narrow geared spitfire.
I don't think that the above analogy of a snowplowing skier is good because skiers can shift their weight around (fore and aft and left and right) thus changing the steering qualities of their "wheels" in a way that airplanes can't. The inward pointing of the skis is mainly done because the inward pointing skis force the knees against each other and requires less muscle strength to hold that position than outward pointing skis. As with my diagram below, the skier's direction is based on the ratio of weight on each ski. In a plow, the skier can go left by putting more weight on the right ski.
12-26-2008, 08:22 PM
#29
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RE: toe in
ITS ALIVE, ITS ALIVE again.
Hi thought this was dead, have not seen it for awhile.
The cubs are the only RC plane I have had a problem with, as fare as the ground handleing and this toe-in vs. toe-out. It had been years sence I put a .40 size cub together and I overlooked the toe-out of the wheels. I could not do a run for take off without ground loops and the landings were no better. I found myself applying full power and pulling it off the ground as quick as I could.
But after the input above and putting toe-in into the main gear, the plane turned into a great handleing plane on the ground. I even let it track with the tail in the air for 20 to 30 feet on landings without a problemI really started to enjoy flying it, and how others do it is of no matter to me.
Like RC KEN said the cub was the hard to handle on the ground, and I have to agree. But if set up right they are not that bad.
sticks
Hi thought this was dead, have not seen it for awhile.
The cubs are the only RC plane I have had a problem with, as fare as the ground handleing and this toe-in vs. toe-out. It had been years sence I put a .40 size cub together and I overlooked the toe-out of the wheels. I could not do a run for take off without ground loops and the landings were no better. I found myself applying full power and pulling it off the ground as quick as I could.
But after the input above and putting toe-in into the main gear, the plane turned into a great handleing plane on the ground. I even let it track with the tail in the air for 20 to 30 feet on landings without a problemI really started to enjoy flying it, and how others do it is of no matter to me.
Like RC KEN said the cub was the hard to handle on the ground, and I have to agree. But if set up right they are not that bad.
sticks
12-27-2008, 07:54 AM
#30
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RE: toe in
It's possible that the Cub is a special case where toe in is needed. That Spitfire in the link that I posted benefited from toe out, though. I don't know what the factor would between the Spit and the Cub that would make the difference. The biggest difference between the Cub and a Spitfire is the Cubs higher dihedral effect. Other comments in this thread suggested that toe in is always needed for every airplane. My experience with my H9 corsair and the full scale forum that I linked to tell me otherwise. So, I just thought I'd present the reasoning for possibly using toe out. I didn't mean to come across as telling you that you are wrong about your Cub. In the full scale forum there was a comment to the effect that toe angle can't fully compensate for bad technique. So, toe angle may be made irrelevant by poor technique in some cases. Also, there may be a gray area when toe angle preference may be entirely dependent on the pilot's technique habits. In other words, both toe in and toe out may have their plusses and minuses and the pilot uses whichever toe angle that they got comfortable with first.
12-27-2008, 10:14 AM
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RE: toe in
I have always put toe-in into the mains of my taildraggers and trikes. I noted that the wire main gear tended to "wear" to give toe-out, so I would keep bending things to toe-in after many landings. My aluminum gear would likewise go to toe-out with usage. About 3 years ago I built a SPAD 72" WS J3-Cub with an OS46FX engine and 12X4 APC prop. It uses a carbon reinforced fiberglass gear that keeps the wheels neutral, ALWAYS. The angles do not change with usage. I have stopped worrying about the toe-in/toe-out problem. Maybe it is because it is NOT adjustable by bending the gear. I see nothing in the performance to indicate to me that toe-in/toe-out is needed. I am always amazed at how difficult the J3-Cub is to take off and land. That is probably why I like it so much. Do it perfect or it will let you know. I loved that carbon reinforced fiberglass gear so much that I used it to replace the 3/16 diameter wire gear I was using on my SPAD OS46FX size Pusher Canard. That plane lands hot on the mains and the new gear works perfect. So, neutral, if it stays neutral under load and usage, seems to work great for me. In my opinion, if toe-in or neutral goes to toe-out under load/usage, then there can be difficulties.
