Twisted Stick October 2007 Newsletter

Just for fun this month I thought I'd talk about taking off a tail dragger.

When I was a brand new member my father-in-law Dick and I built a Great Planes ARF.  It was a Cub powered by an OS FS 70 II surpass.  We were really proud of this plane especially Dick.  He had a love of Cubs since his first ride in one at the grand old age of ten.  This model really reminded him of that Cub. 

Man were we proud - we had even figured out how to plumb the fuel tank properly.  Those instructions that seem so clear now certainly weren't then.  The plane was Dick's pride and joy.

He was going to use it for his trainer, as the original that he flew in and had piloted was so gentle.  Fortunately cooler heads at the club prevailed and talked him out of flying it.  As I remember Ken McFarland was instrumental.  Dale clinched the deal by selling him a SIG LT40 ready to fly.  As I know now he sold it to Dick at a cost below what he had in it.  Considerably below actually but that's Dale always willing to help someone out.

Dick and I were both just learning how to fly and we both knew we had no business trying to fly the Cub.  So we dragooned a member into doing the maiden honors.  The first flight take off was just about a disaster but at the last moment the Cub clawed it's way into the sky.  Dick was in a state of almost rapture watching his cub. 

He wanted to see it fly again and the member reluctantly agreed.  He thought that perhaps the problem with the first take off was the size of the motor so he would keep the rpms down.  The next take off saw the plane lifting about six feet off the ground and turning the wing tip into the ground and cart wheeling down the runway.  I thought Dick wanted to cry and the guy doing the flying didn't feel any better either.

Dick took it home and repaired it.  A new cowling, windshield and repair to the wing tips and it looked good as new.  This time Dick took it to one of the more experienced club members.  He said the way he takes off is to bring it up on throttle as quickly as possible while controlling the rudder for a short take off.  Sounded good, but it didn't work out so well though, another cartwheel on take off. 

This time when he repaired it Dick left on an old bondo filled cowling and a glued up windshield.  The new ones he left in their boxes.

Now what I've failed to mention before now is that Dick had videotaped these takeoffs.  We spent quite few evenings watching the takeoffs and what we finally saw in all of them was the tail came up just as the plane attempted to takeoff. 

I had been using the Internet reading on RC Online that a Cubs tail will come up before the wing is ready to fly.  And that if you attempted to take it off before the wing had reached flying speed the wing would stall resulting in a cart wheel down the run way.  The author recommended building up take off speed gradually feeding in some right rudder and letting the tail come up while the main wheels were planted firmly on the ground and then taking off at a gentle glide slope.

Well Dick wasn't going to let me take it off!  So he went to yet another member who echoed exactly what I had read on line without me even opening my mouth! 

Further more he took the plane off after a fairly rigorous pre flight including checking where the CG was.  He walked out to the center of the field and took the plane off straight away from him.  What a beautiful takeoff.  The plane looked beautiful in the air and finally looked well mannered on the ground.  If you had only seen that take off you would never have suspected there was a problem.

Cubs and Citabrias tails will come up before their wings are ready to fly.  Leave them on the ground to build up speed and they become mild mannered.  Take them off as soon the tail leaves the ground and they will bite you.  Both planes need to have some right rudder factored into the take off procedure, and you'll find the rudder is much more effective when it comes up so you will need to reduce it some when that happens.

I took the Cub off the next flight for Dick and he flew and landed it with a huge smile on his face.  I just followed Barry's example and did not have a problem.  :)

If you screw up using too much rudder and the plane starts off the centerline just throttle down and bring it back around and start again.  Gentle take offs in my opinion are much easier to manage partly because things happen slower and to my mind the take off becomes a thing of beauty with the tail raising off the runway running on the mains and then taking off.  It just looks amazing.

If your model has problems taxing straight make sure both wheels are freely rotating.   I put a drop of 3 in 1 oil on the axle.  Also check that the tail wheel is centered, obviously if it is canted to the left or right that is the direction the model will track to.  A slow taxi will reveal if the three wheels track properly.

There has been an argument for years as to whether to use toe in or toe out to help a keep model tracking straight.  Most of the people I've read say to use about 2 - 3 degrees toe in on a tail dragger but I've read some who are just as adamant that toe out is proper.  I was reading on RCU the other day and Bruce Tharpe who was the designer of Sig's 4 Star, Mid Star, ¼ scale Space walker and his own companies designs of the Flying King and the Venture 60 etc. commented that he does neither!  He just makes sure that his models track as close as humanly possible straight ahead.