Sport Pilot Talk

Cub flyer · Joined: 10 Sep 2006 Posts: 593

I rode in a two place Challenger this morning. back seat.

503 Rotax and two aboard. full fuel. Performance was fine. Airplane climbed well and would cruise up into the yellow arc if allowed. 2 cycle 503 ran well and was smooth. Why it has electric start but lever chokes on the carbs is beyond me. You can't reach the choke from the cockpit.

Some observations I had.

Hard to climb into the back seat. Practice may help.
Your feet are very high on each side of the pilot. Kind of like being in those tables the doctors have with stirrups.

There is no other place to put your feet with structure and fabric floor in the airplane. What do you do when not flying? legs are wedged between the doors and front seater. How's that work with doors off?

Doors have bungee latches which are near impossible to secure under your legs on each side of the pilot

Stability was lousy. Sunny day with little wind, some thermals but not that bad.

Pitch required constant attention due to what felt like flex in the airframe and control system, Flaperons for trim was bad in the Kitfox and same in the challenger

Rudder had no centering and yaw stability was non existent. The airplane could move from maximum slip angle on either side with no feedback on the pedals. Sometimes it took a lot of pressure to get it back and then no pressure it would keep swinging on through neutral to the other side. I had my own skid ball in the back seat to watch things.

Ailerons had a huge amount of adverse yaw. Heavy forces and the stick was short with a lot of cable stretch or flexing somewhere. The airplane seemed reluctant to respond at times, I could not see anything flexing on the airframe.

my question is do they all fly this way? We're going to install the sub fins on the stabilizer tips tomorrow and try flying with no doors.

How do they fly these with floats? I hear people rave about how good they are. This one appears stock and well built. Has 250 hours or so Total time. I've flown other airplanes with yaw and pitch problems including early Kitfox I, II, III and the X air but this Challenger was beyond both.

I'm not even sure I want to fly in it again. I told the owners I'd give them a ride in the PA-11 tomorrow. If all the Challengers fly this way I can't imagine how they can sell them to anyone or how in the world they are going to learn how to fly it.

Might be this particular airframe but I don't know. It has the 503 with belt drive and tennessee prop, back country gear, BRS on top, with fairing, doors and airfoiled wing strut fairings. Vertical fin appears stock with gaps taped up and dorsal fin extending up to just behind the prop. no rudder tab installed but there are brackets. Wings are pop riveted to the ribs and covered with Stits or ceconite fabric.

Any changes we can make to help it fly better?

FLA-CFI · Joined: 27 Oct 2008 Posts: 45

I've flown one....503 powered, stock, no doors, BRS equipped.

It flew much better than you described. In fact it is probably the 3rd most fun plane I've flown....behind a J3 cub and T-28 trojan.
Not knowing a whole lot about the airframe, I would suggest flying a few others as this one sounds like it is out of rig or something is off.
And sit in the front seat as well, totally different experience.

Cub flyer · Joined: 10 Sep 2006 Posts: 593

We're working on it now. Turns out the previous owner had the rudder trim tab and auxiliary fins. They are not the plastic finlets but instead 1/8" ply plates for each side of the horizontal. Close enough.

Installed the plates and yaw was better with two people. But it needed enough right rudder to make your leg shake.

Back down and installed the rudder fixed tab. Also removed by the previous owner.

Now yaw is barely neutral flying solo. Pitch is also barely neutral bordering on divergent. Going to move battery forward and try it.

How the owner flew it an hour to deliver amazes me.

Pitch and yaw better with two on board.

Also the adjustable heel stirrups on the rudder pedals were all the way up. Moving them down for better feel and we'll try again.

Then try without doors.

Cub flyer · Joined: 10 Sep 2006 Posts: 593

Talking to the owners the airplane is a 1995 version.

Flew again this afternoon with doors off. No real change other than the CG change with two aboard made it more stable. We lowered the heel plates on the rudder pedals and I left my shoes on the ground. Better.

A little turbulence that was minor in the PA-11 was a big deal in the Challenger. Every bump had a different effect on the airframe.

What I did not like was turning base to final it took a lot of pressure on the ailerons to start the turn. I pushed and pushed and nothing was happening. Felt like I was bending the stick. I used rudder to skid on purpose to keep from missing the runway. After the turn started then it came around suddenly and ailerons were working again. Just not a good feeling. One of our CFI's was on the ground and said the tail looked bent when I flew over. If it takes full leg pressure on the rudder I can see how. The rudder trim tab just masks the load on the tail. The airplane feels like it's fighting itself. There is a lot of torsional flex in the fuselage if you wiggle the tail on the ground. The rudder deflection alone would twist the tail.

After that I took off in a Aeronca Chief and had engine failure at about 50 ft AGL. throttled back and it started running again at low power. Over the power lines and turned to line up with the field furrows. Added power and it quit again after a few seconds with no field remaining. throttled back to idle again and glided a few seconds. Added enough power to just hold altitude and make it around a tight pattern and land. Different problems and airplane. We've tried everything and I think it may be some kind of intermittent fuel feed problem. I teach all students with a power loss throttle back and find the RPM which will keep it running and hopefully it is enough to get to a good spot to land. Most engine failures are in fact fuel delivery problems and while it won't run at takeoff power it will run at some other setting. Keep that in mind.

I walked over and hugged the Cub fuselage and took off to test out the new Icom radio. Very nice intercom function and good range. The Cub is so easy to fly compared to the Challenger I can't imagine learning in anything else. The challenger required constant undivided attention to fly through every bump. I think the airframe is flexing in turbulence and that is why it pitches or yaws off heading with every bump. Same day I could roll the Cub into a 30 degree bank and add a little up trim. It stays coordinated and flies around in circles hands off ignoring the turbulence.

We did a couple wing overs and lazy 8's for fun.

Talking with the Challenger owners we agreed to fly the Challenger in calm weather and the PA-11 if there is any wind. Then they'll get a tailwheel sign off.

Hope the new Challengers fly better. There are a lot of changes so I think they have it figured out. I'd have to fly one to see.