Snap rolls in a Super Decathlon

[Flying Lizard]

Any Super Decathlon pilots out there??

I spoke with an American Champion factory pilot, he said the plane is happy to snap all day long, just fly with maximum of 1/2 tanks and enter the roll at a steady 90 mph. But I've heard other folks say the plane shouldn't be snapped, for fear of some unspecified problem.

My bird is a 1999 and it did require a fuel tank replacement at about 500 hours; gas sloshing into a baffle caused it to leak. The factory said the new tank is a better design and shouldn't fail that way again. I suppose any roll is going to send the gas smashing into those baffles and the quicker the roll rate, the bigger the impact. Does anybody know of any other specific concerns with snaps?

Another question I have is about snap roll technique. When I snap it, the nose yaws all over the place during the roll. I've tried them with the stick back the whole time, with a little forward stick, with a little aileron into the roll, and with a little forward stick and aileron into the roll. Moving the stick does accelerate the rate, but there's still a sloppy lot of yawing going on and it feels out of control. I'm wondering if the rudder should be let out for some of the roll ...does anybody know of a way to snap this plane and avoid a lot of yawing?

Thanks!!!

 

[docmirror]

There were concerns about the empenage tubes coming apart. I had a Deke years ago that I would snap. We did find a broken tube along the bottom of the fuselage once, so I guess it's a valid concern. Also, the older ones had wood spar, I don't think that is an issue with yours.

As for technique, I guess I just haul back and right at the same time I stab the rudder. I let a little elevator go forward over the top, but not much. It's a yaw maneuver, so no way to get rid of it all.

 

[flyingcheesehead]

Calling Chip...

Speaking of which, where has Chip been?

 

[PittsDriver]

I don't know a single experience aerobatic pilot/competitor that will snap their Super D. At least one or two of those have that opinion from first hand damage they've experienced. If you're interested in talking to one experienced Super D aerobatic instructor, PM me and I'll give you his details.

 

[john smith]

(Working from memory, I have the SPORT AEROBATIC magazine articles somewhere)
In the mid/late 1980's we began to see a epidemic of seat back breakages in Decathlons and Citabrias.
At that time, snap rolls were included in the Intermediate sequences.
The right seatback upright tube would break at or above the hinge point. This was caused by pilots forcing the right side of the seatback rearward as they forcefully pressed left rudder and simultaneously aggressively pulled right and aft stick. This was further complicated by excessively high entry speeds.
The early solution was to apply a gusset to reinforce the upright tube. After a couple of years, upright tube failures began to appear at other points on the tube above the gusset.
At that point, snap rolls were dropped from the Intermediate sequences.
In the 90's, we began seeing longeron failures in Pitts Special aircraft. Again, the culprit was snap rolls entered at excessively high airspeed. If you follow Erich Mueller's recommendation and practice your maneuvers at the minimum possible airspeed, you will learn more about how to properly manipulate the controls to best perform the maneuver and not overstress your aircraft.

 

[AcroBoy]

I had about 400 hours in a Super Decathlon before moving on, and they are easy to snap. However, smoothness is more important than jerking the controls around, and they will not snap as fast as a Pitts or a monoplane. Also, need to keep the speed down to avoid overloading the plane. Even with the metal spar, it is important to look in the wing frequently to look for broken ribs, etc. The seat back and lift strut attach fitting failures should have been addressed by AD. I think most of the problems arise when pilots try to fly a Decathlon like an Extra or a Pitts- they require different inputs and skills.