On  my previous post "How many Zeros does a person need?", the topic evolved into a discussion of line sliders, and an elevator correcting device called a "jump buster". The basic premise is this: On a slider equipped airplane, when the slider is in the low speed position, the elevator is no longer neutral because the bellcrank is rotated. Additionally, the throttle rigging is also altered due to the apparent shortening of the throttle line. The jump buster works by "re-routing" the rear elevation control line, thus effectively shortening it and retaining a neutral elevator position. It also reduces or eliminates the throttle rigging issues.

I had always been of the "that's just the way it is/ I need the up elevator anyway" school of thought, so I never gave the jump buster concept much thought. When I started flying the green Zero last year, I noticed that I was actually giving down control in low speed, indicating that the slider was cranking in more up than I needed. Being as open minded and receptive to new ideas as I am (hah!), this seemed like a good candidate to try out the jump buster.

All the installations I had seen on other peoples' airplanes involved line clips, cables, strings, and such, so I wanted  to do something cleaner and simpler. The pictures show what I came up with. A music wire "croquet wicket" is mounted into the wing. To find the correct location, I traced the position of the rear line in its high speed position on the wing (OK, I actually traced it onto masking tape stuck on the wing). Next, I hooked up the lines and handle, had a helper hold the handle neutral, and put the slider in the slow speed position. Then, I held the rear line against the wing on the line I had drawn, and moved along the line until I found the position where the elevator was neutral.
This is where I put the "wicket". Note that the wicket doesn't interfere with the lines in the high speed position, and is low profile enough that the other lines can slide over it without getting snagged.. The wicket only needs to be big enough for the line end to fit through. I made mine out of 1/16" music wire. The end that is inside the wing is bent to look something like a paperclip, just so that the epoxy could hold it in place better.

Back to back flights using and not using the jump buster confirm that it makes this particular plane fly better. I haven't tried it on anything else, but I will be installing one on my next Hellcat. I won't go so far as saying it is always better, but it is worth a try.

For more proof that I am not afraid of change, notice the engine on this airplane. I recently put together a Tune-Hill 36, and was looking for a test plane to put some time on the new Frank Bowman piston ring. I removed the reverse rotation Wiley 36, and installed the normal rotation Tune-Hill. I wasn't interested in the high speed (yet), but the engine ran so nicely that I will be leaving it on. The airplane was a bit tail heavy with the Wiley, so the heavier engine helped, and I DIDN'T MISS THE FACT THAT IT WASN'T REVERSE ROTATION! There, I said it. It ran so smoothly, and had such linear throttle response, it's going to stay. I'm pretty sure it will be slower than the Wiley, but I DON'T CARE. It's too pleasant and fun the way it is.

Gee, I hope this doesn't mean something is wrong with me...

Orin Humphries  from Washington is the the person that I would credit. He published the idea in the carrier newsletter over 20 years ago. Until recently, I had always dismissed it as unnecessary. Not so any longer. 

Orin Humphries  from Washington is the the person that I would credit. He published the idea in the carrier newsletter over 20 years ago. Until recently, I had always dismissed it as unnecessary. Not so any longer. 

Vaguely remember that.   Challenged him and the group to come to Lincoln NATS.   Him and the others are a great group of people.   Now Bill you have came up with another ingeneous idea to a problem.   Cut into the Brodak Gaurdian to do something similar.  The elevator change made it too hard to handle for me.  Now I just need to fly it.   No I have not gotten the K&B in a plane yet.   Give me another decade or so.