JC's Planes and Projects

Great Planes CAP 232

This was the sweetest building and flying experience that I have had so far in modeling! After building the Giles, I decided to cannibalize the radio and engine from the Kadet. The CAP built up quickly and is a fine looking and flying airplane. It is currently the best "tracking" aerobatic plane that I have but I am continuing to fine-tune it. I just recently went to an 11x5 APC prop and it improved vertical penetration while slowing the plane down. I initially had a problem with flutter with an APC 11x6 prop. I suspected the ailerons and have sealed the hinge gaps. When the wind is calm, I grab the CAP and head for the field - this is a fun little airplane!

Builder Notes: I had to shim a little more right-thrust than that built into the firewall for straighter up-lines. The plane will come out slightly tail heavy with OS .46 FX/Slimline muffler up front and a rudder servo mounted in the tail. Knowing this, I added weight to the nose by strengthening the forward fuse and landing gear blocks. I also put a few extra coats of paint on the cowl. I only needed about 1.5" of lead in the nose to balance. Seal your hinge gaps and make sure your linkages are tight! If your kit comes with soft aileron stock, call GP or buy some hard stuff for better torsional rigidity.

3/18/01 - Had a little mishap last weekend on take-off. The field was a little spongy and I did a high-speed nose-over. Cracked the fin/rudder off at the fuse junction. Repair was quick and simple. While I had the plane on the bench I decided to check all the incidence angles to see if anything was amiss. The plane had exhibited a positive pitching in power-off dives. This can be the result of wing/stab incidence angles or a forward CG. I really think that my CG is good - so I bought a Robart Incidence Meter and checked on alignment. The wing/stab were at 0-0 as indicated on the plans. However, my thrust-line was negative 1.5 degrees! The plans call for positive two degrees (which is a little unusual but confirmed by Great Planes). The firewall was OK, it was my poorly drilled holes for the engine mounting that resulted in the down-thrust. I used washers to shim the thrust-line to a positive 0.5 degrees. The plans call for more, but I will test this adjustment first.

3/25/01 - I made a few other modifications to the CAP while it was on the bench. I added four black Monokote shooting-star bars on the underside of the wing. The bottom of the wing had been completely yellow. This change was needed to get a better perspective on overhead maneuvers and when flying in low light conditions. I also sealed the aileron hinge gaps. I did this by cutting out strips of Monokote in 0.5" widths and folding them in half lengthwise. I then tucked the creased strip into the hinge line and ironed it on while holding the aileron fully deflected. This resulted in a very slick hinge gap seal with no possibility of limiting the deflection of the surface. To reduce the possibility of another nose-over, I made a 1/32" shim out of two pieces of 1/64" plywood. This is the only way to shim! You can cut this thin ply with scissors. I placed the shim between the aluminum gear and the fuse to move the gear forward.

3/23/01 - When I first started flying the CAP, I was unfamiliar with dual-rates so I set the rates to be "in the middle." This was fine then, but now I use dual rates to perform different aerobatic maneuvers. Also, the elevator setting of "in the middle" was on the hairy-edge of causing a high-speed stall at full deflection. The indication was perfectly executed hexagonal loops! Yep, it would enter the loop, start stalling, track straight, stop stalling and start along the loop curvature again, and repeat. I took the time to set up dual-rates per the instructions. GP says that the low-rate elevator will not cause a high-speed stall. The CG was rechecked and found to be just a tad behind the target, but well within the +/- 0.25" allowance.

3/25/01 - I installed an Ernst charging jack on the CAP. This is a great product and I highly recommend it. I can now check/charge my batteries at the field without taking the wing off. This is the third season for the RX nicads on this plane and I want to keep an eye on them. I found the Ernst product to install easily and be a very precisely molded product. It even has a little rubber boot to block the charge receptacle when not in use. Finally put my contact information and AMA number in the plane. This is part of the AMA safety code and should be on all aircraft! Waiting for good weather to test all the modifications.

3/31/01 - Eureka! The correction to the thrust-line worked out very well. After take-off, I needed down trim. After the plane was trimmed I rolled her upside down and required just a little push to maintain level inverted flight - much less than was previously required. The rolls are now much more axial. Another benefit was with the knife-edge mixing. I had needed 20% mix of rudder-to-elevator to get uncoupled knife-edge flight. After programming today I ended up with 5% for right rudder and 8% for left rudder! I optimize my mixes for level knife-edge flight and this requires less than full rudder deflection. At full rudder defection less than 10% mix was required. Roll coupling has always been negligible at less than 5% and I did not change that mix today. The results of taking the time to align all the incidence angles has paid-off. The plane is more enjoyable than ever to fly. The forward shimmed landing gear was also a welcome change with less tendency to nose-over and no adverse effect on high or low speed ground handling.