Campgems

Last fall, I picked up a big 120 size old pattern plane. I'm finally getting around to getting it ready to fly and I've come across a couple susprises so far. First was the engine. I have a O.S . 120 Surpass II that I intended to put in. The plane had a Tatone mount that on quick inspection looked like it was drilled for the 120. I found though that I had to cut some fuselage back to the firewall to allow the carb/regulator to clear, and then I had to mill a 1/4" piece out of the center of the motor mount to allow clearance. The motor bolted right in at that point. However, I'm going to have to add 3/4" of balsa and another spinner ring as the motor is to long for the orginal setup.

My real problem though is the aileron servos. The wing is 78" and the bird is going to weigh well over 10 lbs from the feel of it so far. It had set for several years and there is surface rust on the landing gear. I decided to pull the aileron servos out to see what they were and upgrade them if needed. The servo was sheeted over with just the shaft protrouding. Well When I cut the sheeting back to get at the servo, I found they were the old S148 Futabas. I need to replace them with something with some more athority. Here is where my problem lies. The guy, who ever he was, built the servo wiring into the wing. There is an extention on each servo, and a Y harness in the center. The servo lead was wrapped in masking tape and glued to the first rib at the servo end. I opened up the hole where the spliit harness exits the wing enough to get my finger in to feel around and the guy did the same wrap and glue there it looks like. In addition, the extentions were wrapped in masking tape. The one hole through the rib I found was a rectangle cut just big enough to push the servo end through. That all but eliminates any possibility of pulling the old wiring out and pulling new in. At this point, it looks as if I'm going to have to skin the wing and cut an opening in the sheeting near the center to get the old wiring out and new wiring in.

Prior to starting this, I though I would post my problem and see if there were some ideas on how to approach this that I hadn't though of.

PS, on top of this, I found that the used 120 had stripped glow plug threads and the head is no longer avaible. I sent it to Clarence Lee to have him work his magic on it. Hope that is all I run into with the engine.

Thanks for your ideas on this.

Don

qldviking

I have had similar issues in the past, what did was pull the wiring out and used a 1/2" piece of brass tube with a serated end to ream out the holes, that way you can easily run a ratline and pull your ectensions through. I have done this with both built up and fpoam core wings.
as for your motor, any decent mechanic or machine shop should be able to fit a helicoil or a bushing, not too expensive either.

Campgems

I can't get the tubing into the wing is my problem. The center section is sheeted for about a foot or more on each side of the fuselage. In addition, the old wiring is still in place and no way that I see now to get it out without cutting balsa. If I could get the wiring out, I would put in a home made extention, putting the ends on after the wiring is in place. HUMMMMM. a light bulb just turned on then went right off. If I could get the wires out of the plugs, then they should pull OK, but I can't get to the plugs.

Clarence Lee has the engine now and is replacing the threads. $20. My wife ask me why I didn't do it with all the equipment I have. I told her I needed a special tool that ran around $80 to do the job. "How often would you use it?" Never again unless I buy another used engine with the problem.

Thanks for the input though.

By the way, arn't you in the area of the big oil spill?? How is the cleanup coming on that one??

Don

Campgems

I forgot to point out that the wing is a one piece monster. Sure wish it was split, then the problem would be minor.

Don

qldviking

I see what you mean regarding the wiring hmmmmmmmm an interesting one indeed. I'll scratch my fleas some on that one.[sm=71_71.gif]
I am about 900 miles north of that spill, but from all reports it looks like the usual government snafu as far as the clean up goes.

is the centre section fibreglassed or just balsa sheeted?

Campgems

I decided to quit whining and get to work. I cut the covering on the bottom on two bays. That gave me the ability to get to the end of the extention and to undo enough of the masking tape that I was able to get the servos out. An interesting point is that with all the tape and glue, the servo to extention plug was just barely plugged and one even bent at the plug while I was pulling on it. The next step was to cut an 1 1/2" wide by to long on the first side, hatch on the top. I cut it very carefully and should be able to spot a coule tabs in and put the plugs back in when I'm finished. The second side will have just two hatches now that I know the rib patteren. I have the wiring striped on one side now. The second will go fast. I'm really tempted to pull the landing gear mounts out and put in retractw while I'm mucking around here. I should wait to see the this thing even flys though.

The wing on this is the heaviest wing I've ever seen. The construction could be greatly improved. It was real old school. 1/2" main spars. 3/32 hard bals ribs with no lightening holes. The rear spar is a big 3/8" wood dowl and there are also 1/8" x 1/2 cap spars over and under it. A big hunk of wood for the TE. I've probably removed 3 to 4 oz of masking tape from the wiring so far. It looks like everything was glued together with Ambroid. the sheeting is all 3/32" and the servo rails are 3/8" aircraft ply, set with enough tri stock to build a smal rubber powered model.

I'll fish a pull string through the ribs prior to closing it up and pull a cable through to install ends on later.

I think I'm going to put my idea of a 1" lead on the servo end so I just have one connection in the each wing half, right at the servo.

I was really sorry to hear about that spill. That is some nice beach area along there. I live along the coast here, and they keep wanting to put more off shore oil rigs in. The oil fields inland have a not so fine repretation for containing spills, and I can only imagine what would happen with the offshore wells.

Don

Sharpeye22

If you can unstick the wire at the center section spot you could just cut the y harness into two attach a string to each and pull it out from the servo end.
Then use the string to pull the new wire to the center.
sharpeye

qldviking

personally, I'd just use 2 channels for the ailerons, and run a single ext for each, and just ca the ends in the servo bays to keep them in place and make it easier to plug the servo lead in.

Campgems

The two channels is what got me into this to begin with. I saw the Y harness and decided it had to go straight away. If they had given me another inch and a half of leads, I may not have dug into the wings like I did. Once I found those little 40 size servos, well they just had to go. I'm looking at the elevator also. If things don't balance out well, I'll pull the single servo and split pushrod and put a couple servos aft, one on each channel.

My imediate goal is to get it flying and see how it goes. If it looks like a keeper, I think I'll put in Pull Pulll rudder, dual elevator servos and pull the nose wheel off and maybe some retracts and turn it into a tail dragger. Maybe even some air brakes for landing as I"m betting this thing comes in like a rocket.

To many projects and to little time.

Don

qldviking

thats one advantage with dual channel aileron set up, u can use them as flaperons too if needed. I did that with my last one, just 10-12 degrees down made a noticable difference to slow speed handling. As for the tail feathers, thi big ssue there is weight and balance, I start with puu-pull rudder and see where you end up. Pattern planes do not like extra weight, I'd probably look at c/f landing and taildragger set up myself