turbojoe

My Feedback: (8)

I'll start with what I did for leading edge dowels. Because of the relatively small l.e. on my LT-40 I had to go with 1/4" dowels. Two dowels didn't look strong enough so here is what I did: 1/8" light ply doublers on both sides of the center of #1 ribs. Carefully drilled dead center between them. Dowel fits great. Now a total of three dowels. I put 1/2" square hardwood block immediately behind the l.e. and another at the wing joiner for rear support. Dowels are 4" long from end to end. My only concern it the dowel diameter. Are the three 1/4"dowels going to be strong enough? If so then lets continue to the next question:
How deep should the mounting bolt blocks be mounted? Should they be flush with the bottom of the wing? Or a little deeper to be able to put a little "tension" on the wing. For other reasons there will be light ply on the underside of the wing in the bolt area that would allow the wing to contact the blocks without damage to the wing. I also intend to space the blocks out from the rear bulkhead so the bolts go through a much thicker section of the trailing edge. I do NOT want the wing to come off in flight! Any suggestions would be welcome if I'm doing something wrong.

Ed Smith

Once something fails I never use it again. If the airplane lasts any length of time the wing dowels sticking out of the leading edge will wear and get sloppy.

I use four screws to hold my wings on, no dowels. My wing blocks go right through the wing. The screw is in the solid block for its whole length. The screw actualy screws the wing block against the block in the saddle. There is no centresection "Give" with this set up. Need I say that the wing block is securely fastened to the wing?

Ed S

Mighty Mouse-RCU

My Feedback: (145)

Unless you are going to put a OS FX90 on that LT40, I am sure teh 1/4 inch dowls will be fine. But as Ed says they tend to wear, taking them on and off and vibration. You can either coat with ca to harden them or coat with epoxy. After the glue sets up they should be harder and not wear as much. The trailing wing bolts can really be done any way you wish, but have no fear, the wing wont come off using the recomended engine.

turbojoe

My Feedback: (8)

How about if I don't glue the dowels in? Make them replaceable. The "windshield" will keep them from moving forward. There is no chance of leading edge wear as the dowels are completely supported by hardwood not by the l.e. Look at the picture and I think you'll agree it won't fall apart anytime soon. I still haven't finished glueing either. It's more or less tacked together at this point.

Mighty Mouse-RCU

My Feedback: (145)

I would glue them in personally, I know the dowls are being slid into the hardwood blocks, but its the dowels that will wear at the point where they slide in to the holes in the fuse. Sometimes even the holes themselves wear. But this wear is after many many flights. Ususally the plane wont last that long. Many of my planes only have one dowl holding the wing to the fuse. I think you may be overly cautious. Your wing will not fall off. I've never seen a wing break at the dowls. Often times you beef up what you think the weak area is and then another area becomes the weakest link. Also if you beef up a bunch at the wing attachement, it will not break at that point but at another which may be more difficult to repair. What engine are you going to put on it? How long have you been flying and what is your flying style? Some folks I know only have two speeds wide open and out of fuel.

majortom-RCU

My Feedback: (40)

For a long time the standard practice was one 1/4" dowel, then somebody decided two would be better, so now two 1/4" is the new standard. I never heard of any dowel failing, single or double. Now we have triple, and I think I can safely say something else will fail before the triple dowel fails.

My planes, like the Mighty Mouse's, usually don't last long enough for friction wear to be a problem.

But I must say I am tempted to try Ed's four screws approach. I have seen a couple examples of this, and like the way it works. I have a rubber banded Sr Kadet I got at auction, and I think I will fit four screws to it.

Mighty Mouse-RCU

My Feedback: (145)

It just sort of slows you down when you get to the field. I really anxious to get in the air when I unload. Lazy but, there ought to be a faster way to secure the wing. Like 4 clevis pins or something like that.

Someone11-RCU

My Feedback: (2)

Why don't you just use rubber bands instead of a bolt on - dowel wing? This is the Sig LT-40 trainer right.....? Are there any advantages when using a dowel and bolt on method?

Thanks

-Brian

turbojoe

My Feedback: (8)

The initial reason for going bolt on was because I couldn't find any #67 rubber bands locally. Gotta order from Sig.
#2 reason is I can't leave anything alone. I have to modify just about everything. I'm sure the rubber band vs bolt on method could be debated at length but it was mainly a matter of personal preference. Nothing more.

Someone11-RCU

My Feedback: (2)

I went to sigmfg.com and found the rubber bands, but I couldn't find #67. (I also have the LT-40... but the arf ) Do you think it would be okay to just use #64????? I already have a bunch of #64 rubber bands, thats why. I appreciate any input

THANKS!

-Brian

turbojoe

My Feedback: (8)

My understanding is that the #64's will stretch enough to go on but that they really crush the wing sheeting. This was one of the first things I read about the plane. I planned to do a bolt on from the very beginning. There are probably hundreds of these planes out there doing just fine with rubber bands. As I said I just can't leave anything alone. If something is working for you stick with it.

murphy

My Feedback: (19)

Bad,
I may only be in this her hobby for about 5 years, but from my own personal experience ( I was one of those guys that used to think "stronger is better") with re-inforcing stuff, I find it's sometimes better to "create a weaker link.

By this I mean things like I used to replace the scrawny little 6=32 nylon hold down botls with 1/4-20 steel ones on the wings, and the same for landing gear,,,,,, until it was time for my plane to do a cartwheel on landing, and have the wing bolts littlerally shred my fuse to pieces,,,, or the time a severely bouncy landing didn't simply shear off my mains, but did the "fuse shred" all over again, but this time from the bottom!!!!

I now use 1/4-20 nylon bolts on my gear, and if the model permits, rubberbands on my wings, and on at least 2 occasions, I firmly believe that this change of atitude has resulted in my simply needing to repair a broken off nylon bolt instead of an entire fuse!!!

Only my opinion,,, take it for what it's worth,,,,,

turbojoe

My Feedback: (8)

Murphy you're right. I do have the "stronger is better" and can't leave well enough alone mentality. Been that way all my life. Just gotta tinker ya know. ( I seriously thought about trying to fit retracts on this thing somehow too!)
I have a few options here as I haven't glued the dowels in. I could go with one on either outside edge for a total of two or just one center dowel. The wing bolts are standard 1/4-20 nylon. I basically did what this guy did only I made it a bit stronger:
http://www.concentric.net/~margen1/BushPlane.htm

flatfour

My Feedback: (8)

I didn't want to go thru the trouble of ordering #67's. My solution was #84 bands from an office supply chain store. They are the same length as 64 but twice as wide. Have had no problems with crushing the sheeting. Just have to give them a couple stretches first before putting them on.