knight1

I was looking into changing the rubber bands to wing bolts on my TT60 trainer.
I'm trying to find the best way to mount them. I bought a couple of bolt kits from Tower.
These bands became a pain after awhile.
Maybe Minn could help with one his great illustrations
Thanks inadvanced

Here is the pic.

MinnFlyer

My Feedback: (4)

OK, lemme finish my coffee and I'll see what I can do

knight1

Thanks Minn, your da best.

riceh03

I too will be interested in this process. Sounds like something I might want to do also.

MinnFlyer

My Feedback: (4)

Ok, with that plane the conversion should be easy, because the windshield goes up over the front of the wing. But the first thing you must check, is that there is a PLYWOOD former in the fuse forward of the Leading Edge of the wing. If there is not, you will have to add one, and it must be deep enough into the fuse that it will lift the entire fuse (Including G-Forces). Next you will have to epoxy two plywood blocks (About 3/8" thick) to the fuse sides and the Fuse Former at the rear of the radio compartment (A). (Some square or tri balsa stock under these is a good idea too)

You will also want to remove a little covering from the center of the Trailing Edge and glue a piece of 1/8" plywood as wide as the Fuse to strengthen it for the bolts (So they won't pull through the wing during a loop!)

Now put the wing in place and rubberband it down so it won't move. And drill two 1/4" holes STRAIGHT through the windshield (and plywood fuse bulkhead)-into the LE- and through the wing joiner. Next, drill 2 holes through the trailing edge and block "A" (Your choice as to what size depending on if you want to use 1/4" nylon bolts, or steel bolts with blind nuts). If you're planning to use 1/4-20 Nylon bolts, drill these holes 13/64", then tap block "A" with 1/4-20 threads, and after the wing has been removed, re-drill the wing holes to 1/4".

You can then add two 1/4" dowels to the holes in the LE. Make sure they go all the way into the wing joiner. And if the wing insn't fiberglassed in the center section, It would be a good idea to do that (Lest the dowels pull through the LE)

vinnie

My Feedback: (1)

Mike, Knight1...
If I may add - make sure those annoying torque rods, if any, don't interfere with Blocks "A". Been there. []

knight1

Look's fairly simple.
Alot easier to comprehend with an illustration.
thanks Minn.
Now maybe I can get more flights out of it per day, instead of playing with elastics 1/4 of the time.

MinnFlyer

My Feedback: (4)

Very good point Vinnie. That's why 2 blocks are used instead of one long one across the whole fuse.

Scar

My Feedback: (3)

Wow... if you're spending a fourth of your time at the field working on rubber bands, there's something else wrong. Rubber bands are essentially string 'em & fling 'em. What on earth are you doing with them?

I've seen 3 planes converted to bolts from rubber band wing mounting - one Eagle II, and two AeroStars. All three had aileron torque rod interference after conversion, and had to be altered for that. Two of them, the wing popped off a few months later - in flight.

Thus, I recommend using a different plane, if you want a bolt-on-wing.

Just my 2¢ worth,
Dave Olson

knight1

Scar, I didn't really mean 1/4 of my time, It was a figure of speech.
and not everyone has the same luck as the plane U saw that broke from bolting.

I personally hate the elastics on my plane, rather bolt and go.
Mine didn't crash yet, but when it does it does, then I'll fix it.

heh, speaking of crashing, Minn do you have any crash awards?
I saw the Solo ones you had.

MinnFlyer

My Feedback: (4)

Yea, but when you crash, you can glue the pieces to your wall. No Certificate needed.

knight1

lol

a65l

My Feedback: (17)

Thanx for excellent picture. Am going to wing bolts on my Avistar eventually myself.

aimmaintenance

I'm doin a conversion on a plane of mine right now. I'll post a couple pics Friday night and tell ya how it went. (allthough I don't forsee any problems).

Just keep torque rod interference in mind and make sure ya don't drill a hole in your tank!

riceh03

Thanks Minnflyer for the good explanation. The pictures really help.

wrongwaywayne

I agree rubber bands are a pain, but those nylon bolts are not much better. My planes have made several attempts at going underground and so far not one nylon wing bolt has done what it is supposed to do - that is break! Instead the bolt mounting blocks get ripped out along with several pounds of fuse. The wing still gets damaged. They are sure not designed to break, if they were they would. A guy yesterday put a spitfire into the ground on take off (tip stall) and half the fuse ripped out but the bolts were still solid.

MinnFlyer

My Feedback: (4)

This is something that I have said all along.

Rubber bands are there for a reason.

You should only switch to bolts if you feel confident enough in your abilities to risk ripping you plane to pieces.

Bolts do NOT shear! (And if they do, there won't be much left of your airplane)

Example. a 1/4-20 Nylon bolt has a 432lb shear strength (According to: http://www.plasticnutsandbolts.com/m...ltestdata.html).

What do you think will happen if you lay your airplane on its side and set a 432lb weight on it?

stuk_at_work

My Feedback: (111)

Nice description Mike.

I am in the process of recovering a Midwest Aerostar and was toying with the idea of switching over to bolts. Not only do I not like the look of the rubber bands, but the bolts force consistent alignment each and every time you mount the wing, something difficult to do with just the bands.

FHHuber

MinnFlyer has a NICE explaination except he left out one point... you usually need to reinforce the LE in the area of the dowels. This is especially true of .60 size ARF trainers getting this conversion!

A .60 size kit that has the option of either bolt-on or rubber band... the Great Planes PT-60. If doing rubber band mount the structure is the same at the center LE of the wing as your ARF. If doing the bolt-on wing, you have a loead bearing block that is 3/4 inch front to rear that fills from loweer sheeting to upper sheeting at the leading edge. This block is full width from the root rib to the next rib... it gets epoxied in place. The kit supplies a 1/8 aircraft ply plate and medium balsa for making that load bearing block.

phread59

Minn has a good idea. And reinforcing the leading edge is a good idea. Glassing the center is also a good idea. I have an alternative idea. it will require some surgury and recovering. Do the plywood on the fuse and trailing edge just as Minn showed. You want to remove covering below the main spar and leading edge. Make a new dihedral brace out of 1/8 aircraft plywood the heigth of the LE and spar. The new brace will have a tab that extends down into the fuse about 1 1/2". You ideally will go out to the first rib bay. You Then remove ebough sheeting to epoxie the new braces to the back of the LE and the front of the spars. You may need to repair the sheeting and recover it. Rubber band the wing on and drill through the windshield just as Minn suggests. Add your 1/4" hardwood dowels. Be sure to go through both tabs. Add your rear blocks just as Minn showed and away you go. This is the set up I used on my Kadet SR. It is a very solid set up and will reinforce the wing center section at the same time. It may sound difficult but once you see it it is simple. The plans for the RCM advanced Trainer that was in RCM a coupla months ago show the same kind of setup. Look in the magazine and you will see what I am talking about. Simple idea, hard to explain. Maybe Minn can do one of his famous drawings here, Hows about it Minn?

Mark Shuman

MinnFlyer

My Feedback: (4)

I didn't forget...

Although I could have emphasized it more.

Anyway, I think this is what Phread was describing:

wrongwaywayne

Has anyone ever tried cutting part of the bolt away -- to make it weaker? This might be tempting fate.

phread59

Bingo! Thanks Minn,as per usual right on the money. i just do not have the ability or the inclination to be any where as good as you. I for one would like to stand up and applaud (here's where you take your bow, you earned it).

Mark Shuman

FHHuber

You are correct... cutting part of the bolt away i asking it to break. Instead... if the plane size weight and preformance doesn't require a 1/4-20 use 10-24... on down to 2-56. (yes they do make 2-56 nylon bolts.)

if you want to promote bolt snapping on wingtip mpact.. you have the bottom of the wing (high wing plane) met by a 1/32 ply plate, (drilled as if it were a washer for the bolt) over a balsa block which extends down to the hardwood or plywood which is threaded for the bolt. The thin ply acts as a knife if you have a wingtip impact. It won't bother the nylon bolt in normal flight.

wings

I see the theorey behind that wayne, but I personally wouldn't do it. Unless you can have the bolt machined perfectly with smooth radiuses on the cut down part, you will create stress points. This will cause the bolt to break prematurely while flying. I would almost go with smaller bolts if I went that route.

But if you think about it, if you hit the ground very hard you will damage the wing with both rubber bands or bolts. The benifit of the rubber bands is for breaking in softer crashes, but more times than not if you crash the plane you will have damage either way. The questions is, do you want to sacrifice a possible failure in the air for a small chance of saving a wing on a crash?

I know from experience that after a wing is broken in the air, your plane is history. A wing can be rebuilt, but when the entire plane looks like tooth picks you are done.

Wings