How to Wing Bolt Conversion??
 

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.

RE: How to Wing Bolt Conversion??
 

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

RE: How to Wing Bolt Conversion??
 

Thanks Minn, your da best.

RE: How to Wing Bolt Conversion??
 

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

RE: How to Wing Bolt Conversion??
 

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)

RE: How to Wing Bolt Conversion??
 

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

RE: How to Wing Bolt Conversion??
 

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.

RE: How to Wing Bolt Conversion??
 

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

RE: How to Wing Bolt Conversion??
 

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

RE: How to Wing Bolt Conversion??
 

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.

RE: How to Wing Bolt Conversion??
 

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

RE: How to Wing Bolt Conversion??
 

lol:)

RE: How to Wing Bolt Conversion??
 

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

RE: How to Wing Bolt Conversion??
 

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!

RE: How to Wing Bolt Conversion??
 

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

RE: How to Wing Bolt Conversion??
 

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.

RE: How to Wing Bolt Conversion??
 

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?

RE: How to Wing Bolt Conversion??
 

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.

RE: How to Wing Bolt Conversion??
 

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.

RE: How to Wing Bolt Conversion??
 

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

RE: How to Wing Bolt Conversion??
 

I didn't forget...

Although I could have emphasized it more.

Anyway, I think this is what Phread was describing:

RE: How to Wing Bolt Conversion??
 

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

RE: How to Wing Bolt Conversion??
 

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

RE: How to Wing Bolt Conversion??
 

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.

RE: How to Wing Bolt Conversion??
 

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

RE: How to Wing Bolt Conversion??
 

Thats a nice point, Wings.
That was also my theory.

I dont fall in love with my planes, I respect them. So if I lose one every now and then, so be it.
Its a hobby and I'm enjoying it ever so much.:D

RE: How to Wing Bolt Conversion??
 

Ouch that Kadet really took a beating. I never thought about the flying issues. Have you ever had a bolt loosen itself in flight?

RE: How to Wing Bolt Conversion??
 

No, that crash didn't result from the wing coming off, it resulted from the wing breaking when pulling out of a dive. I learned the hard way to cut the throttle immediately in a dive.

But, it would be the same result. After the wing seperated from the plane, it was like a high speed dart heading towards the ground. That was a sick feeling, because as I stood there and watched it coming down, there was not a thing I could do about it :(.


After impact, it took forever for the wing to every so gently spin to the ground like a feather. Half of the wing is still in a tree. Luckily the half that had the servos left made it back to earth.

Wings

RE: How to Wing Bolt Conversion??
 

Say Minnflyer, what are the breaking strenghts of the smaller bolts? I agree - you don't want failure in flight. Most inflight wing failures happen with positive G's and isnt that when the wing is pushing into the fuse (for a low wing plane. Sounds like the needs are different for low and high wings????

RE: How to Wing Bolt Conversion??
 

many years ago, when radios, airplanes, and pilots started getting better, some people decided to do away with their rubber bands and switch to bolts.

The idea of using nylon bolts was originally so that they would break on impact.

The idea didn't work.

Today, most people still use Nylon bolts simply because they won't vibrate loose like a steel screw/blind nut can.

I can't recall EVER seeing a crash where wing bolts failed in flight.

Here's a Strength chart:

RE: How to Wing Bolt Conversion??
 

Say Minnflyer - what size of wing bolts do you use??

RE: RE: How to Wing Bolt Conversion??
 

I usually use 1/4 -20, although on my Sig Wonder it has 10-24, but that's a very small plane.

RE: How to Wing Bolt Conversion??
 

The trainer that I just got done repeatedly killing went through Nylon wing bolts like candy. I had to order a 100 Ct. bag of them from the Airplane factory because when I first started flying it I would sometimes cart-wheel on either takeoff or landing. Also in every single crash the nylon bolt would shear, especially in ones where the wingtip impacted first. Bear in mind that the wing was mounted to the square alluminum fuse by two tandem bolts, one metal 1/4" right behind the wing spar and one nylon 1/4" right before the trailing edge. They do shear on my trainer, but I dont think that they will on my cub, which has four bolt/dowel insert points.

RE: How to Wing Bolt Conversion??
 

I was at a club meeting some told me there was a conversion kit for a hobbistar 60 mkIII to bolt the wing on vers. rubber bands
any ideas out there on if this is true and where could I get one

RE: How to Wing Bolt Conversion??
 

http://www.masportaviator.com/ah.asp?ID=106&Index=2

RE: How to Wing Bolt Conversion??
 

Newbie here looking for advice on a bolt-on wing. I am starting with an ARF - and Midwest Aerobat to be specific (uses dual aeleron servos). The wing halves have not been joined together yet. Like the guy with the TT60 trainer, the "windshield" of the fuse comes up over the leading edge of the wing. I was originally thinking of trying to attach the front of the wing with two dowels as outlined above but then came up with a different strategy that I will elaborate on shortly. Tonight, I decided to search for bolt-on wings which is how I finally arrived here; and found this thread quite interesting... and seems to be the perfect place to bounce this idea around.

My current idea involves adding two new center wing ribs, I photocopied the inside edge of one wing half so I would be able to make a template. With this template, I was going to add a 3/8"x3/8" tab to the front of the this rib. I was going to make two new ribs, using 1/8" thick plywood, and then epoxy them together. I was then going to epoxy a hard-wood block or two 1/8" plywood blocks on the front side of the plane's fuse former in front of the wing's leading edge. I then planned to drill a hole in the middle of this former and blocking material that will "accept" the 3/8"x3/8"x1/4" tab that is on the front of the two new ribs that will be glued between the wing halves. I will use a triangle-shaped file to create the corners in the hole that I drilled into the former/blocking material. I figured I could either glue a 1/4" strip of plywood onto the end of each side of the dihedral brace, or cut a new dihedral brace that is 1/4" longer on each end.

I have been pondering this now for several weeks and keep asking myself if I should attempt this or go with the rubber band-mounted system the plane came with.... At the field, I have seen several planes with bolt-on wings, but they generally seem to be low-wing planes that don't have the wing area of a typical trainer (thicker and smaller). That said, I wonder with this plane being a high-wing sport trainer, if I am asking for trouble by converting to a bolt-on wing, especially when pulling loops or pulling out of high-speed dives. I don't have the experience to know if the rubberbamds help dissipate (or spread out) some of these forces better then a bolted-on wing, etc. There seems to be varying opinions in this thread. I would be interested to hear what the thoughts (if any) are on using a single, but stronger, leading edge attachment scheme as I am thinking?

Here is a picture of the rib template I am considering....
Thanks in advance,
Loren

RE: How to Wing Bolt Conversion??
 

wether the wing bolts on or bands on doesn't make much difference in flight, if it's done correctly. It's your job, as the builder, to spread the loads the bolts will impose over enough of the wing and fuse to keep things strong. THat usually means installing a bolt plate in the wing, thu which the bolts go, that is strongly bonded to the wing structure. Likewise, the block that the bolt threads into must be strongly mounted to the fuse, in a manner in which it will not concentrate stress too much. Usually the wing saddle area is doubled anyway, providing good strength. I have both high wing and low wing planes I've convereted for bolt on wings.

In my mustang, I used a 3 bolt system, 2 bolts forward, 1 aft. I installed a spruce block in the front bottom of the wing, inset into the centre rib, and extending to the next rib in each direction, where it is again inset and glued full lenght to the landing gear block in the wing. In the rear, I installed a similar block, again securely braced to available ribs (actually this is in the 'stang's radiator bulge). In the plane, I installed maple blocks that span the fuse. Securely notched and epoxied to the fuse doublers of the wing saddle. Threaded the maple blocks to take 1/4-28 nylon bolts, hardened with CA.

In my high wing Aquastar 1/2a seaplane, I set 2 dowels in the LE, with matching holes drilled in the fuse former over top of the windshield. In the rear, I installed a maple block, as in the mustang, and a plywood plate recessed into the top of the wing's TE. A pair of nylon bolts join it all up. 1 would have been enough, but for some reason I used 2 bolts.

J

RE: How to Wing Bolt Conversion??
 

The front of a wing has most of the force against it, the rear of the wing - very little. A single 10-32 nylon flathead bolt is plenty strong enough, but I usually use two. The nice thing is that you can embed a piece of 1/8" plywood (aircraft grade, not light ply) and the 10-24 will countersink flat with the surface of the 1/8" ply.