PT40 wing advice
 

Is it possible to follow all the steps for both "rubber band" and "bolt on" wing configurations while building?

I'd like to do both and use the rubber bands to start and change to bolt configuration later.

Or, are the plans set up for one or the other.

PT40 wing advice
 

I don't really remember if the plans allow you to convert to bolts at a later time, but I'd suggest going with the bolt on method from the start. Rubber bands are a pain and they mess up the covering after a while.

One other piece of advise, build the "sport" wing with less dihedral. I built one last summer for my dad and I built the "trainer" wing and there is too much dihedral IMO. A 10mph crosswind will blow it right over.

Ben

PT40 wing advice
 

WhiteKnuckles - The idea that rubber bands will prevent damage in a crash is not true for the most part. If the wing gets twisted the fuselage will be damaged regardless of attachment method.

The real reason to use rubber bands is because many beginning builders have problems drilling the holes for wing bolts accurately. It's hard to go wrong with dowels and rubber bands.

But like bdphil said, they're messy, a continual expense and mess up the covering. Additionally the rubber band mounting method weighs more than using nylon bolts, but the difference is probably only a few grams.

My vote is that if you think you can successfully drill and tap for the bolts then go with that method.

A couple of tips:

1) Before you do anything get the wing on straight and level. Make a couple reference marks on the wing and fuselage.

2) Measure the exact center of the blocks in the fuselage for the bolts. Transfer those marks to the wing. Actually, you want to be centered back and forth, but slightly to the rear of center because of the way the bolts enter the blocks.

3) Drill the wing (3/16" bit for 1/4" bolts) with the drill perpendicular to where the bolt head will contact the wing. That means the bolt will go into the block at an angle.

4) Seek experienced help to step you through it in person before you attempt it on your own.

PT40 wing advice
 

Thanks guys. This site is incredible. I'm pretty confident of my ability to drill a hole, though I will seek advice first. :) I have been told, without variance, to definitely build the sport wing. I will follow that advice. I like the idea of a trainer, but I live in a very windy city and don't want to limit its lifespan prematurely. Cheers.

PT40 wing advice
 

Drilling the hole is easy. Getting it in the right place at the correct angle takes some preparation.

Glad you like it here. :thumbup:

PT40 wing advice
 

I'm sorry, but I TOTALLY disagree! Rubber bands will prevent a LOT of damage in case of a minor mishap. In the case of a major crash, they won't help any, but if a wingtip is jarred, all of that leverage is transferred to the tie-down point. If it is rubber, it will give. If it is bolts, something else has to give, and guess what it's going to be... You will split your fuselage open like a ripe mellon!

Please, use the rubber bands. You can graduate to bolts on your second or (better yet) your third plane.

PT40 wing advice
 

Thanks for your advice. It wouldn't be advice if we all thought the same way; it would be common sense. I'm leaning toward the "bolt on" method because I'm pretty much there in terms of the build. I've also got an advantage over some people in the sense that my club is good and I've got lots of people willing to instruct me. I should be able to take it slowly. I'm also thinking of throwing together a "trainer" SPAD and beating it to death. My balsa trainer is something I'd like to have for many years. We'll see. :)

PT40 wing advice
 

build the sport wing and use even less dihedril(sp) if your building skills are up to it. use rubber bands as stated in the previous post but go ahead and install the provisions for the bolts now and they can be drilled later. be sure to check the wing incedence (it's not perfict out of the box). I've built 2 PT 40s this year!! one for my son and one for me. rubber bands saved his fuselage in the tall grass. I split my fuselage in a simular situation using bolts.

PT40 wing advice
 

By "even less dyhedral" do you mean less than the sport wing plans in the manual? I would like a plane that I can fly for a longer period of time and still enjoy, as opposed to one that has a limited lifespan. If that means it's more difficult to learn, so be it. There are guys here who will train me on their PT40s that have tons of dyhedral. As for bands vs. bolts, perhaps I'll go and insert the parts and drill the holes for bands so I can do both. Thanks again to all of you.

PT40 wing advice
 

And what do you mean by "wing incidence"? I've had a few "incidents" already, none involving the wing. ;)

PT40 wing advice
 

Yes less than the sport wing, but not totally flat. It means you have to build new wing joiners or modify the current ones. be sure you carefuly measure your wing root cuts. the washout jigs would need to be shortened a little also.

PT40 wing advice
 

That's great advice. Thanks. My biggest fear was creating a wing that will either bore me to death or be unacceptable here in Calgary where the winds are very high.

PT40 wing advice
 

I'm glad you are building the Sport wing. The other one flys so crummy it is unreal. I spent 6 hours last summer chopping a students wing in half to fix it.

PT40 wing advice
 

Bearmech, how many inches of dyhedral do you recommend on each side?

PT40 wing advice
 

Go with rubber bands. They won't help in all mishaps, but it can really help in some accidents. There might be a way to crash that would cause more damage with rubber bands than bolts, but I'm having a hard time thinking up how. Building so you can switch to bolts later makes sense, though.

Also, a note on rubber bands, I think a lot of guys put way too many on the plane, taking a "more is better" approach, and being overly worried about losing the wing in flight. However, putting on too many bands leads to too much pressure on the wing, and reduces the ability of the bands to flex and absorb energy in an accident. For a .40 size trainer, with limited expected acrobatics (just enough acrobatics to avoid the ground when necessary), I'd say no more than 5 or 6 per side.

as a side note, my combat planes use rubber banded wings. I use 4 per side on my 3.5lb .28 powerd B class ships, plus an extra band run accross from font to front and another from rear to rear. The plane is a bit lighter than a trainer, but the G forces in the air are much higher. I've had many head-on wing-to-wing mid-airs, and let me tell you, having the wing move a little can really save your bacon, the energy absorbed can make the difference between landing in 1 peice or several. I've flown out of several mid-airs with the wing visible crooked, but the airplane still very flyable and controlable.

If you are worried about the wing shifting too much, you can borrow another combat trick, put velcro on the wing saddle and wing instead of the foam tape. The velcro gives a little bit, absorbing some energy, but will help keep the wing from coming all the way off.

PT40 wing advice
 

I think when I fixed my students we ended up using 1 3/4" total.

PT40 wing advice
 

I use 1.5" in the second pt40. seemed to work fine.

How about both?
 

I'm currently learning to fly on a kit built PT-40, and chose to build the wing with more dihedral.

My plans for when I outgrow that wing setup, is to scratch build a wing with less dihedral, such as the "sport" setup suggests.

Just another option to consider. Cheaper than building a complete new plane, but still fairly involved.

Good luck!

PT40 wing advice
 

If you go with bolts, use nylon bolts and make sure to use the propper drill before you try to tap it. I have seen many people use a 1/4 inch drill and then the tap just drops right through. Look at the tap and it will tell you which numbered drill to use. Buy that bit. it will make a better hole.

PT40 wing advice
 

TX, another, cheaper option would be to build a SPAD wing. Maybe build the SPAD wing with the extra dihedral, and the kit wing done flatter. That way, the SPAD wing takes the early abuse and you can save the "pretty" kit wing for later, when you're less likely to break it. (not that SPAD wings can't look nice, they sure can).

SPAD wing
 

A SPAD wing. I hadn't thought of that. Not only can I sleep easier, but I imagine it would be a faster build time. Which would you recommend, the Spadet maybe?

RE: PT40 wing advice
 

Did you ever switch over to bolts? If so, how much prep for the bolt sutup did you do during initial building and how much of a struggle was it to switch over? I'm building a PT-40 right now and wondered about doing the same.

RE: PT40 wing advice
 

Hey MTNLVR, I have the older version of this kit. Bolts were not an option when I built this kit. I do not know how the dowels go in. If they are to go in a bracket that drops below the wing (like the updated version of the RCM advanced trainer that I am building now.) . I would put the brackets in and drill the dowel holes and not install the leading edge dowels. if they are in the wing itself I would build the wing and install the dowels and drill the holes for the bolts. When flying with bands I would say you have to live with the dowels being used. Either way you would install the dowels for the rubber bands. I converted a Kadet SR to bolts. I used the band dowels anyway as reinforcements. Cut them off flush and covered the plane. I hope this helps.

Mark Shuman

RE: PT40 wing advice
 

phread59....Thanks for the idea. There is a plate that the single L.E. wing dowel goes into. The manual says to only install that plate if opting for the bolt-on wing so I'm not quite sure if it will cause and problem using rubber bands. I'm thinking of drilling the wing and preparing all the other stuff for the bolt-on, but then applying the covering over the dowel hole and the bolt holes in the wing. That way it looks nice and when I want to use bolts I'll just have to trim the holes and glue in a dowel.

I guess I'll see tonite what I decide to do.

RE: PT40 wing advice
 

If I read your post right the dowells go through the leading edge. If this is so I would definatly install the dowels. The reason being without the dowels you have a hole in the leading edge. This will create a stress point and a corresponding weak point. Just put the dowels in. Yea even though you are using bands the dowels will be engaged. Don't worry about this they will not be holding much. And will make centering the wing easier. The wing will go on straight and consistantly every time. Something that is hard to do with bands. Good luck and I hope you do well. Oh and don't worry about looks. Tey won't look bad. And if someone syas they look goofy who cares! Rule number 1,It's my D**N airplane! LOL

Mark Shuman