1/2A stunt trainer design

If you get into the laser cutting biz, you might get really busy. I'd send you work for cutting ribs, I hate cutting ribs. Depending on the price, I'd be in for a beginner ringmaster bipe too.

rogermharris wrote:once i draw any plan up, it's just a matter of cutting the pieces. it would just be a matter of figuring out the cost of material. i can not wait to build one now!  the only thing i remember about this plane was the wings "cupped" the wrong way. not sure if cupped is the right word but basically ended up with inverted polar air foils so over time it looks like this but, it was a heck of a trainer!  maybee a brace to stop that from happening...

This is caused by how the dope is applied. Dope shrinks, and pulls wood to the hollow side. On plank surfaces it has to be applied to both sides at the same time before drying is allowed to happen. This way the wood stays straight. The effect can be used deliberately as a means to curve a surface too.

With enamel paint there is much less shrinkage so much less effect. With rattle can application both sides can be painted quickly enough that they are still wet at the same time.

Phil

good to know phil!
it was so long ago that i don't recall if it was that way when first built or over time got worse

rogermharris wrote:good to know phil!
it was so long ago that i don't recall if it was that way when first built or over time got worse

I expect it got worse over time. That type of thing always does.

Phil

While the dope is a factor to that problem, wood choice and dope selection is as well. Using the correct type of grade can eliminate cupping caused by dope. Many times the model is painted usually top side first and then the underside and left to dry on it's gear. The top side of the model flashes off while the underside is still wet. Applying more dope to the one side opposing the cup can sometimes reverse that in minutes. One thing to remember is that thinned dope is going to strengthen your wood far more than enamel will not to mention there's little to no weight penalty in using it. Using the proper dope is also important as there's 2 types taughtening and non taughtening. Sig Lite Coat is a plasticized dope which shrinks very little and won't cause issues on planked surfaces as pictured. It's used on free flight stick and tissue models. It also provides the highest resistance of fuel out of any of the dopes on the market today. Ken

Ken Cook wrote:While the dope is a factor to that problem, wood choice  and dope selection is as well. Using the correct type of grade can eliminate cupping caused by dope. Many times the model is painted usually top side first and then the underside and left to dry on it's gear. The top side of the model flashes off while the underside is still wet. Applying more dope to the one side opposing the cup can sometimes reverse that in minutes. One thing to remember is that thinned dope is going to strengthen your wood far more than enamel will not to mention there's little to no weight penalty in using it. Using the proper dope is also important as there's 2 types taughtening and non taughtening. Sig Lite Coat is a plasticized dope which shrinks very little and won't cause issues on planked surfaces as pictured. It's used on free flight stick and tissue models. It also provides the highest resistance of fuel out of any of the dopes on the market today. Ken

thanks for all the info ken!

i guess i need to order some lite coat dope
should i use a mid grade balsa for the wings?

Using C grain balsa is going to result in improving your chances in lessening warps. Sig Lite Coat is also the ticket. 8 oz. jar of Sig  Lite Coat equates to painting a lot of 1/2A models. While Sig Lite Coat can be used for tissue applications, it will not shrink the tissue to the degree that Sig Supercoat will if you decide on using it for this application. You must use Supercoat first or more followed by the Lite Coat to prevent further shrinkage. It's thick as syrup in the jar and it needs to be reduced with at least 60% thinner prior to use. I highly recommend using no other thinner than Sig. It's expensive but well worth the $$$. You will need twice the amount of thinner as the dope. You will find that when brushing outside from a open container you will need to replenish the thinner as it's evaporating from the jar during application. Don't use retarder with this dope even though Sig makes it.  Sig thinner is a slow drying dope. It does improve overall finish due to this as the brush strokes melt away. Ken

Interesting comments here regarding flaps. This is the way I hooked up mine: Is there a better way?



with a link to the throttle on this Enya 15:



Throttle advances full on up, flaps go down, elevator goes up. Makes for interesting flying as I recall. But it hasn't seen air time for years. Seen here before. I scratch built it using a horizontal stab from a crashed R/C model.

i was going to run the push rod from the bellcrank to the control horn on the flaps and then select a different home in the flap control horn and run another push rod back to the rudder. yours looks fine as well. i built a similar model back in the day with a carbureted engine and ran it with a third line. was specially fun for take offs and landings, touch and goes ect.

duke.johnson wrote:If you get into the laser cutting biz, you might get really busy.  I'd send you work for cutting ribs, I hate cutting ribs. Depending on the price, I'd be in for a beginner ringmaster bipe too.

If you need something cut, let me know. I have full use of our laser cutter whenever it's free.

rsv1cox wrote:Throttle advances full on up, flaps go down, elevator goes up.  Makes for interesting flying as I recall.  But it hasn't seen air time for years.  Seen here before.  I scratch built it using a horizontal stab from a crashed R/C model.

Surely as throttle goes on the flaps would go UP. More speed - less flap needed. Less speed (landing approach) - more flap needed.

ok... looks like $18 plus shipping for a Ringmaster Beginner Bipe kit.  this is for the balsa and plywood parts. wings and fuse will be cut from C grain Balsa.
i will order the material when i sell three

looks like this...

if you want the hardware, i will look into that as well.

Heck what a deal. I'll take one. Let me know when you have three ordered.

You KNOW I want one too !! I have some thing else I am wanting too when I get time I will get with you , right now my Damn water pump is out and heading down to basement to see whats up with it

Come on guys! Just one one more! These look like great little kits and the ringmaster flyathon will be here before we know it.

rogermharris wrote:

duke.johnson wrote:If you get into the laser cutting biz, you might get really busy.  I'd send you work for cutting ribs, I hate cutting ribs. Depending on the price, I'd be in for a beginner ringmaster bipe too.

If you need something cut, let me know. I have full use of our laser cutter whenever it's free.

Roger
I have some ribs I wouldn't mind having cut. How do we input them into the laser cutter? Do I just send you the template and you figure it out? I don't know.
Duke

Ok, I'm in. I love Bipes and that looks like a nice one and a simple build.

Bob

duke.johnson wrote:

Roger
I have some ribs I wouldn't mind having cut. How do we input them into the laser cutter? Do I just send you the template and you figure it out? I don't know.
Duke

duke,

you can send me pretty much any format and i can work from it. depending on the file format i may need some dimensional info. also if you can give me an idea of how much material i need and the thickness, i will add it to the order for the bipes

getback wrote:You KNOW I want one too !! I have some thing else I am wanting too when I get time I will get with you , right now my Damn water pump is out and heading down to basement to see whats up with it  

sorry to hear that! but, know the feeling... i had to replace my water heater a couple weeks ago. narrow steps and a dirt floor basement... really beat me up along with being muddy. not sure how long it had been leaking.

looks like we have three takers.. it's not going to weigh much so lets say $5 s&h

you can paypal me to my email address

i will also cut some 1" wheels to throw in.
if anyone else is interested i would be more than happy to add to the order

Roger
I'm not sure what I need for ribs yet. How soon do you need to know. I'm trying to get ready for a trip this weekend.
Duke

duke.johnson wrote:Roger
I'm not sure what I need for ribs yet. How soon do you need to know.  I'm trying to get ready for a trip this weekend.
Duke

what's the thickness you need?   1/16" ?
i will make sure i have the material on hand

rogermharris wrote:

duke.johnson wrote:Roger
I'm not sure what I need for ribs yet. How soon do you need to know.  I'm trying to get ready for a trip this weekend.
Duke

what's the thickness you need?   1/16" ?
i will make sure i have the material on hand

I see if I can dig out some planes tonight and check.