Willy Nillie's Barnstormer Biplane

[rockyboy]

I'll get ya'll some more details on those clamps. The magic seems to be the hole the carbon fiber rod goes through is just snug enough that they slide when there is no sideways pressure on the clamp arm. Making bigger ones with an arrow shaft sized rod should be no problem. I think I've got some little carbon rod scraps somewhere around the shop and might play with making some wooden ones too

 

[Wildthing]

I'll get ya'll some more details on those clamps. The magic seems to be the hole the carbon fiber rod goes through is just snug enough that they slide when there is no sideways pressure on the clamp arm. Making bigger ones with an arrow shaft sized rod should be no problem. I think I've got some little carbon rod scraps somewhere around the shop and might play with making some wooden ones too

So just the friction as you try to spread the clamps apart at the jaw end holds it inplace?

 

[TooJung2Die]

You'll have no problem drilling the right size hole if you have proper drill index. It doesn’t have to be CF rod. Hardwood dowel will work fine.

 

[rockyboy]

So just the friction as you try to spread the clamps apart at the jaw end holds it inplace?

Yep - that's it. The materials of the arm and the rod need to not be so smooth and hard that they would prevent "binding up" when angular force at the end of the clamping arm tries to twist the arm.

You have no problem drilling the right size hole if you have proper drill index. It doesn’t have to be CF rod. Hardwood dowel will work fine.

I think a hardwood dowel might actually work better for larger sized clamps. Needs experimentation!

 

[Turbojoe]

Back to the bipe conversion. What do you plan to do as far as incidence between the two wings? Positive, zero or negative and on which wing? Over the years I've read so many discussions on the subject with no clear cut best method. The confusion has kept me from adding a second wing to several of my planes that would be so much cooler as a bipe. I have had a few bipes over the years but never drug out the incidence meter to see where each of them were incidence wise. That was one of those "shoulda done's". I'm watching the thread with great interest. Maybe the prototype cabanes from Doug will be a great add on option purchase bundled with a second wing. That would make these kits approach the versatility of the Mountain Models EVA kits.

Joe

 

[rockyboy]

Yeah, that's one of those "Microsoft vs Apple vs Linux" arguments

I have seen a lot of people preferring a negative decolage (angle of the wings in relation to each other) on biplanes, but they seem to be more symmetrical airfoil and pattern type ships, and many of the flat bottom airfoil designs & articles go with a positive decolage.

https://www.modelairplanenews.com/p...-up-your-plane-to-fly-right/#visitor_pref_pop

I'm initially going for a positive stagger (top wing forward of the bottom wing) and have the bottom wing and horizontal stabilizer be at 0 degrees and the top wing around 1 degrees positive (so a positive decolage - angle of wings in relation to each other). This is what I've got on the Dreamer and All Star, and I like it so far.

What will work best? Don't know yet - need to get her in the air and see!

 

[Turbojoe]

Sounds like what you're doing is like my Mountain Models EVA Bipes. That plane flys great with the forward biased swept upper wing. Absolutely MUST keep a tick or two of power on when landing her. The drag of that extra wing can complicate landings if you get her too slow. Keep just a bit of power on and landings are a thing of beauty though. Try to glide in at zero throttle and it gets really ugly in a hurry....

I really should check incidence on one of of my EVA'S. It may be time to do my own biplane.......

Joe

 

[Willy Nillies]

Hi Guys,

You are all right on track. A very good rule to follow for sport type biplanes both model and full scale is: MOST FORWARD wing positive 1.5 to 3 degrees relative to the most rearward wing. Horizontal incidence will depend on airfoil selection, but generally 0 to +1.5 degrees to most rearward wing if using a symmetrical airfoil and +1 to +2.5 degrees positive (upward force on tail to keep nose down) for sem-symmetrical and clark y or other high lift airfoil. Engine down thrust should be treated like any other airplane.

The reason the most forward wing should be positive to the rearward wing is for stall recovery. When the most forward wing is more positive than the rear wing, it will stall first while the rearward wing will still be flying.... acts like a canard.

If only using ailerons on 1 wing, make sure to put them on the MOST REARWARD wing. That way you will maintain the most aileron authority through a stall.

Hope this helps.

Rockyboy: The plywood cabanes were shipped. Consider them a starting point. Modify as you see fit.

Sincerely,
Doug (and Becky)
WillyNillies.com

 

[rockyboy]

Sounds like what you're doing is like my Mountain Models EVA Bipes. That plane flys great with the forward biased swept upper wing. Absolutely MUST keep a tick or two of power on when landing her. The drag of that extra wing can complicate landings if you get her too slow. Keep just a bit of power on and landings are a thing of beauty though. Try to glide in at zero throttle and it gets really ugly in a hurry....

I really should check incidence on one of of my EVA'S. It may be time to do my own biplane.......

Joe

I'll have to remember the landing advice - I have a reoccuring problem with cutting throttle out too early when landing!

And yes - it's always time to make more biplanes!

Hi Guys,

You are all right on track. A very good rule to follow for sport type biplanes both model and full scale is: MOST FORWARD wing positive 1.5 to 3 degrees relative to the most rearward wing. Horizontal incidence will depend on airfoil selection, but generally 0 to +1.5 degrees to most rearward wing if using a symmetrical airfoil and +1 to +2.5 degrees positive (upward force on tail to keep nose down) for sem-symmetrical and clark y or other high lift airfoil. Engine down thrust should be treated like any other airplane.

The reason the most forward wing should be positive to the rearward wing is for stall recovery. When the most forward wing is more positive than the rear wing, it will stall first while the rearward wing will still be flying.... acts like a canard.

If only using ailerons on 1 wing, make sure to put them on the MOST REARWARD wing. That way you will maintain the most aileron authority through a stall.

Hope this helps.

Rockyboy: The plywood cabanes were shipped. Consider them a starting point. Modify as you see fit.

Sincerely,
Doug (and Becky)
WillyNillies.com

Thanks Doug! That's a more aggressive wing incidence than I've seen on the couple of bipes I've built so far, but I always had a hard time believing that only 1 degree really had that much impact at RC scale anyway!

And thank you very much for the cabanes! Looking forward to getting the fuse mocked up and ready for assembly with these!

 

[Duffusmonkey]

Holey cow! That's a lot of holes! It makes me want to buy two kits and make it a biplane. It just has that old time "we HAVE to make this as light as possible" look.

Keep it up!

 

[rockyboy]

Holey cow! That's a lot of holes! It makes me want to buy two kits and make it a biplane. It just has that old time "we HAVE to make this as light as possible" look.

Keep it up!

Yes! Come on in - the water's fine!

 

[rockyboy]

Here's a couple close ups of the clamps for everyone who wants to build some.


I also got a minute before heading to the volleyball game to glue the last fuselage former in place and the rear sheeting part one.

 

[rockyboy]

Look what arrived in the mail today!

Couldn't resist just clamping them in place temporarily

Going to cut them a little shorter than this I think - will need to put the ailerons in place on the bottom wing and do some measuring to see how much.

Getting excited here - can see her coming together now!

 

[Willy Nillies]

Looks great! I intentionally made the uprights extra long so that you could trim down to desired length.

Sincerely,
Doug and Becky
WIllyNillies.com

 

[TooJung2Die]

That's looking much better as a bipe than a monoplane. That's alotta holes.

 

[Turbojoe]

It kinda sorta reminds me of a Tiger Moth.

Joe

 

[rockyboy]

Building away...

So I clamped the cabanes on out outside temporarily and adjusted things so the wing spacing is the same as the chord width.

Proportions look pretty good here...

Nothing is glued down here so of course it's tilted all over - but you can see the wingspan difference between the top and bottom.

TLAR for cutting the front leg of the cabane off since the battery tray is already installed...

And with a little nudging, a level, and an incidence meter things are looking pretty decent.

So I'm going with the top wing at 2 degrees - you can see the orange level keeping the datum line across the top of the fuselage and horizontal stabilizer at 0. The semi-symmetrical wing on the bottom just naturally wants to sit at -1 degree which gives a total spread of 3 between the wings.

Doing a negative on the bottom wing isn't very common - but it's also not unheard of. The whole system could also be looked at as the bottom being being at 0 degrees with a +3 on the top wing and a +1 on the horizontal stab, which is a setup I've seen discussed on a forum talking about F3 pattern biplane designs. Course in that example the wings were the same width, so not all variables are equal by a long shot.

I'm thinking I'll do the bottom wing as a bolt in, while keeping the top rubber banded for ease of construction.

Anyone have ideas for what WW1 plane this setup most resembles? Are we still in Tiger Moth land Joe?

 

[The Hangar]

I gotta get me one of these Willy Nillies kits! They look awesome! Problem is money doesn’t grow on trees and I don’t have too much patience. It would be good for me though! I love how they look and I’ve really wanted to do a balsa kit...

 

[rockyboy]

I gotta get me one of these Willy Nillies kits! They look awesome! Problem is money doesn’t grow on trees and I don’t have too much patience. It would be good for me though! I love how they look and I’ve really wanted to do a balsa kit...

Money is always a factor in any RC decision, but I've got to say these are the best deal on new balsa kits you will find anywhere (IMHO). These laser cut designs build great - I'd recommend them even for a first time balsa builder. And so far I've only seen and experienced good things about their flight capabilities too as long as you're not a beginning flyer. And at this little park flyer size, all the electronics are reasonably priced too!

 

[The Hangar]

Money is always a factor in any RC decision, but I've got to say these are the best deal on new balsa kits you will find anywhere (IMHO). These laser cut designs build great - I'd recommend them even for a first time balsa builder. And so far I've only seen and experienced good things about their flight capabilities too as long as you're not planning And at this little park flyer size, all the electronics are reasonably priced too!

Yeah, they seem like a really good deal. I really like what you did to your stick with the green monoKote so I’ll try to replicate it.