I am drawing plans for a tri motor bi plane
12-17-2014, 11:32 PM
#1
Thread Starter
I am drawing plans for a tri motor bi plane
This is a future build project I am designing guys. I have two birds to finish and the wife insist I build a ¼ scale Pitts first before this design, but she does want me to build it. She loves bi planes and round engines. How lucky is that? It will be a some time before any wood gets cut. We will be moving again soon. That is one reason for not much building at this time.
So here is the Design I am working since at the moment (and likely will last several more months) I am not in a place where I can do much building if any.
I am designing a tri motor bi plane. Sort of a ’28-’29ish passenger plane.
It started was going to be derived from a Kadet SR and sort of retain that look. But as the design has progressed that look has been lost.
So here are the numbers.
Top wing 78”
Bottom wing 72”
Bottom wing is also an inverted gull wing to keep the separation at 1 chord
Both chords 10”
Total wing area 1500sq”
Flat bottomed Kadet airfoil
Overall length 62”
Projected power plants three .30 4c
Triple tailed (3 vert fins)
Not The best drawings I know. I have DraftSight But haven’t bean able to make heads or tails of it. So I just drew these out on graph paper at 1/5 scale, scanned them as pdf’s and then copied pasted into paint. I had to reduce the size to be able to post them. I drew an earlier version last year that had 2 gull wings making it look like an X fighter or something. Just could not stomach the darn thing.
Haven't had time to do a top view yet
Ken
So here is the Design I am working since at the moment (and likely will last several more months) I am not in a place where I can do much building if any.
I am designing a tri motor bi plane. Sort of a ’28-’29ish passenger plane.
It started was going to be derived from a Kadet SR and sort of retain that look. But as the design has progressed that look has been lost.
So here are the numbers.
Top wing 78”
Bottom wing 72”
Bottom wing is also an inverted gull wing to keep the separation at 1 chord
Both chords 10”
Total wing area 1500sq”
Flat bottomed Kadet airfoil
Overall length 62”
Projected power plants three .30 4c
Triple tailed (3 vert fins)
Not The best drawings I know. I have DraftSight But haven’t bean able to make heads or tails of it. So I just drew these out on graph paper at 1/5 scale, scanned them as pdf’s and then copied pasted into paint. I had to reduce the size to be able to post them. I drew an earlier version last year that had 2 gull wings making it look like an X fighter or something. Just could not stomach the darn thing.
Haven't had time to do a top view yet
Ken
12-18-2014, 10:01 AM
#5
Thread Starter
The drawing of construction detail will wait till I do a clean full scale drawing. But I have been giving it a lot of thought. Stick fuse construction ala Kadet SR. Stick tail feathers.
Bolt on tail feathers and a course wings. Do to car size, and assembly issues 3 piece wings.
If I make the break point of the wings at the bottom of the gull, the the outer wing panels can remain attached to each other. And then the middle sections would bolt on to the fuse. But that also means the 2 inner section must be detached from each other. And then that also means at least 2 bolts of the engine pods also require being fussed with each time. Pain in the fanny.
If I added 2" or 3" to the bottom wing at the fuse juncture that were parallel with the top wing wing then the wing panels on each side could detach as 1 piece with the engine pods. Much easier, less bolts to fuss with with and yada yada yada.
I will have to draw that. Use square laminated joiner rods the are glued into each wing panel section and then pass through the fuse into the opposite wing panels.
Would that be structurally sound? if I went that rought, how much straight inner wing (bottom wing) would I need structurally?
Ken
Bolt on tail feathers and a course wings. Do to car size, and assembly issues 3 piece wings.
If I make the break point of the wings at the bottom of the gull, the the outer wing panels can remain attached to each other. And then the middle sections would bolt on to the fuse. But that also means the 2 inner section must be detached from each other. And then that also means at least 2 bolts of the engine pods also require being fussed with each time. Pain in the fanny.
If I added 2" or 3" to the bottom wing at the fuse juncture that were parallel with the top wing wing then the wing panels on each side could detach as 1 piece with the engine pods. Much easier, less bolts to fuss with with and yada yada yada.
I will have to draw that. Use square laminated joiner rods the are glued into each wing panel section and then pass through the fuse into the opposite wing panels.
Would that be structurally sound? if I went that rought, how much straight inner wing (bottom wing) would I need structurally?
Ken
12-18-2014, 10:10 AM
#6
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If nothing else I'd suggest on your version that you move the cockpit and canopy ahead a little.
And if you were to make the fuselage with a built up design similar to old timer spark free flight models the tail would come out light enough to allow shortening the nose to produce an even more 20's to 30's like look.
Mind you with 1500 square inches of area and 3 .30's it won't lack for a low wing loading....
12-18-2014, 10:24 AM
#7
Thread Starter
That was the inspiration smithcreek I have a small folder of pictures of that plane and several others as well. I think I was making the joiner drawing when you posted
The model 80 has a smaller chord wing the the top wing. I guess that is one way to move the wings closer to each other and not have to much drag induce there.
With same chord wings I had to find a way to keep the gap reasonable and not have a monster deep fuse, hence the inverted gull.
Ken
The model 80 has a smaller chord wing the the top wing. I guess that is one way to move the wings closer to each other and not have to much drag induce there.
With same chord wings I had to find a way to keep the gap reasonable and not have a monster deep fuse, hence the inverted gull.
Ken
12-18-2014, 10:55 AM
#8
My Feedback: (20)
Ken, I have a Handley-Page O-400 that is somewhat similar to your planned model. It is built with the fuselage and wings out to and including the nacelles as a single piece. The wing cells attach via hinges on the lower wing and straps on the top wings. I bolt up the hinges with the wing cell hanging down, then swing it up and bolt up the straps. Makes for about 5 minutes of assembly time. Structurally this works out nicely.
Chuck
Chuck
12-18-2014, 12:38 PM
#9
Thread Starter
That make sense Chuck. I think my second stab at it is closer to what you have. My first front view would pose field assembly issues. The last pic I posted has a short straight section that aesthetically I really don't care for but makes for easy field assembly because it is much closer to yours. I will work up a better drawing later. Gotta get back to painting the closet I am repairing.
Ken
Ken
