PITTS s2s single wing conversion(monoplane)

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BOURNE

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Hello guys,

i have this pitts s2s im working on. Currently considering converting it to a mid wing airplane.
has it been done before, any suggestions?

cheers
bourne
 

BOURNE

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Any particular reason why?
other than having to redesign the wings. And wing placement
 

Dana

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I guess the question is why would you want to take one of the greatest airplanes ever designed and morph it into... something not so great.

But seriously, the entire aircraft is designed as a whole. The fuselage structure is optimized for mounting the wings in a biplane configuration. Change to a monoplane, and you might as well design an entirely new plane from scratch (which is what you'll be doing anyway, essentially).
 

BOURNE

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Thank You Dana.

it’s nice to meet people that adore the airplane.
stock S-2s loading.. image.jpg
 

BOURNE

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Already tack welded the fuselage. TiG welding is next. I have 1/8 filler rods er49-1, has anyone ever used this here?
 

BOURNE

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image.jpg
found Out that that’s it’s a variation of the er-70s.
the er70s-7.
 

Toobuilder

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My initial thought is "don't do it", but that goes against my long standing and oft repeated mantra of "define your requirements"...

That said, what are your requirements, and where is the S2S deficient? Put another way, what do you hope to improve with said modification?
 

TFF

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Buy some DR107 plans; maybe some Laser ones too. Did you build it as a single seater?

As a guess, Overall the tubing will probably be savable but all the center area seat forward would need to be gutted for the wing mounting as it will not be even close.
 

BOURNE

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My initial thought is "don't do it", but that goes against my long standing and oft repeated mantra of "define your requirements"...

That said, what are your requirements, and where is the S2S deficient? Put another way, what do you hope to improve with said modification?
fuel capacity and aircraft range. tapered wing with wing fuel tanks, and higher speed envelope
 

BOURNE

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Buy some DR107 plans; maybe some Laser ones too. Did you build it as a single seater?

As a guess, Overall the tubing will probably be savable but all the center area seat forward would need to be gutted for the wing mounting as it will not be even close.
Yes TFF,

built it as a single seater. noticed what you said concerning the wing mount. If I decided to go forward with it, would have to redesign the seat-forward structure.

cheers
Bourne
 

BOURNE

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Buy some DR107 plans; maybe some Laser ones too. Did you build it as a single seater?

As a guess, Overall the tubing will probably be savable but all the center area seat forward would need to be gutted for the wing mounting as it will not be even close.
The DR107 is exactly what the finished product could look like
 

Toobuilder

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fuel capacity and aircraft range. tapered wing with wing fuel tanks, and higher speed envelope
Ok, faster and further than a stock Pitts. That's getting closer, but what specific numbers do you need (speed, range, payload)? And why is a tapered wing a "requirement"? If an ellipse or hershey bar wing planform meets performance, is the taper still relevant?
 

TFF

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The designer of the DR107 designed a lot of modified Pitts planes before he did the One Design. There is a lot of DNA of Pitts in it. The Lazer 200 has some origins from the Cassutt racer, but most of these planes are of the same idea. The Kraft Super Fli was essentially a low wing Pitts. You also may look into planes like the Stits Playboy, Spezio Tuholer, and the Spacewalker. No need to do anything else until you know the direction you will go. It is much easier to pick one and follow the plans, than it is to pick and match what you like. It’s a lot of work and there is no need to waist a lot of time backtracking to the way it should have been.
 

Wanttaja

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Several questions:

First, do you intend to make a cantilever wing (e.g., totally internally braced) or use external bracing?

If you're going for cantilever, that's a massive change in the wing design. Here's a comparison between a Fly Baby wing (external bracing) and a Spacewalker (cantilever). The airplanes are otherwise very similar.
fly baby vs space walker spar dimensions.jpg
The Fly Baby has a plank spar 3/4" wide, and the Spacewalker has a built-up spar about three times that size. I'm unfamiliar with the Pitts wing, but it looks like it laminates two 3/4" pieces together. In any case, going with an appropriately-sized cantilever spar would be wider than the fuselage was designed to accommodate.

Plus the fact that the fuselage is design to carry the flight loads at the lower wing roots and the cabane struts, with the cross-bracing of the flying and landing wires handling much of the loads. You've eliminated that, with the cantilever wing. Plus you're putting the wing in a mid-position, FAR from the points that were originally designed to handle the loads. You'll have to significantly beef it up.

The other option would be to go with external bracing, either with cables or with struts. The problem with either is the shallow attachment angle to the fuselage. This significantly cuts down the efficiency of the bracing.

For example, here's a notional look at a mid-winged Fly Baby.
morane.jpg
The bulkheads the Fly Baby wings attach to are parallel and of similar construction all the way around, so the loads issue isn't as important. Note the bracing wires from the wheel hubs to the wings...very steep angle, so they're efficient. If these attached to the bottom of the fuselage, as you intend, they'd be at a very shallow angle. The load they'd have to withstand is much higher, ditto the places on the fuselage they attach to. The same problem exists for strut bracing; it eliminates the kingpost in the drawing, but you're still stuck with the very shallow angle.

Finally, too, consider the mechanism required to connect the aileron pushrods or cables to the control stick. Again, not sure how the Pitts works, but I bet the pushrods or cables went into the lower wing. How are you going to transmit the control stick motion to the mid-wing position? I'm sure it's solvable, but better start considering it now... it may affect the changes you'll need on the fuselage.

Ron Wanttaja
 

BOURNE

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Ok, faster and further than a stock Pitts. That's getting closer, but what specific numbers do you need (speed, range, payload)? And why is a tapered wing a "requirement"? If an ellipse or hershey bar wing planform meets performance, is the taper still relevant?
Cruise speed : 260 mph-280 mph
range: 750 - 800 miles
payload: 50lbs

the taper is just for maneuverability. I believe it’s more efficient. Considering some data and Red Bull airplanes
 

BOURNE

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Th
The designer of the DR107 designed a lot of modified Pitts planes before he did the One Design. There is a lot of DNA of Pitts in it. The Lazer 200 has some origins from the Cassutt racer, but most of these planes are of the same idea. The Kraft Super Fli was essentially a low wing Pitts. You also may look into planes like the Stits Playboy, Spezio Tuholer, and the Spacewalker. No need to do anything else until you know the direction you will go. It is much easier to pick one and follow the plans, than it is to pick and match what you like. It’s a lot of work and there is no need to waist a lot of time backtracking to the way it should have been.
thanks for you all.
i ll stick to the s2-s build and complete it- with some modifications of course.
The next build will be of my own design

cheers
Bourne
 

BOURNE

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C
Several questions:

First, do you intend to make a cantilever wing (e.g., totally internally braced) or use external bracing?

If you're going for cantilever, that's a massive change in the wing design. Here's a comparison between a Fly Baby wing (external bracing) and a Spacewalker (cantilever). The airplanes are otherwise very similar.
View attachment 110845
The Fly Baby has a plank spar 3/4" wide, and the Spacewalker has a built-up spar about three times that size. I'm unfamiliar with the Pitts wing, but it looks like it laminates two 3/4" pieces together. In any case, going with an appropriately-sized cantilever spar would be wider than the fuselage was designed to accommodate.

Plus the fact that the fuselage is design to carry the flight loads at the lower wing roots and the cabane struts, with the cross-bracing of the flying and landing wires handling much of the loads. You've eliminated that, with the cantilever wing. Plus you're putting the wing in a mid-position, FAR from the points that were originally designed to handle the loads. You'll have to significantly beef it up.

The other option would be to go with external bracing, either with cables or with struts. The problem with either is the shallow attachment angle to the fuselage. This significantly cuts down the efficiency of the bracing.

For example, here's a notional look at a mid-winged Fly Baby.
View attachment 110846
The bulkheads the Fly Baby wings attach to are parallel and of similar construction all the way around, so the loads issue isn't as important. Note the bracing wires from the wheel hubs to the wings...very steep angle, so they're efficient. If these attached to the bottom of the fuselage, as you intend, they'd be at a very shallow angle. The load they'd have to withstand is much higher, ditto the places on the fuselage they attach to. The same problem exists for strut bracing; it eliminates the kingpost in the drawing, but you're still stuck with the very shallow angle.

Finally, too, consider the mechanism required to connect the aileron pushrods or cables to the control stick. Again, not sure how the Pitts works, but I bet the pushrods or cables went into the lower wing. How are you going to transmit the control stick motion to the mid-wing position? I'm sure it's solvable, but better start considering it now... it may affect the changes you'll need on the fuselage.

Ron Wanttaja
wouldve used control cables and pulleys.
thanks for the info Ron.
 
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