replica's other than p-51 p-40

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cluttonfred

Well-Known Member
Supporting Member
J.L., I don't understand what you mean at all. How are cables inside the struts going to fulfill the role of the bracing cables in a biplane?

J.L. Frusha

Well-Known Member
J.L., I don't understand what you mean at all. How are cables inside the struts going to fulfill the role of the bracing cables in a biplane?
Take a look at the EAA Biplane. Adding a few diagonal struts and stronger spars eliminates almost all of the cables, by redistributing the stresses, minimizing the cable drag.

Also note the change to the fuselage/wing struts that opens up the pilots view forward, where the Curtiss JN4 and S-1 have those inverted V struts restricting the pilots view.

With better design, I think all of the exposed cables can be eliminated.

cluttonfred

Well-Known Member
Supporting Member
J.L., I think you underestimate the complications that will come out of that sort of radical design change. Going from a two-bay (per side) wing with bracing wires and no center section to a single-bay wing with struts instead of wires is a complete redesign. Good luck, though.

J.L. Frusha

Well-Known Member
J.L., I think you underestimate the complications that will come out of that sort of radical design change. Going from a two-bay (per side) wing with bracing wires and no center section to a single-bay wing with struts instead of wires is a complete redesign. Good luck, though.
I'm already planning to scale it down, aiming for Part 103. It doesn't have to be a perfect scale reproduction for me, although the nostalgic look is a good thing. I'm not a stickler for absolute authenticity, either.

Saville

Well-Known Member
Take a look at the EAA Biplane. Adding a few diagonal struts and stronger spars eliminates almost all of the cables, by redistributing the stresses, minimizing the cable drag.

Also note the change to the fuselage/wing struts that opens up the pilots view forward, where the Curtiss JN4 and S-1 have those inverted V struts restricting the pilots view.

With better design, I think all of the exposed cables can be eliminated.

View attachment 121588

J.L. I think one of the problems you are going to have is if you choose to use the original Curtiss Stinson Special
wing section. It's extremely thin compared to the EAA Biplane you picture. The EAA biplane can have much thicker spars than the Stinson Special.

Though as you say, N struts do help eliminate some cabling.

pylon500

Well-Known Member
Supporting Member
I'd have a look around at how many non-externally braced 103 class aircraft there are out there, and maybe ask yourself why so few?
External wires and struts only start to make noticeable drag when you get to the top of the 103 speed range.
Cantilever wing structures need to be fairly thick to be light and strong, as soon as you start going thinner, the amount of material required to maintain strength rapidly starts to increase.
You can save weight by using stronger material, but then the costs start to go up, for example;
Many homebuilders using aluminium, build with 6061-T6. More professional builders will use 2024-T3, which is (not going to bother looking and guess) just over a third stronger, a little more expensive and a little harder to work.
If you really want to get serious, you can build with 7075-T6, which is nearly twice the strength of 6061, and about twice the price.
(I would have quoted 0.016" here, but the Spruce catalogue doesn't have 7075 in 16 thou'.
0.025" 6061-T6 sheet = $171.00 0.025" 2024-T3 sheet =$196.00
0.025" 7075-T6 sheet = $317.00 Or you could build in wood or carbon, both probably more expensive than alloy. But looking at your drawings, you may be interested in something like this; And with enough careful designing and building, you could almost squeeze it into Far103...? J.L. Frusha Well-Known Member J.L. I think one of the problems you are going to have is if you choose to use the original Curtiss Stinson Special wing section. It's extremely thin compared to the EAA Biplane you picture. The EAA biplane can have much thicker spars than the Stinson Special. Though as you say, N struts do help eliminate some cabling. Thinking more along the lines on modifying the wings off the Pamperito from South America (Brazil?). Descended from the Hovey Whing Ding II, but has foam ribs and ailerons, instead of using Aluminum tubing and wing warping. J.L. Frusha Well-Known Member I'd have a look around at how many non-externally braced 103 class aircraft there are out there, and maybe ask yourself why so few? External wires and struts only start to make noticeable drag when you get to the top of the 103 speed range. Cantilever wing structures need to be fairly thick to be light and strong, as soon as you start going thinner, the amount of material required to maintain strength rapidly starts to increase. You can save weight by using stronger material, but then the costs start to go up, for example; Many homebuilders using aluminium, build with 6061-T6. More professional builders will use 2024-T3, which is (not going to bother looking and guess) just over a third stronger, a little more expensive and a little harder to work. If you really want to get serious, you can build with 7075-T6, which is nearly twice the strength of 6061, and about twice the price. (I would have quoted 0.016" here, but the Spruce catalogue doesn't have 7075 in 16 thou'. 0.025" 6061-T6 sheet =$171.00
0.025" 2024-T3 sheet = $196.00 0.025" 7075-T6 sheet =$317.00
Or you could build in wood or carbon, both probably more expensive than alloy.

But looking at your drawings, you may be interested in something like this;
View attachment 121637
And with enough careful designing and building, you could almost squeeze it into Far103...?
Actually, I've wanted a Jenny for as long as I can remember, but, just a 1-hole job, not a 2-seater. Th Curtis Stinson fills the bill nicely.

Messing around with the Gee Bee was more about my wife, but it will have a lot of work with the drawings, before I begin considering the structure.

Riggerrob

Well-Known Member
I'd have a look around at how many non-externally braced 103 class aircraft there are out there, and maybe ask yourself why so few?
External wires and struts only start to make noticeable drag when you get to the top of the 103 speed range.
Cantilever wing structures need to be fairly thick to be light and strong, as soon as you start going thinner, the amount of material required to maintain strength rapidly starts to increase.
You can save weight by using stronger material, but then the costs start to go up, for example;
Many homebuilders using aluminium, build with 6061-T6. More professional builders will use 2024-T3, which is (not going to bother looking and guess) just over a third stronger, a little more expensive and a little harder to work.
If you really want to get serious, you can build with 7075-T6, which is nearly twice the strength of 6061, and about twice the price.
(I would have quoted 0.016" here, but the Spruce catalogue doesn't have 7075 in 16 thou'.
0.025" 6061-T6 sheet = $171.00 0.025" 2024-T3 sheet =$196.00
0.025" 7075-T6 sheet = \$317.00
Or you could build in wood or carbon, both probably more expensive than alloy.

But looking at your drawings, you may be interested in something like this;
View attachment 121637
And with enough careful designing and building, you could almost squeeze it into Far103...?

Note that most gull wings (e.g Hall Bulldog, PZL) also have bracing struts.
Part of the problem is the tiny root chord being too small to be rigid.

TFF

Well-Known Member
No struts knight twister. Essentially two cantilevered wings. Most still add them. Lift and landing struts, Andreasson Hawk, Acrolite, and Durand and plenty others. You can’t just get rid of wires without doing it some other way. Box kite as to have them somehow.

J.L. Frusha

Well-Known Member
So, anyone have any experience building the Early Bird Jenny?

I'm looking for plans and advice on the build.

Plans will be modified to make a scale Curtiss S-1 Speed Scout and to use 2 sets of the slightly shorter EBJ bottom wings, as well as the tail-feathers. It'll still be a 2-bay biplane, regardless. The original Curtiss-Simpson Special had those features.

Bill-Higdon

Well-Known Member
So, anyone have any experience building the Early Bird Jenny?

I'm looking for plans and advice on the build.

Plans will be modified to make a scale Curtiss S-1 Speed Scout and to use 2 sets of the slightly shorter EBJ bottom wings, as well as the tail-feathers. It'll still be a 2-bay biplane, regardless. The original Curtiss-Simpson Special had those features.
There was a slow group on yahoo till it got closed down, now only activity I've seen is on facebook

J.L. Frusha

Well-Known Member
There was a slow group on yahoo till it got closed down, now only activity I've seen is on facebook
Found it, joined and asked about plans.

pylon500

Well-Known Member
Supporting Member
So, before the thread got highjacked, we were talking about replicas, and out of the blue I clicked on this older youtube to find this;

And apart from the questionable front end, this seems like a good effort.
Can't find details of it's origin, but definitely a fair bit of work.

Torpedoes?

J.L. Frusha

Well-Known Member
Hijacked? Almost all of the American pilots of WWI learned to fly in Curtiss JNs. The replicas count as warplanes other than P-51s and P-40s. Many trained in San Antonio Texas at the Stinson flight school, or Kelly Airfield.

Bill-Higdon

Well-Known Member
How about a full scale Martin 162A which was a 1/4 scale PBM Mariner?

PTAirco

Well-Known Member

How about a half scale Stirling? Pobjoy Niagara engines.

Tiger Tim

Well-Known Member
How about a full scale Martin 162A which was a 1/4 scale PBM Mariner?
View attachment 128843
I only today learned that thing was apparently single-engined with belt(?) drive to the prop shafts. I always assumed it had a pair of Lamberts or Warners or something.