Sopwith Baby Project

[Joe Perkel]

Regarding this part, (top aileron balance lever).

The plans call for the lower bracket with the bolt holes to be 22 G.M.S.P, and the top streamlined lever section to be 18 G.M.S.T.

Easy enough to figure out the 22 / 18 Gage Mild Steel, but what is the significance of the P. and T?

Thanks!

[Leatherhead]

P=plate
T=tube

I looked at the Pup drawings. It's almost the same. The "u"-shaped plate and triangular lever arm are both 22 guage, mild steel plate. The upper tube is 18 guage, mild steel. The lower tube is 18 guage, brass.

[Joe Perkel]

Originally Posted by Leatherhead

P=plate
T=tube

I looked at the Pup drawings. It's almost the same. The "u"-shaped plate and triangular lever arm are both 22 guage, mild steel plate. The upper tube is 18 guage, mild steel. The lower tube is 18 guage, brass.

Leatherhead,

I suspected "P" was plate but, what confused me about "T" in this case was the two halves of an airfoil section welded together.

I'm Having trouble figuring out how to shape (for manufacture) either tube or sheet to this section, which varies along the long axis. Then the radius at the top.

Suspect maybe this kind of thing may be a good candidate for this outfit..Online Machine Shop - Instant Pricing

convinced Pup, Baby, and Strutter are all variations of the same basic design.

Thanks a lot Leatherhead!

[Leatherhead]

Joe,

I'm pretty sure the "lever" section is not tube. Does your drawing indicate this? If so, it's probably an error. As stated before, the "u"-shaped plate and the lever should both be plate. The two tubes (one brass and one steel) are only used at the extreme end of the lever arm. This is where the control cable and stay wire attach. On the Pup drawings, the "u"-shaped plate is a single piece of plate. The lever arm is made of two halves, welded together. The weld callout is indicated on the drawing. Check your drawings again. I'd be surprised if it's different.

My current project, the Bristol M.1C, has a "lever", or control horn as I would call it, similar to these. The "lever" is made in two parts, like a clam shell. The two halve are welded together like the Sopwith designs.

[Joe Perkel]

Originally Posted by Leatherhead

Joe,

I'm pretty sure the "lever" section is not tube. Does your drawing indicate this? If so, it's probably an error. As stated before, the "u"-shaped plate and the lever should both be plate. The two tubes (one brass and one steel) are only used at the extreme end of the lever arm. This is where the control cable and stay wire attach. On the Pup drawings, the "u"-shaped plate is a single piece of plate. The lever arm is made of two halves, welded together. The weld callout is indicated on the drawing. Check your drawings again. I'd be surprised if it's different.

My current project, the Bristol M.1C, has a "lever", or control horn as I would call it, similar to these. The "lever" is made in two parts, like a clam shell. The two halve are welded together like the Sopwith designs.

Ok,...now I got it!

I had misread this, the 18 G.M.S.T refers to the 5/16 tube bushing in the lever. Looking again with a magnifier, I now see the 22 G.M.S.P call-out for the two halves that I had previously missed.

Now it's clear,...thanks Leatherhead!

[Leatherhead]

Joe,

No problem. I'm glad I could help. That's what this forum is all about. I'm thinking of buying Rhino and would like to get your opinion before purchasing. Can you send me a PM with your phone number so we can talk?

[Joe Perkel]

Originally Posted by Leatherhead

Joe,

No problem. I'm glad I could help. That's what this forum is all about. I'm thinking of buying Rhino and would like to get your opinion before purchasing. Can you send me a PM with your phone number so we can talk?

Done deal,..just sent PM.

Thanks!

[drrivah]

Joe:
It would be good to know definitively what the specs mean, especially for critical parts.

In period engine parts lists, both materials (HTS=high tensile steel, for example; GM=gun metal; MS=mild steel) and heat treatment are often specified.

p. 273 of the 1925 Air Service Engine Handbook lists "A" through "V" postfabrication heat treatments:

Heat Treatment P:
After forging or machining:
1. Heat 1450-1500
2. Quench.
3. Reheat to 1375-1450.
4. Quench
5. Reheat to 500-1200 and cool slowly.

Heat Treatment T:
After forging or machining:
1. Heat to 1650-1750
2. Quench
3. Reheat to 500-1300 and cool slowly

Above are US standards. Not sure whether UK and US SAE heat treatment standard protocols were the same. I've seen lots of undefined designations in the LeRhone parts list found in the UK.

The control horns a subject to a lot of stress, so they may require special hardening/quenching by the heat regimens above.

Just a guess: check with a metallurgist or structural engineer.

Any engineers online?

-pete

[Joe Perkel]

Originally Posted by drrivah

Joe:
It would be good to know definitively what the specs mean, especially for critical parts.

In period engine parts lists, both materials (HTS=high tensile steel, for example; GM=gun metal; MS=mild steel) and heat treatment are often specified.

p. 273 of the 1925 Air Service Engine Handbook lists "A" through "V" postfabrication heat treatments:

Heat Treatment P:
After forging or machining:
1. Heat 1450-1500
2. Quench.
3. Reheat to 1375-1450.
4. Quench
5. Reheat to 500-1200 and cool slowly.

Heat Treatment T:
After forging or machining:
1. Heat to 1650-1750
2. Quench
3. Reheat to 500-1300 and cool slowly

Above are US standards. Not sure whether UK and US SAE heat treatment standard protocols were the same. I've seen lots of undefined designations in the LeRhone parts list found in the UK.

The control horns a subject to a lot of stress, so they may require special hardening/quenching by the heat regimens above.

Just a guess: check with a metallurgist or structural engineer.

Any engineers online?

-pete

Pete,

You've hit the nail on the head. Notice, that I am taking pause here in two places where fittings are concerned. 1) The spar to fuselage junction and 2) Airframe control.

1) Is not yet fully decided, I am conflicted between original and steel tube. Looking very carefully at what Redfern did with the Nieuport.

But, 2) is a done deal, so I can expect to faithfully reproduce these.

One nice thing about this CAD software is that you can do a surface curve analysis (cold molding) prior to the weldments and any heat treatments just to see where you are starting from.




Clearly, the top radius and the weldments impart stress, so standard stress relief is called for here. I suspect, the choice of material and the gage of each was deliberate even at this early stage in aviation.

You bring up an underlying concern of mine, loss of airframe control due to structural or component failure. Cockpit position in this aircraft is not conducive to reasonable egress so I am seriously considering a BRS system hidden in the turtle deck ala Ted Calahan's N-11. The original Baby had a small reserve tank in this location.

Not very sexy but hell, sitting there like a duck in thunder with nothing to do for the last few seconds, wouldn't be a nice way to depart!

[Leatherhead]

Joe,

Take a look at your drawings again. I've been comparing what you have presented to what is on the Pup and Camel drawings. It looks like the Pup's design is nearly identical with the Baby (makes sense); however, with the Camel, they added a thicker plate "sandwiched" between the two clam shell halves of the lever arm. Now the two tubes pass through three pieces of plate. They must have identified this area as a problem and modified the design.

By the way, the Bristol M.1C control horns are just about identical. They have two "clam shell" halves with a reinforcing plate sandwiched in between at the point were the control cable attaches. The Bristol Design does not have the tube. I like the Sopwith design. It makes sense.