Sopwith Baby Project

[Joe Perkel]

Originally Posted by RobW

Joe,
I found a reference book you may be interested in... the original title was: Aeroplane Structures by AJ Sutton and Capt. Laurence Pritchard, 1919. Reprints can be purchased online under the title WWI Aircraft Airframs, Structures, & Components.
It is essentially a wooden aircraft engineering book. Way over my feeble brains capacity... discusses methods of construction, testing, measuring loads, etc...

thought you might be interested.

Rob

Rob,

I had thought that I might already have that one in my library, but I looked and did not. A quick look at the online version on google books and I see that it is a particularly good reference as you noted.

First editions of these books in good condition are hard to find, and make for a nice collectors piece in themselves,... I do get them on occasion. I was lucky to find one and picked it up just now.

Thank you very much Rob!,... this one will be both useful and interesting.

[Joe Perkel]

I need a bit of interpretation help for the aft center section to main plane junction. The forward spar hardware is pretty much straight forward and I posted them on my site as completed, but the aft ones are a bit more complex.

Specifically, I am having a bit of trouble interpreting design intent for the 16 g backing plates shown for part "D". Below is the image of the drawing and the models below.

My suspicion, is that these plates serve the joint rod in some manner.

Any help here would be much appreciated.

[Nick]

Hi Joe,
Your drawings are brilliant as usual.
I'm guessing the backing plate in the drawing is a reinforcing washer. They're usually brazed on although it says in your plan to weld.
If you look at the Snipe thread post #234 page 24 you'll see a photo of a spar fitting on the centre section which is typical Sopwith. Most of these fittings have the joint rod hole reinforced with a washer. Sometimes its just a large washer and other times, like this fitting, it is joined either side like a dumbbell shape (prior to bending).
Once brazed on the inside of the fitting the spar needs routing for it to slide over.
On some fittings the reinforceing washer is brazed on the outside of the fitting.

Cheers, Nick

[Joe Perkel]

Originally Posted by Nick

Hi Joe,
Your drawings are brilliant as usual.
I'm guessing the backing plate in the drawing is a reinforcing washer. They're usually brazed on although it says in your plan to weld.
If you look at the Snipe thread post #234 page 24 you'll see a photo of a spar fitting on the centre section which is typical Sopwith. Most of these fittings have the joint rod hole reinforced with a washer. Sometimes its just a large washer and other times, like this fitting, it is joined either side like a dumbbell shape (prior to bending).
Once brazed on the inside of the fitting the spar needs routing for it to slide over.
On some fittings the reinforceing washer is brazed on the outside of the fitting.

Cheers, Nick

Hi Nick,

I suspected as much, but was thrown off by the off center placement of these 16 g plates. The Pup drawings show a washer here quite clearly. I think that I might be missing a detail call out here.

If I recall, it was a 1" washer on the Pup. When I get home tonight then, I will groove the spar accordingly and add them to the inside of part "D".

That's 3 layers of material here then, 16g x2 and 18g x 1,...thats quite a bit. Also the shape of the spars on the ends with the rounded "ball in socket" joint is a bit strange. Interesting also, a specific call out for solid back spars on the top planes. The "ball in socket joint" may or may not be a remnant of the wing warping mechanism on the earliest Schneiders,..or it may be a specific design intent, I cannot be certain.

Thanks a bunch Nick, I needed a second opinion here!

[lake flyer]

My first thought when I saw the rounded end on the spar was wing warping , but the Baby doesn't do that .

I think you are quite right it was a carryover from the wing warping Tabloid . ( probably had some spars left over with round ends , LOL. )

[Joe Perkel]

PREPARATIONS CONTINUE PLEASE STAND BY

[Joe Perkel]

.....or how the economy adversely effects us all.

As some of the members are aware, I am delayed by a large housing project that has taken more than a year, and now well into 09. This largely due to a funds misappropriation, late last year by my contractor, which thankfully, has now been resolving adequately for some months now via exchanged labor. He avoids jail, I avoid refinancing,..all is well. As I like to say,.."Any day that you are standing on your own two feet and breathing,..is a good day!"

In the meantime, I get to take advantage of the delay. Case in point the photo above. Some may recall that I had originally intended to use modern coverings, Well,...take a good look at this,..I think not!!

[j ferguson]

Joe,
Somewhere in the Hadith, the collection of Mohammed's observations on many of the conditions of life, is the statement that

"Building is the most foolish thing that eateth up the wealth of a believer."

I'm sure he meant buildings not airplanes, though.

And no, I wasn't taught that in architecture school.

[Maxim08]

Joe,

Looking at your picture of the Jenny leads me to a question.
Clear doped linen (CDL), or cotton or even Ceonite for that matter; what is the correct application of doping with specific regards to UV protection? How many coats and of what?

Balancing between British and US published standards from the 10s to the 40s call for anywhere from 6 to 16 coats of which 2 or 3 are aluminised UV protectors followed by colour topcoats. I haven't found any specific reference to clear UV inhibitors.

The Memorial Flight team in France used an Akzo Nobel product as a top coat on their D VII which left a gloss finish which doesn't appeal to me.

Does anyone have expertise regarding clear UV protectors specifically for aircraft fabric use?

Regards,
John

[Dogtail2]

Joe

The only way that Jenny looks like that, is because it has no UV potection whatsoever. Thats OK, providing you dont mind having to recover it every 5 years.