Sopwith Baby Project

[j ferguson]

Joe,
since you can do this without having your shop completed, assuming the First Officer will allow you to do it at the kitchen table, why not make an epoxy saturated panel and one merely varnished and weigh them?

I strongly suspect that you are going to find that epoxy is very heavy - and its use will not allow you to reduce panel thickness.

I can't imagine that your plane will spend a lot of time outside, but West is not UV resistant by itself. We use a lot of it on the boat for "ruggedizing" wood construction like chain lockers and so forth. I always put two coats of Wests on the marine plywood and then two top-coats of opaque poly-urethane paint so that the epoxy won't break down. My experience is the paint top-coats aren't needed in surfaces that don't spend much time in the sun.

On the other hand, if you have leftover weight budget from using a lighter engine, AND you can make the balances work........

If it were me, I would make some simplified mockups for destructive testing. I think you can accurately anticipate what will happen in terms of deterioration over time, but to appraise the sort of reactions different construction methods of these floats will have on/in the water and especially on landing, it might be good to do some trials, unless, of course you do exactly what Sopwith did.

Cheers, John

[Joe Perkel]

Originally Posted by j ferguson

Joe,
since you can do this without having your shop completed, assuming the First Officer will allow you to do it at the kitchen table, why not make an epoxy saturated panel and one merely varnished and weigh them?

I strongly suspect that you are going to find that epoxy is very heavy - and its use will not allow you to reduce panel thickness.

I can't imagine that your plane will spend a lot of time outside, but West is not UV resistant by itself. We use a lot of it on the boat for "ruggedizing" wood construction like chain lockers and so forth. I always put two coats of Wests on the marine plywood and then two top-coats of opaque poly-urethane paint so that the epoxy won't break down. My experience is the paint top-coats aren't needed in surfaces that don't spend much time in the sun.

On the other hand, if you have leftover weight budget from using a lighter engine, AND you can make the balances work........

If it were me, I would make some simplified mockups for destructive testing. I think you can accurately anticipate what will happen in terms of deterioration over time, but to appraise the sort of reactions different construction methods of these floats will have on/in the water and especially on landing, it might be good to do some trials, unless, of course you do exactly what Sopwith did.

Cheers, John

John,

I lost an extensive reply due to time out!, and now it's quite late!

The gist of it was, thank you for sharing your marine experience and I agree with the assessment of excessive weight gain.

Every time I start to stray from original, Nick's devotion to authenticity and the results make it's own case quite well.

I dont like the float re-design, something intangible is nagging at me. I can't quite nail it down.

Thanks John!

[Joe Perkel]

John,

I posted the composite layup from my sub on the float page of my website.

Main Floats

See if you are "bothered" by it as well, or if I am not seeing the forest.

Thanks!

[drrivah]

Joe:
The float detail, images and CAD views on the website are first-rate. Great to see this level of care resurrecting the details in modern formats for the rest of us to enjoy.

Keep up the good work.

-pete

[Joe Perkel]

Originally Posted by drrivah

Joe:
The float detail, images and CAD views on the website are first-rate. Great to see this level of care resurrecting the details in modern formats for the rest of us to enjoy.

Keep up the good work.

-pete

Pete,

Thank you for the kind words and well wishes.

Many others whose opinions regarding the documentation and sharing of historical aircraft details, have contacted me via email to mirror your sentiment. Literally people from all corners of the globe.

I have to say that my original intention was simply to get as much help as possible in making the project a success, and to have a little fun in web design and CAD work as well.

In the year since inception, this "Preservation" and "Documentation" of history sentiment has gotten my attention, and I began to structure the web-site accordingly about six months ago.

The long term plan, barring the unforseen, and should I be successful in completing the project, is to have the first mass produced military aircraft by the Sopwith Company both brought to life, and digitally documented for posterity.

With a little luck maybe both, the plane and the web-site could outlast me. Who knows, we'll see. I only regret that the U.S. didn't have anything substantial aircraft wise in WWI.

Thanks again Pete!

[j ferguson]

Hello Joe,
I've looked at the details of your alternate float design and think I need to leave an engineering appraisal to one of our engineer colleagues. Was the alternate design engineered?

Frankly, I would never ever include any inaccessible volumes in something that is going in the water, and this is what you'd get with those foam inserts. Even though localized structural damage could be visible on the outside of the float, I would be much more comfortable being able to inspect every connection and joint.

The original floats are built a bit like Old Town wood canoes, lots of ribs and relatively thin skin. The beauty of this design includes redundancy, simplicity, and perhaps some flexibility, where some localized impact load can be absorbed over a larger portion of the structure. But I remind you that this is a likely ignorant opinion.

Finally, here is an idea that might not be entirely nuts. If your weight budget can afford it, why not fill the compartments with ping-pong balls? they might provide enough flotation to keep you rightside up if you do get leak.

Also, they can be removed to inspect the interior - using a vacuum cleaner. You could even put numbers on them and run a lottery. (sorry).


John

[lake flyer]

Another possibility , dingy sailors usually have some "watertight" compartments in their boats to prevent sinking in case of a capsize .

Since "watertight" compartments usually are not "watertight" it is common practice to add some form of bouyancy .

Plasitc bladders , blocks of foam or large plastic soda bottles .

Maybe something like that would be usable in your floats, to keep from sinking in the case of a rupture .

[Joe Perkel]

here is an idea that might not be entirely nuts. If your weight budget can afford it, why not fill the compartments with ping-pong balls? they might provide enough flotation to keep you rightside up if you do get leak.

Also, they can be removed to inspect the interior - using a vacuum cleaner.

John,

This is why I participate in this forum,… brainstorming!

Not at all nuts and worth some consideration, I’ve seen a 3 bedroom houseboat down here buoyed by milk jugs. Certainly it would be better then filling with foam, and talk about an easy extraction method. You would have to ensure that there could be no shifting or settling of this mass. Computing the amount per volume should be a snap with the software.

Downside: you may miss a small water intrusion that could shift on take off under all of these balls.

I've looked at the details of your alternate float design and think I need to leave an engineering appraisal to one of our engineer colleagues. Was the alternate design engineered?

The design is a suggested one from a float designer / manufacturer in Canada. I am not familiar with his credentials other than many years of field experience. However, that experience most certainly did not include these “sled type” floats. This is resurrected technology.

The original floats are built a bit like Old Town wood canoes, lots of ribs and relatively thin skin. The beauty of this design includes redundancy, simplicity, and perhaps some flexibility, where some localized impact load can be absorbed over a larger portion of the structure.

Not at all ignorant, you are addressing the issue of “hard points”, (localized stress failures concentrated by the structure itself). Here you verbalize part of what’s on my mind. What did Sopwith know that has been lost to time, but was incorporated into the reengineering of the later generation of floats post machine #8163? Brisfitworks prior words of “trusting in their engineering” are ringing a bit loud about now!

Thanks John!

Thanks also Lake Flyer.

[Joe Perkel]

John,

I couldn’t resist the temptation, and found a box of 72 count ping pong balls @ $25.00 per box.

Sopwith Float volume = 19.5 cu ft / 33,696 cu inch
Avg Ping Pong Ball = 1.75 cu inch

2 Floats = 38,500 / 72

= 534 boxes @ $25.00

= $13,368 total to fill these up!

I figure maybe 3 to 4 k (30%) discount to find them wholesale somewhere.

Looks to me like I’ll likely assume the risk then!

Oh well!

[j ferguson]

Well that's pretty expensive air, isn't it.

It's a little like the Titanic. Without something like the ping-pong balls, a long slit in the bottom spanning your compartments would sink that float. This does make putting the kevlar cloth around the bottom and sides very attractive.