Sopwith Baby Project

[j ferguson]

Finally, you don't need 38,000 ping pong balls. it looks as though it takes 16 ping pong balls to displace a pound of water. there's a lot of freeboard on your floats as well there should be, but the floatation is only being provided by the bottom 2/3s. I figure if the baby weighs 1700 lbs, fewer than 27,000 will be needed and the cost will now be less than $2,700.

you would continue to have full inspectibility, AND, if you decided they weren't really needed, t would be easy to get rid of them.

But I concede that it is a nutty idea.

John

[Joe Perkel]

Originally Posted by j ferguson

Finally, you don't need 38,000 ping pong balls. it looks as though it takes 16 ping pong balls to displace a pound of water. there's a lot of freeboard on your floats as well there should be, but the flotation is only being provided by the bottom 2/3s. I figure if the baby weighs 1700 lbs, fewer than 27,000 will be needed and the cost will now be less than $2,700.

you would continue to have full inspectibility, AND, if you decided they weren't really needed, t would be easy to get rid of them.

But I concede that it is a nutty idea.

John

John,

In the amateur to amateur experimental aircraft business, no idea is "nutty", so long as it's offered in the spirit of improvement and or safety. That is clearly the case here. Your ping pong ball idea, caused me to ask the following questions.....

- Why always voids (compartments) and no floatation, going back to the beginning?

- Why three compartments?

- What is the most likely causal factors of damage? (Avoidance via design, and or procedural).

- Should I do something about the shortfall of reserve of buoyancy, or leave well enough alone.

Clearly, there was much value to me in the ping pong ball idea.

Thanks!

[David Paule]

I thought of another alternative... adding more watertight bulkheads. You'd need more inspection ports, too.

[j ferguson]

Joe,
After reviewing all of the above, I realized that I've been pitching something I wouldn't do myself if it was my plane.

There is a great advantage to having two main floats. It is very unlikely that they would both leak at the same time.

I''m also skeptical that you are going to get a big leak on landing that isn't a disaster in a lot of less pleasant ways than having the plane sink gently beneath the waves which is what the extra flotation is intended to prevent.

Accordingly, and if it was my plane, I would not have any additional flotation.

I would paint the aviation equivalent of plimsol lines on each float. If you can see the sides of the floats from the cockpit, then I would paint them on both the fuselage side and the outside of each float. Assuming the plane sits level (in roll) in the water, both sets of marks should agree. If not, there's a problem.

I can't believe you are ever going to drag this up on the beach. More likely it will either be moored, or sitting on its cart. So abrasion and rock damage seem unlikely.

Finally, I would do as one of our colleagues has suggested and build two sets of main floats.

A number of projects on the boat have been "faked" or mocked up with cheap plywood to check "proof of concept" with the idea of building the real thing with better materials and more care, once I was confident with the design. Once in a while, the mock-up wound up being the final project, dinghy cradle for example.

In your case, I would do my best on the first set of floats to make them usable but then introduce whatever refinements or innovations come to mind on the second set. I would also install the diaphragms shown on the Sopwith drawings.

As to problems with water, I remember a college room-mate who had been a "stewardess" on an Alaskan airline that flew Catalinas in the late fifties - they were serving locations in the Aleutians that didn't have airports and he was male despite the job title which he said was non-negotiable through some perverted sense of humor on the part of the operator.

He said that his principle job was to pump water out of the fuselage and floats before every flight - and there was a lot - mostly via missing rivets in the hull.

I don't think this is going to be a problem for you.

[Joe Perkel]

Originally Posted by David Paule

I thought of another alternative... adding more watertight bulkheads. You'd need more inspection ports, too.

David,

This is the consultants proposed design changes, with the exception of the extra transverse bulkheads, which I added. My idea being increased rigidity because of my concern of his deletion of the 3" rib spacing. He cited "hard points" as a potential issue. If I eliminated the lightening holes, you would now have two extra watertight compartments. Also, look what happens to the hand holes now.

Not being my area of expertise and unsure of his design, I am inclined now (again) to "run home to mama" and go with the original design for authenticity and relative piece of mind.

However, the discussion has prompted me to seriously consider going with solid ply webs for the bulkheads in leu of canvas for three reasons.

- I am convinced that they considered this to outlast the service life of the aircraft

- I would not be able to get to those canvas bulkheads so easy for replacement.

- I'm not convinced of their integrity in a pinch.

Thanks David!

[Joe Perkel]

I''m also skeptical that you are going to get a big leak on landing that isn't a disaster in a lot of less pleasant ways than having the plane sink gently beneath the waves which is what the extra flotation is intended to prevent.

John,

Crossed my mind as well. This in direct corelation to what Bryan says here.....

We look at the possible Failure Modes, the Effect and how Critical that is to the system. Ranking the critcality means you can then make design decision with some confidence that you know what is the most important consideration.

I can't believe you are ever going to drag this up on the beach. More likely it will either be moored, or sitting on its cart. So abrasion and rock damage seem unlikely.

I do intend to "beach it" as a preferred method of arrival, much more preferable to trying to approach a dock. I envision approaching a typical boat ramp with handlers pre-positioned at the wing tips, or shut down prior to arrival.



Incidentally, that flat four and faux rotary we see on the other thread, is looking mighty purdy about now!!!

Finally, I would do as one of our colleagues has suggested and build two sets of main floats.

Considering this as a possibility.

He said that his principle job was to pump water out of the fuselage and floats before every flight - and there was a lot

I can expect both seepage and condensation to accumulate water, although I expect some thing less than aluminum floats.

[brinesharks]

Originally Posted by Joe Perkel

I do intend to "beach it" as a preferred method of arrival, much more preferable to trying to approach a dock. I envision approaching a typical boat ramp with handlers pre-positioned at the wing tips, or shut down prior to arrival.

I assume you will use the orignal beaching wheel set up?

[Joe Perkel]

Originally Posted by brinesharks

I assume you will use the orignal beaching wheel set up?

Bryan,

Yes, I intend to build that, I do have the drawing for it. But, I am suspecting it will be used more for nostalgia, and photo ops.

I envision use for the Baby to be somewhat limited, and well planned. For one thing, the original had a 2.25 hour endurance, this with a reserve tank behind the pilot. I don't quite yet know what I will do about the main fuel tank, if it ends up a bit larger or what? A long way from there. Still, I can see a limited range developing.

So Florida has 3 public use seaplane bases with fuel available. One is Jack Brown's seaplane base which shares space with the Lakeland airport, an hours drive from my assembly site.

So this means, I have to buy or rent a hangar at that airport, and then dolly the plane to the ramp at the seaplane base. The dolly, likely being a modern version with a hitch for my car, or tractor tug.

Now, I can fly to various lakes in central Florida within range of Lakeland, with many having soft white sand beaches and or grassy shores,... "Now where did I leave that dolly"?,.."Oh yes, back at the airport"!

So you see, I'm quite limited as to where I can go with this aircraft but, that's OK. Anything further, like say Key West, would require well planned fuel stops with waiting handlers at each location. Not your typical cross country bird, but well worth it I would think!

Can I tempt you with a nice pretty Nieuport!

[brinesharks]

Originally Posted by Joe Perkel

Bryan,

Yes, I intend to build that, I do have the drawing for it. But, I am suspecting it will be used more for nostalgia, and photo ops.

I envision use for the Baby to be somewhat limited, and well planned. For one thing, the original had a 2.25 hour endurance, this with a reserve tank behind the pilot. I don't quite yet know what I will do about the main fuel tank, if it ends up a bit larger or what? A long way from there. Still, I can see a limited range developing.

So Florida has 3 public use seaplane bases with fuel available. One is Jack Brown's seaplane base which shares space with the Lakeland airport, an hours drive from my assembly site.

So this means, I have to buy or rent a hangar at that airport, and then dolly the plane to the ramp at the seaplane base. The dolly, likely being a modern version with a hitch for my car, or tractor tug.

Now, I can fly to various lakes in central Florida within range of Lakeland, with many having soft white sand beaches and or grassy shores,... "Now where did I leave that dolly"?,.."Oh yes, back at the airport"!

So you see, I'm quite limited as to where I can go with this aircraft but, that's OK. Anything further, like say Key West, would require well planned fuel stops with waiting handlers at each location. Not your typical cross country bird, but well worth it I would think!

Can I tempt you with a nice pretty Nieuport!

Good to see you working out your missions profile

Using a tug is a good idea. Having to have four or five strong people to get you in and out of the water is a challenge. A 2.25 hr endurance isn't bad - I think you will find it surprisingly fatiguing flying something like this. No shelter from the wind or noise. It will be exciting and nostalgic but not particularly comfortable. My posterior wouldn't take more than 2 hours on a wooden seat either!

Although the Nieuport (3?) float plane is very pretty - Australia is not really the place for a specialised float plane. Lots of beautiful places to fly but next to no infrastructure. I'll have to stick to the Avions de chasse, Nieuport type 17 with wheels.

I'm hoping to fly to some of the fly-ins and air shows around the country. A real bonus will be those days when the air is calm and the sun is sitting on the horizon. A dawn or dusk patrol is something that I'm really looking forward to - particularly if I can manage to chase around Sheppo's Albatros!
Overall though I don't expect to do more than 50 hours or so a year in it.

[j ferguson]

I had imagined that you would operate the Baby much like a cross-country sail plane or balloon - with a ground crew. One of the less happy events that could happen is to lose air-worthiness in a strange place where the plane cannot be stored safely inside pending repairs.

So, one of the really neat opportunities you have is to design the towable trailer which is highway legal and can be used to extract the Baby from the water without dragging it (gasp) over the beach

Remember,

"The first rule of flying is that it is an expensive way to go somewhere that you can't afford to be once you are there."

You really can't control the first part of this, but you could the second with proper ground crew and trailer. BTW, can the Baby on its trailer clear bridges and be less than 8 feet wide?

What a wonderful wonderful project you are planning.

best, JF