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Weight Saving Ideas?


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In going over the past newsletters and reading about how people have been trying to save weight on the plane, there have been some interesting ideas put forward. It seems one of the areas is the firewall construction. The Carbon BID solution did very well in the tests between using Aliminum, Steel, and Carbon.


What kind of weight savings can be expected if you choose the carbon route over the plans?


Has anyone ever considered titanium? Titanium is light weight, has a very high melting point, and doesn't corrode. The main drawbacks to using titanium are that it's expensive, and it's fairly hard to work with. It also doesn't get along well with cad plated hardware, which is typical of AN and NAS parts. You can pick up surplus Titanium at: http://www.titaniumjoe.com/ and for the size required on the firewall, shouldn't run you more than $300.


It seems any weight savings in the rear is a good thing. What are the thoughts on this and OTHER weight saving ideas?



Tis far easier to ask for forgiveness than for permission.

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Try doing a seach on this forum for words such as "carbon" or "spar." Although you've not mentioned the spar yourself, you'll find that it's usually one of the first things folks come up with for carbon-reinforcement, or modification. This often leads to lengthy discussions on hypothetical modifications of other parts, such as bulkheads or firewalls.


Not to discourage you, but you'll find this topic is nearly beaten to death, with two main opinion camps; the "build it to plans" camp and the "I'm not afraid to try something new" camp. I tend to favor the former, since the thread often dies after someone posts a good reason to stick to the plans methods and materials.


I think the general consensus is that for the most part, any advantages (which tend to negligible) of redesigning or modifying major components or structural items is outweighed by the risk of introducing unacceptable behaviors or failure modes to other (perhaps unrelated) components on the aircraft. Build it to plans and you can rest assured that it will do everything it's supposed to. Try something different, and you're sailing (or perhaps flying) without charts. You'll see what I mean when you find the relevant threads. Good luck.

Evan Kisbey

Cozy Mk IV plans # 1114

"There may not be any stupid questions, but I've seen LOTS of curious idiots..."

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I'm in a similar position to yourself, sitting on a Pacific island doing my homework on how to build a Cozy.

I can't say from experience, but I have learn't this.

Burt Rutan, who designed the plane the Cozy is an enlarged version of, is a real minimalist. He says "If you can pick it up, drop it, and it falls to ground, then it's too heavy to go in one of my planes." He's obviously exagerating, but you get the point. If you look at the gauges in the Boomerang, there are 5 from memory, and each one is as big as your watch face.

Nat Puffer has done an excellent job of designing a wider version of Burts lightweight EZ.

I'm sure you could change some parts and materials, but you'd have to be confident with your structural analyses.


Regarding the Titanium, I have here an article about the SR-71 Blackbird. In its design and manufacture Kelly Johnson, and the Skunk Works team at Lockheed broke new ground using titanium.

Cadmium, as you say, which plates some tools is incompatible with Ti, and will cause failures, they had to make special tools, normal screws and bolts corroded aswell. The chlorine in tap water corrodes Ti, they had to wash the beast in distilled water. They had to make special drill bits and use a special lubricant for the holes, and any welding was carried out in a nitrogen chamber. Even marker pens were banned from the workshop, because of the Flourine they contained was causing corrosion.


Sounds a bit risky eh?

Best of Luck with the planning.




The Coconut King

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Very creative thought! One that i have not seen brought up yet.


The only problem i see is that the Basic firewall of 1/4 inch high quality plywood coverred with 2 layers of glass on each side is very light. The extra layers of glass come in when this is tied into the plane structure, which would still have to be done.


enjoy the build/start the build(he he he)



maker wood dust and shavings - foam and fiberglass dust and one day a cozy will pop out, enjoying the build


i can be reached at



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In My former life in the offshore buisness we used titanium in a plant for preparing seawater to be injected into the oilreservoir. Exept for some none fireproof plastictypes and gold it was the only material that was not corroded by sodium hypochloride (I think it was)

I cant imagine that it would corrode when used in an aeroplane.

Great material; light as aluminum, strong as steel, shiny like chrome.For welding you would need a special chamber.I never had the welding certificat for titanium,but you sure need to be skilled to do the job.For bolting must be used either titanium bolts or insulated bolts.(nylon washers and tube)


Plane will be called `Hugin`

After Odins raven

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