$5,500 aircraft?

I'm thinking at this point we have a design split. One configuration would be an aircraft like an Aeronca C-2. For this, you could get engines, props, and instruments for about $1,300 and could probably stay under $4,000. Most likely, fabric covered wings. Probably wooden structure and this would likely need some type of bracing. Single seat, twin 10.5 - 12.5 HP two stroke engines. Hand prop start, no electrical system. Cruise 70- 80 mph. This would be a cost reduced version of what Fisher makes.

For something better, I'm thinking the price would have to go up to more like $6,000-6,500. For this, I think you could do aluminum structure and skin. We are looking at about the same HP with the single DLE 200 engine but it does have electric start. You would have to keep the weight down close to 600 lbs gross to have much climb rate. The engine would run about $2,200.

 

Strength per dollar is a useful number... for big aircraft and material comparisons.

For light aircraft it's fairly useless. Stiffness over density cubed divided per dollar wins since buckling, not strength is the failure mode.

What most people forget is that light but expensive material allows a lighter airframe, smaller engine etc. More expensive build materials is more than offset by a cheaper, smaller engine.

 

...And quite more expensive in Europe, compared to the U.S. (the prices in euros around here - in the hypertaxated UE I mean - must be multiplied and not divided by the 1,35 factor between the dollar/euro, as would have been normal).
Thus, I guess that approx. 7,000 euros would equal in Europe that 5,500 USD limit.

Anyway, your very detailed cost/weight/strenght analysis in various variants is excellent, brehmel62, and makes me think - as a wannabe HB AC-designer/builder - towards the most minimalist / simplest configurations.
Because for those I could use also some expensive materials (for example carbon fiber), since the total quantity would be small and - as Autoreply emphasised too - other connected costs would decrease (engines, props etc.)

 

It's not Oratex, is it?

 

No, Oratex is prepainted fabric.
Oracal is not fabric, it is vinyl film. Mostly used by sign shops for adhesive signs. Various names, I think Oracal is 3M.

Orafol Product Catalog at FELLERS

 

I was under the impression that the Oracal was applied on top of dacron fabric - not in place of it.
The idea being that the Oracal was actually lighter than the painting process, and allows for custom colors, printing, etc.

 

It looked like the Oracal on the fuselage was direct over the truss, no fabric. Fuselage cover isn't flight critical.
The wings had the Oracal applied to a fully sheeted foam skin cover. (Didn't get foam thickness, sorry)

 

Do you know what kind of foam?
I wonder what the advantages of that system are (strength to weight, cost and time savings, or?).

 

Pink styrofoam, I think. No structural advantage, foam just adds weight. The wing was smoother without fabric dips between ribs. But I don't see any advantage for an ultralight. He has new and different airframe each year.

 

Agreed, but I'd hate to be flying it if the fuselage fabric rips loose and blankets the tail surfaces.

Footnote: Covered fuselages enhance the ability to lose altitude in a slip, and some designs rely on the projected area of the rear fuselage for added lateral stability (effectively, acting like more rudder/fin area).

 

Don't tell the Alaska pilots that they can't slip their PA12's, cubs, taylorcrafts, etc. because of no fabric on rear portion of fuselage.

 

They can still slip the plane, but the effect is not as pronounced when there is no fabric on the aft fuselage. After all, the slip is meant to expose more fuselage area to the airstream to keep the speed down, and with no fabric, air passes through the structure instead of braking against the fabric.

Do any of the Alaskan bush pilots make a regular practice of flying with uncovered fuselages?

 

Not to my knowledge......wouldn't they be considered unairworthy without the fabric as originally built?

 

Only the EA-B Cubs are without fabric, probably.
Frank Knapp won the EAA Valdez STOL without fabric.

 

Frank is a very interesting fella who has been extremely generous to other STOL plane developers, with passing on info about his Lil Cub project.

Lil Cub did start out without fuselage fabric -



Then it got slats -



Then it got fuselage fabric -



Then it went to Valdez and won, see from 1:00 -

[video=youtube;F9EnVah07k0]http://www.youtube.com/watch?v=F9EnVah07k0[/video]

Frank says the big secret is -

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Lil Cub is very light ...

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Yeh, the Lil'Cub at Oshkosh I saw was the second. The first burned in his hangar. He built a new airplane and new hangar in a few months.

 

Yes, I've seen the build pics, it's quite a 'stripped to the bare bones' structure.

I was really just responding to the comment that he'd won at Valdez without fabric on the fuselage. For his win in 2013 the fuselage was covered but did he also win at Valdez some other time with the uncovered version?

 

I don't know about Valdez, but he did win at Airventure 2014 last week with the uncovered fuselage. I doubt it makes much difference either way.

 

Àññîöèàöèÿ Ýêñïåðèìåíòàëüíîé Àâèàöèè - Âèêòîð Äìèòðèåâ àâòîð Õ-14ä îòêðûë ñâîé ñàéò

=new pics of Dmitryevs X-12...