Cheap aircraft are simply impossible? :(

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nerobro

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That would be the cat's meow, but you'd have to sell a lot of engines to keep unit price within reason, even if manufacturing costs were rock bottom. An engineer once told me it took millions of man-lifetimes to develop the automobile engine.
Well, maybe. When the engines we're flying were developed, concepts like "tumble" and "flame propagation speed" were much less in their mind than "head temperatures" and "vibration". A high tumble, fast burn head, with good squish area would go a long, long way to raising BSFC. And they'd be essentially free. A high pressure oiling system, with full flow oil filtration would help. RPM are low... so it might not help, but you could go with dual cam in block, for better pushrod angles and more accurate valve timing. A girdle to allow the cylinders to support each other would be good. Or.. shock and horror, cylinders that are part of the block. And single piece heads. One of the keys to modern car reliability, is the reduction in parts.

................... But I need to build some stuff first.
 

Tiger Tim

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A girdle to allow the cylinders to support each other would be good. Or.. shock and horror, cylinders that are part of the block. And single piece heads. One of the keys to modern car reliability, is the reduction in parts.
Lycoming beat you to it. Quite some time ago, even.
https://en.wikipedia.org/wiki/Lycoming_O-145

Actually the A40, the other early flat four, had a similar fanatical approach to parts reduction. I wonder why both manufacturers strayed away from that? And VW, who also had their cylinders separate from the case halves when they could have been combined.
 

nerobro

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Nothing I've pointed out is "never been done". Just.. never all at the same time.

Also, almost all of this is "at the beginning" of production die casting, instead of sand casting. And all of it is before vacuum die casting.
 

lr27

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I think you can have a cheap, safe airplane without breaking the bank if you're more interested in being airborne than in going someplace fast. By safe, I mean reliable, requiring only moderate skill from the pilot, and maybe even being a little crashworthy. The last is helped, up to a point, by slower speeds. I suspect that some of the better ultralights are fairly safe if maintained and flown with caution by someone with proper training. No airplane is safe with a reckless or careless pilot.
 

choppergirl

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Choppergirl's Flying Circus ★★☠★★ AIR-WAR.ORG
VJ-23 hybrid glider using X box frame instead of spar. The fuselage is a sandwich of wood and styrofoam. Underneath, Lightweight transportation trailer built for it (green speed square sitting on it). Chopper IV tail rudder in background (Horse on it) - a Beujon Hybrid. Greg hates alluminum - he says it costs too much.

I asked Greg and he says he has $300 in materials so far in his VJ-23 lattice wing hybrid... he's one busy beaver, flooding me with pictures every day. I don't know how you can keep that kind of enthusiasm up to plow away on it every day... I get too depressed. Now back when I was hacking video games, sure, I could go months every day, X hours a day and think nothing of it... but then, you get to see the effects of your new code and changes on the scale across hours, days, or a week if it's a big block of new code, and test the results in real time. Painfully slow, to exit, make changes, reboot game server, go back in with game client... on the two old dual core machine I was using back then... but still. Building static things that just don't do anything at all until the end, which could be years off, doesn't much thrill me.

Yesterday's work, some sort of mount to fuselage and pilot cradle: 1, 2, 3

Anyway, sorry to interrupt you guys, you were talking about cheap airplanes being impossible or something like that... haven't been following along... I'll let you get back to that... I'm going to go back to watching freaky old retro computer videos online, the kind that use to fill a room and cost like millions. Personal computer on every desk you didn't need to share with anybody else... pfft! Those guys... what a bunch of nutters.
 
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nerobro

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I asked Greg and he says he has $300 in materials so far in his VJ-23 lattice wing hybrid... he's one busy beaver, flooding me with pictures every day. *snip* Building static things that just don't do anything at all until the end, which could be years off, doesn't much thrill me.
*snip*
Anyway, sorry to interrupt you guys, you were talking about cheap airplanes being impossible or something like that... haven't been following along...
Time, is money too. It's important to remember that. You're paying one way, or another. Greg's sending you updates, because he's investing the time (read money...) every day. The cost of airplanes is relatively small in materials, as they're light.

Projects taking years, is mostly a matter of not having the time to put in. For example, if you want to build fast, using big sheets of material, makes projects go fast. In my case, the first few hours of building my boat, I had a 3d hull shape. Greg is spending his time (money..) making popsicle sticks and gluing them up. You should ask him to show you the math on his spar.. that is a little concerning.

Cheap planes aren't impossible at all. There's stories of inexpensive, and cheap, planes everywhere. Many of those are cases of luck, or people with a lot more time than actual cash. That said, my idea of cheap, and yours, might not be in the same ballpark.

I know you want to fly badly. Why haven't you gone down the skypup path?
 

lr27

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snip
I know you want to fly badly. Why haven't you gone down the skypup path?
If memory serves, Choppergirl is fixing up a pre-existing VJ-24. Depending on what kind of shape it's in, my guess is that would take less time than a Sky Pup from scratch.
 

BJC

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VJ-23 hybrid glider using X box frame instead of spar. The fuselage is a sandwich of wood and styrofoam. Underneath, Lightweight transportation trailer built for it (green speed square sitting on it). Chopper IV tail rudder in background (Horse on it) - a Beujon Hybrid. Greg hates alluminum - he says it costs too much.

I asked Greg and he says he has $300 in materials so far in his VJ-23 lattice wing hybrid... he's one busy beaver, flooding me with pictures every day.
I would like to learn more about the design of the “X box frame instead of [a] spar.”

Could you get Greg to post some information here, or provide a link for more information?

Thanks,


BJC
 

pictsidhe

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I'm hoping to make my Hurricane a kit. Initially, it was a 'me' project. But large amounts of monocoque heat formed from 8x4 or 10x5 sheets of inexpensive material has made me bold. Designing as a kit has really slowed down design, though. I'm spending a lot of time trying to make it easier and cheaper to build. Just building it would be quicker...
 

Little Scrapper

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I'm hoping to make my Hurricane a kit. Initially, it was a 'me' project. But large amounts of monocoque heat formed from 8x4 or 10x5 sheets of inexpensive material has made me bold. Designing as a kit has really slowed down design, though. I'm spending a lot of time trying to make it easier and cheaper to build. Just building it would be quicker...
Have you scratch built one individual airplane for yourself from start to finish? You may want to consider it because that in itself is a monumental task and will be a good education in it's own right.
 

Hot Wings

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I know the is the homebuilt "airplane" forum but the thread says cheap "aircraft". So what is wrong with this approach? One bolt to trailer and you can stack a bunch in a 20 foot shipping container. fetch.jpg
 
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