DarkAero

Discussion in 'Composites' started by cluttonfred, Dec 27, 2019.

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  1. Jan 17, 2020 #121

    lr27

    lr27

    lr27

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    It's a non-starter if they have to modify expensive commercial equipment which has lots of un-needed capacity. These crazed hobbyists will also have to be very clever. It won't be feasible if they do everything the way Boeing does it.
     
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  2. Jan 17, 2020 #122

    Jay Kempf

    Jay Kempf

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    Not saying anyone has to modify an existing machine. But good luck making a hobbyist grade CNC machine for cheap that does any of this stuff. Are you assuming that something like Fusion360 has a tape laying engine? Solve the software problem first. Then think about building a machine.
     
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  3. Jan 21, 2020 #123

    Staggermania

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    I keep forgetting about this thread, then I see Dark Aero and click on it forgetting that the thread is not about Dark Aero.
    The OP is “still waiting for someone who want to be the Volkswagen Beetle and apply these (composite) technologies to making an inexpensive, easy-to-built, easy-to-fly kit plane for ordinary folks.

    Perhaps this thread should be renamed?
    Maybe “Are inexpensive composite aircraft kits possible?”

    Just my 2 cents
    Thanks
     
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  4. Jan 21, 2020 #124

    blane.c

    blane.c

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    Not true because it is not an apples to apples comparison. If I buy an old champ then it has to have an inspection by an A&P and signed off by an IA most all the parts have to be certified, it isn't just the expense either which would choke a horse it is the time as well. If I build my own plane I can work on it myself as the builder and even modify it as well and in my time frame as well. Therein lies the magic of homebuilding otherwise sure a champ was my first plane and another could well be my last.
     
  5. Jan 21, 2020 #125

    blane.c

    blane.c

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    Re-drives implies more power out of the same already taxed powerplant, perhaps unwise? Another thing is that you don't really want more power because it cost more money, more gas, more maintenance, and it still won't last as long either. What you want is miles per gallon just like a car and those who think different have enough money that this thread is just a curiosity. Miles per gallon, well since it is commonly said it takes four times the horsepower to go twice as fast then it is just common sense it takes four time the gas too. So what is wrong with taking twice as long to get somewhere at one quarter the cost? Use a tube ground pounders will just think it's rain.
     
  6. Jan 21, 2020 #126

    Marc Zeitlin

    Marc Zeitlin

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    Actually, PSRU's imply wanting the same power at a different RPM - it's a set of gears, not a power increaser. All it does is give you more torque at lower RPM - power stays the same, minus losses in the PSRU. The engine doesn't know the difference.

    I don't know who commonly says that, but power scales (all else being equal) as the cube of the speed, not the square. Eight times as much power to go twice as fast. Drag scales as the square of the speed. This only applies on the higher end of the speed scale, not below max L/D, where induced drag dominates. But I digress.

    My 2004 Subaru Legacy wagon gets about 24 sm/gallon, driving an average of 40 - 60 mph in city/highway driving. My COZY MKIV gets about 22 - 23 sm/gallon (of admittedly 50% more costly 100LL fuel) flying at 190 - 200 mph. So I'm getting essentially identical mileage, going 3X as fast, on a direct route. But it costs more because I have to use 100LL. Still pretty economical, and you can build a COZY MKIV for <$60K if you're a good scrounge.
     
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  7. Jan 21, 2020 #127

    blane.c

    blane.c

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    Well again apples to apples it just isn't so. The reference was to VW engines which on redrives are generally going to be turned higher rpm and more power as would many others so there is a difference to the engines in question. I mean your saying that people are only going to use a redrive so they can use a longer propeller, maybe some but certainly a stretch to think all.

    60k for a Cozy MKIV seems a good value to me. If it could just accommodate 3 smaller engines instead of just the one, hmmmm.
     
  8. Jan 21, 2020 #128

    blane.c

    blane.c

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    This thread started with the premise of low cost composite structures for aircraft? So naturally everyone went to carbon fiber, I guess because it is the cheapest? Maybe some other material may better hit the cheap bullseye and yet still be light enough to be acceptable? Just asking maybe for a slight weight penalty fiberglass or another product could be cheap, cheap enough to take a weight hit. You know sorry dude your to fat I only take my skinny friends for a ride. But what the heck it'll fly?
     
  9. Jan 22, 2020 #129

    BJC

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    Post #2 in this thread pointed to a fiberglass kit that once had been available for less than $10,000, with a claimed competed airplane cost of less than $25,000 using a Corvair engine. The airplane was successful, but the kit business was not.


    BJC
     
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  10. Jan 22, 2020 #130

    blane.c

    blane.c

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    I looked it is an interesting plane, and the site posts todays date so by that appears to be maintained. I wonder why no takers?
     
  11. Jan 23, 2020 #131

    103

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    That is the same thing Rex Taylor related to me around 1987 when my Cygnet was a new born and Rex Bought the rights to Sisler's design. "If you want to make a small fortune in experimental aviation, start with a big one".
     
  12. Jan 23, 2020 #132

    cheapracer

    cheapracer

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    I have never not heard it said for any of the multiple areas of business I have been involved in.

    But for some reason reminds me of my Wife's Credit Cards that were stolen 2 years ago, I haven't reported it because the thief is spending less than my Wife was ....
     
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  13. Jan 23, 2020 #133

    litespeed

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    Given the speed of change in CNC etc machines and the falling prices.......


    If you design it right for the available tech you can now access, a lot of the labour is done by electrons. Its all about design for the absolute quickest easiest way to assemble a flying machine. That should be composite.

    Composite and its abilities, tech to cut, mould making etc just keeps improving. As does accessible computer power and programming.

    I do not see it as a unreasonable quest to beat a vans in price or even sonex. And it could certainly be done to take less hours to complete.


    The magic of Vans and Sonex is they make it seem simple and easy, it just a lot of time.
    They have great support and instruction.

    But all those parts and rivets add up.

    You want something that is a 200-300 hour build max and that includes the 51% rule. Then even at $35,000 you have a winner for a basic aircraft. Less would be better.

    People are time poor, easily distracted and have lots of other stuff that precludes a long build.

    Its all about maximum use of cheap tech, falling prices for anything airframe related ie composites including vacuum and resin tech.

    The cost side of the metal one can also leverage such savings but is still stuck at been a riveted aircraft. That takes a long time to build.

    A design optimised for min part count, ease of accurate assembly, and tech doing most of the actual labour at the factory can be done. You just have to design it to do that.

    Unless you talking big sales the molds do not have to be mega pricy. That's old school thinking.

    We are not trying to create a super performance or point design just get in the air quick and cheap. But still nice enough not to get backyard billies homespun looks.

    The idea is minimal finishing, everything positions exactly as needed. Very few parts to join etc..

    The biggest point of sale will be lack of complexity of build and low labour involved.

    It must be approachable to build and create a experience people enjoy and is not years of slog and low confidence in completion.

    Needing as cheap and simple instruments as James Weibe has produced or latter day cheap I pad style. It does not have to be a $5000 panel. $2000 would be possible day vfr. And surely a $10,000 one is excessive.

    Simple as possible high wing enclosed cabin. 80 HP to 120 HP, but 65 if a lighter engine fitted.

    90- 130 cruise knts or a different lower speed version wing.


    But it must be designed to optimise all the available tech and reduce time to create at all processes.

    It does not need to be the perfect for its mission as far as speed, looks ,features or strength.

    It just has to be good enough to be cheap, easy and cheerful.


    But airframe to airframe a well designed composite should be able to beat a metal rivet machine in price for 2020.



    But black metal thinking whilst it has some advantages does miss a lot of potential.

    Although flat layups offer a great deal in speed and low cost.


    A flatish sides aircraft does not have to be a drag monster. And moulding is dirt cheap and can be accurate. Just have to think a total design to meet the design goals.

    Talk of Airbus or Boeing tech is missing the point.

    It can't be designed for big dollar tech, it just has to be good enough.

    Its a cheap basic car not a luxury or fast one.

    But design is everything. It lives or dies on every step being designed for a total goal. Not costs sunk by a traditional aircraft maker. And traditional thinking.

    The first time a marketing or MBA type gets near it
    ...


    It could be another money vacuum.
     
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  14. Jan 24, 2020 #134

    pwood66889

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    "A design optimised for min part count, ease of accurate assembly, and tech doing most of the actual labour at the factory can be done. You just have to design it to do that."
    And all the rest. Well said, mate.
     
  15. Jan 24, 2020 #135

    blane.c

    blane.c

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    The problem is sheet goods and framing materials standards, try so much as building a house without studs, joist, beams, plywood, sheetrock and fasteners, hardware and joining plates/hangers. No standards no building. No standards no airplanes. Until a compilation of standard materials to choose from exists, it's all talk. We can build from steel tubing it comes with standards, Spruce and plywood we have standards, sheet metal and bulkheads we have standard, Composites are still at the raw material stage. How many people saw down a tree and make there own longerons and plywood? Look what becomes of standardization, sure many houses look alike but many more are unique. If you know what the standard will do you can deal with it. Much of composite to many is limp rags and goop.
     
  16. Jan 24, 2020 #136

    lr27

    lr27

    lr27

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    There is no law that says you have to abuse an engine just because it has a redrive. On a slow airplane, a redrive may permit a smaller engine with equal or better performance. Without drawing more power from it.

    If people are,going to be foolish with a redrive, taking away,the redrive just means they'll find another way to be foolish.
     
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  17. Jan 26, 2020 #137

    blane.c

    blane.c

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    I just bought an Ioniq plug and drive (advertised) 52mpg on engine alone and 119mpg in HEV (which lasts as long as there is enough battery power to amortize with the engine and then of course back to 52mpg) but any way I would like to see closer to 50mpg than 25mpg in an airplane. So it becomes a speed vs power vs the elements thing. Obviously an airplane doing 100mph is going to have larger percentage loss in real mpg than a 200mph aircraft with any significant headwind, so to slow isn't necessarily any more fuel efficient than to fast is considering real world conditions. But I think there is a practical place were the airplane is fast enough and were the airplane's power consumption amortize to get close to the goal. Some of the Sonex with the VW based engines get around 50mpg at around 10,000ft (at least advertised) and some of the Vari-Ez's types can do better than that higher up (not that most people want to) but how much fuel used to get there I am not sure of. They seem to cruise along at a good clip.

    So considering naturally aspirated engines going up to at least 12,000 ft and above you will be working with at most around 64% power or less of that available at sea level, and we can lean, lean of peak to maybe 1/3lb (1/18 gallon) per hp hr using electronic fuel injection so at 180mph (some wind) @ 12,000ft we can afford (for 50mpg) at most 64.8hp so if we started with a 100hp on the ground we would be about right except not many airplanes will do 180mph with 64.8hp even at 12,000ft. And especially rare are those that will do it 2 place. So go higher starting out with more hp (and weight) or go slower with less hp (and less weight) are the two options I see. … 120mph (a little less wind) @ 12,000ft @ 50mpg allows 43.2hp @ 1/18th gallon per hp hr. I think getting past the sfc argument for a moment that it is realistic to build an airplane that carries two people and cruises at 120mph with about 40hp more or less available at that altitude. In my mind it is far more realistic a proposition than making the airplane heavier and going higher from especially the financial and time to build aspects.

    Or put a 985 on your home built bi-plane push the throttle to elbow lock full rich and weeeeeeeeeeeeeeeee, **** the torpedoes.
     
  18. Jan 26, 2020 #138

    cheapracer

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    The Morgan Sierra build impressed me a lot, even with being aluminium and needing to drill all the holes yourself, it's still a sub 500 hour build. My plane is somewhat similar in some areas, but less parts and pre-matched holes, shooting for sub 300 hours because if people don't complete stages that are visibly successful, that they can stand back and see what they have accomplished that day, they can be easily distracted after say 6 months on it.

    Low parts count on an aluminium plane is easy, I don't know how some of the companies manage to make theirs so complicated, look at a Thorpe T18 plans one day to see how not to do it, if you see a T18 and know the owner built it himself, shake his hand for the effort he went through to get there.

    My rear fuse is 4 main pieces, 2 sides, upper and lower, easily duplicated in composite using sheetmetal molds, same with the bracing and gussets, or rather the bracing and gussets could be molded as single pieces lowering parts count further.




    IMG_20191126_155834_resized_20191126_094714944.jpg

    IMG_20191126_155851_resized_20191126_094714497.jpg

    Tail 4.jpg
     
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  19. Jan 26, 2020 #139

    blane.c

    blane.c

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    This looks simple like a VP except using aluminum and rivets instead of wood and glue.
     
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  20. Jan 26, 2020 #140

    cheapracer

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    This is the prototype, it's even simpler for the pre-production version, i.e. things you realise as you go along, and can make things simpler.

    I run a separate CAD model and make the changes to that one as I go. Simpler and lighter without loss of strength, or simpler and stronger without increase in weight.

    But, and relevant to this thread, figuring how I can do it all later with 2D composite. Also in mind is my CNC Router that's coming that will be able to mill out the various shapes out of the composite panels.
     
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