Raptor Composite Aircraft

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Dexacare, Mar 28, 2016.

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  1. Aug 21, 2019 #1301

    rv6ejguy

    rv6ejguy

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    These have been very good for years: https://firewall.ca/index.php/camdrive-500-psru/

    The DOHC V6s are going to be close in weight to an LS3. Might as well de-rate the rpm and make the V8 last a long time. With a turbo and low boost, 3500-4000 rpm will make the requisite power.

    And yup, should have had a Conti 550 or Lyc. 540 turbo to start, expensive as they might be. The test program won't get far with this abomination in the back.

    They haven't even begun to start finding the major problems with this design.
     
    Last edited: Aug 21, 2019
  2. Aug 22, 2019 #1302

    Victor Bravo

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    The only Velocity I saw recently that had the air scoop on top, where the guy said the cooling worked acceptably, had two huge vortex generators or vertical strakes on the fuselage in front of the NACA scoop.

    It is possible to push a shopping cart backwards, and it is possible to put the basement of a house on top of the roof, and it is possible to force a square peg into a round hole. So it is also therefore possible to force the cooling system to flow air from the low pressure point toward a higher pressure. But whyyyy?

    Small "armpit" scoops would provide a greater volume of higher energy air than the same (or anywhere near the same) size scoop on top of the fuselage. Add to this the "receding" or decreasing contour of the fuselage shape at that point behind the cabin and it gets worse... then throw in any climb angle and it gets worse... then throw in the flow separation from the wing roots, windshield contour, etc. and it gets worse.
     
    Last edited: Aug 22, 2019
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  3. Aug 22, 2019 #1303

    Venom

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    One can hope
     
  4. Aug 22, 2019 #1304

    Andy_RR

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    There's a lot of that in this project...
     
  5. Aug 22, 2019 #1305

    Tiger Tim

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    That sort of thing is a big priority on the prototype, the people he’s trying to market to don’t have the patience for a long development of an airplane that looks externally finished.
     
  6. Aug 22, 2019 #1306

    FarmBoy

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    Those FFAE units look decent - though they out to be at almost $30K full up! And actually heavier than the AutoPSRUs when you add all the parts up.

    Please provide specifics rather than saying "have had failures in the past...". Reading here http://www.autopsrus.com/ckfinder/userfiles/files/Home Built Airplane Response.pdf there do not appear to be any issues with the current design. And I'm actually a fan of the clutch - especially as their complete package with clutch is lighter than the FFAE unit (albeit limited to 400HP). The harmonic dampening and safety benefits of the clutch are a plus in my book.

    Yes, turbo V6's would be close in weight to a non-turbo LS3. And as either would have to run at a lower "de-rated" RPMs with a PSRU, both would benefit from a reliability perspective (the LS3 perhaps more so with lower boost). And the engines I mentioned are designed to be boosted and provide more torque and HP at a lower RPMs whereas a stock crate LS3 would require modification for tuned boost applications increasing cost, time, or both.

    It's really about design/application goals. For instance, if you took take cost into account, the differences in MTBF from a 2.3L EcoBoost 4cylinder and an LS3 may be a wash from a TBO/repair/replacement cost perspective. And the 100+ lbs saved and increased efficiency of a 2.3L would add up over a few thousand hours of flight time (likewise though perhaps smaller savings from a V6). Pushing less weight through the air aside, either of the newer factory boosted engines are more efficient than the LS3, lowering fuel costs and increasing range (it all adds up).

    In the end, either engine would be cheaper than the PSRU so its all a matter of perspective (or preference).
     
  7. Aug 22, 2019 #1307

    rv6ejguy

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    The clutch only handles TV below the engagement point, does nothing in the operating range. There was a clutch disintegration and fatal crash involving one of those drives. At least one other drive loss and forced landing on my friend's RV10 a few years back. They had some seal issues causing serious oil loss. Like I said, could be fixed by now. I'm not sure what other safety benefits there are with this design. Just more to go wrong. Nobody else uses them on certified aviation gearboxes.

    As I said, none of these other GBs are cheap- Robinson, EPI etc. I'm not going to pay this sort of money for a single speed GB, but maybe other folks will.

    The LS will work fine with a turbo with no other mods- 400 hp at 40 inches at 4000 rpm easy. Maybe want forged pistons if you want to run it leaner in cruise. Check the weight of DOHC V6s, doubt if it's even 30 pounds less than an LS.

    Yup, lots of other engines you could use but then you have to adapt gearboxes to them. 4 and 6 cylinder engines have more TV issues to contend with too. Most newer engines are DI and we've discussed why that might not be the best idea.

    Nothing much cheaper than an LS turbo attached to a Ballistic drive and an electric prop.
     
    Last edited: Aug 22, 2019
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  8. Aug 22, 2019 #1308

    FarmBoy

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    While not necessarily lighter, that's probably true. And I have nothing against a small block V8 - especially an LS - they're awesome engines.

    There aren't many options until more direct drive capable power plants become available. At least, after 20 years, DeltaHawk finally looks like it may actually get certified. An Achates Power engine may be an option in a year or two - right now the engine is just in a prototype F150 (http://www.trucktrend.com/features/1811-opposed-piston-engines-making-old-technology-new/) but if you look at the specs it appears to be capable of at least 220HP at a prop friendly RPM and could likely go closer to 300 with a little extra boost (http://achatespower.com/wp-content/uploads/2018/02/Achates-Power-SIA-2017-paper.pdf). Should be exceptionally smooth as well being an OP engine. The engine will be available in larger displacements too with not much % weight penalty as sizes increase. Since they are quite a bit smaller than an equivalent displacement production engine they must be lighter though I could not find any reference to engine weight for the 2.7L. As they already have a partnership with Cummins to produce engines for the Army, its just a matter of time before they are also commercially available. Though electric is an eventuality in automobiles, ICE and hybrids will be bridging the gap for quite a few years.

    Turbo-normalization is another issue. I came across this little fellow - http://www2.eng.ox.ac.uk/engines/uniceg-presentations/v-charge - which looks like it would be a very interesting option for any (sea level) stock turbo engine combination to provide automatic variable boost according to desired output and prevailing input conditions. while not as efficient as staged turbos, it appears to have a very small impact to BSFC. This would likely be a better option for Peter to use than his current secondary.
     
  9. Aug 23, 2019 #1309

    rv6ejguy

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    The DeltaHawk isn't affordable- something like $90K.

    New engines are not available.

    Peter needs to dump the diesel which will get rid of the need for the second stage turbo. SI engines produce more power and torque per unit displacement and per unit MAP. The diesel is just the wrong choice to operate at FL250 due to the huge pressure ratios required to make any power up there.

    Turbos are elegantly simple, reliable, easy to control boost and become more efficient as altitude is increased. No reason to use any crankshaft driven forced induction.
     
  10. Aug 23, 2019 #1310

    BoKu

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    Checking the Vans store, it looks like RV-10 builders are paying $48k for an IO-540. Add $10k for a turbo and intercooler, and $4k or whatever for an RV-10 tail kit, and you're probably still well below whatever that Audi setup will end up costing by the time it delivers actual power.
     
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  11. Aug 23, 2019 #1311

    harrisonaero

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    Truth here. The only reasonable move for the $2.7 million owed to investors. Staying with the current abomination is negligence. If he wants to continue his engine development he must do it on a proven airframe, likely a twin.
     
  12. Aug 23, 2019 #1312

    flyboy2160

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    I saw what you did there.....I think many people would scam Vans like this; hence the disclaimer on their website says the discounted engines are sold only to those who have purchased a complete kit. Has anybody here tried your scheme?
     
  13. Aug 23, 2019 #1313

    rv6ejguy

    rv6ejguy

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    The thing is, Peter doesn't have a clue what's he's up against with the current propulsion system. He thinks it will all be ok.

    He clearly doesn't understand turbocharger matching, heat exchanger theory, the significance of torsional vibration or how a PSRU should be designed and properly attached to the engine. How could he? He has no background in any of these areas or in aerodynamics, stability, structures or systems. His engineer friend Mark should be turning his back on this whole crazy design as it doesn't look good on him either at this point. A coupler being used which isn't rated for the rpm, torque or angular deflection to be seen in this installation? A PSRU not mounted rigidly to the engine?

    I see another failure coming in ground testing as they start pounding on this setup at cruise and takeoff power levels for a few hours and I sincerely hope the test pilots or Peter does this before they try leaving the ground. Better to find out there than at 200 feet over the trees.
     
    Last edited: Aug 23, 2019
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  14. Aug 23, 2019 #1314

    Vigilant1

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    Listing the Vans price for a IO-540 as an example of what that engine might cost is not "scamming Vans." Nobody is suggesting that anyone cheat Vans. It's just a readily available example of a price for that piece of hardware. Don't be insulting.
     
    Last edited: Aug 23, 2019
  15. Aug 23, 2019 #1315

    BJC

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    If there truly are orders for the Raptor, then Raptor Aircraft could get a deal with Lycoming almost as good as Van’s.


    BJC
     
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  16. Aug 23, 2019 #1316

    rv6ejguy

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    Unfortunately the pressurized aircraft requires a turbocharged engine and either model of turbocharged Lycoming 540 or Conti 550 would be well over $65K even at discounted prices. That may be just the price of admission into this realm though.

    A well developed automotive substitute would take a while to test and prove by an experienced person or team. Those costs would add up but I believe if done correctly, could still come in at half of what the aero engines cost, once you reach some reasonable quantities to amortize those development expenses. For this concept to really fly, the powerplant and PSRU really have to be bulletproof though- like your car. You might need a network of trained mechanics to work on these things. Most buyers/ builders would not have the knowledge or wrenching skills and most A&Ps might not either. I am sure Peter never considered this angle. Certainly few people would be qualified to work on the present Audi diesel setup as it currently stands.

    The reality therefore is that you might need a certified engine to make the whole concept viable and it will cost what it costs.
     
  17. Aug 23, 2019 #1317

    AdrianS

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    One of the things I find interesting reading about ww2 era engines is the test logs. These engines were designed and built by experts, and many went on to a long and productive life, but you read so many test failures on the way there.
    Even the best in the business needed several iterations before a new engine/psru had all the bugs ironed out - and they always tested new engines in proven airframes, and new airframes with proven engines.
     
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  18. Aug 23, 2019 #1318

    rv6ejguy

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    Yes, engine development projects intended for production aircraft are for engine guys, not amateurs, ditto for PSRU development. Yes, you can do it by trial and error but it will take years. Even professional engineers and people with years of practical experience learn new things and don't get every aspect right the first time around.
     
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  19. Aug 23, 2019 #1319

    Toobuilder

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    The P&W R2800 was arguably one of the most successful aircraft piston engines ever - but it took a long time to get there. The TV issues alone almost scrapped the concept.

    The bulletproof example found on the wings of DC-6's flying families all over the country was a long way removed from the prototypes which ate themselves on the test stand with alarming regularity
     
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  20. Aug 23, 2019 #1320

    flyboy2160

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    Chill out. I didn't intend to insult anybody. The opposite is true! I think it's a great scheme! I'd use it myself and resell or part out the tail kit for an even bigger saving! Alas, Vans is wise to this. Otherwise, you could start a business buying the discounted engines and reselling or parting out the tail kits...
     

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