Corsair/Spitfire hybrid

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Will Aldridge, Oct 16, 2010.

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  1. Jan 16, 2012 #341

    Vigilant1

    Vigilant1

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    Yes, Tracy's site isn't as current as it used to be. He's still very active in "the scene."
    Conversion costs could vary a lot depending on how "fancy" you'd like things to be. The Mazda cores themselves are readily available and you'd probably find a good one for very little money. You want to use new (good) apex seals (Mazda brand name ones are among the best). Teflon-encapsulated O-rings are worth the price, and a few other odds and ends. The place you'll have to spend money is the PSRU. As shown on Tracy's site, his are about $3500. They show up on eBay and Barnstormers occasionally (along with abandoned engine projects) so that could be a low-cost way to go. As I mentioned, Paul Lamar and others are working on lower-cost and lighter-weight PSRU designs, but they aren't ready today. The Mazda stock Mazda induction system is much too heavy and big, but you don't have to spend a lot of money to replace it. Tracy produced about 160 HP in his 13b for many years using three simple Mikuni carbs. I think some folks are flying with Holleys with a separate leaning block (for altitude compensation). Tracy makes a very nice engine monitor, but if you want to go the caveman route you don't need it. Okay--so I haven't given you many numbers. If you're willing to scrounge for an engine and wait for a used PSRU, buy used radiators (or use "stock" sizes), etc, but needed to pay for exhaust pipe fabrication, etc, I'd guess you might be able to do everything for $5000-$6000. But it's easy to spend as much as you want!

    The Bruce Turrentine video is worth buying if you are serious about doing the rebuild yourself.

    Some people just buy the first old core they find for a few bucks just to experiment with pulling the engine apart and seeing how it works. At the very least they wind up with some useable spare parts for later, parts to practice on (drilling the P-ports, etc), parts to take to their EAA meetings and airshows for demonstrations, etc

    You may already know this, but here are some other notes:
    -- PSRU gearing: Although Tracy advertises the 2.17:1 ratio as being good for the RX-7 engines and the 2.85:1 as being best for the Renesis (i.e. RX-8) engines, many people believe the 2.85:1 ratio is also best for the RX-7s. The engines redline at (IIRC) 8000 RPM, so one wouldn't have a problem turning 7000 RPM for takeoff, etc. With a 2.17:1 ratio and a "full size" prop, the tip speeds start to get inefficient at that engine speed.
    -- As with any auto conversion, doing the details right is key. I'll bet more of these engines fail in aircraft use due to the use of auto-standard rubber hoses, auto-part worm clamps, and non-AN oil fittings than from anything fundamental to the engine.
    -- P-Port: Fish around Paul Lamar's site for more on drilling out the housings, sealing up the water jacket and the unused side ports, etc. There's a You Tube video on it, I think.
    -- Ross redrives: These were sold before Tracy got started. They are well made, but have some known issues. AFAIK, they aren't subject to sudden failure, you just need to monitor the gear lash and a few other points. If money is an issue and if you find one for the 13B at a low price, you might consider it. It might not go 2000 hours, but it might be a good "starter" PSRU while other designs mature or you search for one of Tracy's PSRUs at the right price.

    Stuff to think about . . . "and the Mazda goes Hmmmmmmmmmmm."

    Mark W.
     
    Last edited: Jan 18, 2012
  2. Jan 18, 2012 #342

    topspeed100

    topspeed100

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    I actually bumbed into this same cache recently when I added some elliptical ( bulged wing an extra angle in the leading edge ) planform on my wing....it started etherically to feel like a Spitfire..test pilot said the Spitfire II is not a good name for it..not original. Prandtl wing theory just makes all planes look like Spitfire. If you add a tad too small elevator then you have a Spitfire. I just saw a video of 90% scale Spit and it says Spitfire was pitch sensitive...just like the pik-26 which in fact has 25% too small elevator at 0.27 TVC.
    Any plane that starts to look like a Spitfire might actually be a pretty good flier, just make sure it won't become too heavy and complicated.
    Does anyone know the TVC of the real Spitfire ?
     
  3. Jan 19, 2012 #343

    Will Aldridge

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    I've been playing around with the components Paul Lamar has sent me (engine and redrive w/ starter). Hope he doesn't see that I am fooling around with mounting it plugs up(apparently he doesn't like that at all). I have read the pros but not the cons, so if anyone can enlighten me please do so. So far the major thing I notice is that the exhaust doesn't conflict with the motor mount at all. It does if mounted oil pan down. I know the exhaust configuration is probably wrong and I need a muffler, but again I was just playing around.

    plugs up 13B and Redrive.jpg

    You can also see that I have redrawn the cowl. The radiators won't fit under there so maybe I'll make it more like the Mustang and put a belly scoop on it.

    new cowl top.jpg newcowl.jpg
     
  4. Jan 19, 2012 #344

    Vigilant1

    Vigilant1

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    Could the radiators go at the back, behind the engine? There needs to be enough room for the air to escape, but it looks like you've got some real estate back there. You'll need room for the oil cooler, too: The Wankel sheds 2/3rd of it's heat through the water cooling, 1/3 through the oil cooling (of the rotors).

    Plugs up: The knock on this is (IIRC) that the water cooling system isn't set up for it and that pockets form in places around the engine where water vapor or air collects. I have no educated opinion on the extent to which this problem manifests itself, but I do know that the plumbing is easier if the plugs are up (exhaust, induction, etc) yet most of the installations I'm familiar with (including Dave Leonard, Tracy Crook, etc) prefer not to go that route. They may have a good reason.

    Paul Lamar has written a book on cooling rotary engines in aircraft. It includes design tips for ducting, etc.

    Spitfire, Corsair, now Mustang. Work in a Zero, a Bf-109 and a Yak and you'll have all the bases covered!
     
  5. Jan 19, 2012 #345

    Will Aldridge

    Will Aldridge

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    The accessory drive package was not included in the model Mr Lamar sent, so there is less room than there appears to be. I know that some of the radiators could be fit under the cowl I just don't think they all could.



    Well the mustang was already represented in the vertical stab it's just getting a little more representation. I don't know if it's obvious to anyone but me but I used the FW-190 as inspiration for the canopy design.
     
    Last edited: Jan 19, 2012
  6. Jan 22, 2012 #346

    Aircar

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    With fixed spatted gear and an inverted gull wing surely your closest WW2 aircraft match is...-- the Stuka ..?
    Putting in a large chin radiator would add to the effect as well , some junkers flaps, a little olive drab paint and this and that and you could terrify the neighbourhood with dive bombing and a couple of those air driven sirens on the wings. just a thought anyway -- and wouldn't an inline engine better suit the cowling shape rather than a flat four ? The local Cobra used a Mazda rotary conversion and geared reduction plus a darbon Bolly three blade prop (VP) --don't know if he is still selling them .
     
  7. Jan 22, 2012 #347

    Will Aldridge

    Will Aldridge

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    I guess you missed most of the last 2 pages worth of the thread? I have decided to ditch the Corvair engine and go for a Mazda 13B Rotary. Several reasons, first more hp, second the Corvair was actually a little lite for cg purposes (if I have to add weight up front I'd prefer to have it be in the form of more hp)and, cost. A bare bones 13B would be about $1-2k less than a bare bones Corvair. Admittedly I do like the idea of a narrower cowling. As far as the Stuka goes I gotta admit that comment raised the hackles a little. These may be fighting words but I never really liked German planes as far as their aesthetics goes. They all seem kinda ugly to me. And the Stuka definitely isn't at the top of my list of good looking German planes. I think the bend in my wing is extreme enough that it more closely matches the Corsair. One of the main things I want to accomplish with this plane is for it to be really beautiful. And making it Stuka esque would defeat that purpose.
     
  8. Jan 23, 2012 #348

    Aircar

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    It was a tongue in cheek comment but the "aircraft recognition" handbook would probably have the Ack Ack on you if you were flying around in 1940 over the white cliffs of Dover --distinctive combination of features that .... and I had scanned the thread --why NOT an in line engine for an orginally in line engine aircraft replica ? wasn't the Stuka an Argus engine ? only guessing --for a Corsair you must have a radial and the big circular cowl to go with it--check out the Rotec perhaps (Rotaries are shorter and wider in general and you can't have the exhaust stacks were they ought to be for scale --a flat six is possibly the worst shape match .
    The Jaguar Vee twelve was the engine of choice for Merlin or Allison-Packard replicated fighters but are rare as now and too big likely (W.A.R. was the firm I think or Thunder engines later but there are so many more straight sixes or narrow vees around now ).

    A local firm I did some work for was supposedly buying a full scale fiberglass Spitfire advertised in Argentina and planning to use a Chrysler V 10 in it --it turned out to be some sort of scam although the aircraft existed --they have a P51 now underway built from Falconair plans and made as a plug only for making molds off .

    Back in the 70s when we got relaxed regulation for ultralights I toyed with the idea of a 3/8 scale P38 -twin in line two strokes,handed props,tuned pipes down the booms etc and using bits from my other aircraft for the pod and engine cowls --got the drawings and all the stuff I collected for it --if you want a WW2 fighter look alike and cheap engines then I would look at such a thing still.
     
  9. Jan 23, 2012 #349

    Will Aldridge

    Will Aldridge

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    I'm not opposed to an inline engine at all, but have yet to find one in the right hp/weight/price range (120hp+/250-300lbs/
     
  10. Jan 23, 2012 #350

    Jan Carlsson

    Jan Carlsson

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    Will,
    What about the VW Golf diesel, that a couple of Finns put in a PIK 2X and a C-172 with I think it was 135 and 180 HP, I don't know the weight right now. but very possible thing. and not a 100k $ thing.
    they are on the u-tube
     
  11. Jan 23, 2012 #351

    4trade

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  12. Jan 23, 2012 #352

    Will Aldridge

    Will Aldridge

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    Looks like part of my last post disappeared into the ether after it was posted. Should say my engine requirements are 120+hp/250-300lbs/
     
  13. Jan 23, 2012 #353

    Jan Carlsson

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    Looks like that diesel Cessna is 30 kg heavier then one with a IO-360, if that is all engine or also barlast, I don't know.
     
  14. Jan 23, 2012 #354

    Matt G.

    Matt G.

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    Haven't read the whole thread in awhile to see how you feel about a radial, but I think the Rotec R3600 is 150 hp and 275# including accessories.
     
  15. Jan 24, 2012 #355

    Will Aldridge

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    The Rotec is way too big for the current design. My Firewall is a little over 26" high and 25" wide. The Rotec is about 34" in diameter. Just doesn't fit and I want a narrow cowling.
     
  16. Jan 25, 2012 #356

    fadec

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    LOM PRAHA s.p. :: Piston Engines - All services in the top quality

    Production went into limbo a few years ago, not sure what current status is but used ones are cheap and can still be overhauled, might be worth considering for a one off design, bragging rights for having a supercharged engine, rumoured to be reliable in service
     
    Last edited: Jan 25, 2012
  17. Jan 25, 2012 #357

    Bill Ladd

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    Someone on the Chilton builders email Yahoo group recently took delivery of a new Walter LOM four-cylinder. IIRC, he's in the UK and had it shipped from CZ
     
  18. Jan 25, 2012 #358

    Will Aldridge

    Will Aldridge

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    Just for grins I took 5 minutes and added a radial cowling that looks like it came off the Bud Super Corsair.
     

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  19. Jan 25, 2012 #359

    Jan Carlsson

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    I have always liked the Corsair, but yours looks better, With the Rotec engine, you will have a cowling like the Howard Hughes. racer H1, not that bad.
     
  20. Jan 25, 2012 #360

    Hot Wings

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    It was kind of hard imagining how you would improve the looks of your project, but I think you've done it!
     

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