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The slightly different Harley Thread

Discussion in 'The Pub' started by incitatus, Mar 15, 2007.

  1. I've had my fun in the 'Harley Riders' thread, so I thought I'd even things up a bit by showing yous all this piccy;


    Now given that an engine failure is a reasonable way to get dead if you muff the forced landing, someone must believe that Hardley Dangerous make a reliable engine, and the FAA must agree or it would never get the tick to fly. Hell, I might even fly it given the chance.......You don't see many (any?) planes powered by Jap motorcycle engines, although there are a few with Guzzi and BMW bike engines, and back in 1920 some brave lunatic flew on a Henderson bike motor. That is not to say there is anything wrong with say an R1 engine, its just that most modern motorcycle engines, though very high tech and capable of putting out huge horsepower, are not designed to operate continuously at high power like airplane engines. Aircraft must fly for hours on end at a steady 75 percent power, motorcycles usually operate well below that level with occasional bursts of higher revs. Where they do, like racing, they just don't last very long.
  2. F A S C I N A T I N G, George!!!!!!!!!!!! Love the name too?

    But, is a Harley engine any more amenable to long periods of continual revolutions operation than any other bike engine? I wouldn't have thought so, although certainly it could exploit its torque and lower revs more easily?
  3. Yeah but there are guys around who fly ultralights! Need I say more.
  4. I think that is essentially the point, direct drive aircraft engines normally operate at less than 3,000rpm, looking at that re-drive belt, I'd (roughly) visually estimate that was about a 2-1 ratio, so I'd guess that motor is only doing 5,000-6,000rpm in the cruise, probably less. An R1 motor would have to be (a) geared higher to get the required torque, and (b) revving much higher. Low stress is the thing in aircraft engines, above all else.

    A few years ago, Honda was working on an engine with Teledyne, builders of one of the most widely used aircraft engine ranges, (Continental), it had been installed in some aircraft and tested, but the Honda aircraft engine disappeared without trace. Maybe the crossover isn’t all that simple.
  5. So are we saying that Harley Engines, while useless on a bike, are suited to a plane? :)
  6. 20 years ago I would have agreed with that, but things have moved on. The modern ultralight will equal or outperform most single engine GA trainers, e.g. http://www.mcp.com.au/sting/ 140+ Knots on 100HP, retractable, and CSU options.
  7. :LOL: :LOL: :LOL:
  8. It probably weighs/costs the same as a Harley.
  9. Consider this. The Aprilla RS125 125cc 2 stroke engine is produced by a company called rotax who also mass produce light aircraft and ultralight engines.
  10. they only put that engine in cause it sounds good, it doesnt handle or accelerate very well :)
    but give it a rev mate!!
  11. Do you have to wear a helmet in some planes, inci?

  12. bmw have documentation saying that they do not want any of their motorcycle engines installed in aircraft. There are categories for which no engine certification is required as well...

    this doesn't mean anything other than it was probably fairly easy to find - is it really any different to a japanese 1500/1800/2000cc pushrod twin?

    An interesting point for you lot as well - an R1 engine can produce the same torque as these twins - it only produces more power because it spins faster. Nothing stopping you from gearing and running one of them at the same equivalent torque as the twin, just at low revs. HD do seem to make some fuel efficient engines though.
  13. Well, it is a stationary pump engine, gotta be durable right? :LOL:
    Personally, I'l take a Jabiru six (in an ultralight) or a Conti O 470 thanks. Hmmm, wonder if I could put one in a bike?
    I ned to start flying again. Thanks Inci. :cry:

    Regards, Andrew.
  14. The flying equivalent of the XR1000. That motor's only redeeming feature is that it attracts chicks, yet someone fits it to a single seater. Go figure.
  15. its the art of playing hard-to-get sir chairman :LOL:
  16. Probably not in most ways, but it does not have an integral gearbox, making it easy to fit a re-drive belt. The unitary construction of the R1 motor and its equivalents would make them much more complicated to adapt for that reason alone.

    Personally I'm old fashioned and prefer an aircraft engine in my aircraft, however, the most commonly used bike engines in aircraft are low revving horizontal or 'v' twins. The VW car engine is common, as are a 2 cylinder 'half VW', the Subaru boxer (originally a failed aircraft engine design anyway), and the Mazda Rotary. BMW obviously wasted the paper saying they didn't want their engines used in aircraft, because literally hundreds have done so with an excellent reliability record almost since the engine was first designed, it is second only to the half VW in popularity among the twins.

    You are correct in saying that there are categories that do not require certified engines, but even in the experimental category the airframe/engine combination still needs to be approved for flight by a certified engineer, and again by the FAA after 25 hours of flight testing. I realize this does not earn the engine a TBO like a certified one, but surely it says a bit more than just "fairly easy to find".......

    ZX1200, the Jabiru uses Yamaha motorcycle pistons, just about it's only component not made in Bundaberg.