Any rotary powered BD-5s under construction or flying?

    Jim Rudholm


    The [Mazda] Rotary is too big for a BD-5. Rather it's too heavy. The
    BD-5 is
    designed around a 3 cyl 2-stroke engine. The design weight was about 150
    pounds. Less than 50 hp. Several have been built using the Rotax 2
    cycles. If a proper single rotor is produced, it could work.
    Bill Jepson


Jim,
Actually, the BD-5 was originally going to be powered by a German Hirth
two cylinder two stroke air cooled engine. That engine was unreliable
and was Bede's downfall which brought on bankruptcy.
The Japanese Zenoah three cylinder two stroke engine mentioned above
might have saved him but it came along to late. Corkey  Fornof (he did
the BD-5J flying in the James Bond movie Octopussy.) swears by the Zenoah.
Numerous engines have been tried with mixed results and several failures.
Today the three engines offered by  Ed "Skeeter" Karnes of  Bede-Micro
Tech are a new and improved Hirth, a Solar T-62 turboprop and for those
with deep pockets the JET!

http://www.bd-micro.com/ <http://www.bedemicro.com>

Most alternate engine installations added a substantial amount of weight
to the airframe. Original designed empty weight was 350 lb. There are
many flying BD-5s that almost DOUBLE the original weight estimate. The
Honda EB3 installation, one of the more successful substitute engine
packages, puts out 110 hp but tips the scale at 137 lb. with turbo, rad
and fluids.
My BD-5 uses a Honda but I'd like to convert to a rotary. A 2 rotor of
100hp weighing around 100 lb. would, IMHO, make an ideal package.
John Lewis
N501BD

John,

The new Rotary Aircraft Engines Skypower 65 (single rotor) version of
Rotamax comes close to your ideal.

http://www.rotaryaircraftengines.com/enginemodels.htm


"Rotamax Skypower 65 Aviation Engine - Ultralight Market
Max Horsepower            Cruise Horsepower     Fuel Burn    
65 hp @ 6,500 rpm     55 hp @ 5,500 rpm     2.2 - 3.1 gph    


Weight       Price w/Gear PSRU     Overnight Rebuild
110 lbs     $7,995     $2,495

New dual spark, dual ignition, carbureted and water cooled aviation engine.
This engine produces as much horsepower as a 2 piston two stroke Rotax 582.
Its TBO is 500 hours, 200 more than the 582. But it has several hundred fewer
parts to wear out, or fail, or need replacement, and it does not vibrate. Buy
it for four-stroke reliability, no vibration, regular gas fuel economy, low
emissions, and extended life span. You will realize a much lower total cost
of ownership. ASTM compliance testing is under way and will be completed by
about May 15, 2008."

The 110 lb weight includes 20 lbs. for the PSRU.  You can figure the tradeoff vs.
the BD-5 belt reduction.  In December I had an email exchange with Nate Oldham
at RAE, and he said the turbo charged version of the 65 puts out 100 hp and the
turbo adds 12 lbs.  So without the PSRU and with the turbo, you have 100 hp at
102 lbs.  :-)    Those weights at the time did not include the radiator, hoses
and coolant, and I suspect they still don't.  The Hornet info should be able
to add some detail to total weight.

Joe Cook  (considering the Skypower 65 for my Sky Raider 1 to replace
the Rotax 503 and ex-owner of a BD-5 kit long ago.)

-
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site. http://www.rotaryeng.net
Youtube key word UTUBPLEASE
Copyright 1998-2008 All world wide rights reserved.