zsmith3rd(at)earthlink.ne
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 Posted: Fri Feb 23, 2007 9:06 am Post subject: 701 engine choices |
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do not archive
Robert,
This may not answer any of your questions.....probably just add flames to an already hot topic.
Obviously, like airframe choices, the selection of an engine is partly a personal issue and partly dictated by constraints imposed by the design.
The 701 originally had a 65 HP 2-stroke Rotax. As builders began wanting/demanding more speed/performance from basically a slow, high-drag design, the 912 in the 80 HP configuration was offered. You can now install a turbo-charged R912 boasting 115 horses. The Vne hasn't changed. I would guess somebody will attempt to install a turboprop, maybe a PT-6, as soon as they figure out how to handle the engine weight.
The 701 will not outrun an RV. If you need speed you don't need a 701.
I'm not aware that Continental or Lycoming still builds the earlier engines you mention.....therefore parts, etc, aren't available everywhere. This may be a possible hinderance to current builders.
Engine speed: That's the choice of the designers. In order to insure that prop tips remain sub-sonic reduction arrangements are used. Some use internal gearing, some use external belts. Again, the desgn philosophy.
Recall that Riceburners (Japanese-made motorcycles) turn some really high RPMs and use a reduction arrangement.
They usually call this a transmission.
ADs: In the automotive world they're called "recalls". In the Cover-Your-Rear aviation world it is AD.
An AD is a fact of life; goes with the territory. An AD is part of the price of flying. Nobody likes this, but, like
the sunrise, it happens on a regular basis. Just get up early and crow at the dawn.....then go flying.
Some "hangar flying" involves myths......or the truth stretched a bit.
The Rotax 912 uses a "dry sump" arrangement for lubrication; somewhat akin to old radial engines.
Some years ago Rotax changed the oil tank dipstick to address an oil level issue. Markings on the new stick differed from the original to insure proper oil level. No problem.....except that somehow this dipstick-change story circulated enough times that it became a "Rotax 912 engines use a lot of oil" tale. Not true; oil consumption has nothing to do with the dipstick, but if you repeat a story enough times it takes on a mantle of "truth". ( Oh, if you fail to put the dipstick back in place then oil might blow out the hole. Now that IS oil consumpion! )
Putting strips of aluminum foil in the hubcaps on your car will foil radar speed traps. Now that's a truth!
There are thousands of Rotax-powered craft flying. Probably wouldn't be if there were a serious defect.
Likewise with other brands/makes of engines.
Sort of like buying ScotchBrite pads.......pay your money and take your chances; some are the wrong color.
If you have the opportunity to attend the Rotax factory-sponsored engine school it will be time well spent.
None of the above addressed your serious questions, but possibly it will bring out the flamethrowers.
Been too quiet lately.
Best Regards,
Zed/701/R912/90.xxx%/do not archive, again
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