Buying prop strike engine

If your going to rebuild anyway, take a look at these.
http://www.airboattrader.com/PartsForSale.htm
Lou

Great site, I especially like the 8 cylinder Contential:

http://www.airboattrader.com/PartsF1420.jpg



"Lou" wrote in message
ups.com...
If your going to rebuild anyway, take a look at these.
http://www.airboattrader.com/PartsForSale.htm
Lou

Lou wrote:
If your going to rebuild anyway, take a look at these.
http://www.airboattrader.com/PartsForSale.htm


OK, if you're not going to buy a certiifed engine, then
what are the pros and cons of buying an airboat
engine vs a VW or Corvair conversion?

--

FF

wrote:
Lou wrote:
If your going to rebuild anyway, take a look at these.
http://www.airboattrader.com/PartsForSale.htm


OK, if you're not going to buy a certiifed engine, then
what are the pros and cons of buying an airboat
engine vs a VW or Corvair conversion?


One, the airboaters are getting rid of the LyCon aircraft engines in
droves. That should tell you something.

Two, VWs are too small to be used as a direct drive airboat plant. A
direct drive VW is good only for motorgliders, drones, and the very
minimal single seat aircraft. Geared (or belted) VWs might be okay but
none are ever seen. Corvairs are proving crank breakers when operated
(direct drive) at power levels much over that of the old Pietenpol
conversions.

In my opinion there are only two ways to fly unless you have warbird
money: a certified aircraft engine in a certified airframe or a
homebuilt with an en-bloc-construction, liquid cooled general purpose
engine with belt or gear reduction. VWs, two strokes and the like are
just not powerful or dependable enough, noncertified "aircraft" designs
like the Jabiru are a worst of both worlds and vastly overpriced scam,
and LyCon aircraft engines are overpriced museum pieces if you don't
need a certificated engine.

Bret Ludwig wrote:
wrote:
Lou wrote:
If your going to rebuild anyway, take a look at these.
http://www.airboattrader.com/PartsForSale.htm


OK, if you're not going to buy a certiifed engine, then
what are the pros and cons of buying an airboat
engine vs a VW or Corvair conversion?


One, the airboaters are getting rid of the LyCon aircraft engines in
droves. That should tell you something.

Two, VWs are too small to be used as a direct drive airboat plant. A
direct drive VW is good only for motorgliders, drones, and the very
minimal single seat aircraft. Geared (or belted) VWs might be okay but
none are ever seen. Corvairs are proving crank breakers when operated
(direct drive) at power levels much over that of the old Pietenpol
conversions.

The stock VW cranks break too. 'Conversion' implies modification
which, at a minimum for VW and Corvair engines would include
replacing the crank. That doesn't address any other problems.


In my opinion there are only two ways to fly unless you have warbird
money: a certified aircraft engine in a certified airframe or a
homebuilt with an en-bloc-construction, liquid cooled general purpose
engine with belt or gear reduction. VWs, two strokes and the like are
just not powerful or dependable enough, noncertified "aircraft" designs
like the Jabiru are a worst of both worlds and vastly overpriced scam,
and LyCon aircraft engines are overpriced museum pieces if you don't
need a certificated engine.

Intersting, are there many en-bloc-construction, liquid cooled
general purpose engine powered homebuilts flying? (Aircampers
for one, right?).

--

FF

Runout is not a reliable indicator of damage. The prop may have
struck the surface more than once and bent the flange back from the
worse position it had been bent to on the first contact. Any bending
can crack a crank and the flange will dial OK; I've seen it on a couple
of O-200s we used to operate. I had an A-65 crank break in flight
between the first and second journals (rearmost and next ahead, the
farthest position from the prop) and I have read that these engines
tend to break at that spot after a prop strike. Flange runout, of
course, would have indicated nothing about the other end of the crank.
A propstrike also twists the whole crank (inertia) and cracks can
develop at the journal fillets; seen that, too. Runout readings won't
tell you everything about twist. The rest of the components, like rods,
pistons and gears, get shocked and will often show cracks or
deformation. Lycoming has an AD requiring teardown after any sudden
reduction in RPM, including contact with "grass, water or similar
yielding medium." Seems that the bolt that retains the crank gear on
its rear end comes loose and eventually the gear falls off. In flight,
of course. The camshaft and everything else stops turning.

Dan

Corvairs are proving crank breakers when operated
(direct drive) at power levels much over that of the old Pietenpol
conversions.

Flat out misleading, and shows that good 'ole Brett did not take the time to
read the whole story from William Wynne.

There are many factors that contribute to the Corvair crank breaks, but a
couple are using too long of a crank extension, using too heavy of a prop,
and using small props turning too many RPM's on very fast, slick aircraft.

If a person is really to want the whole, truthful story, it would be wise to
go to William's site, and read the whole story for yourself. Don't take
someone else's word on it, and especially not Brett's.

Sorry I had to respond to you, fredfighter, but I couldn't let that pass,
and I have Brett in the round file, where he belongs.
--
Jim in NC

Morgans wrote:
Corvairs are proving crank breakers when operated
(direct drive) at power levels much over that of the old Pietenpol
conversions.

Flat out misleading, and shows that good 'ole Brett did not take the time to
read the whole story from William Wynne.

There are many factors that contribute to the Corvair crank breaks, but a
couple are using too long of a crank extension, using too heavy of a prop,
and using small props turning too many RPM's on very fast, slick aircraft.

If a person is really to want the whole, truthful story, it would be wise to
go to William's site, and read the whole story for yourself. Don't take
someone else's word on it, and especially not Brett's.


I don't claim to be an authority on corvairs or on any other engine. I
suggest that the authority on general purpose engines is their
designers and therefore one should endeavor to restrict all loads on
them to their design application. The marine guys, particularly
Kiekhafer with their I/O drives, should be studied long and hard.

Notice if you have a prop strike on a marine engine you don't
dismantle the engine. Why not? The drive takes those loads. Emulate
that.