Q1_Aircraft: HEXADYNE VS ULTRAVAIR

In looking for food for thought,I went back to the Hexadyne Engine
site to refamiliarize myself with it.
Seems like the Ultravair might be a better engine. A major plus to me
is that it is direct drive instead of reduction gear box like the
Hexatron. There are many Corvair 6 cylinder engines flying now and
have for many years.
I will try to make this look correct but it may mess up when I post it.

Ultravair Hexadyne
Bore 87.3mm 94.25mm
Stroke 74.7mm na
Displacement 959.64cc 800cc
Horsepower 35 @ 3500rpm 60 @ 5750 Cruise 45hp
Weight 80 lbs 98 lbs
Width 27.5' 23.5'

Seems to me that 94mm cylinders can be added to the Ultravair and it
may produce the same power or near same as Hexadyne, but at a lower
rpm and definitely a lower price. It will probably weigh less also.
The big plus to me for the Ultravair would be the direct drive. The
above numbers are correct only if I did my calculating correctly. I
was guessing on the number of centimeters per inch. I was too lazy to
check and see if it was correct. I used 2.6 cm per inch and 17.57 ccm
per cubic inch.
Anyone feel free to correct me please.
Larry H.

As for the cylinders, check out Mark Langfords KR2S webpage with a full
Corvair of 135hp.

using (among other things) the 94 mm cylinders. Some machine work is
required but the 94mm cyls save appx a pound each over the stock Corvair
cylinders.
Marks engine is a work of art. The guys who created the Ultra vair have
done it as cheaply
as possible. To me this speeks volumes. I have no doubt the Hex engine will
wrk fine ... and I am in no way trying to discredit the choice; I just find
the 1/3 Corvair to be dirt simple
with a reasonable direct drive power output.

To each his own. One thing for sure, If you buy an engine, you dont have
all the developmet work to do to get it into the air, therefor you realy only
have one thing left to flight test ... and that is the airframe.

Eithe way a break in plan for the engine will be needed with either choice.

As David likes to say 'your mileage may vary'

Gene

In a message dated 2/18/2005 11:20:46 PM Central Standard Time,
laheze@... writes:
Seems to me that 94mm cylinders can be added to the Ultravair and it
may produce the same power or near same as Hexadyne, but at a lower
rpm and definitely a lower price.


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