103mm -vs- 105mm P/C

[Joseph]

Tom,
On that aircraft conversion, did the jackshaft take the power from the #1 or #4
end of the crank? We did a conversion with
the engine in reverse with the Gilmer drive
off #1 main and swung a 6 foot fixed prop
from the jackshaft above. The guy wanted a
1:1.7 redux. We never saw the aircraft. I
always wondered if it had been done before.
Another non-colorful Type 4 aircraft application: A DTM Type 4 running a pump at a constant 3,000RPM driving a Urea (fertilizer)
spreader. The engine, spreader and 2 ton
container are suspended by cable below a
Bell Helicopter and used to service tree farms. That engine is serviced only by A&P
mechanics.
Not all Type 4's are Kafer racers...
Joe
Oregon Performance Products http://www.spiretech.com/~opshroud

[Tom Notch]

uhhhhhhh, let me try and remember some of the details. The drive came off the flywheel end with the flywheel cut down to a ring gear and something to bolt the sprocket to. The #1 thrust is a heck of a lot more robust than the #4, which was his very logical reasoning. A jack shaft consisting of a modified T1 swing axle tube assembly ran over the top of the engine with the prop attached to the shaft. Don't really remember quite what the axle tube mods and shaft were except that there was bearing at both ends. Seems to me the engine still had the bosch FI on it.

The flywheel was to the firewall behind it so I guess you could say the engine was turned around.

Hey, my Notch won't be a racer. More along the lines of a touring car of the late 50s to mid 60s era. But it will pull at any speed when ya roll into the throttle!

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Tom Notch

[JW63]

Tom, Joe and group: I don't think Bob Hoover ever posts here(?). But any of these VW-kit-plane questions are perfect for him. He's probably the greatest dual-authority on VW's and aviation on the planet. Somebody should cross-post to RAMVA or one of the other NG's (VW-trikes?; buses?)that Mr. Hoover frequents. Just my $.02, guys. Later.

[Joseph]

JW63,
Bob hoover does have an experimental aircraft
mechanics license (pretty rare), but Bob
has'nt been posting much as of late on RAMVA
except for his great Christmas story.
Joe
Oregon Performance Products http://www.spiretch.com/~opshroud

[Tom Notch]

Neat aircraft stuff! I have a friend somewhere down in SoCal that has a brother that did a T4 conversion to aircraft. He used a jack shaft and cogged belt for speed reduction of the prop. This got the engine up into its power curve. Maybe some might know him here, Ivan Anderson, nice Swedish fellow.

Its been at least 15 years since I saw the conversion and I think it was a Bellanca (or Mooney?). His thoughts were to get the power curve right and eliminate possible thrust bearing trouble. It was not set up with redundant ignition when I last saw it, heck, no wings either! But he was doing taxi tests last time I spoke with him years ago.

The rods out of a T4 would be one of the very last parts that would need replacing do to strength concerns, they are incredible over-built. That will work to your favor on a 78 stroke crank, the short rod helps bring the power curve down or widens it, depends on your viewpoint.

A stroker T1 94mm piston and a 78 crank could be a pretty nice engine with a lot of torque for spinning the prop. What's the max rpm for the prop size you will be spinning? I know you have a limit on that below the tips going sonic. The aircraft I deal with are Boeing jets. This is a cool "conversion" topic!

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Tom Notch

[JW63]

The stock crank and rods on these engines is bomb-proof with any P&C combination. You might also think about advancing a stock cam 4-6 degrees to move the torque peak lower if you are going with direct drive. Isn't the Sonex a beautiful aircraft?