Blake, I thought  you might be interested in seeing a process photo
or two. This is the engine mount I am currently working on. The pictures
were taken this morning after disconnecting it from the fixture. It is
just tack welded.  I am particularly pleased with the high quality of
fit ups done  by Joy.  All I did was the  welding.  This mount will be
ready to ship in another week.

 It is colder than hell and the temps are falling. Wind is blowing.
Three inches of slush now frozen as hard as granite.  We need to go to
town but getting out of the driveway may be impossible.    California
dreamin....     Jerry


Need I say I told you so? :)

Joy is Jerry's wife and she has a talent for fitting steel tubes in
clusters.

Paul Lamar

Jerry and Paul:  r.e. the RV-4 mount...
1. Tube material specs and diameter/wall thicknesses
2. When finished can you advise r.e. weight?
2. Does Jerry's wife Joy who fabricated the clusters have an unmarried
sister?

Steve Beckham.

I usually use 3/4" OD .049" wall for the top tension tubes and 7/8" OD .049"
wall or 1 inch OD .049" wall for the long lower tubes in compression.
We use 6 G's as the design criteria to cover an airplane dropped in from
ten feet :) Aerobatic airplanes I would go up on the wall thickness to
.065" and use 10 G's.


http://www.rotaryeng.net/motor.html

Actually I can give you exact paper patterns for the cut ends of tubes
using an un-wrap feature in Rhino :)

I can tell you the weights as Rhino also has that volume calculation
function but each part must be tallied up. Steel is .3 pounds per
cubic inch.

These mounts are less than about 10 pounds as I recall. Jerry can
answer that question better than I. Dozens have been built for all types of
aircraft. They are  all similar in their design philosophy based on
the Questair Venture design by Jim Griswold. The basic idea is use two large
rubber bushing located on either side of the CG for engine, gearbox and prop.
These industrial bushings cost about $7 each as opposed to up to $100 each
for Lycoming type rubber bushings.

Paul Lamar

Thanks guys.    The RV 3/4/6 mounts incorporate the gear leg tube sockets
and that skews the weight somewhat when compared to other non-Wittman
configured mounts, so that is why I asked the question about weight ready to
install. Jerry before you install the engine can you let us know weight?
Paul, are there any RV-3 or 4 drivers yet flying with this mount?

Steve Beckham

Yes it does. The mounts with the gear leg sockets may be heavier than 10 pounds.
I am not sure about RV4's flying with this type of mount.
Jerry would know if he has delivered any RV4 mounts yet. The Tailwind
also has a similar mount. We have several other airplanes flying with this type of mount and of course there are several Questair Venture airplanes flying.
There may be an RV6 or RV7 tail dragger mounts out there with gear leg sockets.
Jerry built a few variations on this mount with different rear mount
configurations. Minor modifications to the idea. RV4's have fallen out of favor in the last 5 years or so. Van has moved away from those types of main gears.

Paul Lamar