Saturn Engine Mount?

Stuka Stunt Main Forum · 11 of 11 known posts recovered

StuntDuster · Dec 10, 2004 02:33 PM

I'm pretty new to building and I'm trying to learn as much as I can. I've never seen this type of engine mounting before. Is this new? Is this better than using maple motor mounts?
--Stephen

peabody · Dec 10, 2004 02:41 PM

#1 source

Steven...conceptually, the "soft mounts" are terrific, and Bob Hunt had limited success with them....

However, there turned out to be a whole bunch of issues with the system, and most that were built using the system eventually were converted to "hard mounts".

I believe that Bob's current plane uses maple motor mounts in a "conventional" manner?

The Saturn is a terrific airplane!

See Ya

Peabody

Bill Little · Dec 10, 2004 02:52 PM

#2 source

LAST EDITED ON Dec-10-04 AT 02:52 PM (CST)

Bob Hunt and Billy Werwage (first Geo XL) were both using those (Bob made them through his old CSC company) in the early '90s.
Problems with the shock "grommets" holding up.
No longer available AFAIK.
Bill <><

When the character of a man is not clear to you, look at his friends.
Japanese Proverb

Randy Powell · Dec 10, 2004 02:57 PM

#3 source

The Europa (a very similar plane by Bob's son, Robbie) shows both the soft mount and hard mount with layouts and templates for both.

Bill Little · Dec 10, 2004 03:03 PM

#4 source

BTW: I use the Maple Mounts in mine after talking to Bob about it.
I've had it for 8 years now, and it is a great flying ship.
Bill <><

When the character of a man is not clear to you, look at his friends.
Japanese Proverb

ferocious · Dec 10, 2004 08:23 PM

#5 source

the RC pattern folks have found that you need a snubber ring around the front bearing to keep the prop from whipping around. Also the snubber ring has to be very "soft" and the firewall rubber bushings can be pretty stiff(reduces power loss). See some of Dean Pappas' columns in FM the last few years. I think I got it right.

A properly done soft mount doesn't soak up much power and really does a number on airframe noise. The RC Pattern folks have to meet some very stringent noise limits.

Phil C

Brett Buck · Dec 10, 2004 10:28 PM

#7 source

>the RC pattern folks have found that you need a snubber ring
>around the front bearing to keep the prop from whipping
>around. Also the snubber ring has to be very "soft" and the
>firewall rubber bushings can be pretty stiff(reduces power
>loss). See some of Dean Pappas' columns in FM the last few
>years. I think I got it right.
>
>A properly done soft mount doesn't soak up much power and
>really does a number on airframe noise. The RC Pattern
>folks have to meet some very stringent noise limits.

The power-sucking aspects of the system are really not the problem. The real issue is inconsistency from run to run, and throughout the run. One of David's airplanes has a soft mount system, and it just *never* ran properly. Sometimes good, but usually all over the place. I think the problem is that all that stuff moving around just never settles into a steady vibration mode. It really doesn't move very far, but apparently enough. David had bad run after bad run, for months. Then he replaces the isolaters with aluminum standoffs the same size, and it *instantly* ran perfectly, and was very consistent. This is also what most other people found.

It was a nice try, but, no, forget it. Just build in regular beam mounts.

Brett

tomB · Dec 10, 2004 09:55 PM

#6 source

Then again, just beef up that firewall from 3/16" to 1/4", and use an RC fiberglass mount. You get stiffness and some shock absorbing at the same time. The fiberglass is tough enough to be threaded with self tapping screws, and you get perfect beam-to-beam alignment.

Tom B

Igor Burger · Dec 11, 2004 02:19 AM

#8 source

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EddyR · Dec 11, 2004 06:57 AM

#9 source

I think the one advantage was it made building the nose of the plane easyer if one wanted to taper the front.You would not need as many blocks and you would not be sanding through the plywood doublers. Bob always has very thin bodies on his planes. It worked best on small planes that had narrow noses.
Ed

ama21835 · Dec 11, 2004 07:18 AM

#10 source

I've never used the things, just theory.

CL planes fly around with high constant G-force, then pull a lot more g's manouvers. RC flys around at 1-G, and pulls only a little G in big loops. Conclusion, soft mounts pull more than design-G in CL.

A regular, rigid RC motor mount would give the same ease of constriction.