The Murphy Builders Site

Last night I woke up in the middle of the night and realized I need to do something about my engine mount. Its a Murphy supplied mount for an O-540. Although it fit to the firewall, it was off at least 1/2 inch in both directions where it mounted to the engine. Consequently, we had to use bar clamps to get it on and now the Dynafocal mounts are warped beyond belief and the bolts are definitely not in the center of the holes. There is a lot of stress on the mount and the engine ears. The engine is a 1961 O-540 A1D5 rebuilt as an A4D5. The ears are the large 2 inch hole ears.

I have a note into Murphy tech support but haven't heard back yet. In searching the files, I noticed Neil Wischer had a mount from the factory that didn't fit either. He ended up having one custom built.

I would appreciate any advice here. It appears my options are to have one custom made, or perhaps cut into mine and splice it to the correct size. Thoughts? In any event, the current mount cannot remain on the airplane.

Thanks,
Jerry Folkerts

G'day Jerry !

I've made all my own mounts - so I'm probably a bit biased ......

But the mount SHOULD "be a perfect fit" - BOTH TO the firewall AND to the engine .... ( plus give the engine the correct amount off offset to the left or right of the thrust line needed re "P-factor" reaction from the engine choice ... ( SOME engines are offset to the left - whereas others go to the right - depending on their direction of rotation ) .... and thrust line re high wing vs low wing .... ( high wing engines installations often have down thrust - to offset the drag of the HIGH wing at higher power settings )

MOST Lycomings rotate clockwise as you sit IN the plane looking fwd ..... and they get offset to the right ... ( re the P-Factor reaction )
I set my mounts to have 4" of offset - as measured AT the finpost .... PLUS I also offset the vertical fin 3/4" as well - to help offset the same P-Factor ... and "R1" flew "hands off" - even before I fitted a GPS linked Wings Leveller ( poor man's auto-pilot )

I also set the engine to have downthrust as well ..... a few degrees from memory ...... ( I think Super Cubs have around 4 degrees ) - re the HIGH wing and THICK wing drag situation ...

I was easily able to DO all the above - as I bought my original 0-235 engine in pieces and rebuilt it myself .... so, while is WAS in pieces, I made up some blocks to hold a laser pen inside the crank tunnel ( in the crankcases ) - and then fired the laser through a hole in the firewall AT the tailpost - making thrustline measurements a piece of cake !

When I later fitted the sooped up IO-320 - I made up a bracket to hold the same laser pen at right angles to the engine flywheel and after eyeballing the PLANE with a hangar door across the taxiway - I then fired the laser at the same wall & measured the offsets that way ... and again, ... she flew "hands off" and was a delight to fly .... ( before I "met" the #%$!&%#$ bird at 130 knots ) .... :o(

I'm sure if you got "someone capable" ( a GOOD welder ) to modify your mount - it would be fine !


Hope this all helps !

Rick in Orrrrstraylya

Biggus and all
I believe I solved the problem this afternoon after a lot of research and careful observation. When I ordered the mount, I told the factory I had the large 2 inch holes and needed a Type II Dynafocal mount. Those are focused on the nose of the engine and were primarily used on Aztec's. I received a Type I mount. There is a 10 degree difference in the two and the rubbers are also a different thickness.
I posted a note on VAF and quickly someone wanted to swap out the engine ears. So, I have a smaller set of Type I's on the way. I'll have to purchase new Lord mounts but should be able to sell the others for a percentage of the original cost.
The problem should be solved, but should have not happened in the first place.
Best,
Jerry Folkerts

G'day Jerry ...

BEWDY !
( "Good" in Ozspeak ...


Rick in Orrrrrstraylya

My new engine ears arrived yesterday from a Harmon Rocket Builder. I installed them today with the new Lord mounts and it took one hour, by myself. Amazing when you have the correct parts how everything lines up! Now, back to work.
Best,
Jerry Folkerts

Hi Jerry,
I am at Sun and Fun and talked to the Murphy people. I was looking at the Radical and then realized that the Yukon was probably more in line with what we are interested in (flying on floats in Brazil). A little concerned because I haven't seen many (at the booth they said there was probably 120 flying). Any idea how many are actually flying? How close are you to getting in the air?

Thanks!
Matt

Matt,
Technically, there are only a couple of Yukon's flying. That said, they're most likely counting the Super Rebel as a Yukon, and that would be more accurate. The two airplanes are very close in structure etc. I should fly mid-summer. I'm finishing up firewall forward now, then will turn my attention to painting. It all takes longer than you expect.
The last couple of Super Rebels sold for mid 80s to lower 90s. They all advertise them much higher, but in reality, that's what they've been going for. It's a lengthy build, at least 3000 hours. That's basically two years if you're working full time. So it depends on when you want to get in the air. I doubt you could build one for less than 80 now, and probably closer to 100 and above. You might consider looking at a used one.
Jerry