Fuse stand load bearing area

rjcthree · #1 06-13-2010, 06:52 PM

I'm about to hang my engine. The fuse is supported on a stand that is under the wing spar box. It's 5.5" wide, so it hits both the front and back of the main spar box, and it runs the full width of the fuse. It is covered with white insulation foam, the really soft stuff, which if memory serves, has about a 7psi crush strength (blue foam having ~15psi).

I figure there's going to be roughly 600 lbs, with fuse, panel, engine, prop, cowl . . .you get the idea. Add me and tools it gets to 800. The foam will take the load(with something like 200 sq in of bearing area), but I'd really not want to bend skin the spar box area. The foam will distribute some of the load.

Anybody done anything similar or have thoughts?

Rick 90432

Mike S · #2 06-13-2010, 07:34 PM

Be sure the weight of the engine doesnt shift the C/G forward of the spars------I am figuring the tail is not attached.

Why are you doing this now, instead of after getting it on the gear???

Seems it will be harder to mount the gear with the engine on it.

flion · #3 06-13-2010, 09:43 PM

I'm with Mike on this. The newer RV -xA models can be on the gear even without the wings, thanks to the newer spar design. All the taildraggers can/should have the mains on when the engine mount goes on.

If you are still working inside the fuselage and want to keep it low for accessibility but want to get the engine in place to route systems through the firewall, do it temporarily by leaving the engine on the hoist and pinning it roughly in place with a couple of bolts. That'll be good enough for planning your routing and you can quickly get the engine out of the way to work on the firewall. Then later, when you are finished inside the cockpit and have the aircraft on its gear, you can install the engine permanently and take it off the hoist.

rjcthree · #4 06-14-2010, 06:12 AM

I'm mounting the engine with the fuse on the stand to keep it low. I thought about getting it on the gear, but didn't see any positives in that. Counterweight is installed at the tail.
I've already gotten about 75% of the FW stuff mounted - it's just hoses and wire routing from here - all the holes **should** be drilled.

For the purposes of thinking further - what is the wheel track width(will I kill myslef trying to move around my single-car+ garage shop), and what is the bottom fuse height gear on?

Rick

flion · #5 06-14-2010, 07:32 AM

The positives are that the gear are meant to support the weight, unlike the skins. There's no real reason to keep it low. If you're worried about the weight of the engine nosing it over, keep the hoist attached until you've got the tail together. Better still, hang the engine last.

Vlad · #6 06-14-2010, 07:41 AM

Quote:

Originally Posted by rjcthree

For the purposes of thinking further - what is the wheel track width(will I kill myslef trying to move around my single-car+ garage shop), and what is the bottom fuse height gear on?

Rick

Wheel track 82" full width clearance from axle cap to cap 88" bottom fuse height on RV9A is appr 28". All measurement are with engine mounted.

Lars · #7 06-14-2010, 10:45 AM

I put my -7 on the gear when I hung the engine. I'm 6 feet tall and I find that I actually prefer the extra height. My thrashed lower back thanks me for not having to stoop so much to work on the engine installation. I'm not working in a garage, but the corner of the tee hangar into which my fuselage is stuffed might as well be a one car garage, considering the width. I haven't found it to be a problem working around the gear, or for that matter the propeller. Another upside, purely psychological, is that it looks so cool to see it on the gear after years of seeing it on a stand!