Fuse Weight

[Murray Randall]

Attached are a couple of pics of a trial weighin of my cabin mod.  Whats in the pics needs wings, wing struts. cover, prop and motor.  The weight of everything in the pics is 75 lbs.  I'm allocating a final weight of 100 lbs for the half VW that weighs 80 lb as it sits on the bench. Figuring 100 lbs motor there is 79 lbs left to make 254 lb.  Thats cutting it awful tight eh?  I weigh 155 lb and was shooting for a 500 lb gross. Doesn't that sound doable if not the 254? The pic shows the .060 cold bent windshield, sky light and fiberglass centersection leading edge that includes a lips for the windshield top attach and the skylight fwd attach.  The windshield has a couple of 1/8" fiberglass rods off the cabanes for a center reinforcement socketed into a nylon seat.  The seat belt shoulder strap is still center mounted but I listened and fully expect to change to a cluster attachment. But I still prefer the push to release clasp, for reduced weight, rather than the prefered pull latch aircraft clasp.  I appreciate the advise with the belt installation.  If I knew the weight of the high class multi point harnesses that everbody is using, I'd consider that, but the system that I made is wicked light. UPS says that 24 yds of peel ply will arrive Thur.  And again I appreciate everyones advice on fabric also. Thank you

[Steve]

I Like It ! ! !

Here are some LE's weight's and reflections there-on:

http://www.angoraaffaire.com/leu/whatdoesitweigh_.htm

[rockiedog2]

man thats gonna be a cool plane
i really like the properly trashed shop too

[Sam Buchanan]

Attached are a couple of pics of a trial weighin of my cabin mod.  

Murry, does your engine mount have a diagonal to eliminate lateral movement? Maybe I can't see it in the photo....

Another observation, and my confusion may be due to the angle of the photo (and my lack of formal engineering background) but do the diagonals connecting station 1 to station 2 terminate at midspan of the forward cabane instead of a cluster? If so, the load path is being transferred to an unsupported area of the cabane. But maybe I can't see all the bracing.

The forward cabane is most likely the most heavily stressed area of the airframe.

[Murray Randall]

Your right Sam, there is no lateral diagonal in the engine mount. I tried and tried but couldn't get a tube between the mag and the starter. No way. Vertical diags but no lateral. My bum legs don't want me stumbeling around out front so I probably will keep the starter.
The diagonal into station 2 on the left side is mid span, no cluster as you politely point out Sam. On the right side the comparable diagonal clusters with a square tube conventionally. As you say the station 2 verticals are working pretty hard. But I did a finite element analysis a year ago with many revisions to the cabane and verticals. As I see it the four longeron design with the cabanes and diagonals used, works because the X bracing in the center section helps the cabanes carry the asymetiric wing drag loads. The X up there is important, it didn't work with one diagonal leg of the X. It needed the whole X. None of this is of interest to straight plans builders. Stick to the drawings. While doing my computer thing, I did a finite element analysis of the XL and everything rang out just fine up front there.

[Sam Buchanan]

Your right Sam, there is no lateral diagonal in the engine mount. I tried and tried but couldn't get a tube between the mag and the starter. No way. Vertical diags but no lateral. My bum legs don't want me stumbeling around out front so I probably will keep the starter.
The diagonal into station 2 on the left side is mid span, no cluster as you politely point out Sam. On the right side the comparable diagonal clusters with a square tube conventionally. As you say the station 2 verticals are working pretty hard. But I did a finite element analysis a year ago with many revisions to the cabane and verticals. As I see it the four longeron design with the cabanes and diagonals used, works because the X bracing in the center section helps the cabanes carry the asymetiric wing drag loads. The X up there is important, it didn't work with one diagonal leg of the X. It needed the whole X. None of this is of interest to straight plans builders. Stick to the drawings. While doing my computer thing, I did a finite element analysis of the XL and everything rang out just fine up front there.

Murray, I wonder about the impact of eliminating the tubes that tie the XL station 1 to the top longeron. This leaves the nose of the fuse with the full weight of the engine cantilevered with no direct connection with the cluster at the top of the forward cabane. Of course some aircraft do this, but this removes a major source of rigidity of the very light Eagle fuse. The reason the Eagles can be built out of light material is because of the strict use of triangulation in the design. Eliminate some of the geometry and tube sizes need to be increased to maintain rigidity. Now weight creep sets in.... all this takes me into an area far beyond my shadetree engineering abilities.  

Also noticed the left side of the seat is anchored mid-span instead of a cluster. Landing loads can put a huge strain on that attachment, hope the tube doesn't bend.....

I'm afraid you are setting yourself up for a cracked engine mount. The 1/2 VW has a powerful rocking couple that will put some big lateral stress on the mount. With nothing to damp the lateral flexing, something will give. Take a look at conventional engine mounts, they all have diagonals to insure rigidity regardless of how the engine shakes, or to accommodate prop gyroscopic forces.

Please keep in mind I'm not trying to discourage your efforts, just pointing out some things I hope don't develop into problems. I know you trust the computer analysis, but changing traditional engineering practices puts you out there on the fringes of the envelope.

Man....you are definitely going experimental on us........hope you don't mind being a test pilot. Stay safe!