Full Fuse to Profile

[Motorman]

You guys that have taken a full fuselage design and turned it into a profile, did you find that it tends to come out tail heavy?

Thanks,
MM

[Dan McEntee]

   I would figure that you would find that obvious. There has been volumes written here on built up profile fuselages to help avoid that condition, not to mention the numerous discussions on building full fuselage anyway because it was lighter and less prone to twisting and flexing. The only real reason for a solid plank profile is for simplicity and speed of construction.
  Type at you later,
   Dan McEntee

[Dan McEntee]

   And the following post should prove it is not a new concept. It really pays to read everything, maybe spend less time on the computer!

   http://stunthanger.com/smf/building-techniques/nothing-new-in-c

    Type at you later,
    Dan

[Glenn (Gravitywell) Reach]

The answer to your question is "Yes!".  I have done it twice (both times with solid fuselages) and both times the model needed an ounce or two in the nose.  It may be different with a built up, profile, but I don't know for sure, I did mine before I knew about them.  Hope this helps.

[Motorman]

What's the max width allowed in profile stunt for a 40 sized plane?

Thanks,
MM

[Randy Cuberly]

What's the max width allowed in profile stunt for a 40 sized plane?

Thanks,
MM

Generally, I think it's considered to be 3/4 inch.  However since Profile Stunt is not an official event it may vary according to areas or regions.

Not entirely sure there are "official Rules".

Randy Cuberly

[Steve Helmick]

Here in the PNW, it's 3/4" maximum, meaning no + tolerance. There should be a go-no go gauge. I'll endeavor to come up with one for next year.  Steve

[Glenn (Gravitywell) Reach]

One would have to be careful about designing the thickness of the fuselage to allow for covering and finish.

[Motorman]

Where do they measure that 3/4"? If I make it 5/8" then add two 1/8" plywood doublers to the nose that puts me at 7/8" but still 5/8" behind the wing, still legal?

Thanks,
MM

[Brent Williams]

Use a foam core on the aft section to save weight.
5/8 foam core with 1/16 balsa sides to yield a 3/4" slab.

[Fred Underwood]

Weigh the foam and then weigh the balsa needed to triangulate, then the adhesive to laminate versus to glue the balsa pieces to triangulate.  If you look at say 6 lb density balsa for triangulation and 1 lb foam, even visually the balsa doesn't take up 1/6 of the area.  Foam is heavier when I tried it.

Crist Rigotti has some good ideas and weights here.

http://stunthanger.com/smf/gettin-all-amp'ed-up!/2013-electric-stunter-a-build-log/

I did similar and narrowed the center structure to allow for balsa skin over the 1/64 ply, for easy use of Monokote.  The structure is adequate for a 680 sq in profile. 

Mike Haverly also mentioned carbon strips, and no plywood, and has a large size profile.

http://stunthanger.com/smf/building-techniques/profile-fuselage-reinforcing-questions/ 

[Steve Helmick]

Where do they measure that 3/4"? If I make it 5/8" then add two 1/8" plywood doublers to the nose that puts me at 7/8" but still 5/8" behind the wing, still legal?

Thanks,
MM

Our NW Profile rule says 3/4" maximum at the wing/flap TE. You can look up the rules on www.FlyingLines.org However, as noted, that's our rules, and your local rules may very well be different. Best plot is to ask the local CD's or clubs that sponsor the contests you attend. It's not standard, because the rules are neither PAMPA nor AMA regulated. Hopefully, that will change eventually, after the bugs are worked out and folks decide what works best.  Steve

[Tim Wescott]

Our NW Profile rule says 3/4" maximum at the wing/flap TE. You can look up the rules on www.FlyingLines.org However, as noted, that's our rules, and your local rules may very well be different. Best plot is to ask the local CD's or clubs that sponsor the contests you attend. It's not standard, because the rules are neither PAMPA nor AMA regulated. Hopefully, that will change eventually, after the bugs are worked out and folks decide what works best.  Steve

My understanding is that in areas of the country influenced by the Sig event, the maximum width is 1/2".  So -- it depends on what prevails in your area.

I think the AMA does have a definition of what constitutes a profile, and I think that's what the NW rules use -- but, if you don't live where the NW rules prevail, find out what prevails in your own region.

I aim for 5/8" or 11/16" thick in the bare wood, so that I don't have to sweat not fitting inside of Steve's precision-ground, stainless-steel, NIST-certified no-go gauge.

[Russell Shaffer]

I figure that balsa is soft so the no go gage will shove right over it.  I still want to know if a Fierce Arrow with the cowl off is legal.  It is less than 3/4 behind the TE.  What say you, Steve?

[Steve Helmick]

I'd say "I didn't write the rules." Bite me, Russell!  Steve

PS: You too, Tim. Hey, I got that Camellia lumber you wanted. It's still sorta round. Should I mail it, or will you pick it up?   

[Mark Scarborough]

I'd say "I didn't write the rules." Bite me, Russell!  Steve

PS: You too, Tim. Hey, I got that Camellia lumber you wanted. It's still sorta round. Should I mail it, or will you pick it up?   

Steve, some clarification will be needed, how deep is the no go gauge,, just sayin

[Motorman]

So, in converting full fuselage to profile I've found there's allot of wood in the lower nose due to the outline of the inverted engine cowling. Should I just copy the outline to replicate the full fuselage look or come up with a form follows function type outline with less side area.

MM 

[Brent Williams]

So, in converting full fuselage to profile I've found there's allot of wood in the lower nose due to the outline of the inverted engine cowling. Should I just copy the outline to replicate the full fuselage look or come up with a form follows function type outline with less side area.

MM 

Dan Rutherford wrote extensively on these topics in his epic tomes for his downsized profile Impact (Wimpact).  Search "wimpact" here and over at stuka and I think a lot of your questions will have been covered.  It's full of good info.