Removable cheek cowls on both sides should take care of the battery and electronic bits. 

I would look at the construction of Tom Hampshire's Kingfisher, as it features a 3/4" thick foam core composite profile fuselage.  I emailed you a PDF of the Stunt News article.

Never thought about using hardwood for the covering. Sounds strong.  At this time I'm a sport flyer, so legal thickness is not an issue.  My first electric powered profile Pathfinder was tail heavy even with a 4S battery.  It took about 1 1/2 oz. of nose weight to balance her out.  I'm more into hiding the electric components than anything else.  All those wires and circuit boards seem pretty ugly to me.   However, no smoke, no stink and no slime...

"Profile Mo-Best article"  Found it.  Just what I was looking for.  Thanks!!

Very nice.  I like profile C/L models, but all the electric components hanging on the side bugs me.  I have already built the nose similar to this.  My battery is on the inboard side and the ESC is outboard.  Love the wheel pants.  Unfortunately our field is grass.  This is a good thing as I haven't flown C/L in 40 years.  So far only one plowing session...    

Just some thoughts:

• The first big advantage to profiles are that they're easy to build and repair.
• If you compete, the second big advantage to profiles is that you can enter them in profile events.
• The two big disadvantages to profiles are that they're floppy in the back and can get heavy. (Full-fuse models can get heavy, too, but part of that is trying for a really impressive finish.

Having laid that out, let's think a bit:

• Tom Neighbur's "Hobo" design is as easy to build as a profile, but has a full fuselage.  His design technique could easily be extended to other, similar planes.
• You can build hollow-core profile fuselages, but then you have something that's as hard to build as a "Hobo" fuse, and as hard or harder to repair (Mike Haverly gave me a really nice Twister that was hollow-core with 1/32" ply sheeting.  It was rigid and not too heavy, and when I crashed it out of stupidity I ended up throwing it away because I couldn't figure out how to rebuild it without adding weight, adding ugliness, or taking longer than building a new plane)

So, maybe you really want to build a full fuselage plane, and just be casual about the finish?

Currently, I'm building profiles for my wife to learn to fly.  I'm using fairly light (8-pound) balsa for the fuselages.  This would be way too floppy for a normal plane, but I'm covering them with 1/4 ounce glass cloth.  The glass cloth stiffens them nicely without adding a lot of weight, and while I haven't had a rear-fuselage break with one yet, I anticipate that I'll be able to repair it fairly easily.  They're still a bit floppy -- but she's still learning.

Profile construction is a simple way to build a "small" model, maybe up to 40 size.  Beyond that, the box becomes better or maybe even necessary.

Is a hollow truss structure covered by hardwood really still a profile, even if it looks flat?   

If I ever build an over-40 stunter, I'll just use a box fuselage and leave to profile event to beginners.

I was thinking about routing a channel down the fuselage and gluing in a CF tube to stiffen it. They're so light, you can probably install 2, maybe 1/2" from the top and bottom of the fuselage.

Placing the comparable amount of carbon fiber on the outside of the fuse would do far more good to stiffness. The farther away from the center of the structure that the material is placed, the more affect it will have on stiffness..

The farther away from the center of the structure that the material is placed, the more affect it will have on stiffness..

Yup.  Hence a profile would have to be really heavy to be as stiff as a full fuselage.  Why does it need to be so stiff?  Some flexible profiles fly OK.  I have one that's just great.  

If flexibility is a problem, a way around it is to reduce aerodynamic moments (torques) on the fuselage and leave the structure wimpy.   There are three moments to consider: rolling, pitching, and yawing.  Pitching moment--bending the fuselage up and down--shouldn't be a problem.  A profile should be as stiff in this axis as a full fuselage, maybe even stiffer*.  Rolling moment is maybe the most significant.  I would make the side of the horizontal tail on the inside of the circle bigger than the outside side, because the pressure on the outside part is higher.  Just how much bigger I (or you) would have to cipher.  Then I'd check to see if it's balanced by taping a camera on the airplane.  I hadn't considered yawing moment until I saw a video taken by a camera looking aft on Mark Scarborough's profile Impact.  The tail deflected to the side quite a bit depending on whether the airplane was on the upwind or downwind side of the circle. A way around this would be to put wee carbon tubes running from the wing to the stab tip on each side.

*Hedging on the original post: No, it wouldn't.  I was only considering the fuselage sides.  A profile would still be pretty dad gum stiff in this axis.

DANG, I did not think of that, If I did that then Helmick would quit busting my chops about the flap root fairings on my profile being not legal for a profile,,


of course,, it only matters when I fly profile again,, right now I have my hands full trying to fly competative in expert,,

ok well, WHEN I get a replacement airframe built that is

So, your "flap root fairings" were added for a) Looks  b) Aerodynamics or c) Structural reinforcements to stop fuselage flex?  Clearly, NOT a) or b). Ended!

Profiles are by definition limiting. While others think Profiles suck, I think we should view them as a challenge to design and build a structure that fits the rules AND is stiff and light. I believe Larry Cunningham had a brilliant idea of curving the 1/64 plywood skins on his later Mo'Best variant, but I don't know if any were built that way, what the process was, or how well it worked out. I wish I could show the ciphering.  Steve

So, your "flap root fairings" were added for a) Looks  b) Aerodynamics or c) Structural reinforcements to stop fuselage flex?  Clearly, NOT a) or b). Ended!

Profiles are by definition limiting. While others think Profiles suck, I think we should view them as a challenge to design and build a structure that fits the rules AND is stiff and light. I believe Larry Cunningham had a brilliant idea of curving the 1/64 plywood skins on his later Mo'Best variant, but I don't know if any were built that way, what the process was, or how well it worked out. I wish I could show the ciphering.  Steve

hey Steve,,
its legal until someone protests it,, and wins the challenge,, that is someone who is flying profile,, so if you really are so against it, start flying in profile,, so whenever I bring it out to fly you can protest it. until then, it is legal,,,
I dont have any guilt  about it, I don't think its cheating, I think its legal, though perhaps on the edge

I must confess, my sense of humor about this is somewhat at its limit. Its Profile for gods sake,,
of course,, the fact that I am not currently flying profile kind of makes it hard for you to have your way.......

when I flew it no one else had a problem with it,,
bottom line, the fuse is less than 3/4" wide.... period
The area that is really more in question is profile electrics and how they dont meet the rule of lug to plug exposed motors,, are you going to go there too?
Besides that, whens the last time you saw me take a profile trophy home,, so does it really matter,,
enjoy it my friend,, build a profile and have fun ,,,

The area that is really more in question is profile electrics and how they dont meet the rule of lug to plug exposed motors,, are you going to go there too?

Someone needs to put JT up to clarifying the rules, there.  The spirit of the event (as I read it) is to keep everything easily accessible, and I'd want to see any electric motor mounting rule keep to that spirit, but I can't think of an equivalent to the "lug to plug" rule offhand.

Well, maybe "mounted such that the motor won't fly off of your plane and into a fellow competitor's wing", but Bruce Hunt doesn't frequent this forum so I probably shouldn't bring it up.

Someone needs to put JT up to clarifying the rules, there.  The spirit of the event (as I read it) is to keep everything easily accessible, and I'd want to see any electric motor mounting rule keep to that spirit, but I can't think of an equivalent to the "lug to plug" rule offhand.

Well, maybe "mounted such that the motor won't fly off of your plane and into a fellow competitor's wing", but Bruce Hunt doesn't frequent this forum so I probably shouldn't bring it up.

I really think its a mountain our of a mole hill thing.
There really hasnt been much to worry about, some discussion about Randy and his ringmaster delux could be had, my electrajet could be borderline, my impact profile could be borderline, I mean its PROFILE, lets keep it with the intent, SIMPLE and not create more rules to find loopholes in...

I really dont think there is a problem, even with my flap fairings/ Strakes, its still nothing like flying my built up planes. its a PROFILE it wont perform with a built up,, and I think thats really why its starting to bother me, Mine is not the only profile that could be regulated, but whats the point...

Has anyone considered building a profile fuselage with the body made from diagonal fixed wood. In other words with pieces cut at a 45 degree angle and put down right to left on one piece and left to right on the other. I did a profile using two 1/4 inch sides built that way and then covered with 1/2 oz F/G cloth with water based urethane as the adhesive. I could use it as a club if I needed to and it was light and had no twist at all.
More work but it does solve the problem.
I also built 3/ 60 sized profiles from Pat King designs and used the material supplied and then diagonally skinned to outside to make it 3/4 inch wide. These also will not twist under any load. These models were 2 at 900 square inches and one at 853 inch wing area. Surprisingly they are not hard pulling models in spite of their size.
Dennis

Dennis,
As a matter of fact "Back in the Day" (late 1950's to early 1960's) several of us in the Kansas City area flew Profile types for Combat and constructed the fuselages exactly as you suggested.  It does make them pretty stiff but obviously not lighter.  For the most part these airplanes were smallish light things with molded sheeting leading edges and flaps on the wing.  One of the best and most popular was something called a "Guided Muscle" (Yes that's "Muscle"), popularized by a fellow named Joe Ellsworth and Me!  Also several modified Flite Streaks were built that way.  The extra stiffness in the fuselage was instantly noticeable when it was flown.  The little airplane was competitive with most of the abbreviated "Wing" type airplanes like the "Quicker". Whatizit etc.  Also a number of I=Beam wing profiles were built with this type of construction and flew very well but exploded into a million pieces during a midair! 

At any rate the type of fuselage construction you suggested does successfully stiffen the fuselage and makes a better flying airplane but would get pretty heavy when scaled up for a large stunter.

My thought is that Larry's MoBest profile construction is just about Ideal for a profile stunt plane!  Excellent balance of stiffness and light weight.

Randy Cuberly

I know this is an old thread, but since I just this week did it to my Cardinal fuselage, I may as well show it.

I mentioned spruce early in the thread but I found some 1/16" x 7/16" CF flatbar and cut a slot for it, installed with epoxy. I won't waggle at all laterally. As for torsional twisting, I'll decide that when I get to it. Maybe I'll use 64th" sheeting, or more likely KISS and dope & tissue on the sides. As well as not being able to bend it sideways, the torsional twist seems stiffer than I had expected. It cost me 1/2 ounce.