Profiles vs Built up fuselages

[Jerry Leuty]

    I am curious. I have been at this hobby a long time now. I have flown lots of different type of C/L planes. Most claim that one will never get any good at the stunt pattern flying profiles. Aside from the aesthetic appearance of a model can you really tell the difference in flying the two? I have been told by some that they would never fly a profile and that profiles are called 'beaters' for what ever reason. I will continue to build both types. But the question is; Are you really a good enough pilot to tell the difference, if there is any, in the two models? If so what are those differences?

Jerry

[Garf]

I fly mostly profiles, mostly because of the trouble with starting some engines inverted. I have one engine that starts easily inverted and I have that on an ARF Nobler. It is the best flying combo I currently have.

[Scott B. Riese]

Lots of people will chime in on this question.

YES the Full Fuse plane IS aerodynamically better. You can build the Full Fuse lighter and stronger. There are some that feel that this is not so, and you tell them over and over you need to build a Full Fuselage to understand to difference.

I did and what a difference! For Sport Flying...Profile is the way to go.

[Garf]

How about a built up profile?

[Jerry Leuty]

        I like the appearance of built up fuselages and they are stronger. But the profiles offer so much more accessibility than the other. I went to my local Home Depot and bought a 4'X8'X5/8" sheet of the pink foam board. It has a thin plastic sheeting that you peel off either side. Mark your profile out line with a thin marker or pen, cut it out on a band saw or jig saw. Add your wood beam motor mounts..........be sure they are about 9" long. Add some stiffeners above and below where the leading edge of the wing is. You can use Popsicle sticks or 1/8" plywood. The Popsicle sticks are available at Hobby Lobby. Sheet the engine area with 1/16" ply and go back to mid way in the wing area. Then sheet the aft section with 1/16" stiff balsa. Oh I outline the circumference of the fuselage with 1/8" balsa stripes. Sand it all down and you will have a fairly light, and straight profile. This stuff is about $10 a sheet so you can use lots of it in experimenting. I have even cut out some ribs and built a wing for a Oriental. Just the ribs are foam, every thing else is the same as a balsa rib wing. So far so good.

Jerry

[Dick Pacini]

        I like the appearance of built up fuselages and they are stronger. But the profiles offer so much more accessibility than the other. I went to my local Home Depot and bought a 4'X8'X5/8" sheet of the pink foam board. It has a thin plastic sheeting that you peel off either side. Mark your profile out line with a thin marker or pen, cut it out on a band saw or jig saw. Add your wood beam motor mounts..........be sure they are about 9" long. Add some stiffeners above and below where the leading edge of the wing is. You can use Popsicle sticks or 1/8" plywood. The Popsicle sticks are available at Hobby Lobby. Sheet the engine area with 1/16" ply and go back to mid way in the wing area. Then sheet the aft section with 1/16" stiff balsa. Oh I outline the circumference of the fuselage with 1/8" balsa stripes. Sand it all down and you will have a fairly light, and straight profile. This stuff is about $10 a sheet so you can use lots of it in experimenting. I have even cut out some ribs and built a wing for a Oriental. Just the ribs are foam, every thing else is the same as a balsa rib wing. So far so good.

Jerry

That is an incredible "thinking outside the fuselage" idea.  Do you have any pix of planes built that way?

[Kim Doherty]

One day some twenty or so years a go I had a twister profile that had been trimmed to the point of perfection and had been flown for more flights than I can count. A Chinese guy asked if he could fly my model because his was not put together or something. I allowed him to fly the plane and watched in awe as he flew a pattern so clean and sharp you would think you had died and gone to heaven. I later got to see him fly a few more patterns and they all looked like the one with the twister.

Model airplanes are basically stupid. They do not know how thick the fuselage they are held together with is. It is irrelevant how thick, how straight, what it is made from, or what it looks like. If it (the fuselage) is stiff and holds all of the parts in proper alignment with some respect for side area and wind resistance it will perform EXACTLY THE SAME as any other similarly equipped model.

Anyone who says that JUST by moving up to a built up fuselage made them a significantly better pilot is kidding themselves. For most, success comes at the bottom of gazillions of gallons of fuel over a long period of time. Talent is a very depressing thing if you do not have it. If you want to improve keep the profile, trim it relentlessly, watch really good flyers, listen, practice, build the same model two or three times until you know it's every nuance. Get some coaching, listen, practice, watch some really good flyers.........

If success is measured by flight scores, success will not come in the main as the result of moving the sides of the fuse further apart.

Kim.

[Larry Cunningham]

I think the standard assumption about profiles not flying so well has a lot to do with the classic nose construction, using such materials as Lite Ply doublers and (short) basswood engine mounts. This leads to problems with vibration, particularly with older motors, which precludes a decent "stunt run".

Another problem with many profiles is torsional rigidity, particularly affecting the stabilizer. In spite of this, I've seen many profiles with crooked, twisty elevators which flew quite well.

The other thing I will say and be prepared to be disputed is that a profile fuselage, using classical sheet construction, is difficult to built light and adequately strong.  Using that "punky" super soft wood, in addition to seeming quite wasteful (to me), results in a fuselage which is not very strong. The same amount of balsa mass can almost always construct a built up fuselage using wood that is not so punky (and porportionally stronger by weight). The monocoque features of a full fuselage  will definitely make it more rigid.

Nowadays we frequently "build up" our profile fuselages, and use such things as 1/64" plywood sheet planking to make them rigid. This, combined with an improved nose construction and modern engine can produce a sweet flying profile model.

Still, I submit that a profile can NEVER compete with a built up fuselage for appearance. With the exception of items like cowls, cockpits, and canopies, it's not a lot more work to construct a built up.

Oh, one more thing, I think most would agree that the typical profile fuselage is aerodynamically "dirtier" and therefore has more drag than its equivalent built up version. I certainly believe it, but considering the way we trim our stunt models (excess of lift, thrust and drag and light weight), a sleek fuselage may not be necessarily optimum or at least is not a detriment.

L.

"Aibohphobia: the fear of palindromes." 

[Kim Mortimore]

The popsicle stick-type internal stiffeners Jerry mentioned can also be used successfully with conventional balsa profile fuselages--both in the area of the leading edge as Jerry said, and in the area of the trailing edge, where most profile fuselages are the weakest.  The sticks provide a lot of "bang for the buck" in terms of stiffness vs weight, since the wide dimension of the stick is installed horizontally, along the yaw axis, the profile's weak axis, as opposed to doublers, where the wide dimension is installed vertically, requiring extra thickness or heavier material, and thus a lot of weight for the gain in yaw-axis stiffness.  An internal stiffener(s) combined with relatively thin doublers creates a sort of "captive" I-beam that is very stiff.  A wide Buster-type cheek cowl also capitalizes on width to increase nose stiffness with only a small increase in weight.

Another weight-effective technique is to sand some curvature into the vertical sides of the profile, and then fiberglass or sheet the curves, producing monocoque or "eggshell" stiffness that a flat slab lacks.  It doesn't take a lot of curvature to begin producing this effect.

I agree with Jerry that the greater accessibility of profiles (to controls and power train) is an advantage.

  

[Tom Niebuhr]

Jerry,

I don't know whether my statements about  profiles in the "Hobo" writeup prodded your forum questions on Profiles vs Built-up fuselages but I stand by my statements.

I have been flying stunt in competition since about 1959. I have had um teen people tell me that they are not ready for a built up fuselage, when the profile that they were flying was holding up there progress.

I have also had countless longtime fliers support my statement.

While there are a handfull of good flying modern constructed profiles, *( "Mo Best", "Forerunner" for example) most that are seen are old designs and/or reproduction of old designs with inadequate airfoils and moments, thin tail surfaces, and construction  that is both heavy and too flexable. This leads to vibrations and twisting that result in less than adequate engine runs, and poor flying characteristics.

There are modernized Ringmasters with lightened leading and trailing edges and lightened fuselages that are vastly improved, but still suffer from the thin airfoil. In the right hands they fly well, but this is far from an optimum airplane. The average low level flyer has no idea as to how to make these specialized airplanes.

The reality is that a simple fuselage is as easy, or easier to build, and yields a much better flying platform.

If someone likes Profile airplanes, that is OK.

To all: The "Hobo" is coming! It will provide accessability, convertibility, and simplicity. Several prototypes  will be seen very soon in the N.W., N.E, and South Central U.S. These airplanes will be used to prove out some new concepts.

[Jerry Leuty]

  Thanks Tom for your input. I have one of the prototype kits for the Hobo. I will start construction on it very soon as I get the yard in some sort of shape of decency. My yard is not my hobby but model airplanes are. But still I like a clean yard and spring is finally here after a cold and snowy winter in north Texas.

   My real thoughts are that profiles are great for kids, sport flying, and profile stunt contests. I have several profile planes and I do enjoy taking them up to my local airport for a couple of hours of flight time. I have had and built a lot of full bodied fuselages in my years of modeling. I do like them and their appearance. At VSC this year I do not remember seeing any profiles in the 'show and shine' event at the hotel.  After getting a wing built, stab and elevator, and rudder, it is really hard for me to put it all in a profile fuselage. Yet I still do some. I guess my thoughts are; Can an average pilot really tell a difference in a well trimmed profile as opposed to a built up fuselage?

   After working at the stunt pattern, judging stunt, and watching the top ten pilots go at it, I am convinced that this sport can be more frustrating than golf, bowling, or shooting pool. If you don't have the talent of an ace pilot then it is all just for fun. Which by the way at my age is all this is about anyway.

Jerry

[Larry Fulwider]

    . . . I have been told by some that they would never fly a profile and that profiles are called 'beaters' for what ever reason.  . . .

Steve Fitton flew an Imitation in the KOI fly-off in January -- and won! Well, the Imitation probably isn't what you had in mind when you posed the "profile" question -- or a Steve Fitton skill level at the other end of the lines.

       Larry Fulwider

[Perry Rose]

I hope the Hobo is a profile. Because that's what I named my Fancherized Twister.

[Kim Mortimore]

Are there any pictures of the Hobo available?  Sounds interesting.

[Larry Cunningham]

I agree with Tom about many profiles suffering from less than optimum aerodynamics. Maybe the best reason for building a (higher quality) profile might be for flying in the P40 event.   (There are also several older, beloved classic designs from similar times with airfoils which are too thin, stabs which are too small and thin, too short tail moments, lack of trim adjustment features, antiquated control systems, etc. as well as lack of power, making them less than competitive.)

If you end up spending as much time and effort (or more) on a profile than you do for a decent built up fuselage, there must be another reason than being convenient and simple.

One thing - I've heard some say that the "sidewinder" 9 o'clock engine position for profiles is undesirable and I don't agree. I like the accessibility of the engine as well as its lacking of flooding or fluid locking tendencies. Notice that 9 or 8 o'clock engine positions are found on some very competitive modern designs.

I remember well my dear friend Bill Melton building MANY profile (carrier) ships, typically two each month as long as I knew him. And Bill had solved the strength issues for profiles, using epoxy/fiberglass laminates. Those fuselages were absolutely rigid! Bill used the same extremely competitive notions for the entire model designs, like epoxy paint to stand up to 65% nitro.. Bill's stunters were always built up fuselages, made of the very lightest wood, finished immaculately in dope - a different paradigm. Bill's (and Jim Young's) beautiful Roadrunner is, in my opinion, an example of a classic era stunt ship whose numbers are less than optimum for today's stunt competition.

Photo: the late Bill Melton at a VSC, with Roadrunners by Gary Marchand, Lyman Lew, and Larry Cunningham

L.

PS - I wanted to demonstrate the quality of Bill Melton's stunt ship finishes, and to illustrate where he was headed with his
basic Roadrunner design - larger stab, long tail moments, .40 power, etc. Added photos, apologies for straying from the profile
subject of this thread.

"I coulda been Dan Blocker's stunt butt, I'll bet.." -Larry Cunningham

[Tom Niebuhr]

Perry,
The "Hobo" is not a profile. But it is very simple and very fast to build. Like the fuselage in one day, the wing in one evening. One of the prototype builders has already commented that it "snaps together".

Kim,
No pictures yet. Like I said it is in the Prototype stage.  There should be some flying in the next few weeks. Pictures from construction to flying will be coming soon.

More to come.

[Tom Niebuhr]

Ty,
Yep, in the future.

[afml]

Got a "sneak preview" at this plane and the HOBO is well worth waiting for!!!

All the "right stuff" with plenty of opportunity for "personal expression".

Got a winner fer sure!

"Tight Lines!"

Wes

[thomas farmer]

Jerry, the two major problems with most of the profiles. (1) a solid base to mount the engine,(2) a rigid fuselage. Both can be over come with some moderate changes in construction techniques. A big plus of a profile is like you said, accessibility.

[Brett Buck]

    I am curious. I have been at this hobby a long time now. I have flown lots of different type of C/L planes. Most claim that one will never get any good at the stunt pattern flying profiles. Aside from the aesthetic appearance of a model can you really tell the difference in flying the two? I have been told by some that they would never fly a profile and that profiles are called 'beaters' for what ever reason. I will continue to build both types. But the question is; Are you really a good enough pilot to tell the difference, if there is any, in the two models? If so what are those differences?

 If the wing and tail are held in proper alignment, it doesn't make any difference dynamically. But of course it's much easier and lighter to make a 2" wide fuselage stiff as a 1/2" wide fuselage, or, for the same weight, make the 2" wide fuselage much stiffer. And there's no such thing as "stiff enough". Even tiny deflections make a huge difference in the performance.  Stiffer is *always* better - it's just a tradeoff between the stiffness and the weight, and that heavily favors built-up fuselages. 

     The other issue is that it is generally easier to get good engine runs with the engine inverted (or upright, although I personally find them hard to start). That's a lot more true with "vintage" engines than current versions, but it's probably true to some extent with current engines for the most part. Mostly its a function of vibration, but the tank arrangement is generally superior, too

    The only downside to a built-up fuselage the relative difficulty of construction. Some of the "advanced profile" construction techniques make for a better ratio of rigidity to weight than solid wood, but then they tend to be just as hard to build as a built-up fuse. A "box" full-fuse with and exposed engine, a simple top deck, and a bubble canopy is pretty easy to build.

    Of course, you are not going to get as many appearance points with a profile, but unless you are trying to win Expert against NATs qualifiers, you can overcome it. Appearance judging is mostly about workmanship, and so with neat construction and finish you will only be a few points down to the very best. I can pretty well guarantee that you are making more than 3 points worth of correctable errors when you are flying!

     I wouldn't look down on profiles and if you can get a MODERN engine to run properly on its side, you aren't giving up much. But I would still recommend that you look into simple built-up fuselage airplanes, because they are marginally better in most respects, and you are going to need to figure out how to build one eventually anyway.

     Brett

[Perry Rose]

On my last two built up fuselages I filled the open areas over and under the wing and between the wing and the stab with foam. The same stuff foam wings are made from. I used Elmer's carpenters glue and made a tunnel for the push rod. It cost about a half ounce. javascript:void(0);

[Clancy Arnold]

Ask Jack Sheeks if a profile can fly as good as a built up body.  His answer is Mr. Ugly could.  Mr. Ugly was a SIG Banshee I built to the plans as marked up by Jack plus a couple of my personal changes.

Jack test flew it on it's first flight.  After take off Jack did a couple of loops then held it flat at 5 feet for 4 or 5 laps.  By this time I assumed it needed a lot of fixes but Jack then proceeded to put it through a complete pattern. After he landed it Jack said I could NOT fly my own plane until I learned the pattern.  Jack took it to the SIG contest that summer and won with it.  The next year he again took it and was the winner by two judges but the third judge had him marked way down.  After the contest he asked that judge what was wrong with his flight.  The answer Jack got was "Jack, you know that a profile cannot turn like a built up body model."  Jacks reply was "That one can."

I think that tells the reason this type of question keeps coming up.

The mods to the Banshee to make it a Bansheeks are:

Per Jack Sheeks,
1. Shorten the nose 3/4 inch.
2. Enlarge the stab and elevator to 22 inch span, 3 inch cord each at the center and 2 inch cord each at the tips.
3. Set up the controls for 30 degrees maximum up and down on the flaps and elevators.
4. Cut away a portion of the flap to clear the flap to elevator pushrod.

Per me,
1. Replace the 3/8 x 1/2 x 6 inch motor mounts with 3/8 x 1/2 x 12 inch motor mounts.
2. Extend the cutout in the profile body to allow the new motor mounts to touch the wing spars!
3. Sheet the wing leading edge with 1/16 balsa from the leading edge to the wing spars. Notch the wing sheeting to clear the new motor mounts.
4. Starting 1/2 inch behind the engine, cut out the profile body and right side doubler to allow the fuel tank to recess into the body and rest against the inside of the left side doubler between the motor mounts.
5. Place 1/16 balsa shear webs between the spars with the grain running vertical.
WARNING That wing had better be dead straight when you add the shear webs or any warps are now permanent!
6. Assemble the wing ready to cover then assemble the parts for the profile body around the wing and glue with epoxy.  When the epoxy has cured the wing and body are interlocked by the motor mounts and wing sheeting.

Clancy

[FLOYD CARTER]

No one has commented on one problem I find with the usual built-up with inverted engine; that is, you often have to flip the plane over for a start.  I really hate that!  I'm really pleased to find an inverted engine set-up that starts reliably when the plane is sitting on its wheels.  My good examples are Stalker 51 and S.T. 51.

Floyd

[Tom Niebuhr]

Floyd,

No problem with the "Hobo"

[John Hammonds]

Probably a slightly light hearted view on this but as someone who has only been flying for just over 12 months and any time I take all my models back home with no damage still being cause for a celebratory drink or 2 my entire fleet is profile at the moment. (They are all electric as well so I don't suffer the structural issues mentioned elsewhere).

But my main reasoning has always been if the only view I am going to get from the handle (Hopefully)... is a side view then that's good enough for me and improving it's appearance for the assembled masses viewing from outside the circle is not my concern.    Of course when (if) I get a bit better at this whole flying thing that view may well change. 

TTFN
John.
 

[Garf]

No one has commented on one problem I find with the usual built-up with inverted engine; that is, you often have to flip the plane over for a start.  I really hate that!  I'm really pleased to find an inverted engine set-up that starts reliably when the plane is sitting on its wheels.  My good examples are Stalker 51 and S.T. 51.

Floyd

Have you read post #2?

[Tom Niebuhr]

 Post #24 also answers it.

Watch for the "Hobo"

[john e. holliday]

Is there a picture?  Also is there a waiting list?  And last question, is it your design or did I not read something as usual?

[Tom Niebuhr]

Doc,

The "Hobo" is a brand new design by yours truly. It is muti-purpose Step-up airplane for Sport/Intermediate/Advanced. Easy and fast to build with no blocks to carve. Those who have had a preview are all enthused.

There are 4 prototypes being build: One in Oregon, one in Upstate NY and two in Texas. They should all be flying in about a month.

I'll send you a PM