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Author Topic: Profile Fuselage Width  (Read 2774 times)

Offline Ken Culbertson

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Profile Fuselage Width
« on: February 04, 2021, 04:06:22 PM »
I have found the right profile fuselage width at 3/4" but I can't seem to find where that starts in any of our threads.  Obviously the nose can be thicker.

Ken
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Offline Brent Williams

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Re: Profile Fuselage Width
« Reply #1 on: February 04, 2021, 05:15:14 PM »
.750" at the trailing edge is what I have read.
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Offline Ken Culbertson

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Re: Profile Fuselage Width
« Reply #2 on: February 04, 2021, 07:32:12 PM »
.750" at the trailing edge is what I have read.
If that includes the flaps I am a happy camper.

Ken
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Offline Dave_Trible

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Re: Profile Fuselage Width
« Reply #3 on: March 25, 2021, 03:43:58 PM »
There really are no real written rules to define this.  Historically it's been a matter decided more on a local basis.  In most cases over the years in many places here in the midwest it is a max of 3/4" overall except perhaps a small cheek cowl like the Goldberg profile airplanes.  That means a build of 1/2" balsa with 1/8" plywood doublers each side-all the way to the nose.  I know in the last ....years this has grown into aborations of up to 2" in the nose area as long as it tapers back to something like 3/4" behind the wing.  To me (and simply my opinion) that comes close to defeating the spirit of 'profile'.  If I were to hold a profile event I would hold strictly to the 3/4" measurement.  I might give some leeway to a radial mounted engine but would still want to get back to 3/4" by the time we got back to the high point of the airfoil.  PAMPA went through quite a lengthy session attempting to develop uniform rules for 'Profile".  We ended in a stalemate.   Back to local rule.

Dave
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Offline Dan McEntee

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Re: Profile Fuselage Width
« Reply #4 on: March 25, 2021, 07:29:08 PM »
 The 3/4" measurement in the rule book is mainly for profile scale at AMA sanctioned events, I do believe. There is no official profile stunt event rules and the argument has been hashed thoroughly. My contention has always been that what constitutes a profile has been dictated by the endless number of kits produced over the last 60 years in that configuration and the limitless number of plans that have been published like wise. Also, what constitutes a profile is the sidewinder engine mount, like these kits and plans have demonstrated. A doubler or cheek addition on the inboard side really isn't problem to me as long as the engine is still a side winder mount. I have a built up model that I inherited hanging in my garage that a fuselage that is thinner than 3/4" at the trailing edge. that can raise the argument bar a little, and then asks the question, where are the control rods? Inside or outside?
   The answer to the question is, just build a normal profile! If you want to make use modern materials and construction techniques, have at it. It can be made plenty stiff to perform well and still look like a 1/2" slab e of balsa.
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Online Dennis Nunes

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Re: Profile Fuselage Width
« Reply #5 on: March 25, 2021, 07:50:06 PM »
The Northwest Regionals runs a profile stunt event. There rules are simple yet concise that allow for flexibility in the nose area. These rules work out well for both IC engines and electric motors. The maximum width according to there rules: "maximum 3/4" thickness by the trailing edge of the wing/flap hinge line".

The full set of rules are available here: http://flyinglines.org/rules.profilestunt.html


Dennis 

Offline Dave_Trible

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Re: Profile Fuselage Width
« Reply #6 on: March 26, 2021, 06:39:49 AM »
You can see, just in these post the two totally opposite extremes of thought on this matter.  In the second, you could take a fully built up fuselage airplane, saw it off at the trailing edge and stick on a profile fuselage aft.   Somehow this old timer finds that hard to accept as a profile.......

Dave

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Offline Ken Culbertson

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Re: Profile Fuselage Width
« Reply #7 on: March 26, 2021, 11:11:13 AM »
Electric has changed my opinion.  I was a "slab from prop to rudder" type but not having a place to put all of those wires and that can up front has moved me into the 3/4" at the TE camp.

Ken
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Offline Dan McEntee

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Re: Profile Fuselage Width
« Reply #8 on: March 26, 2021, 11:13:33 AM »
   I would be willing to to bet that the 3/4" rule for profile scale came about from people pushing the edge of the envelope. I would guess that fuselages got wider in order to present a little better in the side view, so they finally put a limit on it. I have some profile scale plans that I bought from some one that has some pretty thick fuselages so the corners can be rounded off to give the full 3D illusion. Not the same desire in stunt. People are looking to make them less prone top twisting with more structure. I just stick to the typical 1/2" slab look with a side winder engine,. I have built Rabe style noses before and they tend to get a little heavy, but the engines seem to behave a bit better for some people when up right or inverted. A plus in doing it that way if you don't have local rules prohibiting it. Some designs look better with it, I think.
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Offline Dave_Trible

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Re: Profile Fuselage Width
« Reply #9 on: March 26, 2021, 11:55:28 AM »
I actually think sometimes the old accepted rules were initially modified to slip in a couple airplanes that were designed as 'profile' before anyone thought much about a profile event.  I think these were meant as test beds or fast -build trainer types rather than to fly in a separate event.  Those would be the Rabe Mustunt I and Ted's Imitation.   If you just applied the old standard rules these could not be entered.  Now electric has provided other reasons. 

Dave
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Offline john e. holliday

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Re: Profile Fuselage Width
« Reply #10 on: March 26, 2021, 12:38:51 PM »
When electric started to be used it was recommended it be a separate class.  But, as usual it was incorporated into the rules to make it just one event.  I have watched many events start out as local events and do good until they became a national event which is why the rule book is so thick.  Yes, I can remember when there was just one event for racing, carrier, combat, scale and stunt.   Then we have people wondering why a low turn out for the events we have now. D>K
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Offline Brent Williams

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Re: Profile Fuselage Width
« Reply #11 on: March 26, 2021, 03:13:20 PM »
It's a heck of a lot easier to be inclusive rather than exclusive.  Have some fun.
For example, having the definition of a profile fuselage basically being defined by a maximum width measurement of .750" aft of the wing, opens up the competition to a broader range of competitors, designs, materials and importantly, innovation.  Be as innovative as you can be with your designs within that sole parameter.  Yes, it might yield some impressive, complex profile ships that are big and powerful.  However, as a direct counter-point argument to the impressive macho ships that some will build, I offer the legitimate example of Joe Gilbert and his simple Ringmaster as the giant slayer.  That Ringmaster is as far to the other side of the scale as one can be.  To that end, I would propose that you guys might drop all the antiquated profile definitions and limitations once and for all. Just let people have fun.

Run what you brung...and hope you brought *enough* (* ie, skills, experience, practice, oh and a good plane helps.)  Have some fun!       

And, as always...The biggest limiting factor IS ALWAYS going to be the guy flying the plane. Have fun!
« Last Edit: March 26, 2021, 11:10:35 PM by Brent Williams »
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Offline Chuck_Smith

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Re: Profile Fuselage Width
« Reply #12 on: March 27, 2021, 08:25:24 AM »
You know, you can build a foam core carbon fiber profile in a couple evenings and even at 1/2" thick it will be lighter and stronger than balsa. A lot easier to finish too. That takes all the thickness worry out of it.
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Offline Tim Wescott

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Re: Profile Fuselage Width
« Reply #13 on: March 27, 2021, 01:13:31 PM »
There really are no real written rules to define this.  Historically it's been a matter decided more on a local basis. (snip)

This.  The nice thing about it being local is that if you don't like it, you can always start hosting your own contest with whatever rules you want.

I like the Pacific Northwest rule of a 3/4" maximum aft of the wing TE -- 1/2" slab fuselages are still pretty competitive, and it's easy to make a rigid built-up fuselage out to 3/4" that's rigid enough so you're not tempted into a cf & foam airplane that's within 1/2".

On a plane with an engine, the best thing you can do if you have as much thickness as you want to play with is slap a cheek cowl on the inboard side, to absorb motor vibrations.  Any more is just wasted effort.  Again, allowing unlimited width is actually relieving the pressure on exotic kevlar/carbon builds that would do the same thing with a lot more effort.

Ultimately, there's no national records involved, which I think goes the furthest to keep it a fun event.  Yes, the people who fly the top levels of profile stunt around here show up with some pretty fancy planes -- but I can nip at their heels pretty hard with a Fancherized Twister, if not even win on occasion.

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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Tim Wescott

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Re: Profile Fuselage Width
« Reply #14 on: March 27, 2021, 10:40:40 PM »
I'll have to admit when I first saw a profile plane with a big built up nose I was scratching my head. Didn't look like  a profile to me. To each his own.


Motorman 8)

Well, yes.  But consider what the words "stock" and "car" mean, and then look at what NASCAR calls a "stock car".
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.


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