Setting up a model. Confusing but Mandatory?

[Avaiojet]

Still being new to CL model building, remember, I did have a 50 year layoff, and I know I haven't finished a model yet, but I'm getting close.  

I've noticed some things become obvious and other things are not.

Like agreement on set-up principals? Yes, a question mark because there's disagreement. Nothing wrong there, possibly different schools, or "What works for one may not work for another."

I'm fine with that.

In fact, I have respect for all opinions dealing with this subject.

I hate to assume, but one can assume that the setting up of a model begins in the building stage, or at least the thought of it should. Correct?

With that said, and not having set up a CL model in 50 years, in fact, the ones I built back then, weren't really "set-up" either.

Ya build the thing, couple of washers for engine offset and out to the field you would go.

Yes, I'm going someplace with this and trying to make it interesting at the same time.  

So, I'm ready to test fit and mount the engine on The LOSER.

I read the "Stone Tablets from Mount Sinai." Couple of times actually.

I'm confused more than ever? So, I have questions.

The model has the Dragonfly adjustable leadout and a weight box. So I should be fine there.

My interest is with the following:

Engine offset? How much if any?

Engine down thrust? needed or not?

Stab incidence? Really needed?

Thanks in advance.

Charles  

[Randy Cuberly]

Charles,
You're making this just a little more difficult than it has to be.
For the initial setup and first flights, set the CG at 15-18% of the MAC,  set the center of the two leadouts about 5/8 inch behind that, Put just enough tip weight in the outbosrd wing to make the tip drop slowly when balanced on center of the fuselage, put just enough offset (to the outside of circle of course) to insure that there is no inset, set up .015 braided lines to about 63 ft center of airplane to center of handle, get someone with experience to fly the first couple of flights.
Yes it could be more complicated...but it's not necessary for the type of airplane you're talking about, make sure the controls are very free and smooth...no stickiness allowed.  This should be a safe place to start and necessary trimming will have to go from the results of flying.
That's a whole different kettle of fish and should be done by someone who has successfully trimmed a stunter several times.
At any rate barring any realy serious warps or misalignments the above set up should get you flying safely.

Randy Cuberly

[Avaiojet]

Randy,

Thanks for the reply and input!

Are you saying I adjust the engine offset "after" the model flies and not in the building stage? Same with downthrust, if needed?

Charles

[Dick Pacini]

Deleted at the request of Charles.

[FLOYD CARTER]

Charles.  It sounds like you are doing all the correct stuff.  Usually, profile models require no engine out-thrust, and little, if any rudder offset.  Good line tension is primarily determined by position of the exit line adjuster.

Some recommend a tiny bit of stab Positive incidence.  I find this hard to measure, so I always set the stab on the fuselage centerline (wing at 0-0, stab at 0-0 and engine also at 0-0)

Floyd

[Avaiojet]

Charles.  It sounds like you are doing all the correct stuff.  Usually, profile models require no engine out-thrust, and little, if any rudder offset.  Good line tension is primarily determined by position of the exit line adjuster.
Some recommend a tiny bit of stab Positive incidence.  I find this hard to measure, so I always set the stab on the fuselage centerline (wing at 0-0, stab at 0-0 and engine also at 0-0)Floyd

Floyd,

Thanks for the reply and information.

The LOSER has the rudder with one side flat and the other with an airfoil. Don't know how that will play out, but I cannot change it. I've made enough changes allready including the building of another wing that isn't completed yet, could have built two models with all that work. I love the looks of this model and believe the effort will be worth it.

I know it probably doesn't seem so, but I like keeping things as simple as possible.

I like 0-0, 0-0, 0-0.

I will take your advice and set the engine, wing and stab up that way.

Thanks for the information and advice. Not to mention helping me with this decision.

Now I can move on.

I'm expecting a venturi and NVA from the UK any day for one of my R/C engines. I'll be looking for help on deciding which engine to place in The LOSER.

Thanks again! You know I appreciate it.

Charles

[FLOYD CARTER]

The airfoil rudder has the effect of rudder offset.  George Aldrich used the airfoil rudder on his NOBLER design.  I guess if no less an authority than Aldrich used it, it must be good!

Floyd

[Steve Helmick]

When I was a teen, I noticed that engine offset (right thrust) helped get the lines tight again quicker, when they did go loose. That can make a lot of difference in saving/not saving your plane. Still works the same.    Steve

[Leo Mehl]

I think it has been recomended by Fitzgeralt that .08 degres of stab positive incidence works fie for the stab. I have used this recomendation on several of my planes and it works very well. I don't think engine offset helps line tension at all but line adjustment makes a big difference in line tension.

[john e. holliday]

Remember, bak then before Rabe, Hunt and a few others, we did not have all the adjustable features we do today.  I remember Bob Palmer stating that on a new design/plane he might have to go in and adjust the placement of the leadouts on a plane.   Also in another article he found out by accident a missing rudder did not hinder the flight of a plane.   Almost all the planes back then showed some engine off set to the outside of the circle to maintain or get line tension.   We were also taught to build light and straight.   Only did we have to make adjustments when a plane had a small warp or the CG was wrong.   I have seen in the past guys go to a contest and start changing things on a plane bacause it didn't feel right and adjust themselves out of competition.  One in particular was a local flyer at his first NATS and another that left a contest because he got everything out of kilter.  I have planes that have most of the adjustment capability that has never been used except for the leadout guide or nose weight.   

I built, setup and flew Ted Fancher's "DOCTOR" according to what he wrote.  It was still flying great when I gave it to a newcomer to stunt.  All he has to was fix the broken spar that I though I had fixed after Dave Fitzgerald  pointed it out to me.    Anyway every body has their way that works and that is fine.

[FLOYD CARTER]

I'd be interested in knowing just how you can even hope to measure .08 degrees!  Someone estimated 1/32" up at the front of the stab.  Normal construction, even being very careful, could cause a variance of 1/32" either way.  It is far easier to crank in a tiny bit of elevator DOWN after test flights, by means of a threaded clevis, and only if hunting is experienced.
F.C.

[Bob Reeves]

I'd be interested in knowing just how you can even hope to measure .08 degrees!  Someone estimated 1/32" up at the front of the stab.  Normal construction, even being very careful, could cause a variance of 1/32" either way.  It is far easier to crank in a tiny bit of elevator DOWN after test flights, by means of a threaded clevis, and only if hunting is experienced.
F.C.

You amplify the measurement with a straight edge. 12 inches in front of the stab you are measuring 1/2 inch or something like that, can't remember the exact number. Have it written down in my shop.

[FLOYD CARTER]

The biggest problem I have is setting the wing at 0-0.  After shaping the leading edge, the exact center of the airfoil is a bit nebulous.  Add the problem that the usual fuselage cutout isn't exact, but close, and your wing could end up with a tiny bit of incidence, either way- with respect to the stab.

As careful as I usually am, sometimes it will take some elevator adjustment after test flying.  Just one factor in the long trimming process.

F.C.

[Chris Wilson]

 So ....... the questions put to a panel of experts to fight over are  - how much engine offset, tail incidence, rudder cant etc are needed on an untested and unknown model, intended use unknown, and about to be evaluated by a raw beginner who may or may not know, appreciate or be able to evaluate what the effects are anyway?

That has got to be the equivalent of chucking a raw steak into a pit of hungry lions Charles - every lion will come up with a different answer on how to 'get that steak.'

And anyone who provides a specific answer has to be guessing and is going to be pounced upon by the other lions for being 'oh so wrong.'

Or is this your intention here?

You are going to be more confused by the variety of answers than anything else and I don't see the point in this at all, sorry.

[Avaiojet]

...

 And anyone who provides a specific answer has to be guessing and is going to be pounced upon by the other lions for being 'oh so wrong.'

Or is this your intention here?

You are going to be more confused by the variety of answers than anything else and I don't see the point in this at all, sorry.  

Chris,

Thanks for the reply.

With all due respect, it's unfortunate you view this Thread, or the purpose of it, that way.

First of all, I have enough respect for Robert, the Forum and all the "participants/modelers," especially those who gladly donate their time and offer assistance with all cries for help, including mine. I would never place a Thread for the reason you described. That thought would never come to mind.

With that said, what prompted this Thread, and I believe I clearly mentioned the reason, was the information offered in the "two sheets" of text describing "the set-up of a model," actually before flight.

I need opinions and information, because I'm close to bolting in engines and attaching stabs and rudders, on a few models I'm working on.

There's no point in doing this wrong or incorrectly, and making a guess can be a mistake, especially on a model that is built with the spinner aligned with the fuselage. Once the model is complited, a degree change would be obvious with spinner alignment.

As suggested, I've incorporated adjustable leadouts and weight boxes in all my building. Not a bad start.

The other, more complicated information, of which I can only guess at, I'm seeking from the more experienced.

Sure, there will always be "areas" where disagreement exists, and that's really not all that bad a thing.

What's better than receiving "first hand" information from experienced modelers "who have been there and done that?"

It's been a great informative Thread and much advice can be taken away from it.

My many thanks and appreciation goes out to all modelers who have participated.

Thank you!

Charles

 

[john e. holliday]

In my few years of buildidng and flying model planes, FF, RC and CL.  I always figured the designer and manufacturer knew more than I did.  So that is why so many were built according to the article or the kit plan.   Then when all was done, it was flown.   There are parameters for anything and I tried my best to stay within them when I scratched or tried to design a plane.   My first successful rubber powered plane was from what I read in a little booklet that was put out by America's Hobby Center that used to advertise in the magazines.  Most of my supplies came from them, because the closest hobby shop was a half days drive for my parents back then.    Anyway I am still building according to the design with some of the things I have learned thru the years.   Main thing is  mounting hardware.