I guess it's a rather basic question but here goes:

I noticed the leadouts on scale models are usually outside of the wing.
It is perfectly understandable when the model has dihedral or is a bipe, but if it's a model with a straight or very little dihedral wing, is there a reason to still run the leadouts outside?

I like to have the leadouts at, or near, the vertical center of gravity of the model to promote wings level flight. For a lot of low wing scale models this results in the leadouts being above the wing.

The idea that it is important for the leadouts to be located near the vertical center of gravity is good.  Depending on the aircraft design, many low wing airplanes will have enough dihedral where the wing tip is not that far away from the vertical CG of a model replica.  Many WW II fighters would fall into this category.  Running the leadouts through the wing to exit the wing tips would not place the leadouts that far away from the vertical CG and using sufficient outboard tip weight to balance the weight of the lines will result in a model that does not fly with the outboard tip excessively high.  (On a CL scale model, the use of plenty of outboard tip weight is advisable up to the point that the amount is not ludicroously excessive.)  There are some full scale aircraft which would not adapt to this approach to run the leadout through the tips as well as others.  An inverted engine with an appropriately place fuel tank coupled with the landing gear design (as well as other factors) will all have a bearing on where the vertical CG is.

And has been discussed and shown on these forums before, the important part of leadouts position is their location relative to the CG.  The placement of the bellcrank can essentially be wherever it is structurally sensible to do so.

Keith

Thanks for the detailed answers! they certainly clarify the issue.

Regarding the tip on the ailerons - it certainly makes a lot of sense.
Question - is rudder offset not enough to ensure the model will always correct itself towards the end of the lines?

There is no limit to what I don't know and what I can learn on this BB.  I am about ready to put the first flight on my Extra 300S  I had never thought about vertical center of gravity.  But the big deal is I never thought about cranking in a little right turn with the ailerons.  I have them hooked up as control line flaps but I can adjust them seperately.  Cool and thanks!   

Or else it's time to add a servo and linkage for an electronic control that neutralizes the deflection for stunting. 

John
One benefit of the Aileron offset is that the amount of right bank is dependant on flight speed.  That is why I stated to adjust it to level the wings when flying at 10 to 15 feet.  When you slow down for your touch and go or landing, the amount of outboard wing droop will reduce and the model will land on both main gears at the same time.  Looks much better to the crowd, and more importantly, to the judges than a one wheel touch down.

You thought C/L Scale was going to be easy!!! LOL  LOL

John, a final thought, use the Ailerons during landings to help with line tension at the reduced speed when you are most vulnerable to wind gusts.

Good luck and hope to meet you in Muncie next year,

Clancy

I have found that tip weight is always there, because gravity is omnipresent.

At slower speeds, fixed aileron offset authority is reduced.

A balance of aileron offset and tip weight is best.

Aileron offset for aerobatics could become problematical.

John, if I were judging your flight and noticed that your ailerons were working like flaps on a stunt model, I would be deducting some points. Certainly in realism. Maybe in each maneuver that was "better" because of the flaps. In my opinion that is not a scale-like control surface movement. It is not spelled out in the rules, and other judges might feel differently.
Chuck

John, if I were judging your flight and noticed that your ailerons were working like flaps on a stunt model, I would be deducting some points. Certainly in realism. Maybe in each maneuver that was "better" because of the flaps. In my opinion that is not a scale-like control surface movement. It is not spelled out in the rules, and other judges might feel differently.
Chuck

We are talking about an Extra 300S.  It does not have flaps - only ailerons.  On a control line ship it is a little hard to find a good use for ailerons unless they act as stunt ship flaps.  If that is a NO-NO how am I supposed to get an eight pound, 64" wingspan airplane with a ST 90 swinging a 3 bladed prop to turn tight enough to do loops?  A tight loop for RC and a tight loop for control line are way different. We are talking stand-off scale.  During scale judging the ailerons will be displayed one up and one down.  I am new to all this so what do I know! An Extra 300S turns on a dime ---- so how do you do that?  I can't see geting good flight score with level flight -----

John,
the coupled flaps on a stunt plane actually do not speed up the corner, from my understanding, because of the nose down pitching moment they introduce they actually work against the corner. My no flap airplanes almost all turn tighter than my flapped airplanes.  I dont think that completing a loop or not being able to will be related to flaps or no flaps, I beleive tail authority and effectivness will have more bearing. that and the CG placement. Flaps generate lift,, tail generates rotation,, to put it simply,,

John,
we are talking apples and oranges here. well sort of. you are correct, when the elevator on a stunt ship goes down, the flaps go up. However, your concern was stated as not sure you would be able to do a loop without the flaps coupled into the elevator like a stunt ship. My opinion based on experience and what I have read, when using flaps on a stunter, its not about being able to turn tighter,, its about the quality of the turn, and being able to fly the corner. Flaps act as a stabilizing force and improve the quality of the turn. They do allow you to carry more weight in a stunter and still maintain turn. But I still stand by the fact that my flapless airplanes will turn as tight or tighter than a flapped airplane. you are not able to ""control"" the turn as well however. so in your case, the flaps will not really help you loop as much,,
one other thought, I thought that part of the rules for Scale was that all flight primary flight controls, (up and down) had to be controled by the flying lines? does your system of servoes on the Flaperons meet this or am I full of baloney on that part of the rules?

Mark, the FAI scale rules require that the elevator be mechanically controlled from the handle. The AMA rules do not require this. John's system is OK under AMA rules.

John, the event you plan to fly is called "Sport Scale." The better models don't deviate much from scale outlines. In R/C where there is a lot more competition the static rules are the same--the Top Gun models you see in the magazines are judged from a "stand off" distance.

The opinions that have been offered here have all been in good faith. Many of us learned this stuff the hard way; with these forums, you can get the "experience" for free. And of course you can decide that the free advice is worth what it cost you.

Now I am really confused!  With my setup when the elevator goes up both ailerons go down and when the elevator goes down both ailerons go up.  When doing an inside loop the up angle on the elavator forces the tail down. The downward moving aielorans create more lift forcing the noise up.  Why wouldn't this create a tighter loop?  If this not true why are all master class stunt ships using coupled elavator / aileorn setups?  The bigger question is considering that real aircraft never do it this way does such a setup hurt your flight realism score.  Am I to assume that most all control line scale aircraft have non functional (fixed) ailerons?  Remember I am talking stand off scale not pricision scale.   

Hi John,
The flaps will help your model because it is heavy. The elevator is probably large enough to over come the downward pitching moment that flaps produce. With them as large as they are, they would not have to deflect very much.

I wouldn't bother, as full points aren't a problem with the regular options. At 8 pounds the model probably won't do a loop in the room available. No sense in wrecking it.

You can build your next one just like a stunter and it'll loop. 
Weight must be kept down. Materials (four to six pound balsa, ply firewall, bellcrank mount and gear mount ONLY[yeah that ply spar, spruce stringers and bass whatevers, and fibreglass anything just have to go!]), etc) and control system (two micro servos, one throttle and one smoke, tiny batt pack as tip weight, no extras) must be lightweight.
Two pound motors are out, too. This is C/L. Use a 60, make your own lightweight muffler. Then it'll loop without flaps and be fine.
With C/L, weight is the enemy if one wants to acro. You must throw out everything that doesn't need to be there. R/C paradigm is totally different, leave it at the R/C field. Ask the Stunt guys what to do in the construction. Over 85 oz and it's not going to loop.

Scale guys build pretty heavy, so they are a great help with the systems, but the weight is the Stunter's area of expertise. If you want to acro in scale, you've got to use both C/L areas to get there, Stunt and Scale. That R/C stuff is baggage in the circle, leave it home.

Check your PM's, I sent you a message.

Chris...

Will,
I flew a Bee Jay that flew like that!
With the small % tail and low vertical cg position of the flaps because of the low wing position on the Pawnee, I'm not suprised of it's reaction!
Chris...

Clancy,
I want to use brakes on the two Tri-Pacers I'm starting - what brand do you recommend?  (One "Tripe" for sport scale and one for FAI)
Thanks,
Will

Chris,
In the case of the Pawnee, elevator truly was "elevating"!  (No music, though.)

Will
The brakes that I have on the Cessna 152 and also on my P-38 are DuBro units.  I do not know if they are still available.  They have a coil of wire around a drum.  The drum is keyed into the wheel hubs.  A servo pulls the coil tight on the drum stopping the model.  I bought mine over 25 years ago.  I have one on the nose wheel on the 152 and one on each of the main wheels on the P-38.  My C-7a Caribou had dual wheels on the nose and I had a "V" shaped plate that was pulled against the rear inside of the two wheels, almost out of sight.
Clancy

I think Rocket City used to make a brake. But of course Rocket City is no more.  By the way they were located in Huntsville Alabama.  Rick Chambers, one of the owners sons, still runs a hobby shop in Huntsville Alabama.  You might give him a call at 256 539-1347 to see if he has some old stock.