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Converting C/L model to RC

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PatMc04/04/2020 23:05:17
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Here's some candidates with links to OZ for plans :

Scimitar ; Crusader ; Thunderbolt ; 334G & Stunt Queen.

I think the last pair would be my favourites with inset ailerons & enlarged to around 55" span.

Erfolg05/04/2020 01:14:36
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With the benefit of hindsight, I now favour the PM approach, rather than the path I choose.

PM seems to take the spirit of the earlier model, drawing/building a model which provides the facilities for the servos, cable runs, Lipo and so on, in conjunction with the constructional practices, and access to the interior, which are typical of this era, to achieve the functionality of take off, landing a level of stability needed as a RC model.

My mistake has been to adhere as closely to the original concept as is possible, only very reluctantly deviating from the original design.

I have also built another CL stunter by KK I cannot quite remember the name, other than the wing was a near triangle, in that case enlarged a lot. No pictures or model any more.

I would be perhaps tempted to go for an enlarged Team Racer now, the type that were almost semi scale such as the Mercury Mac or outlandish design such as the MAP Jabberwocky etc.

brokenenglish05/04/2020 07:33:43
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550 forum posts
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For the last few years, I have a partly finished CL Peacemaker that I now intend to finish as an RC version. The wing structure is finished, but not covered and with no bellcrank mount bits.

"One day", when I'm feeling brave, I shall finish it with the profile fuselage, and cutouts for he Rx and elevator servo.
Mounting aileron servos in the thick wing will be dead easy of course and no rudder will be needed.

Peter Miller05/04/2020 08:22:52
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What many people do not know is that George Aldrich did a Peaacemaker with a full fuselage as a plan in MAN

Outerzone have the plan here to download

**LINK**

It looked really good.

Just for fun, this is me flyinhg my Peacemaker from take off to landingmillers tales 73 001.jpg

Edited By Peter Miller on 05/04/2020 08:30:16

Keith England 105/04/2020 09:02:51
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Posted by PatMc on 04/04/2020 22:56:38:
Posted by Andy Stephenson on 04/04/2020 16:47:02:

CL models usually have zero dihedral to allow the control wires a straight run to the elevator bell-crank. If converting to one to R/C you might find significant adverse roll on application of rudder without adding a commensurate amount of dihedral to the wing.

A.

Care to explain why ?

If the vertical C of G is above the wing, as it will be on a low winger, then right yaw will induce left roll which is (to say the least) not expected behaviour for the pilot. For example, using rudder to counter adverse yaw from the ailerons would actually more than counter the ailerons instead and result in an opposite roll. A small amount of dihedral will cancel that out.
A good example, (which does look somewhat like a scaled up control line plane) is the Pete Tindals Excitation. Which had a massive wing cord and no dihedral. It flew very well and for years was very much my “go to” plane. But the lack of dihedral did make it very different to fly - it needed arm fulls of (say) left aileron when left knife edging or flat turning and vice versa when to the right.

Peter Miller05/04/2020 09:19:25
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Funny, My Moondancer doesn't show any strange characteristics like that.

Perhaps I am not a very good pilot.

Andy Stephenson05/04/2020 10:26:19
137 forum posts
21 photos
Posted by PatMc on 04/04/2020 22:56:38:
Posted by Andy Stephenson on 04/04/2020 16:47:02:

CL models usually have zero dihedral to allow the control wires a straight run to the elevator bell-crank. If converting to one to R/C you might find significant adverse roll on application of rudder without adding a commensurate amount of dihedral to the wing.

A.

Care to explain why ?

Pat,

I can explain why this is the case. The application of rudder not only tends to create yaw it also acts like a kind of aileron causing a rolling effect. With right rudder applied it tends to roll the plane to the left. We all know that on a rudder steered plane you need a fair amount of dihedral to induce a turn because the rudder yaws the plane then the forward going wing presents more air resistance which rolls it into the turn. There is a point at which if just the right amount of dihedral is applied the adverse roll effect of the rudder is cancelled out by turning effect. This why pattern ship designers always strive to get this just right to create the most neutral flying characteristics.

Andy.

Bob Cotsford05/04/2020 11:02:17
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Andy, wouldn't yaw/roll couple depend on a lot of factors, let's see if I can list a few. Fuselage depth, vertical position of the fin and rudder relative to the centres of mass and drag, vertical position of the tailplane, degree of aerodynamic blanking of the inboard wing when sideslipping and finally the dihedral. For reference you can look at any thread discussing mods to the Acrowot design, it was once a hot topic for debates. edit - nearly forgot the vertical angle of the rudder hinge line and dihedral/anhedral/sweep on the tailplane!

A second point - for most people yaw/roll couple isn't a real issues as ailerons are the primary turning control and coupling only gets discussed for precision aerobatics. Converting a c/l design would hardly come under that banner!

Edited By Bob Cotsford on 05/04/2020 11:04:35

Keith England 105/04/2020 12:09:13
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15 forum posts
Posted by Andy Stephenson on 05/04/2020 10:26:19:
Posted by PatMc on 04/04/2020 22:56:38:
Posted by Andy Stephenson on 04/04/2020 16:47:02:

CL models usually have zero dihedral to allow the control wires a straight run to the elevator bell-crank. If converting to one to R/C you might find significant adverse roll on application of rudder without adding a commensurate amount of dihedral to the wing.

A.

Care to explain why ?

Pat,

With right rudder applied it tends to roll the plane to the left. We all know that on a rudder steered plane you need a fair amount of dihedral to induce a turn because the rudder yaws the plane then the forward going wing presents more air resistance which rolls it into the turn.

I’m sorry but that is really not true at all, i have only ever flown one aeroplane, full size or model, that did not roll right if right rudder was applied - and that was the Excitation I mentioned above. it depends upon a lot of things but mostly where the vertical C of G is with respect to the centre of drag and diihedral. I got to fly a Taylorcraft plus D army observation plane and the pilot used to grip the stick between his legs and fly it completely on rudder leaving his hands free to operate the radio. it actually banked much better using rudder than it did using ailerons. Using rudder causes the outboard wing to move faster than the inboard and generate more lift, Hence banking the plane. it takes a very low wing without dihedral to counter that - which would be the case with some CL types - but certainly not if it was shoulder wing or higher.

But it is not so much rudder, as instability,  if a low wing CL plane is flown as an R/C without some dihedral it will be unstable in roll and only really comfortable to fly inverted.

Edited By Keith England 1 on 05/04/2020 12:16:13

Andy Stephenson05/04/2020 12:28:04
137 forum posts
21 photos

My explanation comes from several decades of model building and flying experience,

While aerodynamics is a complicated subject all I can say is I have actually seen these effects occur.

If you are not bothered about trimming for best performance then have at it.

A.

Erfolg05/04/2020 15:15:00
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11710 forum posts
1309 photos

My reduced scale Nobler, just flies like any other RC model I have, other than the poor roll rate when undertaking a full roll.

The only other issue is the ineffectiveness of the rudder, needs a lot of deflection to skid (yaw) the model. I put that down to the relatively small rudder chord, relative to the fin.

As a model, that is generally benign, it is fine, as a RC stunter my model is no great shakes. Although more power recently did help a lot, with response and climbing and even rolling. Power is what you need.

Mike Etheridge 105/04/2020 21:12:32
1544 forum posts
429 photos

I bought a Spectre kit from Heset Model Supplies in South Croydon when the owners were selling off the stock in the 1970's. I also bought a Veron Mini Concord, an Enya 09, an OS 10 RC a KK Marquis plus one other plane. As time would tell I was a pretty hopeless CL flyer, but my nephew Nigel was an expert and acquired the CL models. I helped him finish the Spectre and of course can remember that the wings were asymmetric,one wing being larger in span than the other. So an RC version would need the wings to be modified. Nigel may still have the Spectre but when I last spoke to him he said his old shed had partially collapsed squashing some of his old models. I still have the engines but the part complete fuselage of the Mini Concord was stolen from a garage.

PatMc05/04/2020 21:36:18
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4385 forum posts
524 photos
Posted by Andy Stephenson on 05/04/2020 10:26:19:
Posted by PatMc on 04/04/2020 22:56:38:
Posted by Andy Stephenson on 04/04/2020 16:47:02:

CL models usually have zero dihedral to allow the control wires a straight run to the elevator bell-crank. If converting to one to R/C you might find significant adverse roll on application of rudder without adding a commensurate amount of dihedral to the wing.

A.

Care to explain why ?

Pat,

I can explain why this is the case. The application of rudder not only tends to create yaw it also acts like a kind of aileron causing a rolling effect. With right rudder applied it tends to roll the plane to the left. We all know that on a rudder steered plane you need a fair amount of dihedral to induce a turn because the rudder yaws the plane then the forward going wing presents more air resistance which rolls it into the turn. There is a point at which if just the right amount of dihedral is applied the adverse roll effect of the rudder is cancelled out by turning effect. This why pattern ship designers always strive to get this just right to create the most neutral flying characteristics.

Andy.

Sorry Andy, I don't think that is a credible explanation. The leverage of the tallest fin/rudder would cause very little roll effect even on a zero dihedral low wing model. Apart from any other consideration, the small potential for "adverse" roll caused by the rudder would be completely negated by the fuselage blanking the slipstream over the inner part of the lagging wing as the model yawed, which would assist roll in the desired direction.

Erfolg06/04/2020 11:43:46
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11710 forum posts
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I changed one other important aspect, that was the thickness of the wing. The original was 18% NACA, no doubt to limit acceleration, and allowing smooth flight at high AoA. or the jargon of today, high alpha.

Having limited power, and being aware of the need to penetrate, I reduced the section to 10% NACA. It has little effect I am guessing on the stall characteristics. This is probably due to my efforts to keep the wing loading light.

Edited By Erfolg on 06/04/2020 11:44:10

Edited By Erfolg on 06/04/2020 11:45:06

alex nicol06/04/2020 13:01:03
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359 forum posts
15 photos

My thinking is to keep it simple. The construction will probably change quite a bit from the plan but the basic outline will stay the same as the Spectre apart from the fuselage wing/tail moment which will be increased somewhere in the region of 150 - 175% of current then the whole lot will be scaled up to about 140%ish. the fuselage may need to widened to accommodate the engine/tank set up ( probably going to be ic 46 - 53 size)

Erfolg makes a good point about the thickness of the wing section which I'll give some thought to, once I see what it looks like

I've got a couple of projects I need to get finished first then here goes ............

Erfolg06/04/2020 20:22:00
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11710 forum posts
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Alex

If going the IC route, power issues probably do not apply as critically. People tell me that a modern glow is far more powerful than they were 15 or so years back.

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