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Aeronca Sedan

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Erfolg03/06/2020 16:08:45
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In probably the 1950s the Aeronca Sedan was quite a popular aircraft to model. A number of kit producers had one in their range. Probably in the UK the Mercury Kits version was most popular, although on the various USA plan sites there are many others.

At present i am building a version for RC flight, even with re-rigging AoA and so on, I anticipate the model will tend to have a flat slow speed approach to landing.

I have struggled to get ant real in depth information with respect to the Sedan. No book seems available, I have not found ant full size drawings or rebuilds/restoration images of a Sedan.

I am working from something approaching a thumb nail drawing found on the internet.

The important thing to me, it shows flaps, inboard of the ailerons. Yet when i look at photos (again on the internet) I cannot see any evidence of the Sedan having any.

My question is, did the Sedan have flaps, if so, what type. The reason i ask what type, I wonder if fitted they are of the Split Flap type, that hang down from the undersurface? Or something else?

Can anyone help, do you have information?

J D 803/06/2020 17:06:25
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1496 forum posts
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Hi Erfolg, A fellow club member had a thing about Auster's and Aeronca's Both Aeroncas a Champion and a Sedan were quite large models, one about 70" span the other 85ish. Both were good flyers. The smaller was retired a couple of years ago after much use due to a bad wing warp setting in. The other is still around.

Sedans came with or without flaps, they may have been an optional extra. Have a look at backcountrypilot.org for more info.

John.flight line

Champion next to my Major Mannock.

Nick Cripps03/06/2020 17:36:25
50 forum posts
18 photos

Some good information here, Erfolg:

N331H

Richard Clark 203/06/2020 19:58:46
292 forum posts
Posted by Erfolg on 03/06/2020 16:08:45:

In probably the 1950s the Aeronca Sedan was quite a popular aircraft to model. A number of kit producers had one in their range. Probably in the UK the Mercury Kits version was most popular, although on the various USA plan sites there are many others.

At present i am building a version for RC flight, even with re-rigging AoA and so on, I anticipate the model will tend to have a flat slow speed approach to landing.

I have struggled to get ant real in depth information with respect to the Sedan. No book seems available, I have not found ant full size drawings or rebuilds/restoration images of a Sedan.

I am working from something approaching a thumb nail drawing found on the internet.

The important thing to me, it shows flaps, inboard of the ailerons. Yet when i look at photos (again on the internet) I cannot see any evidence of the Sedan having any.

My question is, did the Sedan have flaps, if so, what type. The reason i ask what type, I wonder if fitted they are of the Split Flap type, that hang down from the undersurface? Or something else?

Can anyone help, do you have information?

This is a good site on the Aeronca Sedan:

n1331h.com

Richard Clark 203/06/2020 22:41:21
292 forum posts

PS:

If you want it 'really accurate' bear this in mind.

Like the Piper Cub the fin fairs into the fuselage via the cloth covering with no clear distinction between the fuselage top and sides and the fin itself. This is near impossible to do with film over an open structure so I suggest you 'fill in' the relevant area with slightly over-thickness sheet and carve/sand it to the correct shape, which will be slightly concave. Then film cover it using low heat in this area which will stick the film without shrinking it much anf pulling it out of the (very slight) concavity. Neither the Mercury nor the bigger US Pica kit got this right. Mostly due to the rear cross section of the fuselage being too bulbous at the sides in both cases. In reality the rear cross section of the fuselage is roughly triangular with a rounded underside and the stringers end some distance before the tailpost. leaving only the basic 'three tube' triangular structure.

Also on the Mercury plan (Outerzone and an old article by a Mr Deadman in RCM&E) the rear top of the Fuselage near the wing TE is flat and ends at the wing TE. In reality the top is higher, curved all the way, and ends close to thr centre of the wing chord.

DO NOT OMIT the front and rear 'flying wires' that go from near the bottom of the fuselage, via the tailplane to near the top of the fin. The tailplane seat is very narrow and this section of the fuselage is likely to be somewhat flexible and the tailplane and fin may flutter without them. I fitted small brass tubes using 12-24 hour Araldite, the only epoxy which will genuinely stick metal. I added the wires after covering, not forgetting to prick the film before covering the other side to mark where the holes are.

Erfolg04/06/2020 00:40:55
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11750 forum posts
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I thank you all most sincerely, for your help.

So far I have been reading Nicks link, there is a lot of material there.

As yet I have not followed the link of JD. I had assumed that no Sedan had flaps, as non can be seen in the various photographs when Googled. I had come to assume that my drawing was incorrect.

I have read Richards contribution with interest, particularly the bracing wires on the tailplane. I had been worrying quite a bit with respect to the narrowness of the mounting. I seem prone to bashing tailplanes, just moving the model about.

In many ways my drawing will not be totally accurate as my internet sketch is very small, and there will be scaling errors as i have scaled up, mainly using proportional dividers, I mainly drew my own drawing as a consequence of the horror, that some expressed of my intention of modifying a Mercury kit I have. After considering the objections, I came to the conclusion that in some, perhaps many peoples opinion I was going to commit sacrilege. Also the changes meant that I would throw much of the kit in the bin.

I am a good way into a new build, but I have worried that in reality I have so little information on the real aircraft, and have perhaps guessed a lot, and based many details on the various kits/drawings. Your help is and will help a lot in understanding how to go forward. In many respects my model will not be accurate, having more emphasis on flying well in the +10mph wind speeds that dominate my clubs field. Yet like most modellers, I do not go out of my way to be inaccurate.

Richard Clark 204/06/2020 07:22:50
292 forum posts

Erfolg,

The N1331H site gives a huge amount of information with lots of pictures. of its total rebuild in Switzerland (the site is in English). Plus articles on the Mercury one with links to Mr Deadman's rather unsuccessful (initially) build of the Mercury kit, Also an article about the Pica one and a 'giant scale' one.

I venture to suggest you stick to the colour 'layout' of N331H if not to the actual colours. In flight the finer points of the Aeronca don't really show and the fin stripe and the curved painted area behind the cabin windows was the standard factory scheme and at a distance is very distinctive and is about the only thing that distinguishes the Aeronca from all the other high wing US light aircraft.

Mine is made from the Vintage Model Co replica of the Mercury kit. I made minor changes to it for rc. A one piece wing to avoid the need for functional struts (though mine are actually functional but don't need to be), 1/8 square spruce wing spar reinforcement replacing the outer 1/8th edges of the upper and lower spars, no downthrust plus a little positive incidence on the tailplane, two 3mm carbon rods from the bottom of the fuselage through to the top of the fin, also acting as tailplane locators for glueing, some similar carbon rod reinforcement in the window and windscreen area.

And above all slightly larger than scale ailerons, with 50% differential. Don't believe all this garbage from the 'experts' (who have probably never actually tried it) about ailerons not working well on dihedralled high wing planes.They work perfectlty well even on my standard steep dihedral Junior 60.

Mine is very light. Much lighter than my Ben Buckle (who tend to use very hard and thus heavy balsa) Junior 60. You certainly won't need flaps, though they do have an entertainment value. You might even be able to do a Fieseler Storch tribute act.

Erfolg04/06/2020 10:11:12
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11750 forum posts
1337 photos

Thanks for your contribution Richard.

I have redrawn the wing to be fully sheeted, for a number of reasons.

I have changed the wing section to Clark Y, the kit section certainly does not equate to the Profi or a similar template I have for the profile. Much of my reasons are about wanting a broader viable speed range and the original section was modified to encourage a one speed flight pattern, where drag was not foremost in the designers mind set.

My intention is also a one piece wing, as much about getting into the body for servos etc.

As for the dihedral, the full size seem to have little if any. Peter Millar reckons it is a a degree or so (no reason to disbelieve him).

I have drawn the wing and tailplane to 0-0, the wing will be still generating lift, whilst the tail will need to possibly generate a little down force.

Which leads me to down thrust. I have drawn this also to zero. I have debated where the drag centre would be and if down thrust would help in balancing forces, foe a particular speed. On that score I am very interested in your experiences.

Perhaps what has really interested me is that there appears to be many modifications (mostly in detail) that have been undertaken. I guess that USA and perhaps Canadian regulators are not as bureaucratic as in the UK.

Edited By Erfolg on 04/06/2020 10:12:54

Peter Miller04/06/2020 10:24:51
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11104 forum posts
1309 photos
10 articles
Posted by Richard Clark 2 on 03/06/2020 22:41:21:

PS:

If you want it 'really accurate' bear this in mind.

Like the Piper Cub the fin fairs into the fuselage via the cloth covering with no clear distinction between the fuselage top and sides and the fin itself. This is near impossible to do with film over an open structure so I suggest you 'fill in' the relevant area with slightly over-thickness sheet and carve/sand it to the correct shape, which will be slightly concave. Then film cover it using low heat in this area which will stick the film without shrinking it much anf pulling it out of the (very slight) concavity. Neither the Mercury nor the bigger US Pica kit got this right. Mostly due to the rear cross section of the fuselage being too bulbous at the sides in both cases. In reality the rear cross section of the fuselage is roughly triangular with a rounded underside and the stringers end some distance before the tailpost. leaving only the basic 'three tube' triangular structure.

This is not hard to do in the scale way.

If you can find it I describe how to do this in the scale way in my Peggy Sue 2 build article. Also see Mark's Peggy Sue build.

Orginally the method was described in the Sig Piper Cub kit.

The pictures showsmy Paggery Sue 2 fin. Marks Build blog shows the same area very well

peggy sue2 blog 008.jpg

It takes some patience and care but works well

Erfolg04/06/2020 11:46:52
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11750 forum posts
1337 photos

I will try and find the Peggy Sue blog, I am guessing that where the technique is given?

The idea of flaps really stems from experience. Mostly to do with my Billkits Slingsby Firefly, which floats on after clearing the hedge to the strip, it would benefit from some drag imparting device, whilst keeping the tips lifting. On the other hand my high wing trainer does not have the same characteristic. The Mercury Aeronca has a reputation for being a floaty, low wind, evening flyer. It is these counter characteristics, that brought me to the idea of flaps, in that if needed they would be there, if not, no problem. I have come to the conclusion that flaps will not be incorporated.

I am a very much stand off, practical model, scale type of person. Particularly after my father pointed out that a outstanding scale spitfire or something similar, would have had rivets heads in the region of 5/8" dia if the detail was scale. He then noted that very few, if any full size aircraft at the time had smooth surfaces that most model aircraft have, being quilted due to riveting. He finally finished saying if he fitted panels with such large gaps between panels, as the inked lines suggested, the inspectors would have more than commented. From that point onwards, it is general shape for me now, forget the super detailing and high levels of skill that many (unlike myself) achieve.

Edited By Erfolg on 04/06/2020 11:47:27

Richard Acland04/06/2020 12:47:22
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116 forum posts
37 photos
Posted by Peter Miller on 04/06/2020 10:24:51:
Posted by Richard Clark 2 on 03/06/2020 22:41:21:

PS:

If you want it 'really accurate' bear this in mind.

Like the Piper Cub the fin fairs into the fuselage via the cloth covering with no clear distinction between the fuselage top and sides and the fin itself. This is near impossible to do with film over an open structure so I suggest you 'fill in' the relevant area with slightly over-thickness sheet and carve/sand it to the correct shape, which will be slightly concave. Then film cover it using low heat in this area which will stick the film without shrinking it much anf pulling it out of the (very slight) concavity. Neither the Mercury nor the bigger US Pica kit got this right. Mostly due to the rear cross section of the fuselage being too bulbous at the sides in both cases. In reality the rear cross section of the fuselage is roughly triangular with a rounded underside and the stringers end some distance before the tailpost. leaving only the basic 'three tube' triangular structure.

 

This is not hard to do in the scale way.

If you can find it I describe how to do this in the scale way in my Peggy Sue 2 build article. Also see Mark's Peggy Sue build.

Orginally the method was described in the Sig Piper Cub kit.

The pictures showsmy Paggery Sue 2 fin. Marks Build blog shows the same area very well

peggy sue2 blog 008.jpg

It takes some patience and care but works well

Funny this topic should come up now. I am just about to start covering my Stolp Starlet. I notice that the tailplane is the same whereby the covering runs from the fuselage side to the fin assembly. It all looks a bit tricky to me.

Edited By Richard Acland on 04/06/2020 12:49:03

Edited By Richard Acland on 04/06/2020 12:49:43

Richard Clark 204/06/2020 13:14:47
292 forum posts
Posted by Peter Miller on 04/06/2020 10:24:51:

This is not hard to do in the scale way.

If you can find it I describe how to do this in the scale way in my Peggy Sue 2 build article. Also see Mark's Peggy Sue build.

Orginally the method was described in the Sig Piper Cub kit.

The pictures showsmy Paggery Sue 2 fin. Marks Build blog shows the same area very well

It takes some patience and care but works well

Peter,

Thank you for that. I couldn't find yours but I did find Mark's superb build and with patience it doesn't look particularly difficult.

The Aeronca is more difficult. From the centre line of the fuselage side where the scale colour change usually is it is curved in all directions so I stuck it down, pulling out wrinkles stringer by stringer with gentry applied local heat and hoped for the best (which worked well) and covered the fin separately, leaving a temporarily loose 'skirt'. each side to slightly overlap the fin/fuselage join when I glued the fin on.

And the high tailplane attaches just above the base of the fin and 'interrupts' where the fuselage/fin curve is.

As I said, even the otherwise very carefully designed Pica kit failed at this point - it used a crude triangular sheet 'wedge' which looks less realistic than not attempting it at all.

I was running low on white film so I didn't even try . But thanks anyway. If I ever build a Cub I will try it.

Richard Clark 204/06/2020 14:33:33
292 forum posts
Posted by Erfolg on 04/06/2020 10:11:12:

Thanks for your contribution Richard.

I have redrawn the wing to be fully sheeted, for a number of reasons.

I have changed the wing section to Clark Y, the kit section certainly does not equate to the Profi or a similar template I have for the profile. Much of my reasons are about wanting a broader viable speed range and the original section was modified to encourage a one speed flight pattern, where drag was not foremost in the designers mind set.

My intention is also a one piece wing, as much about getting into the body for servos etc.

As for the dihedral, the full size seem to have little if any. Peter Millar reckons it is a a degree or so (no reason to disbelieve him).

I have drawn the wing and tailplane to 0-0, the wing will be still generating lift, whilst the tail will need to possibly generate a little down force.

Which leads me to down thrust. I have drawn this also to zero. I have debated where the drag centre would be and if down thrust would help in balancing forces, foe a particular speed. On that score I am very interested in your experiences.

Perhaps what has really interested me is that there appears to be many modifications (mostly in detail) that have been undertaken. I guess that USA and perhaps Canadian regulators are not as bureaucratic as in the UK.

Edited By Erfolg on 04/06/2020 10:12:54

The much derided Clark Y is an excellent section. Set at a true zero datum it is little different from a symmetrical section but is rarely used at a zero datum (though it was on Lindberg's Spirit of St Louis).

Dihedral is not needed. on most full size planes. It is mostly there to avoid a 'droopy' appearance on low wingers and few high wingers have any except that on Cessna high wingers the flat top of their tapered thickness wings makes it look as if they have on a quick glance.

Downthrust. It was only ever there to assist the uncontrolled crash on unknown ground that is a free flight 'landing'. To do this the wing is put at a very high AoA giving high lift which the downthrust works aqainst, stopping continuous loops. When the engine stops the downthrust ceases, the plane slows down and produces the lowest possible speed crash. As rc models have elevators and a rudder we can don't need any of that nonsense as we can control the speed and (usually) choose the landing area.

Floaters. Floaters are 'accidentally' and 'temporarily' created because a large number of modellers don't have the foggiest idea how to set up an approach.

Nigel R04/06/2020 16:01:30
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3925 forum posts
685 photos

"The much derided Clark Y is an excellent section. Set at a true zero datum it is little different from a symmetrical section but is rarely used at a zero datum"

It is. Although much of its bad press comes, I think, from people eyeballing 'one of them there wing sections' or drawing round a handy size 10 boot and calling the result a Clark Y even though it bares little resemblance.

Erfolg05/06/2020 12:02:03
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11750 forum posts
1337 photos

I think that a lot of floaters are a combination of one speed sections and a very low wing loading.

In the case of my model I am not sure at all what the wing loading will be as yet. I normally do a calculation with kits, which normally equates to the kit in the box, plus my motor and Lipo (I now only fly electric). This ball ark estimate is pretty accurate, even though it ignores waste materials, or the additions such as servos and Rx (these days both are low). Then divide the weight in oz into the wing area. To date i have not undertaken the process.

I agree that Clark Y is a OK section for power models, totally outclassed by some of the more recent glider type sections. The flatness of glide slope and speed range of these sections used to encourage dawking the model. or spoilers of some type for landing.

As has been pointed out, as RC models, we require different characteristics to both FF or Gliders. I want a section which does have a good speed range, without a massive increase in drag, as heavily cambered sections typically exhibits. Yet when opening or closing the throttle, I want the model to go up, down, or slightly re-trimmed a different flying speed . Clark Y seems to be a good compromise in this respect, in conjunction with reasonable stall characteristics.

Erfolg05/06/2020 12:15:15
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11750 forum posts
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I have just done a quick calc, a ball park figure of +17 oz per foot square. I doubt it will be to much of a floater.

Nigel R05/06/2020 13:10:22
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3925 forum posts
685 photos

Clark Y has the obvious and useful distinction of making it possible to do a complete dead flat on the board build, if the spar is at the 30% (?) high point - this ease of accuracy is worth quite a lot.

What glider section would you use instead, erfolg?

BTW, what wing area will it have?

Erfolg08/06/2020 11:20:27
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11750 forum posts
1337 photos

I have used E205, E387, today I would look at MH 32 (If I could build it accurately).

I have built models with all of them, they all work, from memory TH Clean sweep used E387. When returning to modelling one of my first gliders (small at 36" ) was built with two wings. Clark Y and HM 32. The HM 32 was far superior to Clark Y, in that at speed or a strong wind, it would penetrate without ballast and not loose an awful lot of height, which Clark Y tends to. It is the same with E205, a far broader speed range. In the case of power models, a bit of drag, is not quite such an embarrassment, often helping with landing, making the throttle use more useful.

The area is approx 3.5 ft^2

Edited By Erfolg on 08/06/2020 11:21:07

Edited By Erfolg on 08/06/2020 11:21:25

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