Mercury kit, Aeronca Sedan

[Erfolg]

I have a Mercury Kits Lumscombe Sedan, which I intend building as a RC model.

The kit is for FF, with some guidance for RC conversion, although clearly for very early equipment as the rudder is diminutive and for elevator use only.

I am sure that many of these kits will have been operated as RC models. Perhaps more usefully many will have been in more recent times been converted to modern equipment, such as ailerons.

The kit also suggests a 1.5 cc diesel and not to overpower using something like a 2.5 cc. Again some pointers as to what size engines have been used and the performance of the model.

So, guidance and feed back wanted!

[PatMc]

Erf, do you mean the Aeronca Sedan ?

AFAIK Mercury didn't make a kit of a Luscombe Sedan, Veron did but it was a 24" rubber powered model.

[Engine Doctor]

Hi Erflog . I havent built that particular model but have converted many vintage scale types for radio control. As you have said they all seemed to have very small rudders used as trimming tabs . Double the size of the rudder if possible or as big as you think you can reasonable build it . A larger rudder with smaller movement is far more efficient and smoother to use. the elevator need not be too big as its not an aerobatic job.

Another thing I always do is replace any balsa wing spars with spruce . Dont go over board on size though If it has a 1/4 inch spar top and bottom I would laminate some 1/8th by 1/4 balsa and 1/8 by 1/4 spruce t make a strong but light spar.. Smaller sars I just replace with same sized spruce.

as it was designed for F/F the wing incidence may be too high so check before building .

Do you want to use a period diesel ? They are fun if a bit smelly but that's the charm .What span it the Luscombe I currently have three converted free flight jobs in the garage. A Frog 45 and a Taylor craft . Both fly very well on a Frog 150 diesel running at about 1/2 to 3/4 power . My twice size ladybird flys superbly with a Enya 60 FS at a fast idle .i would go for the 1.5cc A Frog or a DC saber would probably suit or even a AM 15 from the same stable .

Good luck and lats have some pics .

[Robin Colbourne]

Maybe its this one?

**LINK**

Plan here:

http://www.vintagemodelcompany.com/user/products/large/5097f2810de044.84779095.gif

 

If you are going to fit a throttle, then you could afford to go a little bigger on the engine size, even up to a 0.21cu in. if the structure will take it. It all depends how you plan to fly, do you want a guided free-flighter, or a typical r/c sport model?

Bear in mind engines have got more powerful over the years, so even a modern engine in the recommended range is going to be more powerful than the maker intended. If you are considering glow, think about the size and position of the silencer. You might get a small engine and silence in the cowl, whereas a larger engine may need a dustbin silecer or a standard one outside the cowl.

A diesel can turn a much larger prop than a glow engine, so a 0.10 (1.6cc) glow engine may end up with an 8" prop which barely extends beyond the cowling, whereas you can adjust the compression on the diesel to turn an 11" prop, albeit slowly!.

 

Edited By Robin Colbourne on 06/01/2016 17:48:51

[kc]

A clubmate had a Mercury Aeronca Sedan which had been flown for about 50 years eventually on RC and last year it had ailerons fitted. Much better for RC with ailerons.

It was electric powered in recent years. Eventually was wrecked this year when a strut fixing failed and the wing folded. Be very careful with strut fixing method!

[Merco 61]

I built my first one circa 1961 as per plan,nylon covered,elaborate polyurethane finish,no attempt at keeping weight down,1.5 PAW.Flew free flight beautifully for several years.Power more than enough.Built a second to carry single channel-on rudder with second cascaded escapement to give throttle control but this time with a plain bearing 2.5 diesel.Far too much power,so always flown with engine under-compressed but again flew sedately and gracefully for many years.Little inset rudder gave plenty of authority.The UC would always swing rearwards upon landing, so the crude "stops" needed regular replacement.Construction is straightforward and provided the builder is au fait with trad techniques eg pre steaming stringers and hard longerons there are no particular difficulties.If the excessive dihedral offends,I suppose this could be reduced to allow dual aileron servos to be installed but then it would no longer be a Mercury Aeronca,would it? A modeller quite regularly flies a very nice example in the Bowden at the Nats,free flight of course but with an Oliver 3.5.I think he is brave. In my humble opinion,a first class British kit which can be built into a fine model of a very attractive American aeroplane.My pal regularly flies his 1960s example,with bearers arranged to accept a variety of diesels from 1.5 up to a 2cc ED Comp Special,just as a flying test-bed. In the air,it looks a lot bigger than it really is.Lovely.Real aeromodelling.

[John Timmis]

Hi

I remember building one of these back in the 70s. Nice traditional build. Covered it in nylon. I think it had an OS25. Not over powered as I remember.

Good luck.

John

[Erfolg]

Patmac and others are correct, it is an Aeronca Sedan.

My intention is to go electric.

I will be fitting a servo per aileron.

Looking at the plan more carefully and reading the instructions, it was a single channel model.

Although I do look sympathetically at how a model was originally conceived, I usually take the view that if the present day equipment was available back then circa 1950-60 it would have been used.

In general tend to try and make a model as similar as is reasonable to the full size, to be a practical everyday model, rather than be saddled with the constraints of the distant past.

I will make the rudder component and elevator as near to the original proportional size as is possible. Although at this stage I have no idea what that is.

It does seem that I have been lucky as I have not paid the price that is indicated on the link to the replica kit.

I will look carefully at how the wings are attached, to ensure that they cannot easily come adrift.

[kevin b]

Nice kit Erfolg. I assume you are covering it in tissue as per original ? These days, if you are building a "pretty" model there really is no alternative than to go electric. I do like I/c, but if you want a model to keep its looks for any length of time then you need to avoid fuel ingress. In practice this is almost impossible with I/c, no matter how hard you try !

With regards to the rudder, I would just follow the line shown on the plan and forget about the trim tab. The elevator looks ok as is. If it is an original kit please check the balsa carefully and replace any "suspect" material with new (I'm sure you will anyway). I would also suggest leaving the side windows open to assist with the through flow for cooling. Much neater than cutting holes in the underside of the fuselage.

Are you going to do a build log ?

[Erfolg]

Kevin, afraid not. I want to fly the model day in day out, landing on less than perfect strip, being mishandled.

I really do take the view, that if it were not for the cost, Mercury would have supplied Silk or Nylon. Today there are better materials available, in that it is easier to attach and finish, and can be as strong, robust and can look like the dogs dodahs.

I will check the balsa for suitability and also check the spar material and replace as is necessary.

Often with the original full size aircraft, provision is made for cooling the engine, as i suspect at this time it will have been air-cooled and probably a flat type, like many of the Continental engines. Ideally i would use these for cooling.

At present i do not know what I will do, although more inclined to pay at least some homage to the full size, although using the current modelling standards/state of the art methods, when advantages.

[PatMc]

Erf, here's a magazine article of one built then crashed on it's first flight due to the wing fixing. The builder recognised the reason for the failure so he repaired it with mods to prevent a recurrence. Subsequent flight was a success.

Incidentaly I've was given a Replikit "short" kit of this model as a birthday present a few years ago but haven't got a round tuit yet. My intention is also to built it as if modern gear had been available back then, reduce the dihedral install ailerons & scale size control surfaces etc. I'll definitely be changing the free flight style "lifting" section of the tailplane to a sensible flat plate one, probably 1/4" built up.
The full size aircraft was unusual in that the wings were all metal whilst the fuselage was fabric covered. I have considered covering the wings with either balsa or depron (first reducing the rib thickness to accomodate) but as yet that's not a definite.

If you want the accurate flying surface sizes you'll find them in this plan from Outerzone.

Edited By PatMc on 06/01/2016 23:09:52

[Robin Colbourne]

Whilst we are on the subject, do you think this could be a Mercury Aeronca Sedan, despite the description? The massive dihedral that 'Merco 61' described is there, and that registration number matches the one in the Mercury kit.

**LINK**

[Erfolg]

Thanks for the links Patmac, I have printed them out, for reference.

I am also totally with you with respect to adopting current RC equipment and also practices (where applicable).

I will not be adopting the amount of dihedral that the link that Robin points to. I have painful experience of my VS Tomboy, where the excessive dihedral as per plan, caused massive Dutch Rolling, when any rudder input was used. This was so bad, that the then club expert flier said the model was un-flyable. I reduced the dihedral to zero, where upon it became a pussy cat. I will check the dihedral that the full size use and hope it is zero, or very slight. I would then be able to build the wing as flat as is possible.

I have discovered yesterday that this model may have to go on the back burner for a while. I will concentrate on finishing those models presently under finishing and modification (where need for operation).

[Robin Colbourne]

There's a good article here on the Mercury Aeronca Sedan, by David Deadman in 'Flying Scale Models with lots of engine discussion and building tips.

**LINK**

Edited By Robin Colbourne on 07/01/2016 11:38:24

[Erfolg]

Robin, it is the same link that Patmac has provided. An excellent article though.

I still have not studied the plans supplied, although along with Patmac I do intend to sheet cover the wing, probably with 1/16" balsa. Although I do some building with Depron, I do not find it to be very strong at all. A bad arrival can leave shattered sheet.

[Peter Miller]

I built one in the very early 70s. It is a remarkably solid kit. I seem to rememebr I flew mine on an ED racer.

I am pretty sure that it would be happy on a .40 four stroke these days with full hose radio.

The wings were designed to knock off in crash. They would well do with major mods to the mounting and attachement.

[Erfolg]

A couple of pictures of the kit.

As yet i have not looked at it carefully, which i must, to ensure that i obtain suitable spar material, if i do not have sufficient at the moment.

I would guess circa mid 60s as the Grainger company is repeatably referenced.

[Erfolg]

I have had a few minutes today and decided to look at the wings.

It does seem that they need some modification. The spars are all wrong, plenty of depth, at what appears to be 3/8" wide but little width 1/8 balsa". These i will change to spruce or similar 1/8" thick and probably 3/8" or 1/2" dependant on what I can get. I will also put in some hear webs (for non engineers, the shear webs are there to keep the outer fibres where they are supposed to be, rather than crippling under compression, typically the to spar). Yet another topic for BEB for an article, perhaps.

The trailing edge seems to be 1/16" sheet material on the upper surface only, again i will probably change to a std. trailing edge stock, After skinning i will then sand it flush to the skin.

I also agree with the other observations that the a three piece wing assembly is needed with a different type of centre section. I still have some brass box and steel blade material, which I probably try to get some more, or just use what I have. The other alternative is carbon fibre or glass tube, with a aluminium inner or something along those lines.

I think a quick fastening system for the wing struts is required. As I do not like fiddling with small screws/ May be P type fasteners?

The body is altogether a different kettle of fish, the building method being most appropriate, in that it is similar to the full size. More importantly the type of construction builds into a light strong, resilient structure.

A very different build for a typical build today, where often sheet material is used with local ply facing.

It is interesting to know that Peter has built at least one.

Edited By Erfolg on 08/01/2016 16:42:31

Edited By Erfolg on 08/01/2016 16:43:25

[PatMc]

The plan on Outerzone shows the wing TE as 1/32 " top & bottom. I not sure if the Replikit one I have is the same (I'd have to dig it out to check) but I suspect it is, as credit for the one on OZ is given to Vintage1 who I think prepared all the plans at Replikit.
Unfortunately he had a bee in his bonnet about the reducing the wing incidence in a lot vintage plans which IMO was completely misplaced. I don't know whether or not he altered it on the Sedan plan.

I also intend to use a brass box with steel wing wing joiner system, tying it to a different mainspar setup. Probably use a short piano wire in brass tube for the incidence keeper. It will still be a two piece wing plugging into the cabin top. The fuselage formers will all be cut from 3/16" birch ply.

[Erfolg]

Patmac

I have been reading the small instruction book that accompanies the kit, it also has a sheet, underneath.

I have in the past built a wing in this manner in the past, with the open end closed of with sheet, similar to a shear web. I built the wing in this manner to avoid distortion, with the believe that all the forces in the bits and pieces would cancel themselves out, leading to a warp resistant TE. When i returned to aeromodelling this was the one wing that was badly warped. requiring the TE region to be totally rebuilt.

It seems that the simpler the better.

At present I have not got to grips with the design as you have Patmac.

I tend to follow the build /design approach of PM and probably others, that simple. engineered structures work the best. Just observing our environment, particularly Victorian structures and dock yard cranes etc, are a lesson on structural design. You just have to think why have they done that.

[PatMc]

Erf, I've used the same type TE construction on many models going back to the 1950's, can't say it's ever been a problem though I would normaly incorporate a shear web in it at the front of the "V" even if not in the design when I'm building from a plan or kit. I've always found it a little lighter than solid TE stock, less prone to warps & just as easy to make.

IIRC a KK Stunt Queen was the first model I built with this type of TE some time around 1956.

[Erfolg]

Patmac

We were discussing the kit at the field today.

I was saying how surprised, perhaps disappointed in the design of the structure of the wing, which appeared to be at odds with the body design.

It was pointed out that in the era that the kit was current, most models would be free flight, not seeing the flying loads that a modern RC model would typically see. even when flown conservatively. The model most of the time, taking lazy circles as trimmed, driftting with the wind, at probably no more than 50 feet up. The landings being uncontrolled at the mercy of God.

Even when flow RC in the 50s, the RC being more of a trimming aid, to keep the model in the field, than for the degree of control that is typical today. This puts the very small rudder into context.

It then struck me the structure is probably more about ensuring the wing remained true at low weight than for structural purposes.

On the general assessment the initial designer will have fulfilled his brief.

This does indicate that the redesign of both the wing structure and fastening can be done with a clear conscience and is necessary (as your link suggests).

Edited By Erfolg on 09/01/2016 15:28:48

Edited By Erfolg on 09/01/2016 15:29:48

[PatMc]

Erf, I think that the Sedan was designed purely for F/F, it being up to the builder if he wanted to adapt it for R/C (S/C only back in 1952 when the kit was launched). If you take a close look at the rudder shown on the plan you'll note that it's actualy inset within the scale rudder. The scale rudder isn't moveable & no elevators or ailerons are shown.

As a F/F model the wings would be intended to spring loose in a heavy landing/crash without causing damage to the fuselage. Also they'd be designed as light as possible for the same reason & for their own survival.

[Erfolg]

It seems that we both agree that the original wing design was intended to have features that are not entirely desirable or optimised for a RC model.

On that basis I now have not a single qualm modifying/redesign the wing for RC work.

It is also reassuring that wing was not poorly designed, particularly in an era that the UK still had a significant engineering base. I just could not reconcile the apparent conflict of the design with full size examples of good design for structures, dating back to the early Victorian era, to the then era. It seems it all comes down what it is you are trying to achieve.

[Area 51]

PatMc my dear chap.. Can you tell me what you drop the wing incidence by or too?

I have the sedan and am wanting to add ailerons when I re engine to an Os30 4 stroke..

Thanks in advance, as always!