Aeronca Sedan

[Erfolg]

Hmm, I think we see models differently. I am not particularly into vintage kits, in being special in themselves. I just happen to have some old kits, mainly as a consequence of not having built them. I often see both kits and plans as a starting point, some do not benefit from mods, many do.

I do like scale models, although I have never got to hung up on speeds that are seen as scale by some definitions. I see all my models, particularly scale as facsimiles that moved from place to place. I do baulk at model Spitfires that are obviously going very fast.

The trouble with a lot of early kits, circa 50-60s is that the wings of many seem to be very poorly designed. Particularly the Sedan, in that in bending or torsion somewhat lacking. The loose dowel arrangement at the roots are an accident waiting to happen. The security of the wing appears to be dependent on the strut, both in maintaining the pegs in the body and also performing as a structural member. As a SC radio model, I would have hoped that the peg arrangement would have modified back in the day, to at least improve location.

In principal I would be looking to build a wing that performs as a simple cantilever, not seeking any structural benefit from the strut, in essence a redundant member, other than aesthetics. Sheeting the wing serves two objectives, it increases the "I" value etc, as well being nearer to scale. The wing section of the kit, is a long way from being a representation of being scale, although functional as FF, many other currently used sections on RC models being nearer to scale and having a drag bucket that improves versatility for RC models.

Then again we see nostalgia differently every one of us, mostly my nostalgia is about remembering the time, as I lived it, I dwell on what I perceive as the good. For me the past was not all good, rationed food, parents working long hours, many ordinary things being expensive, I can get quite emotional about some aspects , not in a good way.

Perhaps these things define what I want from a model, it has to function as everyday RC model, flown as any scale model (that it is it moves under control from point to point), using effectively the current equipment that I use as effectively as possible.

[Peter Miller]

Peter, a number of people have said at the club, it is a pity that your Cassut (that is your design electrified)is so small, at twice the size it would be great. Again because it flies and looks really well.

Well the Cassutt can be enlarged.

Another of my Cassutt types is called Miss Cassy which is published by ADH Publishing. Oy is powered by a .25 engine.

[Erfolg]

Peter

I have had a change of plan, your reference to your other modellers started a chain of thoughts. What is it many people like about the Cassuts (Miss Demeanour)? I came to the think it is the simplicity of the form, it is similar to a latter day Chief Oshkosh, (which I have toyed with and thankfully given the handling issues of the recent one in RCM&E. I remember vaguely when studying, that the lecturer made the point that in fast flying aircraft (well away from the stall) that a rectangular wing is as good as any, That much of the tapering in modern aircraft is more to do with structural issues than aerodynamic imperatives. The body is similar in that the shape is essentially simple. Same lecturer made the point that much of the wing fillets on many aircraft, is due to the undercutting from an oval or round body. Make the junction square and many of the issues are minimised. It is strange how much of the fluidics lectures, particularly the formula have been long forgotten. Yet passing comments on side issues are remembered, even the smooth and rough balls dropping through a glycerine filled glass beaker.

After some deliberation my attention has now turned to your Vans 3, at 48" span.

Part of the problem with the Cassutt is I used to fly at a glider, electric club. There was no issue of flying close in, ensuring the model never being far away. The reasons I guess are that in competition, gliders are frequently flown towards the flier, to the landing circle. In the case of small, light weight, low powered electric models, necessity means they cannot be sensibly flown at distance and the consequence of striking you are low compared to a 100cc monster. Since then I have moved to a power club,  having moved I joined another power club with a lot of LM. Close in flying is a no-no, big regulated circuits are the order of the day. The Cassut at 33", quickly becomes an issue as to what it is doing, relative to what you think it should be doing, even when quite close.

I realised whilst in bed I made a major mistake, I should have recognised that when flying up wind the minimum speed is the Stalling speed- head wind + 5-10 mph safety margin.

The difference between a FF model and RC model in flight kept me thinking. When I was much, much younger my interest was Slalom Canoeing. Maybe surprisingly there are many similarities. Just like RC flying, you canoe relative to a fixed point, gates, not the flow of water. You quickly realise that entering the moving stream from a slower moving body, requires a lot of corrective actions requiring both power, adjusting the boat hull and paddling (down stream, leaning on the paddle). It is similar when entering the downstream moving body, you need to accelerate to have any control. When your 2-3 minutes of exertion are over and you are now drifting down stream, with the water, the boat does not care how you move about in it, lazy circles, sideways, backwards, just like FF. If you want control, it is altogether a different ball game, In the real world of small relative area, that the school boy, vector questions of cars, yacht or airlplanes have little to do with RC models and Slalom canoes.

 

Edited By Erfolg on 19/01/2018 12:40:27

[Erfolg]

At first I thought I disagreed with you Patmac, then reading the further comments I found that we are possibly thinking along similar lines.

I am absolutely confident that a change of section does have benefits, potentially. I just remember at the time when the kit was at its greatest popularity, that most would fly it free flight. Typically the models were flown at moderate to slow speed. A section where the drag increased at a high rate as speed increased was desirable, to keep that speed down. The section ideally would have benign stall characteristics. Much of this was achieved by a high camber and a very well rounded LE.

Looking at the wings structure it is apparent, that it was desirable that the wing would readily part company with the body on any arrival. It is also very lightly built, possibly on the basis it would not see much in the way of bending forces or shear stresses.

I have also noted that the AoA between the wing and tailplane is very large, by RC standards. Many RC models adopting a 0-0 alignment. This will also have to be addressed.

Being a glider guider for much of my RC adventure, I was obsessive about wing sections. I experimented by building multiple wings. I found high camber, particularly the under cambered lower surface, were OK with no wind, where you just hovered going nowhere, when the wind picked up and you tried to move, to penetrate to perhaps better air, you just came down vertically, almost. The very last recent comparison i built (on returning to RC) I found a light weight Clark Y was poor compared to HM32, the differences coming down to thickness and camber.

Again towline or winch launching needed a bullet proof spar arrangement. That the weight was not much of an issue, compared to the additional height that a Gorilla towman could get you. The V^2 in the drag formula took care of the issue and you wanting to travel from sink to lift (hopefully). Hollow glass wings are both light, stronger and more accurate, than any of my wings (still have a collection).

So I decided to redesign it, a bit of an overstatement really.

I decided initially with plug in wings.

I dug out a selection of my remaining bits and pieces, from Hinderminium Aluminium tubes, Carbon fibre, Brass box and steel blade and finally brass tube and piano wire. In the end i decided a one piece wing will be better, as it is only about 5 foot span. I would also bolt the wing on, with front dowels.

Today a model must have ailerons, so it will incorporate them.

The wing also is designed pragmatically around that I have, so spruce spars, rather than the Glass Tow spars, an example is in the above photo. To much fuss, I have miles of Glass Tow, but no longer a press to consolidate the lay up, although still tempted.

I continued my deliberations with respect to wing section, finally deciding on Clark Y, the camber is less than NACA 4412. It is a little chunky, although it works well on power models, where the it being a little more peaky than E205 is not such an issue, reasonable drag bucket at speed, has a more rounded LE than E205 so stalling is not as sudden (even though E205 is good).

You can visually see the raised stagnation point or the 0 point compared to NACA 4412 and particularly the kit section.

I have also decided to sheet the whole wing as per full size, as it is convenient and helps with stress distribution as well. Belt and Braces approach, excepting something will always break come to the crunch.

[Peter Miller]

The Aeronca Sedan kit was a free flight model. IT was never designed as a radio control model.

[Erfolg]

Peter I do not disagree, that is why to use it as a RC model, there needs to be changes.

The lifting tail will become symmetrical, the Cg will be moved forward.

As a kit it is no use as a historical artifact, is it not better to make some use of it? I probably could sell it for a tidy sum, where it will languish on a shelf, with a pile of other unbuilt kits, until the new owner dies, where upon the executor of the estate will either sell on again, or consign it and the other detritus of early times to the tip.

I hope no one thinks I have an issue with the design for what it was designed to do. Unfortunately those times and spaces have passed and the space is no longer available. It is sad that all of what were my local sites/fields are now built on. Even the land adjoining the Mersey (upper) now is full of small holdings and a water park, once seen as unsuitable for anything other than a few cows and some meadows.

[Erfolg]

Having received feed back that some believe that the kit should be built as it is or just saved, that is stored, I decided that in view of the significant amount of work or differences to fly the model as a current RC model, in deference to others sensibilities, I would just stick it away.

I then got out my wallpaper and pencil, and redrew it for current use.

which means a new front end, rearranging the wing to tailplane incidence, tailplane, rudder, undercarriage and a new sheeted aileron wing. Although it looks the same, it is now very different.

As all the various kits, the body follows the same general formula of a box section with bits stuck on to provide a shape. Just like the full size.

Just stick in a few formers.

Then stick on the others side.

Stick the body in a jig, then add all the cross members.

Now this bit fooled me. I stuck in a doubler, then sheeted as per all the various kits. It is only later i have discovered that the front end of the full size was not ply covered, it was just canvass.

Now a few formers and stringers have been stuck on. the all important Lipo and motor box have been installed at 90 degrees with no down thrust.

I have a few more pictures to post tomorrow, as to where the project currently stands.

[Richard Clark 2]

Posted by Erfolg on 10/06/2020 16:33:15:

Having received feed back that some believe that the kit should be built as it is or just saved, that is stored, I decided that in view of the significant amount of work or differences to fly the model as a current RC model, in deference to others sensibilities, I would just stick it away.

I then got out my wallpaper and pencil, and redrew it for current use.

which means a new front end, rearranging the wing to tailplane incidence, tailplane, rudder, undercarriage and a new sheeted aileron wing. Although it looks the same, it is now very different.

As all the various kits, the body follows the same general formula of a box section with bits stuck on to provide a shape. Just like the full size.

Just stick in a few formers.

Then stick on the others side.

Stick the body in a jig, then add all the cross members.

Now this bit fooled me. I stuck in a doubler, then sheeted as per all the various kits. It is only later i have discovered that the front end of the full size was not ply covered, it was just canvass.

Now a few formers and stringers have been stuck on. the all important Lipo and motor box have been installed at 90 degrees with no down thrust.

I have a few more pictures to post tomorrow, as to where the project currently stands.

 

You are doing fine. A couple of points:

1) Later on you will have the side window surrounds to do from 1/16th sheet, as in the Mercury kit. I cut two out, window holes included, each from one piece of sheet, and two more exactly the same from 0.8mm ply.

I checked that they matched exactly and then enlarged the window holes in the BALSA ones by about 3/32 all round. Then I stuck a balsa one and a ply one together, making a left and a right one with the ply on the outside, so the balsa ones form an 'inner recessed rim'.

Then I cut the four windows from transparent plastic sheet to the 'inner rim' size and stuck them in from the INSIDE. Only then did I glue these panels in place. It all ended up very neat and avoids unevenness if you glue the plastic outside. (Most reall planes have a slight recess where the windows are.)

2) When it's all done, including sheeting the fuselage underside, don't forget to fair the sheeting to the longerons with about a 2 inch x 1/16 x 3/16 balsa piece roughly sanded to a 'wedge' and finished off after fitting, at each of the longeron places, as in the Mercury kit. 

Edited By Richard Clark 2 on 10/06/2020 20:36:50

[Erfolg]

The build goes on

The under stringers went in, with a removable bit for the UC.

The bits at the end have been made. The tailplane is non lifting. Also the there are surfaces that will be linked to the servos, not a big deal, although different.

I have introduced a platform for the tail assembly when it happens. I am surprised that the Mercury arrangement lasted more than one flight. I considered using bracing wires as the full size. To keep it robust, the forces required in the wires and surrounding mounting faces would be to high for my liking, also the turnbuckles etc, just to fiddly for this (ex) battleship engineer.

This is all for a little while now, as I turn my attention to the wing and cowl.

[Erfolg]

Although I stated that there would be no more posts until I had made the wings, or at least some progress, you can see that is not true.

I had intended making a cowl much later. That was when I had decided how to go about making one. In a way I have decided how to go about the challenge, as that is how I tend to see, inline cowls. I had considered a balsa nose area, with the sides being a mixture of block and planking. I turned against this approach, as I could not see with any certainty i my minds eye, what would be done as as series of bits. Plus when I do these things they consume vast quanties of block and sheet.

In recent years I have increasingly used Blue Foam, for block work type tasks. Yes, that is how I will approach this job. The intention is to have Blue Foam nose, side panels. The underside will have a piece of balsa sheet. The top panel will be mainly a bent piece of sheet. I will build it as one, then separates into two pieces. A top hatch for the Lipo and arming, the nose, side pieces and undersurface. The nose will also be removable, by removing screws, this is for the motor installation and maintenance.

The whole lot will be glassed to impart ding resistance.

It is worth noting that many of the close ups of the full size cowl, show a less than perfect fit of sheet metal. On the other hand, a lot of the aircraft at the various meets, have perfect cowls, some having replaced the original cowl with a fibreglass moulding, the cowl and the rest of the aircraft being far better finished than the original factory build. The original aircraft was built to a low price.

I now have to wait for te temporary spacers and white glue to dry, having made reasonably sure that the nose CL is inline and level with the various datums.

The next bits will be done over a period, whilst I get on with the wings

[Erfolg]

Whilst we are thinking about what happens next, I would like to direct you to a site that Mick Cripps has found

The first bit that is really interesting is Publications then from the home page, there is so much MORE.

[PatMc]

Post deleted.

Edited By PatMc on 12/06/2020 22:55:26

[Erfolg]

Patmac, I think there has been an misunderstanding, all the links you have provided have been followed by me and are much appreciated. I do hope that you will continue in supporting my efforts.

I probably have been guilty in not acknowledging the individual help received.

I must also appologise to Mr Cripps as his name is Nick, rather than Mick (I thought perhaps short for Michael)

This particular model has been of the most problematic of my builds. I have come to generally accept that I can buy at least one book, with a history, including the initial design, concept drawings, the persons involved and often pictures from various eras. In this case, I only fond the one book on Amazon and Albis, both of which were to rich for my pocket, from memory circa +£100 (second hand).

I have the one thumb nail drawing, which is obviously erroneous with respect to flaps. The rest of my drawings are a derivative of a Mercury, Berekley and Pica drawings. Yet I still have got some aspects wrong.

Edited By Erfolg on 15/06/2020 12:04:29

Edited By Erfolg on 15/06/2020 12:05:25

[Erfolg]

I did say i was going to work on the wings. Hmmm, as frequently happens i have not.

I have been struggling with the cowl area. Lots of hangar rash, and it still needs lots of extra work.

I invaribly end up with tail heavy models, even with the Lipo In-front of the prop, I need lead, in genera, that is. On that basis I want to be able to remove the cowl, to insert lead under the battery box, This has lead to loads of problems. Much to my surprise, the model already seems unnecessarily nose heavy. On that basis much of my efforts will be wasted. On that basis until I am confident, that I will not need lead, I will not glass the nose with glass cloth and epoxy, as I may need, or benefit from permeantly attaching the side and underside pieces, Just having a removable nose as on my 1/4 Cassutt,

As you can see I have managed to get two thing wrong with the nose. The first is the top radius of the battery box, the second is the over-sized box for the Lipo, which has made things awkward.

I have now started on the wing area over the cabin. In the past I disliked cutting proper ply, being slow and hard work, needing a lot of sanding(when I did it). The old Dremel Jigsaw (which i have had for some time and the Aldi disc sander (recommended on this site) have made fast work of the first part, and improves accuracy and finish no end.

[Richard Clark 2]

It's coming along nicely. Good to see an entirely scratch built model.

On my Mercury one the battery is mounted low down and transversely at the C of G with a small hatch on the side. That way I can use any size battery I want or even change to glow without altering the C of G. (I used a 'quick change' method of mounting either including an enclosed glow silencer and both a throttle servo, its linkage, fuel tank, and an ESC are permanently installed.) By pure luck the glow engine with its silencer and the electric motor weigh exactly the same.)

[Erfolg]

I am finding a major problem with this particular model, which I am building from the proverbial off cuts box, is keeping the bench anything approaching tidy.

Habitually I put all the tools back to predetermined homes, the majority on my IKEA Billy book cases. Except it seems when I make some slight progress, where I find piles of tools of varies types. Saws, French Curves, set squares, sanding blocks and piles of bits of wood I have been going through, from the offcuts box.

My other issue, is that in some instances I have deviated from my drawing, and more work is then required to get back to how it should be. Then again, the various links that have been provided have shown that some of my structure is pretty beefy compared to full size. Although I am very much a it must fly well, but should bare some resemblance to scale when viewed at twenty feet whilst squinting, type of modeller, I am beset with internal, self inflicted issues as to what extent to compromise. The other issue is that my detail design follows the practices of PM and a certain Gordon Whithead "Scale Aircraft, for everyday flying", where I seek reassurance that what I have drawn is practical, robust, sympathic to the full size. At the back of my mind, is a issue, where I was less than happy with some one elses design, I let it go, latter came to regret it. Design can be both fun and a battle with your own internal demons, Hmmm, time for a whisky, whilst i contemplate what PM and Gordon would do.

Yes kits are much easier, ARTF, require no thought and almost no skill. Perhaps that is the way of the future.

[Erfolg]

As is usual, not everything goes to plan. Indeed much of what could have been planned ,has not.

I had written that I intended to start on the wing. As I laid out my plan I realised that I needed to have the central part of the wing as a starting point. On the full size this part is part of the cabin/fuz. Indeed the Mercury approach was follow pretty much full size practice, with, plug in, wings that sprung out on an arrival.

I have dithered on this area, for some time. I had decided that I needed a hatch in the cabin roof to gain access. This would allow for the mounting of servos, Rx etc. The mercury approach was a door on the right hand side (from memory), for this purpose. I was and am not enthusiastic to this approach, as a significant re-enforcement would be required to replace the lost integrity caused by the opening.

I was not keen on a hatch, as this required plug in dowels, such as used on model gliders.

You may recall that I still have a selection of joiners. From high strength aluminium, brass box and steel strip, a selection of brass tubing and piano wire inserts, and some polyester spar capping (made from glass string).

I have a few brass box type arrangements that were salvaged from a 144" fling wing that I built, with the gliding characteristics of a "lead Butterfly". Which unsurprisingly was consigned to my bin of failed projects.

I weighed the bits that immediatly came to hand, which came out at 50gram each. Without to much imagination, I realised that I was looking at +100g assembly. I have never been to impressed with the brass tube and piano wire arrangement, other than a glider on tow, could benefit from the piano wire bending at the root body interface, if over stressed, rather than some part of the wing failing. There were other permeations, which benefited from the parallel axis theorem, if bolted up solidly. All were pretty heavy, in practice, although there would not be any failure at the root.

I spent a lot of time planning to make a solid epoxy, glass tow/string joiner often seen on modern high spec gliders, something approx 12-15mm square cross section at about 300 long. Then the doubts set in.

On balance I thought, you know, this is a light, civil aircraft, at best stressed for simple aerobatics, It does not need the strength of a tow line glider or a aerobatic model, that will do a Lomcovac type manoeuvre.

On that basis I have decided to run the spars into the cabin to area, and just rely on ply bracing and shear webs on the rest of the wing. I will put enough (I hope) material in the cabin to area to resist any crushing tendencies. This will now be a one piece wing. At 58" span in this era not big.

So what has taken me so long to do apparently nothing? Well, I am slow, plus most of the area is ply, needing a lot of sanding. Ah, yes, that indecision.

Just about ready to start what I intended doing about a week back.

I am still on track, relying mostly on my bits boxes.

Edited By Erfolg on 02/07/2020 15:03:18

[Erfolg]

Right, then. I have started on the wing, still quite a bit to do.

I have made a number of errors, which I have fudged. Plus some deviation from the drawing I have done.

At least it fits, quite well, it seems.

I have struggled to keep the work surfaces tidy and debris free. That is my next job before moving on, to the servo hatches, a few bits for the hinges to fasten into, plus the wing strut re-enforcement.

Then my attention will turn to the UC. and finishing the motor cowling.

[Erfolg]

A little more progress has been made. That is after a number of cock ups, which I have struggled to bodge. Being a philistine, that is what I have done. The craftsman would have undertaken a far more fundemental rebuild of the affected areas.

[Erfolg]

This morning I thought that at last I had the wing finished to at least 90%. Returning indoors with the wing, I felt then saw another issue, which i started the process of rectifying. Then I found yet another, which needs dealing with. Will I ever finish the wing.

I was threatening to turn my attention to the cowl. I had tacked it on, for the shaping process. It is such a long time back, I cannot remember with any certainty of where. I then vaguely remembered why there is an apparent slot in the top of the cowl.

When the weather turns for the worst I will return to the cowl, in the mean time I am going out flying (this afternoon), I have watered the flowers this morning, so that is done.

I will be looking for constructive advice in how to secure the tail unit, as even with the faired plate (non scale) I have introduced, this area is pretty weak. I have been thinking along the lines of CF bracing, glued in position, to mimic wire bracing wires. The issue is ther is not a hobby shop within 70 mile radius as far as I am aware. To send away for a couple of pieces would make the PO richer, for the price of a few quid of CF

[PatMc]

Posted by Erfolg on 31/07/2020 11:18:00:

I have been thinking along the lines of CF bracing, glued in position, to mimic wire bracing wires. The issue is ther is not a hobby shop within 70 mile radius as far as I am aware. To send away for a couple of pieces would make the PO richer, for the price of a few quid of CF

Any kite specialist shops near you ?

[Erfolg]

Not that I aware off. I will Goggle just in case.

We normally do have kite festival though, once a year, probably in August or September. I guess that will be cancelled along with the Lytham Festival (we have had Tom Jones, Kylie etc ).

Unfortunately we are at the end of the road to no where, other than for the several hundred people on the Green, in the local pub and on the beach today. Worrying, as people from many areas of the NW have been told not to make journeys that are not essential. We could become yet another part of the hot spots.

[Bob Cotsford]

Anglers seem to use some model friendly materials Erf, maybe some kevlar 'wires' for bracing the tail. Or actual wires using nylon covered stainless fishing trace as I've used on a few models?

[Richard Clark 2]

Posted by Bob Cotsford on 31/07/2020 22:35:04:

Anglers seem to use some model friendly materials Erf, maybe some kevlar 'wires' for bracing the tail. Or actual wires using nylon covered stainless fishing trace as I've used on a few models?

Yes. The tail on the Mercury Aeronca is very wobbly. It was designed as a free flight model and had a 'knock off' tail. In addition the real Aeronca and thus the model has a very narrow tail seating. On the real one the tailplane is wire braced to near the top of the fin and the bottom of the fuselage.

I glued the tailplane on and replicated the bracing with Kevlar fishing line and it's fine. Though the much cheaper 'Dacron' would be just as good...

[Peter Miller]

I used 20lb nylon covered fishing trace which comes complete with crimps for the rigging on my Chaos.

**LINK**

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