Mercury Models Aeronca Sedan conversion to RC and electric?

[Peter Smith 12]

Skulking around in my loft I have a very old 90% finished 60" span Aeronca Sedan built from a kit by Mercury models. It was originally intended as a free flight model for use with ~1.5 - 2.5cc IC engines with 11 x 5 or 10 x 5 props.. With the "summer" weather the way it is (!) I'd like use the time to convert it to radio with elevators, ailerons, rudder and throttle, plus put a brushless motor in it. Not wishing to re-invent the wheel I wonder if anyone on the forum has done this conversion? The radio installation should be no problem as there is ample space but I'm particularly interested in what brushless motor and prop size was used? The are one or two items about it on the Web but nothing too detailed.

[Tom Wright 2]

Peter depending on the weight this type of model would fly well on a 900-1100 kv motor rated at 250-350 Watts .If you are not to familiar with EP check the BRC web shop and have a look at motor specs and come back to the thread if you have more questions .

Tom.

Edited By Tom Wright 2 on 03/07/2012 16:06:46

[Peter Smith 12]

Posted by Tom Wright 2 on 03/07/2012 16:04:31:

Peter depending on the weight this type of model would fly well on a 900-1100 kv motor rated at 250-350 Watts .If you are not to familiar with EP check the BRC web shop and have a look at motor specs and come back to the thread if you have more questions .

Tom.

Edited By Tom Wright 2 on 03/07/2012 16:06:46

Thanks for that. With a prop size of..............?

[kc]

A fellow club member has electrified this model. He reduced the dihedral in order to fit ailerons . It seems a very practical electric conversion. I think he will reply with further details.

[Peter Smith 12]

Posted by kc on 03/07/2012 16:26:04:

A fellow club member has electrified this model. He reduced the dihedral in order to fit ailerons . It seems a very practical electric conversion. I think he will reply with further details.

Oh thats good news indeed. Thanks

[Wasaforumite]

I would be interested to hear any tips on electrifying this plane. Its my next project having bought the plans. I believe the wing mounting and u/c will need strengthening to cope with the additional weight/power of the electric conversion. Ian

[kc]

Ian. Is it the Mercury Models version? Normally this was only available as kit as far as I know and long since discontinued. Can we still buy a Mercury Aeronca Sedan plan now? Or are you building a different version?

I have not got exact detials of my friends Sedan but I think it was built as original Mercury kit many years ago and modified for electric by simply replacing diesel with an Overlander brushless motor and 3S 2200 Lipo. I cannot see why the weight would have increased so probably no strengthening was done. I saw the model fly last Thursday and I must say it flew beautifully.  It had 2 seperate wing panels & normal piano wire wing joiners I think. Certainly it had functioning wing struts. Wing panels are held in place by rubber bands through the centre section ( not over)

Recently the dihedral was reduced to very little and small ailerons fitted out near wing tips. ( ailerons in the 'barndoor' position but rather narrow like strip ailerons) I was told that ailerons were not particularly effective and it turned just as well with rudder despite the lack of dihedral. It seems coupled ailerons and rudder are needed.

I will try to get more exact details if anyone needs them.

Edited By kc on 26/08/2012 15:02:42

[Mark Powell 2]

It's the Mercury Models one - it is in the thread title and the OPs first post, where he also mentions the Mercury kit in his attic.

The plan is supposedly available from Colin Smith, Phil Smith's (the designer) son, but contact details are a little hard to find.

I scaled mine up from the AMI (a couple of years ago) print of Phil Smith's plan in the magazine. It is a pretty simple thing to do, with a compass, rule, and a pair of dividers. Mine is partway built but put aside for the moment..

Ailerons. I am reducing the dihedral slightly and getting the aileron shape from the 'fullsize' article in the same magazine. You don't need CAR, it messes up everything except 'gentle turns'. Just 'co-ordinate the controls' when flying it. A little aileron differential will help. to make the ailerons more effective.

For the 'purist' the merge of the fuselage rear top and the wing TE is totally wrong. The rear fuselage top  should continue on forward a little over the wing, not end 'flat' at the TE.  Thus the top should be little higher than the plan shows. Plenty of pictures of the real ones on the internet

Axi 2820/10 motor on 3 cells will be fine for pottering around, which is all the real one ever did.  Don't overpower it, lowish power makes you do the takeoffs properly. It does on my Auster! Use a 40 amp controller 2200 Lipos are a bit small for a model and motor of this sise, the duration will be a bit short. I would go for 3000 at least. (or an OS 30 four stroke, Which I'm using!)

Edited By Mark Powell 2 on 26/08/2012 16:28:05

Edited By Mark Powell 2 on 26/08/2012 16:29:23

Edited By Mark Powell 2 on 26/08/2012 16:35:17

Edited By Mark Powell 2 on 26/08/2012 16:44:29

[Guest]

plans for Mercury,Keilkraft,Veron and other similar kits available from Phil Smith's son, Colin at

[email protected]

Phil did offer to scale plans up or down and I assume Colin offers same. Also used to include copy of original kit instructions and templates for formers and ribs etc. Check with Colin

john

[PatMc]

There's also a short kit of the Sedan available from Replikit.

I was given one as a birthday present some time ago but haven't got around to building it yet. One thing I will change is the tailplane aerofoil. On the plan it has a lifting section, mine will be flat plate - probably 1/4".

Edited By PatMc on 26/08/2012 20:52:38

[Wasaforumite]

Thank you all for your observations on this fine design. Yes it is the Mercury design and I did obtain it legitimately from Colin Smith. The plan is excellent although requires some studying before embarking on construction. The wings are simple enough but the fuselage is more complex. Having already got the plan I will take my time and cut the parts out myself but having a part kit does have its attractions.

Installing ailerons is desirable mainly because it enables the dihedral to be reduced leading to a more scale like appearance. I don't suppose it will have a great effect on performance as this classic design is essentially for pottering round the sky using a small engine. Having ailerons also does away with the need to (re)learn flying on rudder and elevator. If its aerobatics you want, I could suggest building from a suitable Citabria plan instead as I am sure you would need more power and a stronger airframe.

The idea of having an airfoil tailplane is to provide tail lift in proportion to speed thereby lessening the effects of climbing under power. Reverting to a flat plate tailplane may increase the need for downthrust.

I am still concerned about the wing mounting, as in his article the late Dave Deadman describes how the wings folded on his beautiful model on its first flight when they pulled out of their mount on the fuselage. For those of you who haven't read it the link is here:

**LINK**s

Perhaps the mounts just need a little extra strengthening? Perhaps those who have actually flown one of these can comment please?

Thanks

Ian

[PatMc]

Posted by Ian Heath on 26/08/2012 22:15:00:

The idea of having an airfoil tailplane is to provide tail lift in proportion to speed thereby lessening the effects of climbing under power. Reverting to a flat plate tailplane may increase the need for downthrust.

Judicious elevator used with the throttle will take care of that.

[Mark Powell 2]

The real one has a flat plate tailplane made out of welded steel tube, also wires from the tailpane to high up on the fin and the bottom of the fuselage. Mine has a sectioned tailplane because of the aerodynamic effects you state  (if you believe Bernoulli and not Newton, I go for Newton but curve it just in case) and because it looks nicer. Can't be bothered with the wires.

The 'more than scale' wing incidence on free flight models is the cause of the problem. I always reduce it on radio conversions, even on my Junior 60. You can compensate with elevator but it is a pain, and doing it with a throttle to elevator mixer can produce rather sudden 'bad effects' (five foot up, then one foot up and nose down) at low landing speeds when you wham the throttle open when your landing is baulked. New Forest ponies, in my case.

Mine has a one piece wing, the struts are just decorative. Makes it all much simpler.

If you have a two piece wing the free flight method is usually hopeless. My Airsail kit Auster has that and making a one piece wing is difficult because of the all glass cockpit. The Airsail wing/strut design is also hopeless, even though a quite heavy r/c design, so I changed it.. I used a very strong steel tension spring beteen two hooks. Your struts have to be good too. there can be unintended negative G sometmes and the fixing have to be secure even if the G is only positive. And the sruts stiff. My fixing is brass plates firmly attached to the main spar and to the fuselage. and the fuselage plates are carried throgh to its opposite number as it is all one piece. The struts are bolted on, none of this Kwiklink stuff. As for the struts they are the hollow airfoil section aluminium tube, stiffened with a 1/4 inch carbon rod (not tube) epoxied in. As I dont trust joining end fittings to carbon, at the same time I epoxied in a continuios 14 guage wire with loops on each end for the strut fixing bolts. Ten years old, with the occasional outside loop (on an AOP 9?)and nothing has broken yet

Aerobatics on a high wing plane. Build the Sig Citabria. It is excellent for what it is.

Dave Deadman's article was my original inspiration and that is what I scaled up the plans from. All the magazines used to have scaleable plans. They even made it an easy 'fractional' scale and told you what it was so you could do it. Not so 'commercial' then..

Edited By Mark Powell 2 on 27/08/2012 06:09:29

[David Davis]

One was flown at our club's Vintage Day. The builder had fitted an OS fourstroke and modified the wings for ailerons.