Aeromaster

[Nigel R]

I'm going for parallel incidence between the wings. I've seen lots of variations on lots of plans, including different wing sections on both wings and different incidences on both wings and my conclusion is as long as they're within a degree or so it probably makes very little difference (unless you're flying F3A competition and actually good enough pilot to notice these tiny differences).

Last night and early this morning I got the ply wing beds attached:

Apologies for terrible photo composition. Try to ignore the large cardboard box!

I first beefed up my wing tip jigs, by actually gluing them together and replacing the pins with toothpicks. Then got both wings in position and slid one of the ply strips in place. The balsa wedges were cyano'd in place to hold the ply in the right curve. Then the top wing was removed and the model flipped upside down and "an amount" of epoxy was used to hold the ply to the cabane (see photo).

Top wing back on, and repeat above process for next ply strip.

Next session I will dig out the balsa wedges and finish the epoxy fill.

Edited By Nigel R on 14/08/2020 12:00:31

[Tosh McCaber]

The thread's become so long, I can't remember whether anyone's powering their AM by electricity. I'm intersted to see what electrical set-up would be required- motor, esc, battery sizes?

Thanks!

[Trevor]

I’d be interested in a recap on this too. I’ve just ordered the bits and pieces to build an electric version this winter. Whilst I’m happy to share my plans, obviously I can’t yet say how well my setup will work!

On a different subject, I’m trying to locate a commercial carbon fibre undercarriage for the Aeromaster. At the moment the nearest on offer is the CCU12 from Carbon Copy. It’s a bit tall, which could be accommodated by recessing the mounting plate somewhat. However the track is also some 60mm wider (30mm each side) and, whilst I can’t see that being a problem from an operational point of view, I was wondering what it might do to the aesthetics of this classic design?

Views on either topic would be very welcome.

Trevor

[Martin McIntosh]

Don`t know if you have yet cut the actual wing tips but I made mine a bit thicker than the 3/32nd shown on the plan.

Some neat soldering there I notice.

Tosh, if my motor produces say 2 bhp then you would need a set up which draws about 80A on 5s. Why electrify a 1966 design anyway? From my experience of trying various models on both i/c and electric then i/c wins by a mile. The electric versions just would not track the same and seemed to have a mind of their own. Let`s not start a debate on this on the thread here though.

[Trevor]

Martin, as you say, let’s agree to skirt around the quicksand of an i.c. vs. Electric debate! As a long time electric flyer (I haven’t flown i.c. since my schoolboy control line days - apart from an occasional go on someone else’s!), I’ve often pondered on this common observation by i.c. flyers that electric models don’t seem to fly in quite the same way.

Whilst there are some differences in power delivery (i.c. delivers more power as the model accelerates whereas electric delivers less), I wonder whether the major factor is in fact weight?

For example, back in the days of NiCd batteries and Ferrite ‘can’ motors I built a 58” Boeing Stearman. Because of the heavy batteries and limited power available, I worked really hard at weight saving and the model came in at 6lb 8oz. It flew well for a scale model but certainly didn’t have the sort of performance you’d want from, say, an Aeromaster. Fast forward a couple of decades and the Stearman, now with a brushless motor and LiPo batteries, weighs in at just 5lb 4oz. There’s lots more power available and performance is now limited mainly by respect for the ageing airframe. At times though, I do feel that it can wander around a bit more than it used to - a combination of less weight and probably me flying it a bit more slowly perhaps?

Anyway, the Aeromaster is a smaller model than the Stearman so, although I certainly wouldn’t indulge in the more extreme weight saving measures I did back then, I’d still expect to come out at an all up weight between 5lb 8oz and 6lb. I’d aim to fly this on a 4s x 3300mah or 3s x 4000mah battery, depending on how the cg worked out. I can’t recall what weight yours came out at but I had the impression that it might have been somewhat heavier? Does any of this ring true to you?

Trevor

[Martin McIntosh]

Well, mine is 3.5kg, or 7 3/4lbs including 2oz of lead in the tail end to counter the rather heavy Laser 80. The extra wing servos account for next to nothing and the wood was very carefully selected to be as light as possible, also any ply or blocks which I considered unnecessary were omitted. I must admit that it is rather heavier than anticipated so maybe my luggage scales are telling me porkies but they say that my 1/4 scale Stampe is only 6.2kg which is very much on the light side.

If it was electric it would require much more voltage and battery capacity for the same power and flight time than you quoted. The AUW would probably be the same in order to get the correct cg.

[Nigel R]

Trevor

I guess I would look at about 900w for this beastie. Possibly a touch more. I'm mainly going on what I'd consider equivalent to say an 50 to 55 two stroke glow. Biplane are off course quite draggy so will need a fair bit. I find 450w is enough but certainly not excessive on the smaller, 4lb bi-fly 36". That's a near direct copy of the aero master at reduced size.

Martin

I've built my tips. I cut a thin core and sheeted completely with 1/16. I figured rigging would be a country mile easier if I left them off until it was done.

[Nigel R]

Trevor that undercarriage change wouldn't even be on my radar....

Anyway. Some more small jobs, they all seem to be small at this stage now... Finished adding resin on the cabanes

Looking better than I expected it to.

Also, exhaust is finalised to:

[Trevor]

Martin, Nigel, Thanks for the informative responses. I've just noticed a typo in my earlier post - both battery sizes I'm contemplating are 4s. The Stearman uses 4s x 3300mah and has enough duration but I do have two pairs of higher capacity 4s packs that don't get a lot of use (they're used in pairs in a BT Thunderbolt), so would quite like to use these if they don't pose any balance issues. Of course the whole issue of battery location and access is another topic that will raise its head quite early in the build!

The version of the plan I'm looking at at the moment is the Super Aeromaster. I don't plan to do the quasi-radial front end but was attracted by the different cabane/wing fixing method whereby the wing is attached to transverse cabane members. It does entail a couple of heavy, grooved, beech blocks in the wings though which doesn't exactly get the weight budget off on the right foot!

[Martin McIntosh]

Trevor, have look at my pics and you will see that there are no blocks on the model. The wing underside has some lite ply underneath with 1/16th birch on top for the four wing bolts. Once a test flight was done I permanently fixed the stitching in place with RCM glue with the wings bolted on (tape and Vaseline of course).

[Trevor]

Thanks for the reminder Martin. I must admit that having the bolts accessible from the top has a lot of appeal!

[Nigel R]

Trevor you could go for a cabane structure like the Bi fly uses. It minimises the amount of wire. There is a Single central connection to top wing with functional outboard struts. It is not too onerous to assemble at the patch.

[Nigel R]

[Nigel R]

There she is - finally! A lot of time sunk into rigging the cabane structure and top wing attachment. Everything has come out nice and level, but it took some work to correct a few early mistakes - I really needed to do a better job of jigging when I put the cabanes together in the first place.

A few small tidy up jobs left to do, but essentially woodwork complete and ready for covering... at which point I will have to put the build aside as the tatty old garden shed in which my "workshop" lives, is being demolished, and a replacement must be built

[Trevor]

It’s all gone very quiet here - I hope all is well with you and your Aeromasters.

Meanwhile my build is now underway, starting with the lower wing. I’ll be documenting this with monthly updates on my website but can post a few pictures here too if there’s still interest in this thread.

Looking ahead to the fuselage, I was surprised to see that, on the Super Aeromaster plan at least, there is no former at the leading edge of the wing. Of course, with a relatively small electric motor, the firewall position is also inappropriate so I’ll have to give some thought to former positioning. Of course, knowing where the battery is going to have to go in order to get the cg right would help, but that’s high up on the list of unknowns too!

Cheers,

Trevor

[Nigel R]

Hi Trevor

Taking a bit of a sabbatical from the aeromaster as all my building time is going into this...

[Nigel R]

I'll be back on this thread as soon as the above building site (or at least part of it) is turned into a nice warm insulated workshop! Lots of my gear and airframes are in storage as you might guess.

[Trevor]

Wow, that’s a project on a rather different scale!

Good luck with it. I hope you at least get the roof on in the next week or two.

[Martin McIntosh]

How big is it?

[Martin McIntosh]

Trevor, I used a light ply former faced with thin birch ply at the front of the wing and a ply tongue; no blocks on mine. You should be able to see this on my pics., in fact no blocks used anywhere.

[Nigel R]

Martin, 10x16ft. Plus there is a 9x5 storage shed to move and join on to the side.

 

Should get roof on within next couple of weeks I think. Doing the internal boarding now, roof timber then insulation plus external cladding to follow.

 

I will be very happy to get back to balsa projects after that lot!

Time is of the essence a bit with this one.

Edited By Nigel R on 18/09/2020 23:45:08

[Jonathan M]

That's going to be a very nice shed indeed!

[Martin McIntosh]

Same size as mine. The space soon fills up. I am now using a diesel heater plus a small oil filled electric one on frost setting only.

[Trevor]

Hello All. My first month's progress on the Aeromaster is now up on my website:

**LINK**

As always, it's been a bit slower than I anticipated but so far, no real problems - at least none that I've spotted!

Trevor

[Martin McIntosh]

Glad to see that you have started on this, it should soon become one of your favourite models. I am surprised that the plan of the Super Aeromaster you are using shows dihedral. Mine has none on either wing making construction so much easier. In fact the lack of it allows mine to knife edge as long as I like with very little rudder coupling.

I made all of my ribs from 3/32nd the same by the block method with only the centre ones needing cutting down a bit. I only sheeted the tops of the tips to save weight, also no blocks anywhere on the wing fixings. Even so the weight is 3.5kg with the heavy Laser 80.