Bristol M1 conversion to leccy?

[Bob Cotsford]

OK, as it says on the tin what options would forumites suggest for a Balsa USA Bristol M1. This is a 60" first war monoplane that the box quotes as 6-6 3/4lb flying weight, for 40-60 2str or 60-90 4str (load gulp at the upper limit suggestion!). Personally I think it's more like 40-45 2str or 60-70 4 str but what do I know? Anyway, I was looking at the stretched nose, 7" cowl and 5 3/4" wide fuselage and wondering what electric setup could provide extra ballast to allow for a shorter scale nose. A 15" prop would look about right.

What do I have to hand - 6S 3700, 4S 3850 and 3S 2200 packs but only the 3S will fit across the fuselage without mods. A battery mount through both inner sides with a suitable hatch in the outer side might be an option for larger packs. Maybe a ring of 8 (4S2P) A123s round the inside of the cowl? Danny?

Motors to suit? Please don't include 'OS' or 'MVVS' in the brand name, I ain't made of money! HK is my friend

 

Edited By Bob Cotsford on 04/07/2016 11:31:42

[PatMc]

I've been watching this guy's progress he intends going with an Emax GT2826 710kv & 4s 4000 lipos. He was at the stage of decor last time I looked but he hasn't posted anymore since 28th April.

The BUSA M1 is around the same size & weight as my Magnatilla. Power on that is a Turnigy 3548 900kv, 4s 4000 or 4s 2650 & 12x6 APC clone. AUW is 98oz , battery lives where the fuel tank used to, with access through the firewall via the cut out of the horseshoe shape cowl.

Edited By PatMc on 04/07/2016 12:51:34

[Jon H]

Laser 70, 15x5 Turnigy type A wooden prop @ 9000rpm

That will well overpower it though. A friend has a magnatilla flying on a saito 50 and we have propped that way up to keep the performance in check

[IanN]

Posted by Bob Cotsford on 04/07/2016 11:30:13:

OK, as it says on the tin what options would forumites suggest for a Balsa USA Bristol M1. This is a 60" first war monoplane that the box quotes as 6-6 3/4lb flying weight, for 40-60 2str or 60-90 4str (load gulp at the upper limit suggestion!).

There were quite a few "lardy" builds of this one on the RC groups forum a while back. One of our transatlantic friends even put a 26cc petrol in his

[Bob Cotsford]

Dear Gods, I take it the negative G maneuvers left a bit to be desired!

I do have an ASP FS61, but that leaves it with the over-length nose and without the characteristic spinner - the spinners available are a bit flimsy for IC. Just fancied something I could throw in the car with just a couple of batteries and a transmitter. I was actually looking at 50xx motors just because it needs the weight up front and these are in the same ballpark as a 61 4 stroke. With these I reckon I could shorten the nose by about 1 1/4" at least if I can get the battery weight forward too,.

[Bob Cotsford]

Pat, I'd seen that but 710kV motor turning a 14" prop still sounds like it would need a lot of ballast. I was wondering about something nearer 4-500kv for 4S or even lower for 6S, wafting a nice big prop round.

Maybe on 6S 'wafting' might not be the best term to use?

[PatMc]

Bob, he seems to have put a lot of thought into lightening the tail feathers, which might would help towards achieving the shorter nose. A heavier motor run with a prop/battery combo that's only a moderate load to it would help with the cg & reduce stress on the motor at the same time. If the target weight is 6lb, you're only going to need about 450W [My Maggie flies nicely on 460W at WOT]. With a suitable 15" prop, I'd estimate a motor weighing 200 - 250g, around 600 - 700kv on 4s & 400 - 500kv on 6s.

Edited By PatMc on 04/07/2016 15:48:02

[Ton van Munsteren]

Hi Bob,

Great model the Busa Bristol M1C, iam flying it for many years already.

First with Nicad and a brushed motor and now with a geared brushless motor, batt is a Lipo 4S 4000ma and its just a great model to fly.

Not 100% sure but I think the prop is a 16x8 with more than enough power to do WW1 aerobatics.

Did a lot of modification to the model to get the weight down and made the wing in two panels.

Here are some pics the rest is in my album **LINK**

Ton

[Bob Cotsford]

Thanks for the link Ton, you have gone to town on your M1! The clearviews and radiused root LE add a lot to the character. Did you shorten the nose on yours? I doubt I'll spend too much time changing the kit as it's intended as a knock-about model - or at least that's the intent at this point in time. Who knows what will happen once the kit hits the building board.

ps - is that the Kavan spinner or the Traplet's one?

Edited By Bob Cotsford on 04/07/2016 18:00:48

[Bob Cotsford]

Posted by PatMc on 04/07/2016 15:42:19:

Bob, he seems to have put a lot of thought into lightening the tail feathers, which might would help towards achieving the shorter nose. A heavier motor run with a prop/battery combo that's only a moderate load to it would help with the cg & reduce stress on the motor at the same time. If the target weight is 6lb, you're only going to need about 450W [My Maggie flies nicely on 460W at WOT]. With a suitable 15" prop, I'd estimate a motor weighing 200 - 250g, around 600 - 700kv on 4s & 400 - 500kv on 6s.

Edited By PatMc on 04/07/2016 15:48:02

Yes, my 1 1/2 strutter is quite lively on around 80W/lb, and I think my Baronette is in the same ballpark. The built-up tail looks to be a good start as per Ton's example. The RCG build compared weights and saved a couple of ounces by replacing the sheet tail surfaces - that's significant with such a short nose.

[Ton van Munsteren]

Bob,

Its my homemade spinner made from fiberglass over a balsa and foam mold.

No the nose is not shorten, for better scale it should be much shorter but then you will need a big motor to have the CG in the right place..

Ton