Bristol Scout - D. Womersley plan 54" span (1:5 1/2 ish)

[GrahamWh]

My son and I started this build from the Traplet plan some months ago and it has been a slow process. He has done a lot of the building but now I am doing most of it to move things along.

Here we are getting started

adding the other side

getting the front bit on

and the back bit

Surprisingly the plan called for 10 swg wire for the tail post - I would have thought it rather heavy, so we have used carbon fibre with brass bushes that line up with corresponding bits of brass tube in the moving tail. However, as we are putting an ASP FS61AR on the front later with a slightly extended cowl to fit it all in, maybe the extra weight would not have been so bad. We shall see.

Electrics in - radio and servos will be powered by a 2S LiFe - no leaky voltage dropping NiMH, I've had enough of them! The dash won't be particularly scale though we will add some instruments...

It may be a while before we have much more progress. We are onto the tail wing and a bit of one main wing is done.

The engine was from HK this time (I have bought from JE too and found their customer service very good). This engine is a delight - really runs well on the bench and swings a 14x4 MA prop at around 10k rpm. It needs to be a 13 or 14 inch prop as the cowl is rather wide. We are aiming to have it flying this year, but may not make the summer unfortunately. I'll update more when we have made some more progress.

[Jon H]

If you want a big prop buy this **LINK**

I know its really big but the blades are very thin and the 61 will turn it. I have no bother turning one on my enya 53 4 stroke at 8500rpm

[GrahamWh]

Thanks Jon - that would look better than a black plastic one.

[Stevo]

Ah! A scale build eh? Subscribed, well done so far!

[GrahamWh]

Thanks Stevo, sorry it will be slow progress though - hope no one gets too bored with it!

[Stevo]

Here's your panel...

[GrahamWh]

I have done a bit of searching for images of the instruments in that panel and I think I will be able to make something up in due course, thanks Stevo.

Got some work done on the tail wing and elevators. Introduced son to applying film which he managed very well.

I've added a bit of carbon fibre to the tail wing for added rigidity and strength - very cheap stuff from HK, even cheaper as my brother gave it to me!

[Stevo]

Film covering?

I lurve the groovy tablecloth!!!

[GrahamWh]

Yes, thanks, the colour matches the linen solartex - one has to plan these things carefully don't you know.

[GrahamWh]

Its been a while since I posted!

I have done some more to the fuse., lower wing started too. Not decided on final colour scheme yet, but I think I will need something like a red chevron/square/stripe on the top wing for orientation purposes - I tend to need something like that so the final scheme may not be an actual one. Just the battery holder to work out now but I may wait until the wings are done so I can see how the CofG is.

Does anyone know of a Bristol Scout that did have a red thing on the top wings - I have searched online but can't see any?

[KiwiKid]

I did a bit of research when building mine, but didn't come across anything like that. I did see some that had roundels with a red external ring and white centre. I find the two tone colour on mine really helps with orientation. You could just add something and crack on that it was to identify the squadron leader, which probably did happen in the field.

[GrahamWh]

Beautiful looking model KiwiKid. Yes I shall probably do something like that - after all some other types had chvrons etc on. Which design have you made - is it the Womersley one?

If so how does it fly? I am doing the version with the larger rudder and ailerons - cheating a bit perhaps! I'm using the aircraft number 1711 as it will be easier to paint - don't know if it actually existed!

[KiwiKid]

I actually picked the framework of mine up in an estate sale. It was only about 2/3 finished with no plans, so there was a bit of head scratching. It's a bit smaller than yours at 44" so probably not the Womersley one. I fly it with a 3S set up, with the 3300 battery inserted into a slanted slot between the undercarriage legs. She fly's well, but will do a snap tip stall if you try and turn with a too slow airspeed. Fortunately I found this out while flying with a bit of height and have to keep it in mind during landing approaches - otherwise a great flying model.

[GrahamWh]

Lovely looking engine in there. Thanks for the warning re tip stall - I'll experiment high up. May alter the ailerons to always be a bit up to reduce the tendency for the tips to stall before the rest of the wing if mine has it.

[GrahamWh]

3 1/2 years on from the start of the build, and after a lot of breaks, it is finally ready for a maiden flight. There are still minor things I can do, but it is ready.

Setting up a jig to get wing incidence and all strut lengths right

Hatch for refueling

I was a bit shocked when I weighed it - with the 1 Lb balancing weight in the nose it weighs 9Lb 5oz. The Flair puppeteer I built with the same box structure wings is larger and a lot lighter. Apart from using solartex rather than solarfilm I am struggling to work out why.

Hopefully the ASP 61 four stroke will be enough with a 13x6 prop. WeboCalc says the stall speed will be around 22 mph - does this all sound okay for a 54" span biplane?

When suitable weather comes and I get the maiden done I will update with its performance.

Cheers,

Graham

[GrahamWh]

This has been maidened now. The flight 2 weeks ago only lasted 3 minutes or so until the engine cut due to a push rod screw wearing loose and stopping the exhaust valve opening enough. Then it rained and that was that for the day. It seemed pretty nose heavy though needing a lot of down elevator in the dive test.

I took it to the field again today with a 1/2 oz nut cable-tied to the tail (equivalent to removing 2 oz from the nose) and flew it again. Still nose heavy so tied on another nut, then a third for the next flight and it seems better now - gently pulling out of the dive with thumb off the elevator after being correctly trimmed for level flight. I've also reduced the aileron rates as it was pretty twitchy in the roll.

I'll get rid of the 3 nuts at the back and go from 16 oz nose weight to 10 oz.

I was using an MA K series 14x6 prop today. I'm sticking to plastic MA ones for now as I don't want to risk damaging a nice wooden one like the one Jon kindly recommended earlier until the balance is right and I am sure it won't nose over on the ground. The engine seemed to be struggling with it a bit though and I was flying on 2/3 to 3/4 throttle most of the time.

It does look a bit odd with just one roundel on the top wing so I might end up putting another on.

Edited By GrahamWh on 24/11/2018 16:37:22