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Author Topic: Thomas Designs Bristol Scout  (Read 7297 times)
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Pete Fardell
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« Reply #50 on: February 28, 2016, 05:16:33 PM »

What an utterly gorgeous model. This, and also Ralph's, are inspirational and make me want to build a Scout of my own, even if those levels of workmanship and finesse are way beyond me. Can't wait for the flying news!

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Ian Melville
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« Reply #51 on: February 29, 2016, 06:42:22 AM »

Great work Mike.

Now blogged on the real Granddads' Bristol Scout build.

https://bristolscout.wordpress.com/2016/02/29/223-112-scale-model/
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Marco
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« Reply #52 on: February 29, 2016, 02:53:54 PM »

Mike, it's a great build. Take a picture in black and white with the proper background and no one will notice it is a model. congratulations
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Jack Plane
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« Reply #53 on: March 01, 2016, 12:55:20 PM »

What an utterly gorgeous model. This, and also Ralph's, are inspirational and make me want to build a Scout of my own, even if those levels of workmanship and finesse are way beyond me. Can't wait for the flying news!

Don't worry Pete, I'll eventually post pictures of the outcome (whenever that'll be!) of my own appallingly-hashed peanut Scout build... which should make us mere mortals feel much, much better!   Grin

My only observation on these two Scouts par excellence are the absence of caster oil stains and other operational wear and tear...

... err, I'll get me coat!
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ZK-AUD
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« Reply #54 on: March 01, 2016, 01:48:59 PM »

Just a quick note to say thank you for the all of your kind and generous comments.  I would like to say although I'm probably what's called an experienced builder (I should be after nearly 50 years!) I'm nothing out of the ordinary and the real credit here has to go firstly to 1/12 scale which is a good size to work with and secondly to the superb engineering of the Thomas Designs kit, which meant I could concentrate on detailing and not worry too much about structures.  Concentrating on detailing and coming up with cunning plans to make things appear real but at the same time add as little weight as possible is the real joy of this end of the hobby for me.

Seeing Ralph's peanut Scout (replete now with Ranken Dart holes!) flying in the video he posted has made me very excited indeed about the prospect of getting my one in the air.

As far as progress goes I'm working on the nose end now.  I have to develop a cunning plan for a hidden version of my patent never-fail freewheel clutch and also a version of my patent multi adjustable thrustline device to fit this nose plug.  Also I have decided that I don't like the embossed bolt representations on the front plate of the Le Rhone crankcase so I'm making another one (just the front plate!)  I have found that Plastruct do a rather splendid line in styrene hex rod in tiny sizes starting at 0.5mm A/F (also 0.8mm 1.0mm 1.2mm and upwards).  This should arrive by the end of the week and slices of hex rod will furnish much better representations of the bolt heads

Also had some joy this week playing around with Evergreen styrene tube.  I had a pack of 3/32 OD styrene tube and hit on the idea of heating and drawing it.  This worked and I was able to draw it our to hypodermic needle size and still be tube.  This is an alternative to my paper tube wrapped around a mandrel and hardened with cyano trick for making working turnbuckles.  A bit heavier but certainly easier.
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ZK-AUD
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« Reply #55 on: March 02, 2016, 02:53:58 AM »

Took the Scout outside in the calm this evening for some test glides (still not finished but you know how it is!) As indicated in my initial lob onto the duvet it glides straight, long, stable and slow.  Glides of around 20 feet from shoulder height landing nicely on the wheels.  Happy with that.
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DavidJP
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« Reply #56 on: March 02, 2016, 09:30:07 AM »

You are such a show off!! Wink Smiley
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skyraider
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« Reply #57 on: March 02, 2016, 03:15:04 PM »

Nice work Mike!. That Bristol is some work of art. And that engine
is something else. Could there be possibly be some kits or short kits
for the engine down the road in 1:12? Just wondering. I'm pretty sure
there would be a market for it. William Brothers used to do them years
ago. Now most of their stuff in 1/6 scale and up.

Skyraider
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ZK-AUD
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« Reply #58 on: March 02, 2016, 03:37:02 PM »

Thanks Skyraider,

I know that anyone who has built one of Greg Thomas' kits would agree that they are works of art.  The kit came with all 9 Williams Bros cylinders and I think they are still available - If so I will probably buy a gross of them as I have a number of 1/12 WW1 projects in mind.  Making the crankcase as I did was an easy job really, - the 3D file can be scaled up or down as required and vac forming is fun. You may be aware that I have been working with Avetek here in NZ to assist with the development of new rubber powered scale kits.  The first was the Tiger Moth which appears over in Buy Sell trade under the Reverse S hook thread.  Some of the other projects (including the upcoming one) require a rotary engine and thoughts are certainly turning to how we could produce a high quality representation for the average builder.
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ZK-AUD
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« Reply #59 on: March 02, 2016, 03:39:48 PM »

You are such a show off!! Wink Smiley

I resemble that comment!
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RalphS
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« Reply #60 on: March 03, 2016, 05:12:56 AM »


 I have been working with Avetek here in NZ to assist with the development of new rubber powered scale kits. 

A Bristol Scout at 24" thereabouts would be nice. 

Nice to know that the thread subject is looking promising in early flight testing.  My little object seems to have remarkable stability and has always landed on it's wheels.

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DavidJP
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« Reply #61 on: March 03, 2016, 05:45:16 AM »

The idea of the engines is wonderful Mike and will answer the dreams of very many people.  I do hope it works.  

By the way having got the Tiger Moth kit I can say it is a gem and the instructions are a work of art.  I am intending to hone my skills a bit more before I start it and also get a couple of other things out of the way first.  The building is no problem as the thought that has been applied means it is fairly straight forward.  It is the finishing that will be the challenge.  And that you can't "kit"

Any chance of a SpadXIII in a kit please?

Finally having a couple of Wingnut plastic kits clearly there is something in the air down there to produce such high standards in the kit world.
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ZK-AUD
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« Reply #62 on: March 05, 2016, 03:43:47 AM »

Time for an update.

I decided I couldn't live with the crankcase front plate.  I had just embossed the plastic from the other side to represent the front cover bolt heads but it was not convincing.  I have re-engineered it and built the nose plug in behind.  The crankshaft extension is hardwood dowel turned to the correct taper and glued firmly in place.  You can just see that I have applied a tiny meniscus of epoxy around the base of the crankshaft extension which when it is hard will represent the turned  radius on the real item.  The bolt heads are slices of 1mm A/F hex section styrene.  On the real one I think these are actually domed nuts so I may put a dab of glue on top of each one which will form a rounded top.  Feel free to tell me if I'm becoming a rivet-counter!  The rear of the nose plug and into the hardwood crankshaft extension is bored out in a cone shape so that the prop shaft bearing can be fine-adjusted for thrustlines with the aid of my patent device.  A bit of cleaning up and a splash of paint and we are nearly there.

I took her over to Gywn Avenell's place the other night (he of Avetek fame) and we did some test glides down a nice slope he has on his property.  This particular slope seems to approximate the glide ratio of the Scout with the result that you get some really nice long glides that give you plenty of time to see and assess everything. Doesn't seem to be anything to do except wind up the rubber band!
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ZK-AUD
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« Reply #63 on: March 05, 2016, 09:04:03 PM »

Just got back in from an absolutely magical morning's flying.  Our rubber scale enthusiasts all came out to take advantage of several hours of dead calm and ever increasing lift.  The Avetek Tiger Moth did 1m 24 on 1800 turns.  Very happy indeed.

Here is progress on the nose plug.  You will see how I made my thrustline adjuster - essentially 2 circuit board forks that trap the brass tube shaft bearing and lock it in the desired position with little cap screws.  the outer fork (Mr Downthrust) is tapped into the lower fork (Mr Sidethrust) which in turn is screwed into a piece of ply let into the nose block, which is tapped and then hardened with Cyano.  Each fork has an elongated slot to allow for travel.

The brass tube will have a flange at both ends to keep it in position

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DavidJP
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« Reply #64 on: March 06, 2016, 05:10:25 AM »

Bloody hell!, that is impressive!  You are very imaginative as well.  I feel positively brain dead in comparison.
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Tommy Wee
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« Reply #65 on: March 06, 2016, 12:22:14 PM »

Same feeling here, David Wink

Gorgeous engine and those thrust adjustment pieces are a good solution. No balsa/ply wedges here...

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« Reply #66 on: March 15, 2016, 10:52:50 PM »

I have been re-working the prop following the method given to me by Greg Thomas, which is rather cunning and makes a nicer looking item out of a plastic job.

Essentially the prop is trimmed away at the hub to allow the installation of thin brass discs front and rear. 

I drilled out the plastic hub to take a brass tube bush but before installing the bush I put an over size length of tube through the hub and then slid drilled square balsa blocks over the tube front and rear to ensure the discs were perfectly square and aligned before gluing them with thick cyano. 

Once dry I removed the blocks and oversize tube and soldered in the actual bush.

Final stage is to poo all in between and around the two discs with builders bog and then carve and sand to a nice shape.

By the time I did my usual thinning trick on the blades the overall weight was only about 2g heavier than the original prop weight and as that is in the middle rather than out on the blades that's just fine.

After I took this photo I painted the prop and had hoped to post a picture of the final article but the well thinned acrylic bloomed on me badly -  Rats!  So I'll sand it back and do it again - no biggie but annoying when you are this close.
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« Reply #67 on: March 18, 2016, 04:23:15 AM »

Hi everyone, a little progress to report.  The engine is now installed and I have repainted the prop after it was made to blush for shame!  Note the gunge now liberally beslobbered over the engine.  I had fun with this  AK brand engine oil wash which I slopped all over the pristine engine.  More to be slopped in a realistic manner on the aluminium section underneath the front fuselage / wing roots etc

A good chance of being finished this weekend
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« Reply #68 on: March 18, 2016, 05:34:49 PM »

And here again this time with the prop driver plate - this is just styrene sheet with the styrene hex heads glued on and a bit of paint
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ZK-AUD
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« Reply #69 on: March 19, 2016, 08:47:31 PM »

Nose plug is finally complete.  My club mates all know that good nose hardware is my particular hobby horse as I've bored them all senseless on the subject but it really is the heart and soul of a successful rubber model and you so frequently see good models with built-in disadvantages in the front end.  The prop ended up looking so nice that I didn't want any manky bits hanging off the front so I developed a version of the standard dog clutch system so that it sits in neatly behind the prop hub.

The first disc you see is soldered to the front of the brass tube shaft bearing and provides a good seat for the jasco ball race.

The disc after the ball race is soldered to the prop shaft.  This takes all of the tension load and bears on the front surface of the ball race.  Soldered to this disc is the little nub that acts as the prop driver.  This takes the place of what would usually be the wire loop in the standard set-up.

The small washer soldered to the shaft just forward of this is the rear prop limiter.  The prop 'floats' between this and the front retainer, so the prop never has any tension on it.

The drive dog is in a tube with a carefully soldered retainer that is then buried in the rear of the prop hub and does not extend right through and spoil the look of the front face.

The only un-scale-like item on view is therefore the retainer disc on the very front but neatly soldered it's not too obtrusive.

Good solder joints are necessary.  I get the work plenty hot and let the solder flow and get a good meniscus for strength.  Clean metal to metal joints and a bit of Duzall flux help.

I also re-made the main body of my thrustline adjuster in dural as the circuit board wasn't that great for threading the adjuster screws.

Very happy with this result
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skyraider
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« Reply #70 on: March 19, 2016, 09:09:29 PM »

Nice work Mike, and Very impressive.  Looking forward to
hearing of the flights.

Skyraider
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Graham Banham
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« Reply #71 on: March 20, 2016, 04:30:13 AM »

I'm running out of superlatives for this build Mike!

Superb work. I would say museum quality, but it's better than that.

Graham
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« Reply #72 on: March 20, 2016, 04:39:58 AM »

I was just looking back a few posts and realised that I must have had some brain fade and mis-credited the cunning method of pimping the plastic prop.  The credit for this actually goes to Rich Weber who as I have previously mentioned was not only the inspiration for this build but who has unstintingly provided me with advice and cool techniques to try.   

Virtually finished now - just  the control cables to go but I will tackle those after initial flight trimmimg and I will treat myself to one of Mr Banks' 1/12 pilots.  Weight is 85g which is a little lighter than I expected and slightly nose heavy - happy problem!!  I put a small motor in it tonight and gave it a wind-up.  All systems working perfectly.
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RalphS
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« Reply #73 on: March 20, 2016, 06:19:16 AM »

Nearly there.  Looking good.  Glad you didn't put the hucks starter lookalike on the front.

Ralph
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« Reply #74 on: March 20, 2016, 05:43:47 PM »

Me again,

in case anyone was wondering where I managed to find the perfect sized washers that were a good fit on my prop shaft but were the correct outside diameter, here is my sordid little secret:  I make my own using this really simple jig which should be self explanatory, and my Ryobi table sander (most useful tool I own).  Drill the block and your metal sheet for the internal diameter you need, poke a bit of your wire in the hole as a spigot, cut the blank to a roughly octagonal shape and then put the block up against the sanding disc and rotate the work.  You can drill the block with the radius oversize and 'fine tune' the block on the sander - simple, effective, guaranteed results
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