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Member postings for Robin Colbourne

Here is a list of all the postings Robin Colbourne has made in our forums. Click on a thread name to jump to the thread.

Thread: BMFA numbers. Is this true, or a gross exaggeration?
13/11/2019 23:02:09

The driving force for BMFA affiliated clubs was to a large extent driven by the loss of sites due to noisy engines. Now that small electric models are in most cases unobtrusive, why would you drive miles to hand launch over a crowded mown strip or piece of tarmac if you don't need it.? In some respects model flying has returned to where it was in the 1930s, 40s & 50s, with the flying of small models in the nearest local park.

Will the BMFA wait until country members are more than 50% of their membership, or else they have all left and bought the FPVUK insurance, before they ask if they are serving them as well as club members? For example, if one country member teaches another, are they insured? BMFA regulations tended to be written around flying on affliated club sites. That was fine when the norm was a .40 powered trainer, but those days have gone.

13/11/2019 00:02:09
Posted by Ray Wood 4 on 12/11/2019 22:32:51:

Hi All,

I come from the generation who could watch 30 different RAF types of aeroplanes at Biggin Hill in 1970 ! How many do we have today 4 ?? It was inspirational to us model builders

Regards Ray

Excluding UAVs, gliders, wobblycopters, anything rented and the BBMF, I make it thirteen distinct types right now:

Hawk, Lightning II, Typhoon, C-130J, A400M, C-17, Airseeker, Sentinel, AWACS, King Air, Islander/Defender, Poseidon, BAe 146.

During the war, albeit a period of six years, the RAF operated around 100 different types. It must have been a logistics nightmare!

Ray, my list for 1970 shows 31 types; which one didn't make it to Biggin Hill? wink

Edited By Robin Colbourne on 13/11/2019 00:03:06

Thread: Engine projects
12/11/2019 20:09:19

Jack, on the single cylinder engine, the bottom of the piston acts as the valve controlling flow from the carburettor into the crankcase. On the twin, I suspect a reed valve between the carburettor and crankcase does the job, in the same way as on a Cox Babe Bee 049.

When the pistons are moving apart (going up the cylinders), there will be a negative pressure in the crankcase, which opens the reed valves allowing the air fuel mix in. When the pistons move towards each other (descending in the cylinders) the reed valve shuts, squeezing the fuel/air mixture up the transfer ports on each cylinder and into the combustion chambers.

Thread: BMFA numbers. Is this true, or a gross exaggeration?
12/11/2019 18:48:30

Whilst youngsters are the most obvious source of new blood, they are by no means the only one. Large numbers of people buy models and don't complete them or do complete them, but don't fly them, either through lack of time, lack of knowledge,or fear of breaking it on the first flight. These models then gather dust on top of a wardrobe, or in the attic whilst the pressures of family life take precedence*.

Once the children have lives and transport of their own, spare time re-emerges and there's your target audience.

Try advertising** an event to encouraging people to bring their part-built and unflown models along, receive some constructive advice on completing them, and give them a taster on the club trainer with a buddy box. If you have a suitable venue, arrange for a member or members to give a regular evening class to the newcomers so when spring flying weather arrives, they have the knowledge and a correctly built and set up model to make a 'flying start'.

*This statement is based on two years of running an adult education class for would-be R/C modellers. The vast majority of the 45 who attended were aged 40 to 80, and had already started a kit years before.

**Don't pay money for this; local newspapers and radio stations will do editorials and local news items for free.

Thread: Engine projects
11/11/2019 20:36:13

Jack, It sounds a bit like the Quadra twin our department at RAE Farnborough had made for a UAV in the 1980s. It used two Quadra 50 cylinders.

Thread: I know what it is but do you ?
08/11/2019 10:49:03

A bigger tailwheel may well help too, both to reduce the rolling resistance and the angle of incidence in the initial acceleration.

Full-size Grob 109s have a very large tailwheel about 8.5" diameter.

Thread: Fuel Agitation
08/11/2019 10:37:54

Nexus do a felt clunk: Felt Clunk

Thread: I know what it is but do you ?
07/11/2019 17:25:26

As this isn't going to be a particularly fast model, and its the acceleration across the ground that's the issue, how about trying one of those 12.25" x 3.75" APC funfly props?

Thread: Looking for a 1930s low wing racer plan
05/11/2019 14:34:49

Napier-Heston Racer?

Napier Heston Racer

There's a control line version on Outerzone which would give the shape: Napier Heston Racer

More here: Napier Heston Racer History

Thread: Where are the 50cc engines?
04/11/2019 18:09:25
Posted by Martyn K on 04/11/2019 16:52:53:

I thought OS had stopped producing all 2 stroke glow motors along with SC/ASP.

I am not sure what the status is on OF FS engines, I believe that the smaller motors have been dropped as well.

Basically, everyone (nearly) is going electric..

Very sad indeed if that is the case.

Ripmax and Just Engines both list OS two stroke engines. Whether that is current production or just old stock, I have no idea. Every Enya I clicked on on Steve Webb Models was shown as 'out of stock'.

04/11/2019 16:34:32
Posted by Peter Christy on 03/11/2019 09:34:01:
Posted by Jason-I on 02/11/2019 17:09:58:

OS still sell a 0.15, a 0.35 and a 0.46.....

Perhaps I should have said affordable sub-.40 size engines! Over £100 for a .15? Really? And has anyone (other than Just Engines) actually got any in stock?

Even in Japan, that 15 is over £70! So I say again, where are the small affordable engines?



Pete, Its simple economics. Thanks to cheap, powerful and quiet electric motors, the demand for glow engines is a tiny percentage of what it was. Development, tooling and production costs have to be recouped over a much smaller number of engines than in the past, so the unit price to the consumer goes up, further reducing the demand. There are plenty of new and nearly new engines on ebay etc. for less than the manufacturers can make them for, so only the niche engines will find a market.
That Mills .75 in Tom Sharp's posting cost a weeks wages when it was new. Even OS prices of £100 for a .15LA is actually a bargain, its just that we've been spoilt in recent years!

Thread: source of 2mm Depron?
29/10/2019 12:11:04
Posted by Richard Harris on 28/10/2019 09:39:13:

Last time I bought some was from SAMS but they have run out.

If you can cope with 3mm B&Q sell it HERE , they also sell 6 and 10mm thicknesses


Richard, Do you happen to know how may sheets are in the 3mm B&Q pack? Their advert doesn't say, and the maths suggests its 13.3 sheets! dont know

Thread: R/C Hand Launched Glider Identification?
29/10/2019 11:19:55

That's right Tom, they were great shows!

R/C powered include the Clancy Aviation Lazy Bee, David Boddington designed the Beam Bender biplane (vaguely an indoor Panic for DC Dart power) and the Roof Raiser moonplane (Cox TD 020) specially for the event. There was also Keilkraft Phantom control line team racing and an aerobatic helicopter which erupted into a mushroom cloud of bits after a back flip into the floor. All these were engine powered, no electric stuff then that I recall. There was also a rubber powered condenser tissue covered 'penny plane' which was doing really well until its circles down the hall crossed paths with one of the Phantom team racers. That was never going to end well, although it must be said the Phantom didn't miss a beat...


28/10/2019 23:43:07

Years ago at the Model Engineer Exhibition, they flew R/C hand launched gliders inside. When I saw one of these gliders at a club bring and buy, I snapped it up. I would now like to refurbish it and get it back in the air, so have been looking for info on it, but I can't remember its name. I have a feeling it was either a Radio Modeller plan or possibly an Avicraft kit. Maybe you can help?

If you've had one and flown it, what battery & servos did you use and what was it like to fly?

Wingspan is 39 1/4" or 1 metre.


Edited By Robin Colbourne on 28/10/2019 23:43:40

Thread: source of 2mm Depron?
27/10/2019 23:25:50

I bought some at Old Warden at the Ebenezer day in May, but the seller (Sams Models?) did say it was the last he had. This chap on ebay has some: 2mm Depron on Ebay


Edited By Robin Colbourne on 27/10/2019 23:30:46

Thread: silver solarfilm
22/10/2019 12:34:27


Are you absolutely sure the bad stuff was definitely Solarfilm? There was a company called K&C who used to sell their ends of rolls of a similar product at Sandown and other shows, and amongst that stuff certainly had rolls which wouldn't stick, or peeled off very easily (writing from bitter experience...).

Talking to Derek Hardman AKA 'Mr Solarfilm' at a show many years later, he said he was often received the blame for the results of this other cheaper product, as it was by then no longer on the market, so people assumed if they had some that it was genuine Solarfilm.


Thread: Black 5 twin IC from Sarik Hobbies - Anyone Know it?
14/10/2019 23:32:25

It looks a bit like a twin-engined version of Dan Santich's Hots or Super Hots.

Thread: New build rubber powered balsa
14/10/2019 23:21:33

Hi David,

If you want a reliable free flight rubber powered model, you want one which will survive the trimming flights unscathed. A big help in that direction is to have the wings and tail held on by rubber bands, so they spring off in a hard 'arrival', thus saving the structure.

Thunder Tiger are making kits of several of the Keil Kraft designs which have this feature, including the 30" Ajax, 32" Ace, 32" Senator and 40" Gipsy. Many others are available as plans on Outerzone; the 24" Eaglet and 32" Competitor are two good strong designs which fly well.

Edited By Robin Colbourne on 14/10/2019 23:23:15

Thread: Engine projects
13/10/2019 13:09:39
Posted by Robin Colbourne on 13/10/2019 01:26:29:

Hi Jeff, Is your latest project based upon a Super Tigre 71?

A rare beast if it is!

For some reason I couldn't edit, this, so to be specific, I meant the Super Tigre G71 RV, although it could equally well be the G60 RV.

13/10/2019 01:26:29

Hi Jeff, Is your latest project based upon a Super Tigre 71?

A rare beast if it is!

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