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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: 2 vintage engines, what makes please?
21/03/2020 20:34:43

The bottom one looks very similar to the 1938 Cleveland .488cid 'Tom Thumb' made by Bunch. Scroll down to the eighth picture here: 1930s Model Aircraft Petrol Engines

I'll see what I can find for the other one!

Thread: Insanity seems to be setting in
18/03/2020 12:58:09
Posted by SR 71 on 18/03/2020 12:07:36:

How many undertaker firms are there in the uk at an average of 5K a time its not bad money, do they recycle the coffins, cannot see them burning them as well

They'll be making them with bomb doors soon! :-D

Thread: 1/4 turn wing fixings
12/03/2020 11:51:06

Demon Tweeks who do stuff for motor racing do Camloc parts at reasonable prices. Camlocs

11/03/2020 23:02:23
Posted by Peter Miller on 11/03/2020 20:53:34:

One would also need to arrange a strongish spring at the top somehow

These U clips, with a bit of Dremelling to allow the prongs through, might work as the retainer:

U Clip

Otherwise bolt a U clip each side of the wing bolt hole and modify the bent up edge of the clip to form a ramp either side of a dip for the prongs of the wing bolt to rest in.

11/03/2020 20:26:50

The ST Models MX2 uses a pair of 1/4 turn fasteners to retain the wing. They sell for about £3.50 a pair, so not cheap, but possibly cheaper than buying other types if you have to get more than you need. They are also quite long.
You would need to make up the matching plate though.

ST Model MX2 1/4 turn wing retainers

Thread: Ripmax DARE-U FunFly
06/03/2020 23:03:29

Hi Daniel, If you put the captive nuts in F1 you should be able to try each of the engines, if you get an identical mount for each. Out of your engines, I would probably have gone for either the Irvine 36 or the Super Tigre 34, however either of the FPs should do fine.

I don't recall the weight of mine, I'll weigh it when I can.

Robin

06/03/2020 22:06:22

Daniel, I think you must be telepathic, as I very nearly suggested in my original piece that you use mini servos. My original had them on the ailerons, and I'm quite sure those Tower MG-90S servos would be ok on all the surfaces.
My original had a red and yellow SLEC snake on the elevator, with closed loop control on the rudder. Depending on how you fit the servos, you might be able to sheet in the top of the fuselage under the wing, which would make it a lot stronger.

As both Balsa Cabin and SLEC sell 48" balsa in all the sizes you need for the spars, D-box and trailing edge, why not build the wing in one piece, and do without the dihedral brace/wing joiner? I'm sure the original was two piece only to get the kit in a smaller box. You could thicken the spar web in the middle three bays to say 3/32".

By the way, what engine are you planning to use? My original had an OS25FSR with an 11" x 4" APC prop. The copy had an MDS38 with I think, an APC 12.25" x 3.75" fun fly prop.

One time I got distracted when adjusting the elevator clevis, and when the Dare-U flew, it was pitching up all the time. When I landed, I found this was because the clevis wasn't connected to the elevator horn, just pushing against it!

Cheers, Robin

P.S.  I've just found a picture of the front of ' Shaunie's ' Dare-U in this thread here.  This may help your thrust line query.  Shaunie's Dare-U

 

Edited By Robin Colbourne on 06/03/2020 22:24:33

06/03/2020 15:53:23

I had a Dare U with which I did a lot of flying. It eventually died when I tried to mix flaps and elevator; it all went pear-shaped and dived straight in. I have another one which was built by a friend, who copied mine, and was then given to me when he gave up flying. Unfortunately I'm not living where that one is at the moment, so I won't be able to measure it up for a while.

If you assume the carburettor spray bar outlet wants to be 1/4" to 1/3" below the tank centre line you should be able to extrapolate the engine centre line from there. I know mine hasa round SLEC engine mount and it definitely doesn't stick up above the top of F1.

As a rough guide on wood sizes, I would say:

Fuselage sides & formers: light 1/8" or 3/32" if you want it light.

Spars" 3/8" x 3/16"

Ribs and inner spar webs: 3/32", or 1/16" if you want it light

Leading & trailing edge sheeting and cap strips: 1/16"

All control surfaces: 1/4" square

Fin & Tailplane, Soft 1/4" sheet

F1 Front Former & Undercarrage mount: 2 laminations of 1/8" Ply (you could probably go thinner, say 3/16" total )

If you are making the wing removable, some 1/8" fuselage doublers from the nose tapering away to nothing about 3" behind the wing would help.

As I recall, the undercarriage plate was always ripping out, so a 1/8" tripler extending back about an inch would be worth considering, or better still on both the undercarriage plate and F1, have a full length triangular fillet with the grain following the hypotenuse. It takes a bit of cutting, but is a lot stronger than having the grain along the length of the strip.

Don't forget to put 3mm captive nuts in for the engine mount and undercarriage.  This will save you a lot of heartache later.

Edited By Robin Colbourne on 06/03/2020 16:05:18

Thread: Your experience of Banggood delivery time?
06/03/2020 11:33:19
Posted by SIMON CRAGG on 06/03/2020 06:48:56:

I ordered some of those Lipos last year. To date they still have not arrived. It took me three months to get the money back. Never again!. HK UK and got them in three days.

The impression I get is that the sellers either aren't aware of the Royal Mail's ban on delivering Lipos, or just take a chance on some getting through and refund on the rest. The Royal Mail must have one enormous pile of seized Lipos somewhere!.

06/03/2020 00:40:56

A friend was telling me how several of the people with whom he works get their orders from BangGood and Aliexpress sent to their office, as they aren't home when the postman arrives. Given the long delivery times, most have usually forgotten what they ordered, so its a bit like 'Secret Santa' when they open their parcels!

Thread: Where can i buy 2mm pushrods 750mm long
04/03/2020 10:53:12

Christopher, I haven't tried carbon pushrods myself, I've always used snakes, or, in the old days, 1/4" square balsa pushrods (which I wouldn't recommend).  On throttle linkages, I've used bicycle bowden cable inner with soldered-on snake ends, in tube similar to those in your picture

Given that carbon rods have unidirectional carbon fibres, I would think that using the clamp screw type connector runs the risk of crushing and splitting the carbon fibre rod.

I would be tempted to use snake ends epoxied on with 24hr epoxy, after thoroughly abrading and cleaning (with IPA or meths) the end of the cut to length rod and the inside of the snake end (if you can get a needle file or broken Abrafile into the snake end to abrade it, so much the better). Only do one end at a time, so the position of the first snake end is fixed before attempting the second.
Gently warming the snake end once it is on the carbon rod, will ensure the epoxy thins out and wets into abraded carbon.

If you drill a hole in a piece of wood the size of the threaded end of the snake end, then put it in a vice with the open end pointing up, you can stand the carbon rod in it vertically.  The epoxy will then form a nice fillet and not run down the rod. When you do the inner one on the model, slide the rod in from the tail and have the model pointing nose down to do the same. You can have the snake end attached to a clevis and the servo arm on the servo, so that end is fixed. The weight of the carbon rod should hold it in place, or you can rig up a rubber band at the other end pushing it in.

Edited By Robin Colbourne on 04/03/2020 10:57:08

03/03/2020 20:41:45

SLEC Snakes

or 2mm carbon fibre rod

Thread: Merco Engines
26/02/2020 09:28:09

Here is Mike Billington's Engine Test of the Como 51 in control line stunt form, courtesy of Sceptreflight: Como 51 Engine Test

Thread: I have Got This Far Should I Just Fly it
26/02/2020 09:18:26

With regard to propeller rotation for a twin, both the P-38 Lightning and F-82 Twin Mustang reversed the direction of rotation between the prototype and production aircraft. In the case of the F-82, the airflow over the centre section was so bad that the middle part of the wing between the two fuselages was stalled and the prototype could not leave the ground!

In other words, try both options and see which works best on your model.

Thread: all good things eventually come to an end !
24/02/2020 20:58:15

Stuphedd, I can appresiate the pain you're feeling. At RAE (Royal Aircraft Establishment) Farnborough we had much the same, with the use of taxiways as runways and large grass areas for thermal soarers, There was enough space that the gliding club and aero club could use the appropriate into wind runway without us getting in each other's way. The bi-annual airshow did put a damper on things for a few weeks, but we could live with that. The change from an MOD airfield to a business jet airport was the death knell for the club. Weekend operations were the beginning of the end. Nowadays a row of hangars stands on our usual site.

Looking on the bright side, the fact that the majority of powered models are either electric or four stroke these days, it should be much easier to find a site that can accommodate you. Club fees which cover the cost of field rental, site security and cutting your own grass are all aspects that take some getting used to.

Are the Bedworth and Burbage Aeromodellers a friendly bunch? They look like your nearest established club.

Edited By Robin Colbourne on 24/02/2020 21:25:42

Thread: Is this weather ever going to get better!!!!!!!!!!!!!
24/02/2020 16:57:47

Romeo Whisky, I love the DUKW. If I ever won the lottery, which, given that I don't buy the tickets, is rather unlikely, a DUKW is what I would buy! I blame Airfix for this particular obsession.

Going back to the weather, given that there are only two types; building weather and flying weather, I'm looking forward to this being a truly classic year for new models, particulalry scratchbuilt, from plans and 'proper' kits. Even some of those ones lurking part built in the roof or on top of the wardrobe stand a chance of getting finished and flown.

All that is needed now is some good excuses and artful dodging to avoid the wife/girlfriend with the household 'to do' list.

Thread: Centrifugal clutch pads - from where ?
06/02/2020 19:27:58

You could try Bonz-MX, formerly 'The Ped Shed' They sell spares for Chinese quad bikes, engine driven scooters and mini motos. The most recent phone number I can see for them is 01252 378398 They are in Mytchett, Surrey GU16 6DJ

 

Otherwise, what about theses 52mm clutch shoes?  52mm Clutch Shoes

Edited By Robin Colbourne on 06/02/2020 19:36:52

Thread: Thin Ply
05/02/2020 16:02:43

Nigel, In the design you are building, What is the thin ply used for?

  • Could doublers be replaced with laminations of hard balsa?
  • Could hard points be reinforced with layers of well keyed plastic (e.g. PET or ABS) plastic epoxied on?
  • Could balsa reinforced with cyanoacrylate be used to harden specific areas?

If thin ply is the only thing that will work, and you only need tiny bits, can you get some scraps from a fellow modeller or just buy the ply and keep the rest 'in stock' for your next build?

There is a usually more than one way to skin a cat!

Robin

Thread: Balance point help, advice needed for a Flea!
01/02/2020 01:21:36

According to this Flying Flea Design Notes

Henri Mignet started with the CofG at 41% of the front wing chord, and eventually moved it to 50%, so it may well be that if you are applying conventional aeroplane C of G rules, you've got it too far forward.

Thread: OS FSR engines
01/02/2020 01:11:39

Richard,

'If it ain't broke, don't fix it'!

Have a good look in the exhaust port and if that and everything else looks and feels ok, use it 'as is'. Keep the spare piston & liner for when you really need it.

Selling my 40FSR is my big modelling regret. I'm keeping my eye open for one too.

Robin

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