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Member postings for TIM Shaw

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

Thread: Rib extrapolation / interpolation
24/05/2017 11:34:58

Profili will only work if you know what the section is - or are otherwise able to create a .dat file for it - but it is a super tool if you do have that information.

Thread: What is it? Glass Fibre fus
23/05/2017 23:59:56

Might be a daft question, but how big is it? - looks much more Flamingo than Phase to me

Thread: FT 3D trimming for knife edge?
22/05/2017 12:55:13

As above, but also be aware it is quite possible to apply too much ruder - try using as little as you can get away with to just hold level flight.

IF you still find it is pulling into a turn then you will need to compensate with elevator, and you might need some opposite aileron as well if its trying to roll with the rudder.

When you have worked out what the model is doing then you might be able to mix this compensation in - I have a scaled down Challenger which needs 10% up elevator slaved to left rudder, and 5% up elevator slaved to right rudder to stop it pulling towards the U/C for instance, but I would strongly advise you figure out what is going on before you reach for the mixes - its very easy to over - complicate things otherwise.

Thread: Pilot Bails Out At Low Level
19/05/2017 15:28:12

Sorry TWR - wrote it this morning, then got distracted by a lunch related issue - indeed, we seem to be of the same mind, and I am a great believer in the law of diminishing returns...

My background is in Chemical Manufacturing, and I remember a particular Technical Director who was one for complicating everything to the nth degree - so much so his underlings used to say he was not a guy to let the facts get in the way of a good theory.

19/05/2017 14:43:23

In an ideal world, the basic Physics is actually very simple.

Ignoring drag, an object accelerates at 9.81 m/s/s, or 32 fps/s

The video timer gives us the 7 second fall time.

An object falling from a height covers distance, S (when I was at school) which is equal to UT + 1/2 x a x t squared.

Since you were flying straight and level, the initial vertical component (or velocity) is zero, hence the first term is also zero, so the distance covered is simply 1/2 x 9.81 x 7 x 7

Which is 240.3m, or 788 feet..

If this were the case, your camera would have hit the ground travelling at a vertical speed given by v = 0 +at, which I think is 69 m/s, or 225fps - about half the muzzle velocity of a non FAC air rifle, and I doubt it would be in the condition it appears to be....

However, in the real world, objects achieve a terminal velocity, at which point the resistance to falling due to aerodynamic effects, primarily drag, equals the accelerative force of gravity, and the object then falls at constant velocity.

So the really interesting question here is just how much drag your camera has.

If you really were 100 feet up, then it only achieved an average speed of about 14 fps, about a tenth of that under ideal conditions.

I guess this really only goes to show how far from ideal our real world actually is....

Thread: SCEN Puma 3
16/05/2017 18:18:13

Hi Nigel

You'll note I specified 45S - this is the one that used a sidewinder mounted, side exhaust 45, with a fully enclosed pipe running underneath, not quite as neat as the original, but, He Ho, not quite as difficult either.

And I'm thinking my nice, new OS 55 AX on a standard muffler will be plenty powerful enough, nice and quiet, and much less bother.

Also frees up the pipe tunnel for retract servos and things.....

But yeah - I downloaded the plan, e-mailed it to a club mate who printed it out, we met at the field, agreed it was very pretty and he admitted he'd done himself a plan too, so I cut him the wing cores and ordered a couple of canopies, and away we went.

Sort of - neither of us are really relishing the challenge and neither of us have got very far.........

16/05/2017 11:38:23

All makes perfect sense to me Nigel, although I'm happy with 1/8" birch FWs right up to piped 61s, usually in conjunction with 1/8" birch tank bay floor and a little light internal glassing.

You're right about formers too - never ceases to amaze me how the older kits used so many, each an opportunity to build another bend into your fuselage....... 3 is plenty.

Same issues on the Aurora drawing actually, can see that undergoing a subtle re-design and possibly some foam decks.

15/05/2017 13:00:13

Hi Nigel

Beginning to sound like a scratch build would have been easier....

Had a quick look at the Outerzone plan and that fuz top looks more like 1/4" sheet to me, you could maybe build it up from strips to gain the needed internal height without impacting too much on the overall shape, and allowing for plenty shape addition / lightening by rounding the corners off.

Personally, I think your firewall would be fine in 1/8" Birch ply, rather than the 1/4" you suggest, and I'd be looking to fit triangle, rather than square longerons.

I think you're right about the doublers though - 1/32" birch every time.

Can't see a way round the nose leg problem. I'm guessing you're going to be running something like a 10x8" APC on that 46SF?

I suspect that if you fly off grass you won't be happy with tiny wheels either. This problem is a little close to home actually - I reckon to have started on an Aurora 45S (well, I've cut the wing and tail cores and mounted the motor mount to the firewall) but I find myself looking at the nose retract mount / tank bay area and not actually doing anything.... I knew there was a reason I preferred taildraggers.

Sunds like fun anyway, and there really isn't much to a fuz after the work you've put into those wings. Will it be ready for the UKCAA event at Huddersfield, June 10th?

Edited By TIM Shaw on 15/05/2017 13:01:36

Thread: Horizon Hobbies
15/05/2017 11:08:11
Posted by Trapper on 15/05/2017 10:13:14:

Thank you for the replies Jonryan and Chris. I have too many DSM/2/X receivers to be able to pay any attention to 'bashers' anyway. Things have improved a lot since my first 'Wee MacGregor' transmitter with the thermionic valve inside it. Heated debate over best brands today is bit like despising a Jaguar sports car, because One prefers to drive an Aston Martin thinking!!

Beautifully put Sir! yes

Thread: Mick Reeves Gangster 63 Lite
13/05/2017 11:21:51

I'm with David.

Many years ago I bought a Curare from a clubmate. He had decided that since everything looks black at a distance, he might as well paint it black......

It VERY rapidly developed big orange and yellow patches on the surfaces though.

Similarly with my Erwins and Pace VXL. Love that naked carbon on the ground, but you really do need some bright colours and contrasting shapes top and bottom when you get into the air.

Black also has a bad habit of showing every surface imperfection up clearly too, although, of course, you won't have any of those......

There's nothing wrong with your TE that a nice long Permagrit can't sort out.....

11/05/2017 18:31:33
Posted by Nigel R on 08/05/2017 16:08:51:

"Ursa Major is very nice Nigel - not unlike the Aurora 45S"

There's a "family resemblance" for sure - If I have it right, the Ursa Major is a smaller version of Cosmos, which was the immediate predecessor to Aurora.

Suffice it to say Nigel I downloaded a few of the Outerzone plans to a memory stick and popped down what used to be our local staples..

I now have full size drawings for the Supra Fly 25, Mystic 30 and the Ursa Major......

I think my excess 35AX is destined for one of the latter 2....

Built to under 4Ibs I am sure they would go well - did I mention I think 4Lbs is about as much as a good 36 / 35 type motor can handle?

As for adhesives, I am a fan of cyano for most woods, aliphatic for wood / foam, epoxy for firewalls, and Gorilla glue for skinning wings.

But yes, I rarely have a full set of finger prints....

Hope your other problems clear up soon and you can get on with the Gangster build, keep us informed

Thread: no fuel
09/05/2017 13:08:55

Hi Nigel

Are you saying that if you open the throttle wide and turn the engine over by hand (glow disconnected) it won't "suck" fuel up, but if you block the exhaust and turn it over you do get fuel into the engine?

Sorry to be pedantic, but "fuel flowing" could mean anything....

If so, then it sounds like you have an air leak around your carburretor somewhere, check it is properly seated and tightened up, and check all the other screws in the area too, its not unknown for them to come loose with vibration.

Is your engine reasonably well set-up at both tick over and full throttle?

Do you filter your fuel? that one will cause arguments I'm sure but I always run a filter in my feed line. If you do, has that worked loose? and if you don't, well, I would fit one.... (ducking down behind the parapet for a few minutes now....)

And when you say all your pipes are checked, you mean properly secured and leak and split free - particularly if you have a rear mounted remote needle..

Assuming all is as it should be, I would remove the main needle and flush through the spraybar with fresh fuel, using your fuel pump, just to make sure there are no foreign objects in there, then refit the needle, maybe 2 turns open? and try it again.

Oh being careful not to cause a hydraulic lock in the process - do the flushing so the fuel drops out of the engine, and turn it over slowly by hand with the silencer facing downwards before thinking about putting a starter on it.



Thread: Martyn's Chippie - G-APYG
09/05/2017 12:48:10

This does look really good Martyn - I have to admit it is not my thing, way too impatient, but I can at least appreciate craftsmanship at work

Thread: elevator unresponsive
09/05/2017 12:42:49

As Martyn said - does it fly ok at normal speed?

Is your horn secure and not floating in the foam?

I don't know the model, but is the servo pulling the elevator up from a top mounted horn, or pushing it up using a horn mounted on the underside. If the latter, a bendy pushrod may be to blame, again allowing blow back at high speed.

Typically, a nose heavy plane will be sluggish on elevator - but failure to pull out of a dive could actually indicate a rearward CG - there is a well-known trimming check for CG, known as the "dive test" Trim for straight and level flight at mid throttle,take it up high, then push the nose down to about 45 degrees and watch what happens.

If the CG is correct, the model should slowly recover to straight and level.

If it's too far forward, it will snap out of the dive rapidly, while if it too far back the nose will tuck under and the dive will steepen. I know this sounds counter - intuitive, but trust me, it's correct, and is to do with where you have your elevator trimmed for straight and level flight.

Thread: Can my glider be towed using it's hi-start hook?
06/05/2017 18:27:15

I don't think its quite that clear cut, TBH.

What control surfaces do you have?

If you have ailerons it is possible to aerotow using a hook, but it is certainly a good idea to ensure both the tug and the glider can release the tow if necessary.

Without ailerons you simply will not be able to aerotow using the hook, unless the idea is to use masses of power and go up vertically, irrespective of what the glider is doing.....

An alternative might be piggy back cradle?

Thread: Mick Reeves Gangster 63 Lite
05/05/2017 14:12:34

Ursa Major is very nice Nigel - not unlike the Aurora 45S I have on the board at the moment, but that looks like a much more complete plan.

Gangster - certainly if Jon is willing to go down the transplant route it would make perfect sense to drill for both mounts now, and probably stand off the 35 from the firewall a little so the spinner backplate on both engines ends up in the same place, and the lighter, 35 will be mounted slightly more forward.

Bit of thought on the throttle linkage to make that adequately adjustable would be a good idea too.

I like to think I do understand 2 stroke engines, never got on with 4 strokes, and all I know about elektrikery is that all things electric work on trapped magic smoke, and if you let it escape, they don't work anymore.....

A member of our club flies the 63 lite on electric very nicely, but I couldn't even begin to equate the power of his set up to an IC one.

Wish this wind would drop a bit - really want to nip up to the field and set up the un-run engine in my new Aerostar 69.....

Thread: SCEN Puma 3
05/05/2017 11:57:11

Looks very nice to me too Nigel.

I've broken threaded rods when I bent them at the end of the threaded bit before now, and I no longer use plastic clevises on any control surfaces after the one I had on the elevator of my second R/C model (KK Student - remember them?) let go at hte bottom of what was supposed to be a square loop.....

Guess that's just me though.

Thread: Mick Reeves Gangster 63 Lite
04/05/2017 23:56:08

All good advice here, I'm sure the 35 would give you a gentle flying Gangster - but I'm not sure that's really what you're after.

And its much more of a pain to fit a bigger mount later, particularly with a built up cowl

So my advice would be go for a 46 or 55 for this plane, OS if you can run to it, but don't rule out a modern SC or ASP either.

Then take a look at Martin Kinders KwickFly 40 drawings, and build either the Mk3 or Mk4 for your 35, changing it a bit if you want, been meaning to do a sort of retrospective build log on my Mk4 because, as a tight wad Yorkshire heretic I've taken a few liberties along the way and still ended up with a sweet flying plane.

I actually have 2 of the 35s, looking at an old USA design called Excalibur 2, and the Prettner Mystic drawings, to find a home for the other.....

If the debate has got you into scratch building and even designing your own, so much the better!

04/05/2017 10:58:15

Thanks for that David!

I do entirely agree about side winder engine mounting though, better for goo avoidance, better for aligning fuel tank and carb center lines, and (almost) impossible to hydraulic lock even with the brutal use of electric starters.

Upright would be a poor second choice, and I hate inverted engines with a passion - bit of a shame really, with a pair of Hanno Specials looking for homes and a Challenger and Touche in the build queue.....

Come to think of it, that might be why they're still in the queue.

04/05/2017 00:11:22

The OS 35 AX is a super little engine - I have one in a Kik Fli 4 / 40, built - loosely- to Martin Kinders drawings.

This is around 53" span and just under 4lbs, and it flies very nicely.

But I consider it is at the lower end of the power requirement for this model, I can fly patterns with it, but Ii do not have unlimited vertical, for example, and while it will probably fly the Gangster 63 lite alright I seriously doubt you will get Pattern style performance from it.

Just to expand on that, in conjunction with the question you ask about throttle.

It is an unfortunate fact that most R/C pilots do not use their throttles as a fully proportional channel, which, of course, it is.

To fly really nice figures you need to be modulating the throttle all the time, and only use full throttle really for take-off and vertical climbs, and getting out of trouble.

If you limit yourself to having to fly with the throttle wide open all the time you will lose out on the flexibility a more appropriately sized engine would give you.

I am sure - provided the carb is properly set up, engines are best run at less than flat out for most of the time. sadly though, many people seem to be happy with max revs all flight.



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