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Member postings for Bob Cotsford

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

Thread: Good news thread.
13/06/2019 12:13:55

Plumber has just left, the expected £110 bill ended up as £75. He arrived on time, had everything he needed to complete the job, wiped his boots on the way in, didn't smoke and has all the approvals for plumbing and central heating work. I'd rate that as the equivalent of a small lottery winlaugh

Thread: Galaxy models mystic - help on electric conversion
13/06/2019 11:13:52

second attempt topost - grr!

A logfile from my Provost (5055 430kv, 6S, either 15*8 or 15*10, can't remember which offhand) peaks at 56A with a fresh battery, then later peaks are around 46-48A but the average current is probably around 30A, it's surprising how little time is spent on a steady throttle!

provost log.jpg

Thread: Model Noise Level - Interesting Findings
11/06/2019 10:59:40

My guess is that part of the perceived difference between IC and electric is the way the sound level is recorded. IIRC it is a smoothed figure, so while the electric's noise is constant and what you hear is what you get recorded the IC produces pulses of sound which are averaged out to give a resulting sound level. What you hear are the peaks so it sounds louder.

I'd try a different prop driver and spinner, I had something similar with the supplied unit on a HH Carbon Z Cub. The buzz it made sounded like a 4 stroke at full throttle, a replacement spinner and a standard prop driver cured it.

Thread: Anyone for a Tiffie?
11/06/2019 10:41:19

11g, as you say, that's worth 2oz of lead in the nose. I'm surprised by the previous structure, I wonder why three layers of sheet? I have the plans squirreled away somewhere from when they were published, but I don't think I kept the build articles.

11/06/2019 10:41:16

11g, as you say, that's worth 2oz of lead in the nose. I'm surprised by the previous structure, I wonder why three layers of sheet? I have the plans squirreled away somewhere from when they were published, but I don't think I kept the build articles.

Thread: Galaxy models mystic - help on electric conversion
08/06/2019 15:59:16

Propdrives seem ok, at least the 42mm ones that I have do. 580kv turning a 15*8? That 2000W is the 15 second rating, e-calc thinks a 15*8 will draw 107A for 2165W and that it will cook itself. I have a couple of 595kv motors running on 6S but I'm really limited to 12 or 13" props on those giving me around 1200-1300W. Ok in a WotsWot and Bolero but I would really look for something around 430-500kv for the Mystic.

As Denis points out, you only need 1200w or so, with the 120 Surpass (1500W-ish?) mine had power enough to fly big, open classic-style ballistic aerobatics.  The 1800W topping my suggested range would be hooligan territory.

Edited By Bob Cotsford on 08/06/2019 16:01:29

07/06/2019 20:45:59

Hi Paul, you should see some of the messages that I end up sending via sms! I'm no electric expert, but what I've suggested has worked for me on half a dozen models.

07/06/2019 16:58:20

ps - my Mystic came well used, and judging by the bulkhead drillings it had been flown at some point with a good sized petrol motor. It was nylon covered with a good coat of colour on top so no doubt it could have been built a lot lighter. I still doubt whether a .60 two stroke would have made for a very exciting model, with a 1.20 four stroke it was a nice club aerobat.

07/06/2019 16:51:53

I had an OS 120 Surpass in my Mystic (it was a bit of a porker!) so off the top of my head I'd say you want around a 1300-1800 watt motor depending on how you like to fly. So, first question - what cell count are you looking at running? For 6s you are looking at a 75- 85A rating, for 8s 50-60A. Something like an Aerodrive 5055 430kv on 6S for 1300W or 5065 320kv on 8S for more poke might be suitable, though everyone has their favourites often dependant on budget. I have several .60-.90 two stroke sized models running 5055 430kv motors on 6S with 15*8-15*10 props, it seems a fairly safe setup so far pulling up to 1300W. 6S esc's are relatively cheap, 8S ones tend to cost a fair bit more so watch out for that unless you have a fat wallet.

Thread: Interesting reply from email to Richard Moriarty, CAA
06/06/2019 18:01:11
Posted by john stones 1 on 06/06/2019 17:40:59:
Posted by Gary Manuel on 06/06/2019 13:03:41:
Posted by Jason-I on 06/06/2019 12:13:46:
Posted by john stones 1 on 06/06/2019 11:17:06:

If we withhold payement, we can't fly, if we can't fly, we get no members, what happens to our club ? who pays for the grass cuts, and maintenance. Show me "The plan".

Register as a pilot (free): Check

Take the stupid test (free) to 'prove' you are safe: Check

Put your contact details on all your models so plod can track you down: Check

Insurance through BMFA: Check

Fly at a permitted location: Check

Then go fly. You are registered and you can be tracked down by the details on your model. That's compliant enough with the law for me. Anything else is just an unfair tax that should not be entertained.

Edited By Jason-I on 06/06/2019 12:14:02

Sounds like a plan to me.

Is there a risk of me getting my collar felt, for not stumping up the money ?

Flying a UAV not carrying the marking of a valid, registered operator?

06/06/2019 13:13:11

and if the insurance has a clause added that the model must be carrying a valid registration? It's probably already covered somewhere in a clause stating that the model must be flown in a legal manner.

Edited By Bob Cotsford on 06/06/2019 13:14:19

05/06/2019 19:58:28

Well, I've written (and complained following their reponses) to the DFT, the CAA and my MP Jess Phillips so that should sort things out sad, and now I've added my name to the petition.

Thread: Electric Motor 'clunk' When Opening Throttle
05/06/2019 14:55:54

Have you checked the grubscrews that hold the can onto the motor shaft? I doubt it would make much noise if there were play but it's the only other possibility that I can see for a noise maker.

Thread: Fuel Soaked ply
05/06/2019 14:49:29

One of the early claims for CA glues in modelling was that it would stick oily parts together so was ideal for field repairs. I think CA on ply does benefit from abrading the surface, I don't know whether it's really removing 'release agents' from the ply or just opening up the pressed surface grain allowing the glue to penetrate.

You are a braver man than I am Phil, I have a WW fuselage in similar condition to yours but my upper wing pylon was destroyed along with the front two formers. I put Paypal on the case and replaced the plane. Maybe one day I'll see what can be done with the remains but not yet a while!

Edited By Bob Cotsford on 05/06/2019 14:50:19

Thread: Interesting reply from email to Richard Moriarty, CAA
05/06/2019 09:03:42

One does wonder whether this is equitable with the stance regarding cyclists. They are not required to pay for cyclepaths and cycle parking areas nor are they required to take tests or register despite the number of accidents involving cyclists and the proven use of cycles to carry out crimes.

No doubt there are plenty of other activities that could equally be used as a comparison.

Just saying...

Edited By Bob Cotsford on 05/06/2019 09:04:57

Thread: Now that Solartex has gone...
03/06/2019 10:49:50

If you don't want to mess with compressors and sprayguns then either brush on a thin coat of household vynil emulsion or Humbrol matt enamel (goes further than you'd think) topped with clear polyurethane or use Halfords or similar spray acrylics topped with 2k clear spray from a can off one of the many internet sellers. Use a mask when spraying!

My 1 1/2 Strutter built in 1980 was still fuel proof using clear poly over Humbrol enamel when I repainted it with some old Polymax paints (remember them?) a couple of years ago. 30 odd years had left it a bit faded and ratty,

Thread: Interesting reply from email to Richard Moriarty, CAA
02/06/2019 16:41:43

oh well, I guess that this thread is well and truly off the rails so if you can't beat 'em:

There is no doubting the historic cyclical variations in the climate, just as there is no doubting the fact that man's technological development over the last 150 years is a significant factor that is accelerating the change.

I like fences, especially if I can keep a foot in each camp face 1

02/06/2019 14:34:38

Are conspiracy theory posts really appropriate on this thread? Commercial drone pressure theories excepted of course...

Thread: Mount for an older small brushless bell motor
01/06/2019 16:31:48

Just as well, mine is 10mm OD!

01/06/2019 10:30:17

What is the diameter of the spigot? I have some old 24xx series motor parts including the mount. If it will fit, it's yours.

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