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Member postings for John Stainforth

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

Thread: Modes 1 or 2
14/02/2020 23:45:16

I am in the US at the moment, and rest assured Mode 2 absolutely dominates - virtually no one flies Mode 1. I think this is because there is more cross-over with full-size aviation: there are for more modelers who also fly full-size planes in the US compared with the UK.

Thread: Seagull Hurricane Laser
12/02/2020 17:34:12

The fullsize Hurricane did not have a standard 12%-ish thick wing section at the root, but a whopping 18%. This was one of the main reasons it was 40 mph slower than the Spitfire. This is how the wing sections compare:

Hurricane ClarkYH cambered 18% root 12% tip

Bf 109 NACA 23 cambered 14.8% root  10.5% tip

Spitfire NACA 22 cambered 13%  root  6% tip

The drag coefficents of the Hurricane's wing section were much higher than the Spitfire at low Reynolds Numbers, so a thick wing model Hurricane would be particularly bad in this respect.

Overall the Spitfire's wing had a quite extraordinary performance, a late model in 1944 achieving the highest speed of any piston engined aircraft, I think. I also remember reading somewhere that Sir Sidney Camm regarded putting such a thick wing on the Hurricane a his "biggest mistake".

Edited By John Stainforth on 12/02/2020 17:36:08

Thread: Covering a sheeted surface in tissue and dope.
03/01/2020 04:08:49

Seeing JD8's photo of a Mercury Matador reminds me of sketch that my brother found that I did in 1965 (in blue and red biro) of our single channel RC Matador. We called it "Matador 2" because we essentially rebuilt the whole plane, beefing it right up by adding LE sheeting and covering it with nylon fabric. By it's designation "S12", it was already our 12th model aircraft. (We starting making model aircraft and other things around 1959!)matadorjsketch-0381.jpg

Edited By John Stainforth on 03/01/2020 04:13:27

Edited By John Stainforth on 03/01/2020 04:15:49

Thread: The Gov't, CAA, BMFA & UAV legislation thread
02/01/2020 23:56:46

There's some bad news from America today. The FAA are proposing some much tougher rules on model and drone flying there. Why is this relevant to us? Because we end up following very similar rules, with a time lag.

Thread: Dust extractor
24/12/2019 14:33:27

I bought a Jet air filtration system about 8 years ago. Worked well up until a few months ago, when the motor packed in; nice and quiet with three speeds. The filtration unit uses a standard-looking A/C filter. I sanded parts directly in front of the filter. All the fine dust goes straight into the filter (which can be cleaned out by banging against an outside wall). The heavier stuff falls onto the floor beneath where it is easily swept up.

The only snag was the cost, which IIRC was about 160 pounds, which stuck me as rather a lot for what is basically an electric motor in a tin box. I see that the current equivalent model is now over 300 pounds.

Thread: A new caption competition - winner declared!
02/12/2019 02:44:22

"I am the Ghost of Brexit Future"

27/11/2019 13:21:49

I am Vlad the Impaler. I grabbed your plane out of the air, I can grab barbed wire fences with impunity, and now I am about to grab your face!

Thread: Laser Engines - Technical questions
21/11/2019 18:35:55
Posted by Jon - Laser Engines on 21/11/2019 13:07:34:
Posted by John Stainforth on 21/11/2019 12:49:26:

Jon,

I think there would be a significant demand for an inline 50cc glow engine amongst the scale fraternity.

Incidentally, what are the problems of using methylated spirits as a base? (Would the piridine coke the engine up?) Dirt cheap and readily available.

Meths is not likely to be very pure. My guess is it wouldnt be a very consistent fuel and im not sure how a gluwplug would take it. Its also more expensive than methanol from what i can see.

As a side note, its the oil and nitro which cranks up the price of glow fuel. Go skinny on both and you bring the cost down.

And i admit, this is only my opinion, but if you take a warbird like the ones being referenced here is fuel cost really an issue? Minimum 350 for the wood, perhaps the same again for retracts and oleos, another 200 at least for radio gear. An engine could be 300-700 depending on what you get, so call it 500 as a middle ground. Now we are up near £1500 and we could easily spend another 500 on bits, paint, a pilot, spinner, scale details..whatever. So, if we call it an 1800 - 2 grand model, does it really matter than you used 20 quids worth of glow fuel to fly it for a weekend? To me 20 quid for a fun weekend out in the sun (yea right) is cheap.

Jon, I totally agree with you re the cost of glow fuel. I think it's a vastly exaggerated issue. Most model flyers I know (including myself) spend far more on ethanol-containing beverages than on glow fuel - without batting an eyelid!

21/11/2019 12:49:26

Jon,

I think there would be a significant demand for an inline 50cc glow engine amongst the scale fraternity.

Incidentally, what are the problems of using methylated spirits as a base? (Would the piridine coke the engine up?) Dirt cheap and readily available.

15/11/2019 16:21:24
Posted by bert baker on 15/11/2019 15:24:00:
Posted by John Stainforth on 15/11/2019 06:54:49:

Don,

Is it really such a good idea to hang a weight on a crankshaft? I would be interested in Jon's opinion.

The boat brigade, car and helicopter fans have done it for many years,

Good point.

15/11/2019 06:54:49

Don,

Is it really such a good idea to hang a weight on a crankshaft? I would be interested in Jon's opinion.

Thread: How much does an RC hot air balloon weigh?
05/11/2019 19:05:01

Shaun,

No conundrum. Your model plane in the air weighs essentially the same (mass times gravitational acceleration) as on the ground.

Thread: Design assistance request!
03/11/2019 11:45:43

Rhino has a beautiful command called Sweep in which on "sweeps" a cross-section along one or two "rails". The command Sweep2 uses two rails. For wings that have the same (scaled) airfoil section throughout, one selects the airfoil section with a mouse click, and the planform lines of the LE and TE of the wing (to use as rails) and preferably the point at the very wing tip, and bingo, the whole surface of the wing is produced instantaneously.

All the 3D drafting programs have a myriad of ways to loft surfaces, and the trick is to find what works best in a given situation.

Thread: Laser cutting
10/10/2019 12:46:25

Belair Kits do a very good job.

Thread: A sticky glassing problem!
07/10/2019 20:25:38

For glassing my Supermarine S6b modeI, I used L285 epoxy resin and hardener, available from Fighteraces, with absolutely no stickiness problems. The resin and hardener are mixed  carefully in the ratio 2.5:1 by weight.

The only stickiness I find occasionally is in the thin remnants of resin on the walls of the mixing pot. It seems that when mixing there is a stagnant fluid boundary layer next to the pot wall that does not get properly stirred with the rest of the mixture. This is not a problem, because I always decant the mixed resin into a broad plastic dish to avoid a thermal runaway in the mixing pot, which has too small a fluid surface area to volume ratio to allow the heat of reaction to get out of the mixture fast enough. This decanting has the extra benefit of leaving the poorly mixed resin on the pot surface behind in the pot.

Edited By John Stainforth on 07/10/2019 20:35:35

Edited By John Stainforth on 07/10/2019 20:37:21

Thread: A Terrifying story
01/10/2019 18:57:06

I have just had to apply for an over 70's driving license. This can be done completely online; no forms have to be posted in, and new photographs. As far as eyesight is concerned, one just has to tick a box stating that one's eyesight is OK for driving. In the USA, every time one has to get a driving license renewed (which is every five or ten years), one has to go in person to a local driving test center where one is photographed and given an eye test on the spot. That seems far more sensible to me than our system.

Thread: Collapse of Thomas Cook
24/09/2019 00:57:22
Posted by 2W on 23/09/2019 21:01:21:

It seems to me that if, by the law, all bonuses should limited and be paid only for improvements in company performance and to all employees. In the event of a company failure, all company directors and board members should then be required to repay all their bonuses (and as I am sure, others would also say all income above the minimum wage) paid in the last 7 years. This would certainly focus the directors' minds on the profitability and the of the future of the business.

William

In the company I worked for, our basic salary was called our Base Pay and our annual bonus (if any) Performance Related Pay. For an employee to get a bonus, both the company and the employee had to perform at an above average level. The company measured its performance with a combination of the economic metrics (profitability, share performance, etc) relative to four other similar companies in the same business sector. This was a "zero-sum game" in that the average performance of the five companies would get a Company Performance Factor of 1.0, with the better performing companies scoring, say, 1.2 and 1.4 and the poorer performers scoring, say, 0.9, 0.8 and 0.7. Every single employee was also given an Individual Performance Ranking and, again, in each team the average score had to be 1.0. The Company and Individual scores were then multiplied together. If the company score was 1.1, say and the individual score was 1.1, say, the overall performance factor for the individual would be 1.21 who would then get a 21% bonus. Conversely, if the company performance was ranked as 0.8 and the individual's performance was 1.2, say, the overall performance factor would be 0.96 - less than 1.0 - so the employee would get no bonus in spite of his/her better than average performance. In the case of Thomas Cook, the company performance factor for the last year would have been something like 0.2, which would make it virtually impossible for any individual in the company, including the managing director, to get any bonus. The system was not perfect, but pretty fair overall, I thought.

Thread: Glenns models cap 232
24/09/2019 00:24:04
Posted by bert baker on 23/09/2019 20:09:57:

The T nut is as per the instruction manual that comes with the kit

the flat head of the nut is against the Fuz side not the spikes,

It's the spikes that rip your fingers when fitting them

I get that. The problem is that the spikes are pointed straight outwards in the direction of any centrifugal force.

But I stand corrected. Frictional forces along the sides of the wing tubes are apparently sufficient to hold wings on, so I have been wasting my time with wing bolts.

23/09/2019 18:25:56

Bert,

I was not querying the single bolt so much as the T nut mounted the wrong way round. Whose recommendation?

Any outward force (which is what the wing bolt is intended to counter) will be pulling straight out on the spikes of the T-bolt. Also, the flange of the T-bolt will not allow a flush fit of the wing to the fuselage. Tightening the wing bolt could then crush the material of the outer surface of the fuselage (if balsa), which would tend to produce a "countersink" in the fuselage. The act of tightening the wing bolt will then be tending to extract the T-bolt from the wing.

I would have thought that a high rate of roll could produce a not insignificant centrifugal force on the wings.

23/09/2019 03:27:32

Wow! Are you saying that each wing of an aerobatic model weighing over 22 lbs is held on with a single bolt into a captive nut the wrong way round? I think you have been a bit lucky and are pushing your luck. I'm not sure this would pass a safety inspection in most clubs.

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