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: Laser cutting|
Belair Kits do a very good job.
|Thread: A sticky glassing problem!|
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|
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|
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|
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.
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.
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.
|Thread: Latest CAA Update|
I worry for future generations.
|Thread: Hangar 9 Ultra Stik 10cc|
Yes, it's a very versatile airframe that has not changed much over the years, and I am sure it would be equally good with glow, electric or petrol ("gas" power plants.
The Ultra Stik was not designed around a gas engine: it came out way before gas engines became the new fad. In the US, Ultra Stiks and Great Planes Stiks (there's not much to choose between the two) are equivalent to the UK WOT 4's, and are at least as good. The classic weak spot of the Stiks is the rear fuselage because it tapers to a very narrow cross-section just in front of the tailplane, at a point where there are slots for the elevator and rudder push-rods. If the balsa in the rear fuselage is soft, there is a real chance that you could lose your plane to flutter. In the US most people beef up the rear fuselage of their Stiks with extra plywood plates etc, particularly when they put more powerful engines up front (usually, still glow, not gasoline).
|Thread: Forum members' new models: Let's see them.|
That's a beautiful soaring site you have there. Where is it?
|Thread: Prop failure|
Wow! Loyal customer gets slapped down!
|Thread: Silicon fuel tube rotting?|
I leave some of my models for three month periods in cupboards with essentially no daylight. Yet I often have problems with tanks and rotted fuel tubing. I suspect the main culprit is the nitromethane in any residual fuel in the tanks and tubing. Nitromethane is a very aggressive chemical and the resistance of neoprene and silicon rubbers to it is poor. I looked this up on the web a short while ago and was interested to see that nitromethane is also cited as an excellent solvent of cyanoacrylate adhesives! (And it is also reckoned now to be more explosive than TNT!)
I should add that I like fairly high nitro fuels (typically 12 to 15%) for most of my engines.
Edited By John Stainforth on 07/08/2019 12:39:00
|Thread: Prop failure|
One sure-fire way to prevent propellor failure on four-stroke V engines would be for the manufacturer to take those engines out of production.
|Thread: Steel ruler|
To check whether a straight edge is straight, just look down it. The eye is as good as a laser beam for judging that.
|Thread: RCM&E September Issue.|
Let's hope the latest issue just fell through the editorial cracks with the change of editorship. It gives the impression of not really having been edited at all!
|Thread: Problem with air in fuel line. Pulse xt40|
I have found that when I leave models for several months without flying, that were 100% fine before the hiatus, failures of the radio and tank system are very common when I return to the models. Neoprene and copper tubing, tends to deteriorate and crack, as do rubber bungs, and tanks do crack. I have quite a large pile of useless old tanks in the US and UK that have failed in these various ways. One thing I have learnt is to fill up fuel tanks very gently on the first fill of the day, since vigorous filling builds up pressure in the tank that can force out deteriorated bungs. Also: always fill up the first tank (at least) of the day with the canopy off so that one can spot a leak at the earliest opportunity - rather than suddenly seeing fuel poring out through the bottom of the fuselage!
|Thread: OS threads|
So, Foxfan, you're a bit of a naturist, are you!?
|Thread: The demise of. ASP/SC|
Why are so many people on this website cheering on the demise of i.c. model engines? I've always regarded them as one of the cornerstones of our hobby. (I.C. engines got me into the hobby almost 60 years ago.)
The prejudice against i.c. is not quite as great in the US as the UK. But world-wide, the hobby is in big trouble. The ARFs are rapidly disappearing, the manufacturers and importers are closing shop, and soon there will be nothing to hang i.c. motors on.
|Thread: ASP etc gone|
Peter, many of the OS engines are available, e.g., 46AX $147 (US) and 132 pounds (UK); OS55AX $170 (US) and 147 pounds (UK). Are these outrageous prices? I think not. For comparison the PAW 49 is currently selling in the UK at 195 pounds, so I am not sure why PAW should be rubbing their hands in glee.
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