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: A new caption competition - winner declared!|
"I am the Ghost of Brexit Future"
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|
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!
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.
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?|
No conundrum. Your model plane in the air weighs essentially the same (mass times gravitational acceleration) as on the ground.
|Thread: Design assistance request!|
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|
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!
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