John Stainforth

I have one. The first one I bought had a wonky fuselage/fin - the fin was pointing off to the left, so I had that replaced. Generally, the quality of the kit is good, but the front end of the fuselage supporting the engine box is weaker than I would have liked, because so much is cut out for the doors and the front windscreen. I have an OS155 alpha in mine, and with that it flies OK - steady and fairly staid, about as one would expect for a high wing monoplane. The plane has quite a long nose, so with a large i.c. engine it needs some lead in the tail. (With the OS155 the balance is about right.)

Paul, That's an incredible number of models. Possibly a record, I imagine!

OS F works fine in Saito 125. Spend time to really tune the engine well, getting the low end right. You know when you've got it right, because the revs do not change when you remove the glowdriver, and transition smoothly right across the range from slow idle to flat out. Also the fuel consumption is remarkably good when the engine is optimally tuned. Then you don't really have to touch the settings much, ever again.

My Saito 125's go very well with a 16x6 prop (on aerobatic/sport models).

I bought one a few months ago, and I was not impressed. The fuselage was slightly twisted, so the plane flew badly. The shop I bought it from kindly packed up the tailplane to compensate for the twist in the fuselage, after which it flew better. Generally I thought the construction was rather cheap and nasty, more like a toy... except it wasn't cheap, though it looks like about 20 quids worth. This was my fourth foamie, and I remain underwhelmed by them.

It's not all bad news on the local model shop front. My "local" model shop (Redfin in Letchworth) is excellent. It's surprisingly well stocked and the owner (Jason) provides really useful and knowledgeable service.

I prefer the fuselage, simply because there is only one of them. For all the other parts - wings, ailerons, tailplanes, elevators, floats, there are two of them and the construction of the second tends to get a little tedious.

Gator RC (F3a Unlimited) have some excellent carbon fibre wing tubes and sleeves in a range of sizes.

The National Archives at Kew is the place to go. One can search on line, but in the past one could actually visit Kew and search through the old records. The last time I did that was about 15 years ago, so I don't know whether that is still possible. Anyway, when I went I found the records I wanted. All the military records that exist are there. I think it is probably true to say that if they are not there they don't exist or have been lost.

I would use a fret saw close to the bottom of the slot. Then finish with a file - another vote here for the PermaGrit ones.

The Saito 125 is one of the very best Saito engines and when properly tuned is remarkably economic on fuel, to the point that the nitro content required is a trivial issue.

Jon, Thanks for your insight. If this behaviour really is characteristic of the 180 and not the others, why would Saito have singled out this particular engine for such unpleasant treatment? I presumed that their different engines were more or less scale variations of the same basic design.

Charles, Thanks for the interesting idea. I hadn't thought of that. I'll have a look. If the timing was out, I imagine that it would have a pretty drastic effect on performance, but would it cause the symptoms I describe? John Edited By John Stainforth on 03/08/2018 18:54:39

I am a big fan of Saito engines and have two 72's, two 100's, two 125's, a 150 and a 180, and the only one I don't like is the 180. I got mine in the US second-hand but apparently new, so I can't be sure it is an absolutely normal, but it seems very different to the others. I think the compression ratio is a lot higher: it i vicious on starting and absolutely guzzles fuel (totally unlike the others), even after several hours of tuning low end etc. I no longer use it and would be happy to more or less give it away.

Mid to high 20's C is not "very hot", just warm, and nighttime temperatures have been mid to low teens, which is cool; so average 24-hour temperatures have been barely warm. The rest of the world at lower latitudes is generally way warmer. Modellers and model engines cope fine further south in Europe and in the southern US etc. Engines need only mild adjustments to needle valves. Take a look at temperature maps for other parts of the world.

We are lucky enough still to have Laser, OS and Saito 4-stroke glow engines in the 1.20 to 1.60 cu in size range. The Saito 125 is one of the very best 4-strokes of that size. Why these engines are not more popular, I have no idea.

The most remarkable structure for a model wing I have seen recently was on a 40 lb F-16 turbine jet that had crashed. One of the wings was intact (but the owner had thrown this is the trash along with the rest of the wreck), which felt as strong and inflexible as steel. I was intrigued to see how such a strong wing was constructed so I cut it open. I was astonished to find that it had no spars and no ribs except for the root and tip ribs, and was made of 1/16" balsa sheet that had been fibreglassed on both inner and outer surfaces and moulded to the tapered airfoil shape, i.e., a pure monocoque. The only additions were some carbon fibre cloth on the inboard side that had been wrapped into a half tube which was filled with something like Gorilla Glue - I suppose as a spacer.

Clarence Lee Custom Engines in California repairs threads in cylinder heads - if he is still in business.

Most RC clubs in the US are safer in this respect. Pilots are generally meant to be in pilot stations, which are behind the flight line and usually clearly marked with a white line. If a pilot wants to cross the flight line onto the runway, he has to call this out.

I usually find a gobblygook error message after Microsoft have done one of their updates. As far as I am concerned, they might as well have left a message that reads something like this: "Good morning! You will be glad to know that while you were sleeping we have surreptitiously updated your Microsoft operating system. This has created a problem on your computer that you did not have before. But, heh, we're not going to do anything about it, except leave this message that you won't be able to decipher. The good news is that you will probably find that this error is unimportant. We are only leaving it here to irritate you, the customer, because that is our tradition. If you are still not sure who is the boss, you will find that we have changed some of your settings and formats to further irritate you and waste more of your time."

I live in the US part of the time, and the clubs there are generally very accepting of all kinds of power plant. The "electric vs i.c. debate" hardly occurs at all. If I had to guess very rough percentages of engines types at the club to which I belong (a large one in Houston), I would say about 30% electric, 20% 2S glow, 20% 4S glow, 20% 4S petrol, 10 % gas turbine. One category that is almost non-existent is large electric; most of the electric planes are 40 size or less (mainly EDF and trainers). 40-60 size 2S glow is still favoured for trainers. OS 46AX and 55AX are still probably the top selling engines, the cheaper Chinese imitations being found to have considerably shorter life expectancies! Noise is hardly an issue unless the engine in question is actually "unpleasantly" loud. In fact the tradition at my club there is to take the baffles out of OS 2S engines, which increases their power and their noise. Americans generally like plenty of power in their planes, which is possibly why the enthusiasm for electric is not greater. 15-20% nitro in glow fuel is the norm.

I'm sure I've read that a major cause of model engine noise the rotational speed of the prop tips. But, I must say I've always been a bit doubtful of that because of the much lower noise of electric engines running at similar rpm.

Jon, Yes, I have the radial mount for the Laser 200V that you provided about four years ago. I am also a big fan of Saito engines, but their dimensions and mounting spacings are different (often annoyingly by not much) to similar OS and Laser engines. I have several Saitos that are now sitting idle and have fallen into third place for my upcoming projects because of their more limited interchangeability with the others.

Thank goodness so many model suppliers and shops in the UK actually provide very good, prompt service. All my reason experiences with about half a dozen model suppliers have been good.

Jon, The OS radial mount is an extra. The one I am using for an OS155 has serial number 71904200 and is beautifully machined and tapped for M5 bolts - one of the nicest model engine mounts I have seen. Incidentally, The mounting holes in the backplate are for M5 bolts, spaced 54 mm apart at the corners of a square: hence the interchangeability with the Laser 200V. I tried mounting the OS155 with four M4 bolts to four of the eight blind nuts in the firewall that I used to mount the Laser in the same plane. Seemed good and strong, but when I ran the engine the bolts came loose in spite of spring washers. I think this was because the holes drilled in the backplate of the OS mount are M5, so the M4 bolts were a sloppy fit. (It was easy to change out those four M4 blind nuts for M5.) Anyway, this interchangeability of these sizes of OS and Laser engines is intriguing and useful, because it allows the flexibility to experiment with different engines, with different weight and power. I think this should benefit both manufacturers.