John Bisset

Looking at my plans for the Precedent Stampe, measuring the tailplane incidence (lower surface of tailplane) with reference to the upper fuselage longerons, which make a ~ good level reference, the tailplane measures at 4 degrees nose up. (That sounds a lot. Mine is a kit from ~30 years ago, still not built. I will have to hunt around for an instrcution booklet; it's not in the box, so I must have taken it out to dream over.) It's not so easy from the plans to determine wing incidence accurately. Looking at the plan and making my best guess of chord line, then transposing that up using (nautical !) parallel rules,the lower wing incidence appears to be around 5.5 degrees nose up. I'd suggest both my figures are +/- around 0.5 degree. Does that help? I think both wings should have the same incidence at the root. I have an aircraft engineer friend who is rebuilding a full size Stampe right now, and is close to re-assembling wings and tailplane. I could ask him what the values should be, though the model values may differ. I think his son has a Precedent Stampe part built.

That's beautiful work, cymaz, and a lovely aeroplane. I'd be scared to fly it ! Edited By John Bisset on 09/08/2019 15:41:04

Part of the challenge with these apparently 'flimsy' fixings is our human tendency to equate 'bigger' with 'stronger'. Actually of course, that often isn't so. Toughness - which is typically more important for durability - may be better with a slimmer, lighter piece of structure. The stiffness of a hollow tube compared to an equivalent weight solid rod is a classic example. That said, when I first looked at a Hornet Moth's folding mechanism I too was taken aback at its simplicity and lightness. And yes the bolts typically used to secure engines in light aircraft do look undersized, especially if you plan to do aerobatics. Thinking about the torque loads alone makes you wince. I used to fly Pawnee glider tugs. Hefty, tough design made for rugged use. Now I fly a Eurofox, an uprated microlight aircraft which has some radio control model size fixings and some R/C adapted minor control attachments. It is in fact a very capable and strong aircraft, though I still have a hankering for the reassuring bulk of the (expensive to run) Pawnee! And if you ever see a modern airliner with the wing root fairings removed, the actual retaining bolts are quite surprisingly slender and few in number. That big root section looks impressively solid... An excellent materials engineer and trainer whom I knew said that the most astonishing about metals is not how strong they are but how weak. They all have much higher Young's moduli than their in service strengths might suggest. Why? - because they are full of imperfections. Still, best not tell the 'general public' that !

A most useful set of posts Colin - and a salutary lesson for us all. Thank you for this cautionary tale and I hope you continue to recover fast. My wife, also a pilot, normally helps me with hand launching when necessary. We both read your account with great care & some trepidation - and see common elements in what we do. We shall be changing our launch style immediately! As you say, we should really think of these as cutting tools - mobile buzz saws. Shudder! I shall try to think of these from now on in the same way as the prop on a fullsize aeroplane, which gets a wide berth. Perhaps the old days of hand swinging small model engines had acclimatised me to thinking sloppily about them.

I will be interested to know how well the wing slots work out - certainly did a fine job for low speed control on the Turbulent. I wonder, is part of the problem here that the wing loading has presumably gone up? A smaller model than the original Wot 4 will have less wing area and while total weight will be down, it may well not be in proportion. This is a common re-sizing problem. Smaller motor, battery and ESC will be lighter but maybe not so much. That would explain the 'drops out of the sky when throttle cut' performance. It might also help explain some of the squirrely behaviour, since a higher wing loading will put more emphasis on the wingtip vortices and any slight build variations at the tips could show up, be magnifiied. If some of the pilots are also pilots of larger Wot 4s, are people subconsciously expecting the benign handling of that machine too? (I recall a fullsize two seat sailplane we put a wingtip camera on years ago, overseas. This was long before GoPros etc. The camera was small but the rudder required to hold straight in flight surprised us. So did the stall - quite a vicious wing drop we'd never experienced before. Taping a similar sized block of wood to the other tip evened things out, but after that and a couple of other surprises we stopped doing ad-hoc mods. We realised why test pilots are required- even small changes can make a big difference! )

That is useful information about Halfords Martin, thanks. My previous source for cellulose paint was a local motor parts supplier, but they now only seem to have acrylics and two pack. I too have some basic colours in cellulose stored away, plus some old cellulose paint mixers which I got from a garage which was giving up spraying. Those I have to keep thinning back, since the tins and jars leak slowly. Luckily cellulose paint can recover quite well.

I agree that you need to be careful with acetone fumes Martin. Should have said that. I use it for cleaning up after glassfibre work, amongst other things. Plenty ventilation helps - ideally an open air job! (I am old enough to remember the nausea involved with using trichloroethylene in confined spaces long ago. It was even used as a clothes cleaner at one time, before we realised how nasty it was!) Of course acetone will remove cellulose paint, but it is a darn good degreaser! I agree that acrylics can be a pain. Much more hot & miss for me than good old fashioned cellulose.

As far as paint is concerned over Solartex, I've sprayed both cellulose and acrylic paints successfully. Acrylics do need a bit more care in surface cleanliness before application. Adhesion on clean Solartex was good. I did use some Iso propyl alcohol once on what looked to be a rather grubby surface. That need some time to dry and a gentle rub with a soft (lint free) cloth helped things along. ( I wondered about using acetone but suspected that it would attack the Solartex. Never tried it!) AS Bert said, Balsaloc helps if you have adhesion problems, though not something I've seen with Solartex. I have had that trouble with Solarfilm, which seems more sensitive to iron temperature variation. It also didn't take paint well for me - maybe too smooth so the paint doesn't key well I suppose.

Are traffic wardens and police speed traps run by private companies? When did that happen? That sounds quite appalling. I rather doubt there would be enough business for a private company to take this on,except in the very busiest of areas.

Posted by Don Fry on 07/08/2019 11:05:21: Not a barrister, but normal use is wot normal people use it for. That's a ball flying through the air. Our use would be an unusual use, however much it is normal to us. And if the normal was as, say, a private airfield? Not common here, but in France many small airfields have power, gliding, parachuting and model flying all co-existing.

Posted by Jason-I on 06/08/2019 18:50:25: So, if our normal use and enjoyment of the land is flying model aircraft to 400ft, then surely we can claim this as our airspace. That is a most interesting thought, Jason. I fly almost exclusively on private land, by arrangement with the owners. It is very specifically not open to the general public for other reasons, so that argument may be useful. John B

Thank you , all of you - most useful. This is one of the several things I like about this site - there are so many knowledgeable people prepared to share their information! I had wondered if the 'silicone wire' was what was needed. I shall buy some and try it out. (Annoyed I hadn't thought to check the Max site, Martin. George is very helpful & an interesting chap to talk with - I could have asked when speaking to him the other day!) Cheers, John B

A query on wiring. I have been extending some leads in a couple of my models, to re-position a UBEC. I am also tempted to lengthen the leads from an ESC. However, I don’t have any wire which is as flexible as the wiring typically used on ESCs, or UBECs. Diameter, or more accurately cross sectional is the critical point for power capability but forp flexibility multi stranding? I presume I need multi core copper wire with very fine individual strands. Is that correct? Can anyone advise me what type of wire to ask for and if possible, where I might be able to buy it. I do realise I may need to add a capacitor if I increase the ESC to battery lengths. Adding say 10cm maximum to the ESC to motor run I think I can get away with. Thanks. John

Ah - a very good point Simon., Our 'Lords & Masters' would be delighted to find another way to tax us and restrict our freedoms! That said, all the light aircraft airfields and glider sites are already listed and shown on CAA charts, so there can't be any significant additional costs to justify in simply requiring any drone restriction systems to include these areas. That would be a safety benefit. You'd think anyone wishing to run a commercial drone delivery service would want to know about our sites as well, so their expensive beasties could avoid them. Hmm - too simple !

It does seem reasonable to me that if the CAA and DfT are going to insist on this registration and 'competency' testing folly, we should in turn insist that they recognise where we fly in order that restrictions may be applied to protect our operations. Aside from the media hype & hysteria about the danger of drones vs fullsize aircarft - still a debatable area - the other purpose in all this is to make it easier for the supposed future drone delivery services etc to be licensed and authorised. This is seen by some as a potential money maker for government, wrongly in my view. Hence they want us corralled and in a position where we can easily taken account of, or deterred completely. If we are registered at cost to ourselves we should therefore ensure that our sites are noted and hence can be avoided by delivery drones,w which will be GPS controlled. This is something which light aircraft and gliding sites will need to ensure as well. Few are airfields with control zones. I strongly suspect that the DfT will only view licensed airfield official ATZs as relevant. May need to get these things registered ASAP!

Oh, thank you both. That is most kind. I will have to do a good job building now!

Thanks Steve. Unfortunately my nearest hobby shop is ~120 miles away. Only A WH Smiths here,a ndthey have long since returned any spare stock.

Hi. Does anyone know where I might be able to buy a copy of the June issue of RCME to get the 'L'il Cub' plan? I missed it, by being away on holiday - bother. It looks as though the print version is not available as a back issue here - I presume it has run out. The idea of building a machine with both slats and flaps for seriously slow flying is great fun. I'd really like to work out a way to duplicate the automatic slats which the Rallye aircraft, though in small scale friction may be too high for air loads to overcome. First though, to build a simpler fixed slat aircraft ! Regards, John Bisset Edited By John Bisset on 02/08/2019 12:49:22

Thanks both - not a TLA I'd come across before! And boy, my profession is full of those darn acronyms !

Shaun, Pat - A silly question ; what does the acronym WOT mean here? I am being immensely thick today!

Thanks Shaun, that make sense. I have been wondering about a wattmeter for a while.

Thank you. Sound as though the existing prop may have been undersized for this combination. Why does prop size go up ads the supplied battery voltage goes down? Or am I mis-reading your comments saying a 7S battery would use a 13x6 and a 3S battery would use a 15x8 prop?

Hello all. I have a question relating about a model I bought second hand some time ago. I bought it cheap with little information, mostly for the servos and ESC etc. However I’d like to try flying it before I do any ‘reduce to produce’. The motor is noted as being ‘500kvA’. The only other notation is ’42 x 600’ written by a previous owner on the engine bulkhead. The ESC is rated at 80 amp, made by RC Smart, an RS-SET-80. The prop which cam fitted is a 12 x 06. Total flying weight of the machine, which is a 6ft span pseudo Cub look alike – construction similar to the machine by Black Horse from what I have seen online – will be around 5 ½ to 6lbs. I am intending to use either a 4 cell Lipo or a 5 cell Lipo to power this. I don’t need high power to weight ratios; my model flying is fairly sedate, more scale style than wild aerobatics, so a minimum of 70 watts per pound is sufficient. It seems as though a 4 cell Lipo will suffice, but I’m not sure about prop sizing. Suck it and see is one option of course! Any comments or suggestions?

A fascinating series of posts - and thank you for the pictures of the Wot 4 Pro, Jakob. I have just completed a rebuild of an old Wot 4 Mk2 for electric power, with a lighter fuselage. Intrigued to see the lighter tail section of the Pro, similar to what I built. I had wondered about making a built up wing for myself - I have never seen any foam wing Wot 4s, up until now. Looks good, might 'reverse engineer' one using an old foam wing as a rib template. Have never seen the extended rudder you mention; also interesting. I agree closed loop can be awkward to set up in that narrow fuselage - it is my preference, which I was cursing last night when trying to reattach a sprung connector. I am now wondering about my oldest Wot 4, from ~thirty years ago. Is it even a Mk2? I have been tempted a few times to build a Twin Wot - two fuselages with a common centre section, on the style of the Twin Mustang. I thought that might be what a Wot 4 squared might be! Or maybe that's a Wot 8 ... John B

Posted by David P Williams on 20/07/2019 14:24:25: I was up at 3am watching it live (I was 18) and I seem to remember that the picture of the ladder waiting for Neil Armstrong to descend was initially upside down, and I couldn't work out what I was looking at. Is that my memory, or was it our flaky telly, or was that how it happened? Clever of the conspirators to build that element in just to make it seem more realistic ! Yes, that is right, the picture was at first upside down as transmitted, for some reason , possibly to do with the re-transmission from the Australian NASA pick up, if my memory is correct. Mission Control swapped it around after a few minutes. I had the same problem as you - couldn't work out what I was seeing. Truly magnificent achievement. Interesting that several of the astronauts later admitted how low they had rated their chances of survival, let alone success. Impressive in so many ways.