Mark Powell 2

I'm surprised. I have found Sig kits to be good. And a message about wind turbines or whatever on the plan is hardly an excuse for tapered spars and rubbish die cutting, is it?

Perhaps JE might have tried testing one before selling them. Or, to be fair, you just got a 'bad' one. There have, as far as I know, been  no other adverse comments. But JE's action  now, to China, indicates otherwise. Personalli I will stick to makes I know. and have direct experience of, having been caught out before Edited By Mark Powell 2 on 03/09/2012 10:57:54 Edited By Mark Powell 2 on 03/09/2012 11:00:32

No. I just thought they might be as they have certain similarities to the MVVS ones andf the Evolution ones made for them by MVVS.. I see the bigger ones, such as your 17cc, have a different carburettor to the 9cc one that Peter complained of. Until I saw Peter's comments it would have been the one I would have gone for as I really only want a little one. No longer.

Ultimate, Zenoah (a division of Komatsu) Chainsaw engines the lot of them. Others - you can tell them at a glance by their very short front bearing, thus they have a 'stuck on' long prop driver to compensate. Lots of them, but getting less. Tempted, I agree with everyone's cleanliness and low running cost comments. I have not tried one yet but probably will. Fancy the 50cc DA or the 33 or 50cc OS, but expensive and a bit big for what I want. I will probablt 'test the water' soon. An engine is an engine. Yes. I lokked under the bonnet of a TVR once. Would get no pleasure in owning such a lash up.   Edited By Mark Powell 2 on 03/09/2012 09:54:15

The Just Engines NGH one looks nice. From its appearance I would suggest it is made by MVVS in the Czech Repubic. They are good at engines.. They also make the Evolution ones. Petrol engines are feeble compared to glow engines. They use less fuel because the fuel/air mix for correct operation is less than half that of a glow engine. 0.8 bhp for 9cc. Less power than even a four stroke glow. My OS 46 AX two stroke develops twice the power for less weight.and 1.5cc less., not that the capacity matters. Would I buy one? Perhaps, but never one of these horrible , crude, heavy, modified chainsaw engines like so many of the others. Peter, just saw your post. They sell it, advertise it as good, then you discover after trying to use it you have to buy their different carb as well? Silencer Useless? Timing out?  No thanks.  Junk. Your short 'review' is not exactly positive. Edited By Mark Powell 2 on 03/09/2012 08:57:18 Edited By Mark Powell 2 on 03/09/2012 08:59:03

It is not just spars..... Centre wing joint. If, as is often done, there is a 1/8 ply (say) wing joiner, discard it. Instead, put a 1/16 one at the front of the spar and another at the back. Make the end of the front one two ribs out, and the rear one four ribs out. This avoids a suddent stress concentration. Note the rear is longer than the front. In a crash the wing tries to move forwards, but is secured at the centre. More stress on the rear of the spar than the front. Double up the rear joiner for a couple of inches. Use no other than Araldite 'Precision' 24 hour epoxy for the spar/ply joint. All other epoxies go like toffee after a year or so and some, Devcon especially, are brittle right from the start. Always taper the spar, less weight at the tips, less inertia, 'distributed' strength, more manoevrability. Use thinner ribs as you move towards the tips, 1/8, 3/32, 1/16. Taper the TE width. I have done all this on an 80 inch high aspect ratio (that's efficient too) 'hotliner'. It is the fastest thing on the field. stays up for more than an hour on a good day, with only 6 or 7 minutes of motor, rolls faster than the eye can see, and you can pull full up elevator after a 180 mph (measured) vertical dive without anything breaking, and it is ten years old. The wings are an open structure, with a D-box LE, tapered spruce spars on the surface, web between the spars not glued to the sides, etc., covered with clear yellow Profilm. The flaperon joint is sealed. Edited By Mark Powell 2 on 03/09/2012 06:06:41

kc, The 3/8 x 1/8 laid flat is more structurally efficient, tapered or not. My reduction in cross sectional area is deliberate. Weight saved already, even without tapering. Glueing spar webs on the side relies much more on the glue. it also uses, in the case of two 1/4 square spars, 1/2 inch more wood. Heavier. 'I recommend....forget tapering'. We are looking for 'better', not just 'adequate'. Cartwheels - they are made to fly, not to crash   Heavier planes crash harder than light ones, that is why small planes are more crash resistant than big ones. Heavy extremities, such as tips, produce more strain on central parts, such as wing joints. Peter, That is a good way too and easier than trying to get a straight taper with one piece. Though I have never done it. Yet. None of this matters on 'day to day' planes (probably why they are day to day), but on 'difficult' subjects like EDFs, weight saving, and large gliders, structural efficiency, can make a big difference. if carried out everywhere. Also weight saving at the extremities increases manoeverabilty. Edited By Mark Powell 2 on 03/09/2012 04:55:32 Edited By Mark Powell 2 on 03/09/2012 04:55:56 Edited By Mark Powell 2 on 03/09/2012 05:03:26

Chris, Yes I have. I thought my resurrection of my Great Planes OS 91 Little Tony pylon racer was clever. Your effort left me standing! Luckily for my wallet they have not got the ARTF Comet in my LMS! They did once but I resisted it.  I presume the 'Tiger Moth' guy bought it. That's how I ended up with the Little Tony. Edited By Mark Powell 2 on 02/09/2012 17:55:24

MikeS, Reversing the plus and minus on a servo lead will simply result in its destruction. Possibly the receiver and battery as well. Thats's why the servo plus is in the middle, so you cant accidentally do it.

Simon, Further, you say 'sufficient strength'. I crash models quite often. People have commented both on my not brilliant piloting (I have somewhat 'monocular' vision, thought it does not seem to bother me anywhere else) and how my models resist crashes. Yet they weigh no more than anyone else's. BTW - cutting lightening holes everywhere, as Chris Golds does in his otherwise excellent plans, saves amazing little weight. I even weighed these 'holes' on my 7 lb EDF CG Swift. Three quarters of an ounce

Simon, Because I read that the two spars should be as far apart as possible (which makes sense), so using 3/8 x 1/8 rather than 1/4 square is good, and tapering accurately my way, rather than ending with 3/8 x 1/16 at the tip  and 3/8 x 3/32 in the middle is a lot easier. Steel girders always have the outside laid flat. Edited By Mark Powell 2 on 02/09/2012 17:12:10 Edited By Mark Powell 2 on 02/09/2012 17:15:51

That's interesting. Mine go the other way, the bottom blades go towards the fuselage. I will swap them round and try. I set up two mixers so I can chop one engine or the other to see what happens. Encouraged by what you just said I might finally have the bottle to try it. High up! (First twin I have ever made. DH88 is maybe not the best choice.) BTW - the only ARTF like yours I have seen was a guy where I fly. He if more used to big Tiger Moths and the like. Pulled full up elevator on maiden take off for some reason and held it. Total end of Comet.

Torque/propwash. (I am never really sure what it it is), Made a HUGE difference to my slightly smaller DH88 Comet twin. Did a tight flat turn and then hit the ground (fairly gently) every time before I put opposite rotating props on. Straight as a die since. I suggest you make both the motors on one side go the same way, and the opposite side go the other way. Otherwise the airflows get somewhat 'confused'. Prop tips moving upwards on the inside (nearer the fuselage) is what I did, after some thought.

Piers, My 'bus driver' comment was about 'paying attention all the time' (though some of them don't) - my garden wall facing a T-junction, once demonstrated that), not about skills. I thought that was clear, but maybe it wasn't. Degrees of boredom/waiting. I only ever did it 'casually' excepting the target practice (they missed!) and the jockeys. everything else was, and is, local. So it was usually 5pm. Even the target stuff was from Hurn, only 15 miles from where I live. The small flying school is 15 miles the other way. The salmon fishing on the Thurso is very good value  Cheers Edited By Mark Powell 2 on 02/09/2012 13:06:41

Not very useful if you don't tell us what kit it is I can give you a bad one, a mediocre one, and a good one, but you have not asked, so I won't

BEB is right. It is 'off topic', but that often happens and it is not discourteous. Though I am gather that others have become so. I use both, as I have said. My opinion? Probably, but not in my lifetime. And I don't think I will worry about it too much afterwards. It is notable that OS is hedging its bets. PS: The original title, I am sure inintentionally, could raise pro and con views. I notice that BEB paraphrased the title into something less of a leading question Edited By Mark Powell 2 on 02/09/2012 10:31:45

Alan, Thanks. No. Whisky, Hopback Brewery 'Summer Lightning', and Merlot. Don't know what a 744 is. Perhaps the cargo one with less windows and a big door?

GREAT GREAT GREAT !!!! So pleased. Now you have sorted it for us I will will open my Hangar 9 box

Turbycat/Piers/Original poster I did the same as the others, but was never interested in an ATPL. Still do a bit of light aircraft instruction, and also on the terrific C42 microlight. Ferry jockeys around in a light twin (that's what all those planes you see on a racecourse do) and sometimes a cameraman for the local TV company for airborne shots. Parachutists. Great. Much more iinteresting than an airliner. Varied. And you get home at five every night. Flown a Lear often a long time ago, acting as a target for the RAF. Have 'unofficially' flown a 747 a couple of times.. Won't say how. My 'real' job has always been computers. Go for a CPL. Need not be expensive from a PPL Having got that, then think about an ATPL. Or try helis. Lots of jobs there. Love the Turbulent. I envy you. Never flown one. I have an old Aeromodeller Annual with an article on building one, by Marcel Druine himself. But we were only apprentices and couldn't afford it. Stay away from the 'Florida' courses. They don't get the weather and our varied environment. Edited By Mark Powell 2 on 02/09/2012 07:51:28

C Norton, I'm not the 'Mark' you replied to. I couldn't agree more. It's not you lot, you are terrific. I'm around Southampton all the time. Plus Middle Wallop and Boscombe Down. The military ATC is astoundingly good. It's the CAA and all the rest continually extending the restrictions. Just look at the Southern chart of (say) 1975 with todays chart. Nuts. And then all this 'Olymipic' garbage. Even Weymouth, and toy planes. And all so poor people who can't afford their own planes, and are stuck with the airborne 'buses', can go on cheap holidays As I said it's not you, its the CAA, Cronies Against Aviation (who are desperately trying to retain 'power' as the new EU authority looms. Like Customs tried to do, and failed). I wouldn't want an ATPL ever. Just bus drivers. Boring. Driving a bus is harder, they have to pay attention ALL the time. Mark (CPL, not ATPL. The CPL was just a sideline to my real job too, just fly for fun now. And the 'CAA bureaucrats' hate us doing it.) Edited By Mark Powell 2 on 02/09/2012 06:40:00 Edited By Mark Powell 2 on 02/09/2012 06:48:11

You usually have to go, young, to an airline. (I assume you mean an Air Transport licence, not ferrying Jockeys around in a light twin). They like to do their own instruction, or though the large commercial schools under contract, with 'fresh' people. You CAN get an ATPL yoursef. Cost at least £100,000. But your chances of getting an airline job with it are low. Keeping it 'current' with no such job is difficult.

fly boy3 Modern versus old. I have thought about this too. But looking at the KK Falcon thread, 90 inches or so span, flies fine on a four stroke 50 or less. Others are similar. Today a lot are designed for build simplicity, by ourselves or the 'Asians'.Straight wings, square tips, etc. And a lot of sheet construction which makes them heavy, and no stronger. Few can be bothered to build up a tailplane. Quick results versus performance. Even the relatively crude and 'budget' late 1940's KK Junior 60 is a revelation. And a typical modern 'real' light aircraft has an inferior performance to a WW1 SE5. And it is not due to 2 or 4 people rather than one. But that is another issue.

These WW2 warbirds are funny. I've got a Topflite Spitfire. Very curvy and 'pretty'. Then you put the two big cannons on the wing. Its whole demeanour changes. Aggressive and threatening, not pretty at all. My wife doesn't like it. (She is having counselling.)

Ducati. Yes. 916 was the best bike I every had. Currently a friend is trying to sell me his 8 month old, 7000 mile V8 Maserati. 'Cheap'. His wife wants a bigger house. Makes a lovely noise, its not electric.

For a four stroke I go for 50 percent bigger than a two stroke, as a rough rule of thumb. OS every time, other than below. Though as far as I have have seen, OS 'superiority' is not by much. The 'CD' RCV engines are good, and cowling is easy, on a Spitfire and the like, as they are not as tall as the rest. Sound a bit rattly at tickover. Don't bother with the 'longitudinal' ones.