Shaunie

I have been given a Centra CUK 2402 transmitter, it's had about 3 minutes of flying time which was how long it took a friend of mine to lose the heli he was trying to fly with it (I know where it is to within 20metres or so but after hours of looking and finding bits of rotor blade, no luck). My question is this, Is there a compatible receiver available for sensible money so I can make use of it for a parkflyer (fixed wing). Seems a shame to use it as a doorstop. The trouble as I see it is that many of these 2.4GHz sets use proprietry protocols so I very much doubt that an Orange receiver will be any good. Shaun

Just to add my tuppence worth. First off I am not a lover of snakes, preferring to use a closed loop setup if possible. Local servos with short pushrods must by definition give the best fidelity of control surface movement for servo operation but I do think them unsightly. Also sticking three servos in a tailplane is poor for CG and longitudinal moment of inertia reasons IMHO. However, back to snakes. By way of visualisation:- Bowden cables used for throttles,clutches etc.work only under tension, however similar systems used for steering on boat outboards and gear mechanisms in many vehicles are similar to snakes, working in push-pull. In many instances there is no rigid link (the fuselage in our application) between the two ends of the outer, thus the load on the outer is the direct inverse of that on the inner as result the inner compresses and the outer must stretch, to combat this the core and outer are usually metallic. Transfer this image to a model:- When a snake is loaded with the inner in compression the outer therefore will try to stretch, as its ends cannot move it will achieve this by bowing in the middle. Imagine a "perfect" snake with no sideplay and zero coefficient of elasticity it would be unnecessary to support it midway and there would be no loss of movement. In the real world however there is sideplay, this results in buckling of the inner under compression, a sideforce is generated on the outer which then gives the initial sideforce to start the bowing. This bowing then is caused by a net difference in movement between the input signal and the output one. It seems to me that the more constrained the outer is to remain in a straight line the smaller this effect will be, effectively the outer is only strengthened by the fuselage if it is constrained so as not to be able to move at all. The big question is whether in the real world this is big enough to be a problem. It seems to me, keep your snakes straight and support them as much as possible. One downside of plastic snakes I found on one model was a huge variation in trim due to expansion and contraction brought about by temperature changes. Before every flight I had to eyeball the rudder and elevator neutrals because I could never be sure where the trim would be. Shaun

Hi Rob, On one occasion when I couldn't get a tank to fit I made one out of sheet steel from an old 5 litre oil can, easier to make than you would think. Two square end caps with a small lip tapped over right round and one strip formed into a square tube all soldered together. Nicked a clunk from an old tank and a bit of silicon pipe withstood the soldering ok. Still got it somewhere, I'll see if I can post a pic. It was about 6 ounces capacity and it was not very heavy (little bit more than a comparable plastic one but not much). To correct the height difference is it possible to invert the engine (sorry can't see your sketch, it no longer displays). Shaun.

Hi Guys, There is a knack to crimping connections, been making crimps professionally for over 30 years (getting old or what!). At the last count I had 17 pairs for different jobs and I still get caught out not having a pair for a job from time to time. Quality crimpers are very expensive £75-£100 is not unusual. Chinese/Taiwanese crimpers do get them in reach of occasional users but quality does vary considerably, as does the competence of the user. The very small size of servo connectors does not make it any easier. Practice makes perfect. Good quality crimpers will be made specifically to suit the terminal in question and the jaw pockets and anvil will look as if they have a ground finish. Cheap crimpers will look as if they are pressed or formed. Crimpers do tend to run-in as the terminals burnish the jaw giving an improvement in quality. Ratchet crimpers are better than non-ratchet for many reasons, the main one was to ensure that the jaws were fully closed when making the crimp and thus avoiding a partially crimped connection. For the best quality termination the crimp needs to be formed fairly quickly in one smooth movement so that the ears of the crimp get a chance to flow continuously, no stopping for a look halfway through the process. Crimp terminals closed with pliers are not proper crimps, there is insufficent force to form what is virtually a cold weld when the crimp is properly made. In this case please solder them as well. As already mentioned, soldered joints are more brittle and less reliable than crimp connections. A crimp has better vibration resistance. When soldered the solder can wick up the wire if not performed quickly this makes the wire rigid and liable to break up inside the insulation where it cannot be seen. There is also a risk of filling the crimp with solder rendering it useless. A couple of final points:- Never tin the wire end with solder before crimping (or put it in a screw terminal for that matter) it will always come loose. Never double the conductor back over the insulation to fill the crimp better, this causes the conductor to break inside the insulation. it is ok however to double the conductor over itself to fill the crimp more fully if the wire is a bit small for the termination size. Final analysis, solder if you have to but crimp is better. Hope this is of use to someone and that I haven't waffled too long.

Hi Tim, I agree with all you say but the servo behaviour was definitely different after binding for the second time. When I finally get round to building something with retracts I will definitely fit a second battery pack with its own power switch. Just performed a test, if the servos are manually moved to off-centre positions with the power off, when the Rx is powered on they immediately centre even with the Tx off. I seem to remember that prior to the second bind that the servos on the aux channels went to different positions and adopted their correct positions after the signal was picked up from the Tx. Perhaps its just the neutral positions that are stored. Tried turning the Tx off with control inputs set and they remained where they were, confirming the lack of failsafe on all channels. Shaun.

Just a little bit to add to the info:- Just set up an AR7000 into an Seagull Edge 540. I performed a bind on the receiver and then set up the mixes for the additional elevator and aileron servos (on Aux1 and Aux2). Whenever the receiver was powered up the servos for the mixed channels would kick to odd positions and when the signal was picked up from the transmitter they would then adopt a normal position. After a re-bind they behaved normally. It seems to me that when a bind is performed that the mix setting is stored in the receiver. I didn't make a specific note of the behaviour so this is from memory but it should be easy enough to reproduce if anybody wishes too! Shaun.

Hi Guys, Not familiar with the aircraft but, with my understanding of aerodynamics although the higher outside wing on a turn is going faster than the inside wing it is also at a higher angle of attack due to the attitude of the aircraft. It also has a downward deflection on the aileron both of which can promote a stall in the higher wing causing a sudden (unexpected) wing drop. I know it caught me out a couple of times when first learning to fly, I complained to my instructor something was wrong with the plane to which his reply was along the lines of "nothing wrong with the plane, it's the pilot, you let the plane slow up too much". This was a PrecedentHi-Boy trainer. Just wondering if a bit of local turbulence added to this effect may have been responsible. Shaun.

I usually start all my engines with the method shown in that clip BEB posted, twostrokes included. No putting your figer in the prop and no bending things with the electric starter either Shaun

Nice one Kevin, I think our piloting skills are on a Par! Started a conversion on a Danarm Chainsaw motor (about 46cc IIRC) about 20 years ago, never got it finished I made complete front crankcase half and prop driver never got the engine mount and ignition system done. Still got most of the bits somewhere. Times have moved on, engines of this size are freely available now but weren't then. Shaun

Sorry Steve, I think you missed the passed tense of my statement the stuff got used up years ago and I never could find any more. I was younger then and could remember the product name now unfortunately I can't, I was hoping to prompt someone else's memory. I do remember cleaning up my engines (pre-synthetic days I would think) and they came up looking brand new. Shaun.

Here's my tuppence worth. I don't believe the lock nut system on fourstrokes is there to keep the prop tight, ultimately I think it is there to keep the prop ON. I too have seen a fourstroke throw its prop off. Early O.S 61 FS if I remember correctly. Reminds me of the real reason why we use spinners, it's somewhere to find the prop nut when this happens. I would rather the prop came loose if the engine kicks back rather damage the engine. I feel that the cause of engine kick-back is ultimately an operator error, good mixture control should almost completely prevent it occurring. The problem is that there is a danger point at both ends of the mixture window, detonation if excessively lean and the twin spectres of pre-ignition and hydraulic lock at the rich end. Excessively rich mixture reduces headspace at TDC due to incompressibilty of the fuel this increases effective compression which will advance the ignition point and as a result cause pre-ignition. Personally I am not a fan of excessively rich mixtures for running-in, a couple of clicks maybe and then manage the heat build up by sympathetic throttle handling. Another point that has not been discussed here is starting method. I have an O.S 40 FS (which is the only FS I am using at the moment) but I never put an electric conrod bender on it. I prime the engine until it is nicely wet and floppy turn it anti-clockwise until I feel compression then smartly snap the engine over backwards by flicking the spinner, rather like snapping your fingers. Get it right and the engine just bumps into compression backwards, backfires, changes direction and promptly starts itself! I use this method on two strokes too. I have just run-in a TT Pro 46, primed it up and started first flick using this method from brand new. The only time I ever put my finger through the prop is priming. The only proviso is it does not work well on tired (or very hot) engines. Shaun

Bought a cleaning product (from a model show, I think) many years ago. It seemed to be a mix of Methylene Chloride (paint stripper) and Ammonia. Worked really well, unfortunately my memory lets me down on the name. Don't think it's possible to buy ammonia over the counter now to try making my own brew. I have a Super Tigre 61K that I would like to restore and would love to get it spotless before rebuilding it. Might try the antifreeze trick. Shaun.

Thank you Ken, Will try to get some photos uploaded when I get a chance, just took a look through your albums. Forgot to mention, Precedent HiBoy, back in the air, built in 1985 last flown 1991 I think. It did get new batteries and a new set of servos though. Shaun

Hi Ian, I'm new here too, but not new to building although I have had a loooong break. Here's my advice. Break your building project into manageable chunks (I don't mean literally ), obviously you need to keep a general idea of the big picture but if you look at the whole aircraft build as one item you will never seem to make headway. Pick a part of the build you can reasonably finish in one session, maybe build the fin, shape a set of ribs, whatever, so that you can finish up with a sense of satisfaction that the project is a little farther forward. Very soon all the small steps will add up to a noticeable level of progress. Also if it's not going well, stop building and watch the telly, carry on another day. Other wise you will either wreck something or leave yourself something you will have to try and dismantle to put right when the glue has well and truly gone off! When I was a young and single fanatic I used to reckon a sport model (40-60 size) took me six weeks of every spare moment to build, 2 for the airframe, 2 for the covering and 2 for the engine/radio fit, although I did think I was quite a bit more fussy than some of my friends. Good luck with building. Shaun

Hi All, Just picking it back up after a 16 year break. Stopped when the kids started to come along. Now they are saying "why did you stop flying Dad". "'Cos I've been too busy taking you to Cadets,boyfriends, shopping etc." Dusted off the Dare-U (think that's the spelling). Designated extreme aerobatics as 3D hadn't been invented in the early 90's. Built it with an O.S 40 FS in the front which was fine if you wanted to potter about, but was always a bit disappointed with it for it's lack of power. To cut along story short (too late you say!) a good friend of mine bought loads of gear intending to take flying back up again, moved out of the unit next door to me at work and decided that flying was something he was not going to do after all. He gave me a Seagull Edge 540 (68 inch) set up for electric power,a brand new Spektrum Dx7 with two AR7000's, an unflown Thunder Tiger OBL40 trainer with brand new Thunder Tiger Pro 46 engine, a Topflite Spitfire kit with retracts, RCV90, wheels tank etc. and a Graupner flight box with all the accessories. Thank you Darryl you really are a top bloke. The TT 46 found it's way into the Dare-U, that's more like it, straight up on anything over half throttle. All I've got to do now is learn how to fly it again. Left off at the sport aerobatic level really, got reasonably comfortable with inverted circuits, trying my hand at knife edge etc. Now an inverted circuit practically brings me out in a sweat. Just need to get plenty of stick time in. Bought a Vortex 400 a couple of weeks ago, seems to be more plane than I am pilot, great fun in the air but I fly from an un-mown field and it seems to be hard to flare it for landing, the last one was a greaser or so I thought, Just caught a couple of long grass stalks and over she went, ripping off both ailerons in the process. Add expletive of choice here. Eldest Son has expressed a desire to build the Spitfire (not interested in flying it, just wants the build) He's very good at Warhammer 40,000 type models so I have no doubt it will be beautifully detailed. The Edge has it's own problems which I will post in the appropriate forums at some time, but it does fly. I'll stop there for the moment Shaun.

I'm using XP and IE8 and unable to post, if you are read this the compatability view button has worked for me. Shaun