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Martin Harris - Moderator

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Everything posted by Martin Harris - Moderator

  1. Martin Harris - Moderator
    That'll be the reason!  Actually, that was the result of a mid-air on its second outing.  Things would have been OK if the other model's prop hadn't cut the aerial an inch from the receiver!   Having enjoyed it so much, I had it in the air again a week or so later - believe it or not it was a lot less serious than the picture makes out.   Better let this thread get back to model pilots soon or we'll be in trouble!
  2. Martin Harris - Moderator
    Phil wrote martin i have one of these to build do they have any vices thank you They don't enjoy mid-airs but it rebuilt OK.   I've acquired an Extra Slim kit and have got as far as cutting out the duplicate fuselage parts I'll need.  I'm planning on building it with removable wing panels this time and upping the span a little to reduce the wing loading with the 46FXs I'm planning to use this time.  The first one started on SC25s and ended up with 40FPs and excellent vertical performance so I'm expecting phenomenal performance if I can get it through our noise checks with suitable props.    It needs some rudder applying on one engine but is great for learning to handle asymmetric thrust. If you lose an engine - it's up to you whether you land or just continue on one engine for fun.   Repertoire is more or less unlimited.  Knife edge is as good as you'd imagine with 2 profile fuselages.   The reason I'm having to build another is that mine suffered an engine out in a flat spin at @ 30 feet and I didn't realise why it wouldn't recover until it was at minus 6 inches.   I think you'll gather that I'm strongly recommending it!  The only vice is that it's addictive...
  3. Martin Harris - Moderator

    Martin Harris - Moderator posted a gallery image in Member Albums

  4. Martin Harris - Moderator
    Chessiegolf,   That's certainly established your credentials!   I'll be very interested in your findings.  Of course, all models behave differently but whatever yours does will act as an indication - what is it youre building?   Have you done any experiments with thrust lines adjusted to provide some help?   Modern full size practice is to hold a little bank into the live engine and apparently they don't teach you not to turn into the dead engine any more - but I suppose modern designs have had a lot of development into better engine out characteristics.
  5. Martin Harris - Moderator
    Just thought - I'll be in trouble now with the moderators for using a dirty word disguised with asterisks....
  6. Martin Harris - Moderator
    P.S. B.C. showed me how to do it far too many years ago so I'm a Mode 2 thumber as well.   I do admit to having used finger and thumbs and a neckstrap when I flirted with h*l*c*pt*rs a while back but I've had therapy and I'm on the road to recovery!
  7. Martin Harris - Moderator
    As opposed to an improper mode 1?
  8. Martin Harris - Moderator
    Some authenticated historical information (I used to watch it every week!)   Dick Dastardly and Muttley flew in the Vulture Squadron but had their own aircraft although occasionally for some missions would double up. Their main aim was to catch the heroic carrier pigeon.   Dick was always put in a perilous position via one of his nefarious schemes and Muttley would come to the rescue, after negotiating the award of another medal.  I think I remember him using his tail as a helicopter rotor on more than one occasion.   In the Wacky Races, Dick and Muttley did share a car.   In later years, they progressed to an Extra Slim Twin  
  9. Martin Harris - Moderator
    Chessiegolf,   From your mail you seem to have some twin experience and I must admit that the majority of mine has been on a model that laughed in the face of asymmetry!  In fact, on its maiden flight (and my first twin experience) it lost an engine while I was trimming it and once I'd worked out that the non-revolving prop was the reason for its odd flying characteristics, found it easy enough to land for a relight.   Have you actually tried a gyro in roll on a twin?  I'd be interested to know if it behaved as you have outlined - certainly, my gut feeling is against it in principle but if it has been proved to work well (particularky in an engine out at rotation scenario) then I'd be delighted to be educated.   I do recall watching an electric Hornet suffering an electric motor failure during a high speed pass, but my impression was that although it rolled it was a flick roll - which might not have responded to aileron depending on the model.  On a couple of occasions, I've experienced inadvertent flick rolls on small combat models (no rudders) due to streamer cuts on wingtips which wouldn't respond to opposite aileron at all.
  10. Martin Harris - Moderator
    I've used this nomograph method - published in BMFA news a few years ago but I've found a link here:   http://www.smithymac.org.uk/html/c_of_g.html   ...and found it's worked well for me with some own designs and to check plans where I wasn't too confident of the published C of G.   I understand that all you need to do for a biplane is superimpose the top and bottom wings and use the "shadow" of the pair as a single wing in the calculations - although I haven't tried this.
  11. Martin Harris - Moderator
    As I read it, if it's at a BMFA affiliated club, then under BMFA rules, both will have to be BMFA members after the introductory sessions.  If not, the club would be in breach of its affiliation, putting at risk those aspects of the BMFA insurance pertaining to the club as a whole.
  12. Martin Harris - Moderator
    Just to confirm your understanding, think of the power transmitted by National Grid power lines - measured in Megawatts - this is the reason they run at 400 000 Volts.  100 Megawatts equates to only only 250 A (a heavy arc welding current) at 400KV as opposed to 5000A at 20KV which would need ridiculously heavy cables.   As losses due to heating increase by the square of the current, you can appreciate the wasted power involved at lower voltages.
  13. Martin Harris - Moderator
    Good post which gives a lot of very important advice.  The one thing I'm not sure about, though, is using the gyro to pick up a wing.   I think that the typical crash scenario is that an engine dies, a yaw is induced giving some roll couple.  The ailerons are used to counteract this and hopefully the pilot is capable of inputting some rudder, but more often than not the ailerons are overused.  A climb to safety height is commenced, airspeed drops off and an incipient stall is exacerbated by the wash in effect of the aileron, leading to a wing drop.  Instinct (or learned response) kicks in and more aileron is input to raise the dropping wing, while the rudder input is forgotten and the model spins.   Wouldn't the gyro simply attempt the same thing?
  14. Martin Harris - Moderator
    Agreed, but my point was that your "solution" is not a guarantee of drama-free flight - good airmanship is to anticipate the ever possible eventuality of an asymmetric power situation.   As my current build is an electric Mosquito I'm certainly not against the idea...
  15. Martin Harris - Moderator
    At a hundred yards and 300 feet high I have a strong belief not many can tell if the doll in the cockpit looks realistic or like ScoobydooTEST   I agree without question, but at twenty yards and 5 feet high where I am fond of flying a scale model, I have a strong belief that an aircraft with an empty cockpit looks like an elephant with no trunk!!!
  16. Martin Harris - Moderator
    Whoops, while I was aware that the majority of Hawks had dry engines, I'd got the idea in my head that some later operational versions were fitted with reheat.  I think I must have got confused by the fact that Adours are available in reheat versions...   P.S. As the Nijhuis Hawk is only "cartoon" scale, I think I'm OK to call it an experimental development version to investigate the suitability of fitting an Adour Mk 811?
  17. Martin Harris - Moderator
    Well, if I was building a Queen Bee there wouldn't be anyone in residence but the thought of a Tiger Moth under the control of the invisible man is ridiculous to me.    To those who say a scale model is spoilt by the non-realism of a bit of stuffed rag and plastic, why don't they take him (or her) out while it's parked between flights - after all, that's what usually happens in the real world!   P.S. Wasn't there once a case of a Moth of some type taking off without the pilot (solo hand swinging and had left the throttle open if I remember the story correctly) which took off and landed many miles away without being damaged?  You could duplicate this flight without a pilot figure on board I suppose, but there'd be a long walk involved!   P.P.S. When will most people start putting solo pilots in the REAR seat of Piper Cubs? (Super Cubs excepted)  Nearly as bad as no-one at all!
  18. Martin Harris - Moderator
    I was thinking of doing exactly the same with my Nijhuis Hawk (although probably not entirely appropriate to mine in Red Arrows livery) - I've just never got round to it!   I was planning on  switching a number of orange high intensity LEDs located in the tailpipe with an old servo board (or you could use one of the other suggestions as per the thread on "Smoke on the Cheap") as I've already done for a landing light on my Chipmunk.   Hopefully this thread will act as a spur to me to get on with it!   If I do and you haven't already done so, I'll post the results.
  19. Martin Harris - Moderator
    Great idea - but I do recall watching an electric Hornet spin in when a motor seized, so you'd still need to be aware of the possibility of a failure.  Recently, I saw an electric prop shed a blade for no apparent reason.  As most electrics these days are brushless, you could get an ESC fault, a LVC cut-off (especially on a twin battery set-up, a prop being shed, a wiring fault etc. etc. so you still need to bear a motor failure in mind.
  20. Martin Harris - Moderator
    It very much depends on the model.  A heavy Mossie would be a handful with an engine out and a deadstick might well be appropriate but if faced with a risky situation, e.g. over trees, poor landing surface etc. with careful handling it might be more appropriate to get to a safer position on one engine. If you know your model and it has a reasonable layout it shouldn't be a case of almost definitely smashing it as long as you appreciate the need to maintain a good airspeed. However, if in doubt, your advice is very valid.   The other end of the scale is something like the Extra Slim Twin in my avatar - 999 times out of a thousand it will perform brilliantly on one engine - the slab sided fuselages and fins in the slipstream mean it can continue to perform on one engine with a virtually full repertoire of manouevres.   What about the 1 in a thousand?  Try losing the inside engine in a flat spin at 30 feet!
  21. Martin Harris - Moderator
    THIS one is Lettice Curtis
  22. Martin Harris - Moderator
    Action Man is 1/6 scale assuming he's representing a 6 footer and is getting quite used to my Chipmunk
  23. Martin Harris - Moderator
    I've read that it is possible to run 2 on one ESC but inadvisable as the start-up may be in random direction for the second motor.
  24. Martin Harris - Moderator
    OK - time to stop messing around - it's Maureen Dunlop in front of a Fairey Barracuda.
  25. Martin Harris - Moderator
    or Ann Welch (nee Edmonds)?
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