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The Wright Stuff

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Everything posted by The Wright Stuff

  1. D'Oh. It took me 10 days to notice this comp. Better late than never, I hope. Yes please!
  2. No Steve. I didn't see the need to. On my model at least, they seemed quite robust. I've had no problems so far...but then I don't fly particularly aggressively. If you stick with the stock 3S set up, and fly in a scale manner, you should be fine!
  3. Hi Steve, Thanks for your interest, and good luck with the repaint - make sure you post some photos when you've done!!! I used Revell 68 for the green, Humbrol 106 dark grey for the upper surfaces, and Humbrol 64 light grey underneath. Standard late war colour scheme for operations over the channel!
  4. Posted by kc on 06/10/2020 14:17:14: The fact is people in Britain are worse than they were in the 50's 60's Nobody ever had their identity stolen and their bank accounts raided in that era! Look on the bright side: highway robbery crime by masked horsemen is way down on what it used to be...
  5. I suppose these days, it should be "one person went to mow..."
  6. Posted by Doc Marten on 06/10/2020 11:30:58: It's when things happen that shouldn't that they are posted and highlighted, those type of posts are on the increase. But that's my point - increase in the posts does NOT necessarily imply an increase in the proportion of dishonest people. It could be because there are more transactions in total. It could be because people are more likely to report it than before. Of course, it could be because people are less honest, but we can't conclude that from this observation alone!
  7. Thanks, brokenenglish, Yes, I agree of course - it's an easy beginner's model and I've flown it many times. I was just using it as an example in this case to experiment with cgCalc, and illustrate my rant about the incorrect manual value! But I stand by my OP - a bad value for the C of G in the manual is literally worse than useless, because it would be better to not state a value at all, than to state one so far out...
  8. Posted by Peter Miller on 06/10/2020 08:35:30: I am sorry to say that there are definitely a lot more dishonest people out there now...or possibly in this day and age there is far more scope to be dishonest . Is that really true, though, or is media and communication better now, which means that we tend to hear about a much higher proportion of the dishonest acts? Society is based on the vast vast majority of people being honest. I don't think it would even be worth getting out of bed in the morning if that wasn't the case... There's a selection effect, right? No-one ever starts a thread on here stating: "I posted an item and the chap received it and paid me and there were no problems and we all lived happily ever after"... but yet the vast majority of transactions - thousands every day - are trouble free and with honest people...
  9. OK, so going back to the Night Walrus example. I took the advice and used cgCalc to estimate the C of G position based on the geometry. It was a bit rough and ready - using two trapezoids for the wing and tail section. The result for a static margin of 15-10% is 84 to 92 mm back from the LE. This corresponds to 44% to 49% of the chord at the root). Wow. Given the wing is only slightly swept, that's much further back than I expected. I'm not sure if I completely believe this - this is much further back than for most models cited as 'typical', and way further back than the 71 mm stated in the manual. I guess the model may be regarded as slightly unusual in that the tail-plane is pretty far back - behind the fin. I may of course, just be overthinking this. The irony is that if I'd just ignored the manual and built it stock, stuck in a battery and gormlessly chucked it, it would have flown just fine!!! It's clear that I can be confident in moving back the C of G in stages, and test flying each time.
  10. Posted by Zflyer on 01/10/2020 22:16:35: I have HK walrus and Night Walrus and didnt have any problem with c of g as I recall, but will check over weekend as they are both my ladies . In any event they are cracking to fly. Hello Zflyer, My OP was a general rant, but I'd love to take advice regarding the Night Walrus specifically. With the same 2200 mAh Turnigy 3S shown in the manual, I found I had to add 40g behind the motor mount in order to get it to balance according to the instructions. It would be good to know where yours balances when trimmed... Did you add any down-thrust to the motor? It's been a while since I flew a glider - most of my recent maidens have been low wing sports models. Trimming elevator for power off glide is a slightly different technique than I'm used to! Cheers in advance for advice! TWS
  11. Posted by Peter Miller on 02/10/2020 09:11:22: THis has been said on this forum and many times elsewhere "With the CG too far forwards the model will fly badly. With the CG to far back it will fly ONCE" I use a CG located at 25% wing chord on mmy designs. Edited By Peter Miller on 02/10/2020 09:12:31 Thanks Peter, as you say, it's been said many times and I appreciate the take-home-message that a margin of safety is represented by a slightly forward C of G. However, let me ask you this. Who is responsible providing that margin? The designer, or the builder? Or put it another way, you design a plane, and indicate a C of G on the plan, either from 25% or from calculations. Do you consider that to already contain a margin (degree of safety by being slightly forward), or should I add it myself by starting with the C of G slightly forward of your marked position? Thanks everyone for responding! TWS
  12. I'm currently wondering how conservative ARTF manufacturers are when they specify the centre of gravity position in the instructions, or mark it on a plan. Is it deliberately too far forward to make it 'more forgiving' for beginners? Perhaps there are some designers on here who can comment? I'm currently fettling a HK Night Walrus (taking advantage of the darker evenings), but here is how my last four builds have gone: Assemble aircraft according to the build plans/instructions. Mark the recommended balance point on model wing with a permanent marker 'dot'. With battery installed, balance the model on fingertips with battery as far forward as it will go. Find it is tail heavy. Spend the next two weeks trying to carve out the inside of the nose cone in order to make room to stuff lead. The model now balances level when suspended on the marked points. Fly the model. Find I need arm loads of up elevator trim to maintain level flight. Aircraft then swoops up out of a dive test, and porpoises horribly when slowing it down. Climbs like a homesick angel on half throttle. Land. Find the elevator is 5 mm up from the centre line of the tail-plane. Take all of the lead back out of the nose again. The model now trims nicely, but with the centre of gravity 10 mm behind the marked points. Unless I am completely missing something, I can only assume that many model manufacturers or designers want me to start off with the CofG in a 'safe' place (i.e. forward of the ideal position). It could be the way I measure it, or the way I fly. Does anyone else suffer from this, or (to quote the late Mr Wogan): is it me???
  13. Does this help? This is a few years old, but may still be relevant...
  14. Posted by Steve Houghton 1 on 14/08/2020 13:54:52: Someone once told me that high wing aircraft require down elevator compensation and low wing aircraft require up elevator compensation. How true that is I don't know as I don't have any low wingers with flaps. That would certainly make sense for models where the drag force is dominant over additional lift. If the additional drag caused by the flaps is above the CG, then it would tend to pitch up, requiring down elevator. And vice versa...
  15. With the exception of the requirements for jet turbines, I can't see that an investment in a fire extinguisher for the flight line is all that useful. For clothing fires, I would say water and/or a fire blanket would be better, more reliable and less maintenance... For Lipo fires, a bucket of sand.  For anything else. Let it either burn itself out, or get the experts there... Edited By The Wright Stuff on 15/02/2019 08:34:25
  16. I think one overlooked point of comparison is flying habits, proximity to your site, and available time. I fly both I.C. and electric. If I'm spending the whole day at the club, I'll take I.C. If I am stopping on the way home from work for a quick flight, I'll take electric. I personally think the causes of prop accidents from I.C. versus electric are so different you can't really say one is safer than the other. The precautions you take are specific to either discipline...
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