Martin Harris - Moderator
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Posts posted by Martin Harris - Moderator
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An easy question for once!Local rules must take precedence over BMFA guidance (which is what the handbook is - it's not strict rules). The only rules which are compulsory in the handbook are those directly related to the Air Navigation Order - but the ANO is the authority, not the BMFA handbook.As for transmitters on the strip, I take the view that this relates to operating far away from other pilots such that there might be a serious degredation in the strength of the received signal and a danger of interference (a fairly unlikely event?) from a transmitter being operated much closer to the model. The other pilot is likely to still be reasonably close after venturing out to take off.
Edited By Martin Harris on 20/08/2010 01:32:37
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Hand launching has been brought up by a few posters but our normal practice is to ask other pilots for permission to launch and walk out a few paces for the launch. Ground run is. of course, of no concern so launching from mid strip is no problem.
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The factor is applied to the design load e.g. +4 -2 would be tested to fail at more than +6 -3 ... the placard speeds are based on these factors to establish maximum manouvering speeds etc. (although to hit 1.5 times design loads only requires exceeding the placarded speed by 1.22 times)
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Whoops - I meant 2.45V !!!
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Timbo, I'd guess you're not used to pilots standing in front of you at the Big Rock?
Edited By Martin Harris on 19/08/2010 11:58:08
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A lot of sealed lead acid batteries are recommended to be charged at a constant voltage - often around 1.45V per cell. The Pb setting on my GT5 Bantam clone does just that.Otherwise you'd probably be OK at a 10 hour rate.Best bet is to get hold of the manufacturer's data sheet for their recommendations - there are different technologies often described as SLA such as lead/tin with slightly differing recommendations.
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My initial reaction reading David's post was to dismiss it out of hand - after all, the BMFA recommends the pilot's box in the middle of the runway and most videos I've seen from around the world mirror this practice but then I started to think about it and perhaps he does have a point.I've seen plenty of pilots carry on with take-offs when they are pointing at the other pilots in the pilot box and standing behind the model - most seem to abort earlier if it's coming at themselves! I've always taken this as a positive benefit of taking off whilst standing in the pilot's box.Why do we do it this way? Is it just for practicality - have a direct route from the pits to a position in the middle which is useable in at least 2 wind directions? I suppose the other drawback is that a pilot going to or leaving the pilot's box at the threshold is then exposed to danger unless all low level activity is suspended whilst they are in transit unless at a very large site where a route could be taken well clear of the runway.
Edited By Martin Harris on 19/08/2010 11:32:40
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That last incident illustrates the downside of someone rushing through their training - quite competent with the physical control but with little experience of real world complications which the slower pupil will be likely to have encountered in a supervised situation.Time to master the physical "motor response" side, by and large, relates to the age of the pupil - awareness comes more with flying experience and willingness to self-analyse honestly.
Edited By Martin Harris on 19/08/2010 10:09:27
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WOW - I started composing the above when there was one reply - admittedly I was interrupted but I was gobsmacked when I saw how many posts there were!
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I tend to agree with your "friend" that it's much better practice to taxi out and take off from the side and have been teaching people to do it that way from scratch for some time. There are hazards involved when people walk out to take off which are entirely avoidable by staying in the pilot's box. Having said this, we have people who can fly competently but prefer to stand behind the model and we accept this within the club.Although exponents of the standing behind method say it makes it easier for them, by and large, they seem to be the ones who are weakest on rudder control and they often seem to take off in whatever direction the model happens to go in - perhaps standing behind the model gives them the comfort factor that the one place the model will not go is in their own direction? Maybe that's a bit of an unfair generalisation though if it's just that someone was taught that way...Standing at the side allows you to balance a taildragger on its wheels properly and judge the initial climb out angle properly. It may be co-incicence but the majority of badly controlled, hanging on the stall type take off "adventures" that I witness seem to be from pilots standing behind.Finally, some people claim it's difficult to assess the take-off direction from the side - but since when did anyone go to the end of the runway to do a landing approach? Most people seem to cope OK from the pilot's box!It might interest you to know that there is a strong proposal to make taking off from the pilot's box a part of the A test which I believe is likely to be adopted soon.
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The Magnatilla is an excellent choice in my opinion and is a great introduction to tailwheel flying. The 46LA is virtually the same weight as a 40 and not the most powerful engine for its size so should be fine. I regularly fly a friend's one with a Saito 50 and it handles beautifully.Nice to see someone joining the world of "real" building - I always have a wry smile when someone describes their ARTF assembly as a build....
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Which nit was that?
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Most plans/build instructions show quite small rudder movements but full size almost invariably have much more angular deflection.I tend to set the maximum movement to parallel with the inner ends of the elevators on scale models which is usually around 45 degrees either way and the same for fun-fly type models. The one exception is my Panic where the rudder goes as near to 90 degrees either way as I can get it - but it is a silly thing!I can't say I've ever felt the need to reduce the movement and as BEB says, there's always expo. Spins (and recoveries!) are enhanced and the main benefit is in ground handling at taxi speeds.
Edited By Martin Harris on 18/08/2010 23:44:43
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If anyone's interested, I've had a play and a mix for the slider trim control on an FF9 and similar Futaba transmitters can be done as follows:Set an aux channel to use Vr-E (RH slider - I always use the left one for flaps)Set a programmble mix in the advanced menu:Mix ONMAS AUX1 (as appropriate)SLV ELEVLINK OFFSW (any)POSI NULL (you can use a switch to disable the facility if you wish - set direction here)L HRATE -10 -10 (amount as appropriate + or - controls the direction the slider goes)OFFSET + 50% (move the slider to the neutral position and press select)The slider can then be used as an elevator trimmer up and down - if you only want to trim elevator up, set the offset at +100Weather permitting, I'll try it out tomorrow...
Edited By Martin Harris on 18/08/2010 21:22:37
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I can't really agree here, Andy although you do make some good points about learning to fly without too many artificial aids As I understand Tony's original post, he's been in the habit of re-trimming for the landing approach, which is standard practice on almost all full size aircraft, using his old fashioned slider trims and Tony has recognised the limitation of standard digital trims in achieving this. In my opinion it's a good thing to do.If you watch the majority of club fliers, the approach is flown far too fast (unless they're a bit low and stretching the glide instead of adding power) because laziness or unawareness prevents them from holding the correct attitude (and therefore airspeed). Then they wonder why the model floats off the end of the patch after flaring at the other end!!
Edited By Martin Harris on 18/08/2010 20:04:16
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Ask your instructor!I'm afraid asking this question on a forum is akin to asking the length of a piece of string...dead easy if you can see it but there's no (sensible} answer otherwise!Everyone is different - are you off the buddy lead, doing take-offs, landings and practice dead sticks, know the handbook properly, OK with both hand circuits, figure of 8s, fully conversant with good pits procedure and local rules? When you're competent and confident with all these aspects you'll be about ready...
Edited By Martin Harris on 18/08/2010 14:35:40
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The nut should be fully tightened before the grub screw - if you let the grub screw control the nut's position it may not tighten down onto the prop!
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Best set-up is a true parallelogram with the servo arms and horns having equal (effective) lengths and the horn's holes being on the hinge line.Other than a lack of mechanical nicety, as long as the servo arm is shorter than the horn arm then it should all work OK as the "dead" side will slacken. Airflow should prevent any untoward effects in any normal forward flight condition.
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Just a thought - have you got a little rock that you could try it from first?
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I think I'd work on this as a delta and ignore the canard label. I would assume that the canard calculator assumes variable incidence and a more conventional couple? Why not try the calculation as a pure delta incorporating the canard as part of the delta shape?A back of a fag packet graphical method to establish the mean chord (including the canard wing) draws me towards the original position...but that's a very rough guestimate
Edited By Martin Harris on 17/08/2010 14:20:31
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I think you may find that very few model pilots are properly educated to re-trim for various phases of flight and I'm afraid I'm guilty of just holding a bit of back pressure on the approach where appropriate.You've reminded me that I keep meaning to experiment with mixing a slider to allow in-flight trimming on my FF9/FF10 transmitters...What I have done in the past for hand launching combat models is to set a small amount of up trim controlled by a switch to allow me extra time to get back on the elevator after launching (I'm right handed and fly mode 2). There's a delay before the prop "bites" and with the drag of a streamer the first few seconds can be a bit marginal! If your transmitter allows this then you could do the same to a pre-set position for the approach.
Edited By Martin Harris on 17/08/2010 14:06:51
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The dodgy thing is where someone thinks that they'll just bung some nitro into some old fuel to make a "racing" brew. In simple terms, adding 1 1/2 pints of nitro to a gallon of straight 85/15 fuel to mix up some 20ish% would reduce the oil content to around 12.5%
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A clubmate spent some time in hospital having blue foam dust scraped out of his lungs! He'd been doing some extensive sanding of blue foam in his shed.
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My vote's for 7.5 % - it gets trickier if you want to add one component e.g. nitro-methane as the oil and methanol percentages are then changed and it then takes a bit more thought to work out how much oil to add to maintain the same oil percentage.The only other possible complication is if you're using 2 different makes and one measures by weight and the other by volume...P.S. the only other other possible complication is that one fuel may have a different oil which might just conceivably have mixing problems but I don't think that's very likely. Whatever you use, mixing 50/50 will average whatever you've got!e.g. Fuel 1 - 73% Methanol 15% synthetic 2% castor 10% nitroFuel 2 - 80% Methanol 15% synthetic 0% castor 5% nitroMixed Fuel - 76.5% Methanol 15% synthetic 1% castor 7.5% nitroI'll stand by to see what the only other other other complications are that the rest of you can think of!
Edited By Martin Harris on 17/08/2010 11:52:25
Taking Off And Landing
in All Things Model Flying
Posted
Edited By Martin Harris on 20/08/2010 01:57:56