John Bisset
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Posts posted by John Bisset
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So does that mean that the only benefit of undercamber is drag reduction rather than increase in lift ?
I recall some sailplanes designed in the Fifties - like the Slingsby T21 (Sedbergh) which had undercamber. We all thought/believed this was for greater lift at lower airspeeds.
I suppose as a glider, and a slow speed one at that, drag reduction was equally useful, since that presumably means lower sink rates, all else being equal.
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Posted by Cuban8 on 29/08/2019 09:24:42:
Have you actually seen just how much the 'Achievement Scheme' has ballooned (!) since the days of John Long and 'Up and Away'? Not getting into a argument over it, but you can see where it's been heading for some years now.
Cuban8 - this is something I know nothing about, having been away from the hobby for much of the relevant time (I suspect, since my former club did not use any national scheme in the late Eighties) Can you tell me more?
If this is likely to prove controversial in your view, by all means message me privately if you prefer.
John B
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Posted by Jonathan W on 15/08/2019 10:35:04:
All very well, but what is the justification for a 2 NM radius no fly zone? 1/2 mile would have been enough. As it was, not only were people rightly not allowed to fly at the event at the Hoe, nor were they alowed to fly from land across the other side of both the river esturies.
The flyers were probably breaching the normal restrictions of flying in proximity to people & property anyway, without any no fly zone being imposed.
I agree it seems a rather large zone. As a guss, it may be that is the standard default option when requesting a restricted zone. You know -' state size of zone required: 2nm, 5nm or provide defining co-ordinates'
It doesn't sound as if the folk doing this were likely to be aware of the need to check airspace!
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Modellers all over the world will miss that wit and astonishing depth of knowledge. A wonderful turn of phrase too. I learnt a lot about engines reading his articles. Sad news.
Edited By John Bisset on 26/08/2019 13:24:32
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Erflog, Actually I agree with your comments - I do see that there is increased risk. My point was that good training of competent individuals can mitigate that. where reasonable justification exists.
I suspect that is mostly that you and I have different perceptions of 'acceptable risk', which would likely vary across the range of our various activities !
Cheers.
John
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I'm not quite sure what you mean there Erfolg.
By its nature, all driving is dangerous, it simply remains to determine what is acceptable.
(If we were starting from scratch in today's relatively risk averse society, manually operating large fast moving lumps of metal, containing highly flammable fluids, in close proximity to pedestrians, as happens in any city street, would never be allowed!)
Most drivers are minimally trained - all our 'test' requires and at best minimally competent. The variation in capability seen daily on our roads is astonishing. A well trained driver, with good reactions and understanding of the task & its limitations, focused alert and operating a well maintained vehicle is, I'd suggest, less of risk than many a wandering half awake stumbly who doesn't know (or care) how wide his car is, who indicates after starting to turn, who runs too close up behind and who can't even reverse park the brute!
What does 'posted maximum speed' have to do with it? That is an arbitrary value, often set without regard to the realities of the road - and it may be a dangerously high speed itself in some conditions. Just because it is legal doesn't make it sensible.
The police driver is also regularly assessed and given practice in emergency handling, which adds to his/her safety in operation. This is something I wish was applied to us all. I'd happily sit a retest every few years , as I do for flying. My capability is checked and further training and testing provided if necessary.
Martin Harris made a good point too - I'd love to see differentiation between new inexperienced drivers and experienced, trained ones, to allow variation in what is permitted. Of course the counterpoint would be that the penalties for error or trangression would be correspondingly more severe. This might help remind folk that to be allowed to drive is a PRIVILEGE not a right ! These are lethal weapons, the only ones most of us have easy access to.
And cuban8 - I wasn't aware there was a proposal to ban motorcycle intercoms. Now that is utterly absurd !
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Years ago I had a policeman tick me off for eating an apple whilst stationary, engine off, in a motorway traffic jam. Yes, I was behind the wheel, but no-one was going anywhere, given the solid queue to the horizon.
Amused me and annoyed my kids, who thought it stupid.
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Posted by J D 8 on 22/08/2019 13:23:11:
I live in an area where most of the roads are single track with passing places. It would seem to me that being able to reverse is no longer taught. I was on my tractor the other day and met a young chap in a little Renault.
It was painful watching him try to reverse ten yards in a straight line to a passing place, each attempt ended in the hedge, he just had to turn the wheel when all that was needed was to leave it alone.
I gave up in the end and went back to the next passing place. He drove by with a sheepish look on his face as I nodded my
.Likewise we have some narrow roads where the ability to reverse, or to look & think well ahead, helps. In fact we frequently have folk reversing past our front garden because of a bend and narrow stretch just beyond us. So far the hedge and fence have survived...
It does intrigue me how few people reverse park today; that is a useful bit of practice they miss. It also avoids the laborious and arguably rather unsafe multi shunt exits!
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JD8 has good point too. How could we police this?
Every day I see cars - and especially vans - passing my house, out in the country on a quiet road, with phones clamped to their ears. At least with hands free they have both hands available even if not a brain!
So the existing laws are ignored, daily, routinely. Little point adding extra law which just penalises the sensible. (Not that this will necessarily stop it happening!)
This is very much like reducing further the alcohol threshold to cut drunk driving; the vast bulk of the remaining drink driving problem is people way over any limits - so cutting the allowable level just allows MPs to pretend they are achieving something. The indignant gutter press like it too.
What we need is to find a way to shame people into NOT using a mobile phone. It worked,.mostly, with drink driving, eventually. I can't suggest how.
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I agree with Cuban, though I do understand Alex' point.
Of course it is important not to get distracted - when I had a hands free phone I used to start any conversation with a warning that I was driving. Hence there might be a pause or a comment of 'Wait' at any time,. This is exactly the same as when flying - we were taught to 'aviate, navigate, communicate' in that order.
I did the same with kids or talkative folk in the car -if things got busy I would call for silence. Generally., folk understand this quickly.
The point is of course I was TAUGHT to do this. When we taught our kids to drive I did the same - as I did with my flying pupils. (A favourite check was to wait until a pupil was on final approach to land, then ask for name and address or date of birth. What I wanted was either silence, or a mutter of 'not now'.
We don't teach new drivers this; we should. There is a hierarchy of tasks to do as a driver. But then, there are so many other things not taught. Skid training? Snow or ice driving? High speed driving so folk know what a car feels like close to the limits. Even proper overtaking is seldom taught unless you learn in a country area. Now motorway driving can be taught, at last!
(It has always surprised me that it bis technically legal in the UK to light a cigarette, with all the hazards that involves, but not eat food while driving.
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Thanks Andy. I have found some photos which I think may show your machine, with the servos on a tray which sits well forward to help the CG challenge.
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Posted by Biggles' Elder Brother - Moderator on 11/10/2018 07:58:46:
The weight question has filled me with curiousity now! It's perfectly possible my memory is at fault - it was some time ago when I put this together.
I'll try to nip out to the shed this afternoon and quickly weigh the WOTTY. I'll report back.
BEB
Your memory sounds fine to me - I checked my rebuilt, electric Wot 4 just now and got 4.4 lbs, with a 4S battery. Mine is rebuilt from a 25 year old style Wot, may not even be a Mk2.
John B
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Thanks for that link Martin. Interesting.
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I am intrigued by the comments about chopping the fuselage behind the wings to make car carriage easier. How is that done? How does the fuselage fasten together and how do the control runs connect?
(I have a long dormant Puppeteer build tucked away - one day soon I shall get back to it...)
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Well said Mr Knowles - my feelings precisely !
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Does the bunt surface inhibit the uptake of any of our commonly used glues?
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As a simpler and smaller scale option , I found a copy of a 48 1/2" span DH60 Moth plan, given away free with RCME in Dec 1985.
That doesn't have any folding wing information so is probably a simplified and reduced scale effort and hence not of much interest to you I expect. I haven't found the article to go with it, yet.
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Jon, that sounds like the model needs the same tie rods for the lower wings as the real thing !
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Looking at my plans for the Precedent Stampe, measuring the tailplane incidence (lower surface of tailplane) with reference to the upper fuselage longerons, which make a ~ good level reference, the tailplane measures at 4 degrees nose up.
(That sounds a lot. Mine is a kit from ~30 years ago, still not built. I will have to hunt around for an instrcution booklet; it's not in the box, so I must have taken it out to dream over.)
It's not so easy from the plans to determine wing incidence accurately. Looking at the plan and making my best guess of chord line, then transposing that up using (nautical !) parallel rules,the lower wing incidence appears to be around 5.5 degrees nose up. I'd suggest both my figures are +/- around 0.5 degree. Does that help?
I think both wings should have the same incidence at the root.
I have an aircraft engineer friend who is rebuilding a full size Stampe right now, and is close to re-assembling wings and tailplane. I could ask him what the values should be, though the model values may differ. I think his son has a Precedent Stampe part built.
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That's beautiful work, cymaz, and a lovely aeroplane. I'd be scared to fly it !
Edited By John Bisset on 09/08/2019 15:41:04
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Part of the challenge with these apparently 'flimsy' fixings is our human tendency to equate 'bigger' with 'stronger'. Actually of course, that often isn't so. Toughness - which is typically more important for durability - may be better with a slimmer, lighter piece of structure. The stiffness of a hollow tube compared to an equivalent weight solid rod is a classic example.
That said, when I first looked at a Hornet Moth's folding mechanism I too was taken aback at its simplicity and lightness. And yes the bolts typically used to secure engines in light aircraft do look undersized, especially if you plan to do aerobatics. Thinking about the torque loads alone makes you wince. I used to fly Pawnee glider tugs. Hefty, tough design made for rugged use. Now I fly a Eurofox, an uprated microlight aircraft which has some radio control model size fixings and some R/C adapted minor control attachments. It is in fact a very capable and strong aircraft, though I still have a hankering for the reassuring bulk of the (expensive to run) Pawnee!
And if you ever see a modern airliner with the wing root fairings removed, the actual retaining bolts are quite surprisingly slender and few in number. That big root section looks impressively solid...
An excellent materials engineer and trainer whom I knew said that the most astonishing about metals is not how strong they are but how weak. They all have much higher Young's moduli than their in service strengths might suggest. Why? - because they are full of imperfections. Still, best not tell the 'general public' that !
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A most useful set of posts Colin - and a salutary lesson for us all. Thank you for this cautionary tale and I hope you continue to recover fast.
My wife, also a pilot, normally helps me with hand launching when necessary. We both read your account with great care & some trepidation - and see common elements in what we do. We shall be changing our launch style immediately!
As you say, we should really think of these as cutting tools - mobile buzz saws. Shudder! I shall try to think of these from now on in the same way as the prop on a fullsize aeroplane, which gets a wide berth. Perhaps the old days of hand swinging small model engines had acclimatised me to thinking sloppily about them.
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I will be interested to know how well the wing slots work out - certainly did a fine job for low speed control on the Turbulent.
I wonder, is part of the problem here that the wing loading has presumably gone up? A smaller model than the original Wot 4 will have less wing area and while total weight will be down, it may well not be in proportion. This is a common re-sizing problem. Smaller motor, battery and ESC will be lighter but maybe not so much.
That would explain the 'drops out of the sky when throttle cut' performance. It might also help explain some of the squirrely behaviour, since a higher wing loading will put more emphasis on the wingtip vortices and any slight build variations at the tips could show up, be magnifiied. If some of the pilots are also pilots of larger Wot 4s, are people subconsciously expecting the benign handling of that machine too?
(I recall a fullsize two seat sailplane we put a wingtip camera on years ago, overseas. This was long before GoPros etc. The camera was small but the rudder required to hold straight in flight surprised us. So did the stall - quite a vicious wing drop we'd never experienced before. Taping a similar sized block of wood to the other tip evened things out, but after that and a couple of other surprises we stopped doing ad-hoc mods. We realised why test pilots are required- even small changes can make a big difference! )
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That is useful information about Halfords Martin, thanks. My previous source for cellulose paint was a local motor parts supplier, but they now only seem to have acrylics and two pack.
I too have some basic colours in cellulose stored away, plus some old cellulose paint mixers which I got from a garage which was giving up spraying. Those I have to keep thinning back, since the tins and jars leak slowly. Luckily cellulose paint can recover quite well.
undercamber wings
in Building from Traditional Kits and Plans
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Thanks for that PatMc.
Is that a Schleicher ASK14 in your picture/avatar? I think there are only two or maybe three of those in the UK - nice machines.