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Originally Posted by Wowbagger I was at the Nats on the Saturday and watched this aircraft fly. Now my views may upset a few people but nevertheless I believe them to be true.
In my opinion this aircraft should never have been flown in the prevailing conditions. I watched it lurch around the circuit with big pitch changes and serious wing flex/twist evident. I felt it was so bad that I went back to the trade stands in case of an incident. It flew again later on and displayed the same handling characteristics. A couple of days later I was downloading the video of the, not unexpected, crash.
My worry is that if one of these things gets into a crowd of spectators, we can expect serious limitations in the operation of our models. It'll focus establishment interest in us. To fly machines such as this at public displays is courting certain disaster. The Nats may not be too bad as there is good crowd/flight line seperation, but we can all think of plenty of shows where this seperation is very close indeed. The results of the B52 in a crowd just doesn't bear thinking about. You have people buying radio gear close to the flying and obviously switching it on at their cars, which in this case were even closer to the flight line. It's no good saying they shouldn't do it, they do do it!
In my opinion these projects are not properly researched and I'm suprised that full size flying notes were not taken into account by the people building and flying it, and (I assume) the LMA inspectors who must have inspected it at various stages of its construction.
It is all very worrying. A couple of years ago a big Lanc' tucked in at a show during a high speed pass. In Henshaws book, "Sigh for a Merlin", he states that a Lanc' will enter an uncontrollable "tuck" at speeds above 320 IAS (if memory serves!). If the builder/flyer had have thoroughly researched this aircraft the crash could have been avoided. It's highly likely for these large machines to exhibit the same flight characteristics of their big brethren.
I've watched LMA pilots at shows hauling very large models into the sky time and again. The pilot obviously having no real understanding of what he's doing. I watched another Lanc' abused in this way at Weston Park last (I think) year with the inevitable stall and, fortunately, left wing drop into a tree. If it had been right wing drop he'd have been in the crowd. This year it was a jet jockey showing off his (very poor) knife flight skills, the model threatening to pull into the crowd time and again, the pilot obviously flying beyond his capability. He too found a tree and totally destroyed the model. At full size shows any deviation from prescribed shedule means an instant landing. It should be the case at large model events too. A 250 mph jet may be exciting stuff but a glitch putting the model out of control at these speeds frightens the life out of me. Imagine a 15 pound model hitting someone at 250 mph. A half second loss of control could easily put such a model into the crowd line.
250 pound models built of skinned blue foam just doesn't get the job done. This size of aircraft should come under CAA inpection in my opinion. I also think commercially available mass produced radio gear (TX and RX) is asking for trouble too. These items should be subjected to some form of reliability testing before use. Even a special frequency should be considered. Batteries and so on should certainly be CAA passed.
I'm afraid terms such as "terrific achievement" and "super model" leave me completely unimpressed. This thing was an accident just waiting to happen. By the grace of God it didn't fly off into the crowd and kill/burn a couple of families with kids. Let's get on it before it does happen. |
***There are some valid comments in what you say and I would like to add a few of my own gleaned from large model pilots/builders etc and the general concensus of opinion,firstly when a model is scaled down to such huge proportions as the B-52 the same flight envelope as the real machine should be observed,for example in the case of the B-52 it is well documented and known that any increase in bank dramatically affects this swept wing bomber,the number lost in Vietnam alone showed that due to evasive action the bomber would slide sideways out of the sky out of control,the models built of the B-52 in reent years have displayed this characteristic unfavourable behaviour,it has to be said that any model is only as good as its pilot and just how do you get training on such monsters ? very specialised stuff indeed,it looks likely that the CAA will take note of what happened and probably stipulate that pilots will need training-as full size pilots,sounds like a bit of an overkill but this has been on the books now for some time,in a lot of ways it will kill the large model business but awareness is better than one big accident just waiting to happen.
One thing that does concern me is the apparent lack of regard for some aspects of stability and the way the model handles,from observations of video footage it was obvious that this model looked very sensitive in the fore and aft trim constantly requiring pitch trim changes,perhaps the centre of gravity/thrust lines etc were not quite right,lets face it getting a small model trimmed is bad enough but to balance out such a monster as this needs lots of extra special care,it only takes a few degrees out of trim to cause problems.
Whilst I know that there are dedicated inspectors operating throughout the country to periodically keep an eye on such projects the inflight stresses on even a very basic ultralight aeroplane require a very experienced stress engineer to carry out the calculations,when you are dealing with large chunks of foam with stressed skin covering the displacement of metal fittings needs to be carefully worked out,the stressmans job is to work out the loads under what he expects the aircrafts ability to handle in terms of g-forces,every little rib and fitting needs to be calculated in terms of what can it do ? in the case of foam/veneer blocks which is how a lot of these large models are made a relatively unknown factor has to be worked on,this became apparent when the glass skinned foamies such as the Quickie,Rutan designs came about,as it happened a new problem came about-leading edge wing behaviour in rainy conditions,the first one third of the leading edge of the wing developed strange behavious.
So what I am saying is the inspection is only as good as the known elements of aircraft design and construction,it has to be based on sometimes tenuous formulae.
Whilst not wishing to stop the production of these large models,I do feel that not enough design consideration and stress calculation is taken into consideration and the inspection side needs to be looked at more closely otherwise accidents like the one that happened to this model can and will happen more frequently.
Anyone who has seen a PFA inspector at work will know what I mean,no stone is left unturned in the interests of safety,if it will loosen or break then everything needs to be considered.
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