Death of a lancaster
(An extract form the CMFC news letter)
Sadly I must report, to those who don’t already know, that Terry’s Lancaster crashed and was written off at the Hastings show in June.
The gory details are still etched in my mind, so I’ll let you in on what I think happened.
The first flight went off without a hitch and nothing seemed out of the normal. The second flight started as usual and a steady climb out ensued followed by a right climbing turn, to commence the first circuit whilst gaining height. Downwind was fine and I commenced the right turn onto base leg as normal. As she went straight and level across base leg the nose suddenly seemed to tuck down slightly. I responded with up elevator and she hesitated before coming back up. I thought ‘ that wind’s getting stronger!’ and thought no more of it. Almost immediately, the nose tucked down again, but more abruptly this time, and I suddenly thought’ I’ve got a radio problem’. Positioned ideally for an immediate landing I called ‘ I’ve got a radio problem, I’m landing’. No sooner had I uttered the words, when the nose tucked violently down again and no amount of up elevator made any difference. The dive seemed to steepen and she started to twist to the right. There was no control response of any kind and she struck the ground almost vertically a couple of hundred yards from the flight line at the end of the landing strip.
After recovering the bits (5 large plastic bags!!) we started to theorise on what happened. I kept on thinking to myself ‘why didn’t the failsafe cut in?’, but after some time, I came to the conclusion that it had. I am certain that she suffered some kind of interference which each time gave a down glitch. The PCM then ‘froze’ in the last known position for a second and then unlocked when the signal was better. This accounts for the delayed response to the first two glitches. On the third occasion, the PCM had decided that the interference was too much and went into failsafe. The nose was quite a long way down when this happened. The failsafe was set in the normal way (see my last article) and when the engines shut down the nose has a tendency to go down anyway, in this case, from an initial down to almost vertical. The small amount of up elevator programmed was nowhere near enough to compensate. The final twist was the programmed right rudder and to me was the final give-away as to what happened.
Why the glitches occurred is still a mystery, but I suspect that somebody turned on somewhere on the site and the final lock-out occurred when he put the aerial up or as the Lanc got nearer to the flight line and the signal was stronger. Having realized his error, the culprit promptly turned off and kept his mouth shut!! TX control could not validate this as I was of course transmitting on 70 and the monitor can’t tell if there’s one or two transmitters on that frequency. This is purely a theory on my part, as a study of the wreckage could find no other cause. The radio still worked fine, the battery was still fully charged (both TX and RX) and there was no obvious structural failure. A structural failure would not have accounted for all the controls locking out at once anyway, but we wanted to be sure by examining everything.
I’ve had that sick feeling before when the first Lanc went in and it doesn’t get any better the second time! I consoled myself with the knowledge that there was nothing I could have done anyway, as you need control to actually do something positively rather than spectate.
I’m glad to say that Terry and I are still keen to keep a Lanc in the air and work has started on a new one. This one will be quite a bit different to the last two and will incorporate all the lessons we have learned, not least to make it ‘dismantlable’ into smaller pieces. It will also be more scale and have both retracts as well as bomb doors. Chris Fosberry is also going to build one so we’ll have a squadron of them! Three in the air at once will be quite a sight and sound.