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Re: Pic of the Day
Posted: Sat May 02, 2009 6:09 pm
by rob565uk
That is certainly a great picture Mike - but don't beat Bill too hard when he is only just getting over gout !
Re: Pic of the Day
Posted: Sat May 02, 2009 7:04 pm
by Renegadenemo
nope - it flippin hurts. But a good day on the tin as Mike says.
Re: Pic of the Day
Posted: Tue May 05, 2009 8:04 am
by ace_chris
KW Mitchell wrote:klingon wrote:Keith with reference to the front engine tie bar failure -would this have contributed to the lifting of K7's nose by acting basically as a vectored thrust engine due to torque reaction and movement of the tailpipe?-
When the Orpheus was fitted, we know that Leo Villa and Ken Norris made the adjustments to the alignment. Jet engines produce thrust directly down the central axis so, theoretically, the engine should have been aligned to BB's central axis. The tie-bar is threaded with an adjustable turnbuckle and we know that LV made the adjustments while KN indicated a 'small amount' of down-thrust
(how much is not recorded) so that the nose-down couple was increased.
If that tie-bar failed due to the buffeting and consequent pitching in the final run, the engine could rock on the main mounting gimbals. It would not need to be much to contribute alternately up- and down-thrust,
the effects of which can only be imagined ---------------!
Keith
When/If the tie bar failed allowing the engine to rock on its mounting gimbals, would this be evident from the film footage leading up to the crash? Would any failure cause the engine to move INSTANTLY, or would it take a few seconds for it to happen. Must admit havent seen the accident footage for a while (about a week, must be losing my touch!) but I guess any kind of movement would be evident on the film? Chris
Re: Pic of the Day
Posted: Tue May 05, 2009 9:28 am
by Renegadenemo
All you would see is what we did see - with the front of the engine no longer attached to the frame it would be unable to damp the pitching movement due to the gyroscopic effect of the spinning engine and the thrust line would alter to the point where the nose-down moment was lost next time the nose was bounced upwards. There'd then be nothing to bring it back down again and the centre of pressure on the underside would move aft making the problem worse.
Re: Pic of the Day
Posted: Tue May 05, 2009 11:41 am
by KW Mitchell
I think the following section of video is illuminating:
http://www.youtube.com/watch?v=n3ftZfB-VNQ
(derived from
'Across the Lake').
As BB passes the face of the camera tramping very severely (timer marker: 6.00mins >) there are then 3-4 pitching cycles when the boat is completely clear of the water then banging down (timer marker: 6.08mins >6.10mins).
Tramping is not occurring during this phase as the fin is visibly straight up and down and not rolling side-to-side.
BB is fully airborne in those phases. The question is;
'Is this the result of marginal stability alone and down-thrust couple is restoring BB to the water surface after each pitch into the air or is it more complicated and compounded by an oscillating thrust (fuel starvation/controlled throttle reduction cause or oscillating thrustline component due to a moving engine ---------------'.
Re: Pic of the Day
Posted: Tue May 05, 2009 12:11 pm
by Renegadenemo
Wonderful piece of music and hands up all those who can't wait to see that amazing machine back on the water...
Re: Pic of the Day
Posted: Tue May 05, 2009 5:27 pm
by Drewski
I've definetely got my 2 hands up Bill........ lets hope for calm waters, blue skies and let the miracle begin !!!
Re: Pic of the Day
Posted: Tue May 05, 2009 7:12 pm
by jonwrightk7
both hands up here too!!!!
Re: Pic of the Day
Posted: Wed May 06, 2009 8:21 am
by ace_chris
Bill, thanks for your reply re my earlier question regarding Bluebird's thrust line and I guess the factors leading up to Bluebirds accident on January 4th will be debated for many a year to come. With all the advances in technology following the accident, I wonder if Bluebird's last 'run' could be somehow recreated using a Computer. Factors such as the damaged spar, the damaged engine mount, water conditions, engine instability could be re-created. There must be a university out there who could do this sort of thing, be good incentive for their students to get up before lunch time and give up Jeremy Kyle! Chris
Re: Pic of the Day
Posted: Wed May 06, 2009 7:04 pm
by KW Mitchell
Bill - re' the pic' of the gauge(s) recess, did they survive?
If they did, did the boost pressure and hydraulic pressure ones indicate a reading? Probably wouldn't mean anything anyway, but you know where I'm going on this one - the reading 'frozen in time' thing. Often very important in aviation crash analyses before black-boxes -----.
Keith