RE: 90-degrees of lock at 500mph | Bloodhound LSR
Discussion
Article said:
"we had an aborted run because there were no anti-bounce software on the switches in the cockpit"... "we simply didn't have it fitted to the car because we didn't know we were going to need it."
This really surprises me. All mechanical switches have bounce, but it's trivial to filter in software, so I don't know why you wouldn't do it as a matter of course.Edited by LexiconUK on Monday 11th November 12:53
NFC 85 Vette said:
It's quite an odd sensation, and goes against everything you ordinarily do when steering a car at speed. My old Fiat racecar had a trait of picking up the front wheels North of 180mph. When it then started to lurch toward either the centre line or concrete wall, the temptation was of course to steer in the opposite direction. With that not being effective, I found a better way was to turn the wheel towards the direction of travel - if it was still carrying the front end, most of the time it helped bring it back, but of course when the front wheels do touch down, there's only a brief moment to correct it before you're toast. Quite how they work as rudders as I was never really sure, they didn't have Mooneyes wheel discs or any aero covers attached to them.
With Bloodhound, it's easy to forget just how big and how heavy it is; there's a lot of mass that creates great big yaw numbers when it starts to get jiggy. Along with Thrust SSC, the onboard video is a good demonstration of why driving fast in a straight line isn't as simple as some would have us believe
NFC 85 Vette: This Fiat racecar sounds like it deserves its own thread.With Bloodhound, it's easy to forget just how big and how heavy it is; there's a lot of mass that creates great big yaw numbers when it starts to get jiggy. Along with Thrust SSC, the onboard video is a good demonstration of why driving fast in a straight line isn't as simple as some would have us believe
blearyeyedboy said:
NFC 85 Vette: This Fiat racecar sounds like it deserves its own thread.
It wasn't exciting enough for its own thread. Did go over 200mph on the back wheels though 
The data showed going through the 1/8th mile timing reflectors at 183mph (the orange lumps on the track to the left of the car). It's not a great photo, but you can just about make out the wheels pointing toward the wall. It had picked the left front up at about 300ft out and never put it down again. Hacksawing at the wheel eventually got the front settled and then it made a move for the centre line just before 1000ft (kicked out 2 rods and oil got under the rear tyres). As much fun as it was to drive, it was a bit of an unruly animal.
LexiconUK said:
Article said:
"we had an aborted run because there were no anti-bounce software on the switches in the cockpit"... "we simply didn't have it fitted to the car because we didn't know we were going to need it."
This really surprises me. All mechanical switches have bounce, but it's trivial to filter in software, so I don't know why you wouldn't do it as a matter of course.Edited by LexiconUK on Monday 11th November 12:53
50ms is the value I use as a default pending any actual measurements.
NFC 85 Vette said:
It wasn't exciting enough for its own thread. Did go over 200mph on the back wheels though
The data showed going through the 1/8th mile timing reflectors at 183mph (the orange lumps on the track to the left of the car). It's not a great photo, but you can just about make out the wheels pointing toward the wall. It had picked the left front up at about 300ft out and never put it down again. Hacksawing at the wheel eventually got the front settled and then it made a move for the centre line just before 1000ft (kicked out 2 rods and oil got under the rear tyres). As much fun as it was to drive, it was a bit of an unruly animal.
The data showed going through the 1/8th mile timing reflectors at 183mph (the orange lumps on the track to the left of the car). It's not a great photo, but you can just about make out the wheels pointing toward the wall. It had picked the left front up at about 300ft out and never put it down again. Hacksawing at the wheel eventually got the front settled and then it made a move for the centre line just before 1000ft (kicked out 2 rods and oil got under the rear tyres). As much fun as it was to drive, it was a bit of an unruly animal.
Thanks for sharing. Fiat Punto it isn't!
(I'm sure a Punto was the origin of the "Cadence Clutching" thread...)
14 said:
I thought they did because it was set to 10m/s. They’ve now set it too 300m/s
verbatim said:
there were no anti-bounce software on the switches in the cockpit, we had a switch bounce of less than ten milliseconds and the jet engine shut down. We've now got some anti-bounce software
I read that to mean no anti bounce at all.Switches actually have <10ms bounce.
Now got anti bounce.
No value specified, where did you get 300ms from?
I'd say 300ms is a bit long for a real time single press. It's easily possible to press a switch for less than this and the press is ignored.
The only occasion I've used a time this long is when counting of multiple presses are needed, not for anti bounce.
It was for a semi-auto truck gearbox where multiple shifts could be requested at once. Was a 12speed box!
Not uncommon to want to jump ratios.
ok makes sense, you'd not want any shockwave going downward so therefore it has to be low
BrettMRC said:
It's to do with moving the shockwave IIRC.
Yes, air does some really weird things in the trans-sonic region, IIRC the nose design is for a neutral downforce effect as the vehicle moves from subsonic to supersonic. Except that no land vehicle has ever gone supersonic for more than half a dozen seconds, and the one that did that was driven by the same pilot 22 years ago.
This really is rocket science, and all we can do is with them luck!
Edited by Sandpit Steve on Wednesday 13th November 05:46
"During the final run the analysis showed that airflow beneath the car had gone supersonic and stripped paint from an area three meters back from the front wheels....."
Not anything to do with the sand....?
Just reads as the area behind the wheels was traveling faster than the rest of the car...which is obviously nonsensical
And how much downforce is that faster airflow beneath generating ?
Not anything to do with the sand....?
Just reads as the area behind the wheels was traveling faster than the rest of the car...which is obviously nonsensical
And how much downforce is that faster airflow beneath generating ?
blue al said:
"During the final run the analysis showed that airflow beneath the car had gone supersonic and stripped paint from an area three meters back from the front wheels....."
Not anything to do with the sand....?
Just reads as the area behind the wheels was traveling faster than the rest of the car...which is obviously nonsensical
And how much downforce is that faster airflow beneath generating ?
The airflow had gone faster in that area, why is that nonsensical?Not anything to do with the sand....?
Just reads as the area behind the wheels was traveling faster than the rest of the car...which is obviously nonsensical
And how much downforce is that faster airflow beneath generating ?
blue al said:
"During the final run the analysis showed that airflow beneath the car had gone supersonic and stripped paint from an area three meters back from the front wheels....."
Not anything to do with the sand....?
Just reads as the area behind the wheels was traveling faster than the rest of the car...which is obviously nonsensical
And how much downforce is that faster airflow beneath generating ?
Venturi principle; fluids move faster when moving through a narrower area, balanced by a drop in pressure. It makes sense that air would be moving faster in certain areas around the car.Not anything to do with the sand....?
Just reads as the area behind the wheels was traveling faster than the rest of the car...which is obviously nonsensical
And how much downforce is that faster airflow beneath generating ?
Don't forget, they're aiming for neutral downforce, it always exists they have to balance it out. So if the air above the car is generating 5000kg of downforce then they need to create 5000kg of lift to balance it out. The car is litterally being squashed by huge amounts of pressure at these speeds to give it an equal amount of lift and drag.
Really is a fantasic bit of engineering and a great achievement if they can get even close to 1000mph.
Snubs said:
I love the fact that on a test run it was doing pretty much the same speed that Thrust2 peaked at (1,010km/h vs. 1,020km/h).
Still, as a child of the 1980s Thrust2 will always be special to me
Likewise! There is something truly nostalgic about the golden thrust 2 for me. That along with the awesome SR71 Blackbird (I know it's the 60s) are truly iconic designs. Still, as a child of the 1980s Thrust2 will always be special to me
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