Bloodhound testing

[MAYOMAN]

Apparently I misunderstood what Andy Green told me. He was probably relating that the yaw stability provided by the vertical stabilizer overcame the steering instability as the speed rapidly increased. Nonetheless the Thrust SSC achieved the memorable first - exceeding Mach 1 on land for the first time in an automobile. I attached (I hope) some photos of the Thrust SSC stabilizer.

[TD]

Interesting, I wasn't aware of that component.   

Below is a photo I took in September 1997.  The bit of bodywork directly beneath (visually) the spray can appears to end in a somewhat different spot than it does in the museum photo.  Also, the ride height appears different, in that the wheel hub is visible, in front of the crew member's left leg.

Edit:  After a quick check of the cutaway drawing in Noble's book Thrust it looks like this difference may be due to suspension droop, there appear to be struts in the rear.

Great stuff, thanks!

[MAYOMAN]

I thought I had sent all three photos. I think I got it this time.

[gowing]

I may be waaaay off track on this,
but...... if the issue is drivability at speed (over 650 mph.) , I ask myself: what is the difference between the cars that have done it and those that haven't.

When I compare the design of Bloodhound VS. Thrust, the thing that is most apparent to me is the track width of the front tires. Width = Stability.

Thrust has proven that the "reverse trike" platform has merit, and that being wide doesn't mean going slow.

From seeing the control issues of the Bloodhound, the Carbiliner and the NAE, they all have one thing in common, the small FA "tricycle" design of the vehicles.

I'm no engineering genius, just a backyard mechanic, but in my world (dirt), width is good.  Give me a wide stance anytime.

[MX304]

Interesting, I wasn't aware of that component.   

Below is a photo I took in September 1997.  The bit of bodywork directly beneath (visually) the spray can appears to end in a somewhat different spot than it does in the museum photo.  Also, the ride height appears different, in that the wheel hub is visible, in front of the crew member's left leg.

Edit:  After a quick check of the cutaway drawing in Noble's book Thrust it looks like this difference may be due to suspension droop, there appear to be struts in the rear.

Great stuff, thanks!

It had struts but it also had active rear suspension. They could raise and lower the rear ride height to control the down force. That system gave them trouble late in the program when it suffered a structural failure on a fast run.

[TrickyDicky]

Interesting, I wasn't aware of that component.   

Below is a photo I took in September 1997.  The bit of bodywork directly beneath (visually) the spray can appears to end in a somewhat different spot than it does in the museum photo.  Also, the ride height appears different, in that the wheel hub is visible, in front of the crew member's left leg.

Edit:  After a quick check of the cutaway drawing in Noble's book Thrust it looks like this difference may be due to suspension droop, there appear to be struts in the rear.

Great stuff, thanks!

It had struts but it also had active rear suspension. They could raise and lower the rear ride height to control the down force. That system gave them trouble late in the program when it suffered a structural failure on a fast run.

I'm not an expert either, but isn't "active rear suspension" a bit misleading?  From memory, I thought the ride height at the rear could be adjusted when stationary (e.g. in the pits), but not dynamically during a run.

Or I could be getting it confused with Thrust2 ...

[MX304]

Interesting, I wasn't aware of that component.   

Below is a photo I took in September 1997.  The bit of bodywork directly beneath (visually) the spray can appears to end in a somewhat different spot than it does in the museum photo.  Also, the ride height appears different, in that the wheel hub is visible, in front of the crew member's left leg.

Edit:  After a quick check of the cutaway drawing in Noble's book Thrust it looks like this difference may be due to suspension droop, there appear to be struts in the rear.

Great stuff, thanks!

It had struts but it also had active rear suspension. They could raise and lower the rear ride height to control the down force. That system gave them trouble late in the program when it suffered a structural failure on a fast run.

I'm not an expert either, but isn't "active rear suspension" a bit misleading?  From memory, I thought the ride height at the rear could be adjusted when stationary (e.g. in the pits), but not dynamically during a run.

Or I could be getting it confused with Thrust2 ...

SSC was active. Thrust2 was adjustable between runs. When they had the structural failure on SSC, they tried the next run with it locked out. That was almost catastrophic as the extra down force in the transonic speed range buried the front wheels in the desert and the car got divergent. They then switched back to active but with a limited range of movement.

[wobblywalrus]

It is entirely possible to have an aerodynamically stable vehicle that is not going in the intended direction with no means to realign it.  Both stability and steering control are essential.

[martine]

...I'm no engineering genius, just a backyard mechanic, but in my world (dirt), width is good.  Give me a wide stance anytime.

I understand your thinking but my understanding is a wide vehicle would generate much too much aerodynamic drag...you'd never get to 800 mph.

...And I thought Bloodhound seemed remarkably stable above 500 mph - or perhaps I'm missing something.

[wobblywalrus]

That is what I am worried about and why I crawled out of my hollow log to say something.  Stability is part of the high speed handling equation.  That seems to be figured out.  Steering at speed is the other part.  Has anything been done about this?

It appears that wheel based steering might not work.  It would be crazy to depend on it alone.  A non-wheel based steering method is needed as a primary means of directional control or as a backup steering system.

[tallguy]

Functionally, steering that is not wheel-based makes sense to me.  But I'm not sure it's legal per all the
organizations that sanction the runs.  Maybe it should be made broadly legal?

[martine]

Functionally, steering that is not wheel-based makes sense to me.  But I'm not sure it's legal per all the
organizations that sanction the runs.  Maybe it should be made broadly legal?

Certainly the FIA don't have any restrictions on steering for unlimited world land speed record cars...don't know about anyone else but Bloodhound is going for the FIA record so it's not a problem.  As long as it's got 4 (or more) wheels and steering, throttle and brakes are controlled by the driver - there are no technical restrictions to worry about...anything goes!

[MAYOMAN]

In 1962 Craig Breedlove's Spirit of America had a fixed (non-steering) front wheel and a steering fin in front of it. Also, no vertical stabilizer. The result at Bonneville was he could not steer the car. The following year, after considerable redesign, the articulating front wheel was the steering method and the vertical stabilizer appeared. Result? A new absolute world land speed record, first over 400 mi/h, certified by FIM.

[wobblywalrus]

Some news about the bloodhound.https://www.bbc.com/news/science-environment-51495610

[MAYOMAN]

After all that blather about the HTP rocket, no mention of the required thrust. I might just have one in my garage.