Bloodhound LSR Thread As Requested...

Bloodhound LSR Thread As Requested...

Author
Discussion

warmfuzzies

3,975 posts

253 months

Monday 28th July 2014
quotequote all
IN51GHT said:
In the region of 800mph, they will be deployed to maintain a constant 3g deceleration by using a close loop control system with the line pressure as the input.
Forgive my ignorance, but why 3g? Does that equate to a speed reference over distance??

Cheers.

K.


Squiggs

1,520 posts

155 months

Monday 28th July 2014
quotequote all
IN51GHT said:
Roland (head of stress)
What a rotten job that must be!

Does he have to soak up all his workmates anxieties and problems?
And then once he has does everyone else carry on working on the project without a care in the world in a tranquil environment whilst the poor chap, near to breaking point, locks himself in a small room ready to start punching and head-butting the walls?
getmecoat

Silent1

19,761 posts

235 months

Tuesday 29th July 2014
quotequote all
Max_Torque said:
Silent1 said:
Max_Torque said:
IN51GHT said:
In the region of 800mph, they will be deployed to maintain a constant 3g deceleration by using a close loop control system with the line pressure as the input.
"line pressure"? As in brake line pressure?
Perhaps they're measuring the hydraulic line pressure and using that to adjust the angle and aim for 50kn of force on the air brakes?
Except the actuating linkage ratio looks to be highly dependent upon actuator position, and so hydraulic pressure will not be linear with drag/deceleration!
indeed it does, i think the photo shows the linkages in the deployed position meaning that as the rams get closer to home the range of movement will be greater, which makes me think that perhaps as the car slows down the movement at 800mph with x-psi would be x-inches and at 400mph for the same psi the movement would be 4x-inches both of which provide the same deceleration.
Or they've worked out the required pressures and have set pressures for certain speeds, but it would be cool if the deployment ratio matched the deceleration meaning you just have to hold x-psi in the line and it slowly opens as the car slows.

mcdjl

5,446 posts

195 months

Tuesday 29th July 2014
quotequote all
As the aerodynamic drag is a function of the square of the speed then they'll need to open faster as the case sites down to have the same effect, however as they open more the frontal area will be getting bigger generating more force. That might explain why the ratio is non linear, but I might also have made it up.

IN51GHT

Original Poster:

8,777 posts

210 months

Tuesday 29th July 2014
quotequote all
We know the hydraulic line pressure, car speed & angle of the doors, from which we are calculating angle at any given speed as part of the closed loop control.

IN51GHT

Original Poster:

8,777 posts

210 months

Tuesday 29th July 2014
quotequote all
The thing with having to push on with build before all of the analysis has been completed is that occasionally something bites us.

Here Roland picked up a potential stress hotspot where we are trying dump the skin load into the side rail, so just to make sure we had to beef the area up.

It necessitated a doubler on the outside, an additional Ti angle on the inside & a strap over the joggle in the angle.

The increase in drag will be immeasurable.







The layers of masking tape between the contact faces replicate the thickness of the film adhesive that is being used on final assy.

CB2152

1,555 posts

133 months

Tuesday 29th July 2014
quotequote all
Whilst trying to find out whether my ex ATC squadron managed to get their name on, I found the site where you can view every name that's going on the fin.

Fourth line down on the very right hand side, the Pistonheads Fin Allegation from a few pages back hehe



Thanks Insight thumbup

IN51GHT

Original Poster:

8,777 posts

210 months

Tuesday 29th July 2014
quotequote all
CB2152 said:
Whilst trying to find out whether my ex ATC squadron managed to get their name on, I found the site where you can view every name that's going on the fin.

Fourth line down on the very right hand side, the Pistonheads Fin Allegation from a few pages back hehe



Thanks Insight thumbup
A pleasure

HereBeMonsters

14,180 posts

182 months

Tuesday 29th July 2014
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Don't see my name there. It better be on the finished car!

CB2152

1,555 posts

133 months

Tuesday 29th July 2014
quotequote all
That's only the "block" which has the PH phrase in it. There's loads on the site so I'm sure yours is in there wink

HereBeMonsters

14,180 posts

182 months

Tuesday 29th July 2014
quotequote all
CB2152 said:
That's only the "block" which has the PH phrase in it. There's loads on the site so I'm sure yours is in there wink
Sweet, I'm on Block 15 now!

anonymous-user

54 months

Tuesday 29th July 2014
quotequote all
IN51GHT said:
We know the hydraulic line pressure, car speed & angle of the doors, from which we are calculating angle at any given speed as part of the closed loop control.
If you're "closed loop" on vehicle deceleration, then everything else just falls out in the wash (or more accurately in the "gains" you choose for you controller.......)
Of course, the clever bit is low pass filtering your acceleration signal so that your controller isn't perturbed by accelerations (or noise) it can't respond too (i'm guessing it's going to take something like 1 to 2sec to open those doors from closed, meaning your control bandwidth is going to be something less than 1Hz, ie pretty slow, and hence not exactly processor intensive. Of course, you'd also want some door angle limits and probably a suitably calibrated "feed forward" table of angle Vs velocity for any given deceleration target etc to avoid saturation and overshoot in the control response.

JordanTurbo

937 posts

141 months

Wednesday 30th July 2014
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Great to come to have a look round yesterday and meet you Mark.

Even if I didn't get to go behind the red screen rolleyeslaugh

OberonB

3 posts

116 months

Saturday 9th August 2014
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Sorry to get a bit off-topic here, but can anyone tell me why Thrust SSC employed that offset-tandem rear-wheel configuration? I have always wanted to get to the bottom of it but have never seen an explanation. It seems completely unnecessary and try as I might I cannot think of a more clumsy arrangement. It was a feature just waiting to become a problem, and very nearly did! A simple set-up like Bloodhound's side-by-side front wheels would seem to offer a far more obvious design solution.

Thanks Insight for this wonderful forum.

Colin

dave1409

218 posts

178 months

Saturday 9th August 2014
quotequote all
Has anyone sen this yet?
http://www.gizmodo.com.au/2014/08/this-jet-engine-...
(Hybrid rocket test)

Polarbert

17,923 posts

231 months

Saturday 9th August 2014
quotequote all
This looks absolutely cracking. Really enjoying seeing the updates.

CraigyMc

16,387 posts

236 months

Saturday 9th August 2014
quotequote all
dave1409 said:
Has anyone sen this yet?
http://www.gizmodo.com.au/2014/08/this-jet-engine-...
(Hybrid rocket test)
I think that might be inaccurate because it's a rehash of old information.
The Cosworth engine for the oxidiser pump is defunct, for example.

I'm not sure the Nammo rocket has actually been tested yet - or how many have been run together (unlike the original plan, the Nammo rocket will probably be a cluster).

IN51GHT

Original Poster:

8,777 posts

210 months

Friday 22nd August 2014
quotequote all
Been away for a couple of weeks much needed holiday, hence no updates, but I'm back now.

Trial fit for the AMAD (Airframe Mounted Accessory Drive) yesterday into the car.






anonymous-user

54 months

Friday 22nd August 2014
quotequote all
Is the AMAD driven from the PTO of the EJ200 or from the auxiliary (or what ever you call the ICE) engine?

Blib

43,986 posts

197 months

Friday 22nd August 2014
quotequote all
CB2152 said:
Whilst trying to find out whether my ex ATC squadron managed to get their name on, I found the site where you can view every name that's going on the fin.

Fourth line down on the very right hand side, the Pistonheads Fin Allegation from a few pages back hehe



Thanks Insight thumbup