Bloodhound Supersonic Car

Flatlander · 2015-03-16, 16:38

Is the maths here wrong or am I going mad (it could be both of course):

Bloodhound: Superwheels for supersonic car go into production

kladner · 2015-03-16, 16:41

Quote:

Originally Posted by Flatlander

Is the maths here wrong or am I going mad (it could be both of course):

Bloodhound: Superwheels for supersonic car go into production

Corrected link:
http://www.bbc.co.uk/news/science-environment-31845234

ewmayer · 2015-03-16, 23:39

Fascinating stuff about the high-tech disc wheels - thx for the link(s).

VBCurtis · 2015-03-17, 07:42

Which maths are you doubting?

radial (centripetal) acceleration = r * (angular velocity)^2.

170 rev/sec * 2pi = 1068 radians/sec. r = 45cm, so a = 510000, or 50000g after some rounding to be conservative.

10500 RPM was also claimed; divide by 60 to get the same 170 rev/sec (again, rounded for journalistic use).

A number not cited in the article: 1068 rad/sec *r = 480 m/sec linear velocity of car. But a m/sec is 2.23 MPH, so 1070 MPH. That's only a little higher than the target speed record, which is averaged over a mile or more.

Flatlander · 2015-03-17, 18:12

I was out by a factor of ten for some reason.

2015-03-16, 16:38	#1
Flatlander I quite division it "Chris" Feb 2005 England 31×67 Posts	Bloodhound Supersonic Car Is the maths here wrong or am I going mad (it could be both of course): Bloodhound: Superwheels for supersonic car go into production Last fiddled with by Batalov on 2015-03-16 at 16:42 Reason: (link)

2015-03-16, 23:39	#3
ewmayer ∂²ω=0 Sep 2002 República de California 3×53×73 Posts	Fascinating stuff about the high-tech disc wheels - thx for the link(s).

2015-03-17, 07:42	#4
VBCurtis "Curtis" Feb 2005 Riverside, CA 5²×11×17 Posts	Which maths are you doubting? radial (centripetal) acceleration = r * (angular velocity)^2. 170 rev/sec * 2pi = 1068 radians/sec. r = 45cm, so a = 510000, or 50000g after some rounding to be conservative. 10500 RPM was also claimed; divide by 60 to get the same 170 rev/sec (again, rounded for journalistic use). A number not cited in the article: 1068 rad/sec *r = 480 m/sec linear velocity of car. But a m/sec is 2.23 MPH, so 1070 MPH. That's only a little higher than the target speed record, which is averaged over a mile or more.

2015-03-17, 18:12	#5
Flatlander I quite division it "Chris" Feb 2005 England 31×67 Posts	I was out by a factor of ten for some reason.