That’s similar to my estimate but I gave them credit for a higher pressure with
about 500 lbs of usable air. 400 lbs thrust is a help but only gets you about
0.1g with a 4000 lb car. One of Elon Musk’s tweets claimed they could get 3 g
with these thrusters which seemed pretty sporty/unrealistic to me (12000 lb
thrust). Any idea of how high a thrust a cold-gas thruster could achieve given
the 5000-10000 psi tank pressure?
From: arocket-bounce@xxxxxxxxxxxxx <arocket-bounce@xxxxxxxxxxxxx> On Behalf Of
Henry Vanderbilt
Sent: Friday, September 20, 2019 12:45 PM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Tesla Thruster Specs?
Gonna be LOUD, though.
On 9/20/2019 9:15 AM, Henry Vanderbilt wrote:
A bit of bar-napkin rocketry... N2 cold gas thruster theoretical vac Isp is 80
seconds. Guesstimate 70 seconds with real-world losses and 1 atm back pressure
(almost negligibly low compared to the thousands of psi chamber pressure.)
Air at sea level masses ~.08 lb per cubic foot. Figure you might fit a ~12
cubic foot air tank into the back seat of a Tesla, ~2 ft diameter x ~4 feet
long. At ~300 atmospheres or ~4500 psi, that's ~300 lbs of air. Figure with a
little engineering you can use 2/3rds of that before thrust starts tailing off
too much.
At Isp 70, 200 lbs of air translates to 14,000 lb/seconds of thrust. Or ~400
lbf thrust for 35 seconds. Enough to do some fancy thrust-assisted
maneuvering, yeah.
Henry
On 9/20/2019 6:48 AM, Galejs, Robert - 1007 - MITLL wrote:
Any idea of what sort of thruster specs would be practical with such a setup?
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
<mailto:arocket-bounce@xxxxxxxxxxxxx> <arocket-bounce@xxxxxxxxxxxxx> On Behalf
Of Darren Longhorn
Sent: Friday, September 20, 2019 9:39 AM
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: Tesla Thruster Specs?
My understanding is that they will be compressed air, fed from a tank where the
rear seats would have been.
On Fri, 20 Sep 2019, 14:17 Galejs, Robert - 1007 - MITLL, <galejs@xxxxxxxxxx
<mailto:galejs@xxxxxxxxxx> > wrote:
Tesla appears to be planning some sort of cold gas thruster option for their
new roadster model…
… See https://insideevs.com/news/350682/tesla-roadster-spacex-thrusters/ for ;
example…
… but I can’t find anything definitive about what these thrusters are planned
to look like. On one car enthusiast Facebook group I subscribe to, someone was
claiming that Tesla was planning to put ten 400 lb thrusters around the vehicle
which would be capable of firing for 90 seconds, which sounds silly just
thinking about the mass of nitrogen required.
Does anyone here have any information/informed-speculation they could share
about these potential Tesla thrusters?
Thanks,
Robert
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