Re: Electrogravitics is Reality!


William.Mook@xxxxxxxxx wrote:
Tomcat doesn't realize that SRBs are used to provide additional thrust
at launch, not provide the efficient increase in speed higher
performing cryogenics provide. lol.

But just for fun let's do the calculation.

Let's assume the proposed cockpit weighs the same as a Mercury capsule,
907.2 kg.

Now the SRBs Gross Mass: 589,670 kg. Empty Mass: 86,183 kg.
Propellants: Solid Thrust(vac): 1,174,713 kgf. Isp: 269 sec. Isp (sea
level): 237 sec. Burn time: 124 sec.

Wow!

So, tomcat wants to take 4 SRBs and burn them in PARALLEL!!!! (he talks
about SSTO so they're not staged which would give slightly better
performance) under an updated version of a Mercury capsule... OUCH!
The pilot better have a chiropractor... lol.

Take off weight of the four SRB + mercury cluster would be; (hold on
let me get my spreadhseet started...)

TAKE OFF BURN OUT
2,359,587.2 345,639.2 Weight
4,698,852 4,698,852 Thrust
1.99 13.59 GEE

That puppy would put out quite a kick!!!

The specific impulse is 237 sec max. That's an exhaust velocity of;

Ve = g0 * Isp = 9.37 * 237 = 2,327 m/sec

And propellant fraction is;

u = 0.8535

which isn't too shabby... so now we can compute the IDEAL terminal
velocity of this setup;

Vf = Ve * LN(1/(1-u)) = 2,327 * LN (1/(1-.8535)) = 4,470 m/sec

Which is about HALF the speed you need.

By the way, this is essentially the same performance as a single SRB
flying from liftoff to burnout all by itself;

1.992153238 Gees at take off
13.63044916 Gees at burnout
0.853845371 Propellant fraction

4475.68455 Terminal velocity


During ascent you'd likely lose about 1,500 m/sec to gravity losses
(its more like 2,200 m/sec normally but when pulling 14 gees you gain
some advantage) so actual performance would be around 3 km/sec. The
capsule would come crashing down a little downrange from the same spot
the SRBs come crashing down after a shuttle larunch today.

Of course you can do this suborbital flight much much better with a
redstone rocket, like Al Shepard did back in the early 1960s.

If you want to get to orbit with a single stage and a minimum capsule,
I'd recommend something like the Atlas Mercury rocket used by John
Glenn back in the early 1960s. That thing had 3 rocket engines at lift
off, it dropped two on the way up, and had one sustainer which got it
to orbit. It was a balloon tank pressurized by propellant, and worked
very well as a stage-and-a-half. But we could call it SSTO today. I
always liked the idea of recovering the engines for reuse. But that's
sort of what the Space Shuttle does today - except its much bigger, and
the throw away engines are SRBs.





Yes, that was a 'fun' calculation. But mathematics can be deceptive.
Assumptions here included same flight plan as the Space Shuttle. With
the Shuttle the SRB is carrying weight and it's burn is designed for
that. It is programmed to reduce thrust at max. dynamic pressure to
protect the Shuttle, for instance.

Also, it is putting another vehicle into orbit, along with the
Shuttle's SSMEs, and that means a trajectory not meant for orbit or
sub-orbit.

All in all, with programmed max. thrust and a trajectory designed for
orbit/sub-orbit at optimum altitude you would probably have something
along the line of 9000 mile sub-orbital trajectory. Add wings and it
might get close to a full circle. With 10,000+ mph speed there is real
lift at about 150,000 feet.

But, all of this is just a little 'fun', because the spaceplane would
also have SSMEs similiar to the Shuttle so thrust would continue. I
would also have both ion and electrogravitic propulsion to further
assist with breaking gravitational bonds.

Enjoyed the calculation though. And, those SRBs will definitely help
get a "fat albert" off the runway.



tomcat

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