curious about new NASA Crew Launch Vehicle

[TWRackers]

I've been wondering about NASA's proposed Crew Launch Vehicle ( https://spaceflightnow.com/news/n0512/08clv/ ) which is basically a modified Solid Rocket Booster for the first stage, a liquid-fueled second stage using one (or more?) Space Shuttle Main Engines, and a new Apollo-like Command/Service Module with escape tower sitting on top.

What I'm curious about is how roll control of such a rocket would be accomplished. There are no fins, and with only a single motor nozzle, you have control over two axes of rotation easily enough, but not roll. The only choices I can see are (1) using reaction control thrusters on CSM, but they're optimized for use in vacuum (long nozzles), or (2) roll control is not required on such a rocket. I'm trying to think of an earlier NASA launch vehicle that had only a single first stage nozzle and no fins. None of the manned boosters fall in that category; the Mercury Redstone was the only one with a single motor, but it had fins. The Mercury Atlas had 3 nozzles plus two verniers, the Gemini Titan had two motors, and the Saturns 1B and 5 had 8 and 5 respectively.

Anybody have any other ideas?

 

[wilsotr]

Excellent question ... the CEV LV will likely have some kind of RCS module, probably between the first and second stages or "strapped on" the second stage.

 

[Nerull]

The other renders i've seen included fins.

You could also use a Soyuz style launch pad - Soyuz does not do a roll manuvre - instead the entire launchpad rotates to the correct heading before launch.

Of course, theres also the possibility of not rolling at all, but the crew might complain if they have to ride to orbit sideways or at a wierd angle.

 

[sandman]

There are attitude rockets at the top of the SRB just below the interstage strut.

 

[wilsotr]

Originally posted by sandman
There are attitude rockets at the top of the SRB just below the interstage strut.

Also a roll control system on the upper stage just above the struts. I'm not certain, but the ones on the SRB side of the adapter may actually be sep motors ... I'm not sure why you'd need two RCS systems on the launcher.

 

[TWRackers]

Originally posted by sandman
There are attitude rockets at the top of the SRB just below the interstage strut.

Neat, where'd you get that drawing?

The ones at the top of the SRB definitely look like RCS quads, I think the grey ones on the upper stage might be used to push away from the first stage before starting the motor, they might be RCS units as well.

 

[sandman]

You would need some sort of attitude control on the SRB since it doesn't have fins of a gimballed nozzle.

The Shuttle gimballs the main engines for attitude control.

 

[TWRackers]

Originally posted by sandman
You would need some sort of attitude control on the SRB since it doesn't have fins or a gimballed nozzle.

The Shuttle gimballs the main engines for attitude control.

Apparently the SRB nozzles are gimballed too. Check about 1/4 down this page, at T minus 28 seconds.

https://science.ksc.nasa.gov/shuttle/technology/sts-newsref/stsover-launch.html

 

[Nerull]

Almost all control is done by gimballing the SRBs until they are jettisoned on the Shuttle.

 

[denverdoc]

Things a dog. Just one man's opinion, but a conglomeration of mostly off the shelf stuff thrown together to keep it under the miniscule budget alloted.
J

 

[sandman]

a conglomeration of mostly off the shelf stuff thrown together to keep it under the miniscule budget alloted.

So was the Saturn 1B!

 

[jflis]

Originally posted by sandman
So was the Saturn 1B!

ya think?

 

[wilsotr]

Originally posted by denverdoc
Things a dog. Just one man's opinion, but a conglomeration of mostly off the shelf stuff thrown together to keep it under the miniscule budget alloted.
J

That's certainly one way to look at it. Of course, it can also be argued that using off-the-shelf, proven hardware is a good way to hold down costs (why re-invent the wheel?) and build on established reliability.

 

[rocketguy101]

Somebody named Rusty posted links on sci.space.history and rmr to an online NASA solicitation for CEV models. NASA released a 16-mb, 37-page MS Word document. It has highly detailed and dimensioned drawings of the CEV capsule, Lunar lander, CEV crew launcher and CEV heavy lift launch vehicle.

16-mb MS Word Document with CEV model drawings
https://prod.nais.nasa.gov/eps/eps_data/118283-SOL-001-002.doc

NASA model solicitation page

https://prod.nais.nasa.gov/cgi-bin/eps/sol.cgi?acqid=118283

 

[Countdown Hobbies]

Whos making a kit and when????

Cool looking though, I hope it or something else leads to some more moon landings

 

[danc]

I've thought about building a scratch model of the proposed cargo lifter rocket but it also has no fins. I wonder if there is a way around this to make it work. It's possible that it could fly some of the time just fine and other times be completely unstable.

 

[TWRackers]

Originally posted by danc
I've thought about building a scratch model of the proposed cargo lifter rocket but it also has no fins. I wonder if there is a way around this to make it work. It's possible that it could fly some of the time just fine and other times be completely unstable.

Direct answer: the old Estes Gemini Titan model had clear acrylic fins; a bit of a cheat, but they did the job.

Y'know, initially I would've said, "Just make sure the CG is far enough ahead of the CP, and it should be stable even if it doesn't have fins." But I've been evaluating RockSim the last few weeks, and I noticed something odd. As I started laying out a rocket, starting with the nose, then the body tube, working my way back, I was surprised that RockSim says a nose cone and 18" long body tube -- and nothing else -- is unstable. That implies if I just stuff a nose cone into a tube and fling it high enough into the air, that it would tumble back down instead of coming in nose first. It's like RockSim doesn't attribute any contribution to the CP from the body tube. And it didn't matter which CP calculation method was being used (cardboard, Barrowman, RockSim). I think I may fire off a question to Apogee Rockets (RockSim vendor) about that, and maybe a post in the relevant forum section here too.

If the body tube really contributes very little to the CP, why do tube fins work? Is it because half of the airflow past a tube fin is going inside the tube?

Yep, definitely gotta take this one to the aerodynamics subject area.

 

[marvSRG]

Originally posted by sandman
So was the Saturn 1B!

Yeah, and don't forget the Soyuz launch vehicle...they've just added on to the design that sent Sputnik up!

 

[JRThro]

Originally posted by denverdoc
Things a dog. Just one man's opinion, but a conglomeration of mostly off the shelf stuff thrown together to keep it under the miniscule budget alloted.
J

And that's a problem because...?

 

[roadkill]

Looks like NASA is finally getting the concept right; stacking the orbiter on top instead of bottom of the stack where all the falling debris will hit it....
...Shuttle is a fancy toy, but all those wings, landing gear and whatchamacallem doodads eat up on the payload capacity making it insanely expensive per pound to launch in comparison to conventional design....

 

[JRThro]

Originally posted by Countdown
Whos making a kit and when????

Cool looking though, I hope it or something else leads to some more moon landings

I believe Dr. Zooch has one called "the Stick".