Lights! Camera! Danger!

Jimmy Neutron has been busy helping the MSFC boys (and girls) genius design rockets. Or so it would appear from the looks of two decisions that have been made affecting ARES 1.

First, it appears that none of the ARES 1 crowd would be welcome at a Jimmy Buffet concert, as they are going to leave the fins at home. Rather than provide a passive system for maintaining stability during the early stages of ascent, they have opted to leave fins off the vehicle and use the SRB's active gimbal system, which is on the edge of having enough control authority to actually work as it is. They think this solution will keep life cycle costs down, as they won't be breaking fins off, or anything they attach to, when the booster his the water for recovery.

Of course, that decision costs 1100 lbs in extra propellant to keep the ship going straight up. Why so? Well, anytime that gimbal is off-center, thrust is not being generated in the straight up direction, and losses must be accounted for.

And, yes, that 1100 lbs is more than fins would weigh. Thanks for asking.

But that 1100 lbs also detracts from the rocket's overall ability to place the desired payload, ORION, into orbit itself. So enter the next decision in this Rube Goldberg line of reasoning. The second stage is a liquid propellant based system. Right after staging, and before the second stage motor is lit, the liquid oxygen and liquid hydrogen must be forced to the bottom of their respective tanks so that pick-ups can direct the liquids into their turbopumps.

So to get the liquids to the bottom of their tanks, small rockets, called ullage motors, are fired to settle the propellants. Normally these little motors are carried along for the ride after they do their job. But in this case, their extra weight, on top of the 1100 lbs for the finless wonder, also detracts from getting ORION to its intended destination.

You can almost hear our future Italian waiter yell, "I can fix that!" "Jettison the ullage motors!"

So instead of having a passive quick release on the fins as they hit the water, extra propellant is added for the steering motor on the first stage, and a jettison system is added for the second stage propellant settling system. Don't forget redundancy on that! Ooops, that's more weight. Risk accepted. Move on.

But we're not done. As reported here on RandS several weeks ago, three means of damping vibrations in the bladder basher were being considered. Now the program is finally ready to make a recommendation, and its the system we graphically depicted here back then. Small thrusters will be fired to and fro to counteract the oscillations in the SRB pipe organ.

We're not sure, but we think we saw Jimmy working on an Entropy Pump design last week as well. Heaven knows that's one device the minions perfected many years ago.