Gemini-Titan Vibrations Were Worse than Ares I

[JimMcDade]

This is a letter to the editor from my latest copy of Aviation Week & Space Technology:

The Art of Simplicity

Aviation Week & Space Technology

09/01/2008 , page 8

Greg De Santis

The Villages, Fla.

The problem of thrust oscillation on the Orion/Ares I is not too different from the oscillation problem on the Gemini/Titan system. In that case, the longitudinal vibration was so bad the astronauts could not see the instruments during the first 30 sec. of launch. The solution didn’t take months of meetings and vu-graphs, and it didn’t require adding 6,500 lb. of extra weight to the Titan. NASA simply sent astronaut Ed White to Ames to find a solution. We bolted a Gemini seat into the five-degree-of-freedom centrifuge, programmed the analog computers to simulate the vibration, and set about designing a damper to attach to the seat. The whole task from Ed’s arrival to finished design took less than three weeks. White flew our design on Gemini 4.

We did have a number of advantages though: No contractors or “bean counters” were involved; we used 20-in. slide rules and K&E drafting equipment; a Mark’s Handbook; the best machine shop and machinists in the government; and a couple of young engineers who believed that working for NASA was the best job in the world.

Look to the simplest solution.

[J.McDonald]

What does that 6,500lbs refer to?

EDIT: Just found out on other thread

[Me2]

This is a letter to the editor from my latest copy of Aviation Week & Space Technology:

The Art of Simplicity

Aviation Week & Space Technology

09/01/2008 , page 8

Greg De Santis

The Villages, Fla.

The problem of thrust oscillation on the Orion/Ares I is not too different from the oscillation problem on the Gemini/Titan system. In that case, the longitudinal vibration was so bad the astronauts could not see the instruments during the first 30 sec. of launch. The solution didn’t take months of meetings and vu-graphs, and it didn’t require adding 6,500 lb. of extra weight to the Titan. NASA simply sent astronaut Ed White to Ames to find a solution. We bolted a Gemini seat into the five-degree-of-freedom centrifuge, programmed the analog computers to simulate the vibration, and set about designing a damper to attach to the seat. The whole task from Ed’s arrival to finished design took less than three weeks. White flew our design on Gemini 4.

We did have a number of advantages though: No contractors or “bean counters” were involved; we used 20-in. slide rules and K&E drafting equipment; a Mark’s Handbook; the best machine shop and machinists in the government; and a couple of young engineers who believed that working for NASA was the best job in the world.

Look to the simplest solution.

That isn't totally true. That didn't solve the problem. The Titan had to be modified and tested before NASA used it.

http://www.hq.nasa.gov/office/pao/Hi...4203/ch7-2.htm
http://www.hq.nasa.gov/office/pao/Hi...4203/ch8-2.htm

[JimMcDade]

That isn't totally true. That didn't solve the problem. The Titan had to be modified and tested before NASA used it.

http://www.hq.nasa.gov/office/pao/Hi...4203/ch7-2.htm
http://www.hq.nasa.gov/office/pao/Hi...4203/ch8-2.htm

The relevant point is that the Gemini-Titan vibration problem was more severe than the Ares I vibration in terms of duration and timing in spite of the unsubstantiated claims made by the DIRECT 2.0 conspiracy theorists. The Ares I vibration might blur the vision of astronauts during the final few seconds prior to staging. The GT vibrations began at liftoff and continued for about half of one minute.

We all know that the Titan was an ICBM that required a fair bit of modification to man-rate.

[J.McDonald]

If the Gemini-Titan oscillation prbolems were worse than Ares-I, yet solved by the use of seat dampeners, why are NASA looking to install 6,500lbs of active dampening in the LV?

[space_boy54]

The installation of seat dampers would increase the re-entry weight of the Orion capsule.

[J.McDonald]

That makes sense, especially as Orion has to go all the way to the moon and back. How heavy would seat dampers be? I just sort of presumed that if Gemini could soak up the extra mass, it couldn't be all that much.
Is there an advantage in putting the dampening system 'down the chain' so that it protects the upper stage and paylaod, rather than just the crew themselves? Or are the oscillations not any concern to the hardware?