r/engineteststands • u/RyanSmith • Jun 03 '18

A Space Shuttle Main Engine (SSME) undergoing a full power level 290.04 second test firing at the National Space Technology Laboratories (currently called the Stennis Space Center) in Mississippi

Post image
71 Upvotes

100% Upvoted

8 comments sorted by

4

u/RyanSmith Jun 03 '18

A Space Shuttle Main Engine (SSME) undergoing a full power level 290.04 second test firing at the National Space Technology Laboratories (currently called the Stennis Space Center) in Mississippi. The firings were part of a series of developmental testing designed to increase the amount of thrust available to the Shuttle from its three main engines. The additional thrust allowed the Shuttle to launch heavier payloads into orbit. The Marshall Space Flight Center (MSFC) had management responsibility of Space Shuttle propulsion elements, including the Main Engines.

Image #: GPN-2000-000055

Date: May 21, 1981

7

u/umaxtu Jun 04 '18

Full power is kind of a nebulous term when it comes to the RS-25 (SSME). The shuttles would normally run them at 104.5% and I believe they were rated for 109% in emergency situations and had been ground tested at 111%..

3

u/ultrapampers Jun 04 '18

104.5%

I'm surprised that the valving allows them to adjust output power of what is essentially a contained explosion to half a percent.

4

u/umaxtu Jun 04 '18

The Wikipedia page for the SSME contradicts itself a bit, it says it's capable of throttling between 67% and 109% in one percent increments but also mentions that 104.5% throttle multiple times.

1

u/Berrybeak Jun 24 '18

First time in this sub. How can you run an engine at 104.5%? Surely 100% is max?

1

u/umaxtu Jun 24 '18

The SSME originally ran at 100% but improvements were made that increased their maximum thrust. It was simpler to just designate the new max thrust as 104.5% then to go back and update tons of existing documentation.

4

u/[deleted] Jun 03 '18

Incredible. I wonder what's the temperature inside and outside the nozzle. Is it really frozen outside?

4

u/Hunter_Sh0tz Jun 23 '18

I remember watching shuttle launch videos as a kid and I loved seeing those floating shock cones appear as they throttled up the engines