Orbiter Maneuvering Engines (nozzle dimensions, specifications)

[N_Molson]

I'm currently working on a Deltaglider-like spaceplane (so a bit too big to qualify as a minishuttle) that would use existing technology. So I'm considering using a single Space Shuttle OME engine as main propulsion.

As I know some of you work on the Space Shuttle (SSU), I'm wondering if you would share some knowledge about it. A side cutaway of the engine with dimensions would be perfect. If not available, nozzle dimensions (length, max diameter) would allow me to work with pictures.

I'm also interested by the number of restarts & throttling ability (if any), too, and other specifications relative to its operation. :tiphat:

 

[Urwumpe]

I'm currently working on a Deltaglider-like spaceplane (so a bit too big to qualify as a minishuttle) that would use existing technology. So I'm considering using a single Space Shuttle OME engine as main propulsion.

As I know some of you work on the Space Shuttle (SSU), I'm wondering if you would share some knowledge about it. A side cutaway of the engine with dimensions would be perfect. If not available, nozzle dimensions (length, max diameter) would allow me to work with pictures.

I'm also interested by the number of restarts & throttling ability (if any), too, and other specifications relative to its operation. :tiphat:

How detailled do you want it? I can't offer you perfect CAD drawings, but are the specifications beyond the SCOM enough? You did read the SCOM (Shuttle Crew Operations Manual) already?

https://www.nasa.gov/centers/johnson/pdf/390651main_shuttle_crew_operations_manual.pdf

It offers a good first overview of the crew perspective of the OME. (In chapter 2.18)

It already specifies the number of restarts (at least 1000) and operational life (15 hours of cumulative firing), the minimum burn duration is two seconds. It is not throttleable as system (no servo valves, valves only know fully closed or fully open, but have position indicators because they move slowly and can get stuck in between), but the thrust chamber should still ignite if the propellant valves are at least 70% open.

Would you like to know more?

 

[N_Molson]

That's exactly the kind of document I was looking for, thanks ! I knew you knew where to search, that will save some precious time

 

[Urwumpe]

That's exactly the kind of document I was looking for, thanks ! I knew you knew where to search, that will save some precious time

Its always the best start into the Space Shuttle topic before diving into the details.



Again (In best Starship Troopers voice): Would you like to know more? :rofl:

 

[N_Molson]

So I found the section about it ; it gives a lot of clues about its operation, but I still could use a nice cutaway (there's a pretty one of the SSME, but only perspective views of the OMS).

Also, something like a graph of ISP & Thrust vs Altitude could be interesting. Here they only say "it can provide thrust above 70,000 feet".

And well while I'm there dry mass of the engine and tanks could be useful, too. I have little idea of my spacecraft wet mass (DeltaGlider dimensions), and that will obviously decide the launch system. Maybe 30 or 35 tons...

 

[GLS]

Also, something like a graph of ISP & Thrust vs Altitude could be interesting. Here they only say "it can provide thrust above 70,000 feet".

It was designed for vacuum use, so there should be no (real) data for sea-level. The 70kft limit is where the flow starts to separate from the nozzle and it would fail from the uneven forces.

 

[Urwumpe]

Sorry, I can't find anything like that, only lots of performance data. Also, 70000 ft is really the minimum altitude, the nozzle is not designed to be safely operated at lower altitudes, because of a too high back pressure.

---------- Post added at 22:56 ---------- Previous post was at 22:55 ----------

 

[N_Molson]

Thanks. I'll start a proper thread in the add-on dev section soon (as soon I finish the first Blender "draft"). That will be the preliminary design review so to say