LIVE: H-IIB launch with HTV-1 - September 10, 2009

[JosephB]

*This* is how Delta IV should have been developed, how a liquid hydrogen core stage is supposed to be used.  H-2B is a pocket monster.  It can lift 8 tonnes to GTO - as much as an Atlas V-541, way more than any Delta IV Medium or Proton or Zenit, and approaching Ariane 5 territory.  Those powerful SRB-A motors are the key element in this design. 

 - Ed Kyle

Excellent point Ed. They have quite a capability there with H-2B.
If the 37A Pad is ever built wouldn't it be wise to make it capable of accommodating solid strap on's for the 2 CBC's down the road some day?

Edit: Or all 3 CBC's?

[sdsds]

*This* is how Delta IV should have been developed, how a liquid hydrogen core stage is supposed to be used.  H-2B is a pocket monster.  It can lift 8 tonnes to GTO - as much as an Atlas V-541, way more than any Delta IV Medium or Proton or Zenit, and approaching Ariane 5 territory.  Those powerful SRB-A motors are the key element in this design. 

 - Ed Kyle

Yes ... very impressive!  Not only the success with the first HII-B launch, but the smooth evolution from HII-A.  It is interesting to note that of the 15 HII-A launches, the only failure was due to an SRB-A failing to separate.  Apparently they have that problem fixed!

The upgrade path -- from HII-A with one core engine to HII-B with two core engines -- sure seems attractive.  Is there a plausible Delta-IV upgrade path like that?  Or does something in the RS-68 preclude it somehow?

[catfry]

On the face of it you would want to minimize number of engines since they are the most expensive component, and to minimize complexity, however the economies of scale might make production of two smaller engines cheaper than one big.

I'd guess all else being equal, two engines have a worse mass / thrust fraction.

[sdsds]

On the face of it you would want to minimize number of engines since they are the most expensive component, and to minimize complexity, however the economies of scale might make production of two smaller engines cheaper than one big.

I'd guess all else being equal, two engines have a worse mass / thrust fraction.

I can see that makes sense if you are doing a "clean slate" design.  But Mitsubishi already has the engine for the HII-A in production.  For the flight rates planned for HII-B (is it just one a year?) it might be more economical to cluster two engines from the existing production line, rather than designing and starting up production of a new engine.

[catfry]

You are exactly right.

[edkyle99]

The upgrade path -- from HII-A with one core engine to HII-B with two core engines -- sure seems attractive.  Is there a plausible Delta-IV upgrade path like that?  Or does something in the RS-68 preclude it somehow?

Delta IV already has plenty of liquid core thrust, but its strap on boosters are wimpy compared to the H-IIA/B SRB-A motors.  SRB-A uses 65 tonnes of propellant, produces 230 tonnes of thrust in vacuum, and burns for 100 seconds.  Delta IV GEM-60s have only 17 tonnes of propellant, produce an average 88 tonnes vacuum thrust, and burn for 78 seconds.  SRB-A, a single-segment motor (heaviest currently flying, though soon to be eclipsed), is about twice as powerful as the largest existing U.S. monosegment motor (those used by Atlas V). 

Strapping something like a set of SRB-A motors to a single-core Delta IV Medium would make quite a rocket.  That's your upgrade right there.

 - Ed Kyle

[Art LeBrun]

No lessons/benefits applicable from Titan 3C 44 years ago? Ariane 42/44?

[zaitcev]

*This* is how Delta IV should have been developed, how a liquid hydrogen core stage is supposed to be used.  H-2B is a pocket monster.  It can lift 8 tonnes to GTO - as much as an Atlas V-541, way more than any Delta IV Medium or Proton or Zenit, and approaching Ariane 5 territory.  Those powerful SRB-A motors are the key element in this design.

Bah, another expensive expendable. Wake me up when they replace those SRBs with flyback kerosene boosters.
-- Pete

[Art LeBrun]

Just like heavy chemical batteries and piston engines I suspect expendable SRBs will always be with us.............no flyback liquid boosters in sight.

[daveglo]

Congrats to our Japanese partners on a successful launch.  I agree with the other folks that I can't wait to see the HTV do it's on-orbit ops.

I'll also throw in my $0.02 to agree with Ed on comments regarding the SRB design ideas.  Everybody has good ideas, and the serious scale of the SRBs is one that our engineers should be paying attention to a little closer.  Sure gave that H-IIB a swift kick in the rear off the pad!

[JosephB]

The upgrade path -- from HII-A with one core engine to HII-B with two core engines -- sure seems attractive.  Is there a plausible Delta-IV upgrade path like that?  Or does something in the RS-68 preclude it somehow?

SRB-A, a single-segment motor (heaviest currently flying, though soon to be eclipsed).....

Just curious to know what will be the eclipsing the SRB-A? And by how much? Thanks.

[catfry]

The VEGA rocket first stage will be larger. I think it is single cast. Not exactly a strap-on booster but I think it applies. It will be 88 metric tonnes of prop, thrust of 337 short tons or thereabouts, burn time 107 seconds. According to wiki, caveat emptor.

[bolun]

The VEGA rocket first stage will be larger. I think it is single cast. Not exactly a strap-on booster but I think it applies. It will be 88 metric tonnes of prop, thrust of 337 short tons or thereabouts, burn time 107 seconds. According to wiki, caveat emptor.

Same data in ESA webpage:

Height: 10.5 m
Diameter: 3 m
Propellant mass: 88 tonnes
Thrust (max): 3040 kN
Nozzle expansion ratio: 16
Burn time: 107 s

http://esamultimedia.esa.int/multimedia/vega/first_stage.html

Little changes in Avio webpage:

It is the first stage of the Vega launcher. It is currently the largest monolithic engine ever built that uses solid propellant technology of Filament Winding.

Length of the engine: 10.1m
Diameter: 3m
Mass of propellant: 88ton
Engine mass: 6,950kg
Mass of the engine housing: 3,350kg
Average of the Thrust: 2,100kN
Specific impulse: 280s
Combustion time: 106s

http://www.aviogroup.com/en/catalog/space/lanciatore_vega/motore_p_80

[Jim]

*This* is how Delta IV should have been developed, how a liquid hydrogen core stage is supposed to be used.  H-2B is a pocket monster.  It can lift 8 tonnes to GTO - as much as an Atlas V-541, way more than any Delta IV Medium or Proton or Zenit, and approaching Ariane 5 territory.  Those powerful SRB-A motors are the key element in this design. 

 - Ed Kyle

Both EELV's were originally designed without SRM's, which was per an USAF requirement.   The commercial market changed and the EELV's had to adapt but it was when they were far into their design cycles.  Hence the asymmetrical mounting of SRM's on Atlas and lack of SRM on two sides of the DIV.  .  Also, Atlas would have not used an avionics pod design which took up an SRM mounting spot.  Both the DIV MST and AV VIF had to be modified to handle SRM's and there are some compromises.  Also pad limitations prevented SRM's from being mounted in certain places on the vehicles.

[Jim]

The upgrade path -- from HII-A with one core engine to HII-B with two core engines -- sure seems attractive.  Is there a plausible Delta-IV upgrade path like that?  Or does something in the RS-68 preclude it somehow?

No, the vehicle structure would preclude it.

[JosephB]

*This* is how Delta IV should have been developed, how a liquid hydrogen core stage is supposed to be used.  H-2B is a pocket monster.  It can lift 8 tonnes to GTO - as much as an Atlas V-541, way more than any Delta IV Medium or Proton or Zenit, and approaching Ariane 5 territory.  Those powerful SRB-A motors are the key element in this design. 

 - Ed Kyle

Both EELV's were originally designed without SRM's, which was per an USAF requirement.   The commercial market changed and the EELV's had to adapt but it was when they were far into their design cycles.  Hence the asymmetrical mounting of SRM's on Atlas and lack of SRM on two sides of the DIV.  .  Also, Atlas would have not used an avionics pod design which took up an SRM mounting spot.  Both the DIV MST and AV VIF had to be modified to handle SRM's and there are some compromises.  Also pad limitations prevented SRM's from being mounted in certain places on the vehicles.

Jim, DIV is an extremely capable vehicle as is, but with hindsight being 20/20 what are some things you notice that would have improved the current vehicle. In other words, if the program could have a "do over" what would be some of the recommendations you would make? In particular, to DIVH and solids (if at all?) Thanks.

[Nick L.]

The RS-68 undershot on performance, and the tanks are too small, which caused it to miss the 10,000lb to GTO target for D-IV Medium. So I imagine, if you were to do a "do-over", you would try to get the tanks to the right size or improve RS-68 performance. (the projected RS-68A upgrade brings the Medium above 10K lbs to GTO)

Also, the CBCs, despite their name are not as common as hoped - the Medium had to be lightened to improve performance and so several large parts (like the centerbody) are different from the others. Also the H2 tank is different depending on if there are SRMs or not, and the thrust structure varies for SRM mount points, Heavy strap on mount points, etc. So if you wanted to do it over, you would make the CBC more "common" across the range. Again, I heard somewhere ULA is proposing a "common" CBC based on the M+(5,4) core which would alleviate this issue.

[bobthemonkey]

I think the more common CBC is dependant on the RS-68A to make up for the performance hit to the lighter configs due to the heavier structure.

[rdale]

I think the more common CBC is dependant on the RS-68A to make up for the performance hit to the lighter configs due to the heavier structure.

How many RS-68A's are in the HTV?

[Skyrocket]

How many RS-68A's are in the HTV?

None