Author Topic: Delta IV Q&A  (Read 156082 times)

Offline TetraOmni

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Re: Delta IV Q&A
« Reply #600 on: 05/25/2015 12:48 PM »
Hi, i have some questions about the Delta 4:
 
Why is it being retired instead of being evolved into a less costly rocket? Basically ULA has this great vehicle and are going to just throw it away! F9 had to evolve to meat the commercial market, why not D4?

Gotta be cheaper than developing Vulcan from scratch^.^

Online kevin-rf

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Re: Delta IV Q&A
« Reply #601 on: 05/25/2015 01:01 PM »
In reality, Vulcan is that evolution.
I just saw some idiot at the gym put a water bottle in the pringles holder on the treadmill.

Online edkyle99

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Re: Delta IV Q&A
« Reply #602 on: 05/25/2015 04:17 PM »
Hi, i have some questions about the Delta 4:
 
Why is it being retired instead of being evolved into a less costly rocket? Basically ULA has this great vehicle and are going to just throw it away! F9 had to evolve to meat the commercial market, why not D4?

Gotta be cheaper than developing Vulcan from scratch^.^
The company that builds Delta 4 already has a lower-cost alternative for all but the Heavy missions (Atlas 5).  Last year it considered increasing the Delta 4 production rate to offset the RD-180 issue, but soon switched to the plan to develop Vulcan instead.  Presumably Vulcan will cost less than Delta 4 over its life, including development costs.

Atlas 5/Vulcan already has a better upper stage (Centaur).  Delta 4 would need a vastly improved first stage (cost and performance) to survive.  That means a new main engine, which means just as much development as Vulcan.   

 - Ed Kyle

Offline baldusi

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Re: Delta IV Q&A
« Reply #603 on: 05/25/2015 04:31 PM »
Hi, i have some questions about the Delta 4:
 
Why is it being retired instead of being evolved into a less costly rocket? Basically ULA has this great vehicle and are going to just throw it away! F9 had to evolve to meat the commercial market, why not D4?

Gotta be cheaper than developing Vulcan from scratch^.^
Delta IV is not that great. You can't get Atlas V 431/531/541/551 performance with a single stick. The integration process is longer and more expensive. Also, it has less launch rate per pad. It needs two different upper stages and there's a reason that the Common Upper Stage is based on Centaur. Its avionics were replaced with Atlas'. It had a lot of different fairings. You need at least four different cores models to offer the full performance design. It's not human rated. And its engine is ablatively cooled and thus has no reuse potential. Also its manufacturer has a lot of overhead because it was designed to mount on the SSME infrastructure. And there are no equivalent engines in the world to replace it with like they are able to with the RD-180.

Offline Patchouli

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Re: Delta IV Q&A
« Reply #604 on: 05/26/2015 01:21 PM »

Delta IV is not that great. You can't get Atlas V 431/531/541/551 performance with a single stick. The integration process is longer and more expensive. Also, it has less launch rate per pad. It needs two different upper stages and there's a reason that the Common Upper Stage is based on Centaur. Its avionics were replaced with Atlas'. It had a lot of different fairings. You need at least four different cores models to offer the full performance design. It's not human rated. And its engine is ablatively cooled and thus has no reuse potential. Also its manufacturer has a lot of overhead because it was designed to mount on the SSME infrastructure. And there are no equivalent engines in the world to replace it with like they are able to with the RD-180.

Keep in mind the Areojet SRBs on the Atlas have about seven and a half tons more propellant then the GEM 60s on the Delta IV M+ and  may be responsible for a good deal of the performance difference.
« Last Edit: 05/26/2015 01:25 PM by Patchouli »

Online pippin

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Delta IV Q&A
« Reply #605 on: 03/19/2017 02:14 PM »
In this image of the WGS-9 launch you can see that the Delta IV boosters have different aft skirts.
Why is that?

https://twitter.com/johnkrausphotos/status/843299763747479553

« Last Edit: 03/19/2017 02:17 PM by pippin »

Offline DatUser14

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Re: Delta IV Q&A
« Reply #606 on: 03/19/2017 02:16 PM »
In this image of the WGS-9 launch you can see that the Delta IV boosters have different aft skirts.
Why is that?

https://twitter.com/johnkrausphotos/status/843299763747479553
One pair has a fixed nozzle, the other pair has a gimballed nozzle. I don't know which is which.
Where can I apply for SpaceX fanboy?.

Online pippin

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Re: Delta IV Q&A
« Reply #607 on: 03/19/2017 02:17 PM »
Ah, thanks!

Offline Jim

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Re: Delta IV Q&A
« Reply #608 on: 03/19/2017 10:27 PM »
In this image of the WGS-9 launch you can see that the Delta IV boosters have different aft skirts.
Why is that?

https://twitter.com/johnkrausphotos/status/843299763747479553
One pair has a fixed nozzle, the other pair has a gimballed nozzle. I don't know which is which.

The one will the longer skirt has TVC

Online pippin

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Delta IV Q&A
« Reply #609 on: 03/19/2017 10:35 PM »
Thanks again.
Once you know it it's quite obvious how different the exhaust directions are for the different boosters.

Do the ones with TVC usually fire at less of an angle at liftoff? To decrease cosine losses or to limit the effect on the pad?

Is the impact of plume impingement lower at liftoff than at altitude so that they can simply do it?
« Last Edit: 03/19/2017 10:37 PM by pippin »

Offline MATTBLAK

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Re: Delta IV Q&A
« Reply #610 on: 03/19/2017 10:57 PM »
Has anyone ever published good, worked-out performance figures for a version of the single-stick with 8x GEM-60 solids, aluminum-lithium structures and the 5-meter D-IVH upper stage? And with a regenerative RS-68 prospect and all the above gear? :) I'm willing to bet performance closing in on the Delta IV-Heavy, even with the standard RS-68A engine, and cheaper than the Heavy to boot.
« Last Edit: 03/19/2017 10:57 PM by MATTBLAK »
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Offline sdsds

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Re: Delta IV Q&A
« Reply #611 on: 03/20/2017 03:02 AM »
Has anyone ever published good, worked-out performance figures for a version of the single-stick with 8x GEM-60 solids, aluminum-lithium structures and the 5-meter D-IVH upper stage? And with a regenerative RS-68 prospect and all the above gear? :) I'm willing to bet performance closing in on the Delta IV-Heavy, even with the standard RS-68A engine, and cheaper than the Heavy to boot.

Sorry I don't know the answer to your question but am responding anyway! ;)

I think maybe no serious consideration has been given to 8x solids on DIV because one or more of:
- mounting 8x solids would require somewhat major modifications to the pads;
- supporting the loads would require a redesign of the core, interstage, upper stage, etc.
- DIV-H exists;
- Atlas V exists;
- Vulcan is in development.
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Offline MATTBLAK

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Re: Delta IV Q&A
« Reply #612 on: 03/20/2017 09:23 AM »
Delta with 8x solids should outperform Atlas V-551. I was recently told by someone who knows these things that 8x GEM-60 solids would be the most that could be accommodated with Delta on the corestage without major redesign, and even then the corestage engine would likely have to run a different throttling profile. The 8x solid concept was looked at early in the Delta's career but was abandoned early on. Anyway, if they ever were to continue with Delta; 4x better solids such as the GEM-63XL would suffice over 8x GEM-60s. But with Vulcan on the horizon, the mighty RS-68 will be retired and the Delta IV tooling heritage will live on with Vulcan.
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Online edkyle99

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Re: Delta IV Q&A
« Reply #613 on: 03/20/2017 01:13 PM »
But with Vulcan on the horizon .... Delta IV tooling heritage will live on with Vulcan.
Maybe.  Maybe not.  Some hints have suggested that Vulcan diameter could grow fatter than Delta 4, to as much as 5.4 meters, the same as the payload fairing.  Meanwhile, a 2 x AR-1 version, if that should happen, would likely be 3.81 meters (150 inches) in diameter, the same as the Atlas 5 CCB.

 - Ed Kyle
« Last Edit: 03/20/2017 02:59 PM by edkyle99 »

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