33 votes
Accepted

Why is the Delta IV Heavy taller than the Delta IV Medium?

The fairing is bigger (Taller) for larger payloads.
geoffc's user avatar
  • 79.2k
22 votes
Accepted

Why isn't the Delta IV Heavy ever used for crewed spaceflight?

What's the reason that they don't use the Delta Heavy for crewed flights to the Moon and beyond? The Delta IV Heavy isn't powerful enough to send Orion beyond low Earth orbit. Orion masses about 26.5 ...
Russell Borogove's user avatar
18 votes
Accepted

Who built the sparklers used by the Shuttle program during launch?

In the late 70's and early 80's I worked for a company named Unidynamics Defense Systems. We provided this subassembly. We were not the design originators, this design I am quite sure came from NASA. ...
D.S. Harvey's user avatar
12 votes
Accepted

Could a Delta 4 Heavier be built?

Here are the projected Delta Heavy upgrades from United Launch Alliance (ULA) in different configurations. You can see that the payload value at the name of the rocket version is not the same as the ...
Mark777's user avatar
  • 2,145
11 votes
Accepted

Why are some rockets orange?

From perusing online, it seems there's a consensus that the insulating foam is just that color. They painted the Delta II, but stopped painting due to the added weight. As to why they painted the ...
Arthur Dent's user avatar
  • 1,135
10 votes

How does the Parker Solar Probe have such a wide launch window?

There is some information in this paper although it does not directly address your question. It does mention that the first Venus flyby is at a relatively high altitude (about 2500 km) which may make ...
Steve Linton's user avatar
  • 19.6k
9 votes

Could a Delta 4 Heavier be built?

There are a number of differences between the two systems. One of them is the cross-feed system of the Falcon Heavy. The cross-feed is only expected to be used on the Falcon Heavy with the heaviest ...
PearsonArtPhoto's user avatar
  • 121k
9 votes

How can the same upper stage be optimal on a common core booster as well as on a single booster?

You haven't defined "optimal" here. The commercial launch business is more concerned with cost optimization than mass optimization. Atlas V offers two variants of Centaur, with one or two RL10 ...
Russell Borogove's user avatar
7 votes

Velocity of the Parker Probe when it will be given final boost by the rocket?

At 9 hours after launch, the Parker Space Probe's current speed is about 12.4 km/s with respect to the center of the Earth. This is smaller than it was a bit over 8 hours ago when the third stage burn ...
David Hammen's user avatar
  • 73.8k
6 votes

Why can't Falcon Heavy accelerate deep space payloads as fast as Atlas V and Delta Heavy?

The short answer is that the Isp of the Falcon's RP-1/LOX upper stage engines is much less than the Atlas V's LH/LOX. The primary metric of interest is $\Delta v$, which depends on $I_{sp}$ and mass ...
RickNZ's user avatar
  • 546
6 votes

Why do RS-68s suffer ignition failures?

Partial answer (covering By what mechanism do RS-68s light?): The RS-68 uses electrically fired solid-propellant igniters in the gas generator and main combustion chamber. It also uses a helium spin ...
Organic Marble's user avatar
6 votes

Velocity of the Parker Probe when it will be given final boost by the rocket?

Technically this answer doesn't specify what slows it down, but it does explain how it does. I've never done anything with orbital mechanics before today, but I got bored and read a few articles, ...
Magic Octopus Urn's user avatar
6 votes

How does the Parker Solar Probe have such a wide launch window?

New launch schedule: Rescheduled to lift off at 3:31 a.m. EDT on Aug. 12, 2018. Scrub Announcement Video: "Parker Solar Probe Launch Postponed". There will be live coverage on the NASA ...
Rob's user avatar
  • 3,256
5 votes
Accepted

Velocity of the Parker Probe when it will be given final boost by the rocket?

I added this to a special page to Where is Roadster, you can find the Parker Solar Probe info here. The current location is 7,338,815 miles (11,810,682 km, 0.079 AU) from Earth, moving away from ...
PearsonArtPhoto's user avatar
  • 121k
5 votes

How is imbalance handled in the Delta IV heavy?

The engines on the Delta IV Heavy, like most large liquid-fueled engines, can gimbal, vectoring up to 6º in any direction, so any mass imbalance can be corrected for almost instantly. That said, it ...
Russell Borogove's user avatar
5 votes

What does the US Govt get out of its Assured Access funding of ULA?

The goals of Assured Access to Space are (PDF of a hearing by the House Committee on Armed Services, page 14): The existing policy, codified in federal law, requires that assured access policy ...
Hobbes's user avatar
  • 127k
5 votes

Who built the sparklers used by the Shuttle program during launch?

Problems Starting Space Shuttle Engines Prior to the first flight of the Space Shuttle we were test firing the Main Propulsion System Engines at the test site in Mississippi when we experienced a ...
Harvey LeBlanc's user avatar
5 votes

What makes Falcon Heavy with 3 booster 4 times more capable than single booster F9?

https://en.wikipedia.org/wiki/Falcon_9 Falcon 9 payload to LEO: 22.8tons to GTO: 8.3tons https://en.wikipedia.org/wiki/Falcon_Heavy Falcon Heavy payload to LEO: 63.8tons to GTO: 26.7tons ...
Marcelo Pacheco's user avatar
5 votes
Accepted

What is the blue/red flare at the Delta IV Heavy launchpad

The answers on the reddit thread you linked are essentially correct. The camera angle is the only difference between the two images, making the flare appear further away. As you mention, Delta IV and ...
Jack's user avatar
  • 9,976
5 votes

How does the Parker Solar Probe have such a wide launch window?

You are correct in your assumption that larger launch windows require higher fuel margins on the rocket. Therefore, the main reason for such a large launch window is not because they just want to, but ...
DaGroove's user avatar
  • 1,334
3 votes
Accepted

What is the current status of delta IV heavy 7 (in 2017)?

ULA presented the 6-booster "Delta Superheavy" in 2004 (archive link) as a possible upgrade path for the Delta IV. As far as I can tell, it's only a proposed design. Actually building it would ...
Russell Borogove's user avatar
3 votes
Accepted

Delta IV Heavy trans-lunar injection mass

According to John Schilling's calculator, Delta IV Heavy should be able do about 9.8 tons to TLI (defined as a 185km perigee, 400000km apogee Earth orbit). Because of the nonlinearity of the rocket ...
Russell Borogove's user avatar
3 votes

Who built the sparklers used by the Shuttle program during launch?

According to descriptions in the KSC's Mission Preparation and Prelaunch Operations and the Launch Pad/Mobile Launcher Platform Interfaces pages, the hydrogen burn-off system for the Shuttle was ...
Timpanus's user avatar
  • 167
3 votes
Accepted

Feasibilities and challenges of these Orion + commercial lunar lander scenarios?

Robert Zubrin of Mars Direct fame has discussed the issue of how to return to the Moon, to stay, to do ISRU (In Situ Resource Utilization) all without the need for neither SLS nor the Lunar Toolbooth ...
geoffc's user avatar
  • 79.2k
3 votes
Accepted

Are the Delta IV Heavy’s attachments for SRBs removable?

I haven't been able to find much explicit language about the actual attachment points, but I have found some images that convince me that the boosters are prepared specially for only the number of ...
Erin Anne's user avatar
  • 10.8k
2 votes

What is the point of launching EM-1 on DIVH/F9H?

what of the original purpose of EM-1 would be served...? It is hard to tell from the NASA administrator's comments in Ars Technica's Here’s why NASA’s administrator made such a bold move Wednesday: &...
uhoh's user avatar
  • 149k
2 votes
Accepted

Why would rocket bodies use specifically ablative coatings to reduce boil-off of cryogenic propellants? Is ablation important for this?

The ablator is more to protect the structure itself than the propellant quality/boil-off. Ablator was used in certain areas of the shuttle External Tank for this reason. This quote from "A Technical ...
Organic Marble's user avatar
2 votes

Can a Delta IV Medium fairing be put on a Delta IV Heavy for small payloads?

tl;dr the company did not offer that configuration The Delta IV User's Guide did offer two different fairings for the Heavy vehicle, one of which was 0.7 meters shorter than the other. However, ...
Organic Marble's user avatar
1 vote

Why isn't the Delta IV Heavy ever used for crewed spaceflight?

Additional to the mass problem Russell Borogove explained, there is a certification problem: Putting "manned" or "crewed" in the specification book of Launcher results in having a lot more by number ...
CallMeTom's user avatar
  • 3,308

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