Impulse Space

[RDMM2081]

One of his interviews today he said Deneb is staged combustion

[TrevorMonty]

What do we think the Deneb engine is likely to be like? I'm assuming an expander cycle would be a great fit, but electric pumped might work too.
Knowing Tom Mueller's background, what do we think is the most likely?

For electric pump 5klbs is about limit before turbopump engines are better option. Deneb is 15klbs.

[Zed_Noir]

One of his interviews today he said Deneb is staged combustion

Unlikely to be FFSC or ORSC, that leaves FRSC as the mostly likely engine type.

AIUI. FFSC is much harder with a small engine. ORSC engines requires exotic materials and complicated manufacturing processes.

List of Acronyms:
FFSC = full flow stage combustion
FRSC = fuel rich stage combustion
ORSC = oxidizer rich stage combustion

[Kaputnik]

One of his interviews today he said Deneb is staged combustion

Interesting. Expander works really well at small scales and is simple and reliable.

What's the advantage of staged? Higher T:W maybe? Or does expander not really work well with CH4?

[Asteroza]

I get the feeling Helios is targeting the Artemis TLI crowd and not so much HEO/GEO, at least for "commercial" space...

[sdsds]

Regarding Deneb:
Methalox Staged Combustion Cycle

[ZachF]

One of his interviews today he said Deneb is staged combustion

Interesting. Expander works really well at small scales and is simple and reliable.

What's the advantage of staged? Higher T:W maybe? Or does expander not really work well with CH4?

Staged combustion could let you get stupid high expansion ratios for the same engine bell size… like >500:1 if they wanted. Higher ER = higher ISP.

[ZachF]

Because ultimately you can get power and cooling and perhaps globally accessible data via lasers for cheaper than terrestrial.

LOL, ok. At this point let's just agree to disagree because we aren't even in the same solar system in terms of world view.

Have you updated your worldview on this? Just run some numbers. Starlink gen2s may cost around $100/kg. Starlink v1 was $1000/kg.

They’re using commodity solar cells probably costing about 20-30¢/Watt, and using a German built stringer (used for making commodity terrestrial utility scale solar modules for 30-40¢/Watt) to solder them up into spacecraft arrays. They’re not manufacturing the satellites by 3D printing or expensive CNC machining, but by mass manufacturing stamped metal or molding, like how you mass-manufacture automobiles. We ARE in a different solar system already…

I think I made a thread about this years ago and most people called me crazy lol.

What’s the cost of in-space solar power with <$0.30 watt solar PV and <$100/kg to LEO? Probably almost laughably cheap…

[ParabolicSnark]

What do we think the Deneb engine is likely to be like? I'm assuming an expander cycle would be a great fit, but electric pumped might work too.
Knowing Tom Mueller's background, what do we think is the most likely?

For electric pump 5klbs is about limit before turbopump engines are better option. Deneb is 15klbs.

I remember that being the case around 2015, but is that still the case? Has battery and controller technology advanced enough in the past decade (that hurts to say) where maybe it would now trade favorably at the 10-15k lb range? EV's have given us a lot in that sector.

[TrevorMonty]

10-15k might be upper limit now. Give Toms background a turbopump engine is better path.

[Tywin]

Because ultimately you can get power and cooling and perhaps globally accessible data via lasers for cheaper than terrestrial.

LOL, ok. At this point let's just agree to disagree because we aren't even in the same solar system in terms of world view.

Have you updated your worldview on this? Just run some numbers. Starlink gen2s may cost around $100/kg. Starlink v1 was $1000/kg.

They’re using commodity solar cells probably costing about 20-30¢/Watt, and using a German built stringer (used for making commodity terrestrial utility scale solar modules for 30-40¢/Watt) to solder them up into spacecraft arrays. They’re not manufacturing the satellites by 3D printing or expensive CNC machining, but by mass manufacturing stamped metal or molding, like how you mass-manufacture automobiles. We ARE in a different solar system already…

I think I made a thread about this years ago and most people called me crazy lol.

What’s the cost of in-space solar power with <$0.30 watt solar PV and <$100/kg to LEO? Probably almost laughably cheap…

And sorry I don't follow this conversation, can you explain your point?

[deltaV]

If you have a super-cheap two-stage fully reusable superheavy that can put (say) 200 tonne into LEO, then its payload can be a 100-tonne expendable kick stage with a 100-tonne actual payload. I think this beats Vulcan Centaur, except for the minor fact that it does not exist. Think of it as a one-off "tug".

From the rocket equation in a spreadsheet and a bunch of wild guesses at parameters I'd guess Starship plus Helios could get around 19 tonnes direct GEO, 37 tonnes to TLI, or 22 tonnes to low lunar orbit. That TLI figure is more than any current rocket other than SLS with EUS can do. A 100 tonne class kick stage or propellant transfer would of course make Starship even more capable (100+ tonnes to GEO, TLI or LLO) but Starship + Helios is already quite capable.

(https://www.impulsespace.com/updates/impulse-space-unveils-design-specifications-for-helios has one very important fact about Helios: it has up to 14 tonnes of propellant.)

[sdsds]

From the rocket equation in a spreadsheet and a bunch of wild guesses at parameters I'd guess Starship plus Helios could get around 19 tonnes direct GEO, 37 tonnes to TLI, or 22 tonnes to low lunar orbit.

Out of curiousity, for LLO what assumptions did you make about methalox boil-off rates? The Impulse website makes no mention of LLO as a destination orbit....

[deltaV]

Out of curiousity, for LLO what assumptions did you make about methalox boil-off rates? The Impulse website makes no mention of LLO as a destination orbit....

I didn't account for boil-off or the mass of anti-boil-off hardware such as sun shields.

Now that you mention it I wonder if boil-off is why their stated GEO performance isn't as good as I expected.

[illectro]

Plenty of numbers from Tom himself - 13.5T of propellent
Adds 3.9km/sec dv for a 6065kg payload
& 5.25 km/sec for 3241kg payload

Specific impulse is close to 378s

https://x.com/lrocket/status/1747742865424535565?s=20

https://x.com/lrocket/status/1747801633881485536?s=20

https://x.com/Phrankensteyn/status/1748115917395874108?s=20

[Robotbeat]

Plenty of numbers from Tom himself - 13.5T of propellent
Adds 3.9km/sec dv for a 6065kg payload
& 5.25 km/sec for 3241kg payload

Specific impulse is close to 378s

https://x.com/lrocket/status/1747742865424535565?s=20

https://x.com/lrocket/status/1747801633881485536?s=20

https://x.com/Phrankensteyn/status/1748115917395874108?s=20

notbadface.jpg

[sdsds]

Referencing here a comment on the Griffin Plan thread:

If Helios had long-duration capability, it could serve as a service module for Dragon launched on Falcon Heavy.

This certainly renews my interest in Helios as a potential candidate to provide propulsion for lunar orbit insertion. In that context, long-duration means only about 4 days, with acceptable boil-off rates. Have Mueller or Impulse Space provided any hints at all on that?

[Robotbeat]

10-15k might be upper limit now. Give Toms background a turbopump engine is better path.

It's a staged combustion engine.

[deltaV]

Referencing here a comment on the Griffin Plan thread:

If Helios had long-duration capability, it could serve as a service module for Dragon launched on Falcon Heavy.

This certainly renews my interest in Helios as a potential candidate to provide propulsion for lunar orbit insertion. In that context, long-duration means only about 4 days, with acceptable boil-off rates. Have Mueller or Impulse Space provided any hints at all on that?

It seems sub-optimal to have all the cost and complexity of a low-boil-off pump-fed cryogenic stage but use it for only the ~1 km/s of delta vee that it takes to enter low lunar orbit. (Dr. Griffin's plan has the same issue.) It's more usual to use fewer and bigger cryogenic stages each providing 3+ km/s of delta vee. Bigger stages like Centaur V and the Falcon 9 upper stage seem better for crewed lunar missions since you can get more delta vee out of them. If you want to use Impulse Space hardware in a crewed lunar mission it may be better to make a new larger stage or lander using several of Helios's 15 klbf Deneb engines.

[deltaV]

From the video section:

https://twitter.com/bccarcounters/status/1750912993607459012

Very happy to announce that this week @NASASpaceflight live will feature Impulse Space CEO Tom Mueller (@lrocket).

The show will start on Sunday at 3 p.m. Eastern time.

Link:

This is starting in half an hour.

Edit: that live interview happened. The same YouTube link can be used to watch the replay.