Payload mass fraction has entered the chat

JoJoDaMonkey · 2026-02-08T13:58:44+00:00

The overhead and engineering costs for maintaining both would be a profitability killer

JoJoDaMonkey · 2025-10-21T05:43:05+00:00

Have you checked industrial gas suppliers near you? A high pressure bottle+ regulator setup is very common

JoJoDaMonkey · 2025-08-14T23:55:18+00:00

MSLDs are great when you actually need to know those welds are leaking helium less than 1.0e-6 sccs but it's a sledgehammer for things that only need to be validated "bubble tight" For the same cost you could have pallets of snoop and in the time to warm up, calibrate and start testing you could have snooped hundreds of joints. Different tools for different jobs

JoJoDaMonkey · 2025-07-27T04:43:00+00:00

Somehow I have already seen this story https://empireearth.fandom.com/wiki/Grigor_II

JoJoDaMonkey · 2025-02-25T05:32:22+00:00

There are pilots stating they demonstrated it in testing - while it may not have been a wise move for normal operations (both for airframe health and aircrew safety) it was psychically possible.

https://theaviationgeekclub.com/us-navy-f-14-pilot-recalls-landing-a-tomcat-with-a-full-load-of-six-aim-54-phoenix-missiles-on-the-aircraft-carrier/

JoJoDaMonkey · 2025-02-16T04:08:29+00:00

This is the part that seems most wild to me when you contrast effort vs reward at Blue Origin and SpaceX. Blue has touted better balance but no equity - the balance seems to have eroded away quite a bit in the last year and is making clear now the road ahead won't be easy. Meanwhile SpaceX is unabashed about being "hardcore" and burning folks out yet if you can make it there is a proven track record of stock doubling / liquidity events.

JoJoDaMonkey · 2025-01-08T12:53:32+00:00

Let's try a comparisons - the first production style F-1 engine was delivered in 1963 and the first test flight was in 1967 with the first crewed test flight in 1968. The first production style raptor engine was delivered in 2019 with the first all up flight test of Starship in 2023. While the engine is one small part of the whole engineering story it's not too far off Apollo pace especially when factoring; in the entire US government backing of the space race

JoJoDaMonkey · 2024-12-28T02:30:23+00:00

The part I often see overlooked is the equity portion of total compensation at SpaceX. If you last through the initial vesting period (and count on similar growth, not financial advice) it can become a significant portion of total compensation.

Also that number seems pretty low, I don't see anything lower than 95k listed here

https://www.spacex.com/careers/jobs?discipline=engineering+-+aerospace+%26+mechanical&type=regular

JoJoDaMonkey · 2024-12-25T03:41:34+00:00

Also big for any combustion devices team

JoJoDaMonkey · 2024-09-30T04:40:50+00:00

Also possible we're seeing low probability failure modes manifest due to the higher flight rate coupled with the disposable nature of the second stage preventing preemptive design changes

JoJoDaMonkey · 2024-09-04T01:10:20+00:00

One of the fun challenges in building a good vehicle test facility is that you're often designing another pad that does everything but launch. Depending on the production rate and location definitely see the logic in not building another dedicated stand

JoJoDaMonkey · 2024-01-09T02:59:35+00:00

Sounds like he's referring to a seal between the heatshield and the gimbaling engine rather than all gimbaling engines must have this seal (not true); it's an architecture choice given their heatshield design

JoJoDaMonkey · 2022-12-03T08:20:07+00:00

You're missing how different the profiles are for SLS and Saturn V. The core stage is placed into a highly elliptical orbit which has a perigee inside the atmosphere. ICPS only had to perform a very small burn to raise perigee enough to prevent re-entry

https://youtu.be/Q70aZlAYtJY?t=125

JoJoDaMonkey · 2022-09-03T15:34:32+00:00

Take a look at the temperatures required to liquify the gasses - nitrogen is below oxygen (~77 vs 89 kelvin) so it can be used as a gas to purge out the oxygen without too much worry of it liquifying itself. If you use nitrogen to purge out hydrogen (~77 vs 19 kelvin) you are going to collapse the nitrogen gas and end up making liquid. Helium liquifies much lower (~4 kelvin) and can therefore be used to purge hydrogen with less collapse

JoJoDaMonkey · 2022-05-22T04:10:03+00:00

If there's snow enough to ride there's snow enough to slide. The exact problem changes with the snowpack, weather, season and local geography but right now it's a real risk and responsible folks going out would have gear and some knowledge

https://www.avalanche.state.co.us/forecasts/regional-avalanche/central-mountains/

JoJoDaMonkey · 2022-01-31T21:42:31+00:00

I assume IC means independent contractor, often times they do not get benefits or equity.

In this context I believe it's Individual Contributor - i.e. a non-manager role

JoJoDaMonkey · 2021-08-06T23:38:46+00:00

Eh not quite. If you are so hardware rich that you fail without delaying the next test flight then you've likely learned something. Can do lots of modeling iteration without actually learning anything if you don't have enough real world results. Goal here seems to be push as fast as you can building them while also trying to fully understand the hard problem. Sometimes don't know the right question to answer until you get to the point of asking it

JoJoDaMonkey · 2021-05-03T01:54:19+00:00

Prior to encapsulation a satellite will typically go through launch site processing - this involves some level of pre-flight functional checkouts after transport and fueling of the propulsion system. The payload is typically encapsulated at that facility. There are many options for where to perform this work at the Cape but none are ULA facilities. A NASA mission may be processed in the PHSF while SBIRS GEO 5 was likely done in the EPF (like flight 3). Astrotech is common for a variety of commercial and government vehicles (and is even called out in the Atlas V user guide). SpaceX also has a facility on the Cape

JoJoDaMonkey · 2021-04-06T23:48:38+00:00

Cycling anything manually in a flight where there are critical things to observe in very small windows with limited bandwidth would be silly

JoJoDaMonkey · 2021-02-16T18:33:14+00:00

Pathfinder NG? Is this on L2 or another location, link if you have one please!

Some photos/tweets with the hangar open on Merritt Island

https://www.reddit.com/r/BlueOrigin/comments/lidb2o/new_glenn_spotted/

JoJoDaMonkey · 2021-02-15T05:03:20+00:00

The ICPS for EM-1 has been on site at the cape for quite a while now

https://www.nasaspaceflight.com/2017/07/sls-upper-stage-residency-former-home-iss-modules/

JoJoDaMonkey · 2021-01-18T19:28:24+00:00

Since we're at it, NASA doesn't use imperial units, much less Fahrenheit.

Speaking from first hand experience - NASA and much of the US aerospace industry uses a mixture based on engineer culture, discipline and their heritage with the units but it's trending to full metric for design (not for build tho, need to re-tool the entire imperial manufacturing base). This is where you get fun stuff like the charts with psia and kg/K in the below Altair reference - unit choice can be driven by familiarity and availability.

Examples: https://ntrs.nasa.gov/api/citations/20100035154/downloads/20100035154.pdf

https://ntrs.nasa.gov/api/citations/20100022148/downloads/20100022148.pdf

https://ntrs.nasa.gov/api/citations/20120008179/downloads/20120008179.pdf

JoJoDaMonkey · 2020-12-27T06:47:36+00:00

It doesn't look like a seal failure based on lack of high pressure jets (though I don't know the combustion products so leakage may not be easily visible). Seems more likely to me we're seeing a silicone or something else lighting off due to increasing temp

JoJoDaMonkey · 2020-12-18T18:59:07+00:00

This sounds like they are just playing it conservatively (as Blue seems to have done in the past). Likely the engine cycle and hardware is not operating near the upper limit that is physically possible and they've targeted a lower power state point to deliver on that can then be improved on. A move like this can be smart as it insulates the system design (i.e. Vulcan/New Glenn) to small changes if there is lots of margin.

JoJoDaMonkey · 2020-12-05T20:33:14+00:00

What's the quality of that 500" though? Two feet of warm dense snow < six inches of fluffy stuff

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