I understand that Stoke is developing a Methalox engine for its first stage. Why? They should just buy 2 or 3 raptors for each first stage and focus on designing the vehicle and the second stage. Let SpaceX work on the engines. Would be faster and way cheaper than developing your own full-flow methane engine. I guarantee that SpaceX would sell them the engines since they can manufacture them in high volume and Stoke does not compete with Starship. Plus Elon is all about full reuse and has always been about enabling space and not hiding tech. Additionally Stoke could run them at less thrust and make them last longer.
Quote from: Carlos Course 16 on 09/27/2023 05:00 pmI understand that Stoke is developing a Methalox engine for its first stage. Why? They should just buy 2 or 3 raptors for each first stage and focus on designing the vehicle and the second stage. Let SpaceX work on the engines. Would be faster and way cheaper than developing your own full-flow methane engine. I guarantee that SpaceX would sell them the engines since they can manufacture them in high volume and Stoke does not compete with Starship. Plus Elon is all about full reuse and has always been about enabling space and not hiding tech. Additionally Stoke could run them at less thrust and make them last longer.There's no indication that SpaceX is willing to sell Raptors to third parties. And even if they did, SpaceX wants to continuously iterate on Raptor's design, they're not going to write a contract that says "we will continue to deliver version X of Raptor even if we've moved on to much better versions internally." And no company would want a contract saying "we can change the product we're providing you without warning at any time."Now, the better question is whether Stoke should consider buying engines from someone like Ursa Major Technologies, which exclusively sells engines. Their Arroway is a 200,000 lbf methalox engine, not full-flow but fuel-rich staged combustion. There are advantages to full-flow, but I think for Stoke it would be worth it to buy a first-stage engine off the shelf. If Ursa Major offered appropriate prices and timelines, of course.
Plus they've already developed their own hydrolox engine in house. That's no small feat.Coming up with another engine won't be totally new to them.
Now, the better question is whether Stoke should consider buying engines from someone like Ursa Major Technologies, which exclusively sells engines. Their Arroway is a 200,000 lbf methalox engine, not full-flow but fuel-rich staged combustion. There are advantages to full-flow, but I think for Stoke it would be worth it to buy a first-stage engine off the shelf. If Ursa Major offered appropriate prices and timelines, of course.
RLV is about 2mt with US recovered, which would put booster thrust around 300mt so 3 Arroways. Which requires high throttle range from landing engine.
https://twitter.com/jeff_foust/status/1710038335840977404QuoteStoke Space announced it has raised a $100M Series B round. More importantly, it's named its rocket: Nova.
Stoke Space announced it has raised a $100M Series B round. More importantly, it's named its rocket: Nova.
1. https://arstechnica.com/space/2023/09/stoke-space-hops-its-upper-stage-leaping-toward-a-fully-reusable-rocket/ claims Stoke can lift "up to 7 metric tons to low-Earth orbit". https://en.wikipedia.org/wiki/Comparison_of_orbital_launch_systems claims Stoke can do 1500 kg to LEO but doesn't cite anything for that. Do we have any other sources on the payload mass capability of their rocket or other parameters such as rocket dimensions or thrust that we could estimate payload from? [Edit: Robotbeat claims "3mT reusable" four posts ago, which seems consistent with the 7 tonnes if the latter is expendable.]2. https://www.stokespace.com/stoke-space-series-b/ claims Stoke has $175M of funding so far. That's in between the development cost of expendable Falcon 1 (~$100M) and the original expendable Falcon 9 (~$300M) and their rocket is in between those two in payload capacity too. So Stoke's funding is about what I'd expect it to cost to develop an expendable. It seems unlikely that Stoke will develop a fully reusable rocket for that amount of money, so they either need to get profit from launching an expendable version or they need more funding.
1. https://arstechnica.com/space/2023/09/stoke-space-hops-its-upper-stage-leaping-toward-a-fully-reusable-rocket/ claims Stoke can lift "up to 7 metric tons to low-Earth orbit". https://en.wikipedia.org/wiki/Comparison_of_orbital_launch_systems claims Stoke can do 1500 kg to LEO but doesn't cite anything for that. Do we have any other sources on the payload mass capability of their rocket or other parameters such as rocket dimensions or thrust that we could estimate payload from? [Edit: Robotbeat claims "3mT reusable" four posts ago, which seems consistent with the 7 tonnes if the latter is expendable.]
Quote from: deltaV on 10/06/2023 01:56 am1. https://arstechnica.com/space/2023/09/stoke-space-hops-its-upper-stage-leaping-toward-a-fully-reusable-rocket/ claims Stoke can lift "up to 7 metric tons to low-Earth orbit". https://en.wikipedia.org/wiki/Comparison_of_orbital_launch_systems claims Stoke can do 1500 kg to LEO but doesn't cite anything for that. Do we have any other sources on the payload mass capability of their rocket or other parameters such as rocket dimensions or thrust that we could estimate payload from? [Edit: Robotbeat claims "3mT reusable" four posts ago, which seems consistent with the 7 tonnes if the latter is expendable.]https://www.cnbc.com/2023/10/05/reusable-rocket-startup-stoke-space-raises-100-million.html says it's "5,000 kilograms to low Earth orbit" (unclear if reusable or expandable). I guess either they keep changing their minds about its capacity or different employees are using different ground rules (e.g. altitude, inclination, reserves)?
2. https://www.stokespace.com/stoke-space-series-b/ claims Stoke has $175M of funding so far. That's in between the development cost of expendable Falcon 1 (~$100M) and the original expendable Falcon 9 (~$300M) and their rocket is in between those two in payload capacity too. So Stoke's funding is about what I'd expect it to cost to develop an expendable. It seems unlikely that Stoke will develop a fully reusable rocket for that amount of money, so they either need to get profit from launching an expendable version or they need more funding.
Quote from: deltaV on 10/06/2023 01:56 am2. https://www.stokespace.com/stoke-space-series-b/ claims Stoke has $175M of funding so far. That's in between the development cost of expendable Falcon 1 (~$100M) and the original expendable Falcon 9 (~$300M) and their rocket is in between those two in payload capacity too. So Stoke's funding is about what I'd expect it to cost to develop an expendable. It seems unlikely that Stoke will develop a fully reusable rocket for that amount of money, so they either need to get profit from launching an expendable version or they need more funding.I largely agree. I do think we should acknowledge, however, that SpaceX was developing in a very different market and time than Stoke is. There's a lot of lessons that SpaceX had to pay for that Stoke gets for free from the modern industry's collective knowledge. Both technical (stainless steel in non-"balloon" tanks is worth consideration) and organizational (how small of a team can launch an orbital rocket?). Not to mention having access to modern manufacturing techniques (modern 3D printing for example). There's lots of ways it could be substantially cheaper to develop an LV today than in the 00s.
3mT fully reusable, 5mT with first stage reuse but upper stage expended, and 7mT fully expendable.