Talk:SpaceX Raptor

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On 31 December 2019, it was proposed that this article be moved from Raptor (rocket engine family) to SpaceX Raptor. The result of the discussion was moved.

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Reason of reduction of cavitation risk.

Specific impulse is increased, and the risk of cavitation at inputs to the turbopumps is reduced due to the higher propellant fuel mass flow rate per unit of power generated.[30]

It looks to me that the risk of cavitation reduction increase is incorrect or at least not sourced properly. Going to the cited source, it does not say anything like that. The actual reason is because the actual cause of cavitation is when local pressure is lower than the vapor pressure. Lower temperature reduces the vapor pressure. — Preceding unsigned comment added by 69.181.215.242 (talk) 19:23, 14 October 2021 (UTC)[reply]

Image of outdated design?

I believe the image used in the article is of an older design iteration. May need to update. — Preceding unsigned comment added by Enzo32ferrari (talk • contribs) 17:17, 3 November 2021 (UTC)[reply]

@Enzo32ferrari: Well, copyright is the main reason that adding newer Raptor images is not allowed, as the images must be licensed to be able to be commercialized, adapted, and share freely. This is the best that we can find. You can try to find a better image as well! (You might want to read this first: c:Commons:Licensing) CactiStaccingCrane (talk) 10:46, 15 December 2021 (UTC)[reply]

incorrect specific impulse listed

Currently the specific impulse is listed as 330s for sea level and 380s for vacuum, which is wrong. 380s is only achievable with a vacuum adapted version of the engine, requiring a larger expansion nozzle and hence not suitable for use at sea level. The best number I can find for the sea level engine in vacuum is 363s. The article should make the distinction between a sea level unit in vacuum and a vacuum optimized unit, as doing otherwise is inaccurate and misleading. ArbitraryConstant (talk) 18:01, 27 December 2021 (UTC)[reply]

mass flow rate does not align with other values

The mass flow rate is correct given the information in the footnote - at 2.23 MN of thrust and ISP of 330 - but it's listed with the other items in the box and that gives the impression that they align. And they do not - at an ISP of 330 and a thrust of 1.81 MN, the mass flow rate is 559 kg/s, since MFR = thrust in newtons / exhaust velocity, and exhaust velocity = ISP * 9.81 — Preceding unsigned comment added by 67.160.53.158 (talk) 16:59, 26 January 2022 (UTC)[reply]

Raptor 2 needs a photo

Raptor 2 was publically unveiled a few hours ago in Texas at the Elon Musk "update" on Starship. It looks VERY DIFFERENT (much slimmer) than the Raptor 1 that was previously disclosed.

Many people should have been able to take photographs of it; hopefully one of them will upload to Wikimedia.N2e (talk) 06:10, 11 February 2022 (UTC)[reply]

We can only hope... The free license culture is not strong on the Boca Chica community. CactiStaccingCrane (talk) 03:04, 31 March 2022 (UTC)[reply]

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Raptor 3

Elon musk just announced Raptor 3, wich has more thrust and chamber pressure, can someone write it in? Fehér Zsigmond (talk) 07:43, 14 May 2023 (UTC)[reply]

Hello? They literally just conducted a test, can someone please answer me? Fehér Zsigmond (talk) 19:22, 15 May 2023 (UTC)[reply]

Someone has put in the thrust and chamber pressure data in the article and infobox, however especially for the infobox it should be noted that this was just a test and we don't know what the qualification pressure and thrust are planned to be. All engines need headroom over the qualification power, so operational specifications may be lower. I don't know how this is usually handled here, so I'm not going to change anything, just something to be aware of for any editors who do. 37.4.235.39 (talk) 19:17, 23 May 2023 (UTC)[reply]

According to SpaceX, the #s for Raptor 3 SL are:

Thrust: 280tf

Specific impulse: 350s (In Vacuum)

Engine mass: 1525kg

Engine + vehicle-side commodities and hardware mass : 1720kg (This is WP:OR, but this is likely the start COPVs) Redacted II (talk) 17:54, 3 August 2024 (UTC)[reply]

It's not stated if thrust is at SL or vacuum. Vacuum is the specmanship number, but takeoff (SL) thrust is the number everyone cares about because it sets takeoff acceleration. The two are in the same 330/350 ratio as the Isp (since that's the entire reason for the change; the mass flow rate is unchanged). So it could be 264/280 tf, or 280/297 tf. 97.102.205.224 (talk) 14:20, 5 August 2024 (UTC)[reply]

It is likely SL, as a R3 prototype hit 269 tf on a test stand.

NOTE: EVERYTHING BELOW THIS LINE IS WP:OR.

There is another indication that these are SL #s.

According to https://www.spacex.com/vehicles/starship/, RVac gets 258 tf, and RSL gets 230.

Assuming both engines have the same mass flow, then we can calculate RSL ISP. This is assuming the RVAC has an ISP of ~370.

370/258*230=329.84496. This matches R2SL expected ISP very well. Redacted II (talk) 15:24, 5 August 2024 (UTC)[reply]

Assuming both engines have the same mass flow Aye, there's the rub. It's common to decrease the throat diameter in vacuum engines to increase the area ratio more than enlarging the bell can achieve alone. Which, for a fixed chamber pressure, implies a lower mass flow. Early raptors kept the throat area and mass flow rate the same, but one of the annoying things about this subject is the number and frequency of changes. 97.102.205.224 (talk) 13:29, 6 August 2024 (UTC)[reply]

There is no source stating that thrust is in vacuum, nor is there a source (or any indication, for that matter) saying that they diverged the throat diameter in the vacuum engines. Redacted II (talk) 16:54, 6 August 2024 (UTC)[reply]