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匪夷所思!為什麼馬斯克造出的火箭是白菜價?猛禽量產秘密乾貨

2021-08-07由 天外飛艦 發表于 歷史

【中英對照翻譯】星港之旅每日宇航員對伊隆·馬斯克的採訪第1期

匪夷所思!為什麼馬斯克造出的火箭是白菜價?猛禽量產秘密乾貨

Starbase Tour and Interview with Elon Musk

Interview Part 1

On July 30, 2021 Tim Dodd received a tour of Starbase with SpaceX CEO, CTO, and founder Elon Musk。 This article includes key takeaways from the first 50 minutes of the over 2 hour long interview。

訪談第一部分

2021年7月30日,蒂姆·多德接受了SpaceX執行長、首席技術官和創始人伊隆·馬斯克對Starbase參觀邀請。本文包括長達2個多小時的採訪中——前50分鐘的主要收穫。(

總共分3期

Manufacturing:

Musk once again emphasized that manufacturing is underrated and design is overrated; developing a production system is 10-100 times harder than designing the product, which according to Musk is especially true with Raptor。 As volume production increases the amount of effort that goes into design rounds down to 0。

For an example, Musk stated that designing a closed cycle engine is easy, but the extremely hard part is the cost per tonne of thrust under $1,000。 With each Raptor producing 230 tonnes of thrust this means that each engine must cost less than $230,000 to produce。 Musk continued stating that the cost per tonne to orbit and the cost per tonne to the surface of Mars is several orders of magnitude too high on current launch vehicles。 This is why it is so important to move as much mass and complexity as possible to the ground。

製造方面:

馬斯克再次強調,製造被低估,而設計被高估了;

開發一個量產系統比設計產品難10-100倍

。根據馬斯克的說法,這在猛禽上尤其如此。隨著批次生產的增加,用於設計的工作量就會降為0。

舉個例子,馬斯克表示,設計一個封閉式迴圈發動機很容易,但極難的部分是

每噸推力的成本低於1000美元

由於每臺猛禽能產生

230噸

的推力,這意味著每臺發動機的生產成本必須

低於23萬美元

馬斯克繼續說,在目前的運載火箭上,每噸到軌道的成本和每噸到火星表面的成本都高了好幾個數量級。

這就是為什麼將盡可能多的質量和複雜性轉移到地面是如此重要。

(這裡的to the ground應該是指火星表面)

Super Heavy Design:

Musk noted that Super Heavy’s dry mass should be under 200 tonnes, although the dry mass is a moving target。 The engines, including mounting mass, are 2 tonnes; the fuel tank and the liquid oxygen (LOx) tanks are roughly 80 tonnes; and the interstage is around 20 tonnes, including four grid fins that each weigh roughly 3 tonnes。 Musk noted that he expects to be able to cut the mass of each grid fin in half。 He further noted that currently everything is too heavy, including avionics, grid fins, and batteries。 The grid fins are currently electrically powered, using a modified Tesla Model 3 motor to drive them。 In continuation of using Tesla parts, the batteries are currently energy optimized instead of power optimized, as a car needs several hours of energy, whereas the grid fins only need two or three minutes of power。 Due to these reasons, Musk noted, like much of Starship’s design, the batteries are temporary, and battery mass can drop by a factor of ~10。

超重助推器的設計:

馬斯克指出,超重助推器的幹質量應該在

200噸以下

,儘管幹質量是一個變動目標。

每臺發動機,包括安裝裝置質量,為2噸(29臺重

58噸

);燃料箱和液氧(LOX)箱大約為

80噸

;中間級大約為

20噸

,包括四個網格鰭,每個大約為3噸(4個

12噸

)。

馬斯克指出,他期望能夠將每個

網格鰭的質量減少一半

他進一步指出,目前所有東西都太重了,包括航空電子裝置、網格鰭和電池。

目前,

網格鰭是電力驅動

的,使用改進的特斯拉

Model 3電機

來驅動它們。

在繼續使用特斯拉部件的同時,電池目前是

能量最佳化

的,而不是功率最佳化的,因為一輛汽車需要幾個小時的能量,而網格鰭只需要兩三分鐘的能量。

由於這些原因,馬斯克指出,與Starship的大部分設計一樣,電池是臨時的,

電池質量可以下降~10倍

The booster is designed to carry 3,600 tonnes of propellant, of which ~78% of that is liquid oxygen。 The Raptor burns at a mixture ratio of 3。5 to 3。7, which is fuel rich to burn cooler than the stoichiometric ratio, which would melt the engine。 Super Heavy’s propellant residuals (the amount of fuel that cannot be used without risking damage to the vehicle) are on the order of 20 tonnes, Musk notes, which is significantly higher than the 1 tonne propellant residual of the Falcon 9。 With optimizations to design Musk noted that the final dry mass of Super Heavy should be between 160 and 200 tonnes。

推進器被設計為可攜帶

3600噸推進劑

,其中約

78%是液氧

猛禽燃燒的混合比為

3。5至3。7

,這是

富燃料燃燒(100%消耗甲烷)

,以比化學計量比更冷,以防融化發動機。

馬斯克指出,超重助推器的推進劑殘餘量(在不損害飛行器的情況下不能使用的燃料量)在

20噸左右

,這比獵鷹9號的

1噸

推進劑殘餘量要高得多。

隨著對設計的最佳化,超重助推器的最終幹質量應該在

160至200噸

之間。

An interesting note is the grid fins on Super Heavy do not fold in like on the Falcon 9, as they are another mechanism, which adds unnecessary complexity, mass, and failure modes。 Additionally, the increase in drag from the grid fins being deployed during ascent is small, assuming they are not at a high angle of attack。

一個有趣的現象是,超重助推器上的網格鰭並不像獵鷹9號那樣摺疊起來,因為它們是另一種機制,

為了不增加不必要的複雜性、質量和故障模式

此外,在上升過程中,假設

網格鰭不處於高攻角

,那麼

網格鰭展開(旋轉)後增加的阻力也很小

匪夷所思!為什麼馬斯克造出的火箭是白菜價?猛禽量產秘密乾貨

Musk’s Engineering Philosophy:

Musk overviewed his five step engineering process, which must be completed in order:

馬斯克的工程哲學:

馬斯克概述了他的五步工程流程,這些流程必須按順序完成:

Make the requirements less dumb。 The requirements are definitely dumb; it does not matter who gave them to you。 He notes that it’s particularly dangerous if someone who is smart gives them the requirements, as one may not question the requirements enough。 “Everyone’s wrong。 No matter who you are, everyone is wrong some of the time。” He further notes that “all designs are wrong, it’s just a matter of how wrong。”讓這些要求不那麼愚蠢。這些要求肯定是愚蠢的;誰給你的並不重要。他指出,

如果是聰明人給他們的要求,那就特別危險,因為人們可能對要求的質疑不夠。

“每個人都是錯的。不管你是誰,每個人在某些時候都是錯的”。他進一步指出,

“所有的設計都是錯的,只是錯的程度不同而已”

。(UP總結:防止權威過於影響判斷,從而不讓任何人喪失思考能力,以防變成只會執行命令的機器)

Try very hard to delete the part or process。 If parts are not being added back into the design at least 10% of the time, not enough parts are being deleted。 Musk noted that the bias tends to be very strongly toward “let’s add this part or process step in case we need it。” Additionally, each required part and process must come from a name, not a department, as a department cannot be asked why a requirement exists, but a person can。非常努力地去

刪除零件或過程

。如果至少有

10%的時間

沒有把零件加回設計中,那麼就說明被刪除的零件不夠多。馬斯克說,顯而易見的偏見是:我們非常強烈地傾向於 “讓我們新增這個部分或流程步驟,以備我們需要”。此外,每個所需的零件和流程必須來自於一個名字,而不是一個部門,

因為不能問一個部門為什麼存在一個需求,但一個人可以

Simplify and optimize the design。 This is step three as the most common error of a smart engineer is to optimize something that should not exist。簡化和最佳化設計。這是第三步,因為聰明的工程師最常見的

錯誤是最佳化不應該存在的東西

Accelerate cycle time。 Musk states “you’re moving too slowly, go faster! But don’t go faster until you’ve worked on the other three things first。”加快

週期時間

。馬斯克指出,“你的動作太慢了,要快一點!但在你先做完其他三件事之前,不要快。”(UP猜測這句話的意思是:完成三個週期之前,速度可以慢,但之後加快)

Automate。 An important part of this is to remove in-process testing after the problems have been diagnosed; if a product is reaching the end of a production line with a high acceptance rate, there is no need for in-process testing。

實現自動化

。其中一個重要的部分是在問題被診斷出來後,取消過程中的測試;如果一個產品在到達生產線的末端時有很高的接受率,就沒有必要進行過程中的測試。

Additionally, Musk restated that he believes everyone should be a chief engineer。 Engineers need to understand the system at a high level to understand when they are making a bad optimization。 As an example, Musk noted that an order of magnitude more time has been spent reducing engine mass than reducing residual propellant, despite both being equally as important。

此外,馬斯克重申,他認為

每個人都應該成為首席工程師

工程師們需要在高層次上理解系統,以瞭解他們何時在進行錯誤的最佳化

作為一個例子,馬斯克指出,減少發動機質量比減少殘餘推進劑多花了一個數量級的時間,儘管兩者同樣重要。

匪夷所思!為什麼馬斯克造出的火箭是白菜價?猛禽量產秘密乾貨

Raptor 2:

Musk noted that SpaceX has made parts of version 2 of Raptor, called Raptor 2, including the thrust chamber assembly。 Teams have finished the design of the turbo pumps, and are expecting to be ready to fire the first Raptor 2 by the end of August。 Raptor 2 will reach 230 tonnes of thrust at 298 bar main combustion chamber pressure, with Musk commenting “come on… we have to get 2 more bar out of that thing!” Raptor 2 features a larger throat, which decreases the area ratio; this causes a decrease in specific impulse of around 3 seconds, but increases thrust significantly。 Despite having a lower ISP, this allows for booster engines to be more efficient as it decreases gravity loses。

第二代猛禽:

馬斯克說,SpaceX已經制作了第二版猛禽的部件,稱為猛禽2號,包括推力室元件。

團隊已經完成了渦輪泵的設計,並預計在8月底前準備好發射第一個猛禽2號。

猛禽2號將在

298bar

的主燃燒室壓力下達到230噸的推力,馬斯克評論說:“來吧……我們必須從那東西中再得到2巴!”

猛禽2號的特點是

喉部較大,降低了面積比

;這導致

比衝下降約3s

,但

推力明顯增加

儘管有一個較低的ISP,但這使得助推器引擎的效率更高,因為它

減少了重力損失

It was also stated that SpaceX will move volume production of Raptor to McGregor, but keep the Hawthorne factory for development engines and Raptor Vacuum versions。

還有人說,SpaceX將把猛禽的量產產線轉移到麥格雷戈,但保留霍桑工廠用於開發發動機和猛禽真空版。

匪夷所思!為什麼馬斯克造出的火箭是白菜價?猛禽量產秘密乾貨

麥格雷戈

Starship Separation System and Attitude Control:

Following Musk’s five step plan, SpaceX has decided to remove the pushing separation system from Starship and will instead rely on conservation of angular momentum to separate the stages。 Right before main engine cutoff (MECO), Super Heavy will gimbal its engines, causing the vehicle to start rotating。 The latches between Starship and Super Heavy will then release, causing the vehicles to float apart; the whole process is similar to how SpaceX deploys the Starlink satellites。 This serves two purposes, as it separates the stages while starting the booster’s flip, which it needs to conduct for the boost back burn。

星艦分離系統和姿態控制:

按照馬斯克的五步計劃,SpaceX已經決定從星艦上

取消推動杆分離系統

,而是依靠

角動量守恆來分離各級

就在主引擎關閉(MECO)之前,超重將使其引擎保持平衡,飛行器開始旋轉——然後,“星艦 ”和 “超重 ”之間的鎖釦將被釋放,即

飛行器浮動分離

整個過程類似於SpaceX部署 “星鏈 ”衛星的方式。這有兩個目的,因為它在

啟動助推器翻轉時將各級(卡扣)分開

,而助推器需要進行

回燃

In addition to this, SpaceX has decided to remove the dedicated hot gas thrusters from Super Heavy。 To replace it, SpaceX will use the ullage gas from the tanks for attitude control by having four vents spaced 90° apart。 By venting the tanks through these vents, they will be able to control the attitude of the booster during the flip。 This has the advantage of using the ullage gas, which would need to be vented either way, to do useful work to the vehicle。

除此以外,SpaceX還決定從超重上

拆除專用熱氣推進器

取而代之的是

透過相隔90°的四個通風口

利用油箱中的加壓廢氣進行姿態控制

透過這些通風口排放油箱的加壓廢氣,將能夠在翻轉期間控制助推器的姿態。

這樣做的好處是,

利用無論哪種方式都需要排放的艙底廢氣對飛行器進行有用姿態控制工作

HLS:

Once again following Musk’s five step process, Musk outlined that he is optimistic that HLS will not need the landing thrusters at the top of the lunar Starship。 If SpaceX is able to demonstrate that landing on the moon with Raptor will not create too large of a hole in the lunar regolith, they may remove the thrusters from the lunar Starship。 While the exact Raptor configuration for lunar Starship has not been decided, it is likely that it’ll be the same as the Earth variant with three sea-level Raptors and three vacuum Raptors。

人類著陸系統(月球):

馬斯克再次遵循五步程式,概述了他對

HLS將不需要月球艦的著陸推進器(腰部)

的樂觀看法。

如果SpaceX能夠

證明用猛禽登陸月球不會在月球碎石上造成太大的洞

,他們可能會從月球星艦上移走(腰部)推進器。

雖然月球艦的確切猛禽配置尚未決定,但很可能與地球上的變體相同,有

三個海平面猛禽和三個真空猛禽

文章英文原版:https://everydayastronaut。com/starbase-tour-and-interview-with-elon-musk

本文許可CC BY-NC-SA 4。0協議(creativecommons。org/licenses/by-nc-sa/4。0/deed。zh)

翻譯:天外飛艦,原文作者:Everyday Astronaut,原文標題Starbase Tour and Interview with Elon Musk

因已同步轉載英文原版,故翻譯已適當新增UP主本地化解讀,以使方便理解。

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