Author Topic: Blue Origin : BE-3 and BE-3U Engine  (Read 125563 times)

JCRM

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Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #160 on: 02/20/2024 09:23 am »
I'm a Canadian. I speak English. I speak French. I am also bilingual when it comes to measurements, both imperial and metric. I could live with thrust in kilogram thrust force. But what the hell is a newton?

How much force does a kilogram exert on the moon?
Trick question.  Is there someone there to watch it?
In space no one can watch you stream

Steven Pietrobon

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Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #161 on: 02/22/2024 05:10 am »
How much force does a kilogram exert on the moon?

F = m*a = 1*1.625 = 1.625 N.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

DanClemmensen

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Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #162 on: 02/22/2024 05:24 am »
How much force does a kilogram exert on the moon?

F = m*a = 1*1.625 = 1.625 N.
Actually, that's just the gravitational force, and it's only true if the kilograms is at rest on the lunar surface. That same kilogram will exert less gravitational force on the Moon if it's further away. (inverse square law). On the other hand, if that kilogram hits the Moon at high velocity, it will briefly exert quite a bit more force during the collision. For example, if it's a kilogram of exhaust from a BE-3 landing on the Moon, it might exert 488 KN, very very briefly.

JCRM

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Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #163 on: 02/22/2024 01:29 pm »
How much force does a kilogram exert on the moon?

F = m*a = 1*1.625 = 1.625 N.
In terms of kilogram force? (that being the context it was asked in)

baldusi

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Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #164 on: 02/27/2024 02:19 am »
I'm a Canadian. I speak English. I speak French. I am also bilingual when it comes to measurements, both imperial and metric. I could live with thrust in kilogram thrust force. But what the hell is a newton?
It's basically 1kgf * 9.8 (the gravity force at Earth surface). Why? Because using kgf/tonne force (which is what Russians and Elon Musk actually use for first stage) let's you easily calculate the R/W ration in the Earth. But when you don't have to fight against gravity, each Newton will accelerate 1kg of mass at 1m/s. So for any orbital maneuver calculation, that's actually the unit you need. To repeat: for calculating the T/W for a first stage engine, the natural unit of mass-force is used (either kgf or lbf). But for orbital mechanics, you use Newtons or lbf. But lbf impart a pound of mass an acceleration of 32.174 049 ft/s2. So the Newton is much cleaner.

edzieba

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Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #165 on: 02/27/2024 04:45 pm »
I'm a Canadian. I speak English. I speak French. I am also bilingual when it comes to measurements, both imperial and metric. I could live with thrust in kilogram thrust force. But what the hell is a newton?
It's basically 1kgf * 9.8 (the gravity force at Earth surface). Why? Because using kgf/tonne force (which is what Russians and Elon Musk actually use for first stage) let's you easily calculate the R/W ration in the Earth. But when you don't have to fight against gravity, each Newton will accelerate 1kg of mass at 1m/s. So for any orbital maneuver calculation, that's actually the unit you need. To repeat: for calculating the T/W for a first stage engine, the natural unit of mass-force is used (either kgf or lbf). But for orbital mechanics, you use Newtons or lbf. But lbf impart a pound of mass an acceleration of 32.174 049 ft/s2. So the Newton is much cleaner.
Or, rather than performing an arbitrary unit-change partway through your ascent calculations, you can use the correct unit for force the entire time (Newtons) and calculate TWR using it when useful - since TWR is a unitless ratio you will get there whether you use Newtons or 'Kilograms force'. All you are doing by making up a 'kilogram force' unit is shoving a factor of 0.98 around to a different part of your equations to overcomplicate things.
At least Newtons do not vary depending on local gravity or altitude!

Steven Pietrobon

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Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #166 on: 03/03/2024 03:24 am »
Or, rather than performing an arbitrary unit-change partway through your ascent calculations, you can use the correct unit for force the entire time (Newtons) and calculate TWR using it when useful - since TWR is a unitless ratio you will get there whether you use Newtons or 'Kilograms force'. All you are doing by making up a 'kilogram force' unit is shoving a factor of 0.98 around to a different part of your equations to overcomplicate things.
At least Newtons do not vary depending on local gravity or altitude!

A minor nit-pick, bit it is newton without a capital N!

https://math.ucr.edu/home/baez/physics/General/SI_units.html

Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

clongton

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Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #167 on: 03/03/2024 05:41 pm »
A minor nit-pick, bit it is newton without a capital N!

Steve, you're such a purist! We might be twins
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

MP99

Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #168 on: 03/03/2024 06:33 pm »
Or, rather than performing an arbitrary unit-change partway through your ascent calculations, you can use the correct unit for force the entire time (Newtons) and calculate TWR using it when useful - since TWR is a unitless ratio you will get there whether you use Newtons or 'Kilograms force'. All you are doing by making up a 'kilogram force' unit is shoving a factor of 0.98 around to a different part of your equations to overcomplicate things.
At least Newtons do not vary depending on local gravity or altitude!

A minor nit-pick, bit it is newton without a capital N!

https://math.ucr.edu/home/baez/physics/General/SI_units.html

Yeah, I'm not blinkin-well (Bowlderised) gonna do that.

1 Newton is agreed. Proper noun, so capitalised.

If there are 3x people called "Martin" in the room, then there are "three Martins". If my father, my mother & myself are in the same room then there are three "Smiths". Every person I know would crucify me if I wrote "three smiths" (that is very clearly 3x people who smith as a profession (EG blacksmith) rather than 3x people called "Smith").

Quite frankly, I think your reference is (massively Bowlderised) er, "wrong".

Even if proper nouns have weird rules for capitalisation, this is the capitalisation of a *UNIT* *DERIVED* from a name.

Newton is *ALWAYS* *ABBREVIATED* as capital "N" so that it is disambiguated from "nano". IE 7nN is unambiguously "seven nano-Newtons". Has anyone ever written "seven nano newtons" as "7nn" without being ridiculed?? Have you ever seen that in a scientific paper?

Is 7nm "7 newton metres" or "7 nano metres"?

Cheers, 1x Martin

Sent from my 21091116UG using Tapatalk

Redclaws

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Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #169 on: 03/03/2024 06:48 pm »
Or, rather than performing an arbitrary unit-change partway through your ascent calculations, you can use the correct unit for force the entire time (Newtons) and calculate TWR using it when useful - since TWR is a unitless ratio you will get there whether you use Newtons or 'Kilograms force'. All you are doing by making up a 'kilogram force' unit is shoving a factor of 0.98 around to a different part of your equations to overcomplicate things.
At least Newtons do not vary depending on local gravity or altitude!

A minor nit-pick, bit it is newton without a capital N!

https://math.ucr.edu/home/baez/physics/General/SI_units.html

Yeah, I'm not blinkin-well (Bowlderised) gonna do that.

1 Newton is agreed. Proper noun, so capitalised.

If there are 3x people called "Martin" in the room, then there are "three Martins". If my father, my mother & myself are in the same room then there are three "Smiths". Every person I know would crucify me if I wrote "three smiths" (that is very clearly 3x people who smith as a profession (EG blacksmith) rather than 3x people called "Smith").

Quite frankly, I think your reference is (massively Bowlderised) er, "wrong".

Even if proper nouns have weird rules for capitalisation, this is the capitalisation of a *UNIT* *DERIVED* from a name.

Newton is *ALWAYS* *ABBREVIATED* as capital "N" so that it is disambiguated from "nano". IE 7nN is unambiguously "seven nano-Newtons". Has anyone ever written "seven nano newtons" as "7nn" without being ridiculed?? Have you ever seen that in a scientific paper?

Is 7nm "7 newton metres" or "7 nano metres"?

Cheers, 1x Martin

Sent from my 21091116UG using Tapatalk

You are of course welcome to your perspective, but newton the unit is emphatically *not* a proper noun.  No more so than joule or watt or kelvin or ampere.  Do you think we should capitalize all of those too?  They’re also units named after people, which use capital letters for the unit abbreviation.  But unless you think it’s correct to write that you have a “400 Watt power supply”, then… yeah.  As a matter of standard usage, you’re just wrong.  Sometime what feels correct … isn’t.  Insisting on why it feels correct to you explains it - yeah, it does feel a little odd writing lower case newton but not watt, because Newton is more commonly seen as a name than unit and Watt is not  - but it doesn’t change what the standard usage is.

JEF_300

Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #170 on: 03/04/2024 02:33 am »
Life was perfectly fine until someone thought that a Newton was a better way of expressing rocket thrust than pounds. I can assure you, that 99.9% of the general public (including me) has no idea what rocket thrust in newtons means. Newtons may be fine in a rocket lab or for rocket scientists, but please, for the sake of the 99.9%, banish the irritating newton.

And most of the general public has a useful conception of 10,000 pounds of force? I think the forces we're dealing with here are large enough that they're never really going to be understandable outside of math anyway, so you might as well go with the unit that makes the math easier.

EDIT: It's possible that this is less true when you start wading into in-space thrusters. Most of the time I've been doing engine math, it's for booster engines.
« Last Edit: 03/04/2024 02:39 am by JEF_300 »
Wait, ∆V? This site will accept the ∆ symbol? How many times have I written out the word "delta" for no reason?

meekGee

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Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #171 on: 03/04/2024 12:06 pm »
A lbf is about 5 N, I don't see how anyone can have "no idea" what a million lbf is in N, unless they just don't want to. (Hint: about 5 MN. Also, if you want to divide by 5, divide by 10 and multiply by 2 - close enough!)

Also, meters get to lowercase since they're not named after people and are common words.  Other SI units are capitalized, always. Joules and Watts and Kelvins.

Some people find pounds somehow more "intuitive", but if you ever want to calculate anything - energy and delta-V, momentum and impulse, etc - metric is objectively better, because imperial has to use conversation factors even within itself and metric doesn't.
« Last Edit: 03/04/2024 12:08 pm by meekGee »
ABCD - Always Be Counting Down

Yellowstone10

Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #172 on: 03/04/2024 12:28 pm »
Also, meters get to lowercase since they're not named after people and are common words.  Other SI units are capitalized, always. Joules and Watts and Kelvins.

That's incorrect, at least in English:

Quote
Unit names
According to the SI Brochure, unit names should be treated as common nouns of the context language. This means that they should be typeset in the same character set as other common nouns (e.g. Latin alphabet in English, Cyrillic script in Russian, etc.), following the usual grammatical and orthographical rules of the context language. For example, in English and French, even when the unit is named after a person and its symbol begins with a capital letter, the unit name in running text should start with a lowercase letter (e.g., newton, hertz, pascal) and is capitalised only at the beginning of a sentence and in headings and publication titles.

https://en.wikipedia.org/wiki/International_System_of_Units

meekGee

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Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #173 on: 03/04/2024 12:55 pm »
Also, meters get to lowercase since they're not named after people and are common words.  Other SI units are capitalized, always. Joules and Watts and Kelvins.

That's incorrect, at least in English:

Quote
Unit names
According to the SI Brochure, unit names should be treated as common nouns of the context language. This means that they should be typeset in the same character set as other common nouns (e.g. Latin alphabet in English, Cyrillic script in Russian, etc.), following the usual grammatical and orthographical rules of the context language. For example, in English and French, even when the unit is named after a person and its symbol begins with a capital letter, the unit name in running text should start with a lowercase letter (e.g., newton, hertz, pascal) and is capitalised only at the beginning of a sentence and in headings and publication titles.

https://en.wikipedia.org/wiki/International_System_of_Units
So the rule I quoted was not just how I see it used, but how it was explicitly taught in school.  Watts and Teslas and whatnot.

I can't explain the discrepancy.  Do you keep the same rule when abbreviating the units too?  Or only for full-form names?

I only remember meters and seconds as getting a break.  Shrug.

Everything else though about lbf vs N still stands though...

EDIT: yeah it appears the shortened units are capitalized (except for m and s), and the full-form ones aren't.  Somehow that distinction got lost either on me or on my teacher.

But common usage varies. I have seen kWatt-hr and kWh used interchangeably for example.
« Last Edit: 03/04/2024 05:10 pm by meekGee »
ABCD - Always Be Counting Down

MP99

Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #174 on: 03/04/2024 01:17 pm »
Or, rather than performing an arbitrary unit-change partway through your ascent calculations, you can use the correct unit for force the entire time (Newtons) and calculate TWR using it when useful - since TWR is a unitless ratio you will get there whether you use Newtons or 'Kilograms force'. All you are doing by making up a 'kilogram force' unit is shoving a factor of 0.98 around to a different part of your equations to overcomplicate things.
At least Newtons do not vary depending on local gravity or altitude!

A minor nit-pick, bit it is newton without a capital N!

https://math.ucr.edu/home/baez/physics/General/SI_units.html

Yeah, I'm not blinkin-well (Bowlderised) gonna do that.

1 Newton is agreed. Proper noun, so capitalised.

If there are 3x people called "Martin" in the room, then there are "three Martins". If my father, my mother &amp; myself are in the same room then there are three "Smiths". Every person I know would crucify me if I wrote "three smiths" (that is very clearly 3x people who smith as a profession (EG blacksmith) rather than 3x people called "Smith").

Quite frankly, I think your reference is (massively Bowlderised) er, "wrong".

Even if proper nouns have weird rules for capitalisation, this is the capitalisation of a *UNIT* *DERIVED* from a name.

Newton is *ALWAYS* *ABBREVIATED* as capital "N" so that it is disambiguated from "nano". IE 7nN is unambiguously "seven nano-Newtons". Has anyone ever written "seven nano newtons" as "7nn" without being ridiculed?? Have you ever seen that in a scientific paper?

Is 7nm "7 newton metres" or "7 nano metres"?

Cheers, 1x Martin

Sent from my 21091116UG using Tapatalk

You are of course welcome to your perspective, but newton the unit is emphatically *not* a proper noun.  No more so than joule or watt or kelvin or ampere.  Do you think we should capitalize all of those too?  They’re also units named after people, which use capital letters for the unit abbreviation.  But unless you think it’s correct to write that you have a “400 Watt power supply”, then… yeah.  As a matter of standard usage, you’re just wrong.  Sometime what feels correct … isn’t.  Insisting on why it feels correct to you explains it - yeah, it does feel a little odd writing lower case newton but not watt, because Newton is more commonly seen as a name than unit and Watt is not  - but it doesn’t change what the standard usage is.
Hmm, it appears I was right about the capitalisation of the unit abbreviations, but had incorrectly believed that was also the standard for writing out unit names in longhand.

My apologies.

Cheers, Martin

Sent from my 21091116UG using Tapatalk

Craigles

Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #175 on: 03/04/2024 07:02 pm »
Do we have a good estimate about the ISP of at least the BE-3? I see the BE-3 specs in Jeff Faust's article from 2015-04-07, http://spacenews.com/blue-origin-completes-be-3-engine-as-be-4-work-continues/ .

Back to the present based on 2024-02-21 photographs showing the size of the New Glenn second stage pathfinder tanks and published payload expectations, can we approximately surmise the required flight profile and thence the required thrust for the BE-3U? It would help to clarify what we know about the current BE-3U's cycle; is it an expander cycle or a bleed off cycle?

Maybe to estimate the NG second stage flight profile we need to consider the New Glenn and the Vulcan (as announced/built) discussion in other threads, but the New Glenn intertwines with the BE-3U. I appreciate that this is an in-depth question.

Edit: I see that sdsds and Robert_the_Doll were discussing this on 2015-02-15 before a 43-post discussion about the metric system.
« Last Edit: 03/04/2024 07:15 pm by Craigles »
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deltaV

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Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #176 on: 03/04/2024 09:50 pm »
It would help to clarify what we know about the current BE-3U's cycle; is it an expander cycle or a bleed off cycle?

BE-3U is an expander bleed cycle, a.k.a. open expander cycle. BE-3PM is a combustion tap-off cycle. See https://en.wikipedia.org/wiki/BE-3#Engine_design.

whitelancer64

Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #177 on: 03/04/2024 11:04 pm »
To the best of my knowledge, Blue Origin has never publicly released the ISP numbers for either the BE-3 or the BE-3U or the BE-4. There have been a number of estimates made both on this forum and elsewhere over the past few years. The best we have is that Tory Bruno has said that BE-4 performance numbers have been better than expected, but he could not give out specifics.
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Starshipdown

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Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #178 on: 03/06/2024 05:28 pm »
Part of the tradeoffs that BE-3U makes for the relatively high thrust it has is that it probably has a somewhat lower ISP, than say, the classic RL-10 family. I would suspect that it's around 400 seconds. The RS-25/SSMEs achieved both, but at a great cost in terms of development time with its staged combustion cycle, and then early in operation with regards to maintenance. The BE-3U being an open expander cycle engine probably won't be too much higher than 400 seconds, if at all.

deltaV

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Re: Blue Origin : BE-3 and BE-3U Engine
« Reply #179 on: 03/06/2024 06:39 pm »
The BE-3U being an open expander cycle engine probably won't be too much higher than 400 seconds, if at all.

LE-5B is another open expander upper stage engine and its specific impulse is 447 seconds (https://en.wikipedia.org/wiki/LE-5). I'd guess that BE-3U will probably have roughly that specific impulse as well (within +/- 10 seconds or so). What's the basis of your 400 second estimate?

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