Author Topic: ARCA  (Read 136931 times)

Offline Welsh Dragon

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Re: ARCA
« Reply #60 on: 09/21/2020 05:16 pm »
I have every faith they will make their balloon launched rocket supersonic seaplane launched rocket steam powered rocket* work.

*To be updated for next iteration.

Offline ncb1397

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Re: ARCA
« Reply #61 on: 09/21/2020 05:26 pm »

But people who think it's a waste also have a right to make that point.  Arca tries to get contributions from the general public, and it's a public service to get out the message that they're wasting money.

Are you talking about their Patreon page? Highest tier is $35, and they have 22 patrons, meaning the most they are bringing in is $770 a month. It is like donating to your local rocket club or something.

If all it does is create entertaining videos about setting up test stands and steam rockets (see wikipedia page linked below for background) that is actually something that a lot of money is spent on. The last Avengers movie cost almost half a billion dollars. Is all that money necessarily a waste? Objectively, it probably is and could be used for far more worthy causes, but such is the world we live in and is not necessarily unusual. Their 20,500 subscribers suggests they have an audience for whatever it is they are doing - even if that is just some decently produced videos on youtube.

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

Offline ChrisWilson68

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Re: ARCA
« Reply #62 on: 09/21/2020 05:37 pm »

But people who think it's a waste also have a right to make that point.  Arca tries to get contributions from the general public, and it's a public service to get out the message that they're wasting money.

Are you talking about their Patreon page? Highest tier is $35, and they have 22 patrons, meaning the most they are bringing in is $770 a month. It is like donating to your local rocket club or something.

If all it does is create entertaining videos about setting up test stands and steam rockets (see wikipedia page linked below for background) that is actually something that a lot of money is spent on. The last Avengers movie cost almost half a billion dollars. Is all that money necessarily a waste? Objectively, it probably is and could be used for far more worthy causes, but such is the world we live in and is not necessarily unusual. Their 20,500 subscribers suggests they have an audience for whatever it is they are doing - even if that is just some decently produced videos on youtube.

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

I'm defending the right of people to point out what's wrong with Arca.

And you bash me for that because the amounts are small.

No.  I reject your argument and stand by my defense of the right of people to complain about Arca.

Anyone giving any amount of money should have the right to be exposed to all opinions about what they're spending money on.  I reject trying to stop negative opinions because the amounts are small.

And the Patreon page is just one way that Arca gets money.

Offline Davidthefat

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Re: ARCA
« Reply #63 on: 09/21/2020 05:46 pm »
Anyone remember they were trying to sell stocks in their company to the public before they were kicked out of New Mexico and the States in general?

I think they are trying to get some kind of credibility to get government contracts, and they may be doing that through showcasing their paper mache rockets on Youtube.

I remember their COO or CTO while they were in New Mexico had a background in video production with zero in engineering of any sort.

At best they are an aspiring rocket company with people with overconfidence in their abilities doing what they can with the very limited resources faking it till they make it. At worst flat out scammers. I'd like to think the former, and personally I just think he wants to be Elon Musk and get popularity through the general audience. Especially given the fact they seem to publish every little accomplishment/action on Youtube with clickbait thumbnails (a cute kitten?)

Offline whitelancer64

Re: ARCA
« Reply #64 on: 09/21/2020 06:18 pm »

But people who think it's a waste also have a right to make that point.  Arca tries to get contributions from the general public, and it's a public service to get out the message that they're wasting money.

Are you talking about their Patreon page? Highest tier is $35, and they have 22 patrons, meaning the most they are bringing in is $770 a month. It is like donating to your local rocket club or something.

If all it does is create entertaining videos about setting up test stands and steam rockets (see wikipedia page linked below for background) that is actually something that a lot of money is spent on. The last Avengers movie cost almost half a billion dollars. Is all that money necessarily a waste? Objectively, it probably is and could be used for far more worthy causes, but such is the world we live in and is not necessarily unusual. Their 20,500 subscribers suggests they have an audience for whatever it is they are doing - even if that is just some decently produced videos on youtube.

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

I'm defending the right of people to point out what's wrong with Arca.

And you bash me for that because the amounts are small.

No.  I reject your argument and stand by my defense of the right of people to complain about Arca.

Anyone giving any amount of money should have the right to be exposed to all opinions about what they're spending money on.  I reject trying to stop negative opinions because the amounts are small.

And the Patreon page is just one way that Arca gets money.

He didn't say that you (or anyone else) couldn't point out things wrong with ARCA.

I don't see where he did any bashing, either.

I don't see how you think he's trying to stop anyone, negative opinions or not.
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
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Offline gongora

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Re: ARCA
« Reply #65 on: 09/21/2020 06:20 pm »
Every time we have an ARCA thread it devolves into a bunch of name calling and repetitive sniping until the thread ends up getting removed.  If you don't like ARCA, fine.  Say it once and move on.  Go read some other threads.  This repetitive griping is going to be deleted.

Offline ringsider

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Re: ARCA
« Reply #66 on: 09/21/2020 07:03 pm »
Every time we have an ARCA thread it devolves into a bunch of name calling and repetitive sniping until the thread ends up getting removed.  If you don't like ARCA, fine.  Say it once and move on.  Go read some other threads.  This repetitive griping is going to be deleted.
I can appreciate where you are coming from in terms of thread tidiness etc., but perhaps it's worth remembering that old Arca threads were deleted around the time of <edit> his legal troubles.

Perhaps newer audiences don't have the context of those interesting times, and some of this discussion has to be tolerated as they release new material?

Personally I find Arca entertaining and don't take them too seriously; they raise a little bit of money and they certainly spend it on making some interesting things, no matter how good or bad those things are. There are worse beasts in the jungle, as we have seen with other firms in the past.
« Last Edit: 09/22/2020 02:07 pm by ringsider »

Offline launchwatcher

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Re: ARCA
« Reply #67 on: 09/21/2020 07:22 pm »
Every time we have an ARCA thread it devolves into a bunch of name calling and repetitive sniping until the thread ends up getting removed.  If you don't like ARCA, fine.  Say it once and move on.  Go read some other threads.  This repetitive griping is going to be deleted.
I can appreciate where you are coming from in terms of thread tidiness etc., but perhaps it's worth remembering that old Arca threads were deleted around the time of the indictment - and let us not forget the guy defended himself, and was found to be innocent of the charges.
Please double-check your sources.   Popescu was neither indicted nor acquitted of the charges.   His case never reached the trial stage.   

A grand jury declined to indict him, and the prosecutor asked that charges be dismissed "without prejudice", which means that he could be charged again for the same acts should prosecutors uncover additional evidence against him.

https://www.lcsun-news.com/story/news/local/2018/05/16/criminal-charges-against-arca-ceo-dumitru-popescu-dropped/616598002/
« Last Edit: 09/21/2020 07:23 pm by launchwatcher »

Offline john smith 19

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Re: ARCA
« Reply #68 on: 09/21/2020 08:29 pm »
Being steam powered its not a fire risk if anything goes wrong.
To most inanimate objects probably not.

But human skin starts to scald (slowly) at 44c.

At 250c you're looking at 2nd degree burns and with enough steam they will cover your body.

It is dangerous but unlike (for example) hypergolic propellants it is not persistently dangerous.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline CameronD

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Re: ARCA
« Reply #69 on: 09/22/2020 01:10 am »
Personally I find Arca entertaining and don't take them too seriously; they raise a little bit of money and they certainly spend it on making some interesting things, no matter how good or bad those things are. There are worse beasts in the jungle, as we have seen with other firms in the past.

Well, given Arca's present pre-disposition towards over-sized bottle-rockets, climbing-helmets, psychologists, cute kittens and booze-ups, would it be wrong to suggest discussion be moved to 'Spaceflight Entertainment and Hobbies'?!??

Whatever it is they're doing, they certainly seem to be enjoying themselves! :)
« Last Edit: 09/22/2020 01:15 am by CameronD »
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline tyrred

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Re: ARCA
« Reply #70 on: 09/22/2020 08:47 am »
It's always buyer beware.

Offline zubenelgenubi

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Re: ARCA
« Reply #71 on: 09/22/2020 06:23 pm »
Every time we have an ARCA thread it devolves into a bunch of name calling and repetitive sniping until the thread ends up getting removed.  If you don't like ARCA, fine.  Say it once and move on.  Go read some other threads.  This repetitive griping is going to be deleted.
Moderator statement posted on September 21.
CW68 continues posting repetitive griping on September 22.
Post deleted.
« Last Edit: 09/22/2020 06:25 pm by zubenelgenubi »
Support your local planetarium! (COVID-panic and forward: Now more than ever.) My current avatar is saying "i wants to go uppies!" Yes, there are God-given rights. Do you wish to gainsay the Declaration of Independence?

Offline ncb1397

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Re: ARCA
« Reply #72 on: 09/23/2020 08:56 pm »
They are removing the old leaky water tank with a different design spherical tank (looks like much lower volume).

« Last Edit: 09/23/2020 08:57 pm by ncb1397 »

Offline ncb1397

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Re: ARCA
« Reply #73 on: 11/18/2020 12:07 am »
This was a fun watch...



The reaction should be fun...

"Ecorocket" specs:

mass: 4400 kg
payload: 10 kg
staging velocity: Mach 2.5
cost: $390,000


Offline Steven Pietrobon

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Re: ARCA
« Reply #74 on: 11/18/2020 05:53 am »
The video shows a LAS-25D engine test with the small round tank, which is new I believe. They have renamed their small launch vehicle from LAS-25D/HAAS to EcoRocket.

First stage uses technology that is "a very well guarded secret at ARCA" to boost Isp from 50 to 80 seconds. Perhaps they are adding in some hydrogen peroxide to the water to give it a bit more kick, along with carrying batteries to heat the water during flight (which they've mentioned before). Using stainless steel for the rocket would also allow higher temperatures. First stage lands back at the flat launch pad.

Second stage is kerosene and hydrogen peroxide (HTP) using a plug nozzle engine. Propellant mass is 480 kg (70 kg kerosene and 410 kg HTP). From the press conference, dry mass is 40 kg.

Will take off and land on its own legs as exhaust temperature is only 90 C. Schedule is

9 December 2020. Mission 9. Vertical takeoff and landing sequence for first stage.
1 March 2021. Complete ground tests for the second stage.
1 April 2021. Suborbital flight of second stage.
1 June 2021. First orbital launch attempt.
1 October 2021. First qualification flight for commercial services.

€1M development cost. $390K per launch or $39K/kg, which is still very expensive.
« Last Edit: 11/18/2020 06:09 am by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Steven Pietrobon

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Re: ARCA
« Reply #75 on: 11/18/2020 05:56 am »
EcoRocket Heavy payload is 60 t with reusable second stage! $1080M per flight or $18/kg! €30M development cost! Saying the ERH development has already started.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline TrevorMonty

Re: ARCA
« Reply #76 on: 11/18/2020 07:45 am »
They maybe onto something with steam powered booster. Steam is storing energy provided by powergrid which provides launch energy,  with batteries energy 7% needed for landing stage.While not particularly high performing it only needs to get 2nd stage high enough that atmospheric drag isn't issue.


Offline Steven Pietrobon

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Re: ARCA
« Reply #77 on: 11/18/2020 07:54 am »
They could make the first stage a bit smaller if they just used decomposed HTP. That seems to be a lot less complex, and gets higher Isp, about 117 seconds.

http://www.astronautix.com/h/h2o2.html
« Last Edit: 11/18/2020 07:56 am by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline trimeta

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Re: ARCA
« Reply #78 on: 11/18/2020 04:34 pm »
They maybe onto something with steam powered booster. Steam is storing energy provided by powergrid which provides launch energy,  with batteries energy 7% needed for landing stage.While not particularly high performing it only needs to get 2nd stage high enough that atmospheric drag isn't issue.
My understanding was that in two-stage-to-orbit rockets, the first stage contributes quite a lot of velocity to the second stage, not just altitude.

Offline Craftyatom

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Re: ARCA
« Reply #79 on: 11/18/2020 06:53 pm »
They maybe onto something with steam powered booster. Steam is storing energy provided by powergrid which provides launch energy,  with batteries energy 7% needed for landing stage.While not particularly high performing it only needs to get 2nd stage high enough that atmospheric drag isn't issue.
My understanding was that in two-stage-to-orbit rockets, the first stage contributes quite a lot of velocity to the second stage, not just altitude.
It does depend slightly on the launch vehicle.  For reusable concepts, a relatively low-powered first stage can be a good idea, since it makes recovery easier (since the first stage doesn't get as far downrange).  For rockets with low-thrust upper stages, however, the first stage has to do a lot of work to make sure the upper stage doesn't fall back into the atmosphere too quickly, and it's more efficient to thrust downrange in the process.

"Pop-up" first stages are feasible, but they depend on a number of trades.  For example, in this case, since the second stage has to provide the vast majority of delta-v, its payload mass fraction is atrocious.  A bigger second stage would help, but then you'd need a bigger first stage to lift it.  On the other hand, keeping the second stage small but using a bigger first stage would lead to a more traditional gravity turn trajectory, reducing gravity losses.

I must admit, I don't see the appeal.  First off, one of the clear advantages of a pop-up first stage is that the second stage shouldn't need to be designed for aero loading - and yet their second stage is right there in the airstream.  Just keep a big fairing attached to the first stage, and second stage mass will drop; keep in mind that 10kg less second stage dry mass would double payload capacity.  Second, switch to a large, conventional second-stage nozzle.  Even recent trades have suggested that an aerospike just isn't worth it for a vacuum engine, and with a large-diameter first stage fairing, they could use as big a nozzle as is mass-efficient.  Again, small gains are a big deal on this scale.

I know there have been warnings about not letting this devolve into an ARCA-bashing thread.  I do think there are some interesting concepts here, even if the way they're presented is... occasionally misleading.  But the way to get people to believe in you as a spaceflight company is not to announce a $39,000/kg reusable microlauncher scheduled for NET Q4 of next year, imo.  I like the clear delineation between current and future plans: it's good to have big, inspiring concepts on the horizon, while using smaller and simpler designs to get a foothold in the market.  But in this case I just don't think there's a very convincing call to action.

Of course, IANARS.  If they can get the secret sauce flowing and hit those lofty targets, more power to them.
All aboard the HSF hype train!  Choo Choo!

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