Mass Produced Multi-Engine, Multi-Stage Rocket

[MSimon]

Can you still edit your original post?

I dunno. If the edit button is there I'd say so.

I know as "moderator" I can edit anything anytime.

[djolds1]

I was just trying to make the concept simple.
Anyhow, as far as space launch is concerned, the equation "More useless weight to lift = more cost per ton in LEO" holds pretty much true.

And the point I've been trying to make is no it doesn't. That is "true" only because NASA & the other major government space agencies have pursued hardware paths that have made it "true." NASA & Co. have semi-consciously confused efficiency and cost.

Pressure fed design do have some limitations on flow rate, which means that they cannot achieve the same high thrust as turbo-pumps. I am sure that material and technological advancements will smooth some or all of these limitations, but for now Turbo-pumps are difficult to beat.

When dealing with throw away machines, performance is a fungible. What matters is cash cost to LEO, not mass ratio to LEO.

It might be of interest for you that the second stage engine of SPACEX Falcon1 is a pressure-fed Engine:
http://spacex.com/falcon1.php

Consider the Beal BA-2.

[Aero]

Yes, my original post has an edit button. But the thread is now displaying the text, so edit to what benefit?

[MSimon]

Yes, my original post has an edit button. But the thread is now displaying the text, so edit to what benefit?

You want to correct an error?

[Skipjack]

Absent nuclear power of some sort, or breakthrough physics, ELVs are the way to go.

I dont agree, and many others do not agree either. I do think that we will see one or the other breakthrough soon that will be enabling.
Polywell is one potential candidate.

[Giorgio]

I was just trying to make the concept simple.
Anyhow, as far as space launch is concerned, the equation "More useless weight to lift = more cost per ton in LEO" holds pretty much true.

And the point I've been trying to make is no it doesn't. That is "true" only because NASA & the other major government space agencies have pursued hardware paths that have made it "true." NASA & Co. have semi-consciously confused efficiency and cost.

Pressure fed design do have some limitations on flow rate, which means that they cannot achieve the same high thrust as turbo-pumps. I am sure that material and technological advancements will smooth some or all of these limitations, but for now Turbo-pumps are difficult to beat.

When dealing with throw away machines, performance is a fungible. What matters is cash cost to LEO, not mass ratio to LEO.

Of course cost is the main factor, and my point was exactly that.
More weight to lift is not only referred exclusively to the fuel weight, but also to the weight of the extra metal that has to be manufactured (at a cost) and the weight of all the extra equipment needed to handle the increased complexity of keeping stable a rocket composed by more than 650 rockets that are necessary to bring 10 tons to LEO with OTRAG system!


I "doubt" that all of these costs summed can be lower than the cost of the turbopump system that is used in the Falcon9 and that can launch 10 tons at LEO (rated for 10-20 launches).
A complete cost analysis should be performed to check this point, but I think that no one here has all the info necessary to make it.

It might be of interest for you that the second stage engine of SPACEX Falcon1 is a pressure-fed Engine:
http://spacex.com/falcon1.php

Consider the Beal BA-2.

The only test made was 20 seconds long and not much can be said on it becouse (for what are my info) no pubblic data is available....

[Aero]

Yes, my original post has an edit button. But the thread is now displaying the text, so edit to what benefit?

You want to correct an error?

Do you know what the error is or was? I don't. I did edit the original post a moment ago, and pasted the two links in as code for all to see. But as the text of the post is now being displayed it looks to me like the blank page display was a transient that has either corrected itself or been corrected. As for the funny behavior of the url tags - well, I don't understand it but I won't worry much until it bites me again.

[djolds1]

Of course cost is the main factor, and my point was exactly that.
More weight to lift is not only referred exclusively to the fuel weight, but also to the weight of the extra metal that has to be manufactured (at a cost)

Marginal cost versus the costs of ever more finely machined and crafted turbomachinery and pricey lightweight materials like lithium-aluminum for tankage. Steel tankage, kerosene, LOX and nitrogen pressurant are cheap next to the bleeding edge toys, even in bulk.

and the weight of all the extra equipment needed to handle the increased complexity of keeping stable a rocket composed by more than 650 rockets that are necessary to bring 10 tons to LEO with OTRAG system!

I think I understand our problem here. You're still talking about OTRAG in particular, while I thought the conversation had migrated to LCLV in general.

See again this:
http://www.dunnspace.com/
And especially this:
http://www.dunnspace.com/leo-1-10.pdf

[Giorgio]

Yes, my reference was to OTRAG system.

It's a big PDF, I will try to read it during the weekend.

[MSimon]

Yes, my original post has an edit button. But the thread is now displaying the text, so edit to what benefit?

You want to correct an error?

Do you know what the error is or was? I don't. I did edit the original post a moment ago, and pasted the two links in as code for all to see. But as the text of the post is now being displayed it looks to me like the blank page display was a transient that has either corrected itself or been corrected. As for the funny behavior of the url tags - well, I don't understand it but I won't worry much until it bites me again.

I exercised my moderator privileges and fixed it yesterday. I don't know why it didn't work but adding spaces around the urls fixed it.

This board does some strange things from time to time.

[Aero]

I exercised my moderator privileges and fixed it yesterday. I don't know why it didn't work but adding spaces around the urls fixed it.

Well thanks for that. I was getting a little nervous at the time.