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Check of HLLVs because of (severe) doubts

Posted by: Ekkehard Augustin - Sun Jan 07, 2007 11:25 am
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Check of HLLVs because of (severe) doubts 
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Post Check of HLLVs because of (severe) doubts   Posted on: Sun Jan 07, 2007 11:25 am
The question if HLLVs are "cheaper than light lifters requires some looks into the degree to which their capacities are exploited and exhausted.

Like I said already elsewhere I up to now only know of degrees that mean that they are NOT used up to a degree at which they are advantegous.

It is required to look into the ratios between payloads and capacities. The $ per payload-weight aren't a technological numbers but should be checked also in another thread.

Because I am going to apply a list of rockets/vehicles I will do some ckecks here.



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Post    Posted on: Tue Jan 23, 2007 12:02 pm
I up to now checked the following rockets

    Delta IV Heavy
    Delta 3
    Atlas V


These I selected because there were launches of dummies and satellites - but I do NOT have a look on rockets never launched. I also don't include here launches of interplanetary spacecrafts because for these three no interplanetary capacities are isted under www.astronautix.com .

For these three I concentrate on data under www.astronautix.com but will look for other sources also.

The check has just begun but of these three Delta 3 has the most limited capacities but these three have carried similar/comparable weights - and it turns out that Delta 3 as the lightest was cheapest although the ratio between payload and capacity was NOT the best one.

There are ratios above 86% - so I am doubting if safety margins play any role.

So at present my severe doubts are confirmed a bit by the data available by experience but this might change yet as I apply more data - I have to check much more rockets, missions. launches.

This also underlines what Richard Speck has said and stated recently in the Centenial Challenges section.

Since this is the Technology section I am looking on the ratio between propellant and payload in particular - Delta 3 has the best ratio of the three and consumes the smallest amount of propellant per kg payload.



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Post    Posted on: Tue Jan 23, 2007 1:05 pm
Ekkehard Augustin wrote:
I also don't include here launches of interplanetary spacecrafts because for these three no interplanetary capacities are isted under www.astronautix.com .


I thought NASA used Atlas V to launch their New Horizons probe to Pluto.

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Post    Posted on: Tue Jan 23, 2007 1:19 pm
Hello, Andy Hill,

you are right. That's listed under www.astronautix.com as well as the launch of MRO via the Atlas V - but under www.astronautix.com I didn't find up to what's the maximum weight of interplanetary spacecrafts the Atlas V can launch - only the maximum weight to LEO and the maximum weight to GEO is listed.

Because of this no ratios between the weight of MRO and New Horizons on the one hand and the maximum interplanetary weight the Atlas V can launch to its interplanetary destination on the other hand are possible.

This needs to be looked for in other sources.



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Post    Posted on: Fri Feb 02, 2007 6:32 pm
Atlas V cannot even launch 20 tons to LEO as Titan IV could. Lockheed has no Titan IV/Delta IV/Proton/Ariane 5 equivalent at the moment.

Angara will exceed Titan IV in lofting capability.


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Post    Posted on: Sat Feb 03, 2007 9:46 am
In between I calculated Ariane and Proton using the numbers of www.astronautix.com.

Again Delta 3 as the rocket with the smallest payload capacity of them all turns out to need fewr propellant per kg of payload than all the othgers considered here up to now.

Ariane and Proton have other capabilities yet that I will involve into my checks later - but these capabilities don't have to do that much with payload weight but with flexibility and scope of purposes or services merely.

I also had a look to Saturn V - and again it turns out that the propellant required per kg of payload is higher than in the case of the Delta 3.

At present I keep this all limited to rockets and vehicles that really and actually have been launched with real or dummy payloads - but because it has been mentioned that often already I looked for the data about Sea Dragon under www.astronautix.com.. - and didn't find the amount of propellant listed there.

For this reason it seems to be impossible to include Sea Dragon here at present - it will be possible later at looks to other numbers or using other sources.

The costs in dollars will be considered in the Financial Barriers section in the future but by a short calculation it urned pout that splitting the capacity into 4,500 to 5,500 times the capacity of Launchpoint Technologies' maglev and doing that number of launches would be significantly cheaper. Please don't argue here by what WannabeSpaceCadet answered to me in the maglev-thread because he was misunderstanding me completely - it is possible to organize and coordinate operations in orbit with each other as well as with launches so that it is economical to catch the payloads from their different orbits.

But mI will keep out of consideration maglev here because the technology is different to that of rockets.



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Post    Posted on: Mon Feb 05, 2007 11:00 pm
Ekkehard,

comparing launch vehicle performance is not so straightforward. Taking an extreme example, the Saturn I-21 that launched Skylab had a theoretical maximum payload of 116t for 2700t launch mass to 185km, a ratio of about 4%. That's very good even for a three-stage vehicle.

Delta-3 could launch about 8.3t to the same orbit for 301t liftoff mass - still a very good performance, specially given that it was a 2.5 stage design. Few rockets have done better. On the other hand, PL fraction to GTO is typically better for full three-stagers (or 3.5-stagers).

However, in terms of cost, it matters how many stages and how many engines a rocket has. That was one of the driving factors behind the Ariane 5 design. It reduced the number of liquid engines from 10 on Ariane 44L to 2 - at the cost of a much worse PL/mass ratio (which was also influenced by other factors, but let's not get into too much detail).

So you will need at least some sort of weighting factors to derive any useful cost prediction from Payload capability and total mass alone. You need to factor in the complexity.

I tend to agree in one point, though: Bigger is not automatically cheaper. I've said it before, if you just scale one up linearly you have a rocket that grows with the cube of the scale factor but the thrust only grows with the square; and then we haven't even talked about bending moments yet. Right size for the application is the key.

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Post    Posted on: Tue Feb 06, 2007 7:46 am
Hello, May Lange,

what you are mentioning of course is well known to me and I am completely aware of it.

The weights of the hardware and weigting factors will or at least might be considered later - I am just at the beginning and want to avoid too long posts (which I missed in the Lunar Soyuz-thread in the Financial Barriers section because it is required to keep the links and connections between aspects and details).

I also want to keep the possibility that everyone interested in constructive and positive participation really can participate.

To focus on the ratio between propellant and payload at present also has to do with the circumstance that weight, engines etc. could be made or kept reusable like in the case of the Space Shuttle and concepts lke those of SpaceX, RpK, Scaled Composites/MAV and t/Space.

Another essential point is that I want to enable and actively initiate returns back to the formerly higher level of conversation I experienced during 2004.



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Post    Posted on: Tue Feb 06, 2007 8:31 pm
In this case your best approach is probably to stay with narrowly defined (and often used) reference missions, e.g. GTO and 185km...200km circular or something similar. That would be an interesting exercise indeed. As a second step, several types within a family would be interesting to see the effect of such things as additional boosters. However, I seem to recall that such an analysis was published a few years ago by a US university (I agree that's not very precise, but maybe it rings a bell with you?) and they came to the interesting conclusion that for current commercial payloads, the most successful launcher actually had near the highest published launch cost. It was apparently factors like access to data and availability that drove the market.

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Post    Posted on: Wed Feb 07, 2007 9:20 am
Hello, Max Lange,

sorry for the typing error. :)

may be I am doing something similar to what you are mentioning. I use an Excel file into which payload weights, rocket capacities etc. are to be inserted, ratios are calculated and so on.

This enables first raw findings and will lead to closer, broader and more precise inquiries as time goes by.

Families will be considered in the comparisons-thread merely - this thread is meant to do a more general investigation having a different structur which is indicated a bit by the distinction between rockets having flown really and others that haven't flown yet.

Will be interesting it seems.



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EDIT: Just a few moments ago I recognized that I misunderstood the term "families" here. I understood that term as I am using it in the comparisons-thread but suppose now that the term is menat to consider the Proton-rockets one Family, the Delta-rockets another family and so on. This family-view I have in mind to consider here nonetheless to improve precision and insight.


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Post    Posted on: Mon Feb 19, 2007 12:26 pm
There is a particular reason why I am starting with ratios between propellants and payloads neglecting the weight of the stages of the rocket(s).

If there weren't the payload the rocket wouldn'tbe launched - meaning that the application of its technology wouldn't be required.

In so far the payload is causing the consumption of propellant and the energy the propellant is the source of.

What I have severe doubts of is that heavy lift would be cheaper than light lift, that it would consume less propellant per kg of payload than light lift...

A later look onto the hardware will be a more detailed look into it.



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Post    Posted on: Tue Feb 20, 2007 4:25 pm
There is an additinal reason to neglect the weight of the hardware - some rockets use strap-on boosters which add some weight that would be saved if the other stages would be larger. The weight that would be saved is the weight of the additional hulls and tanks of the boosters. The majority of the propellant inside the boosters would be required even if the other stages would be larger.

This means that the check wouldn't start simple but it would be complex from the beginning - because besides the hardware weight the reason of that weight would have to be considered also. One such reason may be the strap-on boosters. ...



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Post    Posted on: Thu Mar 01, 2007 2:55 pm
Andy Hill wrote:

I thought NASA used Atlas V to launch their New Horizons probe to Pluto.


It was a strange view, a giant pluto payload sitting on a little rocket


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Post    Posted on: Thu Mar 01, 2007 4:38 pm
Lunar-Humans wrote:
It was a strange view, a giant pluto payload sitting on a little rocket
You mean this view?
Image
Actually, the fairing was much larger than the space craft, as you can see from this view:
Image
And that is only the top half of the fairing, as you can see in theses views:
ImageImage
So in reality it was a tiny payload on a pretty big rocket.

More and larger pictures are on the web here:
http://mediaarchive.ksc.nasa.gov/search.cfm?cat=137


Last edited by campbelp2002 on Thu Mar 01, 2007 4:54 pm, edited 1 time in total.



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Post    Posted on: Thu Mar 01, 2007 4:52 pm
campbelp2002 wrote:
So in reality it was a tiny payload on a pretty big rocket.


No change there then. :)

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