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How simple can a manned craft be?

Posted by: Andy Hill - Mon Feb 18, 2008 10:39 pm
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How simple can a manned craft be? 
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Post    Posted on: Wed Mar 05, 2008 7:12 pm
"But the engineers aren't stupid. If you could design a [insert name of product which requires regular or extensive maintenance] so much better then it currently is, you are making yourself obsolete. "

Actually, this is a perfect description of a stupid engineer. If I don't design a better product, somebody else will. When that better product is available, then my company loses business, and I'm out of a job. And if my boss finds out that I'm trying to make a bad design - look out - I'm fired. Same at NASA, same at ESA.

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Post    Posted on: Thu Mar 06, 2008 11:28 am
Hello, rpspeck,

I am not that sure regarding the loss(es) in the case that the orbiter requires less than $ 500,000 investment because it depends on the costs of deorbiting the orbiter. These costs will be the costs of the propellant consumed and - in the case under consideration - the investment costs of the expendable stage(s). It seems that a propellant weight of 100,000 kg LOX/cerosene costs $ 65,000 - so this alone wouldnt lead to a loss or a disadvantage.

The other aspect I was arguing under is that an expendable orbiter would have to be added to the variable costs of a flight while those variable costs would be smaller if the orbiter is reusable and mustnt be added to the variable costs.

It will be interesting to do a break-even-point-analysis in the Financial Barriers section - but at present I dont consider it to be worth the "pain".

The orbiters - regardless of meaning that Shuttles, capsules or the like - cost millions at present - except for your vehicle and the vehicles of Armadillo Aerospace. So its looking a bit as if the different orbiters have to be grouped into families.



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Post    Posted on: Thu Mar 06, 2008 3:30 pm
2.71 wrote:
"But the engineers aren't stupid. If you could design a [insert name of product which requires regular or extensive maintenance] so much better then it currently is, you are making yourself obsolete. "

Actually, this is a perfect description of a stupid engineer. If I don't design a better product, somebody else will. When that better product is available, then my company loses business, and I'm out of a job. And if my boss finds out that I'm trying to make a bad design - look out - I'm fired. Same at NASA, same at ESA.

2.71


Yes, that's exactly why NASA has built the ultimate money-spending rocket ever built.

Besides, i don't explain it very good. I had to ad another line to the last line. 'If you can buy something thats 5 steps ahead of what currently is on the market, you're only going to sell whats 1 or maybe 2 steps ahead'.

And NASA is the best example for that. Actually, talk to any bussinesman out there, it's nuts to put something in the market which is way better then anything else. You only have to make something that much better for a good price so people will buy it. If the competition comes along, you can built and market the next step.


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Post    Posted on: Thu Mar 06, 2008 7:17 pm
"1. But the engineers aren't stupid. If you could design a [insert name of product which requires regular or extensive maintenance] so much better then it currently is, you are making yourself obsolete.

2. Yes, that's exactly why NASA has built the ultimate money-spending rocket ever built.
Besides, i don't explain it very good. I had to ad another line to the last line. 'If you can buy something thats 5 steps ahead of what currently is on the market, you're only going to sell whats 1 or maybe 2 steps ahead'.
And NASA is the best example for that. Actually, talk to any businessman out there, it's nuts to put something in the market which is way better then anything else. You only have to make something that much better for a good price so people will buy it. If the competition comes along, you can built and market the next step."

I don't understand the point. So are you now saying that NASA is NOT trying to make bad designs? Now the NASA designs are TOO GOOD?

#1 implies that you think NASA engineers are colluding to make inferior designs. #2 says the opposite, that the designs are too good.

Being a businessman and engineer, I have to say that I am always looking for the next "killer application", or superior product.

Take for example, the iPod. Apple took advantage of technological development and jumped 2 or 3 steps ahead of existing MP3 players. The design of this product has allowed Apple to completely dominate a market that they previously had not entered. I don't think many businessmen would have said "No. let's make the first iPod 2GB. 10GB is too much of an improvement. And let's make it a little harder to use, too."

But we digress. My point was merely that safety and reliability are not the same as simplicity. NASA, LockMart, ESA, SpaceX, and Burt Rutan all have designs that are NOT maximally simple. This is because maximally simple is simply not good design.


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Post    Posted on: Thu Mar 06, 2008 11:14 pm
Ekkehard Augustin wrote:
Hello, rpspeck,

The orbiters - regardless of meaning that Shuttles, capsules or the like - cost millions at present - except for your vehicle and the vehicles of Armadillo Aerospace. So its looking a bit as if the different orbiters have to be grouped into families.

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I understand that current “Manned Spacecraftâ€


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Post    Posted on: Fri Mar 07, 2008 9:42 am
rpspeck wrote:
I am assuming that this thread is looking for a LOW COST vehicle (assuming that simplicity relates to cost as well as safety). Others have pointed out that there is no single answer in terms of safety: complexity (with redundant critical systems) can improve safety, or (with unnecessary complexity) can reduce it.


This is all true, I just felt that it must be possible to create a craft that didn't take years to manufacture everytime one was produced. I am not against complexity except where it causes manufacturing delays, cost increases, weight increase or unnecessary systems duplication.

rpspeck wrote:
I am certain that the initiator of the thread was not interested in how heavy and expensive one can make a spacecraft without improving safety: that exercise seems to have been done.


Exactly right, I was interested in discussing the construction of a simple light weight craft that could be produced cheaply and relatively quickly using as much off the shelf technology as possible. A lighter craft would obviously use a smaller booster bringing its launch cost down. While reusability is ultimately desireable I think using current technology would result in extra weight offsetting any launch savings made (I must admit to having no real knowledge of the trade offs involved in this assumption which is why I was interested in talking about it).

To clarify a light weight vehicle massing a couple of tons (max) able to carry 4-6 people on a short trip to LEO and dock with an orbiting facility. It would have to stay in orbit for a couple weeks then make the return trip with the crew. Reusability is optional based upon weight increase and required refurbishment after each flight.

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Post    Posted on: Fri Mar 07, 2008 11:41 am
Well, I do have nearly no problems with what you said, rpspeck, or with what you said, Andy.

I simply cannot agree that it would be uneconomical to launch a reusable orbiter by expendable stages. Losses or profits depend on the amount of revenues in comparison to the amount of costs which include the investment only as depreciations.

I have no problems with refurbishment costs if the flight rate is at a level where refurbishment costs plus the other costs are less that the the sum of the investments into all the expendable orbiters applied instead of reusable ones plus the other costs.

Andy, what about the CXV and the Dragon under the aspects you posted?



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Post    Posted on: Fri Mar 07, 2008 1:39 pm
Ekkehard Augustin wrote:
Andy, what about the CXV and the Dragon under the aspects you posted?


I think that these are closer than Orion to what I had in mind but they could still be made lighter (not sure how much weight could be attributed to excess NASA requirements). I would send cargo separately and make the craft smaller. I personally would trade a bit of space and comfort for a cheaper ticket. Make the time spent in the craft as short as possible and allow more space on the orbital facility to move around in.

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Post    Posted on: Tue Mar 11, 2008 7:39 pm
Andy Hill wrote:
I personally would trade a bit of space and comfort for a cheaper ticket. Make the time spent in the craft as short as possible and allow more space on the orbital facility to move around in.


If you want to talk about spaceflight a well paid engineer might be able to raise the money to pay for, then you must talk about a “Rationalâ€


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Post    Posted on: Wed Apr 16, 2008 1:17 pm
The problem I have with the shuttle is that it lands empty. It takes a module up to the ISSD, but when it comes down there is a load of unnessacery heat shielding covering an empty cargo bay.

I'd like to see a reusable rocket where only part comes back to Earth. Similar to Apollo, but the modules left in orbit would be joined together to build stations.

Why does the ET disintergrate on reentry? Could a parachute be attached to make the system fully reusable?


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Post    Posted on: Thu Apr 17, 2008 10:08 am
Hello, Terraformer,

I am not sure how reusable a vehicle can be only parts of which return to the surface. Some heat shielding will be required - either by a real shield or by a way perhaps similar to SSO.

Because you mention the fact that the Shuttle returns empty it indeed would be the better idea to enable reusable rockets to return loaded with something that is wanted to return to Earth safely without damages caused by reentry. This wouldn't add complexity but increase amounts and numbers.



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Post    Posted on: Thu Apr 17, 2008 3:54 pm
I was thinking maybe sending the modules up unmanned with a much smaller reusable crewed Spacecraft joining the modules up.

How fast does the ET come down to Earth at?


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