Author Topic: Stratolaunch Announcement, Updates and Discussion  (Read 375460 times)

Online matthewkantar

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Re: Stratolaunch Announcement, Updates and Discussion
« Reply #1760 on: 12/22/2016 04:30 PM »
The picture with Allen standing on the wing is surprising to me. I can't tell for sure what is a mat laid down to protect the wing surface, and what is actual wing, but it looks like there are many many fasteners sticking out of the wing surface. Would seem that this eats into the advantages of composite construction in two ways. It makes for an aerodynamically dirty surface and requires hard points and washering all over the place to spread the loads out and create flanges.

I guess we will never know, but I am curious about the magnitude of the weight saved with composite construction in this project.

Matthew

Offline Robotbeat

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Re: Stratolaunch Announcement, Updates and Discussion
« Reply #1761 on: 12/22/2016 06:15 PM »
Reminds me of the Spruce Goose. Carbon Cockatoo?

Not a bad choice of moniker.. but since Cockatoos tend to be (a) big, (b) proud, (c) noisy and (d) incredibly destructive, we'll need to wait for flight test to tell if it fits.
I think it may be a better fit for ITS. But I hope not.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline KSC Sage

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Re: Stratolaunch Announcement, Updates and Discussion
« Reply #1762 on: 12/22/2016 06:37 PM »
The picture with Allen standing on the wing is surprising to me. I can't tell for sure what is a mat laid down to protect the wing surface, and what is actual wing, but it looks like there are many many fasteners sticking out of the wing surface. Would seem that this eats into the advantages of composite construction in two ways. It makes for an aerodynamically dirty surface and requires hard points and washering all over the place to spread the loads out and create flanges.

I guess we will never know, but I am curious about the magnitude of the weight saved with composite construction in this project.

Matthew
When I visited their manufacturing facility they explained the composite construction doesn't save much weight.  What it does do is it allows them to reshape and slightly change the plane's OML while in construction and later during testing.

Offline CameronD

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Re: Stratolaunch Announcement, Updates and Discussion
« Reply #1763 on: 12/22/2016 11:00 PM »
The picture with Allen standing on the wing is surprising to me. I can't tell for sure what is a mat laid down to protect the wing surface, and what is actual wing, but it looks like there are many many fasteners sticking out of the wing surface. Would seem that this eats into the advantages of composite construction in two ways. It makes for an aerodynamically dirty surface and requires hard points and washering all over the place to spread the loads out and create flanges.

I guess we will never know, but I am curious about the magnitude of the weight saved with composite construction in this project.

Matthew
When I visited their manufacturing facility they explained the composite construction doesn't save much weight.  What it does do is it allows them to reshape and slightly change the plane's OML while in construction and later during testing.

When the weight saved by going to composite construction on a B777 equates to several extra passengers and slightly longer range, that sounds strange to me.  Precisely how much does depend upon exactly which structures you're using the composites for, but that it doesn't save "much" does sound strange to me.  Maybe they're not using a lot of composites in the end?

For one-off construction and complex structures, composites make a lot of sense but for simpler structures like spars, beams, landing gear and seat rails, aircraft-grade alloy is cheaper to buy and easy to machine, so not so much.  Cost can go either way.  As with most things aerospace, I guess the final answer is "it depends".. :)
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.

Online Lars-J

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Re: Stratolaunch Announcement, Updates and Discussion
« Reply #1764 on: 12/22/2016 11:51 PM »
For one-off construction and complex structures, composites make a lot of sense but for simpler structures like spars, beams, landing gear and seat rails, aircraft-grade alloy is cheaper to buy and easy to machine, so not so much.  Cost can go either way.  As with most things aerospace, I guess the final answer is "it depends".. :)

I think much of this in aerospace can be explained by the old adage "when all you have is a hammer, every problem looks like a nail". If you have experience with composites, you tend to use them even when you should not. And vice versa.
« Last Edit: 12/23/2016 12:04 AM by Lars-J »

Offline CameronD

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Re: Stratolaunch Announcement, Updates and Discussion
« Reply #1765 on: 12/23/2016 01:28 AM »
For one-off construction and complex structures, composites make a lot of sense but for simpler structures like spars, beams, landing gear and seat rails, aircraft-grade alloy is cheaper to buy and easy to machine, so not so much.  Cost can go either way.  As with most things aerospace, I guess the final answer is "it depends".. :)

I think much of this in aerospace can be explained by the old adage "when all you have is a hammer, every problem looks like a nail". If you have experience with composites, you tend to use them even when you should not. And vice versa.

Hmm.. that hasn't been my experience working with Boeing/Airbus: in airliner fabrication historically they've been reluctant to use composites for anything serious and it's only been relatively recently (last 15 years or so) that they've both embraced the "plastic plane" concept with both arms.  I guess you could argue that now they've gone too far the other way?

How I do miss the old chemi-mill line.  Some of the parts you could fabricate were works of art!
   
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 Robotbeat

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Re: Stratolaunch Announcement, Updates and Discussion
« Reply #1766 on: 12/23/2016 01:52 AM »
Part of the reason they don't save much weight is that we're still refining our models of damage tolerance (etc!) for composites. They're a much more complex material. So we end up putting a lot of margin in various steps. What you end up with is matrginal weight savings, some manufacturing advantages for certain types of shapes, and actually a very sandbagged design with lots of hidden margin that we're not certified to take advantage of but which exists nonetheless. So you could argue there's a big safety factor there as well.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Online FutureSpaceTourist

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Re: Stratolaunch Announcement, Updates and Discussion
« Reply #1767 on: 03/10/2017 02:32 PM »
New article by Alan Boyle but not much new info:

Quote
Billionaire Paul Allen hopes his ‘ginormous’ Stratolaunch plane will fly this year

http://www.geekwire.com/2017/paul-allen-ginormous-stratolaunch-super-plane/

Online FutureSpaceTourist

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Re: Stratolaunch Announcement, Updates and Discussion
« Reply #1768 on: 04/14/2017 08:21 PM »
Quote
Looks like the Stratolaunch website has some new (or at least new-ish) photos of its aircraft under construction: stratolaunch.com

https://twitter.com/jeff_foust/status/852978324813090816

I've attached the images I found.

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