Jason, That doesn't negate the fact that if you put an insulator behind the metal, yes, it protects the structure behind the metal but it only makes it so the metal melts quicker.
Quote from: mlorrey on 05/02/2010 08:59 pmThe first Chinese Shenzhou capsule used water saturated bamboo, which allowed for the water to create a boundary layer as it steamed out of the pores of the bamboo.Why only the first one?
The first Chinese Shenzhou capsule used water saturated bamboo, which allowed for the water to create a boundary layer as it steamed out of the pores of the bamboo.
Leading edge cooling has its' own issues, but again, the use of small, relatively low powered LH2/LOX thrusters, strategically located just above the leading edge, and semi-conformally shaped,could, in theory, produce a sheath of gasses around the craft, both above and below the leading edge of the craft, with the majority of the sheath going over the top of the craft, adding to the lift. Admittedly, this idea was cribbed from Supercavitation Torpedoes, (http://en.wikipedia.org/wiki/Supercavitation) but as this technique reduces the drag in water enough to allow rocket powered torpedoes to travel underwater at speeds in excess of 100 knots, (The fastest US subs can normally only do about 25 to 30 knots) I figure that a similar system should be able reduce drag, add a bit of lift, and cool the leading edges of a hypersonic aircraft. I realize that hydrodynamics and aerodynamics are to seperate sciences, but as both are based in fluid dynamics, there may be enough similarity to be able to use this technique, or something similar to it.Jason
Quote from: Proponent on 05/03/2010 04:07 amQuote from: mlorrey on 05/02/2010 08:59 pmThe first Chinese Shenzhou capsule used water saturated bamboo, which allowed for the water to create a boundary layer as it steamed out of the pores of the bamboo.Why only the first one?LOL I have no idea why, you should ask the Red Army next time you see them. I hear their transparency policies are unmatched outside of North Korea.My opinion is that some political types thought that bamboo was too stereotypically chinese and made them look like primitives to the roundeyes in the west.
Cheap, disposable, made from naturally grown and redily available materials, lightweight, uses water as a cooling system, can add layers as needed for higher velocity reentry? Gee, I wish NASA thought so primatively! Sounds to me like they used an economical, readily availabe natural resource in a VERY clever way! I say; Unless there is some issue where the really NEED to use another TPS material, the Chinese SHOULD continue to use water soaked bamboo as a TPS material! Maybe, for disposable capsules, we should consider growing a grove of bamboo outside of the VAB, set up a "Basket Weavers" facility near by, (yes, I know that they wouldn't actually be weaving baskets, probably be more like rendering it down to fiber and applying it like layers of fiberglass to the hull as TPS material) and apply it on site. To be honest, I look at it as a form of the KISS principle. Keep It Simple Stupid! We should applaud the Chinese for their solution.
Quote from: JasonAW3 on 05/29/2010 08:55 am Cheap, disposable, made from naturally grown and redily available materials, lightweight, uses water as a cooling system, can add layers as needed for higher velocity reentry? Gee, I wish NASA thought so primatively! Sounds to me like they used an economical, readily availabe natural resource in a VERY clever way! I say; Unless there is some issue where the really NEED to use another TPS material, the Chinese SHOULD continue to use water soaked bamboo as a TPS material! Maybe, for disposable capsules, we should consider growing a grove of bamboo outside of the VAB, set up a "Basket Weavers" facility near by, (yes, I know that they wouldn't actually be weaving baskets, probably be more like rendering it down to fiber and applying it like layers of fiberglass to the hull as TPS material) and apply it on site. To be honest, I look at it as a form of the KISS principle. Keep It Simple Stupid! We should applaud the Chinese for their solution.It isn't a new idea. The Russians used wood on their early warheads. The issue is voids and discontinuities in the wood and fibers, which makes it not reliable for manned use.
Bamboo fibers, (by the way) can also replace carbon fibers in many applications for composites.Randy
The solution to TPS? Why, base first reentry of course.If do a rocket powered landing you can use the engine exhaust plume to help punch your way through the atmosphere. Plus, the rocket engine was already designed to handle high temperatures using ablatives, film cooling, transpiration cooling, or whatever.It's a bit of a waste not to use all that reentry heat for something.
Quote from: RanulfC on 06/10/2010 07:10 pmBamboo fibers, (by the way) can also replace carbon fibers in many applications for composites.RandyHmmmm... I did not know that. How's the durability, weight and stress levels compare to carbon fiber?
Quote from: JasonAW3 on 06/10/2010 10:24 pmQuote from: RanulfC on 06/10/2010 07:10 pmBamboo fibers, (by the way) can also replace carbon fibers in many applications for composites.RandyHmmmm... I did not know that. How's the durability, weight and stress levels compare to carbon fiber?Comparable in many cases and as I understand it not many people knew much about the idea until about 5 years ago when there was an major shortage of carbon fibers due to high demand. It seems that some manufacturers had replaced carbon-fibers with bamboo but where still selling the product as having CFs in them. I found out about it because a local bike frame builder stated directly though he'd read the studies and reports on replacing CF with bamboo his company would continue to depend only on CFs as that was what they felt was the better option.A couple of google searchers later I found out that in order to NOT get sued into oblivion those companies that had been using bamboo instead of CFs had to both sponser a new series of studies and inform all the customers who had been sold non-CF equipment of that fact and offer free replacement. For the most part, while people were frakked about paying higher prices and not getting actual CFs once the companies payed back the 'over-charges' the majority went ahead and kept the bamboo based equipment as they felt there was no major difference between the two EXCEPT for price.Several of the companies now market bamboo in composites instead of CFs.Randy
Some interesting TPS-related concepts I came across on NTRS: