Video of radio-controlled plane flying into stratosphere and back

[ryoder 1,404]

http://news.yahoo.com/blogs/sideshow/video-radio-controlled-plane-flying-stratosphere-back-055227997.html

"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

[JohnMitchell 14]

Video was out of service.

Sounds like he hoisted a glider using a helium balloon. That would be some real rocket science to ascend a model aircraft that high on engine power.

[theonlyski 3]

http://www.youtube.com/watch?v=rpBnurznFio&feature=player_embedded

Direct link

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[JohnMitchell 14]

Thanks.

Interesting. I would have painted that thing bright orange, wouldn't you?

I think they could have picked better weather, including winds aloft, for the mission, but that is cool.

I've worked a number of high altitude balloon missions over the years. It's an interesting profile.

[Remster 24]

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Interesting. I would have painted that thing bright orange, wouldn't you?

Unless you don't want any passer-by to pick it up and you have a high level of expectation to land it "next to your feet"

Remster

[billvon 2,450]

>That would be some real rocket science to ascend a model aircraft that high on engine power.

I've often thought about a hybrid rocket with a large booster made entirely out of propellant (skin and all.) The top of the rocket contains the glider and a tank of liquid oxygen. The rocket is launched and gets the glider to altitude, then continues its burn until the entire booster is consumed (or the remaining pieces are so small/light that they are not an issue for recovery.) The glider then returns.

[quade 3]

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I've often thought about a hybrid rocket with a large booster made entirely out of propellant (skin and all.)

How do you envision that working? Don't the walls of the rocket need to contain pressure so it can be forced out the back end nozzle? To me that implies a certain amount of robustness and resistance to being consumed by fire. If the propellant burned even microscopically different from one part of the wall to another, when it finally burned through wouldn't that send pressurized gasses out of it and make the rocket unstable?

quade -
The World's Most Boring Skydiver

[kallend 1,659]

Quote

Quote

I've often thought about a hybrid rocket with a large booster made entirely out of propellant (skin and all.)

How do you envision that working? Don't the walls of the rocket need to contain pressure so it can be forced out the back end nozzle? To me that implies a certain amount of robustness and resistance to being consumed by fire. If the propellant burned even microscopically different from one part of the wall to another, when it finally burned through wouldn't that send pressurized gasses out of it and make the rocket unstable?

With a well designed propellant grain and careful manufacturing the propellant could be its own container, and "nozzle" could be an aerospike made of propellant.

Just musing, I don't know what Bill had in mind.

...

The only sure way to survive a canopy collision is not to have one.

[quade 3]

What kind of witchcraft is this? How the hell would you be able to keep the aerospike burning exactly correct so it maintains its shape? And how are you guiding this?

Edited to add:

http://www.youtube.com/watch?v=PBvfIpRsWpc

Which is a solid rocket with an aerospike, but not the way I understood it as described by bill, which would be self consuming. The walls are still a structural element that contain the propellant and the aerospike is a separate and very solid component which is not consumed by use.

quade -
The World's Most Boring Skydiver

[kallend 1,659]

Quote

What kind of witchcraft is this? How the hell would you be able to keep the aerospike burning exactly correct so it maintains its shape? And how are you guiding this?

Edited to add:

http://www.youtube.com/watch?v=PBvfIpRsWpc

Which is a solid rocket with an aerospike, but not the way I understood it as described by bill, which would be self consuming. The walls are still a structural element that contain the propellant and the aerospike is a separate and very solid component which is not consumed by use.

Gee, Paul, it's not exactly rocket science.

(Maybe Bill will tell us what he had in mind)

...

The only sure way to survive a canopy collision is not to have one.

[riddler 0]

Linear aerospike engines were attempted on the X-33 project, to be named VentureStar, back in the late 90s as a shuttle replacement. The US Air Force evaluated the prototype and considered them an abject failure. It's one of many reasons we don't have a replacement for the shuttle today.

Trapped on the surface of a sphere. XKCD

[billvon 2,450]

> Don't the walls of the rocket need to contain pressure so it can be forced out the back end nozzle?

Yes. Carbon fiber, for example, is both very strong and very flammable in pure oxygen. A composite that used carbon fiber as the outer strength element in a matrix of propellant might work pretty well.

>If the propellant burned even microscopically different from one part of the wall to
>another, when it finally burned through wouldn't that send pressurized gasses out of it
>and make the rocket unstable?

Yes. At that point you throttle back to minimum oxidizer flow and just let the rest of the casing burn. At some point you'll lose structural integrity and the rest of the booster will effectively "fall off" but the goal would be to get most of the booster consumed.

An alternative is to wait for burnthrough then max out the oxidizer flow and just blow the booster to bits. You go unstable in both cases but since you no longer have any significant thrust you just end up in an unusual attitude.