Air Command: Index of Recovery Systems

[U.S. Water Rockets1]

Hi USWR, how are you? yes its been a while. We're always happy to get more help and suggestions for links for the guide. We are continuing to gather further recovery system sources in the background and will do another update over the next few weeks, but it is slow going.

Good to see you guys working on Project 3000 as well. Looks like a very interesting build!

Hi George,

We're doing well (just cold at the moment). We have some footage of one of our early rockets using backglider recovery we could put up on our site if you think you can use a demonstration video.

So many projects, and so little time...

Hello USWR,

Sorry to hear about the cold, a bit warm over here at the moment (~110F at times!) If you do have a video of backgliding recovery we'd like to add it to the recovery guide. Please let us know of the link and we'll add it.

"So many projects, and so little time" ....couldn't agree more!

Cheers

- George

Hello George,

With the high temperatures it must make things very dry. That must make pyro rockets a dangerous hobby.
We hope you everyone there is safe from those fires we have been seeing on the news. That is a very sad story. Hopefully the persons who caused that disaster will be caught.

[Brian]

can backgliders naturally backglide or do they need a deployment system

[rockets-in-brighton]

can backgliders naturally backglide or do they need a deployment system

Backgliding happens when the rocket body has a particular configuration. To achieve that, you can build a rocket body that has a movable centre of gravity (change the shape, split into multiple parts, drop the nosecone, whatever) or you can build one that changes centre of lateral area/centre of pressure (movable fins, flip-out fins, etc) or you can build one that has a backglider configuration all the time. The last method doesn't need anything to deploy.

[Tim Chen]

can backgliders naturally backglide or do they need a deployment system

Backgliding happens when the rocket body has a particular configuration. To achieve that, you can build a rocket body that has a movable centre of gravity (change the shape, split into multiple parts, drop the nosecone, whatever) or you can build one that changes centre of lateral area/centre of pressure (movable fins, flip-out fins, etc) or you can build one that has a backglider configuration all the time. The last method doesn't need anything to deploy.

I don't think anything has to move for backgliding to work. There's supposed to be a magic ratio of GC to CP that makes it happen naturally yet the rocket will fly stable under thrust.

[rockets-in-brighton]

can backgliders naturally backglide or do they need a deployment system

Backgliding happens when the rocket body has a particular configuration. To achieve that, you can build a rocket body that has a movable centre of gravity (change the shape, split into multiple parts, drop the nosecone, whatever) or you can build one that changes centre of lateral area/centre of pressure (movable fins, flip-out fins, etc) or you can build one that has a backglider configuration all the time. The last method doesn't need anything to deploy.

I don't think anything has to move for backgliding to work. There's supposed to be a magic ratio of GC to CP that makes it happen naturally yet the rocket will fly stable under thrust.

Yes, that's what I was trying to describe, but not very well. The correct configuration (as I understand it) is to arrange for the centre of gravity to be positioned between the centre of lateral area and the barrowman centre of pressure, with the order (from nose to tail) CLA - CG - BCP.

You can either make this as a permanent configuration, or trigger a change in one or more of the three parameters at the time you want the backgliding to occur.

[Andromeda]

I once saw a pyro rocket which had the odd recovery system which was made to eject the fins at apogee. The fins and the rocket were connected by a string and the whole thing was made to tumble back down but it reportedly glided much of the time.

[rockets-in-brighton]

I once saw a pyro rocket which had the odd recovery system which was made to eject the fins at apogee. The fins and the rocket were connected by a string and the whole thing was made to tumble back down but it reportedly glided much of the time.

Yes, I guess that's the kind of thing that Brian was referring to. There were a few other examples in the recovery systems index that worked in a similar way.

[Spaceman Spiff]

That's a pretty cool looking video. It comes down very gracefully. I think I would be worried about getting caught by a tree if my rocket came down like that!

[Tim Chen]

Here is the side gliding video. It was converted from an old recording we did in 2003.

U.S. Water Rockets:
That's a great example of a backgliding recovery.

I was reading another discussion and someone had mentioned that water builds up inside the rocket and a backglider will only be good for 4 flights before it gets too heavy in the nose from water buildup and it will crash. Did you guys ever notice anything like that?

[josh333]

thanks

[U.S. Water Rockets1]

Here is the side gliding video. It was converted from an old recording we did in 2003.

U.S. Water Rockets:
That's a great example of a backgliding recovery.

I was reading another discussion and someone had mentioned that water builds up inside the rocket and a backglider will only be good for 4 flights before it gets too heavy in the nose from water buildup and it will crash. Did you guys ever notice anything like that?

If you think about it, that's a pretty silly theory. There's no way for water to build up inside a water rocket on consecutive flights. If you fill it to the same level and use the same pressure on multiple flights, it will drain the same amount each time, leaving the same amount behind for any number of flights. It sounds like your source needs to spend some time with some other water rocket enthusiasts.

The real reason for crashing these rockets is very simple. They are stable in two flight configurations: horizontal and vertical. The horizontal flight configuration is very easy to disturb, resulting in transition to the vertical mode, which happens to be very hard to disturb. A slight gust of wind can easily cause a switch from horizontal to vertical mode. This results in a crash.

Simply put, a backglider should not be flown unless there is absolutely no wind.

[RaZias]

I think water-build up is only a theory but it was no sense.

You can think ok...so if the last water drops remains (because a rocket won´t get always dry inside) some of them will stick into the microscopic impurities that might stay in the top part (ex: fingertips from construction), in the end those extra-grams will make the rocket became unstable.

Why this theory fails ? Simple:

1 - When you fill a rocket with water, one method is to do it up sidedown so the water will go to the top of the rocket. Therefore it would be common to see some instability, what´s not true.

2 - 99.9 % of the water is ejected right on the launch so it´s impossible to have big amounts of water in the top.

3 - Small drops of water on the top (due to refuelling) won´t make the rocket go unstable.

[Tim Chen]

I think water-build up is only a theory but it was no sense.

You can think ok...so if the last water drops remains (because a rocket won´t get always dry inside) some of them will stick into the microscopic impurities that might stay in the top part (ex: fingertips from construction), in the end those extra-grams will make the rocket became unstable.

Why this theory fails ? Simple:

1 - When you fill a rocket with water, one method is to do it up sidedown so the water will go to the top of the rocket. Therefore it would be common to see some instability, what´s not true.

2 - 99.9 % of the water is ejected right on the launch so it´s impossible to have big amounts of water in the top.


I remember someone saying that if the rocket spins a lot on ascent that a lot of the water can be pushed out to the sides like a centerfuge and it doesn't get forced out by the air. This would leave a good amount of water inside to throw the rocket off balance.


3 - Small drops of water on the top (due to refuelling) won´t make the rocket go unstable.

[Andromeda]

I remember someone saying that if the rocket spins a lot on ascent that a lot of the water can be pushed out to the sides like a centerfuge and it doesn't get forced out by the air. This would leave a good amount of water inside to throw the rocket off balance.

Tim, you mixed up your reply inside the quote. I cut it out for ya.

[Tim Chen]

I remember someone saying that if the rocket spins a lot on ascent that a lot of the water can be pushed out to the sides like a centerfuge and it doesn't get forced out by the air. This would leave a good amount of water inside to throw the rocket off balance.

Tim, you mixed up your reply inside the quote. I cut it out for ya.

Oops! Thanks for fixing it.