Rocket powered vehicle and ejection charge

[Supern0va]

I am trying to use low power rocket motors to propel a vehicle so I can test its flight performance, and I have a question about ejection charges. I looked and found two low power motors with no ejection charges, but one would not be strong enough for my vehicle, and for the other I couldn't find any sellers.
A short description of my vehicle is a cylinder with wings on it, and a hole in the back to insert the motor. It will be 3D printed, and will be used to test in a real world situation the flight performance of different wing shapes. 1
If I put a motor with an ejection charge into the vehicle directly, what would I need to do to keep it safe for reuse after launching?
Personally, right now I am thinking maybe a hole through the center of my cylinder to allow the pressure to go out the front, but I am unsure if it will be able to properly vent the gases. I also have fears that it might mess with the aerodynamics of my vehicle.
Thank you!

 

[Steve Shannon]

A wind tunnel would be a much better way to test your wings. Horizontally launched rockets don’t fly long.
Otherwise, look for motors that have a P (for plugged) after the dash.

 

[Antares JS]

First, DO NOT attempt to launch anything horizontally with a rocket motor. Rocket gliders and even cruise missiles launch vertically (or close to it) and then tip over.

Second, as above, a wind tunnel is a much better idea. It's a much more controlled environment, much easier to get the data you need on these different wings, and it's entirely possible to build a homemade one. A wing in a wind tunnel will sit in one place where you can watch what it does. A wing on a rocket is going to zip out of easy view and it's going to be hard to make observations.

 

[Supern0va]

First, DO NOT attempt to launch anything horizontally with a rocket motor. Rocket gliders and even cruise missiles launch vertically (or close to it) and then tip over.

Second, as above, a wind tunnel is a much better idea. It's a much more controlled environment, much easier to get the data you need on these different wings, and it's entirely possible to build a homemade one. A wing in a wind tunnel will sit in one place where you can watch what it does. A wing on a rocket is going to zip out of easy view and it's going to be hard to make observations.

I am planning on making a heavy craft that won't fly too far, and I will have a large area to "catch" the rocket so it won't cause harm to anyone.
As for building a wind tunnel, with my constraints it will be near impossible to build and gather observations, and I don't need anything precise just a few basic data points.

 

[Art Upton]

I am planning on making a heavy craft that won't fly too far, and I will have a large area to "catch" the rocket so it won't cause harm to anyone.
As for building a wind tunnel, with my constraints it will be near impossible to build and gather observations, and I don't need anything precise just a few basic data points.

What basic data points would you get from this if any about a wing shape?
Just curious, as I don't know.

 

[cls]

Sounds like your launch, cruise, landing range is confined well enough. Why not use bungees to accelerate the test vehicle? Cheap, repeatable, lower risk.

 

[Supern0va]

Sounds like your launch, cruise, landing range is confined well enough. Why not use bungees to accelerate the test vehicle? Cheap, repeatable, lower risk.

I think that's a good idea, but my one concern would be how to release the vehicle from the chord so it doesnt mirror the movement of the chord, as well as how to keep the vehicle airborne for a long enough distance for measurements to be distinct. That is a good idea though, thank you.

 

[Supern0va]

What basic data points would you get from this if any about a wing shape?
Just curious, as I don't know.

Really just the speed at a set point in flight (measured using a black and white board behind the flight path and a camera), the height at that time, the distance of flight, and the time of flight.
I am doing a project where I am attempting to find the performance of diferent wing shapes at low speed low altitude flight.

 

[jadebox]

Model rocket motor performance might not be consistent enough to support your experiment. And you would be limited by not having much choice of the thrust they supply.

One idea that comes to mind is using compressed air to launch the test vehicles. I think that would provide a means of propulsion that is more repeatable and tuneable.

 

[cls]

I think that's a good idea, but my one concern would be how to release the vehicle from the chord so it doesnt mirror the movement of the chord, as well as how to keep the vehicle airborne for a long enough distance for measurements to be distinct. That is a good idea though, thank you.

plenty of prior art for glider hooks, look around, ask model aircraft folks.

 

[lakeroadster]

Sounds like your launch, cruise, landing range is confined well enough. Why not use bungees to accelerate the test vehicle? Cheap, repeatable, lower risk.

Or a Crossbow arrangement....​

 

[sr205347d]

For a controlled release, I suggest putting your flight vehicle on a sled that rides on a track or rail. Accelerated by bungee, pneumatics, or whatever, when it reaches the end, the sled is stopped and the flight vehicle continues on.

 

[sr205347d]

This, from Lowe's should make a great bungee: