# Dropping objects from high up

1. Jul 4, 2016

### saber08

Hello everyone,

I need some idea brainstorming. I am doing an experiment where I drop objects in to water (in a lake) and measure the impact forces. Now, the thing is the objects need to be dropped from as high as 30 meters up in the air and other lower heights as well. Can anyone think of a good idea to take the objects to that height? I tried using a drone, but it didn't work very well at that location. Any ideas would be greatly appreciated.

Thanks.

2. Jul 4, 2016

3. Jul 4, 2016

### saber08

Well, I am actually looking for something that is more stable and easier to control.

4. Jul 5, 2016

### 256bits

High board on a swimming pool.
Access might be difficult to acquire, or will require some convincing persuasion.

5. Jul 5, 2016

### Baluncore

There are probably laws against dropping things off bridges, tower blocks or hotels. You could have a fixed height with a variable length of cord. Lower the object to the drop height, then release it. You could reduce the size of the pond and increase the safety by sliding the object down a vertical guide wire.

Another possibility would be to generate the velocity equivalent to a particular drop height by propelling the object downwards using something like a crossbow, elastic, compressed air or an orange gun. You might then be able to do all your experiments on a test stand less than 20 feet high. You would need to measure the speed of the object with an acoustic doppler or radar sensor.

6. Jul 8, 2016

### Shane Gribben

Why not drop from lower heights and use scaling laws to factor up to the desired heights

7. Jul 8, 2016

### Baluncore

Another alternative. What goes up must come down, so you might throw it upwards at a velocity slightly greater than you want it to come down. It could have a parabolic trajectory, from land to water.

8. Jul 9, 2016

### CWatters

Can you use compressed air to "fire" the object downwards from a lower height?

9. Jul 10, 2016

### Staff: Mentor

Climb to the top of a 30 m sailboat mast, then get the skipper to heel the vessel until you are over water. Whee

10. Jul 22, 2016

### Ketch22

Do you have access to a competitive swimming pool. The 10m, 20m, 30m platforms seem like they would be perfect for your tests. Failing the pool being available. What are the weights you are working with? It would be relatively easy and repeatable to create a slingshot of sorts that would launch somewhat soft and achieve said elevation. That being accomplished any body of water would be serviceable. You would need to compensate for the slight angular impact. I often launch water balloons several hundred feet but not for scientific purposes.