6 litre with parachute

[160psi]

This is a video from last year of a 6 litre rocket (4 1.5 litre bottles joined in pairs at base with robinson couplings then the two pairs joined neck to neck).

Parachute is tomy timer started by an air flap.

Launch pressure 120psi.

Altitude no idea - any guesses?

[youtube][/youtube]

[Spaceman Spiff]

This is a video from last year of a 6 litre rocket (4 1.5 litre bottles joined in pairs at base with robinson couplings then the two pairs joined neck to neck).

Parachute is tomy timer started by an air flap.

Launch pressure 120psi.

Altitude no idea - any guesses?

[youtube][/youtube]

I would guess 145.25213345 meters!

[WRA2]

This is a video from last year of a 6 litre rocket (4 1.5 litre bottles joined in pairs at base with robinson couplings then the two pairs joined neck to neck).

Parachute is tomy timer started by an air flap.

Launch pressure 120psi.

Altitude no idea - any guesses?

[youtube][/youtube]

My guess would be around 500 feet. Nice job.

What size chute did you use?

[160psi]

This rocket is, alas, no more - so I'm not sure of the chute size, but I think it was about 60cm diameter.

I am currently building a similar rocket but double skinned to take 200psi.

[Spaceman Spiff]

This rocket is, alas, no more - so I'm not sure of the chute size, but I think it was about 60cm diameter.

I am currently building a similar rocket but double skinned to take 200psi.

How do you make a double skinned rocket? Do you have bottles that fit inside each other?

[160psi]

Yes I shrink 2 litre bottles over 1.5 litre bottles in much the same way as described on the air command website, except I use Gorilla glue in between.

They are rock solid when cured and will easily stand 200psi plus for many launches.

I will take some pics next time I do some if you like.

[Spaceman Spiff]

Yes I shrink 2 litre bottles over 1.5 litre bottles in much the same way as described on the air command website, except I use Gorilla glue in between.

They are rock solid when cured and will easily stand 200psi plus for many launches.

I will take some pics next time I do some if you like.

That's interesting. Sounds like it would be pretty stiff. I understand everything except what you do when you have the neck of the bottle. How do you reinforce the neck part?

[160psi]

Here are some pictures of the double skinning process:

The first is a pair of 1.5l bottles joined bottom to bottom with a Robinson coupling, and sanded ready to take the glue. They have been filled with cold water and inflated to about 20psi to make them rigid

bottles ready for reinforcement

DSC02024.JPG (1.37 MiB) Viewed 117 times

The next shows a sleeve from a 2 litre bottle already shrunk on and another sleeve party shrunk over one end.

Middle section shrunk on and next section part shrunk

DSC02026.JPG (1.38 MiB) Viewed 117 times

Next comes the neck - make sure that you shrink towards the bottome so that the bottle is always protected by cold water inside and the glue squeezes out

Neck section being shrunk

DSC02025.JPG (1.38 MiB) Viewed 117 times

The finished neck section - the bit that is unprotected is actually already very strong and will easily stand 250psi - all that remains is to carefully trim any excess glue that comes out as it cures.

finished neck section

DSC02027.JPG (1.22 MiB) Viewed 117 times

Here is one I prepared earlier, clear bottles this time and the glue is cured - total weight of finished pair is just under 200g. You can see the overlap section both sides of the middle which is actually triple walled.

cured pair

DSC02029.JPG (1.38 MiB) Viewed 117 times

The 6 litre rocket will be two such pairs joined.

Hope this helps

[U.S. Water Rockets1]

Here are some pictures of the double skinning process:

The first is a pair of 1.5l bottles joined bottom to bottom with a Robinson coupling, and sanded ready to take the glue. They have been filled with cold water and inflated to about 20psi to make them rigid

DSC02024.JPG

The next shows a sleeve from a 2 litre bottle already shrunk on and another sleeve party shrunk over one end.

DSC02026.JPG

Next comes the neck - make sure that you shrink towards the bottome so that the bottle is always protected by cold water inside and the glue squeezes out

DSC02025.JPG

The finished neck section - the bit that is unprotected is actually already very strong and will easily stand 250psi - all that remains is to carefully trim any excess glue that comes out as it cures.

DSC02027.JPG

Here is one I prepared earlier, clear bottles this time and the glue is cured - total weight of finished pair is just under 200g. You can see the overlap section both sides of the middle which is actually triple walled.

DSC02029.JPG

The 6 litre rocket will be two such pairs joined.

Hope this helps

That's a great mini tutorial on your build process. The pictures show that your method is very strong and not likely to come apart at the joint. Have you had any failures of these bottle splices in the past? The way you have them joined looks like the joint would leak air before the bottles actually exploded. What have you seen in practice?

[160psi]

In practice I have never flown them beyond 200psi, although have pressure tested to 225psi. I have never had a failure yet - one flew about 20 times and was then lost, we never did find it. All the others I have made are still fly-able although the 6 litre I am making at the moment is the first to have two such pairs joined together, the others have either been single bottles or pairs as shown above.

The 6 litre shown in this video was single skinned and did coma aprt at the joints after about 10 launches at 120psi or so and a couple of crashes.

[pudresful]

nice vid I guess 150m and did you use fly cam one 2 I have same broblem with voices

[liftoff]

I can certainly vouch for the gorilla glue, what doesn’t stick the PET stick to your finger for days after if you don’t wear gloves. I gathered you are based in the UK, what 1.5 bottle are you using? I have recently found some 1.25 bottles that Tesco uses for their flavoured sparkling water that might work well.