Disastrous launch attempt :(

[dongfang]

Hi,

I tried to get some beautiful pictures of the new snow today, from above, with a 6 * 2 liter rocket that I have had around for some time.

There was a FlyCamOne2 on it, and an RC receiver with a battery and a servo to deploy the parachute. Although I had previously tested the rocket to 8 bar, today it decided to fail at 7, and before the first launch!

The worst thing was that the camera (CHF 100), the receiver (CHF 150), the battery (CHF 25) and the servo (CHF 20) had all been blasted in different directions and had disappeared in the snow. And that one of the others there was a little dissatisfied with explosions and things flying around But at least the top half of the rocket came down nicely on the chute (and the nosecone is on orbit or something - never saw it).

Anyway, that same guy helped me search for the remains of my equipment, and we managed to recover the servo, the receiver and the battery! Not bad at all..

The losses were: One rocket (exploded), one parachute deployment nosecone (lost), one LiPo battery (lost) and one damaged receiver. And no pictures with snow.

I will have to implement remote controlled launch, and also actually use it.

Regards
Soren

[rockets-in-brighton]

Sorry to hear about your loss. From your description it sounds like you got off lightly as far as material losses were concerned. Had this pressure vessel been used previously, and at a similar pressure? Had it been in any hard landings before, that might have weakened it?

[rockets-in-brighton]

Oh wait, did you lose the camera as well? 8-(

[dongfang]

Hi,

Oops I meant we recovered the camera, not the battery.

The pressure vessel was once tested to 8 bar, but it had never flown before.

Regards
Soren

[monboy10]

what did you use to make the fins?

[dongfang]

Hi,

The fins are 6 mm Depron. Any well-assorted R/C model shop should have it. It's a foam material mostly used for model airplanes etc.

I cut 2 side pieces out of it, with 4 triangular spars(?) to make the fins hollow, thick and stable.

Most people will glue it with 5 minute or 90 minute epoxy, but I use polyurethane (PU) cement instead: It's cheaper, needs no preparation/mixing, it contains no allergenic phenols etc., it has the same color as the foam, it is flexible and will no crack, and it is more than strong enough anyway. But it is slower all right.

Regards
Soren

[monboy10]

ok thanks

[Spaceman Spiff]

Sorry to hear your snow launch didn't happen. That's a shame. At least you were able to recover the camera and electronics. I never anticipated that things could get lost in the snow. That's something people who launch in the winter may not have considered either! Now we know!

[RaZias]

I think the plastic is more prone to break at icy temperatures.
Maybe that is way it blasted.

Once a rocket I had blasted at 80 psi in the launch pad because it had a area less than cm2 pressed inward.


I asking you a favour, could post pictures more detailed of your "air/water mixer system" ?

[Aquafire]

I think the plastic is more prone to break at icy temperatures.
Maybe that is way it blasted.

Once a rocket I had blasted at 80 psi in the launch pad because it had a area less than cm2 pressed inward.


I asking you a favour, could post pictures more detailed of your "air/water mixer system" ?

What if a person were to place warmed water inside the rocket in cold days? Would the plastic be warmed by the water enough to remain flexible?

[Spaceman Spiff]

I think the plastic is more prone to break at icy temperatures.
Maybe that is way it blasted.

Once a rocket I had blasted at 80 psi in the launch pad because it had a area less than cm2 pressed inward.


I asking you a favour, could post pictures more detailed of your "air/water mixer system" ?

What if a person were to place warmed water inside the rocket in cold days? Would the plastic be warmed by the water enough to remain flexible?

That might be worse because you would have a temperature differential at the level of the water line and that would cause the bottle to expand in an uneven manner and probably put stresses on the bottle that it wasn't designed for.

[RaZias]

Maybe envolving the rocket in neoprene ?

[dongfang]

Hi,

I asking you a favour, could post pictures more detailed of your "air/water mixer system" ?

See this thread.

A good jet:barrel ratio is 2:1. That is, the total area of the holes in the side of the pipe is about 2 * the inner cross section area of the pipe. I don't know if other ratios are better - only that 1:1 performed terribly (no thrust).

It could also be worthwhile experimenting with many small vs. few large holes.

It really improves performance - I will see if I can find that old sheet of paper with "before" and "after" flight times that I recorded. Something like from 6.4 to 7.5 seconds average, over 3 flights.

Regards
Soren

[Alex]

yikes, well this happens, I've had about a dozen Model rockets explode on me mid flight....It's not a nice sight...Good luck next time....This was just your ''Challenger'' or Apollo 13 without the happy ending..... Give er' another go and you'll be fine.

[CSAldridge]

ok, who wants to build a new winter launcher with a bunch of hair dryers arrayed around the rocket keeping everything toasty during pre-launch.

you know you want to... 8P