Made some changes to the 9L rocket and launchtube.
On earlier videos from the launches of the 9L rocket I saw that the launchtube bended during lift off.
I assumed that this was caused by the internal pressure off the rocket, as it goes up, it pushes the launchtube out and thus bending it at the end of the launchtube phase.
I used 3/4" (inner diam.) PVC piping used for electric wiring for it, this fits nicely in the bottle nozzle that is 22mm.
This launch video is with a stiffend launchtube (aluminum tube inside the PVC tube). Also i extended the 9L with a extra bottles wich where a little less heavy.
The result is almost the same weight and a volume that is increased to 10 Liter.
In the video you can see that the tube stays straight. The rocket is still has an small angle to the right at the end of the launchtube phase.
But i like the result with the stiff tube, so this will be a keeper.
Flight is ok, almost straight up. Timed the apogee at 5.4 sec, a little less compared with the predicted 5.8 sec (and apogee from 185 meter) from rocketsim.
At the end of the launchtube phase you hear a distinct "popping" sound, this is the pressurized air that suddenly is allowed to escape from the luanchtube.
There was no time for a second launch, because it started to rain.
Well more (pressure) next time.