Having flown the Acceleron I & II booster a total of 16 times now, we are happy with how it has been performing.
So last night we spent a couple of hours designing the staging mechanism for the booster. And I think we finally have a good plan. The release will be based on a Gardena release mechanism rather than a crushing sleve. The main reason is that with the gardena mechanism, you can release the rocket exactly when needed, rather than when the pressure drops inside the main booster as with a crushing sleve. Also all our existing nozzles will fit the sustainer. The other main reason is that we know that the Gardena mechanism can hold higher pressures up to at least 220+ psi. We want to be able to retain the design once we start reinforcing the bottles. Lastly the crushing sleeve method doesn't lend itself very well to the construction of CD nozzles, which we plan to revisit especially with the sustainer.
Full details of the design will be published once we build it and we know that it works.
Acceleron II has now been disassembled and will get a couple of upgrades:
1. Each booster segment will be extended by a further 2L capacity to help with the greater payload. This means that the total capacity of the booster will be close to 25L.
2. The dummy payload will be replaced by a new payload pod that will house the flight computer, camera, parachute and staging mechanism actuator. The staging mechanism will be mounted just above the pod. The pod will also be used to support the sustainer and protect the payload contents from the spray during separation.
The first sustainer will most likely be based on two 1.25L bottles joined together and will look similar to "OO", with the exception that it will also have a flight computer, camera and side deployment. Eventually when we buy an altimeter we will put that in there as well.
We are more likely to spend this weekend in the workshop rather than launching rockets as we are keen to see how it will go.