I recently redesigned my old Alien Atmospheric probe, and wanted to post pics of the build process.
The previous version had stability issues - the main fins needed to be wider, and the strakes seemed to introduce even more instability (particularly since they were so long it was really difficult to get the glued on straight).
I redesigned the rocket, keeping the older nosecone assembly, but upping the main body tube from a BT-55 to a BT-60. I cut down an BT-60 nosecone to make a transition to insert the old BT-55 nosecone into. I also used an BT-60 plastic tailcone. I also upped the rear fins width and went from 3 fins to 4, and added an integral semi-strake attached to the main fin.
Old rocket:
New version:
I built the engine assembly first, using an BT-60 plastic transition off of an Estes nosecone. I had to widen up the slot for the engine hook, as it appeared to be set up for the smaller 18/24mm engine hook.
Otherwise, it is of a fairly standard construction, except that the rear of the engine tube buts up against a lip on the inside of the transition smaller end.
Engine mount with transition:
Nosecone I cut down to make the forward transition between the BT-60 main body tube and the BT-55 nosecone assembly:
Transition with old nosecone assembly alongside (I won't be reusing the old nosecone as it has noseweight epoxied in it that the new design does not need, so ordered a replacement nosecone from Sirius Rocketry).
Transition with nosecone in place to show how it looks:
4 fins and front strakes that will attach to the front of the fins, nothing special. 1/8" balsa here. I won't be able to attach these yet, as I have to epoxy the engine mount in place first, and the weather here has not been cooperative. The rear of the fins taper down to match the plastic tailcone.
More pics as construction proceeds.
The previous version had stability issues - the main fins needed to be wider, and the strakes seemed to introduce even more instability (particularly since they were so long it was really difficult to get the glued on straight).
I redesigned the rocket, keeping the older nosecone assembly, but upping the main body tube from a BT-55 to a BT-60. I cut down an BT-60 nosecone to make a transition to insert the old BT-55 nosecone into. I also used an BT-60 plastic tailcone. I also upped the rear fins width and went from 3 fins to 4, and added an integral semi-strake attached to the main fin.
Old rocket:
New version:
I built the engine assembly first, using an BT-60 plastic transition off of an Estes nosecone. I had to widen up the slot for the engine hook, as it appeared to be set up for the smaller 18/24mm engine hook.
Otherwise, it is of a fairly standard construction, except that the rear of the engine tube buts up against a lip on the inside of the transition smaller end.
Engine mount with transition:
Nosecone I cut down to make the forward transition between the BT-60 main body tube and the BT-55 nosecone assembly:
Transition with old nosecone assembly alongside (I won't be reusing the old nosecone as it has noseweight epoxied in it that the new design does not need, so ordered a replacement nosecone from Sirius Rocketry).
Transition with nosecone in place to show how it looks:
4 fins and front strakes that will attach to the front of the fins, nothing special. 1/8" balsa here. I won't be able to attach these yet, as I have to epoxy the engine mount in place first, and the weather here has not been cooperative. The rear of the fins taper down to match the plastic tailcone.
More pics as construction proceeds.
