Having been given a blacksky AltAcc for my birthday by my wife I decided I needed a better rocket to take full advantage of the AltAcc, for this next Rocket I wanted a rocket that made use of the 2 channels on the AltAcc, the AltAcc is a recording Altimeter that has the ability to set off pyrotechnic charges at the Apogee and at 700-500ft AGL for the deployment of the recovery devices. Also I had always liked staged rockets So I decided to try a staged Rocket, As Most of the kits available through Pete are PML kits the choice I had was limited to 2 kits, option 1 a PML Thunder and lightning, option 2 a PML Eclipse with booster section. Looking at both kits I decided to go with the slender Thunder and Lightning.

Planned Modifications

I had read about several peoples experiences with the CPR coupler that is supplied with the Thunder and Lightning and had decided to not use it instead I would replace the whole of the recovery electronics section with a 9inch section of coupling tube and bulk heads to house the altacc, In the middle of the coupler tube I would add a 2inch section of body tube to aid in the positioning of the coupler ( due to it being riveted in place before each flight)

The second modification was to extend the Stage coupler that houses the timer, I had planned to use blackskys Timer2 but this would not fit in the coupler supplied so a longer section of coupler was cut so as to house the Timer2. A tray made from G10 for the timer. this tray would slip into the interstage coupler and run along slots in strips of wood that were to be fixed to either side of the coupler tube. The next modification was not to cut an access panel in the tube but to have the rear bulkhead to be removable it was to be fixed into position by the use of some captive nuts and bolts.

I also chose not to install the launch lugs provided as a longer launch rod would be required and longer rods may develop whip or flex at launch giving a launch path not as desired. Instead I purchased a Black Sky Launch Rail and fitted the Thunder and Lighting with rail guides.

The final modifications was to fit engine retainers to both stages of the rocket, On the booster stage this meant having the boat tail turned down to  have the retainer slip inside it and also required a section to be remove off the rear of the boat tail.