While this one isn't an original design. I just had to build one for club demonstrations & displays. I don't recall clearly where I saw this little beasty. MR or Estes club??? but all the parts are Estes. The original wasn't quite the size I built as I was going for the Largest Model Rocket I could Launch under 1 pound. Back in the old days the FAA limited use to 454grams total liftoff mass including motors. My Versions of the Grumpy Dog is 119.75" long BT-70/Bt-60 2 staged D12-0/D12-5 powered with 2 15" nylon chutes the Ewt. is 368grams Adding the two motors 452grams. It's Grumpy cause it doesn't like any wind at all. but flys really well.