up-jan8c.htm
Continued to work on the Small-Pogo. There was more detail work than I had thought (plus this is a part-time project). I've completed cutting out most of the parts for the lower body tube and have begun assembly. By tomorrow I hope to complete the lower body tube and attach the vanes and engine mount. The vanes will be butt-glued between the lower body tube and the shroud. They will be filleted with balsa at the body tube and possibly at the shroud, depending on the stiffness of the shroud (a.k.a. cowling). If the shroud seems too flexible I'll have to find a way to stiffen it. Possibilities are a) laminating balsa sheets inside the shroud between the vanes. b) fiberglassing the shroud, and c) adding additional vanes. The latter has the appeal of improving the directionality of the flow
Completed the lower body tube, mounted and gusseted the vanes on the inside, and got superglue all over my fingers. It looks like the lower body structure will weigh about 7 oz. The engine and propeller weigh about 20 oz. All together the Small-Pogo will probably weigh about 4 lbs. The YS 0.60 engine should be able to lift this straight up with ease. Tomorrow I hope to add the shroud and get in some shopping.
I've made a major design decision. The top of the upper body tube will be flat with four to eight bolt holes. The upper stages and inter-stage assemblies will be independent units that bolt to the upper body tube. This will allow quick configuration changes for different upper stages. The bottom of the lower body tube will also be fitted with bolt holes so that the landing strut assembly can be built independently, and changed out if necessary.
Progress has been slow due to a side issue. I had to develop the capability to consistently drill pattern holes in bulkheads to facilitate modularization. This completed I'm back to assembling the Small-Pogo. The shroud is attached and the first shroud upper-half has been cut. I've decided to make a parachute a major part of the design. With one engine and no glide-back capability it would be disastrous to not have a good parachute.