up-feb9.htm Small-Pogo Project


Small-Pogo Project


Status Updates


February, 1999

My last update was June 18, 1998 and, at that time, I was trying to get the thrust up enough to fly the vehicle. Well, it's been 8 months and a couple folks have asked for the rest of the story. So, I'll try to wrap this up.

The short answer is I was unsuccessful. I completed the engine test stand and measured the thrust accurately enough to know that it was insufficient, as in about 5.5 lbf thrust/5.5 lbm vehicle. The best I could get was about 6 lbf with the best blade (I tried many) and the hottest tune. This left no room for any variation in fuel flow, air flow, and etc.

Failure Analysis: Human error. During early engine tests I had the engine mounted on a 2x4 framework. At full throttle, hand held, this felt (qualitatively) like it was trying to lift-off. I weighed the engine/mount at 7.5 lbm. This was the basis for my thrust prediction. Since it agreed with what the salesperson told me about the engine and my own desires I failed to properly verify the thrust.

But this is only part of the story. At the same time I was starting to work with a friend who wanted to use the concept on a much larger scale. The Small-Pogo was to be the test bed for some of the flight dynamics and avionics testing. My friend asked me to withold further progress reports for commercial competition purposes. This is why the reports suddenly stopped without explanation.

Over the next several months I spent much of my time on the friend's project, which eventually changed direction and so no longer needed the Small-Pogo. Another friend decided he wanted to build a micro-turbine engine based on the Schreckling design and I had most of the power tools to do it. So I was also working on that project when I could. Then I hit on the idea of the Tri-Mode launch concept and started studying and writing about it. These were some exciting months, but very tiring.

The first friend's project is proceeding, basically, without me. The second friend is off on a 3-4 month business trip to Albuquerque so his project is on hold. Most of my free time now goes to developing amateur ramjets, though my reports are not so prolific.

The Small-Pogo is not dead. It currently hangs in my garage and all the materials I've accumulated are in boxes. Some day I hope to get back to it and make it fly. A month ago I bought a Ryobi 31cc weed wacker from Harbor Freight for $45 with the idea that I would convert it to a model airplane engine for Small-Pogo II. I've been doing some additional reading and thinking and realize that there will also have to be a major redesign. This time, though, I will quantitatively test everything.

A final note, as if any of my projects are ever really final. The goal I was trying to achieve when I started the Pogo study was cheap space launch. The Small-Pogo was to be a low-cost demonstrator for an airbreathing first stage. Later demonstrators would have used turbojet engines and, at best, achieved Mach 2.5. Mach 5 could have been achieved with the addition of ramjets. The Tri-Mode was a refinement, or side step, to get to Mach 5 without the expense of the turbojets. The Amateur Rocket Launch Assist (ARLA) project is a low-cost demonstrator of this concept. So, from a high level perspective, I'm still on the same path I started a long time ago.

Thank you all for your interest and patience.



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