up-dec7b.htm Small-Pogo Project


Small-Pogo Project


Status Updates


December 14-20, 1997

December 14, 1997

I've been very busy with Christmas shopping and etc. The Small-Pogo project has been through a couple of updates.

I've spoken with a couple of folks who are modelers. One is quite willing to build the model but estimates two years. I've come up with a simple design that can be built in a couple of weeks, though fully controllable operation may take another few weeks.

My (very) preliminary design is to mount the motor inside a lightweight tube (about 10 inches across, the width of the propeller blade), another tube through the center (about 5 inches across) that is cut out for the engine, four balsa wood sheets mounted radially between the inner and outer tubes, and thrust vanes at the bottom. The controls, fuel, and etc would be inside the inner tube. The attached graphic shows a side view and an x-ray view from the top.

There is a place in Victorville (about 1 hr drive) that has 31cc Ryobi engines on sale for $149 (regular $169). During the holidays I'll probably go buy a couple of those, one for flying and one for a spare. Future uses include a flying windtunnel to test pulsejet and ramjet designs. Two of those engines on a lightweight platform should do about 250 mph. I'm going to send that small weedeater motor a friend gave me out to be modified for experimenting. My neighbor is going to give (or sell) me a two-cycle motorcycle carburetor and reedvalve assembly for pulsejet and ramjet testing. I checked the local mower shop and the leafblower fans are directly connected to the motors. This means that they spin at about 8,000 rpm and have tip speeds similar to those of the small jet engines. I'm still trying to obtain one of these compressors.

There is a low cost small payload launcher conference that is being sponsored by NASA's Marshall Space Flight Center (MSFC). The conference will be held at MSFC on January 13-14, 1998. While I would like to attend the cost may be prohibitive.
See http://stp.msfc.nasa.gov/stpweb/astp/conf.form.html

I've acquired a small workbench (my garage is too cluttered) and an air compressor (a Christmas present from my daughter). This should make jet engine experimenting easier (as well as inflating the tires on my car).

The January, 1998, issue of "Popular Science" has an article on Micro Air Vehicles (MAVs). Several concepts are shown with the first being the size of a small model airplane capable of transmitting video images to the ground. Another uses a micro GPS receiver. I didn't have time to read it all at the library but will buy the magazine, possibly today.

I found the following in the amateur rocket newsgroup. From the web site it looks like cameras, transmitters (nearly unlimited line of sight), and receivers are currently available.


"There is a 900 mhz LICENSE FREE transmitter & receiver, includes the camera on sale at Staples. Runs about $300. Not bad really.
If you are interested in a do it your self type of deal, check out Ramseye Electronics". the rudders.

They sell color cameras as well as the black & white one you guys are looking at.

December 15,1997

Drafted a log/log chart of distance, acceleration, velocity, and time for reference. Wrote e-mails to some German researchers who are interested in using ramjets, scramjets, and hybrids for low cost access to space. Also wrote to the author of a 1989 paper on testing of ramjets. I'm looking for info on ramjets that can be operated at both low speeds and high speeds.

The NASA low cost conference was announced in the NASA CBD . It will be an on-site comuter-based interactive conference (whatever that is). I found MSFC's low cost page and all it talks about is how to build the same old engines cheaper, though this may be something different.

No news on finding anyone to build the Small-Pogo for me in any reasonable time frame. It looks like I'll probably do it myself, hopefully with helpful suggestions from friends. If nothing breaks loose in the meantime I'll pick up an engine or two, avionics, raw materials, and etc and get started.

Came up with some nifty ideas of using ramjets for launch assist. With a 1300 ft tube (about the height of the Chicago Sears Tower, see "Scientific American," Dec 97) and 10 g acceleration (55 psi air pressure) I can get a launch vehicle up to Mach 1.5 easily starting a ramjet. Will put more into Low-Tech Ways to Start a Ramjet.

December 20,1997

Still working on the log/log plot. Been sick for two days so didn't get much done. Picked up a leafblower compressor for $10 US. It's 8 inches across and aluminum. I should be able to make an inlet shroud and diffuser out of wood. I have some bar-stock I can make a shaft out of. The combustion chamber is going to be a trick.

Been working in the garage a little. I've learned the necessity of a flame holder. Now to work on a more efficient one. I cannibalized my kerosene space heater for the constant spark source and dug up an old hairdryer for an airblower until I can get a leafblower for my low-speed (100-150 mph) wind tunnel.

I checked out the local hardware store for PVC tubing. They have some 4 inch, 240 psi stuff. With 100 psi I should be able to get be able to get over 1200 lbs of force behind a projectile. Talk about your super-potato gun. I should be able to get some bigger stuff from a commercial outfit.

No word from anyone on model airplane stuff. I'll probably start buying parts right after Christmas and take my chances.



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