up-dec7b.htm
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.
Drafted a log/log chart of distance, acceleration,
velocity, and time for reference. Wrote e-mails to some German
researchers
The NASA low cost conference was announced in the NASA CBD
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. 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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