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-   -   Apogee SR-72 Darkbird (http://www.oldrocketforum.com/showthread.php?t=16271)

GlenP 10-12-2016 10:53 PM

Apogee SR-72 Darkbird
 
2 Attachment(s)
This mini-engine powered rear-eject streamer/glider is not your father's Centuri Magnum-D SR-71 Blackbird from 1981, but the Apogee SR-72 Darkbird seems like it will be a fun small-field flier. May be a while before I have the weather conducive to launching this one. A fun weekend build, nice lines.

I made one small modification, the little boat-tails for nozzles on the engine tubes, cardstock transtions printed from PayloadBay.Com templates, adds a nice touch.

PaulK 10-23-2016 08:32 AM

Nice work, I look forward to flight reports! I had a hard time getting a good glide from mine, but it is a good looking glider.

GlenP 10-23-2016 06:29 PM

Thanks! Going to be the rainy season around here for a while, the yard is too wet to make test glides in the grass. The instructions show where the c.g. should be so you can add the right amount of nose clay. Then you have to adjust the balsa stops to get the flap angle right by sanding them down a little at a time and making test glides. The approach to tuning the glide is somewhat similar to the Dr. Zooch Shuttle glider, I was able to get a good glide from that one. Depends on if you build it too heavy, extra weight will kill the glide performance. You can still get it to glide, but it might be more like falling with style than gliding.

I remember the Centuri kit would deploy two large chutes with the main body suspended horizontally in a higher drag configuration so it appeared to be gliding like the SR-71 coming in for a landing. Mine caught a thermal perhaps and just kept on gliding beyond the field out of sight to join most of the rest of my childhood rocket collection, which I keep scattered in the treetops around the soccer fields in my hometown.


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