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Downscaling the Estes Condor


The Fleet

Launch Log



While building my Estes Orbital Transport, I took a short side trip. The first stop was Jim Z's archive of rocket plans, looking for other piggy back glider. There were a number to choose from, but the one that caught my eye was the little Estes Condor, kit (#0807).

I like 13mm rockets. If you've spent any time on my main page you probably know that, among other things, I paint military miniatures. I guess I just like my models tiny.

So, I decided to take it one step further. The original Condor does, indeed, fly on 13mm motors. But, with a 55.4% downscale, I could create a version about nine inches long (glider about four inches long) with a minimum diameter (BT-5) body tube.

After some discussion on The Rockery Forum, I decided to downscale the size of all the pieces, but to leave the balsa thicknesses (i.e. 3/32" and 1/16") the same as on the original. I made photocopier reductions of the plans, and got to work cutting out balsa. Below is a photo gallery of the model in progress. She's nearly ready to fly now.

Hope you find this informative, and give this downscale a try yourself. I'll let you know how she flies.

The parts. That's a big pile of lumber. Also, I eventually used a toothpick for the under-chin spar on the glider instead of the dowel pictured. More on that later.
Getting ready to insert the engine block. I applied glue inside the BT-5 with the Q-tip, then slid the engine block in place with the used mini engine. I left 1/4" of the engine protruding to allow for taping the engine in later.
Engine block installed.
Shock cord installed. I'm just gluing the fairly porous sewing elastic directly to the inside of the tube. About one inch of the elastic is glued down, then the joint is coated with two more layers of glue over the top.
I decided to build the glider and booster side-by-side, so I could keep building while glue on one or the other dried. Here are the glider wings being glued together. Dihedral is added by sitting the tips on layers of napkin. The hobby knife laying on the joint provides a little weight on the joint.
Glider body with tail installed. If you have a sharp eye and a copy of the plans in front of you, you might notice that the nose is a bit big. That's to leave enough clearance under the chin to glue on the dowel for the glider/booster mount point. When I downscaled the plans, I kept the part thicknesses the same as in the full scale model. Therefore the notch for the canard is a bit deeper than it would be if strictly scaled down as well.
Dowel installed under the chin. More on this later.
Canard installed. I either cut the notch too long, or the canard isn't long enough (front to back). This came in handy later, when glide tests required more nose lift and I installed a longer canard.
Body tube marked for fins and lugs.
Wings installed on the glider. You can see the dihedral better in this shot.
Main fins installed on the booster.
Vertical stabilizers installed on the glider. It's supported nose down to allow the stabs to dry without drooping.
Booster vertical stabilizers installed.
Booster tip fins installed.
Modified glider. Toss tests of the original glider showed it to be very nose heavy. I tried sanding the nose down, but it wasn't nearly enough. Jim Z suggested replacing the dowel pin with one made from a toothpick. Doing that allowed me to sand the nose further as well, getting closer in shape to the original full size Condor's nose. At the same time, I replaced the canard with one that filled the oversized canard notch in the body. So, it's longer (nose to tail) than it ought to be.
Here's a better view of the new canard. This larger canard helped, but I had to sand an airfoil into it, AND put some decalage into the main wing by sanding the trailing edge into sort of an upside-down airfoil. That did the trick. At least for a toss test. I'll bring sandpaper with me the first launch. If it still nose dives, I'll complete the upside-down airfoiling of the main wing by rounding over the leading edge. If THAT doesn't work...I dunno yet.
Dorsal mount point on the booster. This is a slice of tubing from a plastic-handled Q-tip. It's just the right size to take the toothpick under the nose of the glider. I sanded the surface to get a better glue joint, sanded the standoff pylon's top surface to match the curve of the tube, and glued it all together with thin CA. I put a coat of Carpenter's (yellow) glue over that when I did the fillets. I may use thin CA to laminate a layer of paper over the tube and down both side of the pylon as well.
PNC tied to the loose end of the shock cord, secured with a drop of yellow glue. I made the shock cord twice the length of the body tube. I plan to make a six inch parachute from a dry cleaner's bag, then attach that to the nose cone with a #2 snap swivel.
Ventral launch lugs on the booster. These need fillets, but then this bird will be ready for a test flight. I'll try it out once or twice before I put the time into sanding and painting. If I can get the glider to fly, I'll be ordering downscaled decals from Jim Z.

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Page last updated: September 4, 2003
Copyright ©2003, William Scarvie

Any advertisements below are placed there by Angelfire, not by me. Companies or links advertised below do not imply my endorsement of these places. For the places I like to visit, please see my Links or Rocketry Links pages.