Pterosaur

aerostadt · Aug 8, 2015

I bought the Pterosaur by Kopter Rockets, which was started by by Walter Senoski back in the early 1970's in the Pittsburgh area. There is an article in the March/April 2015 Sport Rocketry magazine. I actually flew at rocket meets in the early 1970's where Walter was flying his Kopter Rockets with the helicopter recovery.

The Pterosaur is a rocket glider that uses an internal piston to activate the elevons and has no ejecting parts, pop-pods, etc. The kit comes with 4 pages of detailed figures and instructions and all parts. There is also a pattern guide available.

aerostadt · Aug 10, 2015

The Pterosaur uses a small slit between the motor mount tube and the piston tube to pass ejection charge gases to the piston. The two tubes are glued together and at the same time the small slit is sealed with glue externally. The kit comes with all the balsa pieces pre-cut for the wing and rudder, but it is a jigsaw puzzle to figure out how they go together. The pre-cut wing piece A has a slightly different shape than the drawings. The wing pieces can be pinned to a board with wax paper underneath and glued into place.

aerostadt · Aug 18, 2015

The Pterosaur is close to completion. I will add the rubber band for lifting the elevons after a light coating of paint. The wings are thin 1/8" balsa, but I do not plan on papering them or anything, because of weight considerations. I was missing one balsa bulkhead, but I ordered a new one from Balsa Machine Services. The photo's show how the piston activates the elevon release.

J Blatz · Aug 19, 2015

Aerostadt-

I dig it man! Nice build.

I bought one of these as well as the smaller version and can't wait to build and fly them.

KenECoyote · Aug 19, 2015

That is truly awesome! I remember reading that article in Sport Rocketry and was really envious of anyone who got those kits. Thanks for sharing this treasure and wish you nothing but good mojo for the Pterosaur!

aerostadt · Aug 19, 2015

Aerostadt-

I dig it man! Nice build.

I bought one of these as well as the smaller version and can't wait to build and fly them.

That is truly awesome! I remember reading that article in Sport Rocketry and was really envious of anyone who got those kits. Thanks for sharing this treasure and wish you nothing but good mojo for the Pterosaur!

Thanks, J and Ken. I have painted the Pterosaur and installed the rubber band. I still need to balance the model and trim for flight. I am planning on flying this Fall at a club launch.

aerostadt · Oct 17, 2015

I had two good flights today with the Pterosaur both on D12-3. The c.g. as measured was about one inch forward of the location called out by the instructions. I decided to cut 3" off of the long tube. This brought the c.g. back, but still not enough. The backyard test flights showed a little bit of stall. I decided to go with the slight stall. I figured that this would guarantee that the model would transition to a glide rather than a dive. Winds were about 5 to 10 mph. The first flight was straight up. Perhaps, the wind was low. The second flight looks like some wind cock in the photo.

BTW I launched the Mega Red Baron today on an E20-4 and it had a good flight, but blew off the nose cone when the motor was ejected.

cameraflyer · Jan 23, 2019

Started to build my own Kopter Pterosaur. As noted by aerostadt the plans call for a complicated jigsaw puzzle to construct the wing. So I cut out the pieces in posterboard and fitted them together. From that I got a triangle shape of 21 5/8 in. wide at the base by 13 3/4 in. high. See attached photo. I glued 6 in. wide 1/8 in. balsa sheets together and cut out the triangle. That just left a small cut at each wing tip (3/4 in on leading edge of wing tip by 1 1/4 in. from the training edge. And the work goes on.

aerostadt · Jan 23, 2019

Good Luck! Let us know how you do. This rocket glider works pretty good. I looked at the people who flew it on Rocket Reviews and I don't think that anyone had a failure. Perhaps, you can do a better job of balancing for gliding than I did. I tended to have stalls.

cameraflyer · Jan 25, 2019

Thanks for the encouragement. I'll keep posting my progress. Walter Senoski's design is excellent though some parts I'll have to improvise as they are hard to get now. Kind of neat to look at his original 1975 patent https://www.freepatentsonline.com/3888178.pdf. He put a lot of thought into this design.

cameraflyer · Jan 30, 2019

Aerostadt (or anyone else) - Work on the Pterosaur is progressing well but I had a thought. The only thing I saw in the construction that might allow the Pterosaur to spiral back is to taper one side of the rear of the rudder. Not wanting to chase a rocket (assuming all goes well), I wonder if that is enough to keep the Pterosaur from gliding away?

aerostadt · Jan 30, 2019

Cameraflyer, I would say that my Pterosaur did not glide well enough that I had to worry about it gliding away. The glide would tend to be stalls and flat falls, but I had plenty of flying space here on the Utah prairies. I think I only launched it two times, but I never had any concern that it would go into a steep glide and crash. Feeling that good about it, I gave it away at club auction this past summer. There are a number of flights recorded on Rocket Reviews with no crashes. In fact one of the modelers cloned it like you.

I tend to think better balancing might make it glide better. I might have glued the nose in prematurely and lost that option. There is also the matter of having a good balance for the boost phase.

cameraflyer · Jan 31, 2019

Aerostadt, Thanks for the input. I'll have a look at those reviews. I'm in eastern Ontario so not that many big flat fields - a lot like northern New York - hills and forest and farmland (that the farmers don't like being trampled). The weather being what it is I doubt I'll even be able to get to balancing it for months yet.

kuririn · Jan 31, 2019

For those that have not been lucky enough to score a kit, there are plans and templates here:
https://www.oldrocketplans.com/kopter/kop_RK15/kop_RK15.htm

Rktman · Feb 3, 2019

cameraflyer said:
Thanks for the encouragement. I'll keep posting my progress. Walter Senoski's design is excellent though some parts I'll have to improvise as they are hard to get now. Kind of neat to look at his original 1975 patent https://www.freepatentsonline.com/3888178.pdf. He put a lot of thought into this design.

This thread and you're clone have got me interested in building my own Pterosaur. Couldn't locate the templates anywhere, would you be willing to post templates and list what clone parts you're using for things like the nose cones, blowout plug, etc.?

kuririn · Feb 3, 2019

Rktman said:
This thread and you're clone have got me interested in building my own Pterosaur. Couldn't locate the templates anywhere, would you be willing to post templates and list what clone parts you're using for things like the nose cones, blowout plug, etc.?

See the post before yours.

Rktman · Feb 3, 2019

kuririn said:
See the post before yours.

Oop...that'll teach me not to read everything. Thanks Kuririn.

cameraflyer · Feb 4, 2019

Rktman, You can get many of the Estes parts the are no longer available from Estes at erockets.biz (see attached screen capture). I used the Semroc NC-55 for the larger tube. I already had the Estes BT-50 nose cone pack which includes a plastic one that is similar to the one in the parts list so I used that. The Semroc coupler NB-55 is only 1 1/2 inches long so I did not use that in this construction. I used a Estes BT-55 a tube coupler and plugged it with a circle of balsa as a tube coupler/block.
I used some spare parts to create the blowout plug. If I had to do it again I would do the blowout plug as follows: Start with a 2 1/4 inch piece of BT-50; plug one end with a circle of balsa; use BT-50 to BT-55 centering rings along the plugged end of the BT-50 tube to cover 1 inch of the tube. ; use BT-50 to BT-55 centering rings along the other (rear) end of the BT-50 tube to cover 1/2 inch of the tube.
Rather than use a 1/8 inch retainer ring in the BT-55 I decided to attached a portion of an engine hook on the outside of the BT-55. I glued it so that I could lift the hook enough to easily install and remove the ejection plug.
If you do use a retainer ring you will have to sand the 1/2 inch of rear centering rings enough so they can fit through the retainer ring.
With the above arrangement you just sand the sides of the rear centering rings down to the BT-50 tube. To give a little stand-off room I glued a 1/2 inch x 3/4 inch piece of 3/32 inch balsa to each sanded side. I glued the elevator hold-downs to these. See attached photos.

Rktman · Feb 4, 2019

cameraflyer said:
Rktman, You can get many of the Estes parts the are no longer available from Estes at erockets.biz (see attached screen capture). I used the Semroc NC-55 for the larger tube. I already had the Estes BT-50 nose cone pack which includes a plastic one that is similar to the one in the parts list so I used that. The Semroc coupler NB-55 is only 1 1/2 inches long so I did not use that in this construction. I used a Estes BT-55 a tube coupler and plugged it with a circle of balsa as a tube coupler/block.
I used some spare parts to create the blowout plug. If I had to do it again I would do the blowout plug as follows: Start with a 2 1/4 inch piece of BT-50; plug one end with a circle of balsa; use BT-50 to BT-55 centering rings along the plugged end of the BT-50 tube to cover 1 inch of the tube. ; use BT-50 to BT-55 centering rings along the other (rear) end of the BT-50 tube to cover 1/2 inch of the tube.
Rather than use a 1/8 inch retainer ring in the BT-55 I decided to attached a portion of an engine hook on the outside of the BT-55. I glued it so that I could lift the hook enough to easily install and remove the ejection plug.
If you do use a retainer ring you will have to sand the 1/2 inch of rear centering rings enough so they can fit through the retainer ring.
With the above arrangement you just sand the sides of the rear centering rings down to the BT-50 tube. To give a little stand-off room I glued a 1/2 inch x 3/4 inch piece of 3/32 inch balsa to each sanded side. I glued the elevator hold-downs to these. See attached photos.

Thanks for the info and tips, they really help. Appreciate it!

cameraflyer · Feb 5, 2019

Oops I wrote phoenix instead of Pterosaur.

cameraflyer · Feb 5, 2019

Almost finished my Kopter Pterosaur. All I have to do now is balance it, paint it, etc.. etc

..

aerostadt · Feb 5, 2019

CF, your model looks good!

Rktman · Feb 6, 2019

Nice job, it's looking great!

Pterosaur

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