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Scratch build Pterosaur

Old 06-19-2024, 02:41 PM
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Default Scratch build Pterosaur

I'm working on the preliminary design of a 5 foot span scale model of the small morph of the azdharchid pterosaur, Quetzalcoatlus.
Aspect ratio is about 16.5, and design weight is about 29 ounces.
The animals were flap-gliders, and a juvenile about the size of this model would flap at about 3.5 Hz when flapping.
Wing membranes are viscoelastic and tension battened. Length of the head and neck is about the same as the wing semispan. Neck mobility is limited by hard stops in the vertebrae.
Primary pitch control is wing sweep. The tail complex (consisting of the hindlimbs, biological tail, and a membrane flight surface called the uropatagium) has about a third the surface area of the wings, and due to pelvic muscle alignments and attachments is incapable of creating a download. Consequently the 'replica' will be very unstable in flight. I expect it to crash a lot. A LOT. 😀

First step is to generate a sculpture of the head and musculature that I can use as a plug to vacuum form the hollow shells for the head, torso, and legs (these critters were muscled like Arnold Schwarzenegger on steroids). I'm thinking about repurposing old plastic milk jugs for that.

Biggest problem I see at the moment (aside from lack of stability) is the tiny size of the torso relative to the head and neck. It's gonna be hard to find room (volume) for the servos, battery, etc.

Wish me luck....
And I would welcome comments.

Last edited by JimCunn; 06-19-2024 at 02:47 PM.
Old 06-20-2024, 10:04 AM
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Not really a comment, but maybe an encouragement: long ago someone built a similar, but non-flapping model, here. Maybe some interesting considerations there about the head.
Old 06-20-2024, 10:59 AM
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I'm familiar with it. It is a stand-off approximate scale imitation of Pteranodon sternbergi.
For example, the foot on that model looks nothing like an actual Pteranodon foot. And the tension battening in the illustration is oriented incorrectly. However, the model is impressive in its own right.
I'm doing a 1/3 scale model of the small morph of the azdharchid Quetzalcoatlus. Due to the extremely long rather inflexible azdarchid neck, Quetz had a very small headcrest (which is preserved on two specimens)

Last edited by JimCunn; 06-20-2024 at 11:03 AM.
Old 06-20-2024, 03:20 PM
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I think what I'm most interested in at this website is information available about rc equipment and efficient use of ithe limited interior volume of the 5 foot span model.

I know how azdharchid pterosaurs generated flight forces, and the animals' physical responses to those forces - but I know very little about rc equipment or flying rc devices. I would expect to need to find an experienced rc pilot to fly the model for me, and the problem there is that the animals don't generate command authority in a manner that rc pilots would be used to.

Many of the model building techniques will also be new to me. My experience there is limited to designing and building fiberglass fairings for full sized aircraft.

I'm pretty much clueless about the number of channels I will need, what brand of radio, servos, etc.

Battery size is also going to be a problem. The animals flew as flap-gliders - they were a bit better at soaring than Albatrosses and Frigate Birds and were far more powerful flappers than birds (though they could only flap continuously for very short durations on the loose order of a minute or two). But the model isn't going to fly nearly as well, and will be much draggier, so power storage will be a major issue. There ain't much room for batteries.

Last edited by JimCunn; 06-21-2024 at 03:39 AM.

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