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Old 10-22-2019, 01:40 PM
aeppel_cpm aeppel_cpm is offline
Ciderwright
 
Join Date: Apr 2013
Location: Burlington, WI
Posts: 532
Default Modeling a Terrier Malemute

I've been thinking of doing a Terrier Malemute for my next sounding rocket. Partly because the Malemute, with the 3:1 ogive nosecone reminds me of a PSII Leviathan (which I have parts for) and partly because I want to name it 'Double Dog Dare'.

Massless Dave (particles with rest mass can't go the speed of light, so EZ2C becomes massless)
has posted lots of great Terrier material, both here and on the Forum That Shall Not Be Named. I think YORF has more scale people, so I'm forking the Ute thread so MarkB can get back to posting Tomahawk variant pictures. Which I'm looking forward to.

I've spent some time holding a micrometer against the computer screen and taking measurements.

Here's the problem I've run into. Terriers, like Nikes, seem to have flown with a number of different fins. And it looks like even with Nike fins sometimes.

Peter Always' drawing of the Terrier Malemute show it in a configuration that seems to appear just once - the first flight. He shows the 3:1 ogive (when seems to get some use, based on other photos). A payload section about 2.5 calibers long - which is the shortest pictured. Other Terrier Malemute and Terrier Improved Malemute (motor 2" longer and improved attachment to the interstage) show payloads 6-8 calibers long. No biggee if I want to model model more than one - just more body tube.

Peter's drawing shows the double wedge profile with a root : tip cord ratio of 3.8, a span of 22.1 inches and a root chord of 24.5 inches. That's clearly the same fins on the RIM-2F and he has the same measurements in the Homing Terrier Refit RIM-2F drawing.
Dave has posted another Terrier fin drawing with a diamond profile, root:tip ratio of 2.5, root chord of 33.5", span of 22 inches. With matching photos. I believe it to be the RIM-2C/BT-3 version.
Going through photos of the Terrier Malemute, I'm measuring root:tip ratios of 2.13. multiple photos with different payloads. And a root:span ratio of 1.2 - measurably different than the 1.1 of the 2F, or the 1.5 of the 2C.

So what the heck fin is it? And how's a modeler to choose?

And thank you for the photos, Dave. Even of I end up redoing my CAD model before I print it, the photos have some nice bolt niche and panel details that the drawings don't.

(also @PeterAlway - thanks for many fine drawings)

Edit: The Malemute development paper shows the short payload and the Terrier 'F' style fins.

(This did get posted over on TORF because YORF blacked out in the middle of typing this.)

I've since found that the Nike Orion fins seems to be a good fit, root:tip, though I'm still working on the span.
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