The first flights shown at the video link above had a slight tailwind and appeared to go much higher and landed much farther away than the second set of flights which had a slight headwind (the launch rod was angled away from the launch area). However, in the second set of flights the 4-blade version actually auto-rotated upon descent, unlike in the first set of tests.

Anyway, I'm going to try some additional 13mm powered spinners, all single motor powered, to see how they perform. Single engines reduce potential ignition issues and extend the number of flights using a single 4-motor 13mm motor pack to four.

One is a smaller diameter bladed version and two with Kline-Fogleman airfoils, one a KFm-2 with one 50% chord step, the other a KFm-3 with two steps, one at 50%, the next at 75%.

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"Walter, WHY is there an EAR in the omelet?" - Peter Bishop, Fringe, S01E16

The 18mm, 24mm, and 29mm versions using 2 step KF airfoils fly great:

https://www.rocketarium.com/Rockets/Vortico
https://www.rocketarium.com/Rockets/Mega-Vortico
https://www.rocketarium.com/Rockets/Turbo-Vortico

Landing is rough on them if they hit a hard surface.

__________________
Paul
If we weren't all crazy, we would go insane - Jimmy Buffett
NAR #87246 www.wooshrocketry.org

Mine did, too, and since they are so light (25% infill which is only slightly less strong than the much heavier 50% infill) they have no problem with hard surfaces and spin nicely on the way down. I couldn't compare the type 2 and 3 KFms because, incredibly, I had a blowout CATO on a 13mm motor! Blew the top right off of the spinner! Only an empty motor case remained.

That's definitely a first for me, but something always seems to screw up my experiments due to Estes motor issues. A base drag experiment vehicle with 3D printed, changeable base discs nosed in on its first launch when an Estes motor ejection charge did not fire AT ALL. Destroyed the vehicle and an altimeter. A club member on the same day as my recent 13mm issue was burning D12s in spools and doing static tests because he's also had ejection charge problems - one not firing AT ALL. After my base drag vehicle's destruction, I did static tests of many different lots I have and only ONE motor had what I'd call a properly energetic ejection charge. I've also seen ejection charge issues at mass STEM launches. When I was a kid and fired a bazillion Estes and Centuri motors, I don't recall any ejection charge issues.

Anyway, because the KFm2 version that didn't have a CATO spun so rapidly during descent, for safety reasons I've printed new versions with a protective ring. I've printed the original diameter with three blades rather than four to decrease the unnecessarily high (and extremely draggy) spin rate on ascent and two smaller sizes, each in KFm 2 and 3 versions. Whichever one has the most interesting flight characteristics will be the one I'll stick with.

Largest and smallest diameters shown.

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__________________
"Walter, WHY is there an EAR in the omelet?" - Peter Bishop, Fringe, S01E16

As a long delayed update to this, the three blade KFm3 variant has the best performance, but due to a too-limited variety and hobby store availability of the preferable 13mm motors, I've upscaled and have already printed an 18mm version now awaiting launch with good weather and no fire bans at the next monthly launch.

__________________
"Walter, WHY is there an EAR in the omelet?" - Peter Bishop, Fringe, S01E16