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Old May 18, 2015, 06:13 PM
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Build Log
Airfoil Foam Blades

This is how we made high performance autogyro blades from DollarBoard foam, Tyvek, and carbon rod. These blades have some distinct advantages over traditional wood blades. They are fast and easy to make, very low cost, eliminate the need for a complex hub design because the blades flex, so we don't need hinges. They also survive crashes and tip-overs well because they flex instead of breaking.

An overview of how a blade is made: We start with 2 cut pieces of foam, 18 inches long by 2-1/2 inches wide. Remove the paper on both sides on one piece, and one side of the other. Spray adhesive applied sparingly is used to glue the 2 pieces together. This blade blank is then affixed with straight pins to a wooden jig that has preformed airfoil shaped wooden structures attached to it at each end. A simple cutting bow made from part of a yardstick is then used to cut the airfoil shape into the blank. It takes about 1 minute to load the blank into the jig and cut it.

After cutting, we take a minute to remove the foam where the tip weight goes, then use hot glue to secure it. A bit of the spray adhesive is then used to attach a 2mm carbon rod to the leading edge of the foam, which still has the paper attached on the bottom. Again using spray adhesive, the foam and attached carbon rod are glued to a piece of Tyvek cut to 18-1/4" long by 6" wide. Creases in the Tyvek are then made at the trailing edge, and also in the remaining width that folds around the leading edge.

Once the creases are made, we give the Tyvek a good spraying with adhesive and place the blade on the building board, rolling the foam into the Tyvek until it is attached to the foam core. A plastic gift card is then used with plenty of pressure to smooth down the Tyvek covering. The last step is to fold the Tyvek at the place it extends beyond the blade tip by 1/4", first the bottom, then add a little CA glue, and then the top.

When done, the blades are cut to the desired length and then glued with CA adhesive to plywood "Tangs" . Each tang has a hole in the end and the tangs bolt to a round, 1/4" thick plywood hub.
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Old May 18, 2015, 06:45 PM
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Greetings Rus...looks like you have come up with a good idea.....I think that I would have to purchase a pair of disposable coveralls to get my hands on Tyvek
Happy Landings...
Chris...
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Last edited by britinoz; May 18, 2015 at 07:02 PM.
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Old May 18, 2015, 07:59 PM
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Tyvek

Chris,
Here in the USA, the postal service has Tyvek envelopes available for free. Perhaps you can request a mailing from here, then use the envelope to make your blades?

One envelope is large enough to make 3 blades.

Our Home Depot Home Improvement stores carry rolls of Tyvek, so maybe you can find some locally? Builders use the stuff to wrap entire houses!

Good luck!

Russ
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Old May 18, 2015, 08:08 PM
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Into The Wind kite store sells plain, white Tyvek by the yard:
http://intothewind.com/shop/Repair_a...e_repair/Tyvek
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Old May 19, 2015, 04:22 AM
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Thanks for the info ...I do like your blades...I shall to do a bit of a search ..........
Chris...
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Old May 19, 2015, 12:58 PM
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Cutting the blade

Here is a short video showing how we cut the blade from a foam blank:

Autogyro Blade Cutting (1 min 11 sec)
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Old May 19, 2015, 01:30 PM
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Testing the new blades

We designed and built a simple a test platform for the new airfoil foam blades. The blades performed so well, and the test platform (now named Mr. Tester) was so simple, easy to make, and durable, that we have had dozens of hours of stick time on this setup, which includes crashes, tip-overs, and other mishaps. This unedited video was shot showing that after all this, Mr. Tester still flies well on the original blade set.

There are touch and go's, ...slow flying,..quick climbs, two motor- off autorotation landings, as well as a sudden high winds condition due to a passing thermal which didn't bother Mr. Tester. Hope you enjoy the video.

Flying the airfoil foam blades (6 min 5 sec)
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Old May 19, 2015, 07:39 PM
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Now that looks like one fine fun machine. Great video of your blade construction. Thanks for the info and the post.
Happy Landings
Chris...
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Old May 23, 2015, 12:55 AM
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Hey russ,
Been watching you guy's test fly when it was too windy for me to fly my foamies.
great flying by kyle,it looks like in the right conditions, a full size auto gyro could be powered by pedal power connected to a "grabby" prop.

great job!!
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Old May 23, 2015, 10:54 AM
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Windy? Who cares?

Thanks Cutter,

Kyle has a habit of flying small electric models in front of his house on a quiet residential street. We have noticed huge effects on these traditional fixed wing airplanes when flying there due to rotor from the houses, and gusts coming across open vacant lots. It has really made landing the models very difficult and unpredictable.

Well, along comes Mr. Tester who just doesn't care if it is windy, or if there is rotor, or if there are gusts...he just flies along as if all is well and lands and takes off from Kyle's short driveway. No problem! The only hazard is a gust-induced tip-over once on the ground. We used to worry about that, because it would break a wooden blade, but now, even that is no threat. The foam blades just bend! No halting the fun for repairs! Glad you enjoyed the flying video!
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Old May 24, 2015, 11:41 AM
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Rus, is your Mr Tester rudder/elevator or live head? It realy seems remarkably stable in the wind...

About "TYVEK"... The only Tyvek that seems to be available here is safety clothing... from their website:

"DuPontôTyvekģ is made of pure HDPE randomly laid to form a substrate that combines the performance of paper, film and fabric...."

Does that sound about right?

George
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Old May 24, 2015, 01:17 PM
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Tyvek and Rotor Head

Hi Georgy,
Tyvek is exactly what you posted. It is really a combination of paper and polyester fibers. Here in the US, it is very commonly available for mailing and shipping use, with many carriers using it for envelopes. It is water repellent, but accepts CA thin glue very readily to make an exceptionally strong bond. You could try using paper instead, it might work?

The control head is dual control (DC). It tilts left and right, as well as forward and back. It is fairly easy to construct. We do use rudder and a fixed horizontal stabilizer. The rudder isn't used often, but sometimes it really helps. Oh, and our very first Mr. Tester did have rudder and elevator with a simpler control head that only tilts left and right. If set up this way, the tail boom is much longer putting the vertical fin just beyond the reach of the blades It worked fine, and we even think it would be very good for beginner autogyro pilots, as it is a bit more stable and visible in the air.

Hope that helps!
Russ
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