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Old Oct 17, 2012, 09:38 AM
Ospreyman is offline
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Cheshunt, Hertfordshire
Joined Aug 2009
224 Posts
Minimum inspired 4 blade pre-rotate Autogyro

I have long been fascinated by autogyros and recently took the plunge and bought the HK Cierva C30, with more or less disastrous results. Undeterred, I followed this forum and came upon Jochen's Minimum. I built the minimum, using the HK C30 blades, and found instant success. Old Jochen sure knew how to design them, bless him.

I have been flying the minimum for a while now and thought it would be nice to have a pre rotate feature rather than doing the autogyro shuffle down the strip or risking it getting off too early and having it do the funky chicken on its side.

I am a great believer in sticking to what you know and making slight adjustments to it. That's why my 'creation' has a minimum tail section and HK blades, I know they work.

I also thought that 4 blades would give me more lift than three. Ok , so now I have a design brief . But, how to achieve it all?

the First step was to buy a 4 blade flybarless head from ebay for 20 and a basic HK450 heli from HK for 23

Bearing in mind that I wanted to use a 300W motor driving a 9X6 for propulsion the first job was to replace the way-too-short heli main shaft with one that would allow prop clearance. Then I turned the rotor drive gear over so that the sprag clutch worked the right way for the HK blade rotation.

Keeping the same angles as on the minimum I angled the entire heli frame backwards to give me 8 degs lean back on the shaft. Then built a frame to mount this lot onto a tricycle undercarriage ( just like the minimum), a basic cruciform for wheel positions and a CF tube out the back to mount the tail on.

Rather than me bang on let me know if this thread is of interest and I'll give a blow by blow account of the build

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