"PRE-ROTATION"   Page one.

Is it an art...  an acquired skill...  or just luck?

Pre-rotation is the pre-spin of a rotor to initiate entry into autorotation, without which an autogyro will not/cannot fly.    We occasionally hear about a gyro modeler,  so desperate to get his rotor "pre-rotated" that he resorts to a bit of foolishness...

The most recent incident, forwarded to us by Rick Anderson, involves (name deleted to save embarrassment), who had busted the rotor blades of his Cabezas "DC Gyro"...   After building new ones, he decided to fly the newly bladed model.    Good idea?  yes.    It was a zero wind day.    Good idea?  no!

He couldn't get them to spin up...   Wanting desperately to fly the thing, he talked another guy into standing in the back of a pickup truck while holding the model, as the truck was accelerating to get the rotor to spin-up...    Good idea?  no!

Well anyway, off they drove and the blades spun-up quite well... Having briefed the holder to release the model when the rotor really started to spin up fast, which he did...   Unfortunately the flyer was so engrossed in watching the rotor spin up, he forgot all about throttling up the power...

The guy in the truck let go of it, as briefed...  The powerless model ballooned up and "splat"    The model landed rather hard,  but miraculously didn't break anything..   Well, the big decision was to do it all over again...  This time the flyer was sure he`d throttle up this time and off it would go into the wild blue yonder....

So they tried it once again...   This time the driver elected to drive a little faster to get it to spin up even quicker.   However.... the guy holding the model held on to it too long and the blades folded and broke from all the excessive rotor drag it produced....!!!!

So was all this effort a good idea?    No,  not really!

Now, here`s another duzzy!

Back a few years ago, a couple fellows in the Portland, Oregon, USA, area (who shall remain anonymous) decided to test a new rotor system and see how well it would spin-up and tilt the rotor.............




       After admiring his craftsmanship..............







This fellow convinced a friend to allow him to strap his model to the top of a pick-up truck.....










    As they began to drive slowly down the crowded street, he gave the rotor a slight pre-spin....









But alas', it refused to accelerate..........






     Having reached the end of the street, they decided to turn around and drive faster in the opposite direction.... And as they accelerated through 16 to 18 miles per hour, the rotor suddenly accelerated...  and cries to "slow down" could be heard to come from the flyer in the back with the model!







Probably in the neighborhood of 20 miles per hour, the entire rotor with pylon lifted and departed...







Fortunately no one was struck by the rotor, the truck had refused to lift,
and the parts were found along the side of the road.








Needless to say, the entire system was in need of repair.....





       OK guys.....   which one of us is going to take the blame for this?





 To the Tech page Back home  rev..8-22-99..jb