in this vid the helicopter flies upside down immidiatly but it dosnt crash it stays there!, i dont understand dont it have to change rotor directions to fly upside down?!






[link]http://www.lance.co.uk/clipsForRelease2004/dannySzaboFreestyleFinal.wmv[/link]

The pitch of the blades is changed to a negative angle, the rotor still turns the same direction.

Difference is the rotor is thrusting upward instead of down.

You just need negative blade pitch to fly inverted...

Yeah, he's probably confused. Most people that don't fly heli's have some pretty wild thoughts about how they work... I've seen a lot of people who think that ALL heli's are fixed pitch, and you'd be AMAZED at how many people actually think the whole head of the heli "tilts" to move fore/aft/right/left... Or if he does fly, he flies the micros which generally are all fixed pitch....

Anyway, exactly as was stated above. A "collective" pitch heli changes the pitch of the blades to provide lift. The "throttle" doesn't normally change the SPEED of the head, or RPM rather... By pitch, we mean the "angle of attack" the blades have... When you drive down the window and stick your hand out the window flat, what happens? If you keep if level, it does nothing... that's "0 degrees pitch"... If you tilt the front (leading edge) of your hand up, thats "positive pitch"... Tilt it down, and that's "negative pitch". Now if you flip you whole hand over, negative pitch becomes postiive pitch.. So helicopter no go boom... If it WERE a fixed pitch machine... that means the blades ALWAYS stay at one pitch.. Let's say 7 degrees positive pitch... To generate more or less lift, the RPM of the head is changed... spins faster, more lift, spins slower, less lift... In this case, if you flip it upside down... Helicopter go boom...

And in both cases... Helicopter go boom is always followed by "visa card comes out"....

Yup. That's the difference between crashing an airplane and crashing a heli. With the airplane you get out the CA, balsa wood and covering, with the heli you get out your VISA (or checkbook).



Mike

Yup .... agreed... My Hawk Sport was a good example of positive pitch going into a negative tree.... Opposites attract you know. That resulted in the Visa coming out in short order... LOL