Why do helicopters "chop"?

Inspector507 · Mar 16, 2004

Re: Why do helicopters \"chop\"?

I've been in several..........one overlooking Niagra Falls, what an awesome view. I even got to ride in the original Bat Copter a few years ago.

MossRoad · Mar 16, 2004

Re: Why do helicopters \"chop\"?

 Vietnam-era Huey 

I can remember standing in my yard as an 7 or 8 year old in the fall of either 1968 or 69. We live in North Central Indiana. We heard this tremendous noise and from the East came several large goups of Hueys. It was normal to see groups of two or three, but these were groups of teens. And it went on all day. That happened several times, as I can recall. Found out later in life that it was probably pilot cross country training on their way to California. Then the helicopters were to be loaded on ships and sent to Vietnam for the war. That noise is something I will never forget. There must have been hundreds of them.

PineRidge · Mar 16, 2004

Re: Why do helicopters \"chop\"?

 The point is, that I was amazed at when you return to your starting point some 2 minutes later, you run smack dab into the busted up air (prop wash) you made when you started the manuever. A very noticible thump. Way cool.


Dap even better than prop wash is the nasty wing tip vortex that is generated by big heavy aircraft. You can't see it but if you are flying slow in preparation to land and you should be unlucky enough to hit it, things can get real exciting very quickly. /forums/images/graemlins/blush.gif

DAP · Mar 16, 2004

Re: Why do helicopters \"chop\"?

Yup. Was trying to keep this a 'family rated' post though. Been there, done that, but had to throw the T-shirt out for obvious reasons. /forums/images/graemlins/grin.gif

FAA enforces 5 mile separation for the liners. Unfortunately, a small plane can still get shook up pretty good. That 5 mile separation is really a measurement in time not so much distance. They figure enough vortex disipation will occur for one liner flying into the vortex of another. Go head, fly directly 5m behind a 737 in a Warrior II. Only thing missin is a guy to collect your ticket, strap you in and set the lap bar!

/forums/images/graemlins/smile.gif

jinman · Mar 16, 2004

Re: Why do helicopters \"chop\"?

( It's primarily the doppler effect with the blades moving both towards you and away from you. )

In radar terms in the late 70s, we call that "zero beat" because on a doppler radar it looked like you had an equal number of targets both inbound and outbound on each side of zero. Normally you had circuitry that would cancel out equal signals like that because they were caused by big slow-moving (relative to jets) helos. /forums/images/graemlins/cool.gif

DocHeb · Mar 16, 2004

Re: Why do helicopters \"chop\"?

Now that you mention it, I can remember (as a 10 year old) the Detroit Riots of 1967, and having my Mom and Dad being really upset. We lived ~14 miles from downtown Detroit, and there were Huey's overhead constantly, flying from Selfridge to downtown Detroit. My dad had the shotgun out on the kitchen table, and after the first day we were sent out with Mom to go camping at Island Lake Recreation Area, far from the city. We didn't go back until a week later, when things calmed down.

lamarbur · Mar 16, 2004

Re: Why do helicopters \"chop\"?

I'm trying to work off memory, but, we know how that is.. THe swashplate at idle, a crew chief can almost run his hand in and out of the turn mass near the Jesus nut.. However, the end tip of the advancing blade almsot nears the speed of sound. The retreating is slower, entering a faster air mass. The blade chord and angle of attack has a lot to do with it also. I did a little over 1200 hours in a Huey, but that was over thirty years ago.. I still takes rides several times a year in Cessna 152/172. If I had the chance, I'd drop everything just to go flying.

gator · Mar 16, 2004

Re: Why do helicopters \"chop\"?

Here Doc, take a ride on a Huey CLICK HERE then push the click here to enjoy a Huey ride button below the picture.

Inspector507 · Mar 16, 2004

Re: Why do helicopters \"chop\"?

gator..........that was great....... /forums/images/graemlins/laugh.gif

DocHeb · Mar 16, 2004

Re: Why do helicopters \"chop\"?

THAT'S WHAT I REMEMBER! Except I need to turn my computer's speakers on full blast, and get rid of my padded chair and sit on a metal bench, and have a few 20 mm bullet holes patched from the outside (but not bothering to patch the inside), and have a patient on the stretcher with me just praying nothin' goes wrong! Of course, there's me just grinnin' right through it all. /forums/images/graemlins/shocked.gif /forums/images/graemlins/grin.gif