I’ve seen loops by helis but never extended inverted flight. A fixture at the Paris Air Show during the '90s was a demonstration by an Aerospatiale (now Eurocopter) Panther that featured multiple loops. I witnessed this myself at two different shows. The loops were… strange, as they were far tighter than anything I’d seen done by a fixed-wing aircraft; more like backflips than loops, really. My understanding is that the heli must have a rigid, rather than rocking hub for such maneuvers to be practical.
If anyone is interested, here’s some further discussion from the Skunk Works Digest on aerobatic maneuvers, among other things, by helis.
Plenty farther than 45 degrees. As long as the vertical component of lift equals or exceeds the load, then the helicopter will not descend. I’ve had helicopters in banks as steep as 75 degrees and maintained level.
Horizontal acceleration is going to be dependent on how much the horizontal component of lift exceeds centrifugal force. But you are right, it won’t be capable of hovering in one spot if the main rotor disc is banked. (eliminating the wind factor).
I only viewed the video once, and I was too busy being amazed at the talent that guy has, to spend much time analyzing the flight. There were times that the camera perspective made it difficult to see exactly what position the helo was in.
I suspect they didn’t break any laws of physics during the flight though.
If you notice, the action is pretty much contained within a given range, and although there are quick movements, they don’t go forever. The camera operator is good, and could well be familiar with the helicopter operator’s moves, but not to take anything away from the camera operator, I don’t think they are comparable.
I’m with **Starguard ** wondering “how many choppers did he go thru (crash) before he learned to fly like that?” I’ve got a little indoor RC helicopter I just got and just getting it up in the air has cost me a number of rotors.
Do they sell this in the States? It’s a little 100 gram RC helicoptor. The site is in japanese, but if you “Windows MediaPlayer” you can see a demo.
I would be very interested in seeing anything like this. I am in the last month of my doctorate in aerospace eng. working on helicopters, have friends working at NASA Langley, NASA Ames, Boeing, etc, etc, and have a friend who currently flys Apaches in Kosovo, but I have never heard of a manned helicopter maintaining inverted flight. Sure, loops are fine, but the rotor is still producing positive lift (as noted by the “backflip” comment in earlier posts).
If you try inverted flight your base coning angle will be close to chopping off your bloody tail boom.
OK, I have googled this quite a bit, and found nothing, though with all the R/C stuff I had to sort through I might have missed something. Any links about a real helicopter being inverted tend to be like the following:
“…the helicopter inverted and crashed, killing the pilot.”
“…helicopter’s tail and the main-rotor system sustained catastrophic damage, rendering the helicopter uncontrollable. The helicopter pitched inverted and plunged…”
“The helicopter inverted and crashed into the river…”
In fact, I couldn’t find anything about a real helicopter flying inverrted without “crash” appearing later in the sentence.
I watch Discovery Wings a lot, and I’ve never seen amy sustained inverted flight on it. Looping and rolling yes, but nott horizontal flight or hovering. I don’t believe it’s possible, but IANA engineer.
If you can get access to the DIY channel, there’s a show called “Radio Controlled Hobbies”. I’ve seen these helicopters on there and what is shown in the video IS possible.
I must say, it looked entirely real to me (and awesome- the chopper looked EXACTLY like a dragonfly in terms of its movement at some points) except the part where is simply hovers upside down an inch above the ground. Watch the rotor blades very carefully- they are revolving only about once a second. At that speed, they can’t be generating much more force than a ceiling fan.
RNATB that’s an illusion created by the “shutter speed” of the camera and the blade rotation speed. Digital video cameras have this problem more than old analog ones. I’ve seen video of airplanes in flight where the prop appeared to be making slow, lazy rotations that could never maintain flight. Someone more familiar with video cameras could explain it better, but it’s really just an illusion.
You can see the same apparent slow rotation effect on car wheels, at night under some typrd of artificial lighting conditions, without a camera involved. In that case, the affect is produced by the interaction of “blink rate” of the lighting, flashing in and out of phase with the rotation rate of the wheel. At certain speeds, the wheel (most often the hubcap) appears to be at a dead stop as the car races down the road. It’s commonly called the strobe effect.
The effect can also be seen in racing games, such as F-Zero on the Nintendo 64. The railings at the sides of the road is often a small pattern that repeats. When you reach high speeds the railing will repeat one or more times between each frame.
For the record, the Raptor 60 has a rotor speed that ranges from 1750 to 1850 rpm, or 30 rotations per second, and video is capture at 30 frames per second. This accounts for the strobe effect which gives the appearance of one rotation per second.
One answer may be post-production. If your video camera has a resolution of, say, 1024 x 768, and you are producing a web video of 320 x 200, then when you are editing the video you can Pan and Scan a 320 x 200 window to keep the helicopter in view at all times. If you saw the raw video, it would look like it was maybe 4x bigger, and the helicopter would be a small dot in the frame.
You can use the same technique to get rid of jitter and unsteady camera work. In fact, that’s how electronic image stabilization in video cameras works - the actual number of pixels of the CCD is bigger than the final image, and the camera moves the image window around to compensate for camera shake.
The higher the resolution of the original footage, the better job you can do in editing.
I’m almost certain that the video must have been cropped to keep the copter central where possible - in cases where the camera is panning rapidly, there is no overshoot at all when the machine suddenly banks and there’s none of that oscillation that is almost inevitable when tracking a fast moving object.
