With apologies to Phil/Voltair, I would like to repost what he withdrew a few hours ago, because I value his response to this discussion of a video demonstrating the unsuccessful use of a PPG obtained via Amazon. If I’m not mistaken, this forum is not merely for PPG builders or buyers, but is also where actual and potential flyers can discuss and learn from the more experienced among us. I’ve omitted a few bits, but here’s the gist of the discussion so far:
On Mon, Apr 5, 2021, Phil via OpenPPG Community firstname.lastname@example.org wrote:
I have to apologize for the long response and somewhat drifting slightly off topic, but I hope you will get something positive out of it.
Food for thoughts:
The pilot in the video is actually is a very experienced Paraglider pilot https://www.youtube.com/watch?v=BNAXTKQq_V0 but had never tried to takeoff with a coffee grinder attached to his butt.
It looks like there was also a gust factor or sustained wind speeds. You can hear the wind at the beginning of the footage as he is inflating his glider and keeping it overhead. There was a velocity high enough to keep the glider inflated before he turned around, meaning that the wind speed was at least 6 or 7mph.
He faced and ran upwind after turning around (all good).
Acceleration and torque take place (normal).
The torque works with the counter rotation but also on the yaw axis. The motor forces the frame/harness/pilot to spin right but not the wing.
The pilot fights the yaw effect by braking left 0:08
The pilot increases the brake pull to the left to face the wind 0:09
The pilot brings his hands up and levels them (good)
A cross wind at higher elevation hits the wing and pushes it right spinning slightly clockwise
The pilot decelerates to zero RPM as the wing crabs right pretty fast in cross wind speeds.
The pilot brakes 0:14 while drifting right.
The pilot makes a cross wind landing (that could be an ankle breaker by itself, especially if not wearing proper footwear.
It is already difficult enough to make a clean landing approach just about anywhere free-flying; adding 60/70lbs onto the pilot’s back increases the odd of screwing up. Imagine your spark plug cap taking a hike in mid-air,… then what?
Here’s a relatively new pilot who didn’t quite understand the mechanical aspects of the whole routine (lee side, rotor, lost of lift, drift, did not correct the situation on time, when he could easily have, flying cross and downwind) https://www.youtube.com/watch?v=pAiRTS9feZ8
But wasn’t it a mistake, Phil, to cut power before stabilizing flight in whichever direction, even crosswind? It seems to me that overpowering the crosswind effect and gaining altitude would be the only hope of then turning upwind. Nonetheless, what would you suggest doing about the p-factor yaw?
On Thu, Apr 8, 2021, 03:14 Phil via OpenPPG Community email@example.com wrote:
In the video:
The pilot realized he would not have enough space to land had he continued climbing because of the obstacles around him (small park) and reason why he aborted the flight.
You do not power up if a gust hits your glider on the leading edge. You reduce the angle of attack by reducing the RPM gently and handle your wing the way a paraglider pilot would. An even higher angle of attack would bring the wing closer to a lockout. It is possible to send a wing under full power with a motor delivering a lot of thrust into a lockout. I have seen it with pilots blasting their way to the Moon regardless of wind conditions. Pin the throttle and “Good luck Charly!”- Go! Space-X go! This is how towing accidents often happen, especially when the glider hits a gradient and when the operator doesn’t know what he is looking at, not reacting on time with precise corrective measures to mitigate the problem immediately before it turns into a nightmare scenario (it happens mostly with stationary pay-in rigs) which I use often to tow my students.
All accidents are different. I recommend my students not to watch crash videos on YouTube because they will not learn a thing other than the pilot screwed up. One’s reaction under stress will never match yours in a similar situation and reason why we cannot be critical after the fact. Yes, we can point out what happen frame by frame but it will not change the end result. Who know what someone else would do in a similar scenario?
Schools exist to teach basics and drill safety rules into the newbies craniums. Telling them why things can fly or not, how the mechanics work, observe the birds, the environment, think ahead all the time, etc… but the sum of those guidelines cannot cover all the scenarios encountered when flying - impossible! Once certified, the rest is up to them to define their safety envelope and stick to it to enjoy safe flying. It is all about balancing risk and reward. They is no magic pill to solve every situation. Let’s put it this way, we can kind of control 99% of our flying if we stick to the rules, and there is the 1% left we cannot like getting attacked by a bird kind of stuff. This pilot collided with an eagle in the French Alps https://www.youtube.com/watch?v=6KNbeP1xKZw
People always ask me what do you do if you get caught into a cloud suck? They expect me to say, you pull this and that, do this or that, and they are always surprised when I give them the short answer: “You should not have been there at the first place!”
Basically, the PPG pilot on the video, should have stayed put. Never mind trying to fix the problem he created for himself. He was out of his comfort zone for not understanding powered flights. It was his first time trying to fly with an egg beater, and no matter how good he is paragliding, paramotoring is a different ball of wax even if the wing he used when thermaling the mountains was the same for paramotoring.
He screwed up when thinking he could fly with a motor without proper training because of his PG skills. And again, professional training can only go so far. The rests is up to the pilot to understand what he will be facing as soon as his feet will leave the ground.
Thanks for your educational reply, Phil, and I’m sorry you withdrew your posts. They seemed to me sufficiently on-topic, though not directly addressing any particulars about the subject product featured on Amazon.
If I may, I’d like to ask you to clarify two terms you used. One was “lockout”, which seemed to mean a full-power aerodynamic stall of the wing. The other was “cloud suck”, which I didn’t really understand. Is there a low-pressure phenomenon close to some kinds of clouds that would draw a light-weight low-powered craft into the body of the cloud, where I imagine turbulence could seriously disrupt the shape of a paragliding wing with catastrophic consequences. My own flying experience with clouds is limited to traditional small aircraft that would not be susceptible to such a phenomenon, therefore I ask if you know of some subtlety that wasn’t addressed in my own aero education.
The other aspect of my post, that your withdrawn reply didn’t address, was my question about handling the yaw induced by an “egg-beater” or “coffee-grinder”. It seemed to me, in the video, that this “Amazon” unit produced more yaw than I’ve seen in other EPPG videos. This surprised me because the unit seemed spec’d at a lower power than, say, the SP140. But perhaps there were other factors that I didn’t perceive.
I’d appreciate very much your response.