Calvin19

Wow... I could not agree more. I have taught a few (yes, less than 5) students through to A license by Deathcamping and IAD. I have seen AFF vid gone wrong, and flown in on a few AFFs. AFF, to me, seems like the worst idea in the world. Hey instructors! wanna have fun? lets take some idiot that watched MTV a bit too much, put a parachute on them, take a few hours explaining what they are supposed to do and then LITERALLY put them in the most stressful moment of their life and bet on if they can count to three or not.

It looks like it was taken from a fast moving airplane at a high(ish) altitude. And, I would bet a good amount of money that it was a small helium balloon. Relative motion is an awesome thing.

"beer is good"

If you could, would you summarize his latest post? It's like I need a Rosseta Stone to understand it.

Sooo... you're agnostic?

Are you seriously asking that question?

@ 1:23 ~ point of impact you can see something kick up spinning, is that a rock ...or Jebs helmet? I thought it was a black balloon. -SPACE-

Not the old dactyl, the new(ish) PG rescue. I really did not think the landing was that bad. https://www.facebook.com/photo.php?v=582384696271&set=vb.203002032&type=2&theater -SPACE-

I did ~5 wingsuit jumps on a borrowed GTI for my 50-55th skydives, then ordered a V1. I did ~150 skydives on it since 2005, and ~200 BASE jumps on it since 2007. I gave it to a flightless friend as he was on his was to Norway in 2011. I am suitless. If anyone has a V4 that would fit a 5' 8" 155 pound male, I'm buyin.

It is a Rogallo wing. I have a Rogallo type paraglider rescue rogallo. They are considered (in both paragliding as well as skydiving) as less than reliable, therefor acro pilots also carry a round rescue parachute. (yes, two reserves to use in case of an acro PG emergency, the steerable rogallo if you have the altitude to deal with it, the round if you are low and in the shit). Pic is of me jumping the older rogallo rescue from a plane. The rescue is called the Beamer. This one built in 2008. I think it is 38m. The new one is white and weighs almost half as much as the yellow/red beamer. https://www.facebook.com/photo.php?fbid=582346687441&set=a.535697637511.2049462.203002032&type=3&theater

What size? I've flown a ton of .26-1.0 nitro planes. Trainers to Acro to Helis. I tore the ailerons off a .15-.26 sized trainer by putting a .65 on it. It buried a good 2 feet into the ground. good times. I wish gopros were around then. (~1999)

Interesting article. Good points. I hope no one is trying to quote something out of context to defame electric transportation. I'm sure the rescuers would rather themselves and the victims be at risk of burning alive in a gas fire. Not that batteries are totally safe, of course. On a similar note, years ago I was sponsored buy a Rescue equipment company. The owner was using my friends and my rope jumping to advertise his rope rescue equipment. He gave me the low down and a demo on a cool "airbag contaminate" net. The idea is to contain an airbag "misfire" if there was a wreck and the airbag had not fired, but part of the deployment sensors were triggered. Airbags are pretty intense, if anyone has been the recipient of a pillow explosion you know that it could really kick the shit out of an EMT trying to access a victim.

Though I do agree with your comment, in my particular case it is not friends but rather family. Not direct close family but just far enough down the tree that if I were to stand my ground and assert my authority with my wife, it would be a very lonely patch of land that I would be claiming :) Responses to Calvin19's comments may only be made by his friends.

It's pretty easy to just unfriend people that get married.

Very cool story. Makes me want to become an instructor.

I did a few intentionals on a Javelin with soft loops for the cutaway and reserve handles. I liked it a lot. Easy to grab and easy to hang on to after the cutaway. -SPACE-

Inglip will kill you in your sleep.

the bar he set is at his ankles.

Not sure here, but I would like to share how I think it is. The vector of the induced drag changes with speed, it moves forward. This is also the result of ground effect. When viewed as an equation as speed increases for a given load, the average angle of attack of a wing approaches zero. This means that the ability of ground effect to have a measurable influence on an aircraft also approaches zero[as speed is increased]. Thus, ground effect's perceivable influence decreases as speed is increased. Edit to add: But, you might be able to argue that from the standpoint of an observer, a sailplane can travel significantly farther and for a longer period of time while in ground effect at speed than it can at landing speed because of the same factors I just sited. (the aircraft is in very low AOA and low camber configuration, so the difference between gravity and induced drag is very small allowing the vehicle to travel with minimal drag, and any small gain would appear to be amplified by these factors.) -SPACE-

[confused face] I know, I have done that in a 102. exactly what I was doing in the PA30, minus the damage and crash. It gave me an extra 5kts at a given power. Ekranoplan. Ground effect vehicle. there has been several civilian "swampboat" versions as well. The ekranoplan also "flew" very low, and only very low. -SPACE-

Is it possible that nobody ever thought about it in detail because nobody figured people would be flying at a height of less than their wingspan off the ground? I have thought about it a lot since about 2003 when I started. I imagined there would be ground effect. BUT i -think- the lifting methods and ultra turbulent flows of wingsuits would make the standard "one wingspan" rule less than reliable. -SPACE-

Calvin, I agree in general, except that my suggestion is that ground effect may have played a role in the "Grinding the Crack" video, not this incident. http://www.youtube.com/watch?v=TWfph3iNC-k Watch at 1:36 and see the additional lift at 1:40, and consider the altitude above the smooth slope, how much was ground effect? I have no idea. I have no idea either. Without testing and and ways to test there will never be hard data. In that video, at the times you specified, as well as other sustained consistently very low flights, there very well may be a significant amount of ground effect. It seems you are very informed on aerodynamics, probably much more so than myself. Please take what I write here and what I have written in this thread before as opinion based on experience and a limited education in aero. Ground effect is a complicated thing. {in response to someone else] To say that "an X-24 experienced ground effect" is in no way untrue, but No one ever flew an X-24 at low altitude in a high speed configuration. Ground effect is not "on or off", it has immense variables and not only between different aircraft. An F-4 Phantom no doubt experienced ground effect on landing, and probably around an AGL of one wingspan. But what if a pilot took it to the deck at 300kts? at one wingspan, would there be significant ground effect? how about 500 kts? Sure, the effect would be there but most likely not noticeable. At about 130kts I have, and for long periods of time, taken a PA-30 (with the gear up) to about an altitude of 12" prop to water. Where the gear down, it would be dragging in the water from time to time. This is about

Yeah. They called me at home. Bravo. [golfclap] This is Bonfire, we are both allowed to make our sarcastic and completely useless contributions. -SPACE-

Yeah. They called me at home.

Great. You pointed out that I used an incorrect definition of one term within the context of the point I was trying to make. How about contributing something to the thread and either provide a correction to my definition, or better yet, realize that the point of my post wasn't to define 'lift', it was to comment on the validity of claiming that wingsuits benefit from ground effect, and that it played a critical role in a previous wingsuit flight, and contribute to that discussion. For an over qualifed college professor, you sure post like a high-school drop-out sometimes. Because a suit and its pilot can travel at a trajectory not equal to and not decaying toward the gravity vector, there must be a force to maintain that trajectory. This is accomplished almost entirely by the net effect of fluid(air) being turned or deflected from it's original state, thus creating a dynamic force that In physics we call lift. A wingsuit is most definitely flying. As for ground effect, I too doubt that it played a significant role in this incident. I also doubt that it has much observable effect on any "proximity" flight done by a wingsuit. For one, the general rule of aviation ground effect would show that it is all but inapplicable to most wingsuit flight currently being shared via publicly viewable video. Of course, the GA common belief of aerodynamics in not always similar to the true physics behind the events.