I didn’t think the soft field bit was bad – but he didn’t lower the nose and gain speed after lift off – and the trees might have made it impossible to successfully take off.
Even on a soft field, it seems to be struggling to get airborne quickly, and even when it did, it should have performed better. I couldn’t see inside, but was it fully loaded?
First of all, it looks like he’s not using all the available field, there seems to be space behind him at the beginning of the video, although hard to tell here. Secondly, as Maoraigh says, he doesn’t lower the nose to gain speed while still in ground effect. What he tried here – powering up and out of a field like this – isn’t gonna work with a 172….. Hard to say if this would have been possible at all, given the trees at the end, although the field itself looks quite ok.
I speculate (because I see a jump step on the right gear leg) that it was a jump plane. Old 182’s are commonly used for this thankless role. It is rare that they take off empty (‘cause no one is paying!). Sometimes the jumpers are more heavy than they declare, or worse, no one asks them! Sometimes jump pilots are low time timebuilders, who have yet to refine these skills. The Pilot Operating Handbook for that aircraft specifies 20 flap for this kind of takeoff, that plane had only 10 extended. That’s a pretty rough field, and hardly looks anything like a “runway”, that’ll sure detract from takeoff performance! And, as pointed out, the pilot did not lower the nose once airborne. Other than perhaps trees at the end, that was otherwise a doable takeoff, if flown properly.
A soft field takeoff will not be a short field takeoff, you gotta decide which you are doing before you apply the power, I’m not sure this pilot decided….
I speculate…
No need to speculate, the original description of the video on YouTube reads like this: “As the pilot of this Cessna attempts to takeoff in a cornfield he overcorrects in gusty winds causing the wing tip to contact the ground, spiraling the plane into the field. Despite the ensuing fire that consumed the cabin, the pilot was not injured. The pilot had initially landed in the field due to strong winds, heavy rain and low fuel. (1997)”.
But I can not really see the “…overcorrects in gusty winds causing the wing tip to contact the ground…” bit in the video. To me it looks rather as if he was fixated by the tree tops from the moment he released the brakes and did nothing but aim slightly above them. Thereby the aircraft lifted off early and never accelerated out of the stalled condition.
There’s also just recently been extra emphasis on a problem that’s not well understood: the stall speed is different in ground effect compared to out of ground effect. This is one of the reasons that killed the test pilot crew during the certification of the new Gulsftream G650 when it crashed at Roswell, NM. Your AOA can be higher in IGE than OGE. The G650, as it climbed out from a max AOA scenario on one engine, stalled and dropped a wing that started dragging.
This is one of the reasons that killed the test pilot crew during the certification of the new Gulsftream G650 when it crashed at Roswell, NM.
Yes, but not because the ground effect (which was discovered by Otto Lilienthal in 1880) is not well understood, but because Gulfstream didn’t do it’s calculations right. See here: http://www.ntsb.gov/news/events/2012/gulfstream/ There is no final report yet, at least not one that I could find on the internet, but the preliminary one says: “Further, Gulfstream did not validate the speeds using a simulation or physics-based dynamic analysis before or during field performance testing.” and “If Gulfstream had performed an in-depth aerodynamic analysis of the cause of two previous G650 uncommanded roll events, similar to the analyses performed for roll events during previous company airplane programs, the company could have recognized that the actual in-ground-effect stall angle of attack for the accident flight test was significantly lower than the company predicted.”
For me, there is a big difference between “not well understood” and “didn’t bother to calculate/investigate properly”!
I was never taught anything about it, nor is it part of any PPL curriculum I’ve heard of, pr special emphasis item.
Adam I believe is correct. Effective angle of attack, and basic concepts of 3D flow are taught at ATPL, but not really covered as a principle of flight item at PPL.
There is also no specific requirement to teach soft field take off technique in Europe, at PPL or CPL, although I believe you are formally taught it in North America. It is spelled out in the Cessna POH, see below for example. I do add it to the course, as in the UK we get our fair proportion of soft, damp ground conditions.
Soft or rough field takeoffs are performed with 10° flaps by lifting the airplane off the ground as soon as practical in a slightly tail low attitude. If no obstacles are ahead, the airplane should be leveled off immediately to accelerate to a higher climb speed. When departing a soft field with an aft C.G. loading, the elevator trim control should be adjusted towards the nose down direction to give comfortable control wheel forces during the initial climb.
Although the no obstacles ahead phrase may lead to confusion. You should still be able to accelerate to Vx and resume climb, not have to accelerate to Vy.
In any event the early 182 series are a great aircraft with variable incidence tailplane trim and a bush pilot power to weight ratio.
One unexpected consequence of ground effect is the reduction of the critical (stall) AOA. I’d never heard about that until recently when I read this excellent book: http://www.av8n.com/how/
