Alan Bramson once said when writing about full stalled landings “What happens when a well behave aircraft stalls? The nose drops. What happens when a badly behaved aircraft stalls? The nose and a wing drop.”
Jacko wrote:
A stalled wing doesn’t fly in the sense that most or all of the lift due to the Bernoulli effect is gone, but Newton’s third Law still applies, and that can produce significant lift
A wing doesn’t work like that. Physics doesn’t work like that. Anyway, the wing in a typical “bush approach” is very far from stalled. You will realize that if you retract the flaps and see the real AOA that is needed to stall for the same approach. The air speed indicator is probably also fooling you, you are flying faster than indicated, and with full flaps, you have loads of drag, and this essentially lowers the AOA several degrees to compensate for the added drag (in addition to eventual changes of Cm due to flaps).
if the wing is stalled it doesn’t fly anymore.
Up to a point, but I t’s not necessarily a binary thing. A stalled wing doesn’t fly in the sense that most or all of the lift due to the Bernoulli effect is gone, but Newton’s third Law still applies, and that can produce significant lift. Perhaps not enough for sustained level flight, but enough for a stable descent.
This mode of “flight” works just the same with or without flap. Just cut the gas and slow the machine without raising the nose. We’re not trying to maintain level flight, we’re descending to land. We keep the pitch more or less constant and nail the touchdown point with power and/or slip. Just the opposite of the usual instrument or mountain airfield technique.
Of course, it is possible to come unstuck with this type of approach, to the extent of needing to dip a toe in the aeroplane salvage business, It’s good to practice landing on scattered cloud tops first – they’re softer than grass or tarmac and there’s height to recover any departure from controlled flight.
It’s also probably unnecessary and unwise in windy/gusty conditions.
alioth wrote:
I do need to work on that style of “back country” landing myself (there’s a very good video from some American back country flyers demonstrating the technique)
With the PA18 there is no way to keep the wings level when doing that. No flaps on that aircraft. The nose will be high up in the sky. I don’t know what the best approach actually is, but keeping the wings about level, and sideslipping seems to work fine. It really goes down when sideslipping, and you have very good control of the descent rate as well. But the wing is not stalled. In a sideslip the descent rate is much higher than any other slow descent you can do. Grantly the added drag will make you force the nose down, but still, if the wing is stalled it doesn’t fly anymore.
Jacko wrote:
the underside of the wing is more or less level with the horizon
I do need to work on that style of “back country” landing myself (there’s a very good video from some American back country flyers demonstrating the technique), I think the over the fence (or over the trees) speed in the Auster J1 would be about 35 mph indicated, and a blast of power would be needed at the end to arrest the descent.
The Auster club mag detailed the technique for low observability airfields that they used for the military version of my aircraft (it was used as an artillery spotter). A makeshift landing strip would be made, and so that the enemy couldn’t see where it was by aircraft coming and going, the pilots would drop to treetop height a fair way from the strip, flying at 35 mph. The touchdown point would be marked by a (gutsy – or actually probably ordered to stand there) member of the ground crew who would stand to one side of the indicated touchdown point with his arms out to make a human “T”.
Departures were similar, break ground, then fly at treetop height until away from the field then climb out. Artillery spotting itself would again do something similar, slow flight just below the treetops in a circuit, then power up and pop out to take a look at the target, guide the artillery, drop back down, then pop up again later to see where the shells hit and radio in a correction if needed (all the while trying to do it in a way that you didn’t get hit by your own artillery!)
I just did the line drawing measurement for a Luscombe and get roughly 15 degrees AoA in ground attitude, which I think matches my experience that you can land tailwheel first but not by much on that type. It also depends on the tailwheel and spring used, and I know some owners who dislike large tailwheels (e.g. Scott 3200) on a Luscombe for that reason.
Mark_1 wrote:
I’ve never flown any tailwheel aircraft that are stalled in the 3 point attitude.
I doubt if anyone has ever flown one that can’t be. A wing can be stalled at any attitude, and at any speed.
So, for example, this wing is partially stalled as soon as it comes over the trees (from time 0:17 to 0:22), but the tail of the aircraft is well up. The rate of descent is about 600 fpm but we are not diving; the underside of the wing is more or less level with the horizon. After time 0:22 the driver has two choices, to lower the nose so as to get the wing working again, or to rotate to 3-point, give it some gas and plonk it on to the paddock. (Clearly, he hasn’t got the b@lls to drop the nose, but the latter course of action seems to work well enough. He also seems to lack the courage to stall the wing deeply until clear of the trees, costing a few precious yards):
As @what_next indicated, keeping the tail up for the landing should work just as well, or possibly better if maximum braking is required, but it’s a somewhat counter-intuitive technique which this geezer hasn’t mastered.
P.S. In post 04 above, delete “angle of incidence” and substitute “angle of attack”. Sorry.
Hmm, this is the kind of thing you need to do experiments about. I think I agree with alioth for the time being. The flare makes you run out of speed (energy) to fly, not so much “out of angle” to make you stall.
On a Luscombe its possible to touch the the tailwheel before the mains, but not by much. The stick is “locked back” just before the plane touches the ground, with plenty of roll and yaw authority remaining. RVs seem to be ‘flown on’, at least the RV-4 and RV-8 in which I have some limited experience. IME its mostly classic types with low wing loading that can be ‘full stall’ landed… although that description is not strictly true either if the wing has some washout, it’s more a partially stalled high drag situation.
I’ve never flown any tailwheel aircraft that are stalled in the 3 point attitude.
My first CFI used to have a skill exercise in the Auster to slow to the 3-point attitude with a trickle of power, carefully lower the aircraft and try to fly down the runway with just the tailwheel on the ground. It certainly taught some finesse in your landing technique.
At the other end of the scale Delmar Benjamin attempted to 3 point the GB replica during early test flying and got aileron stall and control reversal ending up with a scraped wing tip (left unrepaired as a reminder). After that he only did wheelers (at about 120 MPH).
