The few techniques around for quick takeoff & landing seems to be designed for soft*+*short fields with empty loaded tail-wheels/skids aircraft, I am really not sure how much of those would apply to a fully loaded PA28?
For sure when landing a PA28 and pulling the stick against its tail-skid that will give a quick stop, in the other hand, one does not need to lift its tail in the early acceleration phase before takeoff
He reasoned that on a soft surface the first 10kts are the hardest to get, so advocated performing one’s lining-up turn at a reasonable speed and applying full power just before one is fully lined up.
Yes, the problem there is to avoid getting stuck indefinitely (irrespective of power or length of runway ahead)
On acceleration and runway length, I doubt you will get that much benefit from a 4meter turn arc compared to the 400m of runway ahead? how much that is different from taking off on 404m runway?
I think the technique and the order of how you do stuff depends on your end to end problem: 1/ getting at runway end at 50ft with max speed? 2/ max height on top of end of runway at Vx? 3/ minimize your ground run?
All of these will require full power on breaks and neutral AoA (stick forward for zero aerodynamic drag or tail-wheel/skid friction), zero flaps initially (to maximize power to speed transmission) then “change to 2nd gear later”: takeoff flaps while you pull the stick and accelerate in ground effect with neutral AoA and “change to 3rd gear”: climb at Vx, Vy at some given point where speed is higher than Vs0/Vs1…then it gets complicated when you add cross-wind and stability
Ps: I am not suggesting to any one to fiddle with takeoff flaps or any other levers while on ground run or effect
Flying the Robin from grass, when I wanted a little ‘extra’ for whatever reason. (Very wet, soft, heavier, shorter) keeping rolling and applying full power as turning to runway heading really worked for me.
Full elevator to lift the nose. As the speed increased I’d loosee the elevator to present less drag, then reapply when ready, to get into ground effect.
Once in ground effect she’d accelerate nicely, and away we went.
Not saying that’ll be good for a TB10. Just confirming that it worked IMO for our Robin.
I’ve been told the soft field technique in the C152 manual is not good for the Robin nosewheel aircraft.
Downpressure by the elevator reducing nose load, but increasing mainwheel load. The balance is different.
I’ve no soft field experience with the C150/152/172, and none at all with the Robins.
Some points made here bear repeating for emphasis:
Generally, a short field takeoff most emphasizes accelerating the aircraft, rather than trying to drag it off the ground early. Get it to takeoff speed with minimum drag (deflected controls), then lift off, and climb as needed for obstacle clearance. A soft field takeoff emphasizes getting the weight transferred from the wheels to the wings as early as possible. There will be increased drag, and thus the takeoff distance will be longer than a properly flown short field takeoff from a firm surface.
If a runway is soggy, it’s got to be a soft field takeoff technique. However short your takeoff will be, will be what it is, you can’t have it all. A short field technique on a soft runway will bring you to grief.
Stabilator type airplanes are less good at soft field takeoffs, though should be equal in a properly flown short field takeoff, as long as you fly to the book speeds. My experience in PA-28’s and C 177’s has shown me that if you use full up stabilator to drag the aircraft into the air, you can stick yourself in ground effect. The fully deflected stabilator will begin to stall, and so the drag being produced can become so much that the power cannot overcome it, and though airborne, you may not accelerate enough to get out of ground effect. Twice I have been right seat when a pilot has done this. It’s usually hot and heavy that tips the balance and creates the trouble. In one case, it was only my retracting the gear in the Arrow which reduced drag, and got us out of ground effect, we looked doomed for a short time. The earliest C 177’s had an AD to add the inverted slot that all the later ones have, to reduce the risk of stabilator stall.
As said, both of these techniques must be well practiced with lots of space, before being used out of necessity. Other than when carrying passengers, every takeoff I do will either be a practice short or soft field technique (unless it’s for real) – just to keep fresh on technique.
The other important thing to remember, is once airborne, you must clear the obstacles. Not clear them with a silly excess of altitude, just clear them. If you must climb at a speed slower than Vy, you are in jeopardy, should you have an engine failure. Most singles will not safely enter a glide close to the ground from slower than Vy. If you have a sudden EFATO at a hundred feet or so, slower than Vy, by the time you recognize it, and lower the nose, you’ve slowed and descended. You must have a reserve of speed with which to flare, and if you were only at Vx, you may not have that speed reserve. This should be practiced on the type you fly, at altitude, trying to arrest your descent momentarily from a glide, at a “hard deck” 100 to 200 feet below you, with a sudden power off, at progressively slower speeds. You will find a speed at which though you can glide, you cannot arrest your descent, and you’ll settle through your hard deck with the stall warning sounding – that would have been an unsuccessful forced landing! I’m impressed with the very short takeoffs demonstrated at the STOL competitions. I am depressed to see a pilot then drag his aircraft up a few hundred feet, hanging on the prop, as though there were a reason – there is not, unless there is an actual obstacle, and the risk benefit is such that you should risk a crash after EFATO to make the takeoff. When I train forced approaches, they are to a landing each time. Things are different when you’re not applying power at 50 feet to overshoot your practice!
Thanks for the great post, Pilot_DAR.
It’s a funny thing… I was never taught short field or soft field takeoff in the UK PPL. It was first seen in the FAA PPL, 4 years later, where I flew ~5hrs to cover the extra stuff. The FAA accepts all non-US training towards any US license or rating. I did that in the UK, back in the days when it was fairly easily arranged.
It was an eye-opener, especially the soft field takeoff which is really different to anything previously experienced. That was in a PA28-181 which has a fair bit of power. The TB20 has similarly a lot of surplus power; way more than a TB9/10.
Nowadays I rarely do it because grass ops, and 10x more “muddy” grass ops, cover the whole plane with crap which needs to be cleaned off and creates more work at the next Annual. There are so many nice places one can go to in Europe where one is not dragging he plane through mud…
The other important thing to remember, is once airborne, you must clear the obstacles. Not clear them with a silly excess of altitude, just clear them. If you must climb at a speed slower than Vy, you are in jeopardy, should you have an engine failure. Most singles will not safely enter a glide close to the ground from slower than Vy. If you have a sudden EFATO at a hundred feet or so, slower than Vy, by the time you recognize it, and lower the nose, you’ve slowed and descended. You must have a reserve of speed with which to flare, and if you were only at Vx, you may not have that speed reserve.
Thanks for the detailed post, any good case to climb at Vx apart from PPL book suggestion regarding max angle climbing in “free calm air” ?
Near the ground things are much different: ground effect, wind gusts, turbulence to make Vx meaningless or even dangerous, also obstacles and “free calm air” don’t mix that much for trees/hangars/hills, the only obstacles that produce calm air are pylons, masts and the fictitious noise abatement box
Here is something that puzzles me a lot, which one allow you to clear a real life obstacle? 1/ leaving ground effect and climbing at Vx versus 2/ accelerating to Vy on ground effect then climb while pulling back to Vx? Personally, I won’t try 1/ if 2/ does not work so no way for me to test it…
Ps: the same story for landings not at best glide Vbg or min sink Vms, but probably not far from Va = 1.3*VS0+/-adjustment(wind/gust) when close to the ground…
For those times where clearing an actual obstacle was a concern, the practiced technique I liked the most was to allow the plane to accelerate to at least Vy, and lift off the runway. I would then aim for about midway up the obstacle (nearly always trees), as though I were trying to take them out with the plane. When my Spidy senses tingled too much, I would ease back and allow a combination of power and inertia carry me over the obstacle. I never brushed leaves with the wheels, though I would not have been too concerned if I’d been close. My objective was to clear the obstacle, and retain a nice reserve of speed. Being 150 feet higher than the obstacle and too slow was very much where I did not want to be! Only once did I fly a prolonged Vx climb, and that was departing Innsbruck. ATC gave me a left turn, which I accepted sooner than I should (trying to be a nice guest in Austria and all). The turn took me toward rising ground too close for my comfort. I flew a very careful Vx to departing downwind, but allowed my downwind to crowd the airport more than usual, so if it did quit, I would be gliding toward the airport. It was not good, in that Vx as 20 knots slower than the most suitable glide speed, but by then I was climbing through 700 feet higher than the airport so I had some room to play. I was wrong to accept the left turn so early though, I was trying to make room for a Dash 8 departing behind me, and I should have just made him wait a minute more…
Vx climbs get considered (and mis managed more) on float and ski flying, where you are nearly always departing from not a runway, and with no real distance available information for your departure path. This can be coupled with the probable need to back taxi a float plane at a very slow speed, and it seeming to take forever. Some pilots can’t resist, and turn around to begin the takeoff too early. Runway [lake] behind you on takeoff is useless. Dragging a plane up a slope or over trees can be terrifying! The one trick on a suitably shaped lake which has a large enough radius is that you can takeoff in a circle. I’ve done it a few times, and getting airborne into a turning climb parallel with a turning shoreline is more reassuring than climbing toward it too slowly!
Short field take-off in aTB10? That is really a contradiction in terms!
The TB10 wing behaves very differently to either a Cherokee or a Warrior wing. If you try to haul it off at minimum speed, it will simply sit there at that speed, but it is never going to climb. In my experience, the TB10 wing needs to be accelerated to 80 Kts before it will climb.
Suggest you try the different methods on a nice lng runway.
If it helps, I have a diagram giving the distances between the thresholds and runway intersections at Waltham.
GA_Pete’s technique for getting a Robin off a sticky wet grass runway plays to the aerodynamic strengths of what is a very sophisticated wing section.
Trying this with the more aerodynamically pedestrian slab wings such as the early PA28’s of TB10 is likely to be unsuccessful.
Thanks Tom. The diagram would be really helpful as I do need to do some experimentation.
Of course I understand it’s not a short field machine, but I still need to work out a way of getting the best out of it if I’m to take it to places like Glenforsa. The POH would normally be the first port of call, but it is silent on the matter.
She is a lot better since we had the new engine just before Xmas and will now climb away happily at significantly less than 80kts. The book gives best angle as 65kts and best rate as 78kts. I eased her off at 65kts last time I flew (2 up and almost full tanks) and while there was a momentary chirp from the stall warner (which sounds a good margin before the actual stall) she did climb away out of ground effect and accelerate.
It is difficult to experiment at White Waltham since the bumps mean one is often thrown into the air involuntarily before reaching the speed one wants to rotate at.