although I believe you are formally taught it in North America.
Correct, both short and soft field techniques are part of the FAA PPL.
Curious if there is also a “short and soft field” technique?
Mind you, this is not an attempt at flippancy. I cannot help being sceptical about all these different techniques, and tried to word that with a smile.
But as I was taught, there is only one technique for any condition:
-) get airborne as soon as possible (which includes full power, full back elevator, and flaps as appropriate for the type)
-) once airborne, gain sufficient speed as fast as possible, this normally requires some less back elevator
-) one speed is sufficient, climb as fast as possible, this normally includes reducing flaps
What need to make matters more complicated?
But I do realise that I speak only from the experience of a simple low performance aircraft – perhaps some of the finer nuances do not apply to my kind of flying.
In many aircraft “full back elevator” would result in the aircraft never getting airborne.
The soft field technique will require some more take off distance while you accelerate in ground effect, and may require more ground run (more induced drag and flaps). Hence STOL competition technique can be flaps up, then you pop the flaps (assumes you have a Johnson bar) so you accelerate clean.
All type dependant.
@Neil: OK, I should have worded that more carefully. Actually, on my own microlight the “back elevator” must be reduced as soon as the nose wheel leaves the ground, or my crash would be like the one pictured. One instructor insisted I should roll (on the main gear only) at the same upward angle as the plane has during strongest initial climb. But we are now talking speeds of 60-80 km/h or so.
@Robert: yes, agreed, the practical details depend very much on the type of plane. Still, whatever field one takes off from, the prime goal must be “get airborne as soon as possible”, the second “gain sufficient speed” ? I still fail to see why that should be different on a soft field vs. a short field.
Jan, the purpose of a soft field takeoff is to lighten the load on the wheels during the ground roll and “get airborne as soon possible”: If you then stagger along for an extended runway length gaining speed in ground effect before climbing, that’s OK because you got the wheels out of the mud. So its by necessity a different technique than you would use trying to clear an obstacle departing from a nicely surfaced but short runway: in that case you let the plane accelerate more with weight still on the wheels.
It seems to me the two techniques and their inclusion in flight training must’ve been formalized about the time tricycle gear planes came into flight training. In a tailwheel aircraft the principles are the same but the techniques are a bit different, and more type specific.
Still, whatever field one takes off from, the prime goal must be “get airborne as soon as possible”, the second “gain sufficient speed” ?
Actually, no. There are (at least) two conflicting goals
• Get airborne before you run out of runway
• Clear obstacles on climb
These may require different take-off techniques. To clear obstacles, it is not important to get airborne as soon as possible — the important thing is to accelerate to Vx as soon as possible. This may very well mean getting airborne later as the aircraft will (up to a point) accelerate faster on the runway than in the air (where induced drag will become a factor). Also, to get airborne as soon as possible you might need to use flaps, which will reduce the climb angle.
Also, in crosswinds and gusty winds generally, getting airborne early will increase the risk of an accident as controllability suffers at low speeds.
I still fail to see why that should be different on a soft field vs. a short field.
On a soft field you need to get weight off the wheels quickly to reduce wheel drag, so you will want to raise the nose early (and possibly use flaps). Again, this will likely increase the required field length as you need to spend more time in ground effect accelerating.
OK chaps, thanks for bearing with me patiently! I think I more or less understand.
As I understand it, I was taught the “soft field” technique as a standard, as we rarely fly from anything else; and if we do, the runway will be very long (say 600 metres or even more) so clearing obstacles is not an issue anyway.
the runway will be very long (say 600 metres or even more) so clearing obstacles is not an issue anyway.
Be aware of obstacles well beyond the runway if at max AUW, no wind, and warmer (+humid) than usual. On Saturday I did a T/O, and later was a pax on a T/O, where our rate of climb would not have been acceptable at some strips we use – we knew this when we planned the trip. Second runway 500M, but no obstacles for miles.
PS I believe the soft field technique for Cessna singles is very different from the Robin DR400.
At 8000 ft density altitude or similar you’ll likely be using short field techniques with a lot more than 600 m / 2000 ft runway length, double that would be good. Then climb out might be at 250 fpm in many types – hopefully towards lower ground.
