Unhappy with my soft field take offs

What aircraft do you fly? What you are referring to is ground effect, and lowering the nose to build up sufficient speed to enable a good climb out. I take off from a grass runway, and I would agree you have to be careful and quick to react to any wind changes that may dip a wing.

The other thing to do is, put your foot on the brakes and apply full power and let it build up before releasing the brakes. The other thing you can do, which I will be honest isn't a method I have needed to use myself, is to begin the takeoff roll without flaps to reduce drag, and then put them in a bit later. The 'bit later', I suspect is specific to the aircraft flown.

The other thing you can do, which I will be honest isn't a method I have needed to use myself, is to begin the takeoff roll without flaps to reduce drag, and then put them in a bit later. The 'bit later', I suspect is specific to the aircraft flown.

This is a technique I have never quite understood. The drag is low at low speed. In a soft field playing with the flaps while moving quickly strikes me as likely to induce more control problems than it solves. Does it really get you in the air much faster?

Does it really get you in the air much faster?

Hopefully someone can expand and clarify that :-) I guess it makes the takeoff roll more streamlined. To me it is marginal, and maybe it is aircraft specific too. My Uncle runs a skydiving centre in the US, and operates from a small grass strip with a C182, and he swears by the method. Then again his flying regime is to get to 14,000 quicker than a space shuttle, and to get down quicker than a Cirrus without a parachute. This is something that probably has more noticeable effect on Cessna's than Pipers (possibly).

If you do a "soft field" takeoff from a hard runway, the actual distance moved before you peel yourself up from the runway is about the same.

This is probably because of the high elevator drag trying to get the plane into ground effect early on.

On a real soft field you have to use that technique to get out of there; also it protects the nosewheel from hitting bumps at say 50-60kt which would not do it much good.

If you do a "soft field" takeoff from a hard runway, the actual distance moved before you peel yourself up from the runway is about the same.

Yup, that's why it is a "soft field" and not a "short field". A soft field takeoff will take much more distance on the soft runway, than a short field takeoff will take on a firm runway. If you do both a soft and short field takeoff on that firm runway, you'll probably get similar ground run distance, but the climb away following breaking ground will be less for the soft field takeoff.

A 152 is a lackluster soft field aircraft, because of the prop - it is optimized for cruise flight, not climb. However the technique is the same in any case.

You are not the least concerned about wing drop on a soft field takeoff, as your objective is to get off the ground, not away from it. Once airborne, the drag of the "soft" is over with, and you will accelerate the plane to a safe climb away speed as close to the ground as practical. If you got airborne with a stalled wing, who cares, as long as you are airborne. The worst is you stall the wing more, and settle on again with one dropped a little. Before you think that you cannot pick up the wing, check, have you tried full aileron? Yes, there is a drag rise with lots of aileron application, so don't unless you have to, but it is there to be used! (If the application and holding of full aileron in a 152 is uncomfortable to you, some more very slow flight practice is in order).

Just like a floatplane takeoff, I will begin the takeoff with lots to full aileron applied (into the crosswind if there is one). I will only roll off that aileron when one wheel has lifted off (out) a little. Like a floatplane your surface drag has instantly reduced by half when you do that, and you can feel it.

A soft field technique on a short runway is asking for trouble, unless the departure path is well clear for a long way.

The object is to get the aircraft into the air at the slowest possible airspeed, and stay in ground effect, until a safe flyaway speed is obtained. It works the same on any single engine, tricycle configured aircraft, which has a low, stabilizer/elevator tail. Stabilator and T tail aircraft usually have different characteristics, and require extra technique or skill.

Yes, full up elevator as you begin the takeoff, get the nosewheel off as early as possible, and hold it there, and be careful to not bang the tail on the ground. Though there are differing opinions, I find it pointless to set full power on the brakes, unless there are very specific engine operating requirements which require great pilot attention (not exceeding limitations) with the application of full power. You have zero airspeed, lots of propeller speed, so all of the propeller blade is completely stalled. You have to overcome that drag on the prop before it begins to work for you. I prefer to do a rolling takeoff out of the turn to runway heading. This is often a good idea, because if the ground is soft, the last thing you want to do is stop, or do a pivot turn on it! So get everything set, and your pretakeoff checks down on the backtrack!

The techniques I mention are not directly applicable to Piper Cherokees, Cessna Cardinals, Tomahwks or T tail Pipers. Those types have a number of hidden surprises waiting for you if you apply aggressive soft field techniques.

Instead of a 152, if you can find a 150, with a "climb" prop on it, you will get a better soft field takeoff result. Sometimes, the "old 150" at the club, which no one wants to fly, is really the better one! I did my first solo on the first 152 which came to Canada in 1977. Everyone wanted to fly it - more power! After I got used to it, I went back to the 150's quite willingly.

The trick with the flaps was to start the roll with no flap and full aft elevator. When you get near rotation speed you pull on 20deg of flap and the aircraft balloons off the ground. Then nose down in ground effect and accelerate, slowly raising flap. This only really works well with manual flaps, with a nice big lever. If you start the roll with 20deg a flap you add too much drag.

Be careful hauling off into ground effect whilst semi-stalled, with a more powerful engine you could get a big surprise as it tries to roll over. Be ready to apply a lot of rudder.

Rhino, to me it sounds as if you are doing well. Ailerons are sloppy at minimum airspeed, and for this technique to be applied, in my opinion, one's limitations for crosswind and gusty winds should be tightened a bit.

Don't fiddle with the flaps during take-off roll. "Popping" the flaps is a circus act and is both especially useless and especially distracting during a soft-field take-off. Set the flaps as required for maximum performance take-off and leave them until at a safe altitude. Also don't hold it on the brakes while applying full power. That is short-field technique and could result in digging three holes in a soft runway. Actually, a take off from a very soft field could call for entering the "runway" without stopping at all before applying take-off power, to avoid sinking in.

Soft-field take-off distance is something for which there is no meaningful way to calculate. For that reason it is necessary to determine beforehand when to abort the take-off. I use the following: if at the midway point, the airspeed is not 2/3 of Vx or more, I abort. This could be modified a little to take slope, braking friction and runway length into account, but the main thing is to have decided beforehand when to give up, and not keep dragging the airplane into the next field, or worse. And yes, I have aborted a short field take-off, if only once.

Night: I recommend against soft-field take-off's at night, especially in dark surroundings. Hanging in ground effect, trying to accelerate out of the stall with the landing light pointing to the sky and absolutely nothing to see outside - is not something I wish to do again. I did it during my CPL training in a C177RG, and neither my instructor nor myself had quite anticipated what it would be like.

Airplane types: a good power-to-weight ratio makes for a good soft-field-take-off performer. Low tire pressure is good also. Aerodynamics means nothing. For those reasons many motorgliders and the DA-40 diesel are poor. A Piper Dakota is quite good, a Bonanza not bad at all. Reducing weight works in favour of every take-off, but even more so from a soft field.

Flaps again: some single types do not prescribe flaps for the take-off, but most or all types benefit from a little (or some more) flaps for a soft-field take-off. However, some airplanes do have flap limitations for take-off. Mentioned Bonanza improves both soft-field and short-field performance significantly with approach flaps, although no mention of flaps for take-off is in the manual. The same goes for AA-5's and, I am sure, many others. I suspect it is about the cost of certifying and the sweat of working out more performance tables.

All though I agree that changing manually selected flap settings during the takeoff roll can affect takeoff distance favourably, I have two thoughts about doing it: The risks of loss of control probably outweigh any benefit for most pilots, and it is more likely that you'll get it wrong, and defeat the benefit, unless you're really experienced in doing it - in which case, you don't need to read here that you can do that.

Starting your roll with the flap extended, and leaving it that way, will increase drag early in the roll, at it increases lift too - which is why you're doing it!

If the soft field operations are so iffy that these tricks are making the difference between success and failure, you probably should not be attempting the takeoff in those conditions the first place!