Soft field takeoff

[Taracka]

Hello all,

  I'm in the process of transitioning to flying an m20c and would like advice on soft field takeoff technique.  In Cessnas it was normal to pull back on the yoke at the start of takeoff roll which allowed the nose to lift off the ground.  If I use this technique with the Mooney it seems to have no effect on nosewheel lift and just results in an extended takeoff distance.  What is the recommended yoke position for a mooney through the stages of a softfield takeoff.

Thanks,

     Rich

[AmigOne]

From somewhere in the internet:

Takeoffs and climbs from soft fields require the use of operational techniques for getting the airplane airborne as quickly as possible to eliminate the drag caused by tall grass, soft sand, mud, snow, etc., and may or may not require climbing over an obstacle. These same techniques are also useful on a rough field where it is advisable to get the airplane off the ground as soon as possible to avoid damaging the landing gear.

   Soft surfaces or long wet grass usually retard the airplane's acceleration during the takeoff roll so much that adequate takeoff speed might not be attained if normal takeoff techniques were employed.

   The correct takeoff procedure at fields with such restraining conditions is quite different from that appropriate for short fields with firm, smooth surfaces. To minimize the hazards associated with takeoffs from soft or rough fields, support of the airplane's weight must be transferred as rapidly as possible from the wheels to the wings as the takeoff roll proceeds. This is done by establishing and maintaining a relatively high angle of attack or nose high pitch attitude as early as possible by use of the elevator control. Wing flaps may be lowered prior to starting the takeoff (if recommended by the manufacturer) to provide additional lift and transfer the airplane's weight from the wheels to the wings as early as possible.

   The airplane should be taxied onto the takeoff surface at as fast a speed as possible, consistent with safety and surface conditions. Since stopping on a soft surface, such as mud or snow, might bog the airplane down, it should be kept in continuous motion with sufficient power while lining up for the takeoff roll.

   As the airplane is aligned with the proposed takeoff path, takeoff power must be applied smoothly and as rapidly as the powerplant will accept it without faltering. As the nosewheel type airplane accelerates, enough back elevator pressure should be applied to establish a positive angle of attack and to reduce the weight supported by the nosewheel. In tailwheel type airplanes, the tail should be kept low to maintain the inherent positive angle of attack and to avoid any tendency of the airplane to nose over as a result of soft spots, tall grass, or deep snow.

   When the airplane is held at a nose high attitude throughout the takeoff run the wings will, as speed increases and lift develops, progressively relieve the wheels of more and more of the airplane's weight, thereby minimizing the drag caused by surface irregularities or adhesion. If this attitude is accurately maintained, the airplane will virtually fly itself off the ground. It may even become airborne at an airspeed slower than a safe climb speed because of the action of "ground effect." This phenomenon produces an interim gain in lift during flight at very low altitude due to the effect the ground has on the flow pattern of the air passing along the wing. "Ground effect" is further explained in the chapter on Principles of Flight.

   After becoming airborne, the nose should be lowered very gently with the wheels just clear of the surface to allow the airplane to accelerate to the best rate of climb speed (Vy), or best angle of climb speed (Vx) if obstacles must be cleared. Extreme care must be exercised immediately after the airplane becomes airborne and while it accelerates, to avoid settling back onto the surface. An attempt to climb prematurely or too steeply may cause the airplane to settle back to the surface as a result of losing the benefit of "ground effect." Therefore, it is recommended that no climb to an altitude higher than barely clear of the surface be attempted at an airspeed slower than the best angle of climb airspeed (Vx).

   After a definite climb is established, and the airplane has accelerated to the best rate of climb speed (Vy), retract the landing gear and flaps, if so equipped.

   In the event an obstacle must be cleared after a soft field takeoff, the climbout must be performed at the best angle of climb airspeed (Vx) until the obstacle has been well cleared. After reaching this point the airspeed may then be accelerated to the best rate of climb (Vy) and the flaps and gear retracted. The power may then be reduced to the normal climb setting."

[Larrynoel]

I don't think I would use Mooney and soft field in the same sentence.  That is really not a good place to be...   Even with our older mooneys,  the nose is just too heavy, and gear as sturdy as it may be, a little too fragile to risk on a truely soft field.  Combine that with the prop clearance, it is a high risk operation in my book.    

I don't have a problem with grass, but if it is rough or soft,  I would be pretty hessitant.

With that disclamer out,  If the indigenous folks were after me with their spears,,,  I would focus on keeping the speed as fast as reasonably possible and try to balance bringing up the nose wheel.  Don't just lift off the wheel like a cessna, try to ease if up into the air.  It takes a little practice,  it seems to me if you try to pull the nose up too strongly, the plane does not accellerate or fly near as effectively.

Personally, I would wait for the field to dry..

 

craig

 

[clh]

Sorry Larry, that last post was me.

[Z W]

The short answer is not to land on a truly soft field.  It's the one area our planes really fall short.  That being said, there's nothing wrong with grass.  When taking off on a dry, level grass strip, I usually set my trim slightly more nose-high than usual, and other than that, takeoff as normal.  I trim up so the indicator is about a half or 3/4 of the bar above where it is marked "takeoff."  It gets the plane up on the mains a little faster, but be careful not to pull back into a power-on stall.  As soon as you're airborne the plane will be trimmed for a Vx climb.

You are correct you don't want to pop the nosewheel up like you would on a Cessna.  Also, take a look at how close your tail is to the ground while the plane is sitting level.  I'm not at all confident I could even ride a takeoff with the nose up without banging the tail.

[moodychief]

I did a soft field once.  Two pumps of flaps, apply enough back pressure to keep the front wheel skimming the ground as the controls become effective, slowly release back pressure when airborne to accelerate in ground effect, positive rate of climb, retract gear and trim for climb.

Wasn't worth the hour of washing the mud off!!!  Mud in wheel wells, step, belly, bottom of flaps, top and bottom of tail surfaces.  Never again.

ZANE:  BTW I went to High School in Camdenton.  Moved to Springfield my senior year.  Nice little town.

[Hank]

Rich--

Like the others have said, I fly my C into grass strips without any problem, but I avoid soft fields when I know about it. Last year, I delayed my departure from Sun-N-Fun to let the grass camping area firm up some before I taxied out, much less tried a soft field departure.

Remember, you only have 9" of prop clearance, and having the nosewheel dig into the mud can quickly reduce that.

My normal procedure when carrying a single passenger and light luggage is to put the bottom of the trim indicator even with the top of the "Takeoff" line, a little extra nose-up. When heavier, I put it right on the line; when operating near gross at home, or from grass, I use Takeoff flaps too, just to make sure I get up and over the trees.

My Owner's Manual has no information about soft-field operations, but does have this wonderful paragraph that clearly shows a difference between departure in a Mooney and in a Cessna, which is where I transitioned from, too.

As speed increases during the takeoff roll, apply back pressure on the control wheel at about 65 to 75 MPH. The aircraft will tend to rock into a nose-high attitude as it breaks ground. To compensate for this tendency, slowly relax some of the elevator back pressure as the nose wheel leaves the runway. Keep the nose on the horizon just after the aircraft breaks ground to allow smooth flight from the runway without an abrupt change in pitch attitude.

Maybe Piperpainter will chime in with some tips here. He is also in the Pac NW, flies a C model, and visits all kinds of backwood strips with his tailwheel friends. Look for his videos on Youtube. I can't say I would fly my Mooney everywhere that he takes his, but he is certainly skilled in the types of operations that you are asking about.

[WardHolbrook]

I like the comment about not using the phrase "soft-field" and Mooney in the same sentence. The Mooney wing is fantastic, it's one of the best designs out there - just about perfectly matched to the rest of the airframe. But...

It's probably not the airfoil of choice for serious "off roading" if you get my drift. The Mooney wing likes airspeed and it achieves its efficiencies when it's flying fast. Not all wings are like that, take for example the Clark Y airfoil that is found on a lot of "bush" planes like the J-3, Super Cub, and even some twins light the Apache and Aztec. It's pretty hard to coerce that airfoil to do anything fast, but it doesn't mind low speeds and relatively high angles of attack - that's one of the reasons that you see that airfoil on so many working airplanes. 

The Mooney wing isn't fond of low-speed, high AoA flight. It likes airspeed. You mix that with comparatively low prop clearance and landing gear doors that have a tendency to snag things (Read: can get bent and cost $$$ to fix or replace) and you see why it's probably best to not mention soft field and Mooney in the same sentance. If your mission description involves that type of flying it might be prudent to rethink your choice of aircraft. 

 

[Taracka]

Here's my situation.  I live on a 2400' grass strip which almost never gets soggy because it was designed well.  The problem is in some sections there is a slight bit of roughness that you'd never notice in a cessna but gets a little bouncy in the mooney.  I suspected the technique described by the previous posts was correct so I'll start using them.  

Thank You,

     Rich

[Hank]

I visit a 2000' grass field with the gravel pile from a cement plant at one end. I never go there heavy, and I certainly never try to depart heavy! All the way to the end, with the tail sticking out over the unmown area; set departure flaps; trim set slightly up, lines mismatched as described above; go to full throttle, release brakes, lift off at 65 MPH. Once positive rate is determined, gear up; raise flaps when above trees or gravel depending on direction.

If you can, roll the rough spots to smooth them out. Water makes an excellent weight that won't need transportation to and from the field.

I maintain just a little bit of up elevator to lighten the nose. Sometimes a bump will put me in the air below flying speed, keep wings level and set her back down, concentrating on directional control. Other Mooneys live on grass fields, I'm only an occasional visitor. Grass, yes; wet grass is messy to clean up; mud and yuck, no thank you, it will dry out in a day or two, and make for a safe, not-so-messy departure.

[jetdriven]

I have no problem with grass,  but mud or really soggy ground I would avoid.  For one, prop clearance as mentioned here is minimal. Another thing is that full up elevator causes the nose to pop up rather suddenly around 40 knots so careful to not bang the tail.  Another reason, is all that mud and dirt gets in your landing gear wells, landing gear pivots, and gear doors.  Allowing that stuff to stay in there can corrode the spar.  Smoth dry grass, however, is realy cool.

One more thing, I would recheck my landing gear preload before operating from grass. If it isn't just right, the gear can collapse.   The adjustment range is only a few thousandths.

[jlunseth]

Last summer I landed on all the grass strips in Minnesota except one.  That was 22 grass field landings.  The first fourteen were done with another pilot, we rented a 172 for the purpose. They felt easy and comfortable in the 172, so I did several more with the 231, including some landings on grass at airports that had asphalt, but I chose the grass.  So it was probably around a dozen with the Mooney on grass strips.  I learned several things in the process.  One is that most grass strips are really well maintained.  The surface is generally hard.  Unless you insist on landing in the morning where it rained the night before, there is little need for soft field technique, certainly not just because the strip is grass.

The other thing I learned was that my 231 did not like soft field technique on grass.  Soft field technique is to hold the yoke full back starting with the taxi onto the runway, and hold it full back during the start of the roll, until the plane leaves the ground in ground effect.  All the aircraft I have done this with, including my Mooney, then do what I call rolling over the hump.  As soon as the plane leaves the ground, the pilot relieves the back pressure on the yoke a little, enough to allow the nose drop to level and leave the plane in ground effect.  It feels like the plane has flown over a hump into ground effect.

Unfortunately, the 231 would not do that on grass.  It does that on asphalt, it flies "over the hump" and right into ground effect, but on grass it wants to stay in a very high angle of attack and relieving the pressure on the yoke puts it back on the ground.  That high angle of attack is very awkward, the plane is basically flying right at stall speed.  The best I could determine, on asphalt the plane picks up ground speed (and therefore also airspeed) quite quickly, and is ready to fly albeit in ground effect.  On grass, the friction causes it not to pick up much ground speed, so it does not fly very well at all.

The technique I came up with was a modified soft field, I don't go full yoke back, but do hold the yoke back somewhat to protect the nose gear.  I let the plane pick up some ground speed before I pull it into ground effect.  I don't do very many grass strips though, no need.

[Parker_Woodruff]

jlunseth,

Just a note - even in something like a Cessna 172, there is generally no reason to leave full backpressure on the yoke all the way to the point of liftoff at a soft field.  As soon as the nosewheel comes off the ground, it's a slow progression of releasing some of the backpressure on the yoke.  Your "modified" technique is actually pretty close to standard soft field technique.  It really doesn't require "pulling" the plane into ground effect.

[Oscar Avalle]

Thanks all those comments are extremely helpful. I have been flying more and more from grass fields and the mooneys are not that bad, as long as you follow the procedures.

[Taracka]

Thanks for all the input on this subject.  Very useful info and much appreciated.

     Rich

[FloridaMan]

Be ready to put in a fair amount of right rudder when you pull up into ground effect, otherwise you'll find that the Mooney will like to drift left of centerline at such low airspeeds and high power settings.