Soft-field takeoffs

[PHXAvi8tor]

Here's a question of "technique vs. POH":

In the Arrow (and probably many low-wing airplanes), the POH says to raise the landing gear soon after liftoff (before raising flaps) on a soft-field takeoff.

The reason they say to do this is to reduce drag.

However, many flight schools teach students to leave those gear down until end of usable runway is cleared.

Who's right? The POH is the legal document, so it cannot be debated. But, the schools are also right, for safety reasons.

You could argue that, if there's no obstacle to clear, then leave the gear down a bit longer until end of usable runway is gone. And, if there is an obstacle to clear, then get the gear up sooner to reduce drag and climb out at Vx.

So, what is your common practice on soft-field takeoffs? Gear up right away, or leave them down until end of usable runway?

 

[CJones]

I haven't flown any low-wing retract's, just the Cessna Cardinal RG. The POH for the 177RG says, if I remember correctly, to leave gear down until clearing the obstacle b/c the way that the gear retracts actually induces a bit of drag.

If I were shoved into a low-wing retract right now and had to perform a soft field takeoff, I would probably pull the gear up as soon as I was sure of not being able to make a straight-ahead touchdown on the runway, not necessarily after clearing the end of the runway. Chances are, if you're doing a soft-field t/o and you're having to clear an obstacle (I'm thinking trees, wilderness, rocks, etc.) then if you have a situation that you need to land immediately after departure, but can't do it straight ahead on the runway, then the gear probably won't do you much good anyway.

Just my .02.

-Chris

 

[tonycondon]

are you asking soft or short? in most cases i understand that the retraction cycle creates more drag than just leaving the gear extended so it would probably be gear down until obstacle clear.

ask EdFred about following POH on soft/short takeoffs.

 

[Ken Ibold]

I think you mean short field, not soft. In a soft field, the drag of the gear would not matter once you got off the surface.

If it's short enough to matter whether the gear is up or down, I would rather put the gear up and risk a belly slide in the event of an engine failure than leave the gear down and risk hitting the trees. But that's me. (In an Arrow, anyway. The drag penalty for retraction time is essentially nothing in an Arrow, although in other airplanes it can be substantial. In a Mooney, I would leave it down.) And by the way, this has nothing to do with high wing/low wing, but rather the type of geometry the gear goes through as it retracts.

 

[EdFred]

Thanks Tony.

For a checkride, follow the POH no matter what. For real life do what's appropriate and safe. I busted my checkride because I left the gear down even though we had usable runway left, and I stated that during the takeoff procedure.

 

[PHXAvi8tor]

Thanks Tony.

For a checkride, follow the POH no matter what. For real life do what's appropriate and safe. I busted my checkride because I left the gear down even though we had usable runway left, and I stated that during the takeoff procedure.

Ed, good advice!

That's the same advice I'm giving students and which I will be following when I do my CFI Initial checkride later this month.

PS: Some in this thread asked if I meant "short-field" takeoff. No. For the PA-28R-201 (Arrow II), the checklist for *soft* field takeoff specifically says that the gear should go up first, and then you can begin removing flaps. In many flight schools, the technique that is taught is different. The flight-school technique is: Flaps, Flaps, Gear, Flaps in that order.

Now, my flight bag is out in the trunk of the car and I'm too lazy to go out and dig it out right now. But, the POH may also say the same for *short-field* takeoff: Raise the gear first. I am pretty sure it does, but cannot swear by it without checking.

 

[Henning]

I'm assuming you meant short field, and in an Arrow, I'd "Positive rate, gear up" it.

 

[KennyFlys]

I've only flown the Skylane RG but I don't think I'd gear up any plane until I was positive on both counts.

Likewise, go with the POH on a ride but safety procedures count as well. Our Skylane will foul the plugs in no time if you leave mixture rich for long, especially at low speed or idle. So, except for take off and departure, it's back out a bit, even for run-up. Regardless of the POH, I'll have to make this argument on my commercial ride. Fortunately, the DPE has been in this plane for previous rides and will know. But, I still have to be ready to defend my position.

In the case of a gear issue on short of soft field departure, I'd probably bring up the question with a DPE and get his perspective. Just say you've heard both arguments and have a hard time balancing the POH with what would certainly seem a safe action.

 

[PHXAvi8tor]

I'm assuming you meant short field, and in an Arrow, I'd "Positive rate, gear up" it.

Affirmative on the "positive rate of climb," and I'd also verify "positive airspeed" (airspeed increasing to Vx).

Darn it, you're going to make me go dig out my Pilot's Information Manual regarding short- versus soft!

No, I am certain that the PIM says to raise the gear first for SOFT field.

I'll be back. Going to go get the PIM.

. . .

OK, I'm back with my torn and ragged-edged PIM in tow.

Here is the checkist procedure for "SOFT FIELD TECHNIQUE" found on page 4-11 (stuff in parentheses is mine):

Flaps: 25 degrees
Accelerate to 50 to 60 KIAS depending on aircraft weight (See Section 5 performance charts)

Control wheel: Hold back pressure to ROTATE to CLIMB ATTITUDE (hold it during taxi onto runway and during takeoff roll. Fly into ground effect, and stay level to let airspeed increase to climb speed.)

After breaking ground, accelerate to 55 to 65 KIAS depending on aircraft weight. (Again, see Section 5 performance charts)

Gear: UP
Accelerate to best gear up rate of climb speed - 90 KIAS.
Flaps: Retract slowly.

---

Now, here's the checklist for SHORT FIELD takeoff in the Arrow II:

Flaps: 25 degrees
Accelerate to 50 to 60 KIAS depending on aircraft weight
Control wheel: back pressure to ROTATE to CLIMB ATTITUDE
After breaking ground, accelerate to 55 to 65 KIAS depending on aircraft weight.
Gear: UP
Accelerate to best gear up angle of climb speed - 78 KIAS, slowly retract the flaps and climb past the obstacle.
Accelerate to best gear up rate of climb speed - 90 KIAS.

----

So, we can see from the PIM that for SOFT field (*not* SHORT field) the assumption is no obstacle clearance. That is because the PIM says to accelerate to best rate of climb speed, which is Vy, or 90 KIAS.

However, in BOTH short and soft field takeoffs, the gear would come up first -- before flaps, if we were to follow the PIM verbatim.

Flight schools will continue to teach, however, that if you have good landing terrain ahead, go ahead and leave the gear down until end of usable runway. However, you cannot go wrong in following the PIM/POH, either!

 

[PHXAvi8tor]

I've only flown the Skylane RG but I don't think I'd gear up any plane until I was positive on both counts.

Likewise, go with the POH on a ride but safety procedures count as well. Our Skylane will foul the plugs in no time if you leave mixture rich for long, especially at low speed or idle. So, except for take off and departure, it's back out a bit, even for run-up. Regardless of the POH, I'll have to make this argument on my commercial ride. Fortunately, the DPE has been in this plane for previous rides and will know. But, I still have to be ready to defend my position.

In the case of a gear issue on short of soft field departure, I'd probably bring up the question with a DPE and get his perspective. Just say you've heard both arguments and have a hard time balancing the POH with what would certainly seem a safe action.

Very good advice, Ken. Totally agree!

 

[MauleSkinner]

I don't have the answer, but you might consider this...For a soft-field takeoff, the object is to get the airplane in the air at minimum flying speed, possibly even below published Vso. This is HIGH DRAG.

Now, imagine that you're doing this out of a mountain strip on a warm day, with 4 people. Even at Vy, your airplane isn't going to climb like the proverbial homesick angel, and you're in a much higher drag configuration than you would be at Vy. You NEED to reduce drag in order to accelerate to a speed at which you can climb. You can't retract flaps, so the only thing left is the gear.

Unfortunately, the vast majority of our soft-field training is done off hard surfaces (asphalt, gravel, or sod) at weights and altitudes that allow for a fair amount of excess power. The airplane, however, isn't limited to the conditions under which we train, and so the manufacturer publishes the technique that will give the best performance under any conceivable circumstance. Safety issues are your responsibility, and if you don't think that the POH version is a "safe" way to go, you simply avoid situations where you'd need to use it.

You might also note that in a true soft-field takeoff, you're probably going to be running out of "useable runway" about the time you get airborne anyway.

Fly safe!

David

 

[poadeleted20]

The book is based on engineering input and flight test by qualified test pilots. If the book calls for raising the gear as soon as you have a positive rate of climb, that is the most effective method for performing the maneuver. If the flight school wishes to trade some effectiveness for improved safety, well, it's their airplane.

What's my practice? Follow the book, unless the airplane owner says otherwise, in which case either I tell the owner to find another pilot or I make sure there are added margins to allow for the reduced effectiveness of the demanded technique.

 

[Shipoke]

Well for what it's worth , i leave the gear down,but only cause i cant raise it (PA28-161 Warrior). But i think i'd leave it down till usable runway is gone.
Just my opinion, seems safer to me
Dave G.

 

[MauleSkinner]

Also, regarding the "useable runway" issue...

How many of you who would leave the gear down until you were out of useable runway would, in the event of an engine failure enroute, land gear-up in a muddy field for fear of digging in the nosewheel and flipping the airplane?

A soft field is a soft field

Fly safe!

David

 

[TMetzinger]

I think the issue is that with this technique, you've got a comparatively large amount of flaps in, creating both lift and drag. You want to accelerate (meaning you've got to reduce drag) yet NOT reduce lift - the best way to do that is to raise the gear. You'll gain energy so you can pitch up as you reduce the flaps to maintain a positive rate of climb.

Try it at 1000 AGL sometime - put the gear and 25 degrees of flaps down, pitch to your takeoff speed for short field, and then reduce the flaps while leaving the gear down. I bet you'll sink, and you'll be slow enough that you might stall if you increase pitch to compensate. That's also the reason they want you to take those flaps out slowly.

 

[gismo]

If the Arrow POH says to retract the gear ASAP, then that's probably the best procedure and the POH takeoff distances are probably predicated on following the specified procedure.

But that's for the Arrow, there is no generic formula for this that applies to all airplanes or even all low wings. For instance, IIRC the Beech Bonanza requires that you leave the gear down untill clearing all obstacles and achieving a specific IAS because during retraction there is a noticeable loss of lift when those big gear doors open. IOW raising the gear when low and slow could cause the plane to settle back to the ground.

As to leaving the gear down until beyond the "usuable runway", I think that concept gets overplayed. Chances are that if you climb out at Vx or even Vy, you'd pass over a fair chunk of runway to descend and land once you've climbed a hundred feet. And from a couple hundred feet there's plenty of time to lower the gear if the engine quits.

 

[CowboyPilot]

In the Saratoga I used to own, I would get the gear up as soon as practical on a short-field takeoff. Didn't do any serious soft-field work in it. There was no real additional drag induced during gear retraction. On grass fields and/or fields that were a little soggy, I would get into ground effect as soon as possible and once stable, retract the gear then begin my flap retraction and climb.

In the CardinalRG, you don't do soft-field t/o's and landings--not if it's your airplane and you have a choice. But for short-field work, I leave the gear down until my Vx is nailed and everything is stable and I've cleared the EOR obstacles.

Three reasons for this: Ground effect is virtually nil in a high wing fast mover like this Cardinal that's been STC'd for a turbo. So in high DA short fields, I still have right good performance power for takeoff and I'm gonna use it all on a short-field t/o.

Second, during retraction, you get some noticeable drag. I'm not one for cutting margins to the slimmest tolerances, but if I've learned anything in 30 years of flying it is to do everything the same way everytime unless you have one helluva good reason to do otherwise. So I practice the way I intend to fly and that is leaving gear retracted until cleared of runway and obstacles.

Third, in the Cardinal, you get a noticeable CG shift during gear retraction. It's a variable that I can control in a busy cockpit such as during a short-field takeoff. So, I keep the gear down until I'm stable and comfortable.

Regards.

-JD

 

[MauleSkinner]

If the Arrow POH says to retract the gear ASAP, then that's probably the best procedure and the POH takeoff distances are probably predicated on following the specified procedure.

...except that manufacturers don't publish takeoff distance data for soft field takeoffs...there's just too much variation in surfaces to be able to do that.

What you see in your POH as a correction for sod, turf, grass, or whatever they call it, isn't soft-field distance...it's still predicated on the use of the same short-field technique.

Fly safe!

David

 

[AirBaker]

I'm assuming you meant short field, and in an Arrow, I'd "Positive rate, gear up" it.

I was looking for that answer too...

 

[NC Pilot]

In the Saratoga I used to own, I would get the gear up as soon as practical on a short-field takeoff. Didn't do any serious soft-field work in it. There was no real additional drag induced during gear retraction. On grass fields and/or fields that were a little soggy, I would get into ground effect as soon as possible and once stable, retract the gear then begin my flap retraction and climb.

In the CardinalRG, you don't do soft-field t/o's and landings--not if it's your airplane and you have a choice. But for short-field work, I leave the gear down until my Vx is nailed and everything is stable and I've cleared the EOR obstacles.

Three reasons for this: Ground effect is virtually nil in a high wing fast mover like this Cardinal that's been STC'd for a turbo. So in high DA short fields, I still have right good performance power for takeoff and I'm gonna use it all on a short-field t/o.

Second, during retraction, you get some noticeable drag. I'm not one for cutting margins to the slimmest tolerances, but if I've learned anything in 30 years of flying it is to do everything the same way everytime unless you have one helluva good reason to do otherwise. So I practice the way I intend to fly and that is leaving gear retracted until cleared of runway and obstacles.

Third, in the Cardinal, you get a noticeable CG shift during gear retraction. It's a variable that I can control in a busy cockpit such as during a short-field takeoff. So, I keep the gear down until I'm stable and comfortable.

Regards.

-JD

JD, Absolutely right. the correct answer is it depends. The drag on the Cessna RG's (and Mooney's too) is very noticable during the retract cycle. Also, don't forget the Cessna RG's landing gear drop during the retract cycle and you can drag the wheels if you are too quick with the gear lever.
Follow the POH and don't do like one Bo pilot did and move the retract switch to the up position before taking the runway so the wheels retract as soon as the squat switch makes after rotation.

 

[SCCutler]

JD,
Follow the POH and don't do like one Bo pilot did and move the retract switch to the up position before taking the runway so the wheels retract as soon as the squat switch makes after rotation.

Naw, really, someone *did* this? He maybe expected no bounces on t/o roll?

Darwin's theories at work.

 

[gismo]

...except that manufacturers don't publish takeoff distance data for soft field takeoffs...there's just too much variation in surfaces to be able to do that.

What you see in your POH as a correction for sod, turf, grass, or whatever they call it, isn't soft-field distance...it's still predicated on the use of the same short-field technique.

Right. I was thinking short field. Still, I'd go with the POH technique unless I had definitive proof that something else worked better. I would expect that the POH procedure was based on some sort of emperical testing.

 

[gismo]

In the CardinalRG, you don't do soft-field t/o's and landings--not if it's your airplane and you have a choice.

Why not? It's been a while but I recall having little trouble getting in and out of a fairly short muddy field in the C177RG I used to fly. I thought the main gear was pretty robust.

Second, during retraction, you get some noticeable drag. I'm not one for cutting margins to the slimmest tolerances, but if I've learned anything in 30 years of flying it is to do everything the same way everytime unless you have one helluva good reason to do otherwise. So I practice the way I intend to fly and that is leaving gear retracted until cleared of runway and obstacles.

I assume from the rest of your comments that you meant extended, correct?

 

[CowboyPilot]

I assume from the rest of your comments that you meant extended, correct?

Absolutely.

I must've been thinking like that Bo driver Mark mentioned. . .

Regards.

-JD

 

[NC Pilot]

Naw, really, someone *did* this? He maybe expected no bounces on t/o roll?

Darwin's theories at work.

Yep, told to me by a trusted CFII friend who was giving a BFR to a Bonanza pilot. The pilot said that was the way his flight instructor taught him.

He had the pilot taxi back, got out of the plane and refused to sign his log book.

 

[MauleSkinner]

Yep, told to me by a trusted CFII friend who was giving a BFR to a Bonanza pilot. The pilot said that was the way his flight instructor taught him.

He had the pilot taxi back, got out of the plane and refused to sign his log book.

Well, how else are you going to know if the squat switch actually WORKS?

Fly safe!

David

 

[poadeleted20]

Yep, told to me by a trusted CFII friend who was giving a BFR to a Bonanza pilot. The pilot said that was the way his flight instructor taught him. He had the pilot taxi back, got out of the plane and refused to sign his log book.

I think that's a bit extreme, as well as illegal. The illegal part is that an instructor must sign the log of anyone to whom that instructor gives training, whether the result was satisfactory or not. I can understand not signing the flight review endorsement, but not refusing to sign the log. However...

...before I got to that, I think I would have had the pilot shut down and go inside with me for a "come to Jesus" meeting about the wisdom of the technique that pilot's original instructor had taught him. If he truly saw the light (and maybe did a few backflips down the aisle of the church, a la Jake Blues), I'd get back in the plane and we'd do the whole thing over using proper technique, after which a successful performance would earn a flight review endorsement.

 

[JustinPinnix]

I think that's a bit extreme, as well as illegal. The illegal part is that an instructor must sign the log of anyone to whom that instructor gives training, whether the result was satisfactory or not. I can understand not signing the flight review endorsement, but not refusing to sign the log. However...

...before I got to that, I think I would have had the pilot shut down and go inside with me for a "come to Jesus" meeting about the wisdom of the technique that pilot's original instructor had taught him. If he truly saw the light (and maybe did a few backflips down the aisle of the church, a la Jake Blues), I'd get back in the plane and we'd do the whole thing over using proper technique, after which a successful performance would earn a flight review endorsement.

That would make for an interesting logbook entry:
0.1 hours dual - taxiing - Joe Instructor

 

[supercub185]

Is this a trick question? An arrow can not do a short or real soft field takeoff.

 

[flyingcheesehead]

Naw, really, someone *did* this? He maybe expected no bounces on t/o roll?

Darwin's theories at work.

I am pretty darn sure that Dr. Bruce had a student do this to him.

 

[poadeleted20]

That would make for an interesting logbook entry:
0.1 hours dual - taxiing - Joe Instructor

The regs require the logging of ground as well as flight instruction.

 

[jesse]

Soft field it's not going to matter.

Short field is another story...

I would do whatever reduces the amount of drag. It might even vary per field. It's possible that retracting the gear could increase drag for a short amount of time but the tradeoff will be by far less drag which could easily outweigh it.

There is no right answer.

It varies per airplane and airport.

 

[CowboyPilot]

Soft field it's not going to matter.

Actually, in some airplanes--like the Saratoga I used to have--when I'd take off from a mushy or muddy strip, I'd leave the gear down a bit longer to blow off all the mud and grass and muck. Saved my wife from having to get down underneath the airplane on a creeper and clean that stuff out of the wells once we got back home.

Regards.

-JD

 

[MauleSkinner]

Soft field it's not going to matter..

Never, ever, under any circumstances, huh? Fly safe!David

 

[Michael]

The "Johnson Bar" in my mooney makes it easy to retract and extend very quickly. That being said I have no problems retracting before useful runway runs out. I can have it back down in no time if needed. However a motor driven gear will be alot slower, and most likely take up the remaining runway waiting for it to extend.

 

[jesse]

Never, ever, under any circumstances, huh? Fly safe!David

It depends. Most soft fields are short fields too. I can see a reason to leave it down to try to fling off some mud but that wasn't exactly the topic being discussed.

Personally I fly all of my takeoffs short field. I don't see a reason to waste runway because it's not like you get to pick when something fails.

 

[CowboyPilot]

It depends. Most soft fields are short fields too.

AND. . . many soft fields become short fields once they get a little soft and mushy.

Is that your Skyhawk in your avtar? Hadn't been over here in a while and heard how your flying was going. Last time I was here, I was trying to lobby everyone to kick in a hundred bucks so we could put down a down payment on that Stinson.

Regards.

-JD

 

[EdFred]

The "Johnson Bar" in my mooney makes it easy to retract and extend very quickly. That being said I have no problems retracting before useful runway runs out. I can have it back down in no time if needed. However a motor driven gear will be alot slower, and most likely take up the remaining runway waiting for it to extend.

Humps also help too, don't they?

 

[Dave Krall CFII]

Three reasons for this: Ground effect is virtually nil in a high wing fast mover like this Cardinal that's been STC'd for a turbo. So in high DA short fields, I still have right good performance power for takeoff and I'm gonna use it all on a short-field t/o.


-JD

JOOC:
I've never found ground effect in any plane, high or low wing to be anywhere near the "one wing span" distance from the surface that I've heard of since day one flying. Where does that old "rule" come from?

 

[Michael]

Humps also help too, don't they?

Why I outta.....
Actually humps would be a good thing if every airport had them at the same spot.