Flying in the Step to increase cruising speed

[Skybrd]

Flying in the step is something I believe to increase cruise speed. It appears to me that there are two ways to maintain altitude and cruise at a certain power setting. One is a more positive pitch setting that will maintain altitude and lower cruise speed. The other and prefered to me is to have a less pitch setting that will maintain altitude and provides a optimum faster cruise speed. In my opinion, to climb slightly higher than desired altitude, reduce pitch to level off, reduce power and let airspeed increase. This will cause a slight loss of altitude but a good cruise speed. At the desired altitude reset trim and increase power if needed to keep the altitude.  I don't think it works as well in turbulant air but ok in smooth air.

[PilotDerek]

Agreed. My complex check out instructor suggested the same thing. Climb a little above your intended altitude, then put the nose down, increase airspeed, then level off at intended altitude. He liked to get to cruise speed faster. His method does indeed do that.

[Hank]

"Flying on the step" . . .

works well when departing from smooth water--your airspeed will build up much quicker.

Trying to use this aviation myth in cruise, all it does make a shallow dive back to the proper altitude, and the descent accelerates you to cruise speed a little bit quicker. Your cruise speed will be the same. [Try it, and check five minutes after leveling off from your "on the step" descent.] To maintain the higher speed, you have to maintain the descent.

Mooneys fly at faster speeds when loaded more towards the tail. The further forward your CG is, the more downforce the elevator has to create, and that makes for additional drag. Load luggage in the back and see the difference. Just double-check your CG calculations.

"Flying in the step" is nothing but a myth. High-drag aircraft accelerate noticably quicker in the shallow dive; Mooneys accelerate pretty well when levelling off without a 300-500' dive back to cruising altitude. Even my low-powered C reaches final cruise speed pretty quick.

[jetdriven]

What you are seeing is the drag bucket that is a characteristic of laminal flow wings, such as a Mooney. The step myth was from one of the first laminar flow aircraft, the B-24, which was often so heavily loaded it often could not accelerate to cruise speed. So aircrews would climb 300 feet above cruise altitude, and then accelerate into the drag bucket. 

We busted this myth in a Cardinal RG, back in 2000.  Start timing exactly at level off and end it when you reach final cruise speed.  This takes a couple minutes.  Then start timing as you climb through your cruise altitude , stop climb 300' above, then descend to cruise altitude.  Its the same.

 

Hank is right, this plane loves an aft CG.

 

[FlyDave]

Quote: Hank

Mooneys fly at faster speeds when loaded more towards the tail. The further forward your CG is, the more downforce the elevator has to create, and that makes for additional drag. Load luggage in the back and see the difference. Just double-check your CG calculations.

[Hank]

One other comment--

When you reduce pitch to level off, don't reduce power until after the plane accelerates. At least, that's what my Owner's Manual says to do. Reducing power before acceleration, as you indicated, just makes it take longer. That's why you feel the need to dive.

-Climb at WOT/Max RPM

-Level Off at desired altitude

-Accelerate

-Set Cruise Power [my book says "upon reaching cruise altitude, allow acceleration to cruise airspeed, then trim the aircraft for level flight, reduce manifold pressure and RPM to desired cruise power."

-Lean per whichever paradigm you prefer.

[PilotDerek]

Quote: jetdriven

We busted this myth in a Cardinal RG, back in 2000.  Start timing exactly at level off and end it when you reach final cruise speed.  This takes a couple minutes.  Then start timing as you climb through your cruise altitude , stop climb 300' above, then descend to cruise altitude.  Its the same.

 

[jlunseth]

Well, here is one that does work, although not for cruise that I know of, and maybe only in my particular model, the 231.  I was taught it by a very good Mooney instructor.

When doing a climb to cruising altitude, level off at some point,say around 3-5,000, and let the aircraft speed up.  Leave it at 100% power full rich.  Once the speed has leveled off, pitch up for your climb.  You will find the climb will be at a significantly higher airspeed, in my plane between 105 and 120 knots, as opposed to 96 if you start the climb at Vy. 

In my experience, this does not last all the way up into the flight levels, if I am going to FL210 or higher the airspeed will start to drop somewhere along the way around 19 or 20, and the difference between this method and a straight Vy climb becomes insignificant, but from the point of the level off up to 19 or 20 airspeed will be higher.

Now, maybe if you have a machine like the Bravo or Acclaim that has lots of power this is not a help.  It is in the 231.

[Hank]

Quote: FlyDave

Hank,

What kind of speed increase do you see with an aft loaded CG?

I've flown with an aft loaded CG but didn't like the way the airplane felt. I'll start a new thread on this as I think it warrants additional comments.

Dave

[Hank]

Quote: jlunseth

When doing a climb to cruising altitude, level off at some point,say around 3-5,000, and let the aircraft speed up.  Leave it at 100% power full rich.  Once the speed has leveled off, pitch up for your climb.  Now, maybe if you have a machine like the Bravo or Acclaim that has lots of power this is not a help.  It is in the 231.

[Becca]

Oh, how I love debunking myths.  http://www.avweb.com/news/airman/184274-1.html

Just test out your theory - make sure to control all the variables (use the same altitude, heading for each on the same day, makes sure you close your cowl flaps at the same time for each, or just leave them open for the purposes of this trial). Have a passenger record altitude, groundspeed and TAS at 10 second intervals during the entire process (pre-prepare a table) and then at 1 minute intervals for the following 10 minutes after you level out:

1.  Attempt flying in the step, including reducing your power/mixture as soon as you reach your cruise altitude to cruise settings.  

Descend at least 2000' and then try the second option.

2.  Climb and level off the correct way.  Climb to 3500' exactly.  While at full power, mixture, level off and allow yourself to accelerate.  Once the acceleration is complete, then reduce your power/mixture to the same cruise settings you used in your first trial.

Average your TAS and Groundspeed for each trial, and I suspect you will find they are exactly the same.

[Lood]

There ain't no such thing as a step. No matter what you do, once you leave everything alone, your airplane will return to the altitude it was trimmed for and the speed will be the same. As for climbing past your target altitude, I'm not sure if that's worth it. If I take my F as example let's say we climb to a target altitude of 8000ft.

If I chose to climb to 8300ft at 500ft/min, that extra 300ft would take another 36 seconds. That 36 seconds is almost the same amount of time it takes to speed up from climb speed, which is 120mph IAS, to cruising speed, which is around 135mph IAS in my Mooney. I'm not sure how much speed one would gain on top of the 135mph IAS cruise speed during the small descend back to 8k ft, but I'm pretty sure that things will turn out even.

I think this might work with slow airplanes that struggle to fly fast, but Mooney's are too effecient...

[BorealOne]

Quote: Hank

"Flying on the step" . . .

works well when departing from smooth water--your airspeed will build up much quicker.

[Hank]

The prop is just fine, thank you. The whole trick is getting sufficient flotation from the itty bitty tires, since I haven't figured out the trick of retractable floats . . .

[jetdriven]

IF the step exists, then all those airlines, and corporate jets and turborpops are doing it wrong.  If there was a way to save ten pounds of fuel a leg in a jet, they would do it.  That would be hundreds of millions annually.

[johnggreen]

I've known some very old and very fine pilots swear by "the step".  Guys that had 20,000 plus hours in the log book in everything from DC-3's and J-3's to corporate jets.  I've tried to duplicate it in a multitude of airplanes and after everything settled down, there was no difference in cruise speeds.

A few years ago one of the av mags did a "test" and they couldn't show any advantage in "the step".

Rear CG can be dangerous if conditions change quickly and it's just not worth a couple of knots.  Fly safe and get there 90 seconds later.

[N33GG]

Flying on the step... hadn't had this conversation in a while.  BAH HUMBUG - there be no step, say I!  I needed a good laugh.  Yes, you can go a little above your target altitude and dive to get the pitch power drag combination for proper cruise.  Or you can level off, let airspeed increase, and the plane will find the same combination quickly, just like Hank said.  Only exception might be if you want to fly around with high pitch/ high drag for slow flight practice.  But if you never noticed, it takes some work to keep the plane in that mode, as with every slight change in pitch, the plane is naturally seeking the lowest drag solution given the power setting. 

As far as rear cg, the plane gains speed any time you can reduce induced drag (result of surface generating lift, whether up or down).  Get the cg to a point where the elevator is at neutral lift, niether up or down, and the induced drag is minimum, and the airplane cruise speed increases.  I used to fly a Piper Saratoga that would easily gain 10 knots with about 100 pounds in the rear, if I was flying alone with an otherwise forward cg.  With my short body C model, I haven't noticed much difference, maybe a few knots at the most.

 

[Skywarrior]

"The Step" is any speed above slow flight.

Chuck M.

[N33GG]

Quote: Skywarrior

"The Step" is any speed above slow flight.

Chuck M.