Hold Brakes for Short Field Takeoff?

[201er]

For the shortest possible ground roll do you turn onto the runway from the taxiway applying power as you straighten out? Or do you align yourself on the runway, hold the brakes, full power, release? Which one actually gets you off shorter?

I can see the benefit of deveoping maximum thrust before rolling but I also see value in having a few mph going into it.

[GeorgePerry]

Quote: 201er

For the shortest possible ground roll do you turn onto the runway from the taxiway applying power as you straighten out? Or do you align yourself on the runway, hold the brakes, full power, release? Which one actually gets you off shorter?

I can see the benefit of deveoping maximum thrust before rolling but I also see value in having a few mph going into it.

[Shadrach]

http://www.avweb.com/news/pelican/182089-1.html

 

Deakin suggests that the technique depicted in George's Option A. powerpoint may result in a shorter take-off roll, but that it's so close as to be splitting hairs. He goes on to explain that there may be other benefits to "rolling" onto the runway...

"Tests have shown there is very little difference between stopping, then going to full power with brake release, or rolling onto the runway at a normal taxi speed, and turning onto the takeoff heading while going to full power. If anything, the latter will produce slightly better performance, and will certainly save your prop from dings and nicks from the gravel and dirt that often goes with the short runway."

[1964-M20E]

I was taught to hold the brakes, 100% power scan instruments then go.   I think the most important part of this is scan the instruments early to reasonably assure that you will not have any engine problems during takeoff since you are operating on a short runway and do not have a lot of margin.  Being from flat land here in the SE I do not consider anything longer than 2500 feet, even on the hottest day, a short runway but that will vary at higher airport elevations and higher DAs.

[johnggreen]

The relevant issues have been addressed and George broke it down well.  I will add only two thoughts, one already mentioned.

First, if you are in a situation where the small difference in rolling start, hold brakes full power, and reasonably increase of power on the roll makes a difference, you screwed up when you landed on a field too short for a safe departure.

Secondly, the damage to the prop is a real concern.  I have seen people who hold brakes and run their engines to full power for every take off, especially in a twin.  If you do this, I think you should monitor prop erosion; it will be significant and if you do it over some loose sand (that you probably can't see) will be evident from only one event.

Just my observations.

Jgreen

 

[PTK]

This is interesting John. You are saying that being able to land on a runway of a given length doesn't necessarily mean you'll also be able to take off from the same runway? I wonder if there is a way to establish a "critical" runway length. A length at which you can land and takeoff and anything shorter you can land but not takeoff. I guess there would be too many variables. Not the least of which being DA and temp considerations.

[Parker_Woodruff]

Quote: allsmiles

This is interesting John. You are saying that being able to land on a runway of a given length doesn't necessarily mean you'll also be able to take off from the same runway? I wonder if there is a way to establish a "critical" runway length. A length at which you can land and takeoff and anything shorter you can land but not takeoff. I guess there would be too many variables. Not the least of which being DA and temp considerations.

[Hank]

Per my Owner's Manual, using gross weight and standard temps:

sea level, 59º:  Takeoff = 1395'; Land = 1550'

2500 msl, 50º:  Takeoff = 1760'; Land = 1620'

5000 msl, 41º:  Takeoff = 2300'; Land = 1705'

The Takeoff distance becomes longer than the landing distance rapidly as altitude and temperatures [i.e., Density  Altitude] increases. Another factor to consider is weight. These are for landing at Gross Weight, but I have done that very, very infrequently; I do, however, make gross weight takeoffs from time to time. That will effective shorten the landing distance.

Oh, yeah, this is for dragging the wheels through the 50-foot-tall treetops on landing, and skimming the belly on the same branches on departure. since I don't do that, all of my required distances are longer than these book values!

I'm in the "hold brakes, full power, release" camp for short fields, and I try not to land somewhere that I cannot depart from.

[jetdriven]

Even airlines dont say which one has a shorter takeoff roll. We did both in the CRJ and the 1900D.  As George said, both techniques have advantages. I think that holding the brakes, giving it hell, and then releasing is shorter, however, I have no data.  It is a guess.

[201er]

Quote: GeorgePerry

Option B - Uses 100% of the runway.   Puts no side loads on the gear.   Is easier since the plane starts its' takeoff roll aligned with the runway.  The engine can be run up to 100% power and the pilot can check all the engine instruments, before ever moving forward. 

My personal opinion and preference is - Option "B".  Arguably safer and easier.   And before anyone says it...Yep I'm a Power Point geek.

[MARZ]

Quote: Parker_Woodruff

 The performance tables in section V of your POH.

[jetdriven]

Now we are really splitting hairs.  You cannot lock one wheel and spin an Mooney around for a "tail over the grass" takeoff as you can in a 172, but with a 32 foot turning circle, you can still put the rear edge of the rudder within ~10 feet of the first brick. 

[N33GG]

Off-airport pilots have long understood that just because you can land in a given distance, it doesn't mean you can take off again. Lots of factors come into play on take-off that simply aren't factors on a landing.

I'm with the 'hold the brakes and give 'em hell' crowd, and I can say (with lots of small remote strip experiences to validate this claim) that pulling a 180 on the backtrack to maximize runway length is a ridiculously simple manuever. One should have no trouble getting within 10' of the threshold.

[jetdriven]

Most airplanes can land and stop in less distance than they can take off.  Hank, I landed and stopped my J in 900 feet from the first brick with 5 people in it and at aproximately 2400#.   sea level, 75 degrees.  72 MPH over the fence.

[201er]

When a runway is short enough to be worrying about it, it usually isn't wide enough to back taxi and 180 a mooney on! I regularly fly to an airport that is 1950x50. I can't turn around on that runway. I buy gas there so I'm taking off near gross (100 gallon tanks) even in the summer. I can't turn around on the runway. So it's either turn on from taxiway and go or turn on and waste about 100ft getting straightend out to stop/hold brakes. Is the 100ft wasted justified with the extra thrust of full power with brakes? I have a hard time believing so, yet instructors keep making me do it that way.

[Cris]

Quote: jetdriven

Most airplanes can land and stop in less distance than they can take off.  Hank, I landed and stopped my J in 900 feet from the first brick with 5 people in it and at aproximately 2400#.   sea level, 75 degrees.  72 MPH over the fence.

[Hank]

Byron--

The book numbers I posted are from the theoretical 50-foot obstacle to stop, they are not roll-out distances. Your POH should be written the same way.

Mike--

It should not take you 100' of runway length to pull out to the center and line up! At my home field, 3000 x 75, I can do a full 180 and line up on-center in 50-60' or less. If you are worried about losing runway distance, swerve left before turning right onto the centerline [or vice-versa]. There are times when a tight turnaround is required, like 2770 x 40, no taxiway, just an exit to the ramp in the middle, so slow down, edge one wheel into the grass just past a light, give it some power and full rudder, add a touch of inside brake after pulling up onto the pavement. Full UP throughout. Often the narrow runways have a slightly wider bump at the end to turn around on if there's no taxiway.

One thing to do is check which way you can turn tightest. For whatever reason, my plane is easier to turn around to the right than to the left. I know this because we have no taxiway and the only exit is 1000' from the typical approach end; when the wind is wrong, I can easily make the turnoff with light braking, but normally coast past it before touching the brakes, then turn around and back-taxi. Left is a much wider turn than right.

[N33GG]

Someone got hit with the login bug... that is not my post above.

This thread has been beaten pretty well.  My only comment I will add to this topic is that if you are flying a turbo aircraft, you probably want to apply brakes, power up at least until the turbo is operational, and then go forward (I guess an exception would be if you taxi with enough power to get the turbo spinning :-)  ).  This is especially true in a twin.  The last thing you want in a twin, short field or not, is to apply  throttle, begin accelerating forward, and then have one turbo kick in and not the other.  You will possibly depart the runway before you realize what has happened.  I know, Mooneys are not twins, but people are here to learn.

For singles, Mooneys included, on short fields, I recommend holding brakes and adding enough throttle to confirm the turbo is compressing and working normally, and then begin rolling.

As always, just my two cents.

[PTK]

Quote: Parker_Woodruff

 The performance tables in section V of your POH.

[PTK]

Quote: Hank

Per my Owner's Manual, using gross weight and standard temps:

sea level, 59º:  Takeoff = 1395'; Land = 1550'

2500 msl, 50º:  Takeoff = 1760'; Land = 1620'

5000 msl, 41º:  Takeoff = 2300'; Land = 1705'

The Takeoff distance becomes longer than the landing distance rapidly as altitude and temperatures [i.e., Density  Altitude] increases. Another factor to consider is weight. These are for landing at Gross Weight, but I have done that very, very infrequently; I do, however, make gross weight takeoffs from time to time. That will effective shorten the landing distance.

Oh, yeah, this is for dragging the wheels through the 50-foot-tall treetops on landing, and skimming the belly on the same branches on departure. since I don't do that, all of my required distances are longer than these book values!

I'm in the "hold brakes, full power, release" camp for short fields, and I try not to land somewhere that I cannot depart from.

[jetdriven]

Hah, no.  Typo.  It was 3 people in a J.

Quote: Cris

 Ok i'm curious as to how you got five folks into a J model Mooney Did you have a fifth seatbelt? Or maybe a baby on Mom's lap?

[jlunseth]

This is probably germane only to 231 owners, but I use the "hold the brakes" method for a couple of reasons.  The primary one is that in a 231, and especially in the intercooled models, you can't just firewall the throttle, you will overboost.  So there is some management of the throttle that needs to happen at takeoff.  With a nice long runway it is no big trick to do this as you proceed down the runway.  But if you want full power for takeoff, best do it sitting still.  You need to put in some throttle, let the turbo kick in (which increases the MP quite a bit) and then inch the throttle up to max. MP.  I use 35", some people use 36" I understand. 35" is better for short fields though, because the MP needed to produce 100% HP increases as the plane picks up speed and two things happen, there is airflow over the intercooler which increases its cooling ability, and the motion of the aircraft "helps" the prop a little, reducing the load on the engine.  So at 35" I have a little bit of a margin built in to let these things happen during takeoff without producing a dramatic overboost.

The other is that this is not that hard on the brakes.  If you hold them, they are not rubbing, sovery little wear going on.