How Soon to Retract Gear?

[carusoam]

Too soon...

[231Pilot]

Once I have a positive rate of climb established, the gear comes up.  When the plane is clean, it climbs better, flys faster, puts more distance between me and terra firma.

[231Pilot]

Once I have a positive rate of climb established, the gear comes up.  When the plane is clean, it climbs better, flys faster, puts more distance between me and terra firma.

[aviatoreb]

Quote: Mazerbase

The gyroscopic force generates stress on the bearings and structure of the main landing gear only since the nose gear retracts in line with the rotation.  Not being able to brake the nose gear is irrelevant since the gyro effect are nill.  There is still the slinging of foreign material to consider.  I'm not sure how significant the stress is at our takeoff speeds but why add any unnecessary stress?

[John Pleisse]

"Positive Rate"....You guys have been reading the PTS and cleaning up after too many stalls in the practice area. We're not passing through V2 to Vmc.....use your noggin. Allowable runway.

[David Mazer]

The side loads of landing are something we strive to avoid.  The probability that we won't completely succeed is why the gear is designed to tolerate some but why inflict any that we can avoid with a simple tap of the brakes?  I don't know how significant it is for us.  I'm certain takeoff speed and the mass of the tire are the relevant factors but, also, the faster the takeoff and greater the mass the stronger the gear.  It may never be relevant.

However, even if it only prevents slinging slush/mud into the gear housing that may cause gear extension problems, it is probably worth it.

[airfoill]

Quote: aviatoreb

[Shadrach]

Like most subjects this one lends itself to differing opinions on what is best practice.  However, I'm not understanding the contention regarding "positive rate"... It's usually immediate in most Mooneys (including G models ) unless your say doing a soft field take off or departing Albuquerque in August at MGTW...

[John Pleisse]

Quote: fantom

 ....your right arm stronger, and you wing dip just after take off  Some folks still love  also

[aviatoreb]

Quote: airfoill

[Hank]

Once I know I'm flying, not bouncing, and that I'm staying up not floating in a gust, the wheels come up. sometimes I remember to tap the brakes, often I don't.

There was a trainer at the field with a grease spot on its white wheel, very visible during takeoff. The tire had completely stopped spinning in less than 3 seconds after liftoff--the big greasy spot was quite visibly still. That's when I quit obsessing about hitting the brakes.

As soon as I know I'm flying and climbing, the gear comes up. Most takeoffs are Flaps Up; when I'm heavy, the runway is much shorter than home [3000'], and/or DA is really high, I'll use Takeoff Flaps, but I won't hang them out all the way to 500' agl. I put a lengthy quote from my Owner's Manual back on Page 1 of this thread, but flaps come up when I've cleared the trees and am confident that raising flaps won't put me back down into them--call it 200-250' agl or less, depending on the trees, my load, climb rate, etc.

I'm up, then the gear is up, then the flaps come up, and then I really go up.

[Shadrach]

My mains will continue to spin into the gear retraction if I don't tap the brakes.  For those of you who feel that tapping brakes is overkill, consider this. At 70MPH our mains are spinning at just under 1500RPM and generating nearly 500Gs of centrifugal force...and gear retraction moves the rotational axis 90deg.  Maybe it's not a big deal, but I try to remember to tap before I retract, because the forces involved seem significant to me.. 

[aviatoreb]

Quote: Shadrach

My mains will continue to spin into the gear retraction if I don't tap the brakes.  For those of you who feel that tapping brakes is overkill, consider this. At 70MPH our mains are spinning at just under 1500RPM and generating nearly 500Gs of centrifugal force...and gear retraction moves the rotational axis 90deg.  Maybe it's not a big deal, but I try to remember to tap before I retract, because the forces involved seem significant to me.. 

[1970m20e]

Clean up as quick as possible due to the extra drag of the gear being down.  I fly out of a 2500 fot paved strip so there's no useable runway once I am airborne.

[byrdflyr]

Remember when looking at the gear retraction tests with the plane on jacks, the engine is not running, so with just battery power, the motor is going to turn more slowly.  At 2700 RPM climbing out, your alt or gen is providing more amps to the electrics, and the gear retraction will (should be) faster.  Seriously, in my "C" model, it seems to take about 2 seconds max.

Gear down seems even faster, so if I pull the gear up, and drop it down, that's about a 4 second cycle, with the engine turning at T/O power.

[jetdriven]

when you advance the throttle on takeoff, it belongs to the insurance company.   Dont worry about what youj can't control.  How fast it retracts or extends to me is no factor, unless its a Cardinal RG (13 seconds).  If the terrain is smooth, land gear down.  Same is it is very rough. 

[galt1074]

I'm intrigued by this discussion. I don't have a Mooney, never even flown one, just shopping. I barely have 10 hours in an Arrow II with retractable gear and I was amazed that the CFI that checked me out insisted that I not retract the landing gear until there was no useful runway left. This raised a couple questions in my mind and those same misgivings (I think) have been re-stated here.

I'm a military instructor pilot on MC-130Ps. We have four engines and over 16,000 horsepower so some of this may be off-base. The Air Force teaches, "2 positves, gear up". When I have an indication of increasing altitude and positive VVI I bring the gear up to make my charted climb performance. Unlike GA, there is a very specific speed schedule that we always fly. It doesn't matter what phase of flight I am in I have a to-the-knot speed schedule that I need to be on. If I do not retract my gear within three seconds of lift-off, feather the dead engine within 6 seconds of it dying, and retract my flaps on speed to meet charted obstacle clearance speed, I am not guaranteed to clear my obstacle. Now obviously this is different for me because I have four engines and you guys have one...but I don't see how you can plan for what you are going to do in every eventuallity of power failure. You can however plan to clear the obstacle at the end of the runway by retracting the landing gear in accordance with your POH.

Now, I don't know how in the world you even decide when you still have usable runway when you don't have any charted speeds or distances in the first place. (That POH line about rotate at 65 to 75 knots is NOT a charted speed...that's a WAG. I'm talking about, drag index, weight, wind, density altitude, RSC, RCR all goes into a chart and you come out with a rotation speed and a distance from brake release to clear a 50 foot obstacle.) I have a speed and a distance charted for nearly every scenario I can imagine so I am very sure when I have runway in front of me that it is or is not enough to stay on the ground but I would never put a fast airplane back on the ground with the end coming up quickly unless there were at least double what I had used to takeoff. You have to consider that you have to descend and land and then you can get on the brakes. You guys that have flown these airplanes a while might be able to WAG what that looks like but I'm pretty sure it would be a WAG at best.

Next, an off-airport landing for me is always gear down. But I have extremely tough gear and I plan to use it as a shock absorber since I essentially have no way of going end over end. I would assume in these airplanes that there is a fair likelyhood of going tail over nose so in that case if I were ever to land on something that wasn't paved off airport I would be inclined to land with the gear up. Your gear can't abosorb that much and the nose gear must give you some danger of flipping...and then you are pretty much dead along with your passengers.

Please, I'm not an expert in these airplanes so tell me how I'm wrong and tell me how I'm right. I'm trying to get back into GA but the mindset is very different from what I am used to and I need to learn.

 

Greg

[aviatoreb]

Quote: galt1074

...I'm a military instructor pilot on MC-130Ps. ...

...that's a WAG. 

Please, I'm not an expert in these airplanes so tell me how I'm wrong and tell me how I'm right. I'm trying to get back into GA but the mindset is very different from what I am used to and I need to learn.

Greg

[airfoill]

Quote: galt1074

Now obviously this is different for me because I have four engines and you guys have one...but I don't see how you can plan for what you are going to do in every eventuallity of power failure.

Now, I don't know how in the world you even decide when you still have usable runway when you don't have any charted speeds or distances in the first place. (That POH line about rotate at 65 to 75 knots is NOT a charted speed...that's a WAG. I'm talking about, drag index, weight, wind, density altitude, RSC, RCR all goes into a chart and you come out with a rotation speed and a distance from brake release to clear a 50 foot obstacle.)

[scottfromiowa]

Gear up after establishing positive climb.  If I lose power I have more altitude (better climb rate with gear up) and if able can put plane back on runway.  If I am landing off field I'm going gear up.  I am focused on flying the airplane and NOT stalling.  Flaps more important to me (slower) than getting gear down.  For those who wish to keep gear down until no run way fine, knock yourselves out, but I have read nothing that changes my mind here and in fact have read more to reinforce getting the gear up as I now currently do...after establishing positive climb.

[Shadrach]

 

RSC = Runway surface condition

RCR = Runway condition report

Drag index = is just what it sounds like, but on military aircraft must be calculated for every flight because of changes in loading and external stores...

Oh and WAG = Wild Ass Guess

Gualt is merely illustrating that military pilots calculate every aspect of a flight and fly the numbers based on those calculations.  I mentioned in another thread that took off from a 1800' undulating, turf strip last sunday. I ball parked the numbers and new I'd make it.  A military pilot will calculate the point of lift off, climb profile, obsticle clearence etc...etc.. The Majors do a great deal of this as well, which is why if Ground ammends their departure to a longer runway in the same direction, they still have to reprogram and get exact numbers.

Mooneys not so much!!! I think most of us look at the POH and build in or own cusions. To a military guy, this looks like a WAG.

Gualt, One thing that is hugely diffent for small birds, is the amount of feedback you get from the plane it self. With experience, you could fly a mooney all day long sans ASI, VSI, MP gauge, Tach etc... I doubt a C130 pilot would want to fly without their equivelents. You may find GA flying to be very liberating... 

 

[Hank]

C'mon, guys--a "WAG" is somewhat less accurate than an "Engineering Approximation." My POH says to rotate at 65-75 MPH, drop the nose a bit and accelerate into a climb. The charts in the back show Best Rate of Climb at Max Gross, Gear Up, Flaps 15, No Wind. [i.e., 100 MPH - 1 MPH per 1000' msl up to 10,000].

Greg, on the other hand, has to calculate his Rotate Speed based on his actual takeoff weight, runway available and other factors. I don't have the information to calculate either Rotation Speed, Rotation Distance or Distance to 50' for any takeoff conditions other than the one particular setup shown in the book. No, wait, I can interpolate between two weights and three sets of Density Altitude for Ground Roll and 50'. Do I do that on every takeoff? No. Since my home field is 3000' long with trees at both ends, I only worry about it if I'm going somewhere shorter.

Also, my home field has neither "gates" nor "hundreds of yards of grass beyond the paved runway." See the photo below. Once I know I'm in the air and climbing, the gear goes away and I hope to not have to choose between the trees and the river; other places have other choices, some actually have options.

Military pilots spend a lot of time in flight planning. I cannot calculate [due to lack of available information] the takeoff run, rotation speed, climb air speed and climb rate for every single departure. I know about how far it should take me to get in the air, I have a general set of guidance on air speed and climb rate that works for me, and another set that I use to baby the plane on hot, humid departures. There is nothing "exact" about anything, except when following the needles down on an approach in IMC. Even there, the POH gives precious little guidance--I get to choose my airspeed and time myself along the ILS based on what is on the approach plate, based in feet per nm and judged on my VSI in feet per minute and a little conversion table.

We have it easy! I took a retired B52 pilot to ride, and my thorough, complete and "by the book" pre-flight inspection took 5 minutes; he used to spend 1½ hours or longer, not counting time at the desk planning and calculating. I rotate at 70 MPH [75 if heavy and/or really hot], and make initial climb at 100 MPH after clearing the trees, 105-110 when really hot [watch the temps and speed up when needed]. This is for solo flight, half tanks in January when the temps are single-digits F, and for three people flightseeing with full tanks in the summer--Mr. C130 has different speeds, distances and rates of climb for different loads, different fuel amounts and different airports. That's the point he is trying to make.

GA flying is easy on purpose, it keeps it accessible. The book gives best performance, plan to be a little under it depending on your skill and comfort levels, loading and variable weather. We can't even agree to raise the gear for good climb rates. My wheels are tucked away before I reach tree-top level, whether leaving the nearby 2000' grass strip or the 10,900' Class C that I visit occasionally. When to raise gear will vary by aircraft type, though, as the wounded-duck Cessna gear create tremendous additional drag while cycling oh-so-very-slowly, but my electric ones tuck away in 2-3 seconds.

[Shadrach]

I agree with the positive rate folks.  If I clean it up, I'm at return to airport altitude in under a minute. Gear postion for off airport would depend on surface and situation.

I am sure many of you have seen this video, but for those who've not...

http://flash.aopa.org/asf/pilotstories/impossibleturn/

I think this video bolsters the position that getting up and out quickly is optimal. regardless of how you feel about what to do in a power loss on take off, this real world situation shows what is possible and I think showcases the efficiency of the airframes we fly. I'm not sure he'd have pulled it off in any other make.  

[fantom]

Quote: Hank

Greg, on the other hand, has to calculate his Rotate Speed based on his actual takeoff weight, runway available and other factors.

Greg also has a well trained co-pilot, and a navigator with little else to do, assisting him.

In general, military flying is not as much fun as Mooney flying, but hard IFR Mooney time can be just as challenging.

[Shadrach]

Quote: fantom