Short field rolling start?

Posted by Intelligent_Log515@reddit | flying | View on Reddit | 17 comments

So a Mooney pilot recently posted this video of flying an Acclaim into Oceano L52: https://www.youtube.com/watch?v=KLQKWtDSgVE Another user asked about her decision to use a “rolling takeoff” for the relatively short runway there (and her “rolling runup,” which she ignored), noting that the POH (can't find one for the non-Ultra Acclaim - which I think only added the second door - but here's the M20TN (p. 88); here's the Acclaim Ultra (p. 96); same short field takeoff procedure) listed the normal static push to full power short field departure procedure:

Wing Flaps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TAKEOFF POSITION

Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APPLY

Throttle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FULL (2500 RPM)

Mixture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FULL RICH

LOW Boost Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ON

Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RELEASE

Lift Off/Climb Speed . . . . . . . . . . . . . . . . . . . . . . As specified in SECTION V (Takeoff Distance)

Landing Gear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RETRACT IN CLIMB after clearing obstacles

Wing Flaps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . UP

She came back with this:

Often in real world settings, experienced pilots (especially bush pilots in really short strips in places like AK with one way in one way out landings like Kantishna 5Z5 ) will regularly be found doing rolling starts using turning momentum, and (for tricycle gear airplanes) left hand turning forces, to actually accelerate the take off. If done correctly, this can really shorten published T/O distances given by the POH/AFM for many different airplanes. I recommend if you have never done it, and since it is not sanctioned by any authority like the FAA, that you do try it with a qualified pilot who has the experience. You will feel the difference. Interestingly enough, the pilot of a Mooney Ovation happen to be taking off right before us and ended up doing the same maneuver

Anyone know what she's talking about? Is this a thing? I'm intrigued, but also not really likely to jump into using a technique “not sanctioned by any authority like the FAA.”

[-]

rFlyingTower@reddit

This is a copy of the original post body for posterity:

Wing Flaps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TAKEOFF POSITION

Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APPLY

Throttle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FULL (2500 RPM)

Mixture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FULL RICH

LOW Boost Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ON

Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RELEASE

Lift Off/Climb Speed . . . . . . . . . . . . . . . . . . . . . . As specified in SECTION V (Takeoff Distance)

Landing Gear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RETRACT IN CLIMB after clearing obstacles

Wing Flaps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . UP

She came back with this:

Often in real world settings, experienced pilots (especially bush pilots in really short strips in places like AK with one way in one way out landings like Kantishna 5Z5 ) will regularly be found doing rolling starts using turning momentum, and (for tricycle gear airplanes) left hand turning forces, to actually accelerate the take off. If done correctly, this can really shorten published T/O distances given by the POH/AFM for many different airplanes. I recommend if you have never done it, and since it is not sanctioned by any authority like the FAA, that you do try it with a qualified pilot who has the experience. You will feel the difference. Interestingly enough, the pilot of a Mooney Ovation happen to be taking off right before us and ended up doing the same maneuver

Anyone know what she's talking about? Is this a thing? I'm intrigued, but also not really likely to jump into using a technique “not sanctioned by any authority like the FAA.”

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RexFiller@reddit

I find even on hard runways, the rolling start gives a shorter takeoff. Basically from the hold short line go to 1700 rpm, verify everything is making good power then go onto the runway and turn onto centerline. By the time you turn onto the runway you're already doing 20+ knots and can get up sooner.

That being said, I would never do this in a real short field. Its much safer to bring up full power and make sure your engines are making full power with instruments in the green. I figure if I truly need to take off in 200 feet less than a POH short field takeoff then I probably shouldn't be there in the first place. There is a lot that could go wrong while on a rolling start, especially trying to maintain centerline and short fields are often not the widest.

aftcg@reddit

Say goodbye to your props then? Short usually means shytty runway. Sometimes as an airplane owner with 6 very expensive blades, and even more expensiver big bore connies I'll accept the risk that my engines will do their job correctly - as they have reliably for the last 500+ takeoffs and 5 years of service.

Also, assuming you're flying a Baron, do you enter the runway with 1700 rpm at 20 kts? I'd worry about the stress on the gear, and especially the spar web carry though.

Ive never done it on a short field. What I described is basically a normal takeoff when ATC clears you with no delay. By the time im established on centerline pushing power forward, its about 20+ knots. Shouldn't be any excessive wear to the gear. Ive just personally noticed thay my no-delay rolling take offs end up with me lifting off at an earlier point compared to the short field technique

poisonandtheremedy@reddit

She's correct. The POH technique is written to "Everyone Everywhere" to be able to replicate, with lawyer oversight.

Telling people in official documents to 'power thru the turn onto the runway and blast outta there in a short field scenario' is just ripe of lawsuits and wadded up planes from people that lose control.

makgross@reddit

WTF?

Oceano isn’t a particularly short field. So, it doesn’t matter. Especially since there is nearly always wind along 29.

Didn't you know? Anything under 4,500' is a short field!

I know pilots that won't fly to Catalina because it is 'too short' at 3,500'. They landed DC-3s there.

Plus_Goose3824@reddit

So I've done a J takeoff in a taildragger several times before. I did a backtaxi on the very edge of the runway and did my run up facing 180 from my intended takeoff. Then, you apply power in a controlled manner through the 180 turn to get centered on the runway and go. On a soft field, you don't have to worry about getting bogged down by grass or mud because you are already rolling. I tried looking up videos of this, but it must not be common because I didn't find any readily. The specific runway makes this advantageous, and it's not something I do regularly.

NO_SURF_IN_RI@reddit

Physics. You can store a heck of a lot more energy in the airplane by keeping it moving than you can in the propeller by running it up to its max static. Bonus points if whatever you are taking off of is soft and you don't want to get stuck.

That said... if you watch the clip she waits a lifetime to pull the gear up. If she needed the extra performance of the rolling start she should have had that gear tucked as soon as that Mooney was in ground effect.

If you want to watch someone work a Mooney (granted its a m20c with a johnson bar) in and out short go check out piperpainter. Here is a clip of them pulling the gear up immediately: https://www.youtube.com/shorts/M2jxlupGO_E

SSMDive@reddit

I don't know the Mooney well enough to talk about it, but with the 12V Bonanza's on a short field you do not want to raise the gear as soon as possible. The first step of the gear cycle is opening these gigantic wheel well covers creating a ton of drag that lasts the entire gear retraction cycle. You get better climb performance if you just leave them down till the obstacle is cleared. I have been told the same advice on the MU2.

People very often use a rolling start for a short field. If you can get 5-10 knots already in the bank before you start your TO roll that is free momentum. If I am in a short field and in a plane that allows it (not like a Bonanza that does not allow turning TO's) and it will not eat up too much runway that is what I do.

In addition many short fields are also soft. You don't want to get stuck when you lock the brakes and run up the throttles digging a neat little trench. The full throttle run up on a soft field or worse gravel will also ding your prop.

Starting your TO run XW and rolling into the wind is the technique for seaplanes in small ponds. There are other reasons for this (no brakes), but if you can get some speed before you line up and launch that is "free".

The only risk is if the engine does not make full power, but you can check that pretty quickly once you go full throttle.

Headoutdaplane@reddit

I have flown in Alaska on and off airport for the last 17 years.

We never stop at the end of our takeoff area to bring the engine up to full power and then release the brakes. Why would you give up the momentum that you have? Why would you trash your prop?

I do not know why the FAA teaches that technique that nobody in the field actually uses. My suspicion is that, similar to competition they have to get exact distance measurements.

It is the same with landing techniques. Spot landing is much more important than what you do after you land (eg pull up your electric flaps). A great example of this is the competitors at Valdez, if they do not land their spot they are not in the running at all.

mtconnol@reddit

My understanding is that the brake hold doesn’t reduce takeoff distance; it just allows for verification of engine instruments before you might be past an abort point on the short field.

Low_Sky_49@reddit

The static start takeoff procedure is repeatable by anyone. Is a good basis for takeoff performance charts because any pilot can do it and get the same results.

The rolling start off the taxiway can yield better performance, or worse. It depends on pilot skill, which is an impossible thing to quantify in a performance chart or table.

hmasing@reddit

Mooney pilot here (albeit a 4-banger vintage F). I regularly use a "rolling start" at my home airport from the hold short line. Yes, we have 3500', but I find I am usually in the air about 200' sooner if I use those extra 10-ish knots of rolling speed instead of a static start.

shrug YMMV, but I use that technique from time to time. Don't really even think about it until I see a post like this.

Apprehensive_Cost937@reddit

Rolling takeoff on short field are sometimes a better option, because short fields often also tend to be on the soft side, especially in the winter months. On a hard surface, you're probably better off doing the "static" takeoff, and verifying the engine is producing as much power as it should, before releasing the brakes.

Also, what's with not keeping the hand on throttle after power is set?

Anthem00@reddit

I have never done it as I’m never at those marginal things - but it is a thing with bush pilots and others. Even on paved runways - some will start accelerating through the hold short line and as they are turning. Is it “better/faster” - dunno. But I imagine you can easily get to 10-15 mph as you are turning to line up down the runway.