Float plane take off distances?

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downtomda
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Float plane take off distances?

#1 Post by downtomda » Wed Dec 29, 2010 10:05 pm

Just curious to typical take off distances for small float planes like C172, C180, etc.? What size of lake do you need to get in and out comfortably? Any other info would helpful.

Thanks.
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Re: Float plane take off distances?

#2 Post by North Shore » Wed Dec 29, 2010 10:20 pm

Well, start off with the float supplement for your bird, and work the graphs to get a 'book length'. Then, I'd add ~10% to compensate for an old engine/prop/airframe, and then round up to the nearest 500' (ie, 1200' = 1500') Once that's done, then I'd fly by your selected lake at 120kts, and count - 1 second is roughly 200' at that speed. Assuming your lake is greater than the 1500' example given above, then you'd be good to go. Once you've done that a few times, then you'll get a feel for how well your plane performs, and you can start shortening accordingly. Don't forget, though, that your plane will stop shorter than it will go.

ETA: Well, it appear as if I have misunderstood your question! I assumed (Yes!) that you had a plane and were asking advice. As for actual numbers, I have no idea... when I flew a 180, I just used the same lakes as I used in the 185, and they just 'looked right.' That being said, home base was almost a mile of water, so it wasn't that critical..
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Re: Float plane take off distances?

#3 Post by Slats » Wed Dec 29, 2010 11:43 pm

downtomda wrote:Just curious to typical take off distances for small float planes like C172, C180, etc.? What size of lake do you need to get in and out comfortably?
Depends on all the usual factors: wind, temperature, altitude, take-off weight, obstacles, etc. Also depends on technique and exactly what you consider "comfortable." I've had to do my fair share of small "lake" work in a number of locations. Google Earth puts the smallest one at 1900' length, and if memory serves probably 600-700' altitude and roughly 30' trees. Was in and out in both a Beaver and 206 multiple times...206 was always empty on departure and Beaver was loaded. A slightly longer but more challenging one is 2200' in length, but around 3500' altitude and 50' or better trees. In and out in Beaver and 185 many times, both always empty on departure.
The Beaver makes all short spots more "comfortable."
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Re: Float plane take off distances?

#4 Post by Blakey » Thu Dec 30, 2010 3:05 am

downtomda wrote:Just curious to typical take off distances for small float planes like C172, C180, etc.? What size of lake do you need to get in and out comfortably? Any other info would helpful.

Thanks.
Short answer - Your lake is too small!

If you have to ask, then it is just a matter of time until there is a day, or a load, that will render your lake too small.
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Re: Float plane take off distances?

#5 Post by downtomda » Thu Dec 30, 2010 8:54 am

Thanks for the info, although, I don't have a lake and don't have an airplane. I am simply asking what size of lake you can typically get in and out of. I don't have access to float supplements or any publications. I'm sure some have you do, so if you have any numbers for an example that would be appreciated.

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Re: Float plane take off distances?

#6 Post by GreenStar » Thu Dec 30, 2010 9:12 am

Blakey, do you have inside information as to why downtomda had asked the question, that qualifies you to make such a rude remark? It may be a legitimate question from someone that is just trying to get a feel for what is acceptable, as he is not familiar with float flying. Welcome to Avcanada downtamda, ignore alcohol induced statements, feel free to ask questions, most will be happy to answer. Knowing what altitude above sea level the lake is, how high the trees and terrain around the lake is, would be helpful information in coming up with an answer to your question.
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Re: Float plane take off distances?

#7 Post by nofate » Thu Dec 30, 2010 9:37 am

Before going into a new lake I usually check it out with Google Earth. You can measure distances for takeoff runs using the ruler tool. You can also see shallow areas that might best be avoided.
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Re: Float plane take off distances?

#8 Post by Slats » Thu Dec 30, 2010 9:52 am

nofate wrote:You can also see shallow areas that might best be avoided.
I strongly disagree with that. In my experience, Google Earth does NOT have the resolution required, even in the clearest of lakes, to reveal potential hazard areas in the water. It can be helpful to scope out a new lake and get a feel for it's shape and potential approach/departure areas and the ruler function can be useful, however, it should NEVER replace proper inspection of a proposed landing area.
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Re: Float plane take off distances?

#9 Post by nofate » Thu Dec 30, 2010 11:27 am

Slats wrote:
nofate wrote:You can also see shallow areas that might best be avoided.
I strongly disagree with that. In my experience, Google Earth does NOT have the resolution required, even in the clearest of lakes, to reveal potential hazard areas in the water. It can be helpful to scope out a new lake and get a feel for it's shape and potential approach/departure areas and the ruler function can be useful, however, it should NEVER replace proper inspection of a proposed landing area.
I have seen obvious shallow areas of lakes on Google Earth. Depends on the wave action on the lake at the time of the photo I guess. I agree that a good inspection of the landing area is best.
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Re: Float plane take off distances?

#10 Post by NWONT » Thu Dec 30, 2010 1:26 pm

Actually, Blakely's answer wasn't that bad. Sonner or later you're going to land on a lake with a 10 or 15 knot wind, stay there for a few hours and find the water has gone glassy or the wind has changed and possibly you need to do a crosswind take-off. How big is the lake now?
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Re: Float plane take off distances?

#11 Post by Liquid Charlie » Thu Dec 30, 2010 5:17 pm

it's not science it's an art and all about experience and knowing your airplane -- too many variables and difference in technique and styles to believe performance data -- when it looks good -- taxi the same distance again and have that escape plan or cut off point ----
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Re: Float plane take off distances?

#12 Post by polar one » Thu Dec 30, 2010 5:33 pm

As arule most lakes are also surrounded by hills os not only the length needed for takeoff, but sufficeint distance to outclimb the rising terrain. Lots of planes got airborne only to hit the hill at the end or stall trying to turn away from it.

As someone mentioned, until you really know your plane, the taxi and retaxing is the best advise.

Once you start flying a floatplane you will quickly learn what you can and cant do . Be caustious to start. There usually are some older pilots around with good advice.
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Re: Float plane take off distances?

#13 Post by boozy » Thu Dec 30, 2010 7:20 pm

All the stuff above about too many variables to give good numbers and such...that's more or less true which is why I don't really know the numbers myself. But, I just did a little measurement to get a rough approximation for ya. The guy flying a Cessna 180 this summer out of Mattice Lake by Armstrong Ontario would take off in about 2000 to 3000. And he was a low timer to start with and handled it quite well as the summer went on.

2000 for a lighter load with say 10 kt on the nose

3000 for a jag with crosswinds.

The above is just rough from thinking about were he broke the water a lot. To be honest an empty cessna with a good headwind would probably be a good bit under 2000 and a loaded cessna on a hot day well...we've all seen them stop and taxi back to the dock to unload a few cases of beer.

Hope that helps a bit.
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Re: Float plane take off distances?

#14 Post by boozy » Thu Dec 30, 2010 7:23 pm

Also, the above numbers are with respect to breaking water...climbing...well that's another story!
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Re: Float plane take off distances?

#15 Post by zed » Fri Dec 31, 2010 3:29 am

Downtomda,

If you haven't caught on, flying floatplanes is very situationally dependent... Your load, the water conditions, the size and shape of the water area, modifications to and/or weight gain to the plane since it left the factory, your ability, the weather conditions, etc etc...

However, here's a copy of a 180 POH Floatplane Supplement. Since you aren't planning on actually flying, and just trying to understand, you can work out some generic accademic numbers from the chart on page 22. But I emphasize these are for the perfect conditions, perfect plane, as tested in 1978. Most floatplanes being flown now, are not likely to have actual performance matching its POH numbers.

And as Boozy mentioned, getting off the water is only the start, because in a lot of places where you have limited water, you may also have hills/mountains/tall trees/man made stuff, etc which must be climbed up and over. If you don't have a decent climb rate after your floats are out of the water, then it can still be a challenge to get up and over these obstacles safely. Enjoy.
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Re: Float plane take off distances?

#16 Post by Darkwing Duck » Fri Dec 31, 2010 5:31 am

nofate wrote:Before going into a new lake I usually check it out with Google Earth. You can measure distances for takeoff runs using the ruler tool. You can also see shallow areas that might best be avoided.
Just wondering what was done to determine the size of the lake prior to Google Earth? How would one determine if it was sufficient to handle all the current variables? What would happen if you have to divert to another lake due to wx, rough water or a big lake monster at the destination lake? I think this was kind of what Downtomda was trying to get at. Also makes me wonder how the folks now a days would navigate without a GPS? Gotta dial in those VOR thingys and watch for a needle swing?
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Re: Float plane take off distances?

#17 Post by boozy » Fri Dec 31, 2010 7:11 am

I used Google earth in the above post because I'm too lazy to pull a map out of my flight bag and measure. I would never use google earth in real practice. I think lake inspection is almost the most important part of a float pilots job. You can do it on the fly too or as you go with little preparation. When the weather is getting the best of me, I'll often end up inspecting some random lake at my "comfortable" minimums and landing there. Often it's a lake I've never landed on or on some other stretch of a familiar lake I've never been too. It can be the death of ya trying to fly an extra 2-5 miles to a lake your familiar with in the #*&$ weather. You have to know how to adjust your plans.
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Re: Float plane take off distances?

#18 Post by Slats » Fri Dec 31, 2010 9:26 am

Darkwing Duck wrote:Just wondering what was done to determine the size of the lake prior to Google Earth? How would one determine if it was sufficient to handle all the current variables? What would happen if you have to divert to another lake due to wx, rough water or a big lake monster at the destination lake? I think this was kind of what Downtomda was trying to get at. Also makes me wonder how the folks now a days would navigate without a GPS? Gotta dial in those VOR thingys and watch for a needle swing?
Settle down. :wink:
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Re: Float plane take off distances?

#19 Post by Cat Driver » Fri Dec 31, 2010 10:21 am

Also makes me wonder how the folks now a days would navigate without a GPS? Gotta dial in those VOR thingys and watch for a needle swing?
Map?
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Re: Float plane take off distances?

#20 Post by Northern Flyer » Fri Dec 31, 2010 12:01 pm

Slats wrote:
Darkwing Duck wrote:Just wondering what was done to determine the size of the lake prior to Google Earth? How would one determine if it was sufficient to handle all the current variables? What would happen if you have to divert to another lake due to wx, rough water or a big lake monster at the destination lake? I think this was kind of what Downtomda was trying to get at. Also makes me wonder how the folks now a days would navigate without a GPS? Gotta dial in those VOR thingys and watch for a needle swing?
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Re: Float plane take off distances?

#21 Post by Bushav8er » Fri Dec 31, 2010 3:40 pm

Cat Driver wrote:
Also makes me wonder how the folks now a days would navigate without a GPS? Gotta dial in those VOR thingys and watch for a needle swing?
Map?
Aside from a good 'look-see', when things were questionable I'd set up to 60 kts (70 mph) for a 100 feet per sec, shore to shore and measure the lake. Of course you have to allow for wind and climb but at least now you have a figure you can work with.

VOR...or ADF? In the bush? Map, compass and heading my man. There is usually no way to hit a target right on so I'd set up an error to either the left or right so that when I hit my distance, or time or river, I knew which way I had to turn.
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Re: Float plane take off distances?

#22 Post by ruddersup? » Sat Jan 01, 2011 3:58 pm

Maybe a little off topic but here goes:
In a first time small lake I usually set up an approach with a little power, 1/2 flap, and a reasonable (not steep) approach and carry it through the flair where touch down is predicable and then go around. If your go around is not white knuckles then it is apparent that this kind of landing can be conducted safely and it "should" be doable on takeoff. Now you perfectionists, shhhhhh.
An approach like this down low to water will show you what's in store for the takeoff too.
Now if it is glassy water then the challenge begins. If your experience is limited try this little trick. Let me know if anyone has done this.
On a glassy short narrow (hope) lake make an approach with 3/4 flap, in the opposite direction you wish to land, carry it fairly low to the surface (watching shorleline) and then go around. More times than not the aircraft will generate wind and a ripple, really. Now land in your usual direction. Should bottle this huh?
I hate small glassy round lakes, can't get close to shoreline to judge height. Anyone find them difficult too (controlled crash)?
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Re: Float plane take off distances?

#23 Post by Cat Driver » Sat Jan 01, 2011 5:14 pm

A glassy water approach and landing is nothing more than setting up an attitude that is best for the given airplane at touch down and using a power setting that gives between 100 and 200 feet per minute rate of descent.......once past the shore line you should not need any visual clues other than the horizon be it natural or instrument.

In the PBY the pilot flying fly's the airplane by reference to the instruments with a 4 degree nose up attitude at a power setting that gives an airspeed of 72 knots and a rate of descent of 150 to 200 feet per minute.

The pilot not flying looks outside for debris or any other issue such as running out of sufficient water ahead if a go around is necessary the pilot not flying calls for the go around.
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Re: Float plane take off distances?

#24 Post by ruddersup? » Sat Jan 01, 2011 5:23 pm

Chuck,
In a short glassy lake you cannot set up a slow decent, you'll run out of water. Can't use a glassy water approach, this is the problem. It is strictly visual, you and the shore line. IMHO
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Re: Float plane take off distances?

#25 Post by Cat Driver » Sat Jan 01, 2011 5:26 pm

How do you judge when to flare for the landing?
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