HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Nov 10, 2012, 02:28 PM
Registered User
how much's Avatar
United Kingdom, England, Wigan
Joined Jul 2011
776 Posts
Discussion
Q; whats the knack for not skipping stones with a Cub?

All

ok! my second outing today with my world models 72" Cub on home made floats..

have really got this model "dialled in" with regards the flying, turned a monster into a pussy cat by reducing the rudder throw on rates, raising the ailerons around 2mm at the tip and dialling in a pile of aileron differential (around 75% up - 25% down) not bothered with mixing aileron-rudder on the tx as its no big deal to mix it on the sticks

so here is a pretty poor video from today.. please play it without sound because there is loads of back chat and barking dogs etc..

oh! the question?


what is the "Knack" for nailing the landing and not skipping the damned thing accross the lake like a flat pebble?

i did several more after this one that were really good aproaches (wind was left to right today) and the end result was bouncy bouncy!

model all up ready to fly is just under 7pounds, when it was on wheels it was only 5.5 pounds and was a real floater... refusing to land and floating past the end of the runway

not new to flying... but still finding my way with the float flying


oops.. nearly forgot the video... excuse the wandering take-off... i had left the rudder rate switch on.. which effects the throw of the water rudder

Piper Cub on Floats 72" world models (2 min 49 sec)


i await the widom of the educated collective

David
how much is offline Find More Posts by how much
Reply With Quote
Sign up now
to remove ads between posts
Old Nov 10, 2012, 05:26 PM
Fuzzy Member
lupy's Avatar
Renton WA
Joined Oct 2001
825 Posts
1st impression; you are dropping too fast. notice that there is a little stall, or change in angle of attack about 5 ft above the water, the angle of decent then increases. When you hit the water at that angle the skip isn't supprising.
When you hit nose down, the part of the float in front of the cg hits first, the plane rotates nose up and skips.
Try touching down slower and keep the nose up. If the nose is up, then the step of the float hits first trying to pull the nose down which is what you want

Changing from 5.5 to 6.8 lb is a lot, but I have seen heavier planes land just fine. it should still be very flyable.
lupy is offline Find More Posts by lupy
Reply With Quote
Old Nov 10, 2012, 08:21 PM
Registered User
United States, SD
Joined Aug 2010
1,082 Posts
I think you just need to be more steady with your elevator and let it float more. You will get it with practice.
Kyler1 is offline Find More Posts by Kyler1
Reply With Quote
Old Nov 11, 2012, 03:19 AM
Registered User
how much's Avatar
United Kingdom, England, Wigan
Joined Jul 2011
776 Posts
yes thanks guys..
watching the video back i can see exactly how i touched down (dumped it) "nose down"

i can see i am going to have fun mastering the knack of keeping the nose up, not getting so slow it tip stalls, and trying to get it to break through the ground effect in the nose up "flaired" attitude that will have it landing in the lake next door

thats what i love about this hobby... allways new stuff to learn

David
how much is offline Find More Posts by how much
Reply With Quote
Old Nov 11, 2012, 05:27 PM
Registered User
Fla.
Joined Apr 2005
989 Posts
I agree with lupy that you are diving for your landing. You need a longer slower approach with more throttle management. I also agree about trying to set down right at the step . A bit more practice should do it. Remember " a good approach makes for a good landing " .
ENJOY !!! RED
redh is online now Find More Posts by redh
Reply With Quote
Old Nov 11, 2012, 07:00 PM
Fuzzy Member
lupy's Avatar
Renton WA
Joined Oct 2001
825 Posts
The "lake next door" effect usually means that you are moving too fast, this is often in response to a plane that tip stalls.
You have the right idea by twisting up the outer edge of the ailerons, does it still drop a tip in the stall? You could try a little more warp at the tips and see how it stalls then.

I just watched your landing again, it looks like you are still in control near the end of the first big skip, the wing does not look stalled, so if you land at that speed, you should be fine. Idealy, get to 1ft or less off the water, nose up, then just wait for it to slow down and stall onto the water. One of the great things about water landings is the really long landing strip. After you do this 50 times, you will have a much better idea how slow you can start your approach. This will greatly decrease your landing distance.

Remember, you can't use down elevator to fly it down to land, this increases your speed and guarantees a skip. Cut the throttle, keep your nose up, and the plane will come down on it's own. Add a little throttle if the speed drops to stall range too early. Also some planes respond better with a little more prop wash over the surfaces but it's usually not needed on early aproach.

Best of luck!
lupy is offline Find More Posts by lupy
Last edited by lupy; Nov 11, 2012 at 07:22 PM.
Reply With Quote
Old Nov 11, 2012, 08:18 PM
Seaplane Nerd
JimCasey's Avatar
Joined Jan 2005
842 Posts
Yep, you touched the water nose-down with plenty of airspeed. '

I find it useful to gauge altitude by the reflection in the water. Level off with the reflection a few inches from the plane , then let the plane settle.

Another thing that sometimes gives a surprisingly smooth landing is to land with the plane in a slight bank.

Practice by flying as low as possible, at a slow speed, but above stall. Control altitude with one-or-two click adjustments of the power lever. If you get in trouble, add power and get some safety altitude. I was doing this one day and made my greatest landing ever.

But you still must not dive into the water as you did in the video. It would have made for a bouncy landing also on wheels, if it did not break the prop or knock the LG off the plane.
JimCasey is offline Find More Posts by JimCasey
Reply With Quote
Old Nov 12, 2012, 01:19 AM
Registered User
how much's Avatar
United Kingdom, England, Wigan
Joined Jul 2011
776 Posts
all taken on board guys thanks for your input.

the video was only my second outing flying it off water, and it was the first flight after adjusting the ailerons and adding the diferential and i still wasn't relaxed on the sticks.
the handling of the model is transformed by the adjustments, with the tendancy to tip stall massivly reduced

here is a photo from yesterday's (my 3rd time) and it was a different story as i get more confident with it and find its and my limits with it.. was having a blast!

the perfect touch down......



just got to get more stick time and practise but its getting there

David
how much is offline Find More Posts by how much
Reply With Quote
Old Nov 12, 2012, 04:25 PM
60 years of RC flying
Daedalus66's Avatar
Canada, ON, Ottawa
Joined Feb 2006
16,966 Posts
Very nice picture. And it shows the attitude you need to get a smooth touchdown. It looks as though you are rapidly overcoming your problem.

As everyone says, you have to get slightly nose up and well slowed down for consistently bounce-free landings (it is possible to land faster than stall speed but it's difficult to do consistently, and even then you have to be sure that have the model in a level attitude when it touches, not nose down).

As for landing in the next lake, the answer is you have to learn to do slower and consistent approaches. You can't dive on approach and then try to get rid of speed by touching down too soon.

The other answer is to install flaps that go well down to create lots of drag.

By the way, none of this is specific to the Cub.
Daedalus66 is offline Find More Posts by Daedalus66
Reply With Quote
Old Nov 12, 2012, 06:54 PM
Art Schmitz
United States, TN, Crossville
Joined Jan 2012
392 Posts
Along with the excellent advice already received, try to touch down with the transom / rear hull (s) contacting the water ever so slightly first. This technique works well with single hull or floats. It doesn't always happen, but the overall attitude at touch down will be closer to ideal.
Observe the more pointed transoms on the WW II military float planes. They were designed to land in heavier seas than civilian type water flying. The lesson here is that floats with smaller width transoms are easier to touch down with as they tend to not skip due to less area touching the water first.
I used to scratch build G&S designed floats because of the narrower transoms...gave away my Goldbergs and GP's.
Attitude controls airspeed...landing slightly nose high with a little throttle, as it has been stressed, will solve the skipping. As Jim pointed out as in full scale practice, touching down on one float works well ..and looks SO cool !
Nice looking plane !
lindart is offline Find More Posts by lindart
Reply With Quote
Old Nov 12, 2012, 07:45 PM
Seaplane Nerd
JimCasey's Avatar
Joined Jan 2005
842 Posts
When you practice good float landings, you will notice your wheeled landings miraculously become much better.
JimCasey is offline Find More Posts by JimCasey
Reply With Quote
Old Nov 13, 2012, 09:24 PM
Fuzzy Member
lupy's Avatar
Renton WA
Joined Oct 2001
825 Posts
Much improved!, Nothing like a little practice

I have several thousand landings on water and I still ocasionally skip. My old lanier mariner (v bottom) I could consistantly touch down in exactly the same spot, time after time with nary a skip. My Neptune (flat bottom) skips more, and is not as easy to stick.
One of the marks of a good seaplane is how forgiving it is of skipping without then tip stalling or nosing over and filling itself with water.
lupy is offline Find More Posts by lupy
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion what is the best ESC for q multirotor ? jordanmeir Multirotor Talk 6 Oct 19, 2012 05:26 PM
Discussion what to make with broken parkzone micro j3 cub? FlyBoysRc Scratchbuilt Indoor and Micro Models 9 Jul 24, 2012 09:31 PM
Discussion What not to do with the FY31AP Shadrack FPV Talk 4 May 21, 2012 09:56 AM
Question Whats up with the 'Q' and 'S' on the Tx Sculptor Beginner Training Area (Heli-Electric) 9 Mar 30, 2012 04:41 PM
Discussion Skip socialism go straight to fascism, do not pass go, do not collect $200 Lightnin Life, The Universe, and Politics 34 Aug 12, 2009 10:04 AM