Snow Flying: Skis, Floats, & Flying Boats! - RC Groups
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Oct 26, 2010, 11:26 AM
High Altitude Flyer
viking60's Avatar

Snow Flying: Skis, Floats, & Flying Boats!

What works for you for flying from snow?

I've had skis & floats under a wide variety of aircraft over the years. Some should be flown from a smooth snow surface, while some will handle rough wind-carved snow surfaces well. Some setups will fly well from deep soft snow, while others work best from a firm snow surface.

Here are photos of & links to more info about a few of my favorite foamie snow fliers to start off this discussion- feel free to join in! Each of these aircraft designs below has it's own web page where extensive build details & photos can be found if you are interested.

The "FLIRT20" is my most recent snow flying design:

The Snowball T-tail, a variant of Lee's fine EPP Snowball, is another of my favorite snow flying aircraft. It's also a great water flier!

The VOYAGER is a sport aerobatic design with a KFm3 wing with EPP floats mounted directly into the wing spar structure- simple & ruggedly effective:

Woodstok is a slightly larger variant on Gene Bond's venerable Blu-Beagle; it flies with three different wings on a novel 'reverse trike gear' float setup that works very well from foam floats:

The lightweight 16" EPP Nutball "FLIRT" variant was originally set up to fly from snow on an EPP foam mono-ski- (it was later converted to a dual ski / wheel gear setup.):

OK, I've shown you some of mine... now you show me yours!!

Last edited by viking60; Oct 08, 2011 at 10:38 AM.
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Oct 26, 2010, 11:37 AM
springer's Avatar
Man, is it time for that again???? cloudy and 60's right now, but before long.....
I just posted a pic in another thread that happened to have my foam skis on her. At the risk of over posting a single pic, here's one of my favorite winter flyers, based on gpw's parkflyer pete planform.
Oct 26, 2010, 11:42 AM
High Altitude Flyer
viking60's Avatar
Originally Posted by springer
Man, is it time for that again???? cloudy and 60's right now, but before long.....
I just posted a pic in another thread that happened to have my foam skis on her. At the risk of over posting a single pic, here's one of my favorite winter flyers, based on gpw's parkflyer pete planform.

I'm looking out the window seeing more fine snowflakes settling, and I have to say that yes, it's time to get ready!

Nice Parkflyer Pete! If you have more photos of how you did your ski setup, please add them or link to where the info can be found so folks can easily find all of the good info.

Just 'cause it's soon going to be winter in a major part of the northern hemisphere, it doesn't mean we can't get in some fun flying!!


Last edited by viking60; Oct 26, 2010 at 12:20 PM.
Oct 26, 2010, 12:15 PM
High Altitude Flyer
viking60's Avatar

Mounting Skis on Wire Landing Gear

Here's a look at some very light weight skis mounted on my "Lite Stik SL" (No, this one's not a foamie... but it gets out to play in the snow too when it has the proper 'footwear'!)

These skis are made from 1/32" birch ply, with a poplar Lite Ply center spine. They also have a small tracking spine / rib down the center of the bottom of each ski to keep them tracking well on takeoff runs.

These skis use a 'torque rod' mounting system to keep the skis aligned while they are mounted. (It's a real bummer when your ski rotates on the axle while in the air, forming an instant AIR BRAKE! So you need to mount your skis so that does not happen!

I've seen a wide variety of cables, springs, and rubber bands rigged to try to keep skis in the proper orientation over the years, but all of those rigging approaches can have a tendency to fail eventually. Check & replace any suspect springs, rubber bands, shock cords, etc. regularly. Each of these materials can and will work, and for light weight aircraft there's not as much load on the rigging.

For long-term reliability (especially on larger heavier aircraft) the torque rod system has been the best approach I've used. I'm certainly not the only one that uses this type of rigging; I'm just an advocate of this approach. The simple key piece of hardware is the torque rod. Start with a wheel collar and a piece of music wire that's sized to handle the job on your size / weight of aircraft. Drill a hole in the wheel collar to closely fit your music wire. After making a nice square 90 degree bend in the other end of the torque wire, insert the other straight end wire into this hole in the wheel collar so that it extends close to but not into the axle hole, and secure it in place. (I like to use 2% silver solder for this job, but a bit of thin CyA glue may also work, as there's no 'pull' stress on this end of the torque wire.)

The wheel collar with it's torque wire is slid onto the wire axle, and a hole is drilled through the ski's center top mounting spine so that the torque wire end can extend through this new hole. When the wheel collar is locked down in position on the axle, the ski will be held in place.

Obviously if you are making skis out of foam, you will need to add a top center mounting spine where you will then have hard points for the axle and the torque wire hole locations.

More details of this type of ski and mounting technique are on my web site on the Winter Flying Page; some of that deals with aircraft up to over 17 pounds flying on larger skis which use the torque rod mount method:

Last edited by viking60; Oct 27, 2010 at 10:22 AM.
Oct 26, 2010, 12:26 PM
AMA 353531
rdeis's Avatar
I fit floats and lights to my Slow Stick and have never considered returning to wheels:

Rough dirt, grass, water, snow, pavement- it handles them all with ease.
Oct 26, 2010, 01:23 PM
High Altitude Flyer
viking60's Avatar
Here are some more photos of snow fliers from my collection, just to help get you into the mood for winter flying! (I realize it's a bit early for many of you- you may not have flyable snow where you are for another few weeks. )

For the larger / heavier aircraft, the forward tips of 1/8" birch ply ski blanks were soaked in boiling water for up to 8 minutes to make the plywood bendable, then clamped in place while the plywood dried & set in shape.

The plastic skis on the E-powered 3/4 scale Wild Hare were made from some 1/32" thick plastic bought from SIG Mfg. (This material showed some tendency to form cracks on landings in colder weather snow flying (~10 degrees F & lower?), but I still have a set or two in a drawer in the hangar.)

FFF skis have been successfully flown on many light weight foamie designs. There has been a variety of creative designing & rigging done.

Last edited by viking60; Oct 27, 2010 at 10:26 AM.
Oct 26, 2010, 01:50 PM
springer's Avatar
Snow already today? Keep it up there at 10k feet! I did dig back in the archives to find where I posted about my foam versions, Dec 2008! here's the post:

They aren't as durable as the ply skis, but work surprisingly well on the lightweight under a pound foamies which is pretty much all I build. I actually tried the torquerod version first for my 42" BluBaby, but it's only about 14oz, and I made the rod too stiff. Didn't get any springy action at all! I'd guess I either need a thinner piano wire for the torque rod, or just use on heavier planes. Still have the collar/rods in the "wheels" box.
Oct 26, 2010, 02:07 PM
High Altitude Flyer
viking60's Avatar

I vary the diameter of the torque rod based upon the weight of the aircraft; on a typical tail-dragger setup, there's usually enough spring in the wire so that, at rest, the tail end / tail skid is almost floating just above a hard surface. At this ski position, the bottom of the skis are set angled with their noses up about 10 to 15 degrees (which helps them to keep from digging in to the snow on landing.)

The torque rods on the big skis on my 17# tail-dragger are 1/8" music wire! I'm probably using .032" or .040" torque rod wire on the really light aircraft. On longer torque rod wires, I increase the diameter over what I might be able to use on a shorter torque rod wire.

You're right- you could always make another lighter wire set of torque rods if / when you wanted to try it again, and save the ones you made before for a heavier aircraft.

It's time to finish a bit of a work contract, then I'm planning to mount skis under the FLIRT20 again- it's a hoot to fly in the snow- you can do such utterly irreverent things with it on the ground / snow, and it gets away with it, no problem.

I may go ahead an design a set of slightly wider skis for it which also extend out a bit farther in front of the wing's leading edge; much of the snow I fly up here is deeper & softer powder snow. (And those changes would also fly just a bit better from water, too.)

While I can take off & land easily on the tire-packed snow surface on the dirt road at the end of my driveway, and while the FLIRT20 will maneuver in a moderate amount of airspace when I want, it's fun to get out in a more open flying area and do touch-n-goes and play around on the surface of the un-tracked soft snow, too. If I get them done, I'll post photos & details.

(Light snow is still falling as I'm typing this; the light is a bit flat for flying, so a close-in flier with bright color for visibility seems just about right for this afternoon.)


Last edited by viking60; Oct 27, 2010 at 02:25 PM.
Oct 26, 2010, 06:54 PM
High Altitude Flyer
viking60's Avatar
Here's a look at a variant / close cousin of the FLIRT20 on a set of the 1/32" birch ply skis. This fun flier is 20" long, 21-1/2" wide, with a 14"wide wing center panel. The 4" wide wing tip panels are set at 18 degrees. The top front KFm2 variant doubler panel extends back only 2-3/8" from the leading edge at the center of the wing. The leading edge is shaped, & covered with a layer of clear covering film (doculam laminating film).

The skis are now 2-3/8" wide x 7-1/4" long- (I just extended the tail ends on a set of shorter length skis I had built a year or two ago.). They also have a layer of the clear covering film ironed on their bottoms to allow them to slide very easily over the snow. The wire landing gear is simply taped in place on the under side of the wing after a base layer of the clear covering film had been ironed in place across the forward third of the bottom of the wing.

The aircraft weighs in at 10 ounces with the skis mounted and with a 2S 800 battery installed, ready to fly. With a wing area of ~2.8 square feet, that comes out to a wing loading of 3.6 ounces per square foot. The 24 gram Blue Wonder motor is turning a GWS 7x6 SF prop.

3 HXT500 servos control the elevons and rudder. The rudder is extended, hinged just beyond the trailing edge of the elevons, and now also extends ~1.5" below the wing to help balance out the response to rudder deflection for flatter turns. There are three tail skids under the trailing edge of the wing, one on center, and one on either outboard end of the elevons; these keep the rudder and elevons protected from rough ground & ice, from 'road rash' damage.

At this light of a wing loading, this fun flier will handle some wind- especially when flown with a higher pich prop for more speed capability. It's fun to fly with a larger diameter lower pitch prop, but when doing that, it gets carried away a bit in heavier winds. It's a good flier for a modest sized flying area; the elevons give it a good roll rate, and it also responds well to the rudder, which makes playing around on the ground a lot of fun, too!

The second photo gives a closer look at the torque rod installed in the wheel collar. I like to replace the grub screws in the wheel collars with larger socket head screws that I can really tighten in place on the axle.

Last edited by viking60; Oct 27, 2010 at 02:28 PM.
Oct 27, 2010, 11:06 AM
High Altitude Flyer
viking60's Avatar

Cold batteries

This morning there's about 3" of snow covering the ground, with the temperature at 13 degrees.... Brrrr! But this snow will be gone again within another 3 days, so I guess I'll get out & play in it while it's here!

The cold battery issue is always one that haunts winter fliers; GPW commented in the past that he's noticed that batteries loose performance (lose the ability to hold full voltage and deliver their normal current) when the temperature drops below 40 degrees. I certainly agree.

Keeping your batteries warm before you fly, and while you are flying helps maintain good flight performance. Yesterday afternoon while rigging these skis & before going out in the cold to fly, I made the battery enclosure that's shown in the photos below. (Before that, the battery was just velcro-mounted, hanging out in the wind.)

OK, let's see YOUR snow fliers!!

Oct 27, 2010, 12:12 PM
Registered User
jimsp's Avatar
This is my Nutball on snow using a single float.
lots of fun!
Nutball on Snow (1 min 11 sec)
Nov 04, 2010, 09:54 AM
High Altitude Flyer
viking60's Avatar

Looks like your mono / tri-float setup is working for you! There are certainly a lot of ways to rig for flying from snow.

We're snow free for now, but next week might bring us some.

Nov 11, 2010, 10:23 AM
High Altitude Flyer
viking60's Avatar

Keeping batteries warm

I woke up to about 3" of fresh dry snow this morning, no wind, and a temperature of about 15 degrees. Light was very flat earlier, but the storm is moving on east, and the light is definitely improving . I'll have some time to get out and make some tracks later today. But it's going to be a day where keeping the batteries warm before & while flying is a must!

A few years ago I found this 12 volt powered electric cooler / warmer at a TARGET store in the Christmas gift section; it was priced at around $25. It draws up to around 4 amps at 12 volts, as I remember it, and when switched to warming mode of operation on a cold winter day, will keep the interior & contents up to from 100 to 120 degrees F.

Starting a cold winter flight with a warm battery makes a lot of difference as far as the voltage levels (and the current delivery rates) which a battery can maintain. And keeping the battery from chilling down during a cold weather flight is also valuable. The 3rd & 4th photos below show one easy way of taping on a temporary battery 'overcoat' for batteries which are velcro-mounted out in the breeze.

On many of my aircraft, I've designed an enclosed battery carrying compartment where the battery is not as easily chilled by cold air.

Winter offers some great flying opportunities, so get out there and FLY!!! - But remember to keep your batteries warm!

Nov 13, 2010, 10:09 AM
Registered User
kepa's Avatar

Originally Posted by viking60
What what works for you for winter flying from snow?
Hand launching! And a flying boat or two.

I see you have quite a bit more batteries than I do. I just keep them in my pockets, and of course keep nothing else than a battery or two in any pocket. No sharp and/or metallic objects!

Snow can be a challenging element (but so can anything else). Packed snow isn't too bad, I just put my flying boat down on it and go. Softer snow has its risks. If I have to nudge the aircraft to get it to taxi and/or start the take-off run, I know I must not let it stop after landing if I wish to taxi back and avoid wading in the sometimes deep snow.

Powdery snow is very light but when packed tight, not so much. So in addition to keeping the battery warm(er), plugging all holes helps in keeping the CoG at its proper spot as well.

And if you do put the model into the snow nose first, make sure to scrape and blow away all snow and slush around and inside the motor and run it for a while as well. If you don't, don't (try to) run it until after some time in a warm place...


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