Backcountry Pilot • Lessons from learning to Ski Fly

Lessons from learning to Ski Fly

Two of the best inventions ever, skis and airplanes, together.
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Lessons from learning to Ski Fly

I thought it might be useful to others to share the lessons I'm getting from learning to ski fly, a new adventure for me.

A great resource is right here written by MTV, believe me I read it a couple of times and no doubt will re-read it:
https://backcountrypilot.org/knowledge-base/pilots/ski-flying
https://backcountrypilot.org/knowledge-base/pilots/ski-flying/164-intro-to-ski-flying-operations


Day 1.
Wow, the skis are on and I'm about to take my first flight. I am filled with apprehension. My hangar floor is crushed asphalt so to not risk damaging my new skis I nailed two pieces of plywood to the ground for the skis to sit on. In front of that I threw snow on the ground. I start the the engine, let her warm up, apply power and taxi out of the hangar to the right and into the snow. I use short bursts of power to blow the tail around so I can turn. I taxi to the intersection of my cross runway and make a few turns in both directions. The snow is dry powder and about 12" deep. I taxi back to in front of the hangar and swing the plane around to face down the runway. I shut down, get out and finish loading the plane.

I get back in the plane, ready to fly, begin applying power and the plane is stuck in place. Full throttle, swinging the rudder from side to side and the plane doesn't budge. I shut down and hop out. Lesson-I take out my new, really cool, light-weight avalanche shovel and realize it will take forever to move snow with this tiny thing. So I grab my regular snow shovel, dig the snow out from around the skis. Lesson-remembering something MTV has written I lightly kick the front and back of the skis until I see them move. It's a beautiful sunny day and now I'm ready to fly, off I go, a three-point takeoff cause I don't want to risk the ski tips catching in the snow. MTV noticed this watching the video and mentioned it's better to get the tail out of the snow and it's okay for the tips to be in the snow on takeoff, a "feel" the tips balancing act.
https://vimeo.com/243785527


Day 2.
Gray and overcast. The plane is sitting on the plywood, warmed up and ready to go. I apply power and she stays right where she is. I go to full power again swing the rudder from side to side, nothing, stuck, for a second day in a row. Lesson-even sitting on plywood the skis had enough snow on them from the day before that they froze to the plywood. And it doesn't take much freeze at all to keep a plane from moving. Lesson-I was monumentally stupid throwing full power at it while in the hangar. Of course lots of loose asphalt got blown backwards. I was lucky no damage was done to the prop or the tail. And, as I'm about to learn, had just one ski broke free I'd have taken out my plane and the hangar.

I shut down, hop out and gently kick the skis front and back. She's free. I climb back in, fire up and begin taxiing out of the hangar. As I do so she starts turning left. I'm full right rudder and instinctively I press the right brake. I feel the carbide tips of the Grizzly Ski Drag biting at the surface of the plywood but the plane continues left. Still partway in the hangar I again shutdown, climb out and straighten the plane. I get back in and with full right rudder I start taxiing again, and turning left. Convinced something must be wrong with the rudder I glance back at the tail. Nope, it's working fine. With full right rudder, and throwing bursts of power, it still only turns to the left. I surrender, left rudder, and turn a full 270 degrees to the left so I'm facing down runway. Lesson-On skis you can't necessarily steer the plane in the direction you want to go. So have an alternate plan.

Remembering what MTV had mentioned the day before about getting the tail up I did just that, but still with a tiny bit of apprehension- off I go. I know now that I can get the tail even higher if needed with no real worry of the skis digging in. Surely a learning process for me.

The gray overcast sky creates a flat light condition, unlike the day before I can not see where the surface of the snow is on the lakes. Keeping a peripheral eye on the trees along the shoreline I ease onto the snow's surface. Even high-speed taxiing across the snow I can't see the surface. It's a little easier to see the surface after I've laid tracks down, but only in the immediate area of the tracks. I'm carrying some black trash bags with small rocks in them to throw out under these kinds of conditions in the the event I need or am forced to land somewhere I can't identify the surface.
https://vimeo.com/244235229
Barnstormer offline
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Re: Lessons from learning to Ski Fly

Hi Phil good to see you're experimenting. Question please...what's on the bottom of those skis for skegs and surfacing? You seem to be having a particularly tough time getting the plane to move which really shouldn't be the case in my experience. Yes ice and frost can increase surface roughness but if the skis are blocked up off the surface below between flights they should stay clean.

Are the bottoms smooth? Are the bottoms the same material as the upper surfaces? Does snow stick readily to the tops of the skis? I just have no experience with carbon fiber. If there's wear bars or skegs what are they made of and are they smooth? Are the brakes fully retracted and not grabbing the ground, or being extended unintentionally via rudder application?

Another way to break them loose prior to flight is grab the lift struts at the wing attach points and rock the plane's wings up and down. Vigorous action that lifts and moves the skis relative to the surface that can dislodge debris and free the skis.

If experiencing flat light then source and wear some blue blocking orange or yellow glasses like skiers or trap shooters wear. They can enhance visibility and increase contrast enough to see the snow surface better. I wear ambermatic photosensitive prescription lenses that work like the shooter's lenses.

Carry some rolls of bright surveyors tape to throw out on the snow if you need ground reference. I there's a breeze they will blow about making them easy to see. Try different colors from a distance on the ground before to find the best contrast against the snow in flat light. If you frequent landing spots hang some tape from the shore's brush to note the wind.

Gary
Last edited by PA1195 on Sat Nov 25, 2017 5:14 pm, edited 1 time in total.
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Re: Lessons from learning to Ski Fly

Thanks for posting this. I'll be doing my first ski flying later this winter, so I'll be following this closely as you add additional lessons. Thanks also for the heads-up on MTV's post.
Brian M offline
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Re: Lessons from learning to Ski Fly

Good work, Phil.....and a great start! Getting stuck, unintended turns and flat light all in your first few adventures is a bit unusual, but you’re taking those challenges on and learning what works. Just be careful with flat light. Very low sun angles at this time of year, so any clouds can cause bad light. Gary’s comment on glasses may help. I never liked those glasses, but they do help in flat light.

I’m with Gary on the questions why your skis (or just one) are sticking. Are you parking the skis directly on the plywood? If you don’t have some sort of skegs, the bottoms of the skis may be freezing down to the (damp) plywood.

You might try putting a block of some kind under the skis, just forward of the pedestal. That’ll allow Air to circulate under the ski bottoms.

That said, I have no experience with ski bottoms made of carbon fiber. Are your bottoms carbon fiber, or some version of UHMW? The Rosti retractable are carbon fiber, but the bottoms are still UHMW. I would expect carbon fiber bottoms to not freeze down, but have no experience with that material on bottoms.

Anyway, it’s always a learning experience, no matter how well you prep.

As you figured out, trying to taxi out of a Hangar can be very risky. I rigged up a rope harness with a loop on each end, and one in the middle. Run each end inside the ski pedstal, and bring it around to hook over the axle. With each end thus connected to a gear, drop the middle loop over the hitch ball on a truck, and gently drag the plane out of the Hangar. That will also break the skis loose from that plywood.

Keep having fun, and keep us posted. I love those videos!

MTV
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Re: Lessons from learning to Ski Fly

I did a brief search for bases of skis and snowboards made from carbon fiber. When all ya got is gravity slick counts. Most if not all use some other material than the carbon fiber as a bottom...UHMW (various types: https://www.backcountry.com/explore/ski ... -explained) and various polyethylene compounds waxed in addition (https://snowboardingprofiles.com/extrud ... st-for-you). Any surface porosity can create places for water to freeze so the smoother the better. Skis and ice skates create a thin film of water from pressure that reduces friction, but that water can and will freeze to the bottom of skis and slow or stick them.

If there's any metal exposed or metal runners they can be replaced with UHMW. So let's find out what's on the current ski bottoms and go from there.

Gary
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Re: Lessons from learning to Ski Fly

Thanks for the pointers and tips everyone. The bottoms and skegs are UHMW. Here is a pic. I even waxed them before I put them on and made sure I bought the slippery ski wax. Sure is a bunch different from bush wheels, and a lot more work. I don't get my new truck (just had to go back to a Raptor) till probably late January so I'll be fighting it till then. I do have a four-wheeler winch mounted on the hangar back wall, which I use to pull it back in. Been thinking about mounting a second one opposite the hangar on the outside of the garage to pull it out. Maybe I should do that.
And yes, it sits on mostly bare plywood.

Speaking of pulling, on a cub where is the best place to attach to the back too pull? I'm using one of the cross bolts on the T-3 which I know isn't good.

Lesson- the snow changed a ton in two days, one of those days the wind blew 20-30 knots which moved the powder significantly, plus ice fishermen, ice skaters, four wheelers, ski machiners, wheel planes and ski planes all came out at the same time and rutted the lakes up. Lots of overflow can be seen on most lakes that the powder had been hiding or isolating from my skis. I shot a video today and will get that up soon.

Thanks again everyone. Keep the thoughts, pointers and tips coming- they are greatly appreciated.

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Re: Lessons from learning to Ski Fly

Oh...

Gary,

I've got some yellow clipons on order, should be here soon.

Like the idea of surveyors tape, I'll pick up a bunch of rolls.

MTV,

Brilliant idea with the rope tied to the pedestals, I can take a long rope and do the same pulling it backwards can't I?
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Re: Lessons from learning to Ski Fly

If black UHMW they are quality bottoms but I like to see the fastener heads countersunk a bit if not already. That metal can attract frost and having them sucked up a bit in the skeg material and covered with RTV or something inert helps.

All weather wood is sticky stuff so maybe put something slick on top of the plywood. A blue tarp would work for awhile but plastic's better. If it's below freezing and stays that way water will coat it. Old time dog mushers used to P on the metal sled runners if the dogs didn't.

You should be able to move that plane easy with power in that little snow depth. If there's any chance for the ski brakes extending unintentionally block them up temporarily and see if it helps.

Do you plan to compress and drag the movement area and strip? Helps get around and smooth the ground run...no point in having the skis jerked sideways by ruts. Snowmachine and drag will do it.

Screw or drive something flush with the ground in front of the plane. Clip a pulley to it and thread a rope though with a ski bridle. Hook it to the winch and pull yourself out.

MTV: Your camp at Mucha changed hands and a friend with a C-185 is now using your outhouse and killing bears as part of the Kantishna area's moose survival management project. BTW Leonard N. passed and their camp will be sold.

Gary
Last edited by PA1195 on Sat Nov 25, 2017 10:10 pm, edited 1 time in total.
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Re: Lessons from learning to Ski Fly

Great ideas Gary, thanks. I will implement them. I’m making sure to keep my feet off the brake pedal, especially when I’m trying to move the plane. But even if it were down (and I have checked that) I don’t think it would have any affect as it’s just two carbide tips.


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Re: Lessons from learning to Ski Fly

Phil
I saw your tracks in the lake today when I flew the 180 down!! I think the problem you have with turning is the the tailwheel was not locking in. I had the same issue when I started with skis. As you come out of a turn (tailwheel is unlocked) as you straighten out double kick the rudder RIGHT, LEFT, RIGHT or LEFT, RIGHT, RIGHT, to relock the tailwheel. The rudder alone is not enough to overcome the P factor.
DENNY
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Re: Lessons from learning to Ski Fly

Barnstormer wrote:Great ideas Gary, thanks. I will implement them. I’m making sure to keep my feet off the brake pedal, especially when I’m trying to move the plane. But even if it were down (and I have checked that) I don’t think it would have any affect as it’s just two carbide tips.


Ok Phil just checking on the brakes. I've seen but not used them and they look well built and effective.

Part of having a wide ski with relatively flat bottom is eventually we end up fighting resistance to movement from width (think pushing like a plow and compacting snow in front which takes energy) plus whatever additional friction a large flat surface has over a cupped one with less direct area under pressure.

In addition any non-parallel alignment of the skis (often unavoidable do to spring-bungee tension) creates drag from the offset vector of the skegs and ski sides. Your sides are nicely rolled up (good) but still take a tape and measure front to back distance across the skis to see if they're toed in any. Less is better and varies with supported weight and gear geometry.

This vinyl thread-imbedded material is good slick stuff and tough if you want top temporarily cover your plywood or just fasten it directly to the ground: http://alaskatent.com/covers/grillcovers.html They use it to make covers and a variety of things...very useful and stays flexible in the cold. I hang a curtain made of this behind my Taylorcraft's seat in the winter to keep me warmer.

Let me ask you this. If you stop on a lake or strip how much power (rpm/MP) does it take before you move? I don't know the engine or prop setup. You should be able to rip the skis loose at will even if you have to bounce the tail a little to get them moving after stopping.

Gary
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Re: Lessons from learning to Ski Fly

DENNY,

I removed the steering mechanism from the Tailwheel. I’ve actually been wondering if it would be better to put it back on.


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Re: Lessons from learning to Ski Fly

PA1195 wrote:Let me ask you this. If you stop on a lake or strip how much power (rpm/MP) does it take before you move? I don't know the engine or prop setup. You should be able to rip the skis loose at will even if you have to bounce the tail a little to get them moving after stopping.

Gary


Gary, except the first time on the first day, when the powder did pile up in front of the ski, I haven’t had any problem getting moving again. I’ve also not been in 12” snow again either. It starts moving pretty easily. Enough that I can’t do a prop or mag check without the plane moving.


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Re: Lessons from learning to Ski Fly

These are great problems to have.
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Re: Lessons from learning to Ski Fly

Phil,

It seems to me the most likely culprit to getting started out of your Hangar is that plywood. If it were summer, you might be able to coat it with epoxy or something else slick.

At this point, if you can’t drag the plane out with a vehicle easily enough, I’d consider buying a sheet of thin UHMW, cut it in half and fasten that to your plywood. Kinda spendy, but so is the potential for damage otherwise. That should make it super easy to slide in/out.

The rope harness I described always worked for me, dragging a Husky out of a heated hangar on straight skis. I used a winch as you described in the back of the Hangar to drag the Plane back in. I just used a standard chain type hook, and hooked it over the tailspring leaf. Did that for years and never had any issues. The floor was epoxy coated, and skis had UHMW skegs.

I’d be afraid that trying to used a main gear attatchment to slide the plane into the Hangar would turn into a goat rope. Think tailwheel with a mind of its own, and tail going every which way.......$$$$$.

MTV
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Re: Lessons from learning to Ski Fly

The aircraft skis shown have a low aspect ratio. Which will make them hard to move (or start to move) and get stuck in powder more so than a high aspect ratio ski. The longer the waterline the deeper the powder the ski (vs weight) can move with applied thrust.

Example: Skiing downhill, I learned that in deep powder snow, it was much easier to ski a longer ski with reverse rocker than a shorter ski designed for conventional packed snow. Last year we got 57' of powder at the ski area. Generally I ski a 190cm/88 in powder.
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Re: Lessons from learning to Ski Fly

I made up a pulling ring that bolts onto my main tail spring (in my case, a J-3 type) bolt, it serves as my rigging point when I need to pull my S-7S backwards. When pulling it front I too use a bridle that only stress the planes where it can take it. Having rigging points front and back is for sure a must have for a ski plane, on wheel skis or not, sooner or later!

I'm enjoying your education Phil, you will have a renewed appreciation for your brakes when you get back on the wheels, you will never think harder flying then when setting up a ski landing in a new area, at least that's how it works for me, and be advised it is very easy at first to get all caught up in the LZ thinking, while forgetting that the turnaround to get out is the BIG thing with ski flying, landing is the easy part.

No snow here yet, but I have my small tires on, ready for the Datums, your struggles with getting your bird in and out of the hangar remind me why I paved the area outside my door, and have a blower on my tractor, and have wheel skis. I sure would like the simplicity of straight skis, I just couldn't figure out how I could make them work for my mountain strip ground handling.
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Re: Lessons from learning to Ski Fly

Parking the skis on cheap carpet sleds helps. They roll up (if you want to take them with you) and don't stick.

https://www.walmart.com/ip/Flying-Carpe ... /618823195
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Re: Lessons from learning to Ski Fly

Phil
Yes put the tailwheel chains back on. I thought that was the problem to start with, but I looked close at the video and thought I saw them on the plane. I would also strongly recommend a penetration tail ski.
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Re: Lessons from learning to Ski Fly

Something like these wheel dollys make repositioning and frost free easier. Install a pinned stub in the axle if it's still hollow. If solid then add a sleeve adapter below? I have a set on 2000 Aero's and they work as advertised.

https://www.youtube.com/watch?v=3MbRpkT5-a0

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