Snowplane test on snow !!

OVERLORD Fri Feb 01, 2019 11:16 am

Remember this thread??

https://www.coxengineforum.com/t7323p50-snowplane-radio-gear

Last night it started snowing over here. Usually, the next morning it all disappears but when I woke up today, the snow was still there. That was THE occasion to test the snowplane again, but now on snow. The engine hasn't run for a few years and I had to free it with my small gas torch. The engine ran but the revs didn't remain constant due to dirt or castor I guess.

When trying on soft snow, it sinks too deep in the snow and digs itself in immediately. Running it on the driveway was better. It needed top revs to proceed. Once the revs went down a little, it stopped. That means that speed control by RC is impossible. The 3 skis give too much resistance for the engine. Maybe a TD would be better or fix a sort of skates under the skis and run it on ice.

A short video:

https://youtu.be/4P8HYx7o-I4

1/2A Nut Fri Feb 01, 2019 12:25 pm

Yep agreed, looks like it will need a TD .049 or Medallion .09 with throttle sleeve to overcome the drag induced by snow.
Over the iced up bits it was able to get some movement. Nearly there keep up the good work with enough power it will
jam out over the snow and climb up elevations, should be some real fun!

Thank you for sharing Overlord! Thumbs Up

KariFS Fri Feb 01, 2019 1:17 pm

I remember that project, very nice craftsmanship, beautiful result too!

One thing you may want to try is to use a light spring or a rubber band to pull the front ends of the skis upwards. That might prevent the skis from diving in the snow.

During the wars, the Finnish Air Force used a lot of ski-equipped planes, and they had such a system, of course there was a rope or cable attached to the back end to limit the movement of the skis. For a surface vehicle such a limiter would be unnecessary, but in an aeroplane it was necessary to prevent excessive upwards movement when airborne, as the skis would then cause unnecessary drag.

I guess you could also play with the engine angle and CG too, just as with flying models.

Although, even the ”real” machines did not like too much soft snow, but worked best on a beaten path.

Edit: Here is a photo of a familiar looking full size sled. It is a Soviet unit, captured by the Finns during the Winter War. (Please note, our insignia was a blue swastika in a horizontal position, it had been in use by our Air Force since 1918, long before the German nazi party with their diagonal black one even existed)

balogh Fri Feb 01, 2019 1:29 pm

Bravo Overload it is a real fun!!

**Cribbs74** Fri Feb 01, 2019 2:39 pm

Did you wax the skis?

Marleysky Fri Feb 01, 2019 4:39 pm

Hello Lieven! Nice video. Ron Cribbs had the same thought I did while watching your Snowplane. Waxing up those skis will let it slide a lot smoother. Or, like you mentioned a set of skates for use on ice will reduce the friction. You definitely need more power or less resistance!

getback Sat Feb 02, 2019 7:16 am

Glad you got a chance to run it again , it was a really cool project and ur right on the edge of getting it running up to speed . Thanks for sharing Snowman

rsv1cox Sat Feb 02, 2019 7:52 am

Yes, I sure do remember that thread Lieven. Beautiful work. Enjoyed the video, and yes wax those skis. SOP for our skis in NH.

Like silk in a muzzle loader as depicted in "The Last of the Mohicans". According to Hawkeye - "Adds 15 yards."

Bob

OVERLORD Sat Feb 02, 2019 1:26 pm

Thanks for your comments. No, I didn't put any wax on the skis, as I don't know anything about skis or skiing. I'll look out for that.

**Cribbs74** Sat Feb 02, 2019 4:46 pm

There probably is wax available that is specifically designed for that purpose, but as A kid I would just melt parrafin wax on my skis. It worked well and made a huge difference.

roddie Sat Feb 02, 2019 7:10 pm

Cribbs74 wrote:There probably is wax available that is specifically designed for that purpose, but as A kid I would just melt parrafin wax on my skis. It worked well and made a huge difference.

Ron is likely referring to "Gulfwax" which can be found anywhere that "canning-supplies" are sold. It is a parrafin-wax used (melted) for sealing glass-jars containing prepared fruit/vegetable preserves for storage and also for candle-making.

GallopingGhostler Sun Feb 03, 2019 7:50 am

Cox .049 reedie doesn't have enough thrust to propel it for RC throttle use. Weight of the model and drag of the skis show it is underpowered. I'd go with at least a Medallion .09 RC or another make engine in the .09 - .10 range. You'd have to modify the pylon so a small tank of at least an ounce could be mounted behind the engine (towards front of the car). Rotating the nose on an Enya .09-III or IV 90 degrees would reverse its direction and allow you to use standard tractor props instead of pushers.

KariFS Sun Feb 03, 2019 9:53 am

OVERLORD wrote: I don't know anything about skis or skiing.

Lucky you

Skiing and playing the flute were my least favourite things at school. Old traditions, very unnecessary in today’s world. Never was able to learn the flute, but I guess I am ”above average” in skiing if the population of the whole world is considered Very Happy

As the bottoms of the skis are probably pretty smooth, I think something like a proper car wax (carnauba or other ”solid” stuff) would do. The friction between the snow and the metal is pretty high, the sliding happens because the snow melts in ”micro level” underneath the ski. The wax will reduce the friction between the water and metal. Also, if you bring the skis from inside, and lay them on the snow before they have cooled, the snow may stick on the bottoms.

Also the rubber band thing that I wrote about earlier might be worth a try. The small force that pulls the front end up, works as a counter effect to the friction that tries to push the front end down. Theoretically you would get more even surface pressure under the ski and also prevent the front ends from diving in the snow.

About the engines, a Queen Bee would be a little more powerful and still a reedie, so it would run backwards too. Even with the Dragonfly it moves pretty nicely once you get it moving, so maybe it would work ok just by tweaking the skis Huh...

roddie Sun Feb 03, 2019 12:27 pm

Hi Lieven! It's great to see you running this model again! Keep in mind that snow "texture" varies to a LARGE degree. If you lived in an area geographically where there are colder temperatures during Winter, you could see much better performance from that model.

I browsed-back through your original thread where you posted a video of the snowcar running on hard-packed gravel. There was no problem. The snow that you're running in now, is probably "warm/wet-snow".. which would impose a high coefficient of drag on those untreated skis. It's almost like putting two-sided adhesive-tape on the bottoms. Try the wax.. any type that you can find, and you should see a marked improvement. I believe that your current engine has plenty of power.

One more thing to consider; I don't know what you're running for a propeller now.. but do you have any rigid (competition-style) 2-blade props having a 4" pitch.. and a 5" (or smaller) dia.? I don't think that softer-compound (safety) propellers would be a good choice for this application; as they tend to run "shy" of their rated-pitch (because of torque-flexing) when running-up into the engine's power-band. This isn't as critical with an aero-application.. because the engine/prop will "unwind" once the airplane gains speed. Your model needs continuous true-pitch on those blades to push it along.

I will add this final thought.. Remember to mount a "tractor" propeller facing forward for a clockwise rotation on a rear-facing engine. Two Cents

OVERLORD Sat Feb 09, 2019 2:19 am

The prop that's actually on the engine is a 3 bladed 6x3 left hand prop. I think it's a Grish/ Tornado. The engine has the power for sure, but at maximum revs only. Any speed variation seems not to be possible, the model will just go or stop. Therefore, a TeeDee would be better. I'll need to experiment with that.

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