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It's That Time Of Year Again: Snow Skimmer Challenge!

Ryan O.

Well-known member
Wow all you guys with lots of snow and quick build times are so bored with this thread by now. :rolleyes:
Ok, a little progress here. Building up the tail, and now I need to build motor mounts on the vertical stabs. I'll try to just get it done at this point. Freezerburn don't care. It would be a crime to miss the next snow without having the chance to put all you guys to shame with my ridiculously fast little red rocket ship.
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I've been looking for a good glue to glue posterboard to PETG. I haven't found any good options that work well in cold besides maybe 5 min epoxy, but I haven't had an opurtunity to try that one yet :I
 

Monte.C

Well-known member
I've been looking for a good glue to glue posterboard to PETG. I haven't found any good options that work well in cold besides maybe 5 min epoxy, but I haven't had an opurtunity to try that one yet :I
A quick search (you probably know all this) shows me CA and Gorilla Glue. I know CA works with paper products and I have on hand foam-safe CA too. They're telling me Gorilla Glue works on PETG too. I would sure want to cut the surface with sandpaper...
But yeah you know these things. :)
 

Monte.C

Well-known member
Oh in some situations, where you can, if you're unsure of the bond strength over time you might drill a couple tiny holes for the glue joint. So the glue gets into the hole and helps with a mechanical joint to help the chemical bond. (y)
But you know what you're doing as much as I do.
 
The other day I found a patch of Ice to run my speeder on that I just couldn't pass up. It was a perfect runway of ice for the speeder with enough length to get to the speeders top speed! Anyways I got a short vid of the runs, I'm hopping the pure speed of my craft comes across in the vid. Enjoy!
Looking good, I had to take a quick break from mine to build a corsair for someone else, but I should have pictures of skme more 3d printed parts soon
 
The other day I found a patch of Ice to run my speeder on that I just couldn't pass up. It was a perfect runway of ice for the speeder with enough length to get to the speeders top speed! Anyways I got a short vid of the runs, I'm hopping the pure speed of my craft comes across in the vid. Enjoy!
So you only have those skids up front, the tail is flying?
 
Is there a specific EDF diameter to thrust tube length to end of thrust tube ratio for maximum efficiency, or is it just a best guess? Also, is there an intake to EDF diameter ratio as well? Thanks.
PS, I'm either going to paint v2 like an antarctic exoedition vehicle or with some corny italeri race scheme because, you know, gotta go fast.
 
Is there a specific EDF diameter to thrust tube length to end of thrust tube ratio for maximum efficiency, or is it just a best guess? Also, is there an intake to EDF diameter ratio as well? Thanks.
PS, I'm either going to paint v2 like an antarctic exoedition vehicle or with some corny italeri race scheme because, you know, gotta go fast.
In my testing, thrust tube length has little to no effect on static thrust. For maximum performance, make sure the thrust tube starts to taper only once aft of the motor bell housing. Also give a good radius on any inlet surfaces to prevent flow separation.

There's a parameter of the EDF called the "Fan Swept Area" (FSA) which is the area of the circle swept by the blades minus the area taken up by the spinner/motor. Inlets are typically around 100% FSA. Bias this number higher for longer ducts to counteract boundary layer losses and to improve low-speed performance at the expense of high-speed performance, bias it lower to improve high-speed performance at the expense of low-speed performance. Outlets are typically around 90-95% FSA. Bias this higher (but never exceed 100%, after which performance degrades in all flight regimes) for more static thrust (better low-speed performance) or lower for better high-speed performance - typically, this ends somewhere south of 85% and will vary from unit to unit.
 

Monte.C

Well-known member
The other day I found a patch of Ice to run my speeder on that I just couldn't pass up. It was a perfect runway of ice for the speeder with enough length to get to the speeders top speed! Anyways I got a short vid of the runs, I'm hopping the pure speed of my craft comes across in the vid. Enjoy!
With that flying tail it looks like a bit of a balancing act. Did you have any trouble with pitch?
 

Monte.C

Well-known member
i was out trying today, but must forget to do it on road here, its not long enough for 5 sec Need try out on the RC field one day, where its snow, and perhaps longer.
I suppose this should be following the rules , without wings on. 70mm EDF, 6S..... (its fast at least...)
Wow! Looks like a sci fi craft from the 50s or something. If that performs for you, well that's just amazing.
 

leaded50

Well-known member
With that flying tail it looks like a bit of a balancing act. Did you have any trouble with pitch?
With the wings and elevons, its no problem, but even seems get the correct angle on the front wing/canard. Problem on icy road sleight test without wings, was that the hull have a v-shape bottom, and with no wings with spoonsons to stabilize, well....
Its a jetfighter flying boat design proposal form a Mr.Bartini (italian/russian) aerodesigner. A single scetch made at start of the 50´s. Some guys are making a book about the designer, and i was shared a little info, eg. a 3D rendering of this plane..... typical me, this looked as i needed try make it :LOL:
https://forum.flitetest.com/index.p...-seaplane-fighter-proposal-of-the-50´s.65626/
 
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Monte.C

Well-known member
With the wings and elevons, its no problem, but even seems get the correct angle on the front wing/canard. Problem on icy road sleight test without wings, was that the hull have a v-shape bottom, and with no wings with spoonsons to stabilize, well....
Its a jetfighter flying boat design proposal form a Mr.Bartini (italian/russian) aerodesigner. A single scetch made at start of the 50´s. Some guys are making a book about the designer, and i was shared a little info, eg. a 3D rendering of this plane..... typical me, this looked as i needed try make it :LOL:
https://forum.flitetest.com/index.php?threads/bartini-jet-engined-seaplane-fighter-proposal-of-the-50´s.65626/
Yeah but I imagine it in more than an inch of powder. Imagine how it might bank through turns! Or not, you might just get adverse roll. I won't know until I see it, but it's so easy to see that as a slick snow boat.
 

Monte.C

Well-known member
With the wings and elevons, its no problem, but even seems get the correct angle on the front wing/canard. Problem on icy road sleight test without wings, was that the hull have a v-shape bottom, and with no wings with spoonsons to stabilize, well....
Its a jetfighter flying boat design proposal form a Mr.Bartini (italian/russian) aerodesigner. A single scetch made at start of the 50´s. Some guys are making a book about the designer, and i was shared a little info, eg. a 3D rendering of this plane..... typical me, this looked as i needed try make it :LOL:
https://forum.flitetest.com/index.php?threads/bartini-jet-engined-seaplane-fighter-proposal-of-the-50´s.65626/
I got it! I bet if you coordinated ailerons in the canard with the rudder you'd have the perfect snowboat. Maybe that's my project for next year!
 

Ryan O.

Well-known member
Started work one the trimotor. I want it to have a its thrust as centerlined as possible, so the center ducted prop will end up 1.5 cm over centerline and the outboard ducted props will be about 2 cm over centerline. This is to make up for the shape of the fuselage which should create a pitch up tendency. There will be next to no Lipo space for the board and receiver, so any balanceing will be done with weights, but that's the price you pay for speed :) I'll have to make the extensions for the outboard motors 3d printed to reduce drag. So far I won't give the outboard ducted props long thrust tubes to save on weight and for simplicity. The center motor should have a longer thrust tube. It'll also need 2 extensions from the fuselage sides to keep it rigid, likely either wire or 3d printed.
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Think of the floorboard lines as the ground.