Project started on September 3rd, 2009 Web page built out on October 4th, 2009; thanks for visiting!

The SKYCART is a novelty 'Flying Gocart' design posted to this SCKCART build and discussion thread The Foamies-Scratchbuilt section on RCGroups I started following it at the forst of September of 2009, and started posting about my own Skycart build in page 26, post 390.

Above: Final setup on my Skycart. The rear axles are mounted about 1-3/4" out to the rear from the hinge line on the elevons.

Above: When the elevators are deflected up, the rear end of the 'cart "squats, enabling it to do a ROG take off easier

Above: When the elevators are deflected down, the rear end of the 'cart is raised, increasing ground handling response.

P>Above: Here's a look at the narower Aquarider wheels that I am running on my Skycart- I had the material on hand, and I didn't have any thin EPP around right now. I expect that they'll hold up well, and they are light & resilient.

9-03-09: First step - making the wheels.

A couple of years back, the 'AquaRider' Pool floatation toys were available for one season; they were made of EPE (Expanded Polyethylene) , just over 3/4" thick, 6" wide, & at least 4 feet long. We used them for the body / fuselage in the Woodstok variant of the Blue Beagle, & about 30 of the Beagles were built using this foam. It worked fine for the job. It really only glues well with hot melt glue- even CyA glues don't grab to it very well or hold for very long; it's molded from the same material as Polyethylene bags, after all! It is tough & resilient, and is responsive to heat-shaping techniques.

I had some of the AquaRider material left on hand in both blue and yellow - (I haven't heard of it being available recently) - so I cut a set of light wheels to try on my EPP Skycart. I used 1/32" birch ply side plates, 3/4" square, on each side of each wheel, mounting the ply with hot melt glue.

The full set of 4 wheels weighs in at a total of 18.3 grams. I actually made the final front wheels 4-3/4" diameter, and the rear wheels are about 3-3/4" diameter, to give the deck a bit of positive incidence when running on the ground, so it won't take quite so much rear end 'squat' to get it to ROG.

My front axle is flush with the lower surface of the 9mm EPP foam deck / wing, so I have roughly 7/16" positive incidence on the deck when running these wheels with the elevons roughly trimmed level. Based on flying my SUMO with the landing gear, that is not enough positive incidence to ROG, so it should run well on the ground; but it will not take as much rear end 'squat' to lift off the ground when starting from here.

I've been using the SCOTCH Extreme cross-filament nylon filament tape for hinging control surfaces on bare EPP for the last few years, and it has bonded well and held up well; it has some of the most agressive adhesive of any tape that I've used. I even use it to hinge the ailerons on my combat slope ships- it's close to indestructable!

I'm flying my SKYCART with a 1700Kv 24 gram 'Blue Wonder (Hextronic) motor on a 2S 460 mAH RHINO battery pack with an 8" prop.

The 9mm thick 1.3# density EPP which I used for this Skycart is working well. I used a flat CF strip spar just 3/16" in front of the elevon hinge line, inserted into a slit in the foam so it's saet vertical & flush with the upper surface. I used Cya thin glue to glue it in the slit. I mounted the 3mm O.D CF tube front axle at the lower edge of the EPP at the front of the wing / deck.

By using a covering iron set to low heat to iron down the cross filament nylon filament tape, you get an incredibly solid bond to the raw EPP, so it works great for hinging, etc.

Above: I first built my SKYCART with separate servos controlling the wheel axles, controlled from the radio system's flap position switch. It was awkward to operate, however, so after some test flights, I removed the two extra servos. I'm using a pair of HXT900 servos to control the elevons now; the wheel carrier sections of the elevons are tied to the main elevons with Scotch Extreme cross-filament tape. I'm prefering the simplicity of flying this setup. But it was an interesting experiment to try.


9-05-09: I installed the motor on the incidence line drawn on the plans. In the air, it was acting like it had too much positive incidence on the motor mount... it was needing negative elevator trim to handle higher throttle settings, even when the balance was shifted forward, & it was wallowing around too nose-high. [Translation: the motor & elevons were fighting each other!]

I had mounted a bulkhead motor mount with three screws, so I added two .5mm thick washers behind the mount's top mount leg. This improved the flight performance quite noticably! I may yet add a third shim washer and test fly it to see how it handles with even a bit less positive motor thrust line.


I'll comment that I personally prefer the in-flight handling better with the balance forward at the origional specification of 5" back; I'm not much into hovering or wallowing around with the nose high up in the air... just never got into that much... it's just a personal preference thing, I guess- I'm an outdoor flyer in the thin air of Colorado's high country, after all.... For more axial rolls & higher speed forward flight & handling gusty wind flying conditions, the forward balance point seems to have the advantages.

9-06-09: After test flying, I got after finishing the dress-up work. Weight dropped to 7-1/4 ounces with the extra two servos removed, ready to fly with the 2S 460 battery installed after this work, before the final dress-up painting was done

The photo above shows the result- a 'Midget Dirt Track Racer' version that I generated free-hand. This grinning driver has a red full dress body on this machine, with an enclosed rear engine with plenty of cooling air flow via the top air scoop & exit slots.

Thanks to Larry Ross for the cool wheel rims! After painting the Aquarider foam wheels with Plasti-Kote's "Odds-N-Ends" black spray paint, I cut out the rims from the printout, turned them over, and applied three thin rings of hot melt glue to the back side. I let the glue cool first, then used an axle-sized piece of scrap material to align them in place on the center of each wheel. I then used a covering material iron set at ~250 degrees F. to bond the rims to the wheels. The result is as you see them- definitely dresses up this Skycart!!

The paint and wheel rim trim added 3/8 ounces to this Skycart, so final flying weight, as shown in the photos, is at 7-5/8 ounces. (After thorough drying of the paint, it later weightd in at 7.5 ounces.)

I briefly tried an APC 9x3.8 prop on the 1700Kv B.W. motor; it loaded it too much- poor performance- so I quickly returned to the GWS 8043 SF prop. This one seems nicely matched to the motor when running on the 2S 460 packs.

Above: Skycart flying against a dramatic sky with Silverheels Mtn. in the background

9-07-09: I'm enjoying flying my Skycart as it is; it does decent ROG takeoffs when flying from a decent dirt road or similar surface. One little tweak I do intend to implement right away, however...With my latest set of much larger front wheels, I am observing that it's handling like it's getting a bit short on rear vertical stabilizer area... so I'll likely add some more rear stabilizer area to the rear this AM & see how it affects the flight characteristics. I'll post a report on the results.

I had the short center under fin even with the bottoms of the rear side rail skirts, so it didn't extend any lower than the low points that were in the design already- I had added just enough there to protect the lower end of the rudder which also extended below the deck ~1/2". But as you so aptly pointed out, it is one more extension below the deck to catch on anything when the rear end 'squats' to take off- which it will definitely do in grass.

So while chopping it off flush with the deck where it could not catch, I also looked again at the side skirt pieces; they also limit how low the rear end can squat when doing an ROG takeoff. (Trapping air under the deck may not be quite as important as being able to drop the rear end of the deck without dragging on the rough terrain up here...) So I trimmed the rear ends of those within 1/4" of the deck at the rear end, tapered the trim line forward for the rear 6".

The results were very gratifying; it'll now ROG easier, with less or a run on flat ground to get up to a good rotation / liftoff speed.

Outside loops are insanely tight. Roll rate is quick, and rudder response is very adequate.

The oversized tires I had built for the front end of my Skycart definitely added a lot of area forward of the CG that wanted more counteracting rear vertical stabilization, so I added a couple of 6mm EPP fins on each outside edge of the rear end of the deck. This worked very well- I can now fly it into & back out of any insane attitude & maneuver (inverted flat spins, tumbles, etc.) Recovery from any crazy antics is now quick & predictable. Air was really irregular & gusty this morning as I was doing the last test flying, but that's really not an issue now. It's all fun!! Again, Leadfeather, thanks for all of your inspirations & tips!!

Above: Final setup on my Skycart, with the side fins at the rear edges of the wing / deck added.

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