Ready for trial flights.
|Wing Area:||382.5 sq. in.|
|Wing Loading:||5.45 oz/sq. ft.|
|Transmitter:||Hitec Flash 5X|
|Receiver:||FMA Extreme 5|
|Battery:||Great Planes Electrifly 1500 3S LiPoly|
|Motor:||Great Planes Ammo B20 (3600 KV)|
With the advent of inexpensive brushless motors and lithium polymer batteries, electric flying has taken an exciting new direction in the last couple of years. This new direction is what I call "backyard 3D". Using Depron foam, extremely light and durable profile models are easily kitted and assembled. Throw in a little carbon fiber along with those awesome electric components now available and you've got a ridiculously overpowered fun machine. Foamwing has been on board during this revolution and done a lot of R&D to bring you their ultimate offering in this category. They claim that if you have a brushless motor, this is the plane to put it in. Since Great Planes had previously offered up a new B20 class motor for review, the Ammo, I decided to put Foamwing's claims to the test!
The instructions that came with Slipper II were for the original Slipper, but after a quick email I was able to download the preprodution instructions for this kit. I also found out that there will be two versions of the kit available. The first, like mine, will be the basic kit with only the depron parts. This kit would be good for the experienced modeler who prefers to do things their own way. The price for the basic kit will be very reasonable. After printing out and taping together tiled plans, then cutting out the parts from fanfold, the price for these nicely done depron parts seemed really reasonable! The second version will be a deluxe kit that will include all the hardware needed to complete the Slipper II.
These types of planes are not for the beginning builder or flyer although they are fairly easy to assemble. However, setting them up correctly and flying them is not easy and requires substantial experience. In light of this I won't bore you with a lot of text on construction. Instead I present a series of pictures with captions noting my style of setting up this kind of plane and any problems I encountered.
I went for as much throw as I could get on every surface when setting up the servos and linkages. I acheived at least 45 degree deflection or better on the rudder, ailerons, and elevator.
Great Planes only specified the Kv of the Ammo motor (3600). Without the other two specifications, idle current and resistance, I couldn't run computer simulations and didn't have a clue what gearing to use so I could continue to swing a GWS 12-6 prop and use the Electrifly 1500 3S.
All E RC came to the rescue with their new gearbox including extra gearsets. Using my whatt-meter I tested the 5.33:1 gearset first. I tried this ratio first because the Ammo had a lower Kv than my MM MiniAC that had been previously tested at a gearing of 5.82:1. Even though the Ammo had a significantly lower Kv than the MM MiniAC, the whatt-meter showed a static current of 18 amps!! This was barely within the motors limits, but the 1500 3S battery was only rated for 12 amps.
I switched to the next higher gearing of 6.6:1 and was rewarded with the acceptable current draw of 12.8 amps static. I knew that the prop would unload in the air and reduce the current. I also knew that a hover would only require approximately half throttle, so this current draw was fine. For more information on the Ammo brushless motor setup in the Slipper II, see my Great Planes Lipoly review recently published here on The E Zone.
After a few passes on the first trial flight, it was clear that the Slipper was nose heavy. Rolls weren't axial at all and required a lot of down during the inverted part of each roll. There was no way to move the battery any further back because it was already up against the aileron servo. I ended up changing the orientation of the battery to the long dimension running with the wingspan. This moved the battery mass substantially toward the tail.
On my next outing with the Slipper II it was very close to neutral stability with the new CG. Just the slightest input was required for rolls and sustained inverted flight. I would have liked to try moving the CG even more, but it's structurally impossible with the current placement of the aileron servo, short of adding lead. Foamwing designed this plane to be used with an ETEC 1200 3S which weighs less than Electrifly 1500 3S pack I used. I'm sure this was the cause of the CG problem.
With the plane tuned, it was time to put the Slipper II through it's paces. Rudder and aileron authority was excellent! The 45 degree or better throws on all surfaces provided excellent control without making the Slipper II twitchy at all. Upright flat spins were no problem, along with slow knife edges. The Slipper II held it's own in a knife edge and I detected no coupling that would require inputs. Rolls were very close to axial, snaps were very crisp and pleasent to watch. With the new CG, the Slipper II didn't care whether it was upright or inverted.
The Slipper II is my second flat plate 3D foamy. The first was a free plan on the E Zone called the 3DX made from FFF. I beat that poor thing to death learning to hover and harrier close in. One thing that disappointed me about the 3DX was that I could never stop the serious wing rocking during high alpha maneuvers. The Slipper II made that all go away! It had absolutely no wing rocking and is super solid in a high alpha attitude. Harriers with the Slipper II are a joy (especially since that's my favorite maneuver at this time). They were slow and solid no matter how high I held the nose. I could even sneak into a hover by just slowly increasing the angle of attack while doing a harrier. Hovering the Slipper II is a snap compared to my first flat plate foamy. It was easy to get it into the groove and easy to keep it there. It torque rolled very nicely and would float with the wind while doing the maneuver. Because of the Slipper II's stability and ease of inverted flight, inverted harriers were very easy. I haven't mastered rolling harriers yet, but as stable as the Slipper II was in high alpha positions, I'm sure that the advanced 3D pilot could do them well with this plane.
Obviously the Slipper II is not for the beginning flyer. However, I do recommend it to the beginning 3D pilot. I don't consider myself a beginning 3D pilot after the long hours of bashing my 3DX around, but I'm far from being an expert. I've watched a lot of 3D videos on the E Zone as well and from these experiences I can definitley say that I wish I had started learning 3D with the Slipper II because of it's rock solid stability.
Foamwing has the Slipper II dialed in. All the bad habits of my first flate plate 3D foamy have been dealt with in the Slipper II. There's no wing rock, the depron cross piece down the fuselage eliminates tail twisting, and all the surfaces are aerodynamically balanced for instant control response. The price for the basic kit is a steal and the deluxe kit price is very reasonable for the builder who wants all the hardware supplied. I definitely recommend this plane to any 3D pilot.
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