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By Steven Horney - Email: Steve

Browse Articles by Steven Horney - Articles

Specifications:

* Wingspan: 59 in.
* Wing Area: 480 sq. in.
* Length: 42 in.
* Flying Weight: 53 ounces
* Wing Loading: 15.9 oz/sq. ft.
* Airfoil: flat bottom
* Motors used: 2 480-type motors
* Props: 2 Graupner Super Nylon 6x4
* Cells: 8 1900mAh
* Radio: Multiplex Cockpit, Hitec 555 receiver, 4 Hitec HS-81 servos
* Speed Control: Jeti 35 micro
* Manufacturer: Kavan
* Available from: Hobby Lobby International - Web site: Hobby-Lobby

Kavan took the current trend of easy-building, nice-flying foam models and upped the ante a notch with the Partenavia. Designed as a semi-scale version of the Italian P-68 Partenavia light twin, the Kavan model adds such nice touches as landing gear (including a steerable nose wheel) and a healthy power system (twin 480's) to make this twin stand apart from the crowd in both performance and appearance.

Kit Contents

Like many foam airplanes, the first thing that strikes you about the kit contents (at least for me) is that fact that this looks like an airplane already! It looks like you could just stick a few parts together, and voila! Off you'd fly! Of course, it isn't that easy, but it isn't all that far off, either. The foam parts of the Partenavia are made from a fairly smooth, higher-density white foam, so you don't get that rough, porous surface that many foam planes have. Some of the parts look a little light at first, but it feels quite solid once it's assembled. One other thing that stands out about this kit is that it's very complete, right down to the wheels and fittings. Some people like to select their own components, but I personally like a very complete kit so that I don't have to go shopping for all the little things that an airplane seems to need. Not shown in the photo above is the rather large, extensive decal set. Kavan uses large, vinyl decals to give the wing and tail surfaces additional strength. The decals also serve as hinges for the control surfaces.

The instruction manual with the Partenavia includes quite a few illustrations, and it's a good thing. The multi-lingual text is fairly minimal. Even with the illustrations, you have to be careful on several steps to really understand how things are assembled.

Construction

The following construction descriptions are not necessarily in order of assembly, but rather I've tried to arrange things by components.

Fuselage

Installation of wing bolt threaded bushings (left) and landing gear threaded bushings (right)

< < Receiver mount in place

The first step in the fuselage assembly involves epoxying a number of threaded bushings into the foam. Four bushings are used on top of the fuselage for the wing hold-down bolts, while another two are used on the bottom of the fuselage for landing gear mounting bolts. Few airplanes use more than two bolts or two bolts and a pin to hold the wing, but this is actually a pretty clever way to mount the wing - the wing bolt bushings are located in the sides of the fuselage, where the fuselage is the strongest, no bridging is needed to provide wing support, and the four bolts distribute the wing stresses over a greater area, reducing the loading on the bolts (or more importantly the bolt holes in the wing) and eliminating the need for more than a bushing to provide wing bolt support. Of course, this does mean you'll have to spend a little more time attaching and removing the wing! Also shown in the photos above is the receiver mounting tray, a plywood piece epoxied between the sides of the fuselage.

Landing Gear

Nosewheel assembly: the left photo shows the components, including my own piece of control rod sheathing for the collars. The middle photo shows the assembly, including the mounting block. On the right is a picture of the installed nosewheel assembly. In order to keep the wheel pant from rotating, I used a piece of white plastic tape across the wire and the wheel pant.

Main wheel assembly, shown in component form on the left and installed on the right.

Landing gear assembly was probably the most complex part of the Partenavia - mostly because the instructions leave something to be desired on this point. My best advice is to CAREFULLY look over the parts in the kit, compare with the parts list on the back of the instruction booklet, look carefully at the assembly instructions several times, and only proceed when you feel you understand how everything is assembled. My photos show the parts for each assembly, but I did make one modification to the nosewheel assembly. The instructions say to cut collars for the nosewheel assembly to get it to center properly. I couldn't find any material in the kit that looked like collar material, and none of the pushrod or antenna tubing fit, so I ended up finding a piece of pushrod sheathing that fit the axle properly and cutting a couple of collars off it. It worked perfectly.

Prior to assembling the nosewheel, the instructions tell you to make a hole for the nosewheel steering cable with a steel wire (brass tubing could be used here as well) and to epoxy the tube in place. Here's where I made a mistake in building (although it didn't cause me any problems). I ended up using the tube that should have been used for the antenna tube for this purpose, when I should have used some of the pushrod cable sheathing. The instructions show the tubing to be a separate item from the other sheathing, and the only "extra" tube I found turned out to be the antenna tube. This didn't really cause me any grief, since I just routed the antenna out the side of the fuselage and the cable works fine for the nosewheel, even with a little extra slop, but it's something to be aware of.

Most of the rest of the landing gear assembly went along pretty well. I did have to remount the wheels on the main gear when I got the gear on backwards. The instructions don't do a good job of showing which way the aluminum gear faces, and the slight difference in the front and rear of the gear will give the gear either a forward or a rearward rake, depending on how they are installed. Since the wheel pants are also directional, it isn't as easy as simply reversing direction. For the record, the gear should have a slight rearward rake.

Once all the landing gear is assembled to the plane, a foam block is to be glued in place over the main gear. I used white plastic tape to hold it instead, allowing me to remove the gear if I ever need (or want) to do so.

Once assembled, the landing gear on the Partenavia are wonderful - the plane seems to roll easily and with very little friction on hard surfaces. One or two high-bounce landings have also proven that this gear can take it. I was concerned that landing gear on a foam plane would rip right out at the first opportunity, but not so here - Once when landing in high winds a gust caught the plane and ballooned it up about three feet, then dropped it on it's gear. The result was a lightly bent nose gear wire, which I easily bent back into position.

Tail Surfaces

Assembling the tail surfaces on the Partenavia is almost a non-event. The horizontal stabilizer and elevator are one piece, with a groove molded in to define the leading edge of the elevator. The rudder and vertical fin are similar, except that this molding also includes a section of the top half of the fuselage. Control horns are fiberglass and are attached to the rudder and elevator with epoxy. The elevator horn goes into a slot in the elevator, while the rudder horn is bonded to the bottom of the rudder. Before bonding the control horn to the bottom of the rudder, the equivalent thickness of the horn must be removed from the bottom of the fin. Next, decals are applied to the tail surfaces. One large decal covers the top of the stabilizer/elevator, acting to both strengthen the parts and to serve as a hinge for the elevator. A large decal is likewise applied to both sides of the vertical fin, with one side serving as the hinge side.

The horizontal stab is now epoxied into place. Before the vertical fin/fuselage top assembly is epoxied into place, sheathing for the control cables must be fitted into the grooves and epoxied in place. The control surfaces are not cut free until the servos are installed and the pushrod cables are installed. This is a smart way to do things - accurate control setups are almost guaranteed.

Wing

The first step in the assembly of the Partenavia is epoxying the wing halves together, but while the instructions show you how to assemble it, they never mention gluing the center section! At any rate, it's pretty easy to figure out. One nice touch with this kit is the pre-installed bolt bushings in each wing half. I began the wing assembly by placing cardboard pieces at various points under the wing to keep it level (the nacelle top halves protrude below the bottom of the wing, making this necessary). After applying epoxy to the wing center and joining the two halves, I taped the sections together to make sure the wing halves stayed in proper alignment (and together!).

The pre-cut servo pockets fit the Hitec HS-81 servos perfectly - just a little compression to help keep them in place. You really don't even need to glue them in place, but it might be a good idea to do so anyway if you are concerned about how well they'll stay. I didn't glue my servos in, but I added a piece of strapping tape over the servos for extra security and a little drag reduction. The channels in the wings for the servo wires are really designed for a very long extension, but I had to make do with a couple of smaller (12 inch) extensions on each servo, requiring me to remove some extra foam in the channels for the extension connectors.

The biggest hassle of the whole wing was probably the application of the decals! Kavan uses a large, vinyl decal over the top of each wing half to give the wing strength, add coloration, and serve as a hinge for the ailerons. It's a fairly complex item to cut out of the decal sheet, but the biggest problem comes from keeping the decal from doubling back on itself. I ended up with a rough looking spot on the top of one wing when I was separating the decal from the decal sheet and I had the sheet roll back on me, causing the unwaxed paper back of the sheet to get stuck to the decal. I was able to remove most of it, but some of the paper became permanent. On the other half of the wing I employed a different strategy; I cut the paper backing off as I unrolled it, keeping it from curling back. After the decals are applied and the pushrods are installed, then the ailerons are cut free from the wing.

One other point that I consider quite important is the application of Nylon strapping tape to the bottom of the wing. The wiring for the aileron servos and the wiring for the motors is installed in the same wing slot, followed by a spruce spar. The spar is not full length, however, and I felt the wing had more flex than I was comfortable with. In order to be on the safe side, I added a couple of strips of the tape to the bottom of the wing, along the spar region. The decal on the top provides the extra bending strength for negative G forces. The wing still has a lot of flex, but I've put the Partenavia through a lot of aerobatic maneuvers (roll, loops, inverted flying, etc.) with no ill effects.

Motor Installation

The Partenavia uses a pair of Speed 480 motors for motivation. Although called 480's, these motors are more like a longer, more robust 400 in that they have the same 2.3 mm shaft diameter. The Partenavia motor package includes a pair of Gunther props, but I used a pair of Graupner 6x4 Super Nylon props included in the review package. The originally included prop adapters were for 3.2 mm shafts, so I ended up using a pair of Speed 400 Graupner spinner/adapters. These look better anyway - they're the items shown in the picture on the box. Also included in the motor package were some diodes, which I soldered on the back of the motors.

The speed control is a Jeti 35 microprocessor controller, used to power the two motors wired in parallel. As a side note, I used the solder Hobby Lobby included in the accessories package for all my soldering. It really seems to do the job well.

The first step of motor installation is soldering the wire to the motor terminals. The wires are then installed in the wiring channel running from the cowls, under the wing spar (wiring is installed before spar installation), and out through a hole in the bottom of the wing. At this point the wires are soldered together for a parallel setup (negative wires together, and positive wires together) and a connector is soldered on. I used the included wiring, but I used my own Anderson Power Pole connectors, since that's how all my batteries and chargers are currently equipped. Once everything is setup, the motors are epoxied to the cowls. You could epoxy the bottom of the cowl halves to the wing, but I used tape instead so that I can access the motors if I need to.

Final Assembly

Shown above are the HS-81 servos for the elevator and rudder. The HS-81's fit the servo pockets well, requiring only a little relief in the servo pockets for the wiring. The instructions say to epoxy the servos in place, but mine seemed to fit well enough that I omitted the glue. As it turned out, my nosewheel cable and my rudder cable didn't come out as close as I would have liked to their respective positions on the servo arm, but it worked out ok.

Hooks for the hatch are screwed into dowel pieces, which in turn are epoxied into the hatch and the fuselage(far left). Some photos of the final setup, showing the receiver, the rudder and elevator servos , and the 8-cell, 1900 mAh battery pack from Hobby Lobby International. Additional decals provided the finishing trim for the plane.

Final Product:

Below are some photos of the finished plane. Personally, I think this is one very sharp, even sexy looking airplane. Foam never looked so good!

Flight Performance

The Partenavia is truly a delight to fly. I've flown and reviewed quite a few planes, and nearly all of them have been enjoyable to fly if flown in the intended manner, but every so often something comes along that transcends more than one regime of flight and it becomes something very special indeed. The Kavan Partenavia is one of those planes; it's a plane that exhibits a sweet gentleness combined with a solid competence. Part of the fun is having a full-function airplane. Many of our e-powered planes are limited to hand launch and 3-channels. There's nothing wrong with that - those planes can be a lot of fun as well - but it's nice to have a plane with landing gear, a steerable nose wheel, ailerons, elevator, rudder, throttle, and (in my case) spoilerons, coupled with that neat sound that only a twin exhibits. The other side of the fun, however, is that the Partenavia exhibits trainer-smooth flight characteristics, including very scale looking takeoffs and landings, yet she'll loop, roll, and fly inverted about as easily as she'll fly straight and level. Power on or power off, I don't notice any pitching tendency. The Partenavia is also fairly efficient with the power - long flights are the norm with any reasonable throttle usage. Full throttle current draw is only 21 - 22 amps, and she'll maintain altitude somewhere in the 5 amp range. Using the 1900 mAh cells from Hobby lobby (114 Amp-minutes), 8- 10 minutes of fun flying is easily attainable. I've found that the Partenavia will handle winds pretty nicely. I've flown mine in winds up to 20 mph without problems. The tricycle landing gear really helps keep things rolling straight on takeoff's with high winds.

Low Speed Flight

Stalls - stalls are almost non-existent. Cutting the power and pulling full up yielded only gentle oscillations as the Partenavia pitched up, then settled back into level flight, pitched up lightly, settled again, etc. There was absolutely no tendency to drop a wing.

Takeoffs/Landings - the Partenavia tracks very nicely on takeoff and looks quite scale. I let her go about 40 feet then pulled back the stick and watched her climb away at about a 30 degree angle. I've been pleasantly surprised by the ability of the Partenavia to handle our club's grass field. As long as the grass length isn't excessive, I can take it off with either 7 or 8 cells. Landings are equally easy - the Partenavia has a pretty decent glide, and she settles in for easy, gentle landings. I've found it a little difficult to get bounce-free landings when the wind is strong, but it's easy to grease the landings on calmer days.

High Speed Flight

Loops - while the Partenavia is no F5B plane, she does have plenty of power for nice loops from level flight. With 8 cells you can get enough vertical to pull off pretty decent square loops.

Rolls - Rolls are nice and reasonably axial. Hold a little bit of down elevator as you go inverted and you'll be rewarded with a nice roll. I haven't tried point rolls or rolling circles, but they should be do-able with this plane.

Inverted - I found the Partenavia easy to fly inverted. Just roll her over and hold a fair amount of down elevator, at least with 8 cells. Inverted flying is marginal on 7 cells. Don't expect to do outside loops, as she doesn't have a lot of inverted climb, but she will hold altitude and climb gently inverted. Not bad, considering the flat bottomed airfoil. I would imagine that moving the CG a little further aft would increase the inverted performance, but I found it pretty reasonable as is.

Recommendations

I heartily recommend the Kavan Partenavia as a sweet-flying, scale-looking, just generally fun airplane. There are a few building quirks, but the rewards of flight are well worth it. I fly the Partenavia at every opportunity, and I never cease to enjoy it. It always seems to attract a fair amount of attention at the flying fields as well - not a bad thing!

To view the video go to: Partenavia

Electric videos: Video This article reprinted courtesy of the Ezone.

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