A Different Kind of Review
Most of our E-Zone reviews come in one of two forms: either a manufacturer/vendor sends us something they want us to review for them, or someone writes up a review of a plane they purchased on their own simply for the fun of it and they submit it to us. In this case, my neighbor (John Little) purchased a Kyosho Cessna 180 ARF as a quick way to get into R/C flight. After some less than successful attempts at flying the Cessna and much frustration, he gave the plane to me. Upon observing how a few changes to the Cessna made it a very competent and sweet flying airplane, John purchased another one and offered to let me take photos for an article in return for helping him with the modifications. I've had so much fun with the Cessna that I took him up on the offer so that you can see two things: 1) A review of the Kyosho Cessna 180, and 2) How to take a marginal flyer and completely change its personality.
Kyosho has produced some remarkably successful electrics over the past few years (note how many T-33's and F-16's are now flying), but they seemed to take a step backwards with the Cessna 180. It's a very easy plane to assemble, it has a nice scale-like appearance, and it's very complete, but it's also a very marginal flyer in stock form with the recommended full-size equipment and 6 cells. There just isn't enough power. I think companies like Kyosho are trying to get people into electrics as cheaply and easily as possible (by using standard radio gear and R/C car battery packs) - a laudable goal - but in the process many will be frustrated and give up. That would be a shame in the case of the Kyosho Cessna 180. A few changes will transform this plane from nearly unflyable to one of the nicest flying planes I've laid my hands on.
As you can see in the kit contents photo, the Cessna 180 comes very complete, with very little work to do. Even the decals are already installed! All components are of good quality, and Kyosho has several novel approaches to things that I think are truly great ideas - such as their pushrod clevises and the battery retention system.
Construction (Using the Word Loosely!)
This is probably the hardest part of the kit - and it's pretty simple! Basically, you need to make sure the spar fits the wing notches properly, then epoxy it into place on one side. Once dry, epoxy the two wing halves together, being sure the spar fits flush (which assures you of the correct dihedral). A plastic plate covers the center of the wing, enhancing appearance and protecting the wing from damage by the rubber bands used for wing hold down. One change I made - which I very, very, very highly recommend - is to add a few full-length strips of fiberglass reinforced strapping tape to the bottom of the wing. The Cessna is quite capable of aerobatics with a decent motor system, but you'll snap the wing if you go too crazy and don't have the wing reinforced with strapping tape. John's brother found this out the hard way. I've put mine through all kinds of aerobatics without any problem using a taped wing.
There really isn't anything to do to the fuselage, other than install the landing gear and install and hook up the radio equipment (which I'll cover further down in the column). The landing gear simply requires that you screw a hold-down plate over the wire gear on the bottom of the fuselage, put the wheels on, and install the wheel collars. A plastic tail-skid protector needs to be epoxied over the tail skid under the rear of the fuselage.
The landing gear on the Cessna is held in place by an aluminum hold-down plate, which works quite well except that it will eventually fatigue if you land too hard too many times (any landing in which the gear is pulled back). I land on grass most of the time, and some of the fields are fairly clumpy, so the small wheels on the Cessna will tend to catch on the clumps and pull the wire gear out from under the plate. This is kind of a nice feature - rather than tearing up your airplane, the aluminum plate will bend out of the way and let the gear go. Eventually the bends on the side of the plate holding down the gear will give way permanently, so what do you do? In the photos above you can see what I did with my older, well-worn Cessna. I used some Nylon gear clamps, placing one on the back of the plate and trapping the other two under the plate further forward on the gear. It worked pretty well, except that the front Nylon pieces eventually got cut by the plate. After that I trapped a piece of wire over the gear and under the plate. It's still working quite well.
Here's the battery bay arrangement I like so well. Kyosho supplied the Cessna with the bay under the plane; the plate and Velcro fasteners are already installed. This way you don't have to remove the wing or open a hatch to change the battery, and the battery gets plenty of cooling air. You just turn the plane upside down, hook up the battery, and strap it to the plate.
Tail surfaces are pre-hinged, and the vertical fin is already in place (although you may want to pull it out of it's slot and epoxy it in if it's loose). You pretty much just need to epoxy the stabilizer to the fuselage. Pushrods are pushed through the foam at the pre-cut locations and connected to the servo arm with a Z-bend (already bent into the wire). The control surface end goes into a rather clever clevis. No need to cut, epoxy, bend, or solder here. Just insert the wire into the clevis and tighten up the set screws. It makes adjustment very easy! Control horns are installed by pushing the mounting screws through the foam and tightening them into a nut plate on the opposite side.
Radio gear installation doesn't get much easier than this. The Cessna 180 comes with pockets for the servos, receiver, etc. already formed in the fuselage. Just push your components in place! I used a Hitec Focus 3 transmitter and receiver in my Cessna, along with a couple of standard-size Airtronics servos. John used a Futaba 4-channel radio with standard servos in his Cessna. I initially used an AstroFlight geared 05 cobalt sport motor with a Master Airscrew 12x8 folding prop and a Castle Creations Pegasus 35 BEC speed control for my Cessna, but John was so impressed with the way it flew that he purchased the motor and speed control from me as soon as we started on his Cessna. I replaced those components with an AstroFlight geared cobalt 035 sport motor turning an APC 10x8 prop and an Astro Flight 217D speed control. Bob Boucher of AstroFlight recommended the 035 (which I think was a great choice, but more on that later). I initially intended to use the AstroFlight 215D BEC controller, but Bob didn't have any in stock at the moment, so he sent along a 217D. I opted to use a full 600 mAh receiver pack with this controller, just to see how the Cessna would react to the extra weight with the more powerful motors.
Power System Change
From the factory, Kyosho's Cessna 180 comes equipped with a Mabuchi 550SH motor and a 7x5 nylon prop. Recommended battery packs include 6 or 7 cell packs of 1500 mAh - 2000 mAh capacity. I tried to model this setup in E-Calc, but I don't think I got a perfect match. Both Mabuchi motors listed in E-Calc (a 550RS and a variant of the 550SH) seemed to have lower rpm/volt (Kv) ratings than I suspect this motor has, so I played around using the values from a couple of equivalent Graupner Speed 600 motors (the 7.2 and 8.4 volt versions). I think the 8.4V version made a fairly decent match, judging by what I've heard about the flying characteristics of the stock Cessna. I was originally intending to try it stock before making the modifications, but John wanted his "heated up" right from the beginning. According to E-calc, the 6-cell motor with a 7x5 prop and an 8.4v Speed 600 motor should turn the prop 9700 rpm while pulling about 14 amps and giving a 200 ft/min climb rate at 33 Watts/lb. (2.8 lb. airplane). This is probably about right; it's flyable, but you would need to be a fairly decent pilot and avoid over controlling or trying to climb too fast to keep it in the air. Upping the cell count to 7 or 8 helps matters quite a bit; 7 cells ups the power level to 44 Watts/lb. and the climb to 350 ft/min, while 8 cells improves things to 57 Watts/lb. and the climb rate to 480 ft/min.
A Little Math
How do you determine how much power you need/want? Dr. Keith Shaw proposed a formula some time ago based in input Watts/pound that will give a pretty good indication about how a plane should fly. As a rule, 30 Watts/lb. will sustain flight, 40 - 50 Watts/lb. will allow takeoffs from hard surfaces, 60 Watts/lb. will give you moderate aerobatics, 70 - 80 Watts/lb. will give you aggressive performance and good aerobatics. Above that will give you terrific performance. To determine your Watts/lb., you need to measure the voltage and current being supplied to the motor. Volts * Amps = Watts. Take that number and divide it by the weight of the plane in pounds. If the voltage is unknown, 1 Volt per cell usually makes a good approximation. Of course, actual performance will vary - more efficient motors will give higher performance at the same Watts/lb. rating (more input energy is converted to output energy), and a plane with a lighter wing loading will typically fly on less power than a plane with a higher wing loading. As you can see, the Cessna is a little marginal with the stock setup on 6 cells. The proposed substitution of AstroFlight cobalt motors on 7 - 8 cells changes all this; propped for approximately 30 amps, the Cessna now boasts 210 - 240 watts, yielding up to 80+ Watts/lb. (depending on cell count). In addition, the cobalt motors are typically 10 - 15 % more efficient than the ferrite motors we're replacing.
Here comes the fun part! These pictures show the steps required to breathe new life into the Cessna 180. The first step is to removed the prop and adapter, then the cowl. You'll have to cut the decal and unstick the tape to remove the cowl, but it comes off pretty nicely after that. I then cut the three tie-wraps holding the stock motor to the motor mount and removed the 550 motor. Since I'm running a geared motor (I originally flew the Cessna on an early direct-drive AstroFlight cobalt 05 using an 8x4 prop with good results as well), I removed the metal plate underneath the mount, turned it upside down, and placed it on top of the mounts. This mounted the motor a little lower to bring the gearbox shaft more inline with the cowl opening.
You're actually seeing two different motors in the photos; John bought my AstroFlight geared 05 off me for this airplane, because he was so pleased with the way it flew. When I called AstroFlight for a replacement, Bob Boucher recommended trying a geared 035 instead. My airplane features the 035, but I don't show much of my airplane because it has quite a bit more usage/wear (in other words, it's "uglied up" a bit). The 035 can be recognized in the photos by the open endbells (for better cooling) and by the newer gearbox, which is hexagonal and features a pair of mounting bolts aligned with the shaft. The 05 box is wider below the output shaft and tapers towards the shaft.
Mounting of either motor is the same, and equally simple: Place the motor under the mount and secure it with a hose clamp. You'll also want to make sure the motor is located far enough forward that the output shaft extends through the cowling. The cowl may have to be opened up a little around the shaft hole to allow the prop backplate on the shaft to clear. Now replace the cowl. I used some white plastic tape to secure the cowl to the fuselage. Depending on which prop you select, you may still be able to use the supplied spinner.
As an additional modification note, we changed all the connectors to Anderson PowerPoles (Litespeed and Sermos connectors are similar). I would strongly recommend changing to a high-quality connector like these or the AstroFlight ZeroLoss connectors. These high-quality connectors will keep resistance to a minimum, improving performance. Even with the stock motor, a change in connectors can prove beneficial.
Here's what the Cessna looks like when all is said and done. These pictures show John's airplane, with the AstroFlight geared 05 and Master Airscrew 12x8 folding prop. I believe he's running 7 1700's or 2000's. I'm using an APC 10x8 with my AstroFlight geared 035, running either 7 SR Max 2400's or 8 SR Max 1300's.
This is what it's all about. With an AstroFlight powerplant turning the prop, Kyosho's Cessna 180 becomes a whole new animal. Takeoff's are very short - on the order of 10 to 15 feet - followed by a strong climb. The Cessna will loop easily and successively from level flight. It's actually quite good at performing nice square loops. It will spin, but you'll have to hold full rudder and elevator through a turn or two to really get it wound up. Inverted flight is easy for the 180, although I still find it somewhat tricky to hold a rudder/elevator plane inverted for long, especially a high-wing plane like this one. Like most rudder/elevator planes, rolls aren't terribly great, but the Cessna has great responsiveness and it will really turn nicely. You can have great fun doing stall turns, pulling very tight circles, or buzzing the deck - there's a high confidence factor with the Cessna. Surprisingly, the Cessna 180 also has a pretty decent float/glide. It seems to really hang when you shut the power off. Above all, it just simply looks nice floating around, very much like the real thing. Landings are a non-event - just float it down and let it settle. John Little told me recently that his Cessna 180 was the most enjoyable of any of his planes (he's acquired several others since he first purchased the Cessna).
As a follow on to my comments about using the Astro 217D speed control with a 600 mAh receiver pack, I'll have to say I'm very impressed. My Cessna doesn't seem to notice the weight, and the controller functions flawlessly. The opto-isolation seems to work very well - I have yet to see any sign of glitching, which I have seen in one or two of my BEC controllers. I'm still a big fan of using BEC on planes like this one, but I won't complain about the performance of either the plane or the esc. Using a BEC controller (like the Astro 215D or the Castle Creations Pegasus 35, which I also use) just makes the plane that much nicer by saving the extra weight and removing the hassle of making sure the receiver pack is charged..
I'll have to second John Little's comment and say that the Kyosho Cessna 180 - with an AstroFlight motor - is one of the most enjoyable planes I own. It's become my regular "lunch time special", a plane that just simply fun to fly at almost any time. It's also one of the easiest planes to build that I've seen, and it will fly very well with standard radio equipment. I highly recommend this combination of the Kyosho Cessna 180 and an AstroFlight geared 035/05 for a great flying airplane with minimum time or expense. True, modifying Kyosho's plane with a cobalt motor isn't the cheapest way to get airborne, but if you want to have real success in electric power you need to invest in quality components. The rewards are well worth it!
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