|Wing Area:||562.5 sq. in.|
|Weight:||8.34 lb (133.5oz) as tested|
|Wing Loading:||34.2 oz/sq. ft.|
|Servos:||Futaba Digital S-3151|
|Battery:||4.8V 1650 mah Nimh|
|ESC:||Hacker Master 77 amp|
|Flight Battery: Tanic Packs 5S3P 6660 mah Lipo|
|Available Online From:||Tower Hobbies|
The full size CAP580 belongs to Matt Chapman, a Great Planes sponsored pilot. Matt won the Silver and Bronze medals, and the Hilliard Trophy in the 1998 World Aerobatic Championships, held in Trencin, Slovakia. Matt was the highest-finishing U.S. pilot in the event, placing third for the Men's Team. During his career in aviation, Matt Chapman has worked as a flight instructor, charter pilot, air ambulance pilot, corporate pilot, and he is currently flying for American Airlines. Matt also flys RC model airplanes -- currently flying a 35% Carden Edge 540, a 35% Pitts 12, and a Top Gun-quality Ziroli P-51. He has competed in IMAC events several times and plans to attend more, along with any warbird fly-ins that his schedule allows.
The full-scale CAP 580 spans 24 feet, weighs just 1300 pounds, reaches 240 mph top speed and has a blisteringly fast roll rate of 400 degrees per second!
The 46-size ARF model is about 1/5 scale at 55.5 inches. The model required a 0.40 to 0.70 cu.in. glow engine for power. At the first full inspection of the kit, I was very impressed by the covering scheme of the model. It essentially reproduced the color scheme of the full size CAP 580 that Matt is flying, down to a sheet of scale decals. After removing all the pieces from the box, more kit details were revealed. The accessory pack was very complete - everything I needed to finish the kit was there, including a painted pilot, a painted cowl, wheels, wheel pants, a scale decal sheet and a special blue spinner that is color matched with the cowling. Also included was a very complete set of hardware, with all the linkages, control horns, rods, clevises needed for control system installation.
The assembly of the model involved sliding the parts into their designated places - that was it! The level of pre-work was incredible: the wheel pants had two blind nuts glued on the inside; hinge slots were precut; servo tray was installed; control rod housings were pre-installed in the fuselage, even the control rod exits were cut out already. Just about everything I needed was included - oddly enough, there was no fuel tubing in the kit - they must have known my kit was destined for e-conversion!
The instruction manual was very well laid out, with all the normal warranty and warnings printed in the front. Additional items required to finish the plane were listed in the manual. There was also a photo of the parts showing what should be in the box, and the contact information for Great Planes was listed, should there be any parts missing. The manual had step-by-step photos showing the assembly process, making the instructions clear and precise to the point that any modeler with average building skills should not have problem properly assembling this ARF.
The model was built-up construction using plywood and balsa wood - there was no foam in the wing. Servos locations were already cut out in the wing, also pull strings were installed so I didn't have to fish for the servo lead extensions.
I will not go through the step by step assembly process as the pdf version of the instruction is available on-line from Great Planes' web site. Instead, here are some highlights of the assembly process....
The only part that required pre-assembly was the plywood joiner for the two wing halves. Three pieces of the joiners needed to be glued together before fitting it into the wings, and I found that the joining of the two wing halves required a little sanding of the joiner to align the red and white "Bull's Eye" pattern on the underside of the wing. This "adjustment" was not critical to the structure of the plane but was more for aesthetics.
I needed to re-route the provided aileron servo wires pull string to the top of the wing before the two halves could be glued together, and in the end, I used one-hour epoxy to join the two wing halves together.
The hinge slots were pre-cut in all the control surfaces and their mating parts. The hinges used were the mylar type; the material came in a large sheet and I had to cut the required size hinge that I needed.
The kit manufacturer did most of the hard work in the factory. The wheel pants were painted and had two blind nuts(t-nuts) installed, so I was required to tighten only two screws to mount the wheel pants to the landing gear legs.
The landing gear mounting block and blind-nuts were installed in the fuselage, and the tail group alignment was perfect from the factory, no trimming needed! Taildragger main landing gear often need to have a few degrees of toe-in for ease in ground handling, so before the mounting screws were tightened,I pulled the wheels forward against the play between the hole and the mounting screws - this put enough toe-in in the landing gear. I used Loctite on all the machine screws.
Note: the landing gear bolt-on axle screws were not long enough to engage the nylon lock nut, so Loctite was used to secure the nut on the bolt-on axle.
Before the canopy could be installed, the pilot figure and the instrumentation decal needed to be installed. Warning: I had trouble trimming the canopy. The trim line is very accurate, but the paint on the pre-painted canopy started to lift as I was cutting the excess plastic off. So I had to be careful about the paint when trimming the canopy. A side note: in the Tech Notes on Tower Hobbies web page of the Chapman CAP 580, it stated "Canopy: Single clear, canopy is removable for easy access to radio equipment". This is incorrect for the 46 ARF version, the canopy is to be glued on and is not removable; the 1/3-scale version canopy tray IS removable. There was no access to the inside of the fuselage through the canopy. The cockpit floor was built-in permanently.
Futaba 9CAF-9C transmitter, Futaba R-148DF 8 Channel receiver and 4 x Futaba S3151 Digital servos control the Chapman CAP 580. The Actro 24-4 motor was controlled by a Hacker Master 77 amp Electronic Speed Controller.
The covering was very good, no loose corners or winkles throughout the plane. Attention to detail was great as every finger of the paint splashes had a drop of glue to keep the end from lifting. The only suggested improvement: the manufacturer should have provided a small piece of the base color covering to cover the gap at the base of the fin area. The cut out for the fin had square corners and the fin had a rounded leading edge.
I don't think I could find another plane that is more colorful than the Chapman CAP 580.
The electric conversion included replacing the glow engine with an electric motor -- an Actro 24-4 (kv=570), and a motor mount/extension. The instructions gave the distance from the firewall to the back of the propeller, which made it easier to calculate the length of the motor mount. For the power pack, I elected to use Lithium Poly cells to keep the weight down. After consulting with experts, a decision was made to use a 5S (18.50V) and capacity of about 6000-7000 mah. Tanic Packs offered a test pack of their new 2220mAh cells. Since I was not sure what battery configuration could be fitted to the airplane, I elected to request Tanic Packs to make three 5S packs so I could arrange the packs for best fit.
One major objective I have for any electric conversion is to make it easy to change the battery pack. I didn't want to turn the airplane upside down and remove the wing to get to the battery. As it turned out, the CAP 580 had an extension box in front of the fire wall. So the decision was made to put the battery in this box to keep most of the weight forward, as the Actro motor was lighter than a 0.70 4C motor. The extension box was cut and reinforced to accommodate the 5S3P Tanic Packs. The cowling also required a small part removed to clear the battery pack. The battery assembly was installed in place with two retaining screws.
The battery chosen for this conversion was a new cell from Tanic Pack, 2220 mah cell. Since I was not sure what battery configuration could be fitted to the airplane, I elected to request Tanic Packs to make three 5S packs so I could arrange the packs for best fit. The final form was a triangle shape (1 over 2), with a battery carrier to support the battery. The battery pack was secured with two screws, making the battery accessible from the outside of the plane without removing any part of the plane.
The Actro 24-4 turned a 15x7 Rev-Up propeller at 8100 rpm, drawing 55 Amps on the ground. The motor should run 7+ minutes at full power and 55 Amps. With a little power management and the propeller unloaded in the air, the flight should easily exceed 10 minutes. The time was confirmed later in flight tests that a single charge could fly two 6-minute flights without problem. The Hacker Master ESC was programed to have a cutoff voltage of 15Volts (3V per cell) to keep the LiPo battery from being over discharged.
The manual indicated the finished product would be 6.75 to 7.5 pounds, my finished electric powered plane weighed in at 133.5 ounces, or 8.34 pounds. With the given wing area, at 3.9 square foot, the wing loading translated to 34.2 oz/sq. ft. The Lithium Poly battery pack weighed 29.5 ounces compared to about 9 ounces for glow fuel in the provided fuel tank. A NiCad or NiMh battery of equal voltage (18 cells) and half of the capacity would have weighed about 40 ounces. I don't think this conversion would have been possible without the development Lithium Poly battery for hobby usage.
The Center of gravity was set about 1/8" in front of the recommended location after 2 oz of lead was attached in the tail. The control surfaces were set to factory recommended travels, Elevator: up 1/2", down 3/4", Rudder: Right /Left 3", Ailerons: Up & Down 5/8".
The model taxied without any tracking problem. The take off run was straight and no tail wagging was noticed. The model lifted off about 40 feet down the asphalt runway, leading into a good climb out. 3-4 clicks of up trim was needed to counter a slightly nose-heavy condition. The cross wind take offs were not a problem; once the speed increased, only a small amount of rudder was needed to keep it on the runway. The climb was good and strong, but not over powered at full throttle. Vertical maneuvers were not a problem, the plane was eager to go straight up from level flight for about 200 feet or so before slowing down. The CAP580 flew easily at 1/2 power to 3/4 power, only the most extreme vertical maneuvers required full power!
It passed the stall test, as it just slowed down and dropped it's nose. No bad habits were found on the stall test - I was happy with that! Standard aerobatics were easy and fun - snap rolls, inside and outside loops with level entry, spins - no problem for me or for the Cap! The model sustained inverted flight with less then 1/4 down stick, again being affected by the slight nose heavy condition.
Landing was easy but the plane should not be allowed to settle by itself - it needs to be flown all the way to touch down. At my CG, it dropped the nose as the speed was reduced for approach, so about 1/4 throttle was used to bring the model to a landing. It needed the slight thrust and air blowing over the tail surfaces for flaring, otherwise it would drop in making a hard touch down. Learning this during the first two landings cost me two broken propellers, but no other damage.
In subsequence flight tests, I increased the aileron travels to 7/8" up and down, although I retained the factory recommended setting in the low rate. The rolls were very fast, and it was on the edge of safe flying for me. I used the low rates for approach and landing.
I was asked to explore more advanced aerobatics or 3D-type flying, so we (I ‘volunteered’ a clubmate with competitive aerobatic experience to help) went back out to the field when the weather cleared after a few days. First, an analysis of the design clearly shows this model is not intended to perform 3D-style aerobatics, nor is it able to. I think it’s big brother (1/3-scale gasser) is more suited to that role, according to published information. This CAP 580 .40-size does not have the greater than 2:1 thrust-to-weight ratio required for 3D, and the specified control movements aren’t nearly enough for 3D, but we proved it can do everything else you can think of! A note here is in order regarding the maximum design horsepower for this model versus the power from the e-conversion: a .61 2-cycle or .70 4-cycle provides a maximum useful output of about 1.3 HP, and the e-conversion calculates to 1.2, resulting in calculated thrust of slightly more than the finished model weight; typical assumptions were used for propeller efficiency, pitch and useable RPM range.
In variable winds of 12-16 mph we gave the model a full ‘wringing out’ IMAC-style. Level flight trim was checked for neutral followed by dynamic checks, which revealed slight negative pitch coupling (down elevator) with large rudder angles. Having already explored the basic capabilities we concentrated on complex maneuvers and the availability of energy to accomplish them, mindful of the still slightly nose-heavy CG.
Without any assumptions we tried several advanced maneuvers such as Shark’s Tooth, Humpty Bump and Teardrop, concentrating on vertical lines to test climbing maneuver power (vertical snaps to various transitions) and downline speed control during snaps/rolls then to horizontal transitions. We kept knife edge maneuvers simple due to the pitch coupling and CG working against us, but showed the model climbs well in knife edge. Vertical power will run out eventually, but it is ample with normal power and speed management.
The airplane is not at all hard to fly, it does not require the pilot's attention at all time. Any pilots with aileron experience should not have a problem flying this plane. As I rated myself as a beginner pattern pilot, most IMAC maneuvers were not a problem. In the capable hands of an experienced pilot, in the IMAC competition, I think a trophy is within reach with this CAP580, as with the full size counter part.
The biggest virtue of this model is consistency of response over the maneuvering speed range, making it very easy to fly. The only negative response noted was a slight tendency to over-rotate during all types of snap rolls that was attributed to excess control input, something that should be mitigated with an aft CG correction; there were a few comments made about the gray-bearded pilot’s reaction time too, but they were ignored.
This is one of the most complete ARF kits ever, and the color scheme is really easy to see - don't be scared the first time you see the giant bullseye on the belly!
I'm surprised this conversion came in so heavy. Compare it to the Steven's Aeromodel Cap 40 kit that comes in under 4lbs AUW. Did you happen to weigh the parts before assembly? Very innovative battery solution. Have you tried a 15x8 APC prop? Looks like the Actro 24-4 would serve well in other glow 40 sized conversions. Are there any plans to post a video? Thanks for doing the conversion.
The motor is 13.5 oz(with my home made propeller extension adaptor), the motor mount is 2 oz. and the battery pack is around 30 oz. That is 45.5 oz from the 133.5 oz. and leave 88oz for the plane with servos, rx, battery. About the only thing I added is glue. I guest the plane itself is not light as it is not really designed as an electric plane. The firewall structure is very "strong" and well made, I did not have to add any support structure to hold the "fuel tank" in place.
I have not try the APC prop as yet. I was using the wood propeller to save the motor in case of prop strikes the ground on landing(which had happened).
I don't have a flight video, may be I can get one in a later date.
Thanks for your comments.
Brian, an EAJ
The power level is good for all around flying. The motor can handle more and will try to play with more propeller. I started with 14x7 and ran out of propeller(only have two of them) and went to 15x7. Initially, I want to use a three blade propeller, like the Graupner 14x7 wich I use on a AXI4120 and with greatr result. A lot of thrust and not too fast, but I can find a thre blade spinner in time for the review.
Brian, an EAJ
I suspect the weight givin on box for plane with glow version is another of those stretched claims
It would be interesting to know what weight the plane is with a typical 4 stroke 70 with a full tank
I suspect the result would be very similar in that the 4 stroke version would also be outside the stated weights
well done reasonably economic not F5b climb 3d hover overpowered with 55 inch props that seem to be the rage recently
According to spec, an OS 70-4C is about 19 oz.( 17-23 oz) The supplied fuel tank is 9 oz(plus the weight of the tank itself). The Actro 24-4 is 13 oz. and The battery pack is 30 oz. The coversion added about 10-12 oz to the plane.
Yes, Ralf, I am glad to see they do made a plane that does not meant to do hover.
Brian, an EAJ
Looking for a CAP 580 kit
Yes, I know that GP has discontinued the CAP 580, but we have been flying ours for quite some time and were very fond of it, until it found a tree the other day.
I know we should just scavenge the parts and move on, but we would really rather have a replacement ARF CAP 580 kit (we at least need the wing assembly).
Can anyone out there help?
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