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Introduction
The RV-8 is one of several designs by Richard VanGrunsven, founder of Vans Aircraft. Founded in 1973, Van's Aircraft is a homebuilt aircraft kit manufacturer. Van's RV series of aircraft, from the single seat RV-3 to the latest RV-12, are all-aluminum, low-wing monoplanes of monocoque construction. All, except the RV-3, RV-4 and RV-10 are available in both tricycle and tail dragger configurations. Append an "A" to to the RV-8 and you have the tricycle gear variant. The RV-8 was designed as an improved RV-4. Notable features include the ability to accept larger, more powerful engines, increased wingspan and wing area and more room in the cockpit to accommodate larger pilots. With a top speed of 222 MPH at sea level, a service ceiling of 22,500 feet and a range of around 780 miles, the RV-8 is even rated to +6/-3G for aerobatics.
With a wingspan of 5', the Hangar 9 rendition of the RV-8 qualifies as a 20% scale model of the full size aircraft. (Wing span = 24') While a RV-8 kit from Vans will require a little over $20K to purchase and 1600-1800 hours of build time, the Hangar 9 ARF costs about 1% of Vans kit price and comes out of the box with many of the normal building steps already completed at the factory. Total build time could be as little as 10-15 hours.
Kit Contents
Notable features include:
In The Box
The RV-8 ARF comes in a large, colorfully illustrated box. The contents are packed well, and Hangar 9 goes to lengths to insure that no damage occurs. The pre-installed control horns, which could easily end up being the cause of puncture wounds in the covering, are all sheathed in a thick tube of soft white foam. I like that all of the smaller parts, hardware and fasteners come segregated in several clear plastic bags that are labeled according to their contents. This is a great way to avoid the head scratching and confusion that can occur when all of the hardware is packaged in one solitary bag.
Required for Completion
Included for Review
Assembly
Hangar 9 makes the assembly instructions available online in an electronic format:
The black and white photo-illustrated instructions are complete and include several cutout templates that can be used during assembly. One is used to cut a hole in the belly of the fuselage that is necessary to provide an exit path for the all important cooling air. Another nice inclusion in the manual is a very complete list of the parts and hardware included in the kit, right down to the smallest nut and bolt.
Wing
The wing is a two piece assembly joined with an anodized aluminum tubular spar. Once installed, the halves are retained with a single socket head cap screw each. The wing halves come configured for both flaps and ailerons. All four wing servos get installed in the same fashion. I took the liberty of installing short screws into the servo hardwood mounting blocks. Though these blocks are epoxied to the plywood flap and aileron mounting plates, I like the added peace of mind offered by a secondary system of attachment for these critical control surface servo mounts.
The control horns are all pre-installed on this ARF. The flaps and ailerons are all pre-hinged as well which really speeds the build along. Once the four wing servos are mounted, all that remains is to pull the servo leads through the wing halves to the wing root. Pull strings are provided. Six inch servo extensions are required on the two aileron servos, which are located on the outer section of the trailing edge. The two flap servo leads will easily reach the receiver, with no extensions required. The wing halves can be installed or removed from the fuselage in seconds, making for easy transport to the flying field.
Fuselage
The fuselage of the RV-8 is quite wide and roomy inside. Removing the battery hatch exposes the entire forward top half of the fuselage. This hatch has two small dowels that index into one of the front fuselage formers, with the back of the hatch being held in place with a pair of magnets. Since magnets often fail to securely hold a battery hatch/canopy of this size, Hangar 9 also provides a pair of tabs with blind nuts pre-installed, into which 3mm socket head cap screws can be threaded. While this secondary fastening system adds a little extra time to a battery change, it guarantees that the hatch will not come off in flight.
One of the first steps of the fuselage assembly is attaching the two aluminum landing gear legs to the bottom of the fuselage. While attempting to thread one of the 3mm socket head cap screws into the pre-installed landing gear blind nuts, it became apparent that epoxy had somehow found its way into one of the blind nuts. The cap screw was so tight in the blind nuts threads that the blind nut popped up and out of the plywood landing mount. Once I had it in hand, I carefully threaded one of the 3mm bolts in and out several times while holding the blind nut in a pair of vise grips, until most of the epoxy was cleaned out.
The assembly instructions detail the need to align the wheel pants with the fuselage and then drill a hole for the wheel pant mounting screw. I was pleasantly surprised to see this hole already drilled. When inserting the 3mm blind nut for this fastener, it is important to note that it has a flat ground into one side of it. This flat needs to be positioned towards the wheel axle. The instructions recommend using a bit of CA to hold this blind nut in position on the inside of the wheel pants but I was a little hesitant to use CA near the wheel axles, lest it accidentally find its way onto them. I instead drew it down into the wooden plate inside the wheel pant by threading a fastener into it and tightening it down. Though the blind nut will only be partially drawn down, it is enough to hold it until final assembly of the wheel pants pull it the rest of the way down.
Do not forget to use thread lock on all of the metallic fasteners used on the landing gear.
Tail
The first thing most will notice about the vertical stabilizer is its snappy red and white checkerboard Ultracote finish. It looks great! The vertical stabilizer comes out of the box as an integral part of the fuselage. The rudder is already hinged and attached with a pair of control horns installed in preparation for the included pull-pull rudder setup. The horizontal stabilizers and elevators, also factory hinged and horned, will need to be epoxied to the fuselage. They are a brilliant Flame Red color of Ultracote and feature a pair of anodized aluminum spars for superior strength and rigidity. Hangar 9 includes a sturdy tail wheel assembly, and they save the builder precious time by mounting it at the factory.
I was dismayed to find one of the pull-pull rudder tubes had a blockage at its rear most point. Try as I might, I was not able to push the wire, or for that matter even a solid push rod, all the way through this tube. Though I at first thought this was going to be a major problem, the fix was to grab a spare tube of nearly equal diameter and run it in parallel to the jammed one. Once engineered, the solution took mere minutes to implement. In the photo below, the two smaller tubes to the right are for the rudder cables, while the two larger tubes to the left are for the twin elevator push rods.
Making up the rudder cables is easy and I really like the type of crimp ferrules that Hangar 9 includes in the box. I especially was glad to see they even include a few extra crimp ferrules.
The factory applied Ultracote covering seals over the end of the rudder and elevator guide tubes. To locate the exit points beneath the covering, you simply feed the cable or push rod into the tube and poke it back and forth a few times until you see the dimple forming below the covering. A sharp hobby knife can then be used to cut a small exit slot.
The two horizontal stabilizer halves are used as a guide to mark the covering to be cut out on the fuselage. I used five minute epoxy to attach the two halves, with plenty of paper towels and rubbing alcohol on the ready for wiping off the excess epoxy that squeezes out of the joints before it dries.
Power System Installation
Hangar 9 provides everything necessary to go with either a nitro power system or a electric one. Though the instructions mention using the provided motor drilling template located on the back of the assembly manual, Hangar 9 went one better than a paper template and provided an additional one made out of lite ply. It has the bolt mounting patterns for three different specific power systems: a E-flite Power 46 brushless outrunner, a Saito.82 four stroke and a Evolution .46 two stroke. Any of these three will bolt right up to the ply motor box with the included hardware in the box. Additionally, for those who elect to go with a glow based power system, Hangar 9 has already sealed the firewall and motor box against attack from fuel.
To use the included motor template, simply tape it to the firewall and drill the appropriate four holes.
In addition, when going with an electric power system, Hangar 9 recommends using a sharp hobby knife to finish cutting through the reinforcing panels on the top, bottom and two sides of the motor box. This is to facilitate the entry of that all important cooling airflow to the electric power system components. A paper template, provided on the last page of the assembly manual, is used to cut an exit hole for cooling air flow in the bottom of the fuselage just aft of the trailing edge of the wing.
The aluminum standoffs provided in the kit for mounting the E-flite Power 46 to the firewall are quite robust. It is necessary to drill slightly larger holes in the x-mount included with the Power 46, so that its four mounting holes line up with the aluminum standoffs. It is very important to use thread locker on the 12 fasteners used to anchor the Power 46 to the nose of the RV-8. The 60 amp E-flite ESC simply mounts to the side of the motor box with some hook and loop fastener material. You will need a 12" servo extension to reach the AR7000 receiver located further aft in the fuselage. I removed the On/Off slider switch from my speed controller. A mounting hole is provided in the fuselage, should you prefer to use one.
Radio Installation
The factory recommended radio components for the Hangar 9 RV-8 are JR DS821 Digital Sport servos (six for the electric powered variant and seven for glow) and a minimum of a six channel radio system. A well proven Spektrum AR7000 seven channel receiver was included for the review project. Four of the servos are mounted in the wing, while the final two get mounted in the fuselage. The JR servos dropped right into the cutouts on the fuselage servo tray with nary a need to enlarge the opening at all. Their 72 ounces of torque at 4.8 volts are sure to be more than plenty for the RV-8, which is at heart a true sport scale plane.
When selecting the mounting location for the AR7000, the cavernous fuselage of the RV-8 may fool you into thinking that you have many different locations that will work. However, it is best to locate it near to where the flaps and ailerons servo leads enter the fuselage. The satellite receiver should always go in a different orientation than the main receiver, in order to provide the best variations in communications paths. I placed mine forward and on the inside edge of the fuselage near where the leading edge of the wing will set. Though I simply hot glued the satellite in place, I created a small balsa shelf for the main receiver and CA'd it to the fuselage interior structure. With a few drops of hot glue I then anchored the AR7000 in place.
I really like using large pieces of heat shrink tubing to secure all of my servo extensions. The flaps servos are inboard and do not require an extension to reach the receiver when it is located correctly. The ailerons do require a servo extension, as they are outboard on the wings. I used a Y-cable to join the aileron servos together, while the flaps each received their own channel on the AR7000. A custom mix was used on the transmitter to set them up and I also added a little down elevator mix in on both of the flaps settings.
Completion
In around 14 hours of total building time, I found myself putting the finishing touches on the Hangar 9 RV-8. Thanks to its pre-hinged control surfaces and pre-installed control horns, the build speeds right along. The finishing touches included using my rotary power tool to cut the appropriate cooling holes in the fiberglass cowl, setting up the control surface throws as recommended in the assembly manual, procuring a pilot for the cockpit and canopy and checking to make sure the center of gravity is correct. Though canopy glue or smalls crews are typically used to attach the canopy, I elected to instead use two lengths of Blenderm surgical tape to secure mine. I hot glued my pilot in place. The cowl does not overlap the fuselage as is often the case but it instead attaches flush to the forward fuselage and maintains its pleasing lines and contours. The four pre-drilled holes aligned perfectly with the four mounting tabs in the fuselage. The color and covering scheme of the Hangar9 RV-8 is simple but with a touch of snazz and snap, thanks to its red and white checkerboard vertical stab and rudder and coordinating fuselage stripes. The stripes aligned perfectly as they transitioned onto the fiberglass cowl. When placing the canopy in position, a pair of aligning dowels index into a fuselage former at the front, while a pair of magnets lock the rear into place. For additional canopy retention security, a pair of small screws thread into blind nuts situated on tabs below the canopy deck on the sides of the fuselage. I personally found the gap between the rear of the canopy and the fuselage a bit excessive.
With all of the recommended electric power system and radio system in place and the Thunder Power Pro-Lite 4S 3850 lipoly battery strapped securely to the battery tray with hook and loop, it was time to check the CG and run the RV-8 across the hangar scales for an All-Up-Weight check.
With my RV-8 showing itself a bit on the tail heavy side, I decided to move the battery forward a little on the tray. However, due to the void in the fuselage interior structure reserved for a fuel tank when going with a nitro power system, the battery tray does not extend forward to the rear of the firewall. Needing to shift the battery forward to assist in moving the CG to the correct range, I constructed a small battery tray extender of lite play and attached it to the front of the existing tray and the firewall, using a piece of hardwood stick to create a ledge on the rear of the firewall for the tray extender to lay upon. With the battery all the way tight against the firewall, I decided to add one additional ounce of weight to the firewall, just to be 100% sure my RV-8 was a little nose heavy for its maiden flights.
The beautiful Hangar 9 RV-8 looks right at home on the ramp of a real airport, with a Cirrus and a Bonanza making for a nice general aviation backdrop.
Lets FLY!!
Flying
Basics
Hangar 9 recommends either a 13x6.5 or 14x7 APC E prop for the RV-8. I always like to take a peek at the total power being produced by my power system before I send an airplane skyward for the first time. My Eagle Tree data logger has a real time mode, with a LCD power panel that will report the numbers while doing a run up on the ground. I was a little surprised to see the 13x6.5 prop produce a mere 500 watts or so, while the larger and steeper pitch of the 14x7 raised this to around 700 watts. Running the numbers through my head quickly told me that the RV-8 would have only 100 watts per pound or so of available power. Now, due to the readily available and relatively affordable electric power systems technology, it is all to easy to routinely over power electric aircraft. Did I just think "only" 100 watts per pound?! I did a reality check and reminded myself that this is a sport scale aircraft, not a high performance 3D plane or EDF, and that 100 watts per pound should be plenty of power! My maiden and several subsequent flights were flown at a full size airfield, with a 2500x40' asphalt runway available for use. Excited as I was to get the RV-8 up in the air, I always like to make one final control surface verification check, as well as taking a few moments to go over the entire aircraft to verify that no small detail has been overlooked. Studying the lines and overall design of the RV-8 as a part of the preflight, I reminded myself that it is a somewhat short coupled airframe and that it could be a little sensitive in the pitch axis. The control surface throws seemed conservative compared to the variety of planes currently flying in my hangar but I always like to start with the recommended throws. Flipping my rates switch to high on elevator and ailerons, I took a deep breath and rolled the RV-8 out onto the taxi way.
Taking Off and Landing
Leaving the rudder on low rates, the RV-8 will track nicely on the ground but make sure you do not set more than 5-10% exponential or you may find yourself zigging and zagging down the taxi way. Using the recommended rudder throws, I did find it necessary to occasionally switch to high rates to tighten up a turn or two on the ground. Though the stance of the gear is fairly wide and the landing gear legs are very stiff, I noticed a very slight bounce to the airframe as it slowly rolled down the asphalt. I normally hold full up elevator while taxing a tail dragger but the tail of the RV-8 felt confidently planted with even minimal up elevator fed in.
When ready to start the take of roll, it is necessary to give quite a bit of throttle stick to get the RV-8 rolling down the center line of the runway. I did need to stay alert on the application of rudder but it was not difficult at all to hold the nose steady on the center stripe. As the speed builds, the tail will naturally come up off the ground. When the time is right, a small amount of up elevator will make the RV-8 rotate and lift off in a very scale like fashion. Though all of us like to perform the Wide-Open-Throttle with an immediate transition into a Rocketship-style take off and climbout, the RV-8 is NOT that kind of plane! After several flights, I found myself really enjoying the challenge of "making it look real' and working to keep the takeoffs as scale looking as possible.
Bringing the RV-8 back down is a little more demanding than the departure but then isn't that always the case? My initial landings were made with the flaps fully retracted. I usually like to see what it takes to bring an airframe in sans flaps and then go from there. The RV-8 looks very cool transitioning through the landing pattern and on final, I found myself a little high and fast. I resisted the urge to feed a lot of power back in and instead kept it flying on the wing, with only a little more power feathered in to hold altitude on my trip back around the pattern. On final this time, the RV-8 was much more willing to drop her nose and come down the glide slope. As expected, the pitch axis is a little on the sensitive side due to the short tail moment of the RV-8 but setting up the elevator throws as laid out in the manual will keep it tame and completely manageable. Most of my landings result in the RV-8 settling in on the mains, with no sign of the tail dropping until most of the speed is scrubbed.
Flaps
Using the flaps on the RV-8 opens up another entire dimension of flying! Whenever I have an airframe equipped with flaps, I always like to install servo rate reducers. Their value cannot be overstated when it comes to the way they prevent the airframe from being upset during the transition into and out of flap deployment. My transmitter does not have a way of slowing the flap servos, as many higher end transmitters are capable of doing. I simply use some inexpensive, inline electronic rate reducers. Takeoffs with either half flaps or full flaps deployed on the RV-8 are at a much slower airspeed than with the flaps fully up. I really like cruising around the pattern with the flaps down. The look of the RV-8 coming down final with the flaps dropped and visible at the trailing edge of the wing is awesome! The flaps also slow the landing speed of the RV-8 but the airframe is still very well behaved through the entire landing sequence. I cannot overstate how much fun it is to enter the landing pattern with the RV-8 and then work through the pattern just as one would in a real plane. It is especially cool doing it at a full size airstrip like I am privileged to fly at occasionally.
Aerobatics/Special Flight Performance
The real RV-8 is stressed to handle +6/-3Gs and in like fashion, this model of the RV-8 is also perfectly capable of basic aerobatics. The best part about it is it looks very scale as it performs them! With the ailerons, elevator and rudder all set on high rates, the RV-8 is capable of very cool looking aerobatics, including rolls, loops, and other basic moves. Rolls are slow enough that it is best to feed in a little down elevator during the inverted phase. Loops are not unlimited in size but modest sized circles can be cut with good energy management and planning. The longer I directed the RV-8 around the blue California skies, the more aware I became of how scale looking the Hangar 9 RV-8 looks in flight. The recommended power system does a great job of keeping the speed down, which is the first and most important step in keeping it real. Modest control throws also contribute towards keeping the RV-8 on the more docile and yet still exhilarating side of the performance curve. In the data graphs below, it becomes apparent that the RV-8 is very satisfied cruising around the skies with the throttle stick set in the middle of its throw. With the throttle set as such, the Power 46 sips the juice out of the Thunder Power Pro-Lite V2 4S 3900 mAh lipoly battery. The roughly four minute flight graphed below used only 850-900 mAh out of the battery. Even with a more typical and varied use of the throttle, flight durations of 6-8 minutes are attainable. Push the throttle to the stop however and the Power 46 will respond with a blast of power that can pull the RV-8 into a temporary vertical climb or set up nice fast passes on the deck at a pleasing clip. The video located a few pages below gives one a very good idea of the versatile flight envelope possible with the Hangar 9 RV-8.
Is This For a Beginner?
The Hangar 9 RV-8 is not a beginner’s plane but I would rate it as one that most intermediate pilots should enjoy. There is not an superabundance of power available, as many may have come to expect with their electric aircraft. Though the modest control throws require that you stay a little ahead of the plane at all times, the RV-8 does not have a nasty piece of balsa in its body, at least not that I have seen. It is very well behaved when set up as recommended in the assembly instructions. The fact that it is a tail dragger can also overwhelm beginning pilots who are most generally acclimated to tricycle gear aircraft and their commensurately easier ground handling.
Flight Video/Photo Gallery
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