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Old Mar 02, 2015, 01:04 PM
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FMS Fox Glider V2

My time prohibits doing a full review with pictures/videos, but here is a synopsis of my experience so far in building and flying, including over a dozen landings. I purchased the plane from www.MotionRC.com in order to do formation aerobatics with a friend who also got one (slow large graceful aerobatics to music). I am using an OrangeRX RX3S receiver/stabilizer due to windy conditions in our area. Spektrum DX-8 TX. I have built over 200 RC planes in the last 45 years. In my younger years participated in pattern contests.
=CONSTRUCTION=
+ Manual is pretty much worthless. Includes steps for a different plane, and omits required steps. Consequently, not a kit for newbies to building foam arfs/pnps.
+ Aileron hinges are weak and stiff. I ended up replacing hinges with real plastic hinges. Adding filament tape diagonally helped keep ailerons from warping during controls (and minimize exposure to flutter on high speed passes).
+ Kit was damaged in shipment. Both trailing edge bases/inserts on the wings were broken off. Glued and filament taped back on.
+ Stabilizer/elevator was 10-degrees out of parallel to the wings. Required 3mm shim to bring into alignment.
+ The RX3S requires pointing forward, and level with wings, and positioned near CG. Therefore I cut a square out of the rear seat canopy to mount the RX3S on the fuse near the leading edge of the wings. Routed server wires OVER the tunnel instead of thru (which also facilitates plugging/unplugging wings). RX position on top also allows easy access to stabilizer controls.
+ There is nothing to hold the wings on, and being the anal retentive person I am, I have 3-inch skewers poked at about a 10-degree angle from the cockpit down thru the fuse, the wing base, and the fuse, about 1-inch back from LE. I may replace these with magnets which would break free on a crash and not damage the fuse.
+ The spinner came off in-flight on about the 4th flight. Now held on with Scotch tape parallel to the spinner plate seam.
=FLYING=
+ The 40-amp included ESC “back fires” if throttle applied too rapidly. Exactly the same problem with the ESC on my Dynam SMART plane. Have to advance throttle slowly to keep ESC from wigging out and doing a sequence of “kick backs”. This is not a battery-at-cutoff issue. Extensive testing and measuring with watt meter and low battery meters, and using high capacity batteries, reveals the battery is not at cutoff voltage when the rotational prop jerking occurs. It is caused by the poorly engineered ESC’s getting “out of sync” with motor feedback. This is a particular nuisance on go-arounds (and probably the reason the spinner popped off).
+ Hand-launching is a non-event. Hold plane at rear edge of front wheel faring -- toss gently at about 70% power.
+ Keep elevator throws low – the plane is pitch sensitive which creates noticeable wing flexing.
+ There are several flight issues resulting from the plane being somewhat underpowered for an aerobatic plane. For more thrust I would upgrade to 4S batteries, but the motor will not handle it (the ESC supposedly will). The power is sufficient to use the plane as a thermal glider, where lightness is a plus. Good 1300mah batteries will last about 5 minutes if doing aerobatics. I’m considering up’ing to 1500 or 1600, but I already have an investment in 1300’s.
- Will not do an axial roll. Falls out of rolls if not at full throttle. However barrel rolls are nice and slow. I have a little mechanical differential in my ailerons.
- Will not do a large graceful loop. Runs out of energy/power on the upside, and ends up being a wing-over.
- Wingovers are short (height) due to rapid loss of energy on the up-line.
- Inverted flight requires more down than I like. I started with the CG at 45mm, but plan to move it back to 50mm as suggested on RCGROUPS.
+ Considerable wing flex if maneuvers not done “softly”.
+ The flaps really work on this plane (they are 1/3rd the wingspan)! Landing with no flaps will likely result in an over-shoot. Half-flaps make nice controlled smooth landings with straight run-out. Full flaps she really comes down. If you want to make a spot landing come in slow with half-flaps until about a foot off the runway, the put down full flaps. Not mentioned in the manual, but required to prevent pitch changes with flaps, are 10% down elevator mixed with half-flaps, and 20% down elevator mixed with full flaps. If you have a TX with timed flap movement, a 1 second delay works well.
+ Some of my flying was in 8mph winds (measured). There was a very noticeable change in bouncing around (and wing flex) with stabilizer on and off. After experimenting, I have the stabilizer pots set to 60%, which keeps the stabilizer from interfering with aerobatics, but creates nice flat/stable straight flight and landings in the wind. NOTE: The RX3S does not allow both flaps AND TX controlled on/off - must choose one or t'other). The rudder is also very effective on cross-wind landings (and required for coordinated turns due to the ailerons being so far out). But you always keep your left thumb on the left stick anyway – right?

Other than the idiosyncrasies mentioned above, the plane is a great flyer. While my expectations as an aerobatic plane were not met (mainly due to insufficient thrust at speed), it is a good utilitarian sport flyer that can be used for a variety of events like all-up/last-down, sport aerobatics, and thermal soaring. Like any glider or old-timer, do not try to fly this airplane too fast (don’t overpower it).

In summary, if there is to be a V3 version of this plane, I would recommend a little more thrust available at flight speed for up-maneuvers (larger flatter prop?), and a better ESC.

P.S. I have nothing but praise for Motion-RC’s support, wide product selection, and rapid shipping. )
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Last edited by royp; Mar 04, 2015 at 06:18 PM.
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Old Mar 19, 2015, 02:31 PM
royp is online now
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Hood River, OR
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Convert FMS Fox to Warmliner

How to make this plane from good to wonderful! Do ALL of these steps. Failure to do so may damage your equipment. See supplemental pictures. What you are doing is increasing the max power from 225 watts to 375 watts. Prop RPM increases from 7.5K to 10K

1. Use 4S 14.8 batteries of about 1600mah. Place all the way back.
2. Cut the prop down to 11” and rebalance.
3. Cut cooling holes in the spinner.
4. Make the air exit hole under the fuse larger.
5. Using a wattmeter, set your TX throttle upper limit so max amps don’t exceed 25. Failure to do this may burn out your motor and/or ESC. On my DX8 top is set to 70%.
6. Using the FMS ESC Manual, go into programming mode and change the “Timing Setup” to High (22-30*). This step required only if your ESC “back fires” under load.
7. Put filament/strapping tape lengthwise, top and bottom, both wings to stiffen the wings.
8. Add about 1-1.2 ounces lead to the tail cone to balance the plane at 50mm (not 40mm per the manual).

You now have a “warm-liner” that will fly straight up, do huge loops and wing-overs without losing energy, do high speed passes. Also will fly inverted hands-off.
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Old Apr 09, 2015, 12:18 PM
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United States, IN, St John
Joined Mar 2011
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Brand new plane but I have to modify 8 things for it to fly well....would you suggest the radian over this glider ?
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Old Apr 10, 2015, 01:57 PM
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Hood River, OR
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Choices

In that I have both planes in question, here is my opinion.

The Radian (non-Pro) is a good sailplane. It will do a loop, but being 3-channel it will not do aerobatics very well. It's not really a "sport" plane -- just lazy flying while sitting in a chair looking for thermals.

The Fox unmodified is more than just a sailplane. It is more of a "sport" plane. However it is underpowered for an aerobatic plane. Modified as suggested here, it is a great "sport" plane capable beautiful slow large scale aerobatics, and quasi-hotliner flying. It is also a good sailplane, though not as good a soarer as the Radian.

If I were in a soaring contest I would use the Radian. If I wanted to put on an air show (to music?), I would use the Fox. I get comments all the time about how beautiful it looks doing a large scale pattern routine.
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