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Precision Aerobatics Ultimate AMR Biplane
Very fast, very slow and great handling everywhere between
Text, photos and video by Tom Hintz
Posted – 7-23-2013
Shortly after I maidened my Precision Aerobatics Addiction X an apparent radio failure claimed my electric YAK with a full-throttle, full right aileron and full rudder plunge into the ground. Everything was junk (really, everything) so after a respectable period of mourning (9 hours seemed right) I ordered my Precision Aerobatics Ultimate AMR Biplane and my world just felt right again.
The AMR part of the name is not a reference to something aeronautical but rather a friend of the Precision Aerobatics folks who was stricken with cancer. The Ultimate AMR is a tribute to him. I suspect that Ultimate AMR will put a smile on the face of all who fly it which makes this tribute even more remarkable.
The Ultimate AMR has a 40 inch (1014mm) wing span with a wing area of 582.4-sq in. The overall length of just over 43-inches (1095mm) makes the Ultimate AMR easy to transport in smaller cars with the wings attached. It has a ready to fly weight (including battery) of only 38-1/2-oz (1089gr) which works out to an impressive wing loading of just 9.5-oz per square foot!
The remarkable lack of weight is made possible by the Precision Aerobatics FiberFusion® construction method that combines laser and CNC-cut carbon fiber, balsa and super light ply to create an engineered airframe that is as strong as it is light. The first time you pick the Ultimate AMR up it feels like something big fell off and stayed on the table. It is VERY light in the hand and in the air.
The Ultimate AMR reviewed here uses the Precision Aerobatics “Pro” package that includes a stout power system built around a Precision Aerobatics Thrust® 40 outrunner motor with RotorKool® technology, a Quantum 45A high performance programmable ESC, a German made CNC machined precision prop adapter, a Precision Aerobatics V2 Lipo 2,200mAh 11.1V 20-40c V2 battery pack and a VOX 14X7 (or 13X6.5) wooden prop. This is very similar to the power package I have in my Precision Aerobatics Addiction X so I expected big things when I gassed the markedly smaller Ultimate AMR.
This Pro package also includes 4 Nexatec NXT 80 DSM Micro servos each with a stall torque of 4.1kg/cm, 56.94 oz/in to make sure the large control surfaces react quickly to your commands. These digital servos feature metal gears, dual ball bearings and a heat sink!
I also found approximately 4 ft. of thin gauge twisted light extension lead cable that was used to solder into the servo leads to eliminate servo extensions. This eliminates additional connections that could fail while minimizing RF noises within the Ultimate AMR. We also get a set of 4 Carbon Fiber extended servo arms that help the overall servo/control geometry while adding flex-free strength to what are too often spongy plastic servo arms.
If you are not familiar with ARF kits from Precision Aerobatics the completeness of the Ultimate AMR will be surprising. They make extensive use of laser and CNC cut parts and then assemble all of the major components (fuselage, wings, tail and control surfaces) in high end jigs that insure straight true pieces every time. They even install the ailerons and elevator and seal those hinge lines all at the factory! Even the critical engine mount and support system is factory built to insure ending up with a proper flying plane. We do have to epoxy this engine structure to the rest of the fuselage but laser cut mounting surfaces make it all but impossible to get the angles wrong.
They also cover and decorate everything for you. That removes another time-consuming task and once again makes sure you come away with an attractive plane that flies as good as it looks. The use of transparent colors reveals the structure beneath for a very nice “engineered” appearance.
Making the assembly process easier is the complete, well-written and nicely illustrated instruction manual. Far too many of today’s products are cheapened by terrible instructions and the folks at Precision Aerobatics seem motivated to prevent that mistake with their products. The manual also includes a discussion on the placement of the CG (center of gravity) that gives you options and explains why they are there. Nice touch!
The accuracy of the cutting processes used to produce the Ultimate AMR become evident when installing components such as the servos. The openings tend to run slightly undersize but close enough that you only need a sharp hobby knife or small file to tweak them for a perfect, solid mounting. I have yet to come across anything in a Precision Aerobatics kit that was tough to fit.
The only place I varied from the Ultimate AMR instructions was in the control linkages. They provide carbon fiber components with which you make up very solid, super-light linkages. To be sure, these supplied linkages when made as described in the instructions are stout. I however am hopelessly old school and actually like perfecting the handling of a plane by making tweaks to the control linkage lengths. So I made up my own ball-end style linkages to afford me the adjusting capability while removing all free play from the system. Remember, this is my old school stubbornness, not a necessity.
In the Air
As is to be expected of a biplane, the Ultimate AMR is a bit more “hyper” in the sky than my Precision Aerobatics Addiction X but it remains very easy to fly. I maidened my Ultimate AMR on a blustery, gusty day and got in two flights before discretion overruled valor and I ended flying for the day. I was able to discover that the Ultimate AMR appeared to be close to trim and had plenty of power to zoom through the gusts with ease. It also lands better than expected which in the gusty conditions let me (foolish I know) do a few touch and go’s without incident or damage.
On a more reasonable wind day the Ultimate AMR was a joy to fly. It is still quicker than an aircraft like the Precision Aerobatics Addiction X in all respects but that gives you a wider flight envelope. It is capable of surprisingly slow-speed 3D maneuvers but can pull its way through pattern-type traces in the sky with ease. There is plenty of power to punch out of a failed 3D trick and live to try it again. The only direction I would fear applying full power to the Ultimate AMR is down.
The period between completing the build and finishing this review has been plagued with rain and wind so actual flying time has been minimal. I have been able to get the Ultimate AMR out a few times and each time it flies better than the last and is more impressive.
In the flying I have been able to do the Ultimate AMR shows no bad habits or shortcomings. I set the CG at 59mm which is just a touch forward of their sweet spot. Other than needing a bit of down trim - which nearly all biplanes need – the Ultimate AMR has flown great right off the bench.
The Ultimate AMR is a nicely sized biplane with the power and handling to keep the interest of even advanced pilots. However it can be docile as needed for 3D pilots in training. As is their habit the Precision Aerobatics Ultimate AMR uses super lightweight yet rugged construction to produce an airframe with capabilities of much larger planes along with the predictable handling.
The Ultimate AMR itself sells for $235.00 (7-12-2013) and the Ultimate AMR iPAs Pro package used for this review will set you back $539.95 but I think you get a lot for the money. If you already have compatible servos and the other electronic components you can put your Ultimate AMR in the sky for less.
If you want to add a great looking, great flying biplane to your electric hangar check out the Ultimate AMR. If this is your first Precision Aerobatics plane get ready to be impressed, now and later.
Accidental Stress Test
I would love to have ended this review on the high note it deserves but we all know that RC flying can be frustrating, in this case because I did something dumb. While making an inverted pass down our runway about 12-feet up I tried a rudder correction and went the wrong way, which I knew might happen. The Ultimate AMR twitched appropriately and dropped the nose a tad. At this point my 25-year-long layoff from RC flying manifested itself in dumb thumbs.
I instinctively went to full throttle (fine) but for some reason I jerked up elevator (definitely NOT fine) and the Ultimate AMR dutifully tried to do a 180 reversal. While the Ultimate AMR responded instantly the sickening “thud” signaled that it needed about 12.5-feet of altitude to complete the maneuver, about half a foot more than I had. The Ultimate AMR impacted the ground “on its chin” which snapped the prop and prop adapter off, knocked the landing gear out of the fuse and that led to some serious destruction of the surrounding airframe.
I do have to say that despite the impact the damage was confined to the fuse and motor mount areas. The wings are both fine and the electronics all survived, including the motor. All those lightweight pieces breaking up apparently absorbed the forces and limited the damage to the fuse ahead of the bottom wing.
So, this one is all on me. The Ultimate AMR did everything I told it to which unfortunately was dumb. It also survived the crash way better than I thought it would. I ordered a new airframe kit as it is cheaper than all of the pieces I needed to rebuild. I will fly it again and will give myself more time to educate the thumbs before bringing experiments so close to the ground. Lesson learned.