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Friday, May 13, 2011

Art-Tech Yak 54 Review

Update:  please see: http://z8rc.blogspot.com/2011/02/fixing-art-tech-yak-54.html

Update: March 20, 2011 - The AT Yak 54's lack of precision, as noted below, was later discovered to be attributable to all 4 of 4 defective DX8  potentiometers.  I apologize to Art-Tech, I mistakenly blamed them for Horizon Hobby's FUBAR radio.  The ATY54 is simply exceptional for the $; fix the grade to A+.

After owning several (with another on the shelf, unopened) gorgeous Art-Tech Pitts S2B biplanes, I had to try their very reasonably priced Yak 54 RTF.  Warning: for those who go to auto races to see cars crash, there is no disappointment here.  Like their Pitts S2, the A-T Yak 54 is a terrific flier.
One badass machine; the plane isn't half bad either.

Unfortunately, the OrangeRx receiver I stubbornly re-tried, wasn't nearly as good as the plane.  The rx caused major binding/unbinding/trim/re-trim issues throughout the flight, but bottom line first:

The Yak flew wonderfully when the Rx wasn't freaking out.

Kit Quality and Value:

A-T's Yak isn't setting new records in foam quality, best described as beer cooler Styrofoam, but they are setting records in the important area of value.  Both their Yak 54 and the PittsS2B run about $150 in RTF form (with a surprisingly nice 8-AA Tactic 4ch Tx and 6ch Rx).  Declining the radio/Rx gets you down to about $130, ready for your own, painfully expensive Rx.  The A-T package dutifully adds a quality 1300 mAh 3-cell to your collection, and you'll need to find another plug for the 0.3 to 1.0 Amp dial-a-rate Lipo charger.   I love these chargers: you plug the battery in; it charges.  Imagine that.  No needless gadgetry supplied, required, or desired.  13 minutes of anti-gravity indicates approx 1min/100 mAh ordered up from the engine room.

What a great way to log some cheap, high quality airtime.  As far as expected durability, well, there are two things to consider--neither is good:  1) The foam dents very easily and 2) it isn't the strongest structure you can get on the far side of $100.  That said, it is RTF.  A $100-range balsa and ply super-strong structure will come in ARF form, and the "A" stands for "After a lot of work and money."

The Yak was packed very well and assembled with reasonable care.  Basic construction is a two-piece fuselage (top is removable with a single screw), a one-piece wing that drops into a molded cradle while the top fuse is open, lightly tighten one nylon wing bolt to pin the wing in the middle, add the one-piece horizontal and single-piece vertical stab.  The aileron hinges are pre-taped and the tail surfaces use molded foam hinges.  I elected to tape the rudder hinge with scotch tape, since the tail wheel transfers the plane's weight directly to the hinge.  Speaking of the hard plastic tail wheel--this is the one poorly executed part of the plane--you'll want to pick up a rubber-tire wheel and some piano wire to bend your own.  Mine took less that 10 minutes to form and replace using a needle nose and regular pliers--but I've bent a lot of tail wire.  I secured the bottom-rudder-into-fuselage tab with 2-dots of Guerrilla glue for a little more tailwheel strength.  The vertical stabilizer is a bit fussy to pin with the supplied nylon sandwich braces and screws.  I glued the final taper of the fuselage halves to the sides of the small, slide-in vertical stab, for fear of the huge movable rudder not having a whole lot to cling to.

I guess there is one more poorly executed part: the spinner.  The rubber cap spinner didn't last my first run-up, plan on getting another.  I wound up painting a Parkzone Fw-190 spinner; a perfect fit.

The Yak looks big, but the 39" Beaver, 41" Edge and 48" Cub are bigger.
Airborne

This is a pilot's airplane. It is light, maneuverable, and highly predictable.  Art Tech selected a solid power solution for the plane: a gear-reduced brushless in-runner with gobs of torque for the small size and reasonably light weight.  This setup lets your turn a big honkin' prop at relatively slow speeds.  Hovering is not a problem, but power delivery feels measured at times.

The gear & motor noise is great, specially if you like a lot of noise and your neighbors do too.  In a high speed dive, the whirling Yak starts to sound like a three way cross between the punctuated snarl of an old Allison V12, a high speed blender crushing ice, and an 70's pickup truck dragging a loose roll of chain-link fence over to uncle Billy's double-wide.  Like it or hate it, it delivers.

Traditional aerobatics are no problem for the Yak, but it is hard to resist the urge to square corners.  Carving graceful lines in the sky requires tediously tracing your imagination, rather than the natural result of a smooth trade between G and airspeed.  High load, high precision maneuvering, like established knife edge flight, is an area the where the Yak's Styrofoam becomes needy.  I'm not exactly sure where the line falls between me sucking and the foam bending, but there is a blurry area somewhere in the shades of gray.  I think I can add some fiber rigidity on the cheap.  Thank God for the feather wing loading, this thing has a lot of potential.

The RTF's aft CG is especially pleasing and a little challenging.  The designer was quite serious or just a little bit stupid.  This tail is totally alive and it needs forced air to function.  Blowing the tail up with throttle sets the plane level with the horizon, the tires tear into the pavement resulting in pretty good top end speed.  Unzipping the sky rapidly in the horizontal is always one stick bump from inserting a 90 degree corner.  Fun.  A little darty.  Fun.

Suffocate the tail with idle power, and the license plate droops while the 54 gasps for air.  The resulting high-alpha flight keeps the plane from doing the expected, simple search for airspeed.  Instead, the Yak holds altitude with a slow pitch up until the wings give up the ghost without rocking.  The lack of wing loading keeps it airy.  At the point the clever little plane runs out of airspeed and interesting new ideas, it begrudgingly sets a reasonable glide attitude; only because it is falling like a brown leaf in late October.  The high AoA glide path progresses in the general direction of the pilot's toes, only slightly steeper than the Shuttle getting ready to swap ends at Edwards AFB.  Adding a teaspoon of power to avoid the impending belly-flop transitions to horizontalish flight, better aligning the wind with the nose, followed by a touch of eagerness to raise the nose back to blue.  Pulling the power out again resumes the sink and the plane hunts for a place to pancake.

Add 30% power, keep it there, and you are ready to spot  land.   Alternating blender buttons between "aerate" and "puree" lets the airplane down under control, tail wheel first.  And why not?  Controlling the Yak's decent in the flare is as easy as goosing the power just before the shadow touches the rear wheel.  Landing rolls are reminiscent of catching the approach end cable with the hook.   The cheap landing gear is plenty long to protect the prop from a minor tussle with pavement, but the Yak is fully capable of nicking one prop per flight.

At 19 oz out of the box, the plane has a lot of potential as a 3D trainer/contender, but as perhaps as expected at this price point, a few things are in serious need of improvement. Rather than beat an inexpensive plane up because it isn't perfect, I'm going to stop here and give the A-T Yak an A- for superb, low budget flying qualities with a few significant execution errors.

As usual, I'm not going to complain without showing the fixes. I'll keep it cheap and limit the work to a few hours so we can stay fun and low risk. Good news is, it's not hard to turn a fun foam sponge, based on a killer foundation, into a 3D scalpel.  Look for another post within a day or three called, "Fixing the Art Tech Yak 54."
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