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Sunday, September 11, 2011

Parkzone Sukhoi SU-26XP Flight Review

I've heard mixed reviews at best about the little PZ Sukhoi, which immediately piques my interest. If most people don't like a plane, that can be an indicator of a fine intermediate-to-advanced flyer.

The mini SU-26XP didn't let me down. Although there is plenty of room for improvement, there is a lot of fun to be had driving this little aerobat.

On the Ground:

The plane has a nice high-vis color scheme.  Top-bottom contrast is limited, due to the use of the same colors which tend to blend at range.  The biggest different is use of yellow on the top of the fuselage and horizontal stabilizer.  Overall, I like the scheme and it works "ok" in the air, though top/bottom orientation is more challenging than it should be. 
This airplane is a classic mid-wing aerobat with a molded symmetrical airfoil, theoretically giving it the same or very similar flight characteristics whether upside right or upside down.  That works too. The wings are about 40% tapered with no washout for simplicity and symmetry.  All of the control surfaces are oversize, with large aerdynamic horns on the elevator and rudder for greater effect and less servo demand. 
Nice big control surfaces, but a non-adjustable rudder control arm hurts the best knife edge flyer in the HH micro line-up.
The ailerons are huge, consuming about 40% of the wing chord, making them very effective at high and low speed.  They do not extend to the wing root, so they aren't blown by the motor when airspeed approaches static in harriers and hovers, perhaps adding to the difficulty the SU-26XP has trying to pull these maneuvers off.
The landing gear struts are nicely rounded, like the real airplane--a nice touch.  They are easily removed for a little less drag when hand-launching and ditching over grass.

For $100, the plane seems like less of a ripoff than most Horizon Hobby micros, but I would like to see it selling for more like $49 to see it better compete with other Chinese imports in its utility range. There aren't many other microbats on the market, but much larger aerbats sell for a similar amount of money.  We flown and reviewed several of these top notch performers in their price category.  They need a little more space, but not much and are more resistant to wind.  For example, this 30" span balsa and ply Yak-54 PnP is $60, or $90 with a 6Ch Tx and Rx:
This Katana requires a receiver and an ESC, but it's also a big 45" span balsa and ply model for $119:
This 36" Pitts is $79 as a PNP, $100 as an RTF:
This AT Yak-54 is a Z8RC value favorite with a 36" span and a 4Ch RTF price of $99:
As dominant as the models above are when compared to the capabilities of the PZ Micro Sukhoi, I was unable to find anything on the market that directly competes--a tiny, scale indoor/outdoor aerobat.

There are some flat foamies that are in the same size category, like this TechOne Piaget or Yak-54 (both airframes run $24):

But these planes both have the exact same exterior dimensions.  I mean come on, there is nothing Piaget (whatever that is) or Yak about either one of them, they are flat foam flying thingies with different printed color schemes and slightly different die cut profiles.

Part of the problem with going small is Rx size, some of these micros are under 1 oz total flying weight.  It seems that until someone comes out with a decent, 4ch bind-able truly micro Rx, besides Horizon Hobby, it looks like they have a monopoly on the scale UM market.  HH has license to release wildly over-priced and under-performing model after model, and the Su-26XP is no exception.  It contains about 2 cents of foam, reflects about $5 of foreign slave labor, a few dollars in common electronics and a 5 cent brushed can motor. 

Just to let some enterprising company know, if they came out with a high quality scale UM foam series that was bindable to any radio standard or even a proprietary one, I would pay a few hundred bucks or more for better quality than HH disposable junk without thinking twice about it.  An optional tailored hard shell case instead a giant foam box would be a huge bonus; obviously portability is the idea here.

All that said, the Su-27 XP is fun to fly and somewhat portable, at least while it lasts.  And it is "only" marked up about 20x to $100, a welcome relief from HH's usual 40x markup for their cheaply made, foam planes.

In the Air:

As I suspected, the S-26XP is a good aerobat.  A lot of people seem to think it is too unstable or unforgiving, but I found it very manageable, even mildly forgiving.  There are a few things it does very well.  Let's start with those. 

The one thing the micro Su does best, better than all other UMs, is knife edge flight.  Unfortunately, you have to have a programmable radio to do it, as it requires setting 120% rudder deflection, as the plane's physical control horn travel adjust is non-existent: there is only one hole (shown above).  With 20% more rudder, the Su knifes very well indeed, and rudder control at 90 degrees of bank is almost uncoupled.  It can even pull off a knife edge loop, though you have to be pretty high for the cheap brushed motor to reel-in the fall on the backside.

Another thing the plane does well is slow flight, though you have to stay right on top of it.  In this area, I need to distinguish between capability and effort level:  It has the capability to fly very slow, but it takes a lot of effort. In my last review, we saw the opposite, the triangular Stryker 180 flies slow rather effortlessly (just needs a ton of trim) but its slow flight capability is a more limited than the Su.

Flying the Su at high alpha requires attention.  Fortunately, neither the rudder not the monster ailerons washout, give you the ability to stay on top of the airplane as the wings or tips stall.  Even though the plane can be prone to sliding off to one side on a whim, you can upright it with timely control inputs.  This is especially helpful is slow turns, when the plane is most likely to want to roll over.  With steady but predictable guidance, the plane turns out to be an excellent nose high slow flyer.  The huge battery position allowance of the velcro lined belly, makes this trait even better and facilitates a lot of fun.

The best way to fly slow is to lighten up the plane with a lighter, smaller, more powerful and longer lasting (as in, time between buying new replacements) Hyperion or Turnigy 1S battery.  The induced 150mAh 1S is poorly constructed, heavy, and low voltage, resulting in a significantly lower thrust:weight ratio than is really necessary.   I flew my UM Su with a 138mAh Turnigy 1S with noticeably higher flight performance.

Here is my second flight, using the better 138mAh battery.  Not a lot going on but general flight characteristics testing.  Decent, beautifully uncoupled knife edge at 2:20:
The neat thing about flying the plane slowly is the ability to force a stalled wing back to level with the enormous ailerons.  At about 40% of the total wing area, the ailerons are so big they work all the time, even to right a stalled wing.  Working after a stall is the best definition of 3D capable.

If the Su had more power, it would be a fantastic 3D machine, but as sold the wimpy five cent 8.5mm brushed can motor and gearbox are barely adequate for aggressive conventional aerobatics.  A brushed motor is in this airframe's near future.

Aside from the loser power system and monster ailerons, the rudder is extremely effective but too throw limited to overcome the plane's lack of blowing power.  Knife edge flight is outstanding, but only possible with a computer radio set to 120% rudder throw.  Oddly, there is no physical throw adjustment with the stock control horn.  The plane can't balance on the prop as a result.

Elevator effectiveness is fine.

Float is adequate but not satisfying with the supplied 150mAh battery.  It is much better with a lighter Turnigy 138mAh.  Wing loading is a touch high for the planes unstated mission.  Adding a brushed motor could weigh the plane down even more, but I think it could still be an awfully fun flyer given enough power and vastly improved tail surface blowing.

In stock form the Su-26XP is a ton of fun, but it falls short in the power and throw dept to fulfill any hope one might have of 3D'ing it.  It just can't must the power and throws to match the raw capability of the airframe.  That said, the airframe seems to have a bad wrap as a poor flyer, nothing could be farther from the truth, the form flies great, but is let down by the Parkzone guts.  The ultra-cheap power system and tail throws limit the Su to more conservative maneuvering to keep out of 3D trouble.

Appearance: B
Nice looking airplane.  Top/bottom color scheme is too similar in tone.

Airframe: A
Great raw ability.  Needs more throw or blow--no surface throw adjustments.

Power System: D
Let down by 5 cent brushed motor.  Decent battery life.

Build Quality/Durability: C-
As good as Parkzone gets - below avg.

Value:  C+
Not as pricey as most HH micros at $99.

Overall Grade: B+
Very nice handling plane.  Ripoff motor.

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