E-flite Pitts S-12

E-flite Pitts S-12

Build quailty is very good and helpfully, the potentially tricky strut work has been taken care of.

The Pitts series of aerobatic biplanes has long been an aeromodelling favourite. Although the classic Pitts Special first flew in 1945, the Model 12 was the last variant to be designed and developed by Curtis Pitts himself and first flew in April 1996.

Nicknamed the Macho Stinker or Python and designed around the Russian Vedeneyev engine, its a 21 – 23ft span tandem two-seater, capable of cruising at 170mph. Pitts wanted to make an aeroplane that was a match for the single wing aerobats of the time, such as the Sukhoi SU-26. Endearing through the original Special may be, the S-12 is without a doubt my favourite example of the breed.   

This new E-flite model is based on the 17th example, built in 2003 and owned / flown by Keye Kaitis in the US. It spans 40 (approx. 1/7th scale) and has been designed by Quique Somenzini around a brushless electric power system, specifically E-flites Power 15 or 25 motor.

The Model requires a 60 amp ESC and power from 3s 4200mAh or 4s 2200mAh Li-Po batteries, battery size being dependant on the motor chosen. This Pitts is the perfect size to stay in one piece between flying sessions and should fit into the average car easily enough without disassembly.

She’s a very pretty aeroplaneBUMF N BUILD

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E-flite sets high standards where instruction manuals are concerned and it hasnt dropped the baton here. Mind you, although its radio set-up suggestions are helpful, theyre somewhat slanted towards its own product range. Thats fine up to a point although Id like to see servo ratings mentioned so torque requirements can be easily compared and matched.

 In this respect JR MC35 analogue micro servos are suggested, although the elevator and rudder fuselage cut-outs are configured for mini servos. For the review model I used four JR DS385s – 2kg torque micro digitals that continue to serve me well in my SebArt Katana 30. Theyve been fine in the Pitts too, although it was necessary to narrow the rudder and elevator apertures with my own home-made ply servo mounts.

Construction of the Pitts is entirely typical in ARTF terms. The quality and fit of parts is generally fine and the only adjustment I found necessary concerned the tailplane seat, which needed some sanding to get the surface at 90-degrees to the fin.

The wings have pre-fitted strut connection points and with the fuselage cabanes also pre-fitted, the process of mating both wings to the fuselage is very straightforward. Theres certainly no need to fret over incidences!  
I fitted an E-flite Power 25 motor for which stand-offs are included in the kit to help project the motor mount, this so that the prop can extend just beyond the dummy engine moulding. Incidentally, its well worth taking the time to cut, fit and paint this dummy engine cover, for the model looks so much better with it in place.

Hardware quality is very good, the clevises and horns in particular are heavy-duty items while the wheels and metal undercarriage legs are easily up to the job. Oddly for E-flite, the spats look to have been hurriedly made, exhibiting some rough edges on the underside. Still, theyre very strong nonetheless and have coped well so far, without sustaining damage.   

E-flite seem to have been listening to their customers as the undercarriage assembly is stronger than a good number of comparable models Ive seen over the last 12 months. Here, a balsa fillet sandwiches the undercarriage plate and securely locks it in place. The arrangement isnt indestructible but it shouldnt punish rough landings by letting go and taking the underside of the fuselage with it.  
    

Tail brace wires are supplied although the manual admits they add nothing to the structural integrity and, if you ask me, even less to the finished appearance! Result? I havent fitted them. I normally omit pilots in my out and out lightweight electric aerobatic machines but Im still in two minds here so I may still pop a bod in the office further down the line.

The small wheels and spats make ground handling less than easy – I fitted bigger wheels after this shot was taken which has helped a lotPITTS POWER
E-flite make two power package suggestions for the model – a lighter 3D set-up and a heavier sport arrangement:

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3D – Power 15 950 kV brushless outrunner; 60-amp ESC; 2070 mAh 4s Li-Po; 11 x 8 prop.

Sport – Power 25 brushless outrunner; 60-amp ESC; 4200 3s Li-Po; 12 x 8 prop.

I opted for the latter set-up, partially as my Power 25 motor was looking for a home and because I feel this lovely near-scale model would be wasted without a good sport aerobatic capability. To be frank I reckon Id look a bit silly moving through a 3D repertoire, after all, have you seen a full-size Pitts S-12 prop-hang? No, me neither!

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Measuring a 38 amp current draw on a 3s battery and generating 420 watts using a 12 x 8 prop, Ive arrived at a figure of 140 watts per lb; the static thrust is impressive, too.  

On the battery side of things, E-flites suggested 4200mAh 3s Li-Po is a bit of a squeeze for the bay and brings the C of G too far forward. The model balances nicely with a 3s 2500mAh FlightPower EvoLite pack (weighing 196g) although flight duration hasnt been as long as I would like, perhaps 5 – 6minutes with careful throttle management. A slimmer, longer 3300mAh 3s FlightPower pack just about slides back to achieve the C of G and provides about 7 – 8 minutes of flying. Mind you, the model may balance better with a heavier battery if larger servos are employed for rudder and elevator.

The use of four micro digitals demands some thought regarding the need for a separate receiver battery. In order to keep the weight down Ive used a switch-mode ESC, specifically an E-flite 60 amp Pro – a unit that can handle the demands of up to six standard size digital servos and take current from 3 – 6s Li-Po batteries without the need for a separate receiver battery or voltage regulator. Theres some debate in electric flight circles about whether these ESCs generate their own noise, although the answer is to fly with 2.4GHz. Truth is, Ive used this ESC in several models and it hasnt blinked once when flown using 2.4GHz radio.

Smooth and precise, the more I fly her, the more I like herPILOTS NOTES
The low control throw rates suggested by E-flite are a good starting point yet deliver a pretty sprightly sport aerobatic repertoire, so do start with these and adjust afterwards according to taste. I always seem to fly with 20 – 30% exponential on elevator and ailerons these days, indeed the set-up on the Pitts is no exception. It just makes everything nice and comfortable without having to play around with dual rate switches.    

As I say, the power from my system isnt in doubt and although the model needs a little elevator to keep the tail down as she starts rolling, this can be relaxed slightly just before the aeroplane rotates. And rotate she will within a surprisingly short distance! Climb-out can be pretty near vertical so you may choose 3/4 throttle if a more sedate and scale-like take-off run is preferred.

My model required a few clicks of trim here and there during the first flight but was soon tracking straight and responsible for that satisfied smile that all good models have a tendency to provoke.

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Ive found that all the bipes Ive built and flown have excellent stall handling characteristics – in part thanks to relatively large wing areas and low wing loadings. Anyway, this Pitts is no exception. With power steadily reduced and elevator gradually fed in, the S-12 will just wobble and mush, occasionally a wing may drop but everything happens slowly and she can be picked up quickly with throttle and ailerons.

As I say, the roll speed is impressive even at the suggested low rate setting, and inverted flight needs just a touch of forward pressure to maintain straight and level. Of course, it should be remembered that since the C of G position will affect handling, careful battery placement before each flight will ensure that the model exhibits consistent trim and performance. Incidentally, make sure the flight battery is retained with something more than just a strip of Velcro. The battery hatch, while secure, would quickly part company with the model should the weight of a battery fall on it. I use a couple of cable ties to provide that reassurance.

Knife-edge flight is better than Id have believed for a model of this sort, yet I guess the wide fuselage and wing struts must help keep her tracking. I just love the way any aerobatic biplane spins and flicks, the two wings and compact appearance always seem to enhance the impression of travel and movement, indeed the Pitts is fantastically agile when the sticks are in the corners. She never feels like shes running away from you though, and recovery is very straightforward.

Occasionally, just occasionally, I feel the need to add a little rudder to help the model through turns, particularly during a slow climb out, yet the trait seems insufficient to mix in some coupling at the Tx.  

Biplanes have traditionally been regarded as quite draggy affairs, yet the relatively thin wing section makes this one more slippery than you might expect. As such, it can have quite a high approach speed when lined up for landing. Lots of drag means that many biplanes sink quickly when the power drops off yet this one just wants to keep on going. It sounds obvious but its important to ensure that sufficient speed is bled off during the approach. The model shouldnt bite and balancing throttle will bring her in for a nice three point touch-down. Actually, a three pointer must be the objective here as the large 12 prop can easily bite terra firma and flip the model over; something thats to be avoided as the tail will undoubtedly suffer if this happens when the Pitts is moving fast. Short grass will ensure that a nose-over is also avoided as the Pitts comes to rest, that is, unless insufficient elevator is held in to keep the tail down until she stops rolling.

As I mentioned, the meaty undercarriage arrangement and tough spats should put up with a level of abuse that lighter aerobats wont withstand so a gentle landing in the outfield shouldnt be the disaster it so often is with more fragile arrangements.  

Remember to keep a little power on just after touchdown so as to keep the tail down and the model from nosing over (smaller wheels pictured)SPECIAL?

Try as I might Im struggling to find any negatives where this model is concerned. Well, I guess the battery bay should be mentioned. The location and the size of the area within has been designed with the 3D flyer in mind so as to keep the battery high in the fuselage. Thats fine but sport flyers may find that surgery is required to remove a little wood and squeeze in larger 3s Li-Po packs of the 3000-plus mAh variety. In truth, then, a more flexible arrangement should really have been designed in.    

This Pitts will suit intermediate or advanced pilots seeking a near-scale aerobatic model thats just a little different, yet precise and comfortable in the air. E-flites Model 12 is a rugged machine, its well made, complemented by good instructions and its hugely attractive, a real head-turner in fact. Its big enough to cut the mustard on any Sunday club flightline, yet small enough be transported in any medium size (perhaps smaller) family car without disassembly.
I could add that it’s nice not to have reviewed another Extra, Edge, Yak or Sukhoi derivative, a sentiment that, whilst true, is probably an unfair comparison.

6 MONTHS DOWN THE LINE…..

This is a model that’s really grown on me over the last 6 months. Don’t get me wrong, I really liked it right from the off, but it has a real pedigree quailty that’s steadily become apparent over time. Coming from Mr Somenzini’s drawing board, I guess this shouldn’t come as a surpsise though. I fitted larger wheels which has improved the ground handling and means the model doesn’t now nose-over when landing (providing a little power is maintained to keep the tail down).

There have been occasions when I’ve reached for the Pitts in preference to more aerobatically capable models simpy because the Pitts looks nice and ‘scale’, is smooth in flight, and never ever drops a wing or does anything to upset. The motor I used (Power 25) is just perfect and hauls the model round with gusto while I now use 3200mAh 3s packs which provide about 8 mins of flight. All-in-all, a very fine aeroplane.

 

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