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ST Acrobat 3D

The ST Acrobat will do just about every 3-D maneuver that a pilot is capable of!

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Introduction


Wingspan: 1200mm; 47.24”
Wing Area: 37.8sq. dm; 586 Sq. In.
Weight: 1700g; 60 oz.
Length: ~53"
Servos: (4) Pre-installed
Transmitter: Futaba 6EX 6-Channel 2.4GHz
Receiver: Futaba R617FS 7-Channel 2.4GHz FASST Receiver
Battery: 14.8v Li Po 2200mAh
Motor: unknown Brushless Pre-installed
ESC: 40A U-BEC Pre-installed
Manufacturer: Sheng Teng Electric R/C Model Plane Co., LTD
www.sheng-teng.com
Available From: Tower Hobbies http://www3.towerhobbies.com/cgi-bin...&I=LWL149&P=ML
Price: $159.97

This airplane is causing a lot discussion because of two reasons: 1) what a fun plane to fly: and 2) very small investment. In fact I believe this plane should have a new category assigned to all ARF's: Fun Factor/Cost.

The reason I say this is because all the other pilots who have flown this plane all fell in love with it. Yes they say it is 3D and yes it will do all those type of maneuvers BUT tame down the control throws and you have one easy, smooth flying aircraft.

So if you are not into 3D consider this plane anyway because it will soon become your 'go-to' model!

ST Acrobat 3D - RCGroups.com (3 min 45 sec)

First Impressions:

When I picked up the ST Model’s Acrobat box I thought something was wrong – it was heavy – and big! Most electric airplanes are light but this one had some heft to it. Then when opening the box I saw why the box was a bit heavier than expected – the Styrofoam airplane was secured by a cluster of another type of heavy duty foam that protected the contents. None of the individual parts showed any signs of damage as they were removed from their thin foam ‘bags’ – not the clear bags usually found on most ARF planes.

Kit Contents

The airplane ‘contents’ included the foam airframe with two servos, motor, and speed controller already installed. The two wing panels also included their aileron servos already mounted waiting only for the aileron push rods to be installed. The servo leads from the ailerons were long enough to easily reach into the ‘hatch’ where my Futaba R617FS was mounted. In addition to the airplane parts, two (2) foam spinners were supplied as was a “Y” connector, winglets, pre-bent push rods (that actually fit!) and one propeller. An assembly manual was included and it indicated the procedure to install batteries in a transmitter – so I think this maybe offered as a complete package. And no, a 4 channel receiver was not included with this plane.

Assembly

With everything unpacked, it took less than an hour to take pictures, assemble and take some more pictures. So the term they use “Ready To Fly” I think is pretty close to being valid.

Wing

The initial action was connecting the pre-bent aileron push rod to the servo and securing it to the aileron horn. It was at that time I noticed the hinging of the ailerons – VERY smooth and has a rotation point inside the aileron and back from the hinge line. I think I will like this. The wing has a 40” carbon fiber rod running almost from wingtip to wingtip. After this was inserted in one wing panel, the rod was fed through the fuselage and the other wing panel was added. Two nylon bolts secured the wings and about 10 minutes had transpired.

Tail

The “Tail Wing” was then addressed. The horizontal stab (with elevator hinged) was then inserted into and through the fuselage. The only way to make an error in this process would be to insert the stab upside down but then the control horn would not line up with the servo so this is sort of a ‘fool proof check’ procedure.

There are two holes in the tail wheel bracket to hold the horizontal in place, but only one of them accepted a screw…that didn’t seem to affect the plane after some hard landings so I am not going to worry about that.

The rudder assembly did cause some concern because the vertical is held in place with a #3 x 30mm bolt that would NOT thread but did accept a #2.5 bolt (thanks to RTL’s Metric Assortment: http://rtlfasteners.com/RC/a.html). After pulling and pushing on the vertical, there was not a bit of concern that the tail would fall off, so let’s move to the radio installation.

Fuselage

Two servo leads from the rear of the fuselage (rudder and elevator) may have to be fished out of the spacious hollow fuselage. For this reason and to pull the two aileron servo leads outside the fuselage, they included a neat little wire with a hook on the end. No mention is made of this item in the instructions. I already have two other ‘tools’ similar to the supplied one that always seem to come to my rescue.

!Radio Installation

The elevator and rudder servo leads are long enough to be reached through the small battery access hatch in the bottom/front of the fuselage. Connecting the Futaba R617FS to those two servos might require a set of small fingers, so you may want to put them on order now (ha ha). The two aileron servos required a “Y” connector and had ample length to reach the receiver.

Now the (installed) Speed Controller could be connected to the receiver. Here is where you are on your own…what do you do with the receiver and its two leads? Where does the speed controller go and how do you attach them to the fuselage? No mention is made in the instructions so maybe you should order two sets of small fingers.

The opening for reaching inside the fuselage isn’t very large so you may want to remove the front cowling and access the bowels of the fuselage and place the receiver and speed controller wherever you can reach. Now insert the battery (2200mAh 14.8v)….what holds that in place?

Slips a bit side to side and fore/aft. Added some foam around the battery and that keeps it from moving. But the hatch is on the bottom of the fuselage meaning that in a high “G” turn, could the battery break through the hatch? Maybe I will have to do some maneuvers to test their design!

Being the chicken I am, some epoxy was used to coat the area where the battery will touch the fuselage and some Velcro added. Then some of the mating Velcro was glued to the end of the battery so the matter should be resolved.

Completion

The supplied prop (13/4) was mounted and one of two supplied foam spinners was secured to the prop shaft. The landing gear (with wheels already mounted) fits into the bottom of the fuselage and secured with a neat plastic insert that is held in place with two sheet metal screws. The good news is that the landing gear can be mounted and secured only in one direction (someone is going to have to invent a dumber idiot if these manufacturers keep making these thing Idiot-Proof!)

The instructions indicate a 140mm +/- 10mm location for the CG. To err is best to err on the positive side, so ½ oz of lead was attached to the cowl for the first flights. This brought the CG to 140mm and it is best to be nose heavy if it is going to be anything other than right on.

Flying

Basics

With only a gentle breeze blowing 45 degrees off center line the time had come. All of the Peanut Gallery was waiting (but panting-I wish they used mouthwash!) directly behind me as I moved out to the flight line. Even before I got a chance to advance the throttle, one of the “peanuts” was already asking if he could fly it – sheesh, some people’s kids!

Anyway, by gently advancing the throttle the Acrobat quickly accelerated and was airborne. Even at half throttle this little bird moves and is responsive. Full throttle it really gets up and goes – then throw in High Rates and WOW!!!! You have a tiger by the tail and this plane will do what you want it to do RIGHT NOW…slow it down and you have a gentle kitty.

In fact if you have a small area to fly, your entire flight can be done right in front of you, without any worries about tip stalling or if you are descending too much, add a click or two of throttle and she is now flying level! Add full throttle and you are in a nice gentle climb. Going too far left or right, input some aileron and some up elevator and she will be going the other direction.

Taking Off and Landing

Take-offs can be ‘selective’ by the use of the left stick…runway long? Gentle use of throttle and you have a scale-like take-off. Want a shorter one? Go to full throttle right away and some gentle up and within a few feet you are up, up and away! Quickly throttle back and you are in a hover! Landings can be similar – carry some power and stretch it out or slow the Acrobat down and it lands like a butterfly with sore feet!

Aerobatics/Special Flight Performance

Knife-edge was excellent – with only a slight tendency to fade toward the wheels. Inverted flight required “just a hair” of down to maintain altitude. A lot of 3D maneuvers are possible with this model – in fact I can’t think of one that it cannot do. The limiting factor in performing them flawlessly is the quality of the servos. Of the three different pilots (other than me), all three mentioned the need for better servo resolution/speed.

Now these guys are perhaps above the ‘average’ in skill, so I take their comments with a grain of salt because I saw all of them fly those maneuvers very well. When asked about how they felt about the plane they were very positive and when I mentioned the plane (and servos, motor and speed controller) costs only $149 from Tower no more comments to the negative were heard!

Loops and rolls can be very tight or quick; or VERY large and graceful. Stall turns are quick – one second you are going up, cut the throttle bang the rudder and BINGO – you are now pointed at the ground. Spins are nice and tight and remember this was done with a nose heavy Acrobat…and after a couple of flights I noticed 1/4oz had fallen off – and I didn’t notice any difference. Later in the week I noticed all of the nose weight had fallen off and I couldn't tell it!

Conclusion

I personally love this bird – it is small enough to fit into a car, uses probably the most common battery on the market, comes 90% complete right out of the box and can be assembled in less than an hour. I bet someone is going to bring this plane (still in the box) to the field and assemble and fly it the very same day…and then grumble they didn’t bring enough batteries!

Biggest problem with the Acrobat is the flight time – 5 minutes or less is best – I went 6 minutes + and I only had 16% left in the battery – not good……so THAT is the problem: this plane is just too much fun to quit flying…..so the solution is to get stock up on batteries and have a field charger handy.

As it turns out this plane is a winner - in spite of the instructions (heck, who reads them anyway?) .Take this plane with you and fly on your lunch hour, between church services and even while waiting to vote. There is a great thread for others who LOVE this plane at: http://www.rcgroups.com/forums/showthread.php?t=2250594. You can now add me to that list.

Is This For a Beginner?

Good question…..what is the definition of a beginner…..and a beginner of what? If you ‘know’ how to fly a trainer, and keep the Acrobat on low rates then YES. Rank beginner – no. Want to learn 3D stuff? Here you go! Can’t beat the investment in time or finances and they even give you two spinners ‘just in case’ <g>.

Flight Video/Photo Gallery

Last edited by tailskid2; Dec 09, 2014 at 01:29 PM..

Discussion

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Old Feb 20, 2015, 05:54 PM
J. Titors Gr Gr Grandpappy
Sonofagun's Avatar
Charlotte,NC
Joined May 2005
2,160 Posts
Size compare w/visionaire...
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Old Feb 20, 2015, 07:38 PM
Tommy Toy the Crazy Boy
United States, AR, Jonesboro
Joined Mar 2013
626 Posts
I haven't flown mine yet, but I hope to soon.
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Old Feb 20, 2015, 07:57 PM
Registered User
tailskid2's Avatar
USA, AZ, Phoenix
Joined May 2003
3,528 Posts
It is a lot of fun tmulligan.....let us know how it goes.
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Old Feb 20, 2015, 08:35 PM
Unregistered User
Eagle2Nitro's Avatar
United States, LA, St Francisville
Joined Apr 2014
1,459 Posts
As Sonofagun noted, the "Size comparison with a Splendor" picture is wrongly named. The other plane in the pic is a VisionAire.
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Old Feb 20, 2015, 08:40 PM
Registered User
tailskid2's Avatar
USA, AZ, Phoenix
Joined May 2003
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Yep, my bad.....
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Old Feb 21, 2015, 11:25 PM
Registered User
United States, MO, Fenton
Joined Jan 2012
2,932 Posts
Oddly this has been an overlooked bird. Quite a shame really. I take it with me most every time I fly. Thanks for writing a review. Next time I fly I will try to some 3d action on vid. Dan Landis from Hobbico made this video flying in his back yard. Gives a good idea of it's capability.

ST Model Acrobat 3D Aerobatic EP (1 min 50 sec)
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Old Feb 25, 2015, 05:45 PM
Obsession, not a hobby
T.A.Z's Avatar
United States, AZ, Phoenix
Joined Sep 2013
251 Posts
Tower's page says it has a 50A ESC.

Did you happen to get AUW on your model?
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Old Feb 25, 2015, 05:59 PM
Registered User
United States, MO, Fenton
Joined Jan 2012
2,932 Posts
Flying weight is 60 oz
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Old Feb 26, 2015, 12:47 AM
Registered User
Kopriti's Avatar
United States, AZ, Tolleson
Joined Sep 2010
23 Posts
It really is a great plane, I like it....
I enjoyed my short video appearance!! Lol
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