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Old Mar 10, 2012, 11:10 PM
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Extra 330 Review

Hi all, I just wanted to share my experience with this plane since not much information is out there yet.

I placed the order last week and received the plane in 3 days. The prop shaft had poked through the box but wasn't bent or damaged. Everything else was in good shape. Assembly was relatively straight forward. The instructions were terrible, very small pictures detailing each step. I did have trouble with the provided pull-pull setup for the tail wheel but I am not that experienced of builder. I ended up purchasing a different setup from my local hobby shop and that worked fine. The mounting screws for the control horns are excessively long, they protrude pretty far out from the control surfaces. I haven't decided whether or not I'm going to cut the screws, get new ones or just leave it as is. I would say the total build time for me was around 2-3 hours. I did take my time and made sure everything was lined up properly and secured.

On to the flying. I was able to fly her pretty much all day today (15 flights or so). On my maiden I did have to do some trimming (up elevator and right aileron) for the first half of the flight to get her to track straight. Once I got her dialed in she tracked beautifully even in a bit of wind. She flies relatively slow at 1/3 throttle, but I ended up flying her around at 3/4 throttle most of the time. She was able to climb vertically and perform all the aerobatics I'm comfortable executing. I'm not sure about 3d capabilities since I'm a newer pilot. I did have a couple tough landings and the gear held up fine. I was flying with Turnigy Nanotech 2200 4s 35C batteries pushed all the way forward and she was a couple mm tail heavy. She could definitely fit much larger batteries, I will get around to measuring the battery compartment one of these nights.

I've attached a few pictures for you since nitroplanes doesn't have any yet.

I'll try and get a video tomorrow weather permitting. Feel free to ask any questions.

-Jeff

http://www.flickr.com/photos/7782812...th/6971387683/
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Old Mar 11, 2012, 08:09 PM
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Your Extra looks really nice bro!
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Old Mar 12, 2012, 05:30 PM
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its sexy and he knows it!


wiggle wiggle wiggle wiggle!
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Old Mar 24, 2012, 06:15 PM
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has anyone figured out how to get the cowl off without tearing it up? I've pulled and pulled until I thought it was about to break with no results. Aslo ran a flat ruler all the around through the slot but prying in the slot would distort the foam.
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Old Mar 24, 2012, 07:36 PM
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Quote:
Originally Posted by davidgp View Post
has anyone figured out how to get the cowl off without tearing it up? I've pulled and pulled until I thought it was about to break with no results. Aslo ran a flat ruler all the around through the slot but prying in the slot would distort the foam.
I purchased the kit version (no electronics) of the Sbach. I've had no trouble removing the cowl. Mine was not glued - just press fitted.
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Old Mar 24, 2012, 07:45 PM
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more progress on kit build

Quote:
Originally Posted by jokeane View Post
I've got a Turnigy SK4250-650kv which should work well with the supplied 15x7 prop - which appears to be a clone of the APCe 15x7 prop.
I've got the SK4250 motor mounted. Just drilled new holes in the included motor mount bracket. Stock motor must be almost the identical length because everything lines up perfectly. With the prop adapter supplied with the SK4250 it just clears the front of the cowl with a bit to spare. I did some power testing with a 4S 3700mAH battery and the 15x7 prop. Pulled 47 amps, ~670 watts input.

I got the landing gear and tail set assembled. Had to de-warp the elevator with a heat gun, mine was slightly curled. I also cut a bit of foam off the horizontal stab to 'bevel' it - needed to do this to get a full 45 degrees of deflection on the elevator.
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Last edited by jokeane; Mar 27, 2012 at 07:08 PM. Reason: spelling
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Old Apr 08, 2012, 11:00 AM
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Flight report - first two flights

Finally had a chance to fly the Aerosky Sbach on Friday. Very nice maiden flights. I ended up using only a 4S 2200mAH pack (30C) since that is all that will fit without modifying the foam. Only 5 to 6 min. flights on those small batteries. I'd say it seemed a tad tail heavy, but I'm not 100% sure. More flights with a bit more testing to be sure of the final CG. (I was at about 100mm for these flights).

With the SK4250-650kv motor, I was getting 700+ W input, AUW a bit over 4lbs. Enough power for nice spirited performance. No problems on take offs or landings - it did not feel 'heavy' in the air or present any tendency drop a wing as I slowed down for landings.

My only criticisms are the slight warping on the elevator and ailerons (due to paint being solid on bottom), the lack of 'standard' parts in the design - motor mount, spinner, .etc. which I mentioned earlier. (I ended up gluing the spinner on). If this ARF was designed more like a Multiplex kit, which are designed to accept 'standard' motors, batteries, .etc, it would be truly excellent.

The mini metal gear servos (5, since the elevator is split) seemed to perform OK. Enough throw for 'low rates' loops, rolls, knife edge flight and stall turns. I'll try some more extreme maneuvers next time out.

Oh, one last thing to be careful of - the canopy acts as a solar magnifier and will quickly turn the black foam inside the canopy into 'alligator hide'. Best to cover the canopy if you have it out in the sun (or in your car). This happened to mine in just two hours of Wisconsin spring sunshine. So take care!
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Old Apr 08, 2012, 02:33 PM
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Nice looking plane.. thank you for the update
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Old Apr 08, 2012, 08:27 PM
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My Extra 330SC So Far...

I received my Extra 330SC ARF this week. I haven't had a lot of time to work on it, so itís not flying yet, but I have it far enough along to pass on some info, and ask a couple of questions.

First impression: Itís an extremely nice foamy: Nice paint and decals; big, with a somewhat heavy feel to it. The UPS invoice said shipping weight was one pound Ė yeah, in your dreams. This model seems to be more oriented toward being a scale model of a sport airplane, rather than being a serious, real 3D aerobatic airplane. The pilot figure is surprisingly detailed and well painted, and the foam is very smooth with nice details like rivets and panel lines. The model is pre-painted with decals already applied (ďwater-slideĒ decals Ė not stickers), and it looks great. I wish I could have applied the star decals, though, because they arenít really aligned the way they should be. Thatís a nit though, and Iím very pleased with the look and general quality of the model Ė especially for the price.

I had read in a thread on the Aerosky Sbach sister plane that the Sbach has pin-hinges on the control surfaces, so that was what I was expecting on the Extra. Sad-face: The surfaces on the Extra are all hinged via the foam that is part of the airframe. I didn't like the resistance they put on the servos, so I bought some hinges and decided to cut the ailerons off the wing. That's when I noticed how warped the ailerons were. The ailerons were warped downward at both ends, with a little bit of a sinusoidal action in-between. When I cut the ailerons loose, the warps got even more pronounced. I thought I was going to have to build some new ailerons, but by installing them with four big hinges on each surface, they straightened back to the way they were before I cut them out. The warpage was still unacceptable, so I got some flat carbon-fiber rods and glued them vertically to the trailing edges of the surfaces with CA to hold the surfaces flat. That pretty much took care of the problem (pic below). The ailerons are now more or less flat, and move without resistance. Now my only concern is control surface flutter due to the additional weight on the trailing edge. I may have to put some weight in the counterbalances of each aileron tip. Iím hoping not, because even though the carbon fiber rods didnít add much weight, it seems the airplane is pretty heavy as it is. After dealing with the ailerons, I chickened-out of re-hinging the rudder and elevators Ė for now, at least. The surfaces are not warped, but the current foam-hinging limits the control surface movement somewhat.

Due to the wing-tip-to-ground clearance, I probably wonít use the Side Force Generators at first, though I may put some kind of skid in their place to protect the tips until I can grease the landings. Iím undecided on whether I like the looks of the SFGís yet or not. Iíve never flown with any before, but I hear they really help stabilize an airplane in knife-edge flight.

Although it hasn't flown yet, I have the airplane put together enough to take some data, so hereís what I have so far: Weight with battery is 4 lbs., 10 oz.; 11.1 oz. of that is the HK Zippy 4-cell, 2650mAH, 40C battery, versus the spec weight of 4lbs, 1.3 oz.. Maybe spec weight doesnít include the battery...

Since the receiver, battery, and wires are just sitting loose right now, I havenít measured the C.G. yet. I was able to do a power check, though. With the stock motor and the fully-charged 4-cell Zippy battery, the power specs are 730 Watts and 50.1 amps at full power. So, hereís my concern: While Iím very happy with the 730 Watts, I am concerned about the current draw. I couldnít find a spec for the ESC in the instructions or on the box, but Nitroplanesí web site says the ARF comes with a 45 amp ESC! Can anyone with a stock model tell me what kind of Watts and amps they are pulling? (jokeane: I see you are pulling 47 amps with your custom set-up. What ESC are you using?) I may have to get a 60 amp ESC, but then I start wondering if Iíll melt the motor, Ďcause who knows what the max current rating for the motor is? With that power set up and the provided prop, I measure 6 lbs static thrust, which will give me a 1.3 thrust-to-weight ratio. That will be great Ė at least until the motor becomes a molten slag in the cowl! Thoughts and comments would be appreciated...
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Old Apr 09, 2012, 06:12 PM
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Quote:
Originally Posted by DriverRX8 View Post
(jokeane: I see you are pulling 47 amps with your custom set-up. What ESC are you using?)
I am using a Turnigy 60A ESC. Depending on which battery I use the 15x7 prop pulls 47 to 51 amps static.

I can say with the Sbach it felt more like a scale aerobatics plane than a 3D plane. It isn't quite as light and rigid as 3DHS or Hyperion planes of the same size. But I also didn't try to push the envelop on my first two flights, so too soon to say for sure how it will fair performance-wise. Scale looks are very nice indeed for a very quick build. I would say it compares well vs. a Multiplex foamie, except for the non-standard parts issues.

I understand the draw of the RTF setups, I just wish they would design these so that if you want to use your own hardware it isn't quite as much of a hack-fest. For example the included spinner will ONLY fit the included motor mount which only fits the motor designed for this kit. The spinner isn't designed even to fit other size props, crazy!

My friend that has some large size foamie warbirds (FMS and others) is of the same opinion about non-standard parts issues.

Hey Nitroplanes / Bananahobby / Aerosky, .etc if you are listening, please pass this along to the guys designing these planes. Offer an 'ARF/KIT' which can use 'standard' motors/ESC/servos/batteries without massive modifications - and by all means also offer a RTF version with your house brand stuff as well.

-Jim
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Old Apr 11, 2012, 10:22 PM
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So my C.G. ended up around 105.0mm, instead of the specified 85.0mm. What C.G.s are you other Extra flyers flying at? What is a recommended "real" C.G.?
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Old Apr 13, 2012, 07:05 AM
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Quote:
Originally Posted by DriverRX8 View Post
So my C.G. ended up around 105.0mm, instead of the specified 85.0mm. What C.G.s are you other Extra flyers flying at? What is a recommended "real" C.G.?
On the SBach they recommend 90mm in the instructions.

My CG is closer to 100mm on the Sbach. Seems pretty good in flight. Perhaps a bit nose heavy. I did the dive test yesterday and it appeared to 'pull out' of the dive - which indicates that it is nose heavy. I've not flown inverted much - that is the other good way to tell if your CG is right on or not.

Since my CG worked out to 100mm w/ 4S 2200 30c packs, and they fit without modifications, that is what I've been using.
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Old Apr 13, 2012, 07:11 AM
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Got two more flights in last evening

Did a bit more aerobatics than on the maiden flights. Tracks very well, holds knife edge very nicely. Snaps were pretty nice. Aileron rolls at about 1 per second. Landings are pretty straightforward and easy.

I'll need to adjust my control throws. So far I've been on 'low' rates, which actually seem too aggressive for 'low'. I've not even tried high rates.

After these two flights I found my landing gear was a bit loose. Also one of the wheel pants has a crack in it. Odd, since I've been 'greasing' my landings from the start. But the field is grass, and not exactly smooth. I re-tightened the screws, but it is hard to say what they screw into and if that surface is stable.
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Old Apr 13, 2012, 10:30 PM
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Your report adds fuel to one of my suspicions, jokean. My Extra is ready to fly, so I've been programming my transmitter. It seemed to me that there was an awful lot of control surface moving even with expo and d/r set high. I did some high-speed, almost-flying taxiing today (way too windy and gusty for maiden), and the controls still seemed overly-sensitive, even with high expo. I think I'm going to set up three different flight modes that will allow me to switch immediately between three different expo and dual-rate settings in flight, in case I need to. My only other remaining concern is the ESC that came with the ARF. I can't tell what the amp rating is, and I just find it hard to believe they would only put a 45amp in (according to NP website). I will probably do some ground runs and see how hot it gets. Changing the ESC would be a real PITA, since I can't get the cowling off to connect the motor.

For anyone else working on this airplane, I thought I would post my observations on the center-of-gravity: After using a more-precise set-up to to check the CG, I found that I was a lot less tail-heavy than I first thought. The CG was only 0.7 mm further aft than the plans called for. I added about 1.8 oz. of ballast to the firewall (couldn't get the cowling off without tearing it up, so I used forecepts and installed the ballast through the cowling air inlets), and now, with my 310g battery, it balances perfectly. The image below is a scan from the instruction sheet, and I added the wing, MAC, and CG information to it. As it turns out, the recommended 85mm CG position is precisely at the 1/3 MAC position. Also, I discovered a little surprise: The Extra has a molded-in gas cap in front of the canopy that is exactly at the recommended CG point. That can be used as a reference point when you balance your airplane. On the illustration, the 9-inch lable marks the firewall face and it's distance from the CG - useful when you start calculating how much ballast you might need. And one last note: The bold 85mm marking on the instruction sheet is actually 142 mm in the scale of the drawing... so balance to what is says, not what it shows!
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Old Apr 15, 2012, 09:37 AM
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Two more flights on the Sbach, CG seems good

I got two more flights in breezy conditions yesterday. ~10 mph - but more or less up and down the runway, so landings weren't too difficult. Some gusting at altitude. Enough that you could feel a little 'bouncing' at times.

I did dial down my elevator on low rates a bit. The 100mm CG seems to be a very neutral CG point. Flying inverted needed only the slightest down elevator. I did a complete inverted circuit and it handled very well.

I can also report that the setup I'm flying (60A esc, SK4250-650kv, 4S 2200 30c lipo) has no trouble with a 10 mph wind.

After tightening up the landing gear, they seem to be working fine. No trouble taxing, taking off or landing on the grass field.
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