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Old Aug 16, 2009, 12:06 AM
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Tweaker
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Corona Del Mar
Joined Sep 2005
9,145 Posts
For your viewing pleasure, I present my Sukhoi v2.0! 2-Cell Conversion

To see this power system installed in an E-flite Beast UMX biplane, see my mod here; http://www.rcgroups.com/forums/showp...postcount=2482

For a more tame 1-Cell version, see my build post here; http://www.rcgroups.com/forums/showp...&postcount=957

I will be updating this post whenever I make changes or additions to this setup as I go.

My Current Setup Components;
TX - JR X9303
Motor - AP03 3000Kv 5.6g from RotorFever.com
ESC - 7A 1-2Cell with 5v BEC, 2g from Rotorfever.com
Voltage Dropping Diode (to drop the BEC's 5v to a safe 4.2v for the Rx Brick) - 1N4001 from RadioShack
12.2g Battery - 2x Zippy 240ma 20C (14min flight)from HobbyKing.com
13.7g Battery - 2x Hyperion G3 240ma 25C (14min flight) from AlleRC.com
8.1g Battery - 2x Hyperion G3 120ma 25C (5-6min flight) from AlleRC.com
Prop - GWS 5030 or 4540 from gwsprops.com
Prop Adapter - GWS 1.5mm rubber Spinner/Adapter from gwsprops.com

Remember, you will need to use the TX to change modes on the RX's motor port from it's stock "brushed" output to now "Brushless ESC" mode. See the instructions in the photos below...

Goals, take the Sukhoi to it's max.
1 - Crazy power (has 110g thrust) AP05 3000kv from RotorFever.com
2 - Add 2nd aileron servo to allow for flaperon mixes.
3 - Allow use of current single cell batteries.
4 - Add switchable lighting, they are just too cool!
6 - Use all 6 channels of the AR6400, why not?


It's all in there and the airframe weighs about 6g more than my 1 cell version, (of course when you add the two 240ma packs the total AUW is almost 50g).

I knew that the weight would be higher but with approx 2:1 thrust it's no problem on the vertical. Tip stalling seems to be the curse of the Sukhoi as the weight goes up. To handle the increased wingloading, I mixed the ailerons so they can be dropped as flaps to compensate and tame the landings and low speed flying. I've tested this on everything from sailplanes to jets and ail-as-flaps is a great way to go, without the need for discrete flaps. But ALWAYS test their effect UP HIGH because the results, especially with jets, can suprise you. Once trimmed out they are simply awesome, and the main reason I spend as much on a transmitter as I can afford, mixing is great fun and really can improve a models flight performance.

Mixes;
1 - Flaperons with elevator for super tight loops.
2 - Ail to Rudder coupling at low throttle when the ail-as-flaps are down to retain control and cancel adverse yaw that occurs in this mode. (edit, tested and this works really well and is required with full flaps.
3 - Elevator compensation, down elevator comes in with flaps to retain correct attitude.
4 - Differential aileron, they drop less than the raise, again, to cancel any adverse yaw. (edit, flight tested, not really needed)

Battery Chamber,
I made a similar "Bayonette" battery holder as my v1.0 Sukhoi conversion but with an added deep "Chamber" pocket to hold the first battery in a fixed position pretty much on the C/G. The second battery slides on top of the first (like bullets in a gun clip) and is adjustable fore and aft to allow easy C/G adjustments. No Velcro, no ballast, no balance connectors, and I can use all my single cells as needed in my other planes. I prefer the 240ma packs as I want at least 10 minute flight times with enough extra for a go around or two..

ESC,
The 7A ESC with 5v BEC (2 Cell Version, from Rotorfever.com) when re-wired weighs only 2g and gives a solid power system with some extra load margin. I added a diode in the red wire to the AR6400 to drop the BEC output voltage down to 4.2v which is the maximum safe voltage for the rx brick. I ran the red and black to the AR6400 power leads and only the white wire to the AR6400 motor port's PPM output connection. I did find that the TX throttle travel needs to be set for 125% to get full throttle and reliable arming from the ESC.

Lighting,
Tiny Brite lites simply ROCK, amazing workmanship. This 0.9g set is plug-and-play. I plugged them into the Ch5 Port (that's the 4 pin port so you need to pay attention) and use a tx switch to control them. They can have sequencing of the landing light and strobe if your radio can handle it, I just used a Tx switched channel for On/Off. When ON, the red, green, and nose landing lites go on solid and the tail strobe flashes. I ran the wires thru the wing and in slits inside the aileron hinge gaps. a tiny bit of HobbyLite filler and they are invisible!

This is a good start, hopefully I'll maiden it in the morning.

Regarding adhesives, I use tiny dabs of low temp hot glue to mount the brick, servos, and tac wireing like the lites. Just be sure and watch out for the tiny glue thread that comes off of the glue joint as the gun pulls away and get rid of it (these tiny threads can stall a servo, ask me how I know...) I use 30min epoxy for most all structural stuff because it really penetrates and flows which allows you time to position and remove excess before it flashes off. I never use 5min as it gets brittle over time, sometime discolors, and doesn't seem to penetrate as well before flashing, so I've stopped using it.

Edit 8-16-09
Flight Report! It flippen flies like a bat out of Hell!

Conditions, overcast light winds 0-2 variable direction, temp 68. Small school yard and basketball court with low altitude obstacles everywhere.

I fired it up with 2 Hyperion 3G 25C packs, taxied out and took off at about 1/3 throttle, raised the nose, rolled on the throttle to full, and it accellerated vertical! Trimmed like a normal Sukhoi minor clicks of ail and elevator as needed.

I cruised around at 1/3 to 1/2 throttle, sounds slightly like a gasser so I think the GWS 5030 needs better balancing. The ailerons are way sensitive even with expo as I changed the geometry with my new linkages, they have a ton of throw so I re-adjusted the D/R and Expo. It's probably better to document the surface deflection used now as the setup is non stock.

I removed the differential aileron mix as it turns out not to be needed.

Rudder and knife edge? How about knife edge loops? I'm rusty at this plus I've got to get over the "first flight after long build" jitters but it has so much power that I kept getting into KE and adding power and up and over it goes into a KE loop!

Flaps! With the added weight this is the single most important add-on. If you do go to 2 cells I'd highly recommend that you add the 2nd servo aileron mod with flaperon mixing (after stripping out the old linkage, it's only an extra 1g and some new linkage work ). I put the mix on the left side lever of the TX so I can slide the flaps up and down as needed. There is 15% down elevator compensation that rolls on with the flaps so the plane simply slows down with flaps down without climbing or diving. I have the rudder mix in at 100% of the aileron stick movement when the throttle is below 30%. So what does this do? At 100% the plane slows to a crawl and requires about 1/4 throttle to fly level, the roll control (with with the rudder mixed) is slow but very controllable. An example, if you drop flaps fully down and give full right aileron, the left aileron will stay down, the right aileron will raise to about neutral. The drag from that full length left flap normally would actually cause the plane to pull left (adverse yaw) instead of rolling right. The ail-to-rudder mix cancels the yaw and allows the roll, restoring normal control. So, with full flaps it just floats in like a cub trainer, awesome. Tip stalling doesn't seem to be a problem, the plane comes in very tame and with some power on it's very cool. I found that it was great to pull flaps in and out depending on what I was doing, 1/4 to 1/2 flaps for low and slow school yard bird buzzing, full flaps in a vertical dive as air brakes. The flight envelope is huge, from pylon fast to very slow, endless possibilities!

Runtime? I flew the packs to LVC at about 14min, I programmed the ESC for soft shutdown and at LVC the motor just idled down unexpectedly at about 20ft, I dumped in flaps and the plane went slo-mo into the grass field and endo'd, not a scratch. I set the ESC for hard brake and the prop will stop in a stall but spins most other times with the throttle cut. The scarry thing is that the motor doesn't want to restart at low throttle sometimes! I came gliding in low and slow over the basketball court, maybe 6ft, and was going to rotate and punch out vertically but the motor stuttered and I had to land (barely pulled that off). I was carefull to keep an idle going when low and slow. Edit, I experimented more with power off gliding, the prop spins even with hard brake. When you re-apply power the prop actually stops spinning and then re-starts, like it was spinning backwards... So I find that if it doesn't re-start I have to cycle the throttle quickly to get it going. I'm now flying on a 10 min timer with good vertical performance up to the alarm and still have two more minutes to wrap it up and land.

Batteries, I tried both the Hyperion 3G 240ma 25C's and the HC 240ma 20C's, two flights on each type. The Hyperions have noticeably more punch but not night and day, both types flew the plane well for over 10 minutes. The two HC's are 1.5g lighter but I really didn't notice that either in the flight performance.

Lights? They were visible even in daylight, can't wait to try this at dusk. Too many obsticles here for night flight

Props, So far I'm using a GWS 5030. I laser tached it several times and it spins at 11,450 with Hyp 240ma G3's 25C and 11,427 with HC 240ma 20C.

So that's it for now, I got four flights end on end for almost 50 minutes straight, the batteries, ESC and Motor were barely warm to the touch. I'm a very happy nerd indeed

EDIT 8/17/2009
I dug in tonight and took a "real" watt meter and soldered up proper adapters and made up a solid test bench to measure these setups and post some performance data;

RotorFever AP03 5.5g 3000Kv Outrunner
Two Hyperion 240ma 3G 25C Batteries
GWS 5030 Prop
100% throttle - 3.3A - 23W - 7.0v- 11,450rpm - 33mph
75% throttle - 1.3A - 10W - 7.6v
50% throttle - .52A - 4W - 7.8v

GWS 4540 Prop
100% throttle - 3.2A - 22W - 7.1v- 11,228rpm - 43mph
75% throttle - 2.1A - 15W - 7.4v
50% throttle - 1.3A - 10W - 7.7v
25% throttle - .67A - 5W - 7.9v

I've always wondered about the GWS rubber spinner/adapter and it's ability to stay on the shaft with some real power on it. Well, I'm glad I've been doing my measurements from behind the motor. The 5030 prop shot off and got my full attention! Maybe I should use a bit of CA or rubber cement when assembling?

This gave me the opportunity to test the 4540 prop and I was suprised to see how close the WOT rpms were. I held the plane vertical and still think it pulls hard so I'm looking forward to flight testing it as I think the Sukhoi likes a 4" pitch speed. If the vertical holds, this will be a winner I think.

These measurements seem to indicate that the motor is a tad beyond it's max current spec so throttle management should be used at WOT. I felt the motor right after the bursts and it's warm for sure.

EDIT 8/18/2009
Test flew the 4540 prop early this morning, it's hard to see a tiny white plane in a full overcast! This prop gives the plane a bit faster speed, still goes straight up very well. There is more torque roll (and I can't hover to save myself but the power is there). I was taking off at 1/3 throttle and 20-30% flaps nice and gentle. Shot some landings with full flaps, takes some practice as it has so much drag that you can shoot very steep approaches right to the deck, flare, it will land and come to a stop in about 10 feet. It looses energy so fast, you need to carry some power all the way in. Flight times are still over 10 min.

EDIT 8/30/2009
I flew both V1 and V2 this morning, clear and blue skys, 80 degrees. I tried the headcam to get comparitive flights and had the angle too low so got a lot of ground shots...

There really isn't much of a comparison, the two cell simply has such huge power and speed over the V1 and can pull vertical and accellerate at will. Both are fun to fly but they are quite different. I will get the 1 cell motor/prop comparisons done as soon as the prop adapters arrive. It will be nice to get as much out of a 1 cell setup as possible, every gram of thrust is needed.

I discovered some alarming things about the tail feathers. The steering on V2 was squirrly on taxi and during a high speed pass I almost stuffed it and 30-40mph as it didn't want to pull up. I checked all the horns and found that the lower rudder hinge was torn and that the elevator horn was completely loose!

I hinge taped both sides of the lower rudder and used a thin film of 30min epoxy around both sides of the rudder and elevator horns. I did this on both planes.

Beware!

Edit 9-6-2009
After flying it more, I found that the motor had some accidental down thrust. With this much power (it easily flys at 1/4 to 1/3 throttle), when I would punch the throttle it would dive. I pulled the motor and shimmed the mount for zero-zero thrust, this is important.

Next , I weighed out the trim schemes and went with light weight press-on decals from Vigilante-RC.com . I stripped off the old decals and sanded the wings and fuse with 600 grit to remove all the tiny mold bumps. The decals were easy to apply! The V2 is now BLUE...

Edit 9/7/09, last day of summer...
Flew the plane today, winds measured at gusts to 8mph, the plane penetrates like a bullet but still gets knocked around a LOT! I walked out onto the school yard lawn and dropped into the grass which was wet. It appears that the VigilanteRC decals may not be waterproof as they got a smudge here and there with a few water drops... need a light mist of clear sealer I think.

I think the thrust line repairs helped, I may step the prop pitch down to 5030 to slow it down a bit and double up the static thrust for better close in flying. That's still over 30mph.

Edit 9/20/2009
I flew my V2 today with a 5030 prop, it really was a pleasure. The lower pitch is better for all around flying and the 2 cells still spool it up (11,400rpm). I love using a little flaps and cruising low and slow, rotate and roll on the throttle to rocket straight up. I've now wired up some HYP 120ma 25C packs and look forward to trying a lighter weight V2, but I do like the current long run times on the 240's. I also tried to program the 7A ESC from the Tx to turn off the brake to improve the in-flight restarts when the throttle is chopped in a spin etc. Well, this ESC would program with a programmer before install but now it won't go into program mode in the plane... This is an older 7A 2Cell ESC, not the newer 1-2Cell v2.1 version so that may be the issue. I cobbled an adapter and used the programmer to turn the brake off now.

I was looking over the plane after flying and noticed that the stab had some wrinkles next to the fuse where the stab must be flexing in flight since it hasn't been hit (yet). I made a paper thin stiffener from a piece of 0.2mm (.008") C/F sheet and slid it thru the fuse on the underside of the stab. Then a drop of foam safe CA and covered with some white trim. Very stout now, hopefully this will contribute to more solid tracking at high speed.

I swapped all of my connectors yet again (hopefully the last time) to these new HC .8mm gold pins. They have very good tension and feel so solid, plus they are cheap!

Edit 11-16-2009
I had a question on what my Tx settings were. I've added a printout of my X9303 Transmitter settings from the JR PC Data Transfer Interface (from Horizon Hobbies approx $49). I can also send the actual data files that can be uploaded to another X9303.


Here's a little tour

Parkzone Sukhoi v2, 2-Cell Brushless, Flaperons, and Lights! (2 min 17 sec)



Flight Video; Here's my first attempt at using a FlyCam headset, now THAT's a fashion statement that any passer by will comment on! I walked down the street and flew one flight all the way to LVC, about 14 min on two of the HC 240ma 20C's. I did a bunch of mixed flying, takeoffs and landings. Wind was about 1-2 from the left.

Parkzone Sukhoi v2.0, Flight Video, 2cell Brushless, Flaperons, 6ch with Lites. (9 min 41 sec)


If you are curious about headcams?, here's the FlyCam setup; http://www.rcgroups.com/forums/show...&postcount=3118



For a more gentle modification, see my 1 cell "V1" Sukhoi build here;
http://www.rcgroups.com/forums/showp...&postcount=957
RemE is online now Find More Posts by RemE
Last edited by RemE; Nov 26, 2010 at 07:20 PM.
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