YA Sukhoi...Maiden Flight......Finally
 

well, just wanted to share my experience with this beautiful ARF.

Kit : Yellow Aircraft Sukhoi 120 size
Engine : YS 140 L with Slimline Pitts style muffler,
Zinger 16x12 Prop, Dubro Soft Mount,
Tetra 25 oz Fuel Tank & OS "F" Type Glow Plug
Fuel : Wildcat YS 20/20
Radio : JR 8103 TX & S PCM RX
Servos : 2 Hitecs Digital 5925's on elevator
1 JR Digital 8411 on Rudder
2 JR Digital 8321 on Ailerons
1 JR 537 on Throttle
Batteries: 2 1650 NIMH batteries from Radicalrc.com

OK, first let me say that I bought this ARF and engine from a very nice fellow modeler here on RCU. I always liked the looks of the Sukhoi, so I had to have one, and this one looked to be the perfect size since I didn't had to go gas.
Right upon opening the box you can appreciate the high quality these kits are made with. Everything was packed perfectly. I laid everything out on the bench to make a quick check if everything was there. It was.
After looking and reading thru the very nicely explained manual I started building as per instructions. Everything seemed to fit nicely, except the cowl didn't line up perfectly. Nothing I can do about, so I just kept on building.
When mounting the cowl to the fuse I found that the indicated method to use looked to weak, so I ask a couple of questions here on RCU and modified the cowling fix as described in this thread by Jim:

http://www.rcuniverse.com/showthread...ghlight=sukhoi

I also found out that the wing mounting needed improvement and threw out the nylon bolts and installed metal bolts with corresponding blindnuts after beefing up the support with more plywood.
When installing the servos, I also didn't like the idea of using long push-rods on the elevator, so I tail mounted the servos, and used Hangar 9 Titanium 4/40 linkages as well as on the ailerons.
After everything was installed and checked twice, it was time for balancing (as per manual 4 1/2" ), and surprise surprise we needed 30 oz. of lead in the nose. I guess that was the sacrifice for tail mounting the servos and using the heavy wing-bolts.
Throws on the control surfaces where set as manual, and those where my low rates. High rates where set 30% more.
I used no Y harness or servo reverser of any kind. Everything is setup with mixing in the radio.
OK, now it was time to break in the engine. OH NO :eek: why is this engine wobbling/shaking so bad :confused: Something had to be done, so I threw out the the very expensive Hydemount and mounted a Dubro Soft Mount. After another evening of swapping everything out and re balancing the plane, I went out Saturday to the field to try to break in the engine again. Hmmm...after adjusting the high end, the engine was purrrrrring along, and not nearly shaking or wobbling as bad as with the Hydemount. I ran about one gallon of fuel thru it, and everything seemed to be perfect in order to attempt a maiden flight on Sunday morning.
Well, I got up and weather looked good so off to the field I went. Fueled her up, range check OK. Taxing out to the runway went OK, but I think the springs need to be more tighten on the tail wheel for better response. Nothing to worry about now, and I will take care of it later. Oh boy, my knees where shaking like crazy. To late, here we go :eek: Throttle up and taking off. Roll out and lift off where nice with no surprises. I flew her around in circles a couples of times, and 2 clicks of right aileron trim was all she needed. No elevator trim correction what so ever. I guess my balancing was right on the money. I noticed immediately that she was touchy on the elevator and did not like much elevator input (snaps out if given to much). I corrected this issue by the second flight with dialing 60% expo in on elevator. No more problems. Rolls where a little slow for my taste, so I switched to high rates, and they where OK. So my high rates on ailerons are now my low rates, and new high rates where dialed in. Landing approach looked OK, and surprisingly she flew very nice even at low speed but doesn't like to get to much rudder input when slow. Final approach was at a moderate speed, and once you cut the Throttle she slows down very quick. Touch down was pretty easy. Maiden flight completed, and all I could say was Perrrrrfect ! :D
I flew her a couple more times yesterday, and this one is definitely a keeper. I don't think that she will be very 3D capable, but will make a very nice aerobatic airplane. Just have to get used to her.
If you are planning of buying a Sukhoi, I would not hesitate to go and get a Yellow Aircraft one. Trust me, you will not be disappointed..

YA Sukhoi...Maiden Flight......Finally
 

May I suggest your plane needs to go on a diet? With 30 ounces in the nose my guess is you are over 13.5#. My YS140L with Slimline Pitts muffler provides unlimited vertical on my H9 Cap 232 with an APC 17X8 prop at 12.5 pounds w/o fuel. You may want to rethink your dual elevator setup and twin battery packs to reduce weight. A good single forward mounted servo can drive the elevators. The trick is to get straight runs from the servo arm to the control horns through two Dave Brown pushrods. Or try two servos forward mounted through two pushrods. This should eliminate a lot of nose ballast.

The 16X12 prop is intended for pattern style planes....much different from your 25% aerobat's performance needs. Try more diameter and less pitch...

Joe

Congrats!
 

Well congrats on the maiden... I hope you love this plane!

The tail-mounted servos are the weight culprit. With three Yellow 120-sized planes, I've never had a problem with the standard pushrods supplied for the elevator.

Otherwise, it sounds like a bang-up job! Congrats Texas!

YA Sukhoi...Maiden Flight......Finally
 

Congrats- Texas,

My Sukhoi maiden flight was on Monday of last week and she pretty much behaved like yours did. My set-up is pretty much like jsonin except I used the Saito 170R for power.

YA Sukhoi...Maiden Flight......Finally
 

Thanks for the input everybody. I really love that Sukhoi.

I think I will leave the tail mounted servos in for now, since this plane will not be used (as for now) for wild 3D flying anyway. This is what my profiles and other 3D planes are for. I have not weight her yet, so I am not sure how much it is. My guess is at about 13-14 lbs. If I remove the tail servos, I will have some nasty holes back there, but I might consider it later. Let's wait and see how she performs once I get used to her and try to throw her around a little.

I bought already a Scimitar 17x8 prop (I am just a fan of wooden props) and will try this prop next weekend. Let's see if she likes it better. If not I will go 17x8 APC

Juhan and Equest, what was your final weight on the Sukhoi ?

YA Sukhoi...Maiden Flight......Finally
 

Texas 3D,

My Sukhoi weighed in at 13.5 pounds, approximately.