Westbender

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I'd like to hear from owners of the Sig Sukhoi.

1. What engine/prop combination are you using?
2. What type of servos/linkages?
3. How did the assembly process go for you?
4. How do you like the flight performance?
5. What is your overall opinion of this arf?


Thanks for your input!

Vince

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I have one on order, should be here by the end of the week. I will be putting a Fox 2.4 on it. Servos will be Hitec 5645's with 4-40 ball linkage. I will post the results and impressions of the plane when and as I assemble it.

Vince

433rd

1. What engine/prop combination are you using? Saito 2.70 Twin, 20X10 prop. Incredible power, pulls the plane vertical (as well as any other direction) great! You will need to cut the firewall back 1" if you choose the Saito twin. My second choice for glow was a Moki 2.10 or gas a BME 44 or 50.
2. What type of servos/linkages? Hitec Digital's (on everything but throttle)
3. How did the assembly process go for you? Great, no surprises, good fit, the colors grow on you. It turns out better than what it looks like on the box.
4. How do you like the flight performance? Excellent! Even at 15 pounds with the heavy engine and glow driver system, it lands like a trainer and flies as good as just about anything else in my hanger.
5. What is your overall opinion of this arf? Two thumbs up! Tons of room in the fuse, excellent main gear design, excellent flying plane, built light, the cowl could hide a small block Chevy in it with room to spare and the control surfaces are Huge. Excellent covering job (with readily available replacement covering if needed (UltraCote cream and green)) and if you order from Chief Aircraft (they have a great special price on it right now) or Quantum models you get Free shipping!

The only drawback at all I found was the way the tail feathers are attached. I would recommend beefing up that area if you plan on putting the plane through the "ropes". I also replaced most of the hardware with Rocket City stuff.

It truly is an incredible plane.

433rd

Westbender

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I suppose I can post my own info...

1. BME 50 with 21X10 Mejzlik. I think I'm going to have to go to a 22X10 though. I'm turning about 7400-7500 right out of the box with this prop. I'd like to absorb some more of that power and convert it to thrust. However it'll still go vertical forever at half throttle. <BG>

2. Hitec 605MG's, a 5945MG Digital on the rudder, 4-40 rods with ball-links, aluminum servo arms and Sullivan steel control horns. Zero slop...

3. I've built a number of Sig arf's, so I've really got the hang of it. I use a Great Planes electric hinge slotter with two sets of blades installed to open up the hinge slots. It's quick and makes for a perfect fit for the double-X hinges. I also make my own dihedral brace out of hard ply for the wing. Every Sig arf I've seen has a sloppy fitting piece of pine (I think) for the brace. I like to make sure the top and bottom edge of the brace fits well against the spars. Except for a couple pieces of triangle here and there, the rest is stock.

4. I don't have a lot of flights on it yet, but I like what I've seen so far. Very solid and stable. I have some trimming to do for sure. I have the CG still at the recommended starting point. It takes a fair amount of down elevator when inverted, but moving the CG back should take care of that. The only other thing I have to work out is the pitch coupling in knife-edge. It really tucks to the belly. I'm going to try reflexing the ailerons up a little. If that doesn't help, I'll have to resort to mixing it out with the radio (JR 8103).

5. So far I've had a good experience. Easy, quick assembly. No nasty tendencies in the air. Seems like a real solid airplane. I'll know more after some more stick-time though.

Robotech

My Feedback: (9)

1. What engine/prop combination are you using?

Zenoa G62 / Zinger pro 20X10 TME Simple smoke system with 16 Oz. smoke tank. Bennet smoke muffler. Gobs of thick white smoke!

2. What type of servos/linkages?

Hitec 615MG All the way around. Two (pull-pull) on rudder. Rudder and 2 elevator servos mounted in the tail The 4 heavy 615MG servos in the tail helped balance out the weight of the G62. I only added about 4 oz. of tail weight. This was after I tripled the firewall and tri-stocked everything up front. I used standard 4-40 linkeages and horns with metal clevises and Dubro 4-40 servo arms.

3. How did the assembly process go for you?

I would rate it a 7 out of a possible 10. Fit wasn't too good in some areas. Tail section was weak but it wasn't that difficult to improve the weak spots. The Canopy was a kind of weird setup and mine blew off on the second flight. I replaced it with a canopy from a SIG Extra. I think it makes it look a little sleeker. (See pic)

4. How do you like the flight performance?

Excellent even at 16 lbs it handles nimbly. Landings are slow and steady. No tendencies to tip stall. With the G62 pulling it it has NO limits.

5. What is your overall opinion of this arf?

I love it. It's big enough to see but not a monster. As you can see from the replies so far you have a wide range of engine choices. No bad flying habits. The manual was clear and easy to understand. The quality of the materials were good but you'll throw out the included hardware like with most ARFs. The best thing is that it's not an EXTRACAPGILESLASEREDGE.

Vince

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Here is one of the web sites I found while doing some research on this ARF. It show the installation of an ZDZ40.

http://www.concentric.net/~Dhmodels/workshop7.html

Geeze, a G62, no kidding!!!!

Vince

Robotech

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YUP :stupid:

Westbender

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Thanks for the input! Hopefully we'll get more posts in this thread.

I saw a post this morning in the "Big Sig Su31" thread about a wing failure yesterday. Maybe we'll get some more info on that. I'd like to know exactly where and why the failure occurred. I wonder what the post-mortem turned up.

epc

My Feedback: (33)

Engine :

3w 42 i Menz S 20x10 prop & pitts muffler.

Servos :

JR 8411 on Rudder
JR 4721 on ailerons
JR 8231 on elevators
Futaba 148 on throthle.

JR 1400 6v batt.

Rocket city horns on elevator and ailerons and Dubro large scale horn on rudder.

Assembly :

-Reinforced the tail section mounting plate with 1/4 balsa.
-Fiberglassed the wing center section
-The elevator ribs seem too fragile
-Reinforced the firewall
-Moved the tank to the c.g.
-The wheels included in the kit are garbage


Flight Performance :

Very good and 3d capable , lands very easy.

Overall performance :

Very good flier .
Kit can be better .
Too fragile.
Good fiberglass cowl
Strong gear.
3d capable with huge control surfaces.

VoughtF4U

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This is all in my review, but I'll add my stats here too.

1. What engine/prop combination are you using?
FPE 3.2 with a Zinger Pro 22x10. Great combo on this plane. No firewall standoffs were needed, and all the vertical you would ever need. Engine still idles slow enough to allow the plane to slow down for landing.

2. What type of servos/linkages?
I am using Hitec 5945 digital on ailerons and elevators and 5735 digital on the rudder. Way overkill but I had them so I used them. Pushrods are a homemade 4-40 threaded rod and carbon piber pushrod mix.

3. How did the assembly process go for you?
Still went pretty fast for me even with pulling all the covering off and putting carbon fiber tape on the wings. Re-covering it took longer than assmebling did. No gotchas except for mounting the tail. I added wood and CA'd some fiberglass cloth in to hold the tail together.

4. How do you like the flight performance?
I really like it and it gets better with every flight. I am getting smoother and more precise, yet really starting to get wild with it at the same time. As good or better at most things than the rest of the Edges, Caps, and Extras out there. But then again everyone has their own ideas of what is better, it is all a trade off, some are better at one thing but worse at others. The Sukhoi is agood blend of everything.

5. What is your overall opinion of this arf?
Not a big ARF fan and probably will not buy any more ARFs, but all-in-all I like it. No major complaints. I would rather see more ARCs though.

-Scott-

Westbender

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Have any of you guys experienced pitch coupling during knife-edge? If so, how did you trim it out? Mine pitches to the belly pretty good. I want to try reflexing the ailerons a little and see if it helps. Otherwise I'll have to mix it out with the radio.

epc

My Feedback: (33)

You can mix it with the radio but when it is just a litle compensation necessary I do it mannually.

How much coupling you'll need depends on your c.g and wing dhiedral.

Westbender

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Well, I want to move the CG back further. That's only going to make the "pitch to belly" worse. I'm certainly not going to change dihedral at this point. Besides, dihedral changes affects roll coupling, not pitch coupling. It's going to have to be aileron reflexing or radio mixing. In the few flights I've got on it, I've been flying the compensation, buts it requires quite a bit of elevator input and I can't seem to transition to knife-edge smoothly at all. Not a pretty site. lol It's not a drastic problem, but enough to make me want to try and trim at least some of the coupling out.

Westbender

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Well I flew today and worked on trimming. It seems the pitch coupling I experienced in knife-edge flight wasn't just happening in knife-edge. When I would yaw the airplane in either direction, it would pitch down. I'm curious to hear if anyone else has encountered this type of coupling with the Sukhoi. I know my airframe is dead on straight. My incidences are perfectly matched between wing and stab. My vertical stabilizer is exactly at 90 degrees to the stab. There's nothing more I could have done during assembly. I ended up mixing up elevator with rudder and after a few flights of adjustments on the mix amount, I've got the coupling pretty much neutralized. I first had the mix assigned to a switch, but after quite a few take offs with the mix turned on, I determined that the rudder-elevator mix on take offs wasn't causing any problems at all. I disabled the mix switch and now have the mixing on all the time. It feels really good transitioning into and out of knife-edge now. The next thing I want to do is get some more time on it and then start slowly moving the CG back. By the way, the BME 50 is running better and better with each tank. It's starting to smooth out now on the low end. What a power-house! Yeehaa!

VoughtF4U

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Mine has pretty good pitch coupling also, although I haven't really noticed it anywhere but knife edge. Are you using JR or Futaba? How much mix are you using to dampen it out? If I can get some windless days here I can start experimenting a little better with mixing, but for now, it is too windy to do any type of trimming or adjusting.

Westbender

My Feedback: (1)

It's a bit breezy here too, but the coupling was severe enough that I really wanted to do something about it. I have a JR 8103 radio. I can't remember the exact amount of mix I ended up with, but I think it's somewhere between 25% and 30%. It's actually quite a bit, but it flies way better now. I'm sure I'll have to fine tune it on the first calm day we get out here.

If you don't mind doing a little test, next time you're flying your Sukhoi (before adding this mix), try yawing with rudder input while flying level and see if yours pitches down as well. It's not a severe out of control pitch, but certainly was enough to surprise me a little. Make sure you have some altitude. <grin>

By the way, once I added the mixing for the pitch coupling, I didn't notice any roll coupling at all. The plane feels way more neutral now.

Vince

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You guys that are talking about coupling, did any of you check the stab incidence relative to the wing? Just curious.

Vince

VoughtF4U

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I got to do one flight last night before it got dark. I didn't add any mix yet. I checked the coupling from straight and level flight at various speeds. I found that aat higher speeds the coupling showed up right away with rudder input. It wasn't real bad, but noticable. Nothing I would normally mix out. At medium speeds it was much less noticable. At low speeds it would show up some, but it was very noticable when you added rudder one way and then went to rudder the other way. It would really show up with the second rudder input. Still nothing real bad, but I will try adding in some mix and see how it flies.

As far as my stab incidence goes, it is right on with an old Robart incidence meter. Not saying it is perfect or anything, but with the equipment I have it is as good as it is going to get.

I have started to bump my high rates up and I am progressively moving my CG back. It is really starting to grove now and I am really starting to be able to let loose with this thing. Couple od more flights and I should have it about where I want it.

Westbender

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VoughtF4U,

Sounds like I may have had this coupling a bit worse than you. Mine would pitch down at all speeds on rudder input. I went flying again last night as well to get some more stick time. The mix I added really helped. It doesn't exhibit that coupling no matter how or when I use the rudder now. This thing really has some rudder authority doesn't it? <BG>


Vince,

Here's a bit of one of my pior posts above regarding incidence: "I know my airframe is dead on straight. My incidences are perfectly matched between wing and stab. My vertical stabilizer is exactly at 90 degrees to the stab. There's nothing more I could have done during assembly."

Does your Sukhoi shown this coupling as well? I would assume since VoughtF4U's and mine both have it, that it might be the "nature of the beast".



All,

I have noticed a new problem. I tried doing a "wall" last night and when I pulled back on high-rate elevator, the plane rolled-out severely. My elevators are matched perfectly as far as position and throw. (Although I'm going to re-check them again) I need to do some more testing to see if it rolls out in the same or opposite direction when attempting the same thing from inverted flight. I have a feeling it's a wing shape problem in that the two wing haves are not exactly the same or maybe one of them is slightly twisted. (I did check for twist when I was setting up incidence before the ailerons were installed) My take on it at this point is that the right wing is stalling much quicker at extreme angles of attack. The funny thing is, the plane does not tip-stall when I do my normal stall tests. This only happens when I have a little more forward velocity and I crank on the elevators. Once I rule out elevator adjustments and wing twist, I'll experiment with small pieces of triangle stock taped to the leading edge of the left wing. I should be able to equalize the high-alpha stall that way by adjusting the amount of triangle stock there.

Has anyone experienced this tendency?

VoughtF4U

My Feedback: (1)

Westbender,

I have only done three walls with mine so far, two were botched up and one was perfect. I attribute the first two mess ups to not having the rest of the controls centered when I started the pull on the elevators. One rolled out left, one right. The thrid one I made sure I was straight and level with no control input and then pulled hard, wham, straight up no problems. I'll do some more testing this weekend with it.

Mine doesn't tip stall as long as I keep the aileron movement to a minimal. Otherwise it will slide off and drop the left wing a bit, but nothing drastic or uncontrollable.

Westbender

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Hmmm... I'll certainly be testing further as well before I make any changes to it. I'll keep what you say in mind about making sure all other controls are at neutral the next time I try it.

Thanks for the info. I'll keep you posted on how things progress.

Vince

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I am still in the construction phase, that is why I was asking. I will let you know when I fly it.

Thanks for the input
Vince

BAS

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Robotec just wondering did you ever move your cg back a little to correct the inverted flight of your sig suk. I flew mine yesterday and have the cg at 27% also and had to give some down elevator also to keep it level i am just afraid of getting it to sqiurly and having elevator to quick if i move cg back . Just curious if you ever moved it back. Thanks

p39

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This is the third summer on my Sig Sukhoi. Fox 2.4 Pro Zinger 20x10. Assembly was great. HiTec 645 servos on elevators and ailerons. B&B Smoke pump. Abell smoke muffler. I've been toying with the idea of a 3.2 Fox.... as it isn't much heavier than the 2.4.... But right now she slows so great on landing. It'll do anything I ask of it if my fingers allow.

BAS

My Feedback: (28)

I have about 20 flights now on mine with the Fox 3.2 running a NX 22/8 and it flies great with this combo but i do have a NX 21/8 ordered. It flies just a little fast at this point and i thought the 21/8 would slow it down a little. Vertical is unlimited at 3/4 throttle , and i have the cg at 4/75 back on fuse sides. I really am getting use to the plane still but i really like the way it flies, like its on rails. I think it lands very docile for this type of bird also. I had a few construction issues , but nothing major. I did drill and tap the wing bolts for 1/4 20 Nylon bolts because the stock ones didnt line up with the blind nuts. I did also reenforce the tail end a little and course the firewall area. Other than that its a nice keeper.