Freewing Su-35 Twin 70mm 12 blade

[C17loadmaster]

Are you using each stab and aileron on their own channel? If you did a good amount of trimming on your last flight and didn’t look at the control surfaces, at least they counter one another. Just a thought..,

Radio system are you using? I’ve had issue with some receivers and especially gyros in this plane. Also, the control horns become soft after a while due to the way they mount. I tightened mine further than necessary, then epoxied them in. Basically making them permanently part of the control surface

[Sam CS]

Need help or advise;
I replaced original FW stab servos with these KST DS215MG. Last time i was out flying, the model was trimmed, that was about 2 weeks ago. I went out this morning and noticed that my left stab was out of trim. Radio hasn't been touched and i could have bumped the stab while moving it, but on power-on it should have came back to it's fixed position.. Also, servos are buzzing on and off. Right stab seem to be okay.
Is it normal for a servo to get out of trim?
What would cause the servo to get out of trim (not including radio TX)?
Another thing too, take a look at the pics, notice the aileron trim - this is my level flight trim. Is this normal? IMO its a bit excessive.. don't you think?

[C17loadmaster]

Once you get it worked out and get to start seeing what the plane can do it will all be worth it. Nothing flys like the SU.

[Sam CS]

I was planning on gaining some altitude and diving down under 45* or so without any thrust to see if i still get the roll effect. After that is done, go into level flight and throttle up to 100%, by doing so i should get an idea if TV needs trimming. I never done this before so it's only theory at this point. Hoping to get this accomplished this weekend.

[xviper]

You know, with TV nozzles, I'd check those first before suspecting the ailerons. Even if the nozzles are just a little unequal, you can get a slight roll, even at low speed. The more thrust that goes through them, the more affect on roll and yaw.

[Sam CS]

Copy that C17LM, I agree, too many factors to consider. I'll start with stabs and move to TVs.
Its definitely going to be a project to get this thing trimmed right.

[C17loadmaster]

Also, there are a bit more possibilities to cause this plane to not fly straight compared to others. 1. Is the nozzle alignment 2. Motors/ESCs not calibrated together 3. The lower fins out of alignment (I call them strakes, like on the C-17) 4. The wings can be secured uneven due to the round brace in a square hole. 5. Standard control surface trim and alignment.

After a while the wing braces can gain play in them causing them to chatter when taxiing and in flight. I wrapped the circular wing insert with metal ducting tape to eliminate the noise and slop and in the wings from causing issues in flight.

[Sam CS]

Thank you guys for the suggestions, looks like rotary knob is what i will do.
S.

[TangoVector]

Disclaimer: I'm quite new to OpenTX but this is the way I would try to do it and it should be relatively easy. Add the left rotary knob S1 in the INPUT, with maybe 20% weight. MIX for both CH4 & 5.

INPUT
name TRIM
Source S1
Weight 20%

MIX
Add on ch4 and 5
name trim
Source TRIM (actually there will be a I: and a number prior to TRIM)
Make sure one of the channels are set to -100% for different travel.

I don't have my OpenTX computer with me, so there is no testing being done, but it "should" work. Once you are happy with it you can make the necessary hardware changes and remove the rotary knob from everything. Test on ground first

[xviper]

Anybody flying this thing on OpenTX?
Cant figure out how to trim stabs in-flight independently. Example: my horizontal stabs set to ch4 and ch5. Aircraft banks left, im almost positive its due to stabs being out of trim. Is there a way to setup trims to ch4 & 5 and trim it in-flight?
I used ail trim to achieve level flight but ail not the problem.
Any thoughts?

The best way is to manually trim them via rod length on the ground, but to do it in flight, you'd have to have mess with servo sub-trim while flying, which could be somewhat dangerous. I suppose you could also put one of them on the rotary knob (assign to one of the channels) and mix it so you can adjust during flight and then use elevator trim to adjust the whole thing if it needs it. But then, this would have its hazards as well in that the next time you fly it after flying something else, the rotary may have been moved.
Personally, unless you're talking about a huge amount of AIL trim to correct this, I'd eyeball the elevators as best you can and just leave it.

[Sam CS]

Anybody flying this thing on OpenTX?
Cant figure out how to trim stabs in-flight independently. Example: my horizontal stabs set to ch4 and ch5. Aircraft banks left, im almost positive its due to stabs being out of trim. Is there a way to setup trims to ch4 & 5 and trim it in-flight?
I used ail trim to achieve level flight but ail not the problem.
Any thoughts?

[xviper]

Yeah, I guess. My SU-35 is my second one. My current F/A-18 V1 is my third one, but none of the crashes were due to failed anything except my first SU, which melted the Dean's connectors. The rest were dumb thumbs or gopher dirt mounds when landing. I just kept buying them till I figured out how to fly them.

[Sam CS]

Don't get me wrong X, i just want to see better quality gear installed on critical components (like stabs for example) on a $400.00 model... that's all.
From what i red on multiple forums the fail rate is high.

I guess if we don't wreck them, we wont buy them... right lol? ;)

[xviper]

I'm guessing I've had a couple dozen (probably more) Freewing and FMS planes over the years and I only recall out of all those, 2 servos gave me cause to change them out. I think they cost the manufacturers maybe 5 bucks each but they seem to work just fine. If they suddenly put in $30.00 servos just to appease a few "critical" owners, we'd see an increase, on average of $100.00 per plane. I doubt I'd have purchased nearly as many planes as I have. They are getting more and more expensive now due to better quality of fit and finish and detail. I can't afford a lot of the ones that really appeal to me. Add another 100 bucks and you can strike off several more.

[C17loadmaster]

They definitely aren’t top notch, but they’re not complete garbage. I’ve read about them a lot, especially for the F-14, and they still work fine. I don’t think there is anyway you will tell the difference in flight, but I had the same perspective as you do when I first got them. Some models need to have their servos swapped out immediately IMHO. The F-86’s ailerons and flaps are plastic geared with large control surfaces. The flaps have gone out on mine plenty of times from any type of pressure applied to them.

I did swap out the control rods and connectors to ball link from the F-15. I added small washer on the outside of the ball link side, and fuel tube on the white retainer to prevent a disconnection in flight. The standard snap on plastic connectors and S bend rods are in the box of spare parts

[Sam CS]

I just dont understand why they sell a pricy model with cheap ass servos.
I wouldn't mind paying $30 per servo as long as it fixes the problem.
I had same issue on 70mm f16v2... seems like freewing going cheap on servos 😞

[C17loadmaster]

***I just re-read your comment and apparently I missed that you were looking for digital

I have currently have 3, and have totaled another 2. They all have the sloppy elevators, and all the other flight controls as well. You can see the slop more on the full flying stab.
I replaced them on the F-14 and it made it a bit better using the same linkage and connections. They were Hitec HS-85MG. They are the same size as the SU-35. They do feel and sound much than stock, and they won’t break the bank. They have the standard version as well for $10 cheaper.


https://www.towerhobbies.com/cgi-bin...SABEgJEoPD_BwE

[Sam CS]

Hey guys, need help on digital metal gear servos for horizontal stabilizers. Someone recommended these (TGY-306G) however, they are discontinued.
What would be a good replacement? I got a lot of play in the stock servo arms on both sides as well as control rod. All together the free play is about 5mm or more.... looking to tighten that gap a little.
I already found a good replacement for the control rod, but need help with getting the right servos.
Any advise or suggestions for a servo replacement? In addition, my first SU had the same issue, 2 out of 2 having same problem... what are the odds?

[Marktur]

Hey guys, quick update...LOVE THIS JET! Flying with 6000mAh HRDs, landing at 3.5 minutes with 35%+ left...they have only been cycled about 5 times so I'm sure I can extend the time over the next month. I love the way she floats! Very forgiving on landing, and plenty of power - not endless vertical, but not feeling the need to upgrade anything. I haven't been doing any 3d stuff... lots of compliments at the field, however.

I had a hard landing on the 3rd flight, the front gear broke...fixed it, broke again, this time we just poured a ton of Gorilla glue and sprayed a bit of water, and the whole thing is now much stronger than the rest of the jet! Hasn't been a problem now in over 20 flights.

I'm running CG at the spot in the picture above - the wire channel for the ailerons. (Thanks seaviper). With the CG further back, it got weird and unstable. I actually glued a few bolts inside the nosecone for a bit more weight up front, and push the battery as far forward as it can go.

My only issue with this jet (and I know I just need to fly it more and adjust a bit..) is that the elevators are very sensitive when inverted - really wants to balloon very easily - so I can't seem to do a nice 4-point or slow roll...not sure why it acts one way normal and different inverted, or the "right" way to fix it - hate just throwing in more expo blindly. Ideas?

[C17loadmaster]

In addition, I used a bent landing gear strut that I repaired enough to allow the spring action to function properly. I cut off as much of the shock’s tube and compression piston that I could, used a grinder and sand paper to smooth out the sharp areas, and mounted it to act as a shock absorber for the brace. When the gear is extended, there is no open space between the two. The two of those modifications reduced the amount of contact area that the fuselage would be under a lot of stress. I have not had any problems since then.