Twin 70mm SU47 360 Thrust Vectoring - Page 54 - RC Groups
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Sep 09, 2010, 11:25 AM
Jet Foamy addict

What do you think of getting a much stronger set of motors, like the 2500kv from RC-Castle???

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Sep 09, 2010, 03:13 PM
Fly, crash, fix, repeat
f4addict's Avatar
I think the stock motors have enough juice for this bird. Unless you want to go rocket speed, but then dont forget the weak 9gm servo's. Instead i'd suggest shaving off some weight from this plane, use a lighter 3300mah lipo. But everyone flies differently so far, higher speed from this plane makes me worry about one thing. Wings flexing and breaking. but if you have reinforced adequately then sure, you can install the motors.
Sep 09, 2010, 03:22 PM
Registered User
hklagges's Avatar
I think f4addict's advice is very good. The plane is hard to handle and fast. Of course you can power it up (if you reinforce the wings etc), but it will be even harder to fly.

Sep 24, 2010, 09:48 AM
Fly, crash, fix, repeat
f4addict's Avatar
hi all,
did anyone try just to fly from tailerons? and use the ailerons as flaps? i just thought of it, now the next step i am thinking is to mix the canards with the tailerons.
But i want a second opinion before i open this fruggly up once again.

Any flight reports??? comon guys this is one of the most ''different'' planes seen on field. some one must've flown it!
Sep 24, 2010, 09:56 AM
Flying Hazard
SU-4ever's Avatar
Do not use only the tailerons for rolling.

Remember the lever law: Force*distance = Momentum

The Tailerons are too much close to the rotation axis so they are not efficient, I once built a FSW pusher jet without ailerons and it took a whole lot of taileron deflection to make the airplane roll just a bit, that means lots of drag, lose of speed and poor maneuverability.

Sep 24, 2010, 04:57 PM
Fly, crash, fix, repeat
f4addict's Avatar
yes you are completely right, but at the same time, i am using hi torque mg's for elevators, and am planning to add the tv nozzles back again. dont you think that with the tv's and elevators it would make the roll rate easier? on one hand i agree with you with the equation but on second hand, there is a little green man inside me who's telling me ''do it'' do it..jk, i guess you are right though, i dont think this bird's going to take any more of my bashing.
Sep 24, 2010, 08:51 PM
Registered User
Mtn_Commando's Avatar
Originally Posted by f4addict
yes you are completely right, but at the same time, i am using hi torque mg's for elevators, and am planning to add the tv nozzles back again. dont you think that with the tv's and elevators it would make the roll rate easier? on one hand i agree with you with the equation but on second hand, there is a little green man inside me who's telling me ''do it'' do it..jk, i guess you are right though, i dont think this bird's going to take any more of my bashing.
even the TV nozzles are too close to the axis of rotation to be effective. and even with TV combined with tailerons (elevons), you'll still have very little roll authority during approaches, when both airspeed and fan efflux are low.
Sep 25, 2010, 06:25 AM
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hklagges's Avatar
Originally Posted by f4addict
Any flight reports??? comon guys this is one of the most ''different'' planes seen on field. some one must've flown it!
Currently I am migging (LX MiG29) around if I fly at all... no time whatsoever.

Sep 25, 2010, 06:54 AM
Registered User
hklagges's Avatar

Ailerons as flaps

Originally Posted by f4addict
and use the ailerons as flaps?
I did this via programming (ailerons as ailerons and flaps, with some negative elevator mixed in when using them as flaps). I couldn't perceive any effect during landing approach, but that may have been due to lack of experience.

Oct 03, 2010, 09:12 AM
Registered User


As I haven't received my Mig-29 yet, I'm still Sukhoing around...

I followed this thread for a long time and would like to give back some...

I have everything stock, ARF version, battery is a 6S3700mAh DesirePower.
CoG is - as mentioned earlier in this thread - 10mm aft from what is mentioned in the manual.
Flighttime is 04:00min, draining the battery to 30-40%, depending on flight-style.
The throws I reduced to around 60% by DualRate - increasing to 100% pending...
Drag-Chute is disabled - enabling is pending...

We have a 30mx3m runway here, surrounded by lawn.
Takeoff-roll is just enough, but one needs to "rip" it off the runway by just the right amount of elevator. I think that if the nosegear could be positioned just 5mm lower, to give a higher AoA during ground-roll, it'll lift-off way nicer.
For LandingRoll, I need about three-quarter of what we have, without the drag-chute.

My personal impressions and my personal opinions:
I have now twelve successful flights on the counter and have to admit, she's quite a hand-full when in the air. What's different is the behaviour at stall. Instead of falling onto the nose or rolling over a wing, she'll gently sits on her ass. Which makes it quite dificult on approach, not to come in too hot in fear of stall, but also not to "fall" into vertical with the tailcones about knee-height above ground...
And I *wish* I would've had the patience to do the kit instead of the ARF. Being able to decouple the TV's from everything else is a must, especially when you need to get to know the plane. As I wrote earlier, I need to take her off the runway somewhat determined. While I have full Power on. Which makes the TV's quite effective. Which makes the nose showing me where the sky is - very high. Which then makes me compensate with a nose-down input. While still having full Power on since I'm still in process to take-off. Which still leaves the TV's in high efficiency. Which then makes the nose pointing out to me, where the plane shouldn't go - the ground...
So the Throttle acts like an analog-switch for the dual-rate of all functions...

Otherwise, if you get accustomed to that - I did now after twelve flights - she's got *great* looks in air, and has a comfortable and quite low engine-sound. And I can't stop listening to that air flowing and hissing around her, above the whine of her engines when I approach low and do a military-turn quite close to me... Her size and looks make her literally scream out for attention, at least to everyone on our fields around here in switzerland...
She travels nicely with something between a third and half-throttle, but has enough power to go 60 to 70 endlessly. Flat-spins and tight loops are a breeze, once you got your nerves around. I am now thinking about increasing the DualRates to 100% for aerobatics.
Landings are still faster than I'd wish, but routine and gained confidence reduced the "ass-pucker-factor" a lot and I'm now looking forward to enable the drag-chute. I did unplug that servo for safety-purpose, but since I am now able to plant the plane repetitevly within 5m, I'm looking forward to something that'll slow the plane down after touchdown...

And this movie clearly shows that the landing-gear holds it's promises...
(disclaimer though: on that flight I had to squeeze 06mins out of the battery for a pedestrian to clear the approach-path, the following first approach was a bolter, and on this second I didn't want to risk the plane by another go-around. Nowadays, I know that just a very small input for nose down fully recovers her controls once she's started to stall, which would've avoided the Cobra-landing...)

Pitot-Tube - or whatever that antenna on the nose-cowl is - has been removed for good...
Installed between flight 10 and 11, removed when unpacking the plane from my car for flight 11...
It's installation was suspect to me from the beginning, and to my opinion, that thing'll never hold if installed as advertised...
I'm thinking of drilling a hole on the back of that piece of plastic, to get a piano-wire in place, which would then pierce into the nose-cowl, so it has a firm large surface to stick into.

Greetings, Dany
Last edited by Danyboy; Oct 03, 2010 at 09:42 AM.
Oct 03, 2010, 11:00 AM
Registered User
anthodenn's Avatar
Great reveiw Danyboy. It's still good so see more flight footage of this very beautiful jet!

With the givin cg revision and flight characteristics, do you think you should change it back to the cg as the manual instructs or at least 5mm aft? I'm interested because Im putting the kit version (no electronics) together right now BUT Im making it into a pusher (prop). I don't want my plane standing on its tail when comming in for a landing.
Oct 03, 2010, 01:20 PM
Registered User
In all honesty:
I don't know.

Going forward with the CG might improve stability, might even make it go over the wing or even on the nose upon stall instead of sitting on its tail...
But then again, that needs to be proven.
The "behaviour" I mentioned is because of flying too slow and stalling it. Changing that behaviour does not change the fact that the planes stalls. If you are unable to fly the plane fast, you'd better not fly the plane at all... But I'd say that's not the topic here, but I hope my point has been made understandable.

People have flown CoG according the manual up until 10mm farther backwards, and I'd consider that a safe range to start from.

Further information: To install the battery, I did not have to cut or glue or do anything to the fuse. All that was needed is a "plate" that I cut from styrofoam, same crosssection as the battery, and a depth of about 12mm, which sits at the end of the battery compartment. As the Pusher-Prop does influence the aerodynamics some, I would recommend to aim for and start-out with the (safe) factory settings and adjust from there as deemed needed...

Cheers, Daniel
Oct 03, 2010, 03:27 PM
Registered User
hklagges's Avatar
Hello & Gruezi Daniel,

tx for the flight report, which sounds very realistic - the Su-47 is a harsh mistress! One thing I'd like to know, please: How heavy is your plane (AUW, i.e. "with everything"), please?

I wonder how effective a gyro would be if it is just stabilizing horizontal (= elevator) axis.

I also wonder, given how stressy the plane is e.g. due to high landing speed, how to build it with a focus on minimum weight:
  • Fixed canards (with a slight up angle).
  • ESCs mounted forward of the fans, not behind them
  • Light (4mm) gauge wire to the front where the battery sits
  • No carbon spars in the wings (really?)
  • Possibly no retracts, phew
  • Only a very light battery.

All the points given above don't sound exciting at all...

Oct 04, 2010, 07:11 AM
Registered User

I do not think, that the handling would "improve" - I'd rather use the term "change" - by making her any lighter...

Mind you, the Su-47 is the first plane with forward-swept wings that has made it to official marketing-status, not only drawing-board or even experimental...
That's not just because "we" now have the materials and technologies to manufacture such a wing, it's mainly - in my opinion - that we have electronics that are enough advanced and fast to control such a monster of aerodynamics. And even then, it's not just gyros, it's an advanced flight-stabilisation system that controls based on different inputs like airspeed, AoA, Attitude, Thrust-setting, etc. Almost impossible to replicate in such a small model...

In my opinion, it is not the problem, that she's not stable. The "problem" is, that she's having a different handling outside of what would be considered a normal flight envelope, of what we're used to, and which appears to be an "not-normal" if you think you are flying an aft-swept wing.

And then again, that's what makes her special: She *is* special. Which means she's non-normal...

Making her lighter will not make her act differently, she will only act later in terms of stalling her... Which might even enforce her handling qualities: She will sit on her tail somewhat later/slower, but she might do it much more pronounced, as with less weight but the same airframe, the air has to do less work to achieve the same as when she's heavier...
And the flighttime of 4mins equals 2600mAh used... Using a smaller battery would definitely overtax those, except if you use the heavy-duty ones, which are heavier again...
Using a heavier battery might be interesting? Though that definitily calls for a bigger airfield than I have, to have the gear surviving...

And for god's sake do not remove the gear...!
My impression is, that as soon you extend the gear, she's way more stable on the roll-axis, especially when going slow...

Additionally, I personally refrain from using gyros on planes.
Reason being, that the can have some interesting intelligence, which will work out fine when in normal flight-envelope, but it might bite you in the ass when going outside... And if I do wander outside into the uncharted territories, I do not want to have to switch something off that made flying easier before and to which I'm used. And if I get into troubles, I'm already stressed out, and will most likely *not* have the abilities to think about flicking a certain switch...
I am *not* saying gyros are bad!!!
I'm just saying that for me, personally, and for no one else per-se, it works out best, if I manually correct the flaws of the machine and keep the machinery as simpel as possible. I'm simply too dumb when under stress to handle twenty switches...
And that way, I eliminate possibilities for surprises in the future, when routine made me forget about those possibilities.
Especially in a plane that is made to do aerobatics.
If it's more something like a F-14 that more like cruising around, then it's a whole different story...

Will weight her this afternoon and report the figures...

Cheers, Daniel
Oct 04, 2010, 08:30 AM
Pointy end at the front.
benjo's Avatar
Danyboy! could you land your Su-47 any slower next time! good save, nice one!

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