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Old Nov 02, 2012, 01:38 PM
Flying Hazard
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Quote:
Originally Posted by PeterVRC View Post
In those pics:
The slats (whatever they are) camber re-profile probably exceed what pitch down the flaps/flaperons add.
Switch them off and let's see what it does then.... LOL.
LOL, the slats increase the wing pitch momentum and add their effect to flaps, not the other way.
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Old Nov 02, 2012, 04:16 PM
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Got one of the SU-35 freewing jet, so far impressed with the materials and ease of putting it together. Like the fact that you don't need to glue the wings or rudders in place. Will be doing the final set up of the controls over the weekend. Will be using a Futaba 7c radio, I am not sure if there is way to get the TV set with the 7-channel radio. Does anyone know or can post a link to instructions for setting the TV for Futaba 7c radio for this jet? Hope to be able to do the first flight this Sunday.

Thank you

Henry Sharifian
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Old Nov 02, 2012, 05:08 PM
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For what it's worth. While trying to set up for thrust vetoring I lost power to receiver. It was suggested that the BEC in the ESC had stop working. Removing the red wirer from the thottle to receiver and adding a small nimh battery and all was well. To save weight deceided to put in a castlecreation 10 amp peak BEC. As soon as I plugged in the unit the cc bec sparked and smoked. Unplug immediately. Now one elevator servo not working, retracts not working gear door not working. Told my sad story to the fellows at our flying field and one said he was told that CC BEC will not work with some of these Chinese servos. I am still planning to get this plane flying. ( for what its worth)
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Old Nov 02, 2012, 05:59 PM
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Su, you read my post the 'opposite' way that it meant....

Flaps add negative moment - nose down. Slats add positive moment.
"The slats (whatever they are) camber re-profile probably exceed what pitch down the flaps/flaperons add."
That statement means... the slats effect of reprofiling the camber of the wing adds MORE positive moment than the flaps add negative. Thus the end result is the nose up attitude.
Not that I know that is what happens for sure, but it seems a likely reason.
The slats don't LOOK big enough to cause that much effect, but there can be other unseen resultants fo airflow redirection etc from them - so looks alone don't make something possible or impossible.

Much like was mentioned about down aileron/flapeon causing downwash over the elevator/s.
After I looked at the plane, about that, it is clearly going to be an issue.... down aileron/flaperon is going to 'blanket' the elevators into a dead zone... even if the aircraft can end up with positive AoA from inputs. The elevators are in the 'perfect' position to be affected by that!!!
F-22's have that issue (models anyway... and probably real ones too). But I would expect FBW can overcome ANY of such issues - to a very good, or total, degree - whereas model RC fliers can't do (monitor) all these factors when controlling a plane (like FBW can do perfectly). So if we move into such areas, we suffer and can't 'correct' it properly.

If the Su was set up with 'elevons' - ailerons move in unison with elevators - that issue would not occur then (it still will, but will be far less effect or issue, possibly negligible). The biggest issue comes if they operate 'against' each other - ailerons down, elevator up, (which what flaperons do) because this state is moving the elevators right into the peak area of aileron downwash.. Until the elevator has a large enough angle and 'clears' the peak downwash area some useful amount - which would be a lot of angle by then! So it possibly would never really be used to such an angle that it return to any area where it could get 100% effectiveness again.
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Old Nov 02, 2012, 06:13 PM
Throttle Bender
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Quote:
Originally Posted by R. Mike Neely View Post
For what it's worth. While trying to set up for thrust vetoring I lost power to receiver. It was suggested that the BEC in the ESC had stop working. Removing the red wirer from the thottle to receiver and adding a small nimh battery and all was well. To save weight deceided to put in a castlecreation 10 amp peak BEC. As soon as I plugged in the unit the cc bec sparked and smoked. Unplug immediately. Now one elevator servo not working, retracts not working gear door not working. Told my sad story to the fellows at our flying field and one said he was told that CC BEC will not work with some of these Chinese servos. I am still planning to get this plane flying. ( for what its worth)
Sounds like a reverse polarity issue. What kind of plug are you using from battery to ESCs? Is the CC10 wired with correct polarity?
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Old Nov 02, 2012, 06:18 PM
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Electronically this does not make sense.....

"CC BEC will not work with some of these Chinese servos"

A BEC (or battery even) is purely a voltage source. No 'timing', signal, digital/analogue etc etc involved at all. No type of servo should ever matter at all... except one that requires more current than the BEC can supply wiothout shutting down or frying! LOL

You already said the ESC BEC didn't work either, before the CC was tried.
This is the big clue.....
Something died during your TV setting up... probably a TV servo.... and that killed the ESC BEC, due to shorting or something. You would expect smoke, but is not a definite need to occur when something electronic 'dies', or is 'killed'. eg if it died 'quickly', before major current surge - which is what really fries things into smoke(!) - then you will not see any smoke, but it is still dead.

Then you plugged the CC BEC into a faulty circuit (servo failed possibility).... and in this case, the 'luck' of what unfolded was high current, frying, and thus sparks and/or smoke.

What to do......
Use a BATTERY to test the servos one by one. Watch the RX, or a servo tester, for power drop/cut (LED's going off, or fainter) and IMMEDIATELY disconnect if that occurs.
A battery won't fry like a BEC/ESC-BEC can.
The RX will not fry, because the issue is a short circuit from +ve to -Ve, not the signal line - and the pos and neg power only go to a rail on the RX connector and then out to the servos, so the path of the short circuit just goes into a RX pin, and then out another = not INTO the RX.
PS A "short circuit" does not necessairly mean a straight connection from pos to neg. "Short" means a circuit that takes a shorter PATH than it should if things are working normal. eg in a servo, if the drive transistor of the motor has some issue and IT shorts out, the circuit is still not straight pos to neg, it is just 'one component less' resistance down that path, and thus higher (possibly much higher) current and then a failure.
LOL, too many possible combinations to explain all in detail.... or how electronics all fully work.
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Old Nov 02, 2012, 07:11 PM
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My first thoughts was I has pos and neg reversed. I had made a jumper for the cc bec to be between the esc and battery. I have looked at that jumper a hundred time and beleive I hook everything up right???? All ready order new electric retracts. Sequencer from HK is backordered. I probably will not use a CC bec again on this plane. Please give me other choices
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Old Nov 02, 2012, 08:10 PM
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Quote:
Originally Posted by R. Mike Neely View Post
My first thoughts was I has pos and neg reversed. I had made a jumper for the cc bec to be between the esc and battery. I have looked at that jumper a hundred time and beleive I hook everything up right???? All ready order new electric retracts. Sequencer from HK is backordered. I probably will not use a CC bec again on this plane. Please give me other choices
Well Mike... the CC BEC is one of the most commonly used with this model for those who went with an external BEC. One of the reasons is its so simple.

So from what you describe you could easily do the same again with any other BEC.

If you could show a snap shot of your circuit we might be able to quickly see what may be the issue.

CC BECs Quoting CC:
  • 9. I fried my CC BEC by plugging in too much voltage and/or reversing polarity. Is it junk?
    No, never throw a Castle Creations product away! Send it in to us and for a flat rate repair fee we’ll repair or replace it. See our repair page for details.
BUT I don't think it was a polarity issue. I've reversed polaritied stuff before and it doesn't fry everything. May be just lucky but what did you set the voltage on the CC BEC to?

To fry the retracts you'd have to be over 6volts. I've reveresed polarity on those individually and they don't burn up. But the one time I stuck my TX lipo on thinking it was a 2S, it fried the sequencer and retracts.

My guess if you don't think the polarity was at issue, you may have set up the BEC or added voltage from something else to blow the servos.

Does the RX still work. Cause most of them will work up to about 8-9V.

And I'm sure the next time you'll just test it on via the RX on a single servo before lighting up the entire setup.
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Old Nov 02, 2012, 08:39 PM
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Set the voltage????? I believed this to be a plug and play unit. May go to hobby shop and buy another one, will ask them to set voltage to what? Wish I could sent picture, have equipment, not the skills to do it. Rx alright. Removed main retracts and plug directly into reciever, no worky.
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Old Nov 02, 2012, 09:33 PM
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Are you using the two male power plugs as they came on the plane? Or did you change to another battery connector? The twin male plugs are an accidental short waiting to happen.
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Old Nov 02, 2012, 09:37 PM
You are a "go" for reentry
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Wow Pete! Just Wow!


If you look at oodles of posted data (the sample is a slat though the SU has a dropped LE Device), these simple forms even at a higher AoA just increase lift while keeping the airflow efficient like a under cambered wing. Note they don't necessarily place the flaps at high angle avoiding them reaching stall. So your thoughts on what the Lift devices are doing are tangents because its not a flying wing as an isolated system. It has a stab around a 1/3 the area of the wings that holds the wing AoA in a high lift position. Very different from a habu.

Next.....Down wash is an effect that all aircraft experience even just by increasing the AoA without lift devices. Thus you see T tails and ... lots of different thing to keep some clean flow. SU's answer was they put the tailerons slightly lower than the wing so that it pitches up slightly the tailerons remain in sufficient flow. Many of the US designs keep the tailerons in line with the wing. You start seeing interesting base shapes around the bottom of the rudders to deal with some of the adverse wash etc but thats really all a tangent because its not a show stopper. So the tailerons aren't blanked as pitch devices from the ordeal. So no worries there.

The entire purpose of the stab is to set the angle of the wing. So while you are getting so focused on all the possible effects from the wing with lift devices extended, it is entirely irrelevant to so large a surface, the tailerons, that maintains authority of where the pilot directs.

Oh and everyone keeps going on about unstable and flight control systems. The SU-27 didn't have one till long after. The dynamics are basically the same so this is not magical computer stability control. So like I said, you keep over thinking it. ....

All this talk I wish I could have finished my finding. Its so nasty out I can only fly my nCPX in the living room.
Oh and I'm really trying not to argue. I'm just free writing in response to your comments where you might be getting a little mixed up.

Either way cheers Pete.

Quote:
Originally Posted by PeterVRC View Post
Su, you read my post the 'opposite' way that it meant....

Flaps add negative moment - nose down. Slats add positive moment.
"The slats (whatever they are) camber re-profile probably exceed what pitch down the flaps/flaperons add."
That statement means... the slats effect of reprofiling the camber of the wing adds MORE positive moment than the flaps add negative. Thus the end result is the nose up attitude.
Not that I know that is what happens for sure, but it seems a likely reason.
The slats don't LOOK big enough to cause that much effect, but there can be other unseen resultants fo airflow redirection etc from them - so looks alone don't make something possible or impossible.

Much like was mentioned about down aileron/flapeon causing downwash over the elevator/s.
After I looked at the plane, about that, it is clearly going to be an issue.... down aileron/flaperon is going to 'blanket' the elevators into a dead zone... even if the aircraft can end up with positive AoA from inputs. The elevators are in the 'perfect' position to be affected by that!!!
F-22's have that issue (models anyway... and probably real ones too). But I would expect FBW can overcome ANY of such issues - to a very good, or total, degree - whereas model RC fliers can't do (monitor) all these factors when controlling a plane (like FBW can do perfectly). So if we move into such areas, we suffer and can't 'correct' it properly.

If the Su was set up with 'elevons' - ailerons move in unison with elevators - that issue would not occur then (it still will, but will be far less effect or issue, possibly negligible). The biggest issue comes if they operate 'against' each other - ailerons down, elevator up, (which what flaperons do) because this state is moving the elevators right into the peak area of aileron downwash.. Until the elevator has a large enough angle and 'clears' the peak downwash area some useful amount - which would be a lot of angle by then! So it possibly would never really be used to such an angle that it return to any area where it could get 100% effectiveness again.
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Old Nov 02, 2012, 09:49 PM
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Merlinfan: I agree, accident waiting to happen. For that reason I was very careful. Jumper was female to female and female to male with CC bec inbetween
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Old Nov 02, 2012, 09:49 PM
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Quote:
Originally Posted by R. Mike Neely View Post
For what it's worth. While trying to set up for thrust vetoring I lost power to receiver. It was suggested that the BEC in the ESC had stop working. Removing the red wirer from the thottle to receiver and adding a small nimh battery and all was well. To save weight deceided to put in a castlecreation 10 amp peak BEC. As soon as I plugged in the unit the cc bec sparked and smoked. Unplug immediately. Now one elevator servo not working, retracts not working gear door not working. Told my sad story to the fellows at our flying field and one said he was told that CC BEC will not work with some of these Chinese servos. I am still planning to get this plane flying. ( for what its worth)
Very similar to my situation after blowing the stock ESC BEC. I guess this warrants another look through at all the stock wiring. I took it for granted that rat nest was good to go from the factory.
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Old Nov 02, 2012, 09:58 PM
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Quote:
Originally Posted by Maxthrottle View Post
Oh and everyone keeps going on about unstable and flight control systems. The SU-27 didn't have one till long after. The dynamics are basically the same so this is not magical computer stability control. So like I said, you keep over thinking it.
The Su-27 was designed from the start to incorporate fly-by-wire. In fact, the 2nd T-10 prototype crashed because of a FBW failure.

From www.globalsecurity.org:
At the initial stage, the Design Bureau produced a great number of alternative configuration concepts, including the one based on a conventional solution, with an integral body, modelled on the F-15; but interestingly enough, it was ae new concept of airframe configuration that the subsequent design efforts were based upon. Another important feature of the new fighter was to be implementation of the concept of longitudinal static instability, with balancing achieved through use of an electronic distance control system (EDCS). Introduction of this innovation promised a substantial decrease in losses for balancing and a dramatic improvement in the plane's manoeuvrability in dogfighting.
...
From the very beginning of designing, the Su-27 developed as a fighter-interceptor without any capability of operating against ground targets. The American F-15 Eagle fighter was taken as the starting point - a "rival." Its data were put into a computer and played through in competition with Sukhoi's initial design model, which obtained the ratio of 1.35:1. In accordance with the adopted concept, Sukhoi began building the T-10 aircraft. This was the first "unstable" fly-by-wire aircraft in the Soviet Union. In Western terminology, this is an aircraft with aerodynamics determined by the parameters of the control system, or an aircraft with electronic stability. The American F-16 was the first such aircraft. An ogival wing with a blunt strake and deformation of the middle surface were included in the integrated aerodynamic design developed jointly by the aerodynamics department of the Sukhoi OKB and the Central Aero-Hydrodynamics Institute.
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Old Nov 02, 2012, 10:06 PM
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PeterVRC: I wish I had the knowledge to understand everything you tried to explain, but that does not stop me from saying Thank you for trying.
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