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Old Feb 05, 2013, 10:46 AM
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Originally Posted by Maxthrottle View Post
You need to redo that video. You have the CG position wrong. We've posted this and illustrated it several different ways. But the easiest marker is the aileron wires pass through box where the wing joins the fuse. Its understood to be an easy physical reference for CG155.


While you trim as you go along, the 10mm stab setting is for aft CG and the 13mm is forward CG.

The Rudder Hinge seam is expected to crack and move freely. And its not just the rudder hinge but all the hinges need to be checked and glued down if they appear loose.

6S batteries depending on the weight class; if they were lighter batteries they moved forward, if they were in the 750g+ they move back. Several like myself have them are the very back of the tray.

Landing Gear you really should always test dunlops pointing down. Gear is more like to jam against gravity if there is any issue, rather than gravity doing half the work. The sound you're hearing is actually got me wondering. The gear has a switch that cuts the cycle out. When you hear them pulse a second or so after the cycle is the cutout rather than the buttom switch. Double check that the nose gear actually makes it to the end lock point unobstructed.

Bullets slipping off They are sprung bullets. If they get slightly loose from bending them into the female socket, pry them apart slightly to get it back to a taught connections. Tape just isn't practical. If you are talking the banana style.... their rolled cage can also be pried slightly to also get a snug connection.
Yeah re-doing it now-- damn I read it wrong!! Anyway I re-measured, and seems odd-- my batts weigh 440g each =880g, I CANNOT get CG at 145-155mm, with batts all way to nose-- I can only reach CG at 160mm!!! Whats going on!????
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Old Feb 05, 2013, 10:54 AM
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Yeah re-doing it now-- damn I read it wrong!! Anyway I re-measured, and seems odd-- my batts weigh 880g, I CANNOT get CG at 145-155mm, with batts all way to nose-- I can only reach CG at 160mm!!! Whats going on!????
my batts weigh 880g!!! WOW thats alot
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Old Feb 05, 2013, 11:41 AM
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my batts weigh 880g!!! WOW thats alot
440g each =880g total, yeah still heavy
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Old Feb 05, 2013, 11:49 AM
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In your case this is true because you have 2x 153g motors in CS housings so you have a little tail weight. But you likely have something else in there that's making it a challenge. I have the same battery weight in my 5800 and that's mid-aft of the tray. But you also have that servo in the pilot head nose that should need you to move the batteries back.

This is kind of why you leave battery position commentary out of it. Me I have the working OLS and camera along with balsa panels, Satellite RX and steering servo further forward. Its all very little over all weight but its positioned enough forward to have to move the battery weight back along with my ESC's since my EDF setup is only a few grams more than factory.

So it varies depending on what ever goodies a pilot adds. But you added L bar Al. That should be plenty so double check why yours is so heavy in the bum.

Quote:
Originally Posted by IntheTubeDeep View Post
Yeah re-doing it now-- damn I read it wrong!! Anyway I re-measured, and seems odd-- my batts weigh 880g, I CANNOT get CG at 145-155mm, with batts all way to nose-- I can only reach CG at 160mm!!! Whats going on!????
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Old Feb 05, 2013, 12:01 PM
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440g each =880g total, yeah still heavy
Heavy??? a little but not way out there. There are several in use in that weight range.

"The Zippy 5000 40C(200 amps) 834g V8Truckin Maiden and Flight Vid

The Zippy 5800 30C (174 amps) 838g is great for long flight times as long as the pilot isn't WOT the entire flight.

The Genisis 5500 55C(302.5 amps) at 886g. Way more amps than necessary for the application.

The GenAce 5500 25C (137.5amps) 890g heavy without much amp/hr cap improvement.

The Nano-Tech 6000 25C (150 amps) at 908g tips the scales and still has a rep."

The question is, "is that weight giving you some kind of performance advantage?" You can see the 2W25 a 2720kv motor with a CS70/12 in the video just posted. The watts were low, amps high so the thrust is so so. You have the 3180kv motor which will increase the amps even higher to gain thrust and run redline doing it. So the battery weight and running hot is the concern for 4S considering the end result of less than 1:1.

But its the same concern I have for the 8S set ups and is why the guys were concerned for my examination of the 2040kv leopard and recommended the 1840 etc to keep amps down and battery weight more useful.

Either way.... get out there and fly the thing
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Old Feb 05, 2013, 12:09 PM
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Originally Posted by Maxthrottle View Post
In your case this is true because you have 2x 153g motors in CS housings so you have a little tail weight. But you likely have something else in there that's making it a challenge. I have the same battery weight in my 5800 and that's mid-aft of the tray. But you also have that servo in the pilot head nose that should need you to move the batteries back.

This is kind of why you leave battery position commentary out of it. Me I have the working OLS and camera along with balsa panels, Satellite RX and steering servo further forward. Its all very little over all weight but its positioned enough forward to have to move the battery weight back along with my ESC's since my EDF setup is only a few grams more than factory.

So it varies depending on what ever goodies a pilot adds. But you added L bar Al. That should be plenty so double check why yours is so heavy in the bum.
You'd think so, but my added weight in mods is forward of CG!! Pilot mod added servo, Airbrake added Servo and push rod, nothing added aft of CG!! Its crazy! Logic would say I'm gonna be NOSE HEAVY... its opposite!
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Old Feb 05, 2013, 12:31 PM
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never said it wasn't. You just have to have something that is explain-ably causing it.
I posted the fulcrum formula's earlier in the thread. I don't know if you added anything around the stab servos, rudder install etc but as you add weight further out in places, they have greater leverage.

Regardless the CG position is the CG position. If you need to move that much weight forward, it still means something is causing the counter force aft.
Unless you're in another universe where the laws of physics are a little different

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You'd think so, but my added weight in mods is forward of CG!! Pilot mod added servo, Airbrake added Servo and push rod, nothing added aft of CG!! Its crazy! Logic would say I'm gonna be NOSE HEAVY... its opposite!
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Old Feb 05, 2013, 01:23 PM
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never said it wasn't. You just have to have something that is explain-ably causing it.
I posted the fulcrum formula's earlier in the thread. I don't know if you added anything around the stab servos, rudder install etc but as you add weight further out in places, they have greater leverage.

Regardless the CG position is the CG position. If you need to move that much weight forward, it still means something is causing the counter force aft.
Unless you're in another universe where the laws of physics are a little different
Could be the 'ocean pull'... I don't know, I triple checked I have NOTHING added rear or center of plane, I'll have one more look...
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Old Feb 05, 2013, 02:38 PM
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Originally Posted by Maxthrottle View Post
never said it wasn't. You just have to have something that is explain-ably causing it.
I posted the fulcrum formula's earlier in the thread. I don't know if you added anything around the stab servos, rudder install etc but as you add weight further out in places, they have greater leverage.

Regardless the CG position is the CG position. If you need to move that much weight forward, it still means something is causing the counter force aft.
Unless you're in another universe where the laws of physics are a little different
Ok even with batts ALL way forward against retract bay I can get CG at 155mm, but its close, 160-165mm is easier and gives me a little play in batts, do you think flying at 160mm or even 165mm is airworthy?
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Old Feb 05, 2013, 02:43 PM
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Originally Posted by Maxthrottle View Post
never said it wasn't. You just have to have something that is explain-ably causing it.
I posted the fulcrum formula's earlier in the thread. I don't know if you added anything around the stab servos, rudder install etc but as you add weight further out in places, they have greater leverage.

Regardless the CG position is the CG position. If you need to move that much weight forward, it still means something is causing the counter force aft.
Unless you're in another universe where the laws of physics are a little different
Ohh, maybe an afterthought-- from ESCs to motors I used 10AWG, should I have used 12AWG? Those 6 10AWG wires are heavy ...
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Old Feb 05, 2013, 03:54 PM
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Su35 Pilots don't forget the basics before you fly this beauty, double check everything!! Triple check! Measure Twice, Cut ONCE its the old saying, applies to Pre-flight also! And thanks you guys for setting me straight on the CG origin point--live and learn!

Freewing Su-35 Pre-Maiden Check List (0 min 0 sec)
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Old Feb 05, 2013, 03:55 PM
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Ok even with batts ALL way forward against retract bay I can get CG at 155mm, but its close, 160-165mm is easier and gives me a little play in batts, do you think flying at 160mm or even 165mm is airworthy?
I have no idea of your setup or skills; so I can't answer that. It wasn't problematic but then you could still just being measuring it incorrectly. Post a pic cause it shouldn't be that hard.

Just read your next post??? why so high on the motor side. Yes that will add plenty in the tail and this being a Y only sees partial loading. Its why the gauge on the motor wires are always less. The battery is supplying the full load and is the side that needs the heavy gauge.

Man I thought I was heavy with 12 gauge. Stock is 14 so... ya heavy in the tail
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Old Feb 05, 2013, 04:10 PM
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Originally Posted by IntheTubeDeep View Post
Ok even with batts ALL way forward against retract bay I can get CG at 155mm, but its close, 160-165mm is easier and gives me a little play in batts, do you think flying at 160mm or even 165mm is airworthy?
Then the engine weight is more than stated, Did you use epoxy to glue in the foam around the housing?

Did you add ANYTHING to the rear? different servos? ESC maybe?

How about the batteries, are they really 440 grams? Thats allot of weight for one battery. 3s? 3s x5000? What brand of battery are you using?

How about battery weight, the entire length. is it heavier on one side vs the other? Is the metal plate in the front of the battery? where the battery connects to esc?
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Old Feb 05, 2013, 04:12 PM
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You should probably cg with canopy on as well. All the canpoy weight if forward of cg.
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Old Feb 05, 2013, 04:36 PM
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ITTD, I don't recall seeing it along the way in your layout but.....

If you use dual batteries in parallel, you should use an "X" in the wiring so they are then "pooled" before heading to each ESC.
Basically two "Y"s....
Two leads to the battery side..... two leads to the ESC side.... on big joint of the two "Y"s together.
There will still only be two connectors used.... which only need to be the size required to carry the current (Amps) of one motor side, as each battery is still just feeding its 'one motor worth' to the "X" point anyway.

Not wire it as just one battery per ESC.

So I am not sure which way you did it, but have the "X" way!

This assures the voltage to both ESC's is identical, and also that one side can't go flat/LVC - due to its battery - before the other side. Plus equalises load over both batteries. And also means if one battery does drop a cell or something, there is still good power to both motors anyway.
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