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Old Feb 07, 2013, 01:26 PM
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Old Feb 07, 2013, 01:28 PM
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Tucked away, I posted it a few times for those modding stuff. You add a bigger servo, battery, hinge, chute, etc depending on where you put it, you need some counter weight. Get carried away like a heavy EDF and Motor, you start needing more battery or more mods in the nose to counter it.
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Originally Posted by DamonH View Post
Mass X distance = Force.
What that works out to is
Mass X Distance From CG = Distance From CG X Mass

So if you put 10g 50cm in the tail that's about 7 oz of torque force that otherwise didn't exist.

LOL...I knew you had that little formula tucked away somewhere...
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Old Feb 07, 2013, 01:42 PM
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Quote:
Originally Posted by IntheTubeDeep View Post
My added mods would seem the logical answer but it appears my weight issue is in the tail, its tail heavy even with 900g of batts almost all the way forward in tray!! And ll my mods are forward of CG so I dont think mods are the problem, if they were I would be NOSE heavy 100% Besides all the mods add up to about to:

Cables (1 Y, 1 reg): 11g
Pilot servo: 7g
Airbrake servo: 17g
airbrake pushrod: 2g
Batt tray alum.: 2 @ 23g=46g
epoxy guessing: 60g
Nose Cone Mod 8 min mags: 3.4g

TOTAL=147g

So total of ALL mods is about 147g that not much!! I'm still almost 1000g heavy...but where? looking now...

OK, Alright...............

What is the weight of your mods, vs OEM equipment????

I'll bet that your fans and motors are heavier than OEM, and at a far aft location, that weight is multiplied by the length from the CG.

What exactly do your fans and motors weigh (combined total)???????????

Regards, Dave


P.S. You know how a seesaw works, don't you????????
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Old Feb 07, 2013, 02:34 PM
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Quote:
Originally Posted by v8truckin View Post
What was the weight of your motors, being so far back from the cg the added weight of the motors and wires may be a heavy point.

Also regardless of tailheavy you still don't want to be 1100g heavier.
Quote:
Originally Posted by davemilw07 View Post
OK, Alright...............

What is the weight of your mods, vs OEM equipment????

I'll bet that your fans and motors are heavier than OEM, and at a far aft location, that weight is multiplied by the length from the CG.

What exactly do your fans and motors weigh (combined total)???????????

Regards, Dave


P.S. You know how a seesaw works, don't you????????
exactly why I said what I did earlier. Ya mods are in the nose but most of the mods in the nose are close to the cg, so they really don't have the effect on cg as greatly as the motors being so far away from the cg. Exactly like you said a seesaw. 150g 20cm from the cg point isn't the same as 150g 110cm from cg.
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Old Feb 07, 2013, 02:38 PM
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I guess you could allways buy a second SU35 and use the first one for a display model.
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Old Feb 07, 2013, 02:58 PM
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That information has been posted. The motors he's using is 153g and the CS units 73g assembled with metal spinner = 226g
Stock is 175g putting him an extra 102g (like 10 extra 9g servos sitting at the motor) more in the tail at about 23.5cm aft of CG155.
Not a huge amount over all and the things in the nose that are like 50 to 80cm forward of cg155 would almost immediately counter weight that.
The battery and air brake has less counter weight force cause its closer to CG.

Then he explained that he used 10AWG 75g/m wire for the motor wire length, compared to 14awg 40g/m. So he almost doubled the wire weight but even that's only about 50-70g. Hopefully he didn't over size the motor bullets or added extra solder.

He has heavier ESCs, heavier batteries, L bar Al, a servo up the pilots butt, the air brakes, not sure how he put on the tail ray dome.... he's probably got a bad scale and is more like 3.6kg or he forgot to tell us a lot of other stuff, get carried away with glue... His thrust though may still be only 2.9kg. Going to 6S but turning at much lower rpm to not burn up the motor, he'll be near the same thrust but the amps will be high cause he's well above in Kv. The last estimates there are all guesses. But the 2858-1 was never meant for a CS12.

He'll figure it out. Can he shed some of that weight? I thought I was heavy at 3.4kg when I mount my heavier battery.
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Old Feb 07, 2013, 03:03 PM
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the tail ray dome! thats the answer! TM put the roll of quarters he had been saveing in the dome.
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Old Feb 07, 2013, 03:29 PM
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Su35 Exact Weight

Ok, no more guessing, just weighed on a new digital kitchen scale, the weight of plane ONLY 2690g, 2 batts 890g TOTAL weight = 3580g

Thats not outrageous-- 3.6kg what do you guys make of that?
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Old Feb 07, 2013, 03:31 PM
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I just bought a scale-- weight of dry plane 2680g, 2 batts 890g total 3580g, 3.6kg, its not that bad as I expected... the total weight of all my mods was listed at about 140g max! and all of that forward of CG But still total weight is 400g more than I had planned on... will weigh the motors later today



Quote:
Originally Posted by davemilw07 View Post
OK, Alright...............

What is the weight of your mods, vs OEM equipment????

I'll bet that your fans and motors are heavier than OEM, and at a far aft location, that weight is multiplied by the length from the CG.

What exactly do your fans and motors weigh (combined total)???????????

Regards, Dave


P.S. You know how a seesaw works, don't you????????
I
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Old Feb 07, 2013, 03:37 PM
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Quote:
Originally Posted by Maxthrottle View Post
That information has been posted. The motors he's using is 153g and the CS units 73g assembled with metal spinner = 226g
Stock is 175g putting him an extra 102g (like 10 extra 9g servos sitting at the motor) more in the tail at about 23.5cm aft of CG155.
Not a huge amount over all and the things in the nose that are like 50 to 80cm forward of cg155 would almost immediately counter weight that.
The battery and air brake has less counter weight force cause its closer to CG.

Then he explained that he used 10AWG 75g/m wire for the motor wire length, compared to 14awg 40g/m. So he almost doubled the wire weight but even that's only about 50-70g. Hopefully he didn't over size the motor bullets or added extra solder.

He has heavier ESCs, heavier batteries, L bar Al, a servo up the pilots butt, the air brakes, not sure how he put on the tail ray dome.... he's probably got a bad scale and is more like 3.6kg or he forgot to tell us a lot of other stuff, get carried away with glue... His thrust though may still be only 2.9kg. Going to 6S but turning at much lower rpm to not burn up the motor, he'll be near the same thrust but the amps will be high cause he's well above in Kv. The last estimates there are all guesses. But the 2858-1 was never meant for a CS12.

He'll figure it out. Can he shed some of that weight? I thought I was heavy at 3.4kg when I mount my heavier battery.
Right on Max you nailed it-- total weight came in at 3580g on a new digital scale--plane only 2680g batts 890g so right at 3.6kg., Wires now 12AWG, so thats done, will look at other possibilites to shed tail weight including moving EDFs forward towards CG
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Old Feb 07, 2013, 04:23 PM
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Now that starts to make sense.
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Old Feb 07, 2013, 04:30 PM
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It looked to fly fine, just tail heavy. Take off speed and climb was fine - a good enough clue that it has plenty of power to weight.

I haven't re-weighed mine but it will be about 3.5Kg area. (I don't expect I will get a shock when I weigh it... but might). I am not fussed whatever it is, even back at 3.2kg it showed it could carry a LOT more without issue. Easily 4Kg.
But this next weight level will be another clue as to how much will be best.
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Old Feb 07, 2013, 05:34 PM
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Moving the fans forward? are you nuts? That's the last thing you want move. The duct is clean so don't mess it up moving it around and lengthening the tube.

Shed mods will drop the weight. Take out the L bar Al, If you go heavy in one thing, you can't opt for everyone else's mods too. The air brake, exorcist pilot and what ever other extras cause the 4S was heavy to begin with.
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Old Feb 07, 2013, 05:57 PM
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Pete; you should refine your comment about it flying fine. That depends on the type of flying. Flat orbits isn't what this model is about as its a 3D bird. 2.9kg thrust on a 3.6kg bird, he was closer with stock and is now just harder on his gear.

That's where your quest for weight to be like a composite... you don't see composites doing 3D unless their turbines with enough TWR. And as much as weight inertia creates one set of maneuvers, the 35 has a good TWR to do any of it in the first place.

ITTD take it up and do some 3D to see how yo yo yo fat mama shakes her groove thang! Even with TV on its going to look as slow as scale but you'll need to enter each maneuver with more energy and only do a few things before you lose that energy.

Quote:
Originally Posted by PeterVRC View Post
It looked to fly fine, just tail heavy. Take off speed and climb was fine - a good enough clue that it has plenty of power to weight.

I haven't re-weighed mine but it will be about 3.5Kg area. (I don't expect I will get a shock when I weigh it... but might). I am not fussed whatever it is, even back at 3.2kg it showed it could carry a LOT more without issue. Easily 4Kg.
But this next weight level will be another clue as to how much will be best.
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Old Feb 07, 2013, 06:02 PM
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I believe that some of us (including myself) have been over-thinking this thing.

I started out with stick balsa and tissue paper covered FF models, and the goal was to always keep the model as light as possible, in order to get the best flight performance.

I think that this principle still holds true, even today...........................

Just my opinion,

Dave
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