I cant 3D with my 450 SE. no power! HELP!

I cant 3D with my 450 SE. no power! HELP!
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I cant 3D with my 450 SE. no power! HELP! - 9/24/2007 7:34:51 PM

Flyboywbl

Posts: 202
Joined: 7/12/2002
From: Bozeman, MT, USA
Status: offline

Well i bought a trex 450 se last spring and it flys fine in normal flight but i've been trying to hover upside down and the thing just boggs down and falls out of the sky. I'm using the recomended pich and throttle curve but it won't do an inverted hover to save my life. I have those standard hitec mini servos on the collective/cyclic. and a futaba S9650 on the tail with a futaba 401 gyro. I'm also running the stock align 3550KV brushless motor and the stock align 35A speed controler. I'm using the thunder power 2050 mAh batteries witch can discharge up to 25 C!!! for a reciver i'm using a Futaba 6 channel mini pcm reciver and a futaba 7CHPS for guidence. I'm running the align 315mm woodies. My question is what am i doning wrong? is there a pitch and throttle curve i should be using? Oh i've also not set up the speed controle programing at all. I just soddered on some deans ultra plugs and ran it in the stock configuration. I'm not sure how to do it actually. if this is the situation could some one walk me through programing it? I can hover my Sceadu evo 30 upside down no problem and that is compleatly stock with a crappy os 37 with a muffler and not a tuned pipe. I would think this thing would out preform that buy a mile. any way, any help you guys can give me would be great! thanks
-Matt

oh i also live at 4500' MSL which might also do it. But i've seen guys 3D these things here in Bozeman MT so i know it's possible. Ask them you say... well they stopped comming to the club last year and i've not been able to get a hold of them. thanks again

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RE: I cant 3D with my 450 SE. no power! HELP! - 9/24/2007 8:26:28 PM

samtech

Posts: 201
Joined: 12/21/2006
From: Elk Grove, CA, USA
Status: offline

I'd have another look at that throttle curve. Sounds like it's not keeping the head speed up. I've got mine set up at 100% throtlle at -12, 80% at 0 and 100% at +12. With a 9 tooth pinion I'm siting at a pretty consistant 2700 head rpm.

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RE: I cant 3D with my 450 SE. no power! HELP! - 9/25/2007 12:46:52 AM

HeliTB

Posts: 1207
Joined: 9/14/2006
From: Fort Washington, MD, USA
Status: offline

samtech...What motor are you running?

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RE: I cant 3D with my 450 SE. no power! HELP! - 9/25/2007 3:15:36 AM

samtech

Posts: 201
Joined: 12/21/2006
From: Elk Grove, CA, USA
Status: offline

430l. But I might have to go get the new 430xl. I hear it's got more punch.
Hey Flyboy, Checked that throttle curve yet? You said it flys good right side up. Does it have plenty O power or is it just barely flying? Have you tried a different battery? I've never had good luck with thunderpowers, yours might be fine. Lot's of variables there. ESC, chargers, punishment factor.... Might get a couple of those stick on temp indicators.. keep it under 140 or your frying it.
Do you have a pitch gauge? Positive it has enough negitive pitch?

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RE: I cant 3D with my 450 SE. no power! HELP! - 9/25/2007 2:58:26 PM

ksechler

Posts: 506
Joined: 9/19/2002
From: Frederick, MD, USA
Status: offline

Sam-
Sorry dude, but there is no way in the world you are running 2700 rpm with a 430L and a 9 tooth pinion. The 430L typically uses a 12 or 13 tooth pinion to get headspeeds in the 2500 rpm range and it sure won't turn that with +-12 degrees pitch.

Flyboy:
I have two suggestions. 1). check your negative pitch. It should be -9 or -10 degrees. 2). Make sure the blades are symettrical.
If upright hover pitch is 5 degrees then inverted should be -5 degrees. The motor loading is the same. The motor doesn't care if it is right side up or up side down.

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Post #: 5

RE: I cant 3D with my 450 SE. no power! HELP! - 9/25/2007 3:18:19 PM

soneebee

Posts: 2173
Joined: 3/17/2006
From: las pinas, PHILIPPINES
Status: offline

I am using a 430L with a 13T pinion and I am getting 3200 - 3300rpm head speed... at 90% throttle...

http://www.youtube.com/watch?v=ynF4uYH4F3c

quote:

ORIGINAL: ksechler

Sam-
Sorry dude, but there is no way in the world you are running 2700 rpm with a 430L and a 9 tooth pinion. The 430L typically uses a 12 or 13 tooth pinion to get headspeeds in the 2500 rpm range and it sure won't turn that with +-12 degrees pitch.

< Message edited by soneebee -- 9/25/2007 3:41:40 PM >

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Post #: 6

RE: I cant 3D with my 450 SE. no power! HELP! - 9/25/2007 3:26:43 PM

VinceHerman

Posts: 2284
Joined: 9/5/2002
From: Wadsworth, OH, USA
Status: offline

If it hovers right-sided-up without bogging, I see no reason why it should not be able to hover inverted just as well.
I suspect that your mechanical pitch may not be set up as well as it should.
Do you have a pitch gauge? I would disconnect the motor and check what actual pitch you are getting at 0%, 25%, 50% 75% and 100% throttle stick positions.

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Post #: 7

RE: I cant 3D with my 450 SE. no power! HELP! - 9/25/2007 3:41:50 PM

samtech

Posts: 201
Joined: 12/21/2006
From: Elk Grove, CA, USA
Status: offline

Hey Ksechler. The hell it won't. If you can't get at least 3000 with a 12 or 13 your battery is trash. Go get a quality battery and see for yourself befor you call someone a liar.

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RE: I cant 3D with my 450 SE. no power! HELP! - 9/25/2007 4:56:35 PM

ksechler

Posts: 506
Joined: 9/19/2002
From: Frederick, MD, USA
Status: offline

Sam:

I have a quality battery.

The 430L is 3550 Kv. So at 12V that's 3550*12=42600 rpm
The Trex has a 150t main gear. You are using a 9t pinion. So 9/150=0.06
So your headspeed is 42600*0.06=2556

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Post #: 9

RE: I cant 3D with my 450 SE. no power! HELP! - 9/25/2007 5:19:08 PM

lookyj

Posts: 809
Joined: 2/3/2007
From: Northridge, CA, USA
Status: offline

so is this equation absolute in calculating RPM?

Kv * V * [pinion/gear] = RPM

but that doesn't account for real life variables, with the number one being the true voltage you are getting from your battery. other factors include: Rotor Length, Drag (pitch, wind), Heat.....

what is the correct formula for calculating voltage from your LiPo? I know 3s are rated at 11.1v but what about the continuous and burst rating, battery life, charge rate, amp draw, fully charged pack or how much flight time have you already used....

from my experience all LiPo's are not created equal, and I've owned several through out the learning curve, currently I have:

Thunder Power 3s 2100mAh 15C
DN Power 3s 2150mAh 20C
Mega Power 3s 2100mAh 15C
Align 3s 2100mAh 15C

I'm running the stock SE setup with DX7, AR6100, (3) HS65HBs, Futaba 401 and S9650 on the tail

< Message edited by lookyj -- 9/25/2007 5:23:08 PM >

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RE: I cant 3D with my 450 SE. no power! HELP! - 9/25/2007 7:24:12 PM

ksechler

Posts: 506
Joined: 9/19/2002
From: Frederick, MD, USA
Status: offline

Actually it does take into account voltage from the Lipo. 3550 kV refers to the rpm per volt. So 3550 rpm per volt yields 3550*12=42600. As far as loading (rotor length, pitch, efficiency) the motor will just pull more amps to maintain speed. The speed of the motor is determined by the physical characteristics (i.e. the armature and windings) and voltage.
The hp=(Volts*current*efficiency)/746. So your 3550 kV motor on 12 volts will turn 42600 rpm until you exceed the motor's power. Then it'll just keep pulling more amps and getting hot. Eventually it will burn up.

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RE: I cant 3D with my 450 SE. no power! HELP! - 9/25/2007 7:53:14 PM

lookyj

Posts: 809
Joined: 2/3/2007
From: Northridge, CA, USA
Status: offline

good to know thanks!

curious about the 12v coming from the LiPo...

I charge my LiPo's independendantly using DN Power's G2 charger. I charged until each cell is at 4.2v (12.6v total) and run the batteries until each cell is at 3.7v (11.1v) which is usally about 6 minutes of FF with my TREX 450S. This means the voltage ranges from 12.6 volts to 11.1 volts as it discharges..

what about the C rating?

I believe this has to due with the amps draw during usage, charging and discharging.

C Rating / 10 = the max amp charge rate.

ex: 15 C / 10 = 1.5 amp charge rate.

So it is the amp draw that is affected during increase and decreased load, (throttle up to a fast climb)

How do these factors relate in the RPM equation?

the reason I ask is I noticed a drastic change in performance between my DN Power Battery and my Thunder Power Batteries.... my DN's are about 6 months old where as my TP's are brand new. the DN are rated at 2150mAh 20C and my TP's are rated at 2100mAh 15C. The DN lack the power to do a fast climb and runtime is only about 5 minutes, where as my TP's last about 7 minutes and have great climbing ability

I've been wanting to learn 3D and inverted, but my last 2 loop attempts have ended in some time on the work bench. After purchasing the new set of LiPo's, I'm wondering if the DN's did not have enough power to pull the heli out of the loop resulting in my crashes?

< Message edited by lookyj -- 9/25/2007 8:03:58 PM >

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RE: I cant 3D with my 450 SE. no power! HELP! - 9/25/2007 8:04:05 PM

samtech

Posts: 201
Joined: 12/21/2006
From: Elk Grove, CA, USA
Status: offline

Takes it into account.... Really? Well then, at 42600 rpm with the 13 tooth you mentioned early as getting 2500 RPM???? So I guess it must really get 3692 and I'm really only getting 2556. Jeezzzz, to think I was only getting 2556 the whole time....

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RE: I cant 3D with my 450 SE. no power! HELP! - 9/25/2007 9:59:24 PM

ksechler

Posts: 506
Joined: 9/19/2002
From: Frederick, MD, USA
Status: offline

Sam, if you think your sarcasm masks your lack of accurate data then you're wrong. Reread the posts. I have supported my comments with DATA and CALCULATIONS. You supported yours with a smart a$$ attitude.

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Post #: 14

RE: I cant 3D with my 450 SE. no power! HELP! - 9/26/2007 1:35:54 AM

samtech

Posts: 201
Joined: 12/21/2006
From: Elk Grove, CA, USA
Status: offline

Well, now that we completely hijacked this guys thread (sorry bout that). It's your calculation that is contradicting your statements. 13 tooth, 42600*0.0866=3692. Not the 2500 you so boldly stated. Neither of which is accurate in the real world. I know my tachometer is reading correctly as I have checked it against two other units. So, who's the smart A$$? Me or the guy who insist I'm wrong about my own machine? I'm sorry if you’re getting lackluster performance from yours but mine runs like a champ. Did you check out Soneebee's youtube? That is what a 13 should do. That is real world performance. 3100-3200 Heat, parasitic drag and countless other variables. Your calc's are valueable for the most part but it's your ego and your attitude tha