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Logo 600 › Logo 600 vbar, 12s A123, what motor?
02-06-2008 01:25 PM  10 years agoPost 1
Skeysl

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Brno, Czech Republic

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Hello,
I'm looking for setup recommendations for Logo 600 vbar and 12s A123 batteries for sport/soft 3D flying. I'm not looking for a extreme power but I would like to get a good power/duration (at least 5min). My choice is Jazz 55-10-32 and Tango 45-06 or 45-07. Which one is going to be better for 12s A123? Is there a better motor for my application? I know that there are many Actro and Orbit motors in 600s but I'm afraid that they're going to suck the energy from A123 too quickly.

My second question is which servos for cyclic for vbar and what BEC would you recommend? S3152 servos are very cheap but are they strong enough? 9451 look great but are quite expensive.

Thanks for all inputs.
Tom Sk

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02-06-2008 02:32 PM  10 years agoPost 2
MrMel

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Gotland

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Tango 45-06 is my bet, with a 17T:ish pinion.
Question is though the duration... if you gonna get 5+ minutes you need to go 12s2p 4600mah...

Efficiency is pretty much the same on todays motors,
Motors dont "suck" the power out of a battery, they can either deliver power or not. Meaning if you lower the pitch and RPM on a Orbit or Actro it wont pull more then another motor.
However, If you raise the pitch & RPM the "less" motor will bog, where the "more" motor will not.

VBar needs stronger servos then without, go for the 9451.
For BEC, You cant go wrong with a Western Robotics 5Amp version (High Current)

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02-06-2008 04:40 PM  10 years agoPost 3
Skeysl

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Brno, Czech Republic

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Thanks MrMel,
I'll go with 45-06, 9451s and Western Robotics BEC.

I would like to avoid parallel pack configuration so I'll consider putting more cells into pack (14s, 15s). Downside is that I'll need different ECS (CC85 or new Jive) and my charger is limited to 50V.

My flying style is really boring (big loops, rolls, inverted, no sudden collective changes) and I was hoping that vbar is going to give me desired flight time...

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02-06-2008 05:10 PM  10 years agoPost 4
MrMel

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Gotland

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I ran 13s with Jazz 55-10-32, its on the high side, but it worked.

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02-06-2008 07:09 PM  10 years agoPost 5
Skeysl

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Brno, Czech Republic

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Great, thats good to know! After all, I'm going to start with 12s knowing that I could add one more cell later...

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02-06-2008 11:28 PM  10 years agoPost 6
fergus

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Ireland

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I think 5mins on 12s a123 is doable. you would need to acheive an average amp draw of about 27amps. Assuming 3volts per A123 cell under load gives a pack voltage of 36volts. Thats about 1000watts for a power requirement. Assuming 12Ibs for the logo 600 on 12s A123 thats 84watts per pound which I think with a low headspeed and just sport flying is not unreasonable. The Kontronik gear would be my advice also. I think the 17tooth pinion will leave the headspeed a bit high for sport flying. 14 tooth on the 45-6 would be better by my calculations.

If anyone has logged their logo600 sport flying If they could post their flying weight and average watts then these figures could be checked.

Regards

Fergus

Regards

Fergus

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02-07-2008 01:43 AM  10 years agoPost 7
jrvander

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Camp Foster, Okinawa japan

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Fergus,

Does your heli really weigh 12 pounds? Seems awfully heavy. My Logo 14 only weighs in at 7.5 pounds with battery RTF. An A123 cell is about 70g, so 12S should be 840g. Add a few grams for wires and such, that comes in at roughly 2 pounds for the battery, so your heli is 10 pounds without battery. Just seems really heavy for a Logo to me.

- Jon

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02-07-2008 07:42 AM  10 years agoPost 8
MrMel

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Gotland

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14T will bog, badly.

RPM at low load (2-4C): 2147 at 37,8 volt
RPM at medium load (13-15C): 1875 at 33 volt
RPM at full load (>23C): 1568 at 27,6 volt

Key to get any kind of flying performance out of A123 is to gear towards the lowest RPM you want to see during load, and limit the governor/curve on the ESC to keep the headspeed down.

This is needed because the A123 voltage drops so much.
Of course its at a cost of flight-time.

However, my initial 17T assement was a bit high (was calculating with 600kv), 16T suits better.

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02-07-2008 02:21 PM  10 years agoPost 9
fergus

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Ireland

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Jrvander I am unsure of the weight of the Logo 600 and did make an assumption in my post as I said. I do not have a 600 myself. I was trying to illustrate that 5mins flights were possible with 12s a123 at that weight if the average amp draw was kept around 25-30amps.

MrMel I accept what you say about gearing on A123 and the low voltage seen at high load. But given the requirement for a sport setup if 20+C loads are pulled then its unlikely that 5mins will be achieved anyway. Anything more than 12-15c would reduce the flight time considerably I think.

I was also calculating for 600Kv motor and thinking of a headspeed around 1800rpm for a sport setup with good duration.

33volts x 600 = 19800motor rpm
153tooth/14tooth= 10.928 (gear ratio

19800/10.928= 1811 rotor rpm

I hadn't factored in efficiency so the higher pinion would be better I guess. Not to high that the ESC gov becomes inefficient and reduces flight time though.

Regards

Fergus

Regards

Fergus

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02-07-2008 03:11 PM  10 years agoPost 10
rerazor

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Mich.

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No way its over 10lbs. My L5003d, with 10s1p A123, MS515mm blades is 6lbs 6oz. I get 5mins no problem with a headspeed around 2250rpm at spool up and then it will drop to around 2100rpm once the pack levels out at 30volts, it will hold that headspeed until the end.

Like MrMel says, gear for 3v per cell and you are good to go with A123's.

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02-07-2008 03:56 PM  10 years agoPost 11
Skeysl

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Brno, Czech Republic

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I did some calculations too and I'll go with 16T pinion as MrMel suggested. With 12s I'm expecting AUW 3.5Kg maybe less. The only question is flight time. I can try to compare it to my other A123 powered heli - 525mm blades, 9s, 2.5Kg, flight time 5:30. But 525mm blades and 600mm is huge diference in heli size.

Also I'm tempted to try BLS451 for cyclic and BL251 for tail.

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02-07-2008 03:57 PM  10 years agoPost 12
fergus

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Ireland

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Where did I get 12Ibs from

Anyway the lower weight is all the better so go for it. I don't think you will need to go 2p as MrMel says. 5mins+ on 12s a123 especially with the lower drag of the vbar and sport flying should not be a problem.

Regards

Fergus

Regards

Fergus

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02-08-2008 11:18 AM  10 years agoPost 13
Skeysl

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Brno, Czech Republic

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I'm going to try it. Thanks for all advices!

Tom

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02-09-2008 03:33 AM  10 years agoPost 14
wlfk

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uk

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My logo 600 is 3.7kg with 9s2p A123 - the pack weighs 1.4kg and so is only slightly lighter than the airframe.

I haven't timed my flights yet, and I was having so much fun that my estimates will be rather poor. But I'm pretty sure I got 5 minutes. Will hopefully find out this weekend and get back to you.

K

A bit like a kite, but 500 times more expensive

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02-10-2008 12:37 PM  10 years agoPost 15
Skeysl

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Brno, Czech Republic

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Wow! That's 18 cells and weight still isn't bad. I'm curious, do you have a picture of the pack and how to fit it inside logo frame?

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02-10-2008 04:06 PM  10 years agoPost 16
rerazor

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Mich.

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9s2p A123 is like a 7s lipo. I would run 13-15s in 1p configuration or for duration run a 10s2p setup.

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02-10-2008 04:49 PM  10 years agoPost 17
wlfk

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uk

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I took pictures of it, finished and during assembly. I'll try and get them from my home computer to here at some point soon.

It's a regular 4x4 pack, with 2 extra cells stuck on top, with a slight stagger to keep them clear of the frame. There's about 2/3 overlap between them and the cells below.

I finally got a figure for duration: about 8 minutes of gentle forward-flight and hovering (about 50/50) with 3 strong pullouts just to demonstrate what she can do (full collective until orientation starts to get iffy). Bat out of hell. Headspeed is 1833rpm with a Z-Power 780kV motor and the largest pinion, which if memory serves is 19t. That's on a Castle-Creations hv85 governed to 75%.

Balance: if you lift it up by the rotorhead then lower it to the ground, the rear skids lift off about 5mm higher than the front. This isn't quite as good as it sounds, because with the skids flat the main rotor is tilted slightly forward. I have a dx which has a slightly shorter tailboom than the 3d, so I suspect the balance would be just about perfect with the longer boom. I'm planning to stretch to 690-710 blades at some point, so with an even longer boom I'm hoping to get a fairly even balance. The 8s pack balanced with the skids completely flat. I considered a 10s2p pack but thought it would be a bit unwieldy.

K

A bit like a kite, but 500 times more expensive

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02-10-2008 10:03 PM  10 years agoPost 18
rerazor

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Mich.

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A nice site to easy A123 construction. For the Logo 500/600 you will need the end to end config.

http://www.slkelectronics.com/DeWalt/hints.htm

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