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capacity estimator for sequences ?

Old 07-29-2014, 06:44 PM
  #1  
ltc
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Default capacity estimator for sequences ?

Hi,
is there a rule of thumb or estimator for the required battery capacity for a 2m plane flying the various sequences?
for example, for a 2m plane flying Sportsman,,would 5000 sufficient or would a 5400 pack be required?
thanks
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Old 07-29-2014, 07:06 PM
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ltc,

5000mah should quite a bit more than enough to fly the Sportsman sequence (1 sequence). Your mah usage will be influenced by many things - speed, wind, weight, how hard you throttle, prop, etc. So it is pretty hard to say how much capacity you need to fly a given sequence. Maybe other Sportsman flyers can chime in here with what they are using, what motor/prop and plane, to give you an idea of what is used for that sequence.

Woodie
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Old 07-29-2014, 10:45 PM
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As Woodie says, there are many variables. I'm flying the intermediate class with a light plane, the Shinden, with the Himax motor and a 20.5 x 14 prop. I'm using about 2800 mah per flight. I start my timer after I taxi out to the centerline and get lined up. I usually finish my sequence at the 6 minute mark and do the standard turn around and land at about 6:20.

I bought a 5000 pack thinking I could practice a little longer but the weight difference made the plane handle differently so I don't recommend that.

So, the bottom line, I would suggest the 4400 mah packs.
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Old 07-30-2014, 05:36 AM
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Thank you.
The reason for asking the question was based on something I discovered while looking at the ThunderpowerRC website.
It would appear as though their G8 25C 5s 5000mA pack (574g) weighs the same as their G8 25C 5s 5400 pack (573g)
(Granted, the pack dimensions are different but nothing that isn't manageable)
Interestingly enough, the $ per mAH for each pack is about the same.

That made me wonder if there was a capacity requirement that would make someone use the 5400 rather than the 5000.
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Old 07-30-2014, 09:53 AM
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As the sequences get more complex, they also get longer, so the need for capacity goes up. I am currently flying a 2M Vanquish using 4400 mah packs. I am still getting used to the plane, but in general I will use about 2500 mah for the Intermediate sequence. I normally set the timer for 7 minutes which allows me a few additional passes/maneuvers. On a really windy day, I have seen consumption go up to 2900 - 3000mah. For the sportsman sequence, I would imagine that the consumption would be closer to 2000 mah.

Good luck,

Teo
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Old 07-30-2014, 02:25 PM
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On a 2M pattern plane usually 10 cells 5000 mAh can be a good compromise so You can fly on more throttle in windy conditions without worry about getting low on capacity (and ruin Your LiPo by over disharge them). I use ThunderPower G8 25C Pro lite+, 4 cell x 2, 5000 mAh, in my MythoS 125E and same type of ThunderPower LiPo but 5 cell x 2 on my MythoS Pro 2M. On windy days when flying Advanced Schedule I can consume around 3300-3500 mAh when flying my MythoS Pro 2M. I'm seldom below 30% of capacity so it feels good to not need to worry about not even come close to 20% capacity rule of thumb.
Above is with Hacker Q80-14XS and Falcon Electric carbon V2 prop 20.5 x 14.5.

About the form factor on the ThunderPower LiPo - 5000 vs 5400 mAh: Yes they are about same weight and I have tried the 5400 mAh (4 cell x 2 in my MythoS 125E) and it works fine but I do not really like the tall pack. I prefer the lower profile 5000 mAh. See photos below of comparison of the two packs.

/Bo
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Last edited by bem; 07-30-2014 at 02:29 PM.
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Old 07-30-2014, 02:54 PM
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Thank you for the reply and photos.
I called Thunderpower and asked about the 5400 form factor. Apparently they are a replacement for the previous 5300 mAH F3A packs, since they are closer in form factor than the 5000
Here is the discontinued 5300 packs I am referring to:
http://www.espritmodel.com/thunder-p...ery-packs.aspx
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Old 07-30-2014, 04:28 PM
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I run the 5400's for the simple fact like you stated they weigh the same as the 5000's. The form factor is a little different but for me it's nicer to be able to move the cg around as it's more of a cube instead of a rectangle.

As as far as mah goes you can use between 8 and 9mah per second for battery use. I've done some asking around and the lighter airplanes that are not as hard on the throttle is 8mah a second and heavier users of the throttle are about 9mah.

Andrew
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Old 07-31-2014, 03:42 PM
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If you're flying Sportsman, get the biggest packs you can fit and stay within the weight requirement (which is padded a little for Sportsman and other classes). The most important thing when you're starting is flight time. Why limit yourself?

I got 4500mah packs for my new 2M airplane - I thought the plane would be heavy and would need the lighter packs to make weight. It turns out I can afford more weight, and when I practice I am constantly pushing my packs to their capacity limits. It's so annoying to be limited to short flights when you don't have to be.

For reference, I'm flying Intermediate. At contests I use anywhere from 2800-3300mah per flight depending on the wind. A 4500mah pack gives you 3600 usable mah if you plan on following the 80% rule. I think my timer is set to 7.5min during practice. Every time I think I can push it to 8min I exceed the 80% rule. 80% rule means you want to use no more than 80% of the battery's capacity, to maintain adequate voltage in the cells (especially under load) and not damage the packs. I miss the 9min flights I had with my 110 size airplane and don't really like flying the last few maneuvers during practice knowing I should be watching throttle on verticals. The best setup leaves you concentrating on flying and nothing else.

A lighter plane will handle a little differently, but any decent 2M airplane should fly just fine at or under 11.x lbs.

I am thinking about getting 5400 or 5800 packs for next season so I can fly a little longer and get a little more practice in per flight.

Last edited by Jetdesign; 07-31-2014 at 03:47 PM.
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Old 07-31-2014, 03:53 PM
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AJ that 8-9mah is an amazing piece of knowledge to have! Thanks!
8mah/sec is pretty much spot-on for me right now (4800mah pack needed for 8 min + 20% reserve; 5400mah for 9 min + reserve).
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Old 07-31-2014, 05:59 PM
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Thank you everyone for the replies.
I just ordered 4 G8 5s 5400 packs from ThunderpowerRC.
They had sent me a 20% off coupon that was about to expire so I figured it was time.
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Old 08-01-2014, 07:55 AM
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Originally Posted by Jetdesign View Post
If you're flying Sportsman, get the biggest packs you can fit and stay within the weight requirement (which is padded a little for Sportsman and other classes). The most important thing when you're starting is flight time. Why limit yourself?

I got 4500mah packs for my new 2M airplane - I thought the plane would be heavy and would need the lighter packs to make weight. It turns out I can afford more weight, and when I practice I am constantly pushing my packs to their capacity limits. It's so annoying to be limited to short flights when you don't have to be.

For reference, I'm flying Intermediate. At contests I use anywhere from 2800-3300mah per flight depending on the wind. A 4500mah pack gives you 3600 usable mah if you plan on following the 80% rule. I think my timer is set to 7.5min during practice. Every time I think I can push it to 8min I exceed the 80% rule. 80% rule means you want to use no more than 80% of the battery's capacity, to maintain adequate voltage in the cells (especially under load) and not damage the packs. I miss the 9min flights I had with my 110 size airplane and don't really like flying the last few maneuvers during practice knowing I should be watching throttle on verticals. The best setup leaves you concentrating on flying and nothing else.

A lighter plane will handle a little differently, but any decent 2M airplane should fly just fine at or under 11.x lbs.

I am thinking about getting 5400 or 5800 packs for next season so I can fly a little longer and get a little more practice in per flight.
Joe, take a look at the Tech Aero Throttle Tech. It is advertised as a device to make your throttle response constant throughout the flight as the battery voltage drops off. It does that well and at the same time allows a lot more flight time. I found that I didn't need any more than 60 Amps (less than 2400 Watts) on my Contra powered Axiome for any of the FAI P-15 maneuvers so that is how I set up my TT. Another benefit in my mind, is full throttle is the setting I want on vertical maneuvers and there is no guess work trying to get the right setting. Anyway, I typically fly the P-15 on less than 3000 mAh and can fly a number of extra maneuvers and stay under 4000.

Jim O
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Old 08-04-2014, 08:03 PM
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On my 2 meter Evolution, I can fly 2 Sportsman sequences back to back on Zippy 5000 packs and have 20% left. I can fly 1 Intermediate sequence with 40% left. Wind seems to be a big factor in my flight times..as much as 2 min less with 10-15 mph winds. I can fly 1 Sportsman sequence on Zippy 4000 ma packs, with 25-30% remaining.
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Old 08-05-2014, 09:09 AM
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Thanks.
I will be depending on my telemetry to provide battery capacity status and "time to land alarm" based on state of charge, so I think I should be OK with the TP packs I ordered.
When you referred to the 2m Evolution, is this the plane? http://www.generalhobby.com/evolutio...ane-p-463.html
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Old 08-05-2014, 09:16 AM
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Originally Posted by ltc View Post
Thanks.
I will be depending on my telemetry to provide battery capacity status and "time to land alarm" based on state of charge, so I think I should be OK with the TP packs I ordered.
When you referred to the 2m Evolution, is this the plane? http://www.generalhobby.com/evolutio...ane-p-463.html
Yes
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Old 08-12-2014, 06:23 PM
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I was thinking about this thread. This past weekend I flew my Integral in an IMAC contest. Curious about extending flight times, I propped down to a 19x12W APC. I was previously using a 20.5x14 APC with my Pletty Advance. I hate to say it but I don't have any data to back up the difference I felt.since I don't have data logging. I can say that at first I was really hesitant to use throttle since we fly the sequence twice per flight. But after the first day I only put 2600-2800mah back in the packs. The next day I flew bigger with more throttle and the voltage after landing was not really different from the previous day. This is with 4400mah packs. My feeling is that the flight was fairly similar to one Intermediate sequence in time and difficulty (barring the spin). I was flying bigger and farther than I had been practicing so I think the power demand should be somewhat similar. Previously I had a couple of extra maneuvers of energy left in the battery after a sequence, and if I had used throttle like I did this past weekend, I'd have killed a pack.

I know some guys are limiting the throttle in their radios. I actually loved the feeling with the smaller prop - the throttle response was a lot smoother and it was nice to be able to use up the range of stick travel. I'm going to try a 20x13 before next pattern contest. I would like to get data logging (really telemetry) at some point but I need to put my money in other places these days.

I'll post what I find after I fly a pattern sequence again with the small prop and use the timer I normally use.
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Old 08-15-2014, 05:15 PM
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7min intermediate sequence = 2400mah with 19x12W. Plenty of power. Not bad! I have yet to put back more than 2800mah with the smaller prop and flying over 8min.
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Old 08-16-2014, 07:17 PM
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Hi Joe,

I had a similar experience after trying different prop on my plane. Initially I used an APC 20.5x14W and the plane had great power (Vanquish, torque motor), but I was a little concerned about how warm the motor was getting. For grins, I tried a Xoar 20x13 (electric) and found that the motor response was smother. If anything, it would spool up a little faster. There is a 2oz different in the weight of the props and it had never crossed my mind that the prop inertia would have such a significant effect (the prop being a little smaller might have helped also).

Power consumption went down a little, but on windy days, I have to lean on the throttle a little harder.

Teo
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