800 Mah 2S Battery for Simple Storch?

[SrTelemaster 150]

I built a Simple Storch with the "C" power pack (E-Max GT2215/09 motor). The airframe sans battery balances ever so slightly tail heavy so the weight of the battery pack will not affect CG as it can be shifted ahead of the CG and the majority of the battery pack mass is also ahead of the CG.


I have a 2200Mah 3S pack and it does balance the plane with room left to shift forward.

Here's my question. Would an 800Mah 2s pack work with that motor for low speed lighter weight trainer application? Will the 2s pack power the motor without damaging the pack and/or motor? My basic understanding of electricity and Ohms law leads me to believe that the lower voltage would push less amps through the motor and thus extend the time that the smaller Mah pack will be able to power the plane. Is this true?

So, I came shave about 2 1/2oz off of the AUW by going to the 800Mah 2S pack dropping the AUW from the present 38oz down to 35 1/2oz, or I can go to a 1300Mah 2S pack and drop weight to 36 1/2oz.

I plan to keep the 2200Mah 3S for advanced, more aerobatic flight options as I regain my (now rusty) skill level, I would just like the most docile characteristic possible for trainer use until I get used to flying again. I have a few years of 4-stoke powered flight R/C experience, but it has been a long time and I'm new to electric.

 

[Bricks]

I think with the Storch 2S is not going to have enough power to fly it stick with the 3S and just use throttle to slow down the Storch is a pretty floaty plane the way it is..

You do not want to fly it tail heavy most planes get very twitchy and hard to keep from climbing and stalling .

 

[SrTelemaster 150]

I think with the Storch 2S is not going to have enough power to fly it stick with the 3S and just use throttle to slow down the Storch is a pretty floaty plane the way it is..

You do not want to fly it tail heavy most planes get very twitchy and hard to keep from climbing and stalling .

It's not tail heavy with a battery pack. I said it was very slightly tail heavy sans (without) battery pack.

 

[DamoRC]

For S&Gs I did a quick test using an NTM 2826 1200Kv motor (close to, but not exactly the same spec as the C pack motor). Mounting the motor to a scales with a 10 x 4.5 prop (similar to the one provided with the C pack kit) I ran tests using both 2200mAh 2S and 3S, both fully charged at time of testing and results are at 100% throttle.

2200mAh 2S drew 12.6 amps and generated a static thrust of 23 ounces (approx 0.65 : 1 thrust to weight for your 800 mAh 2S AUW)
2200mAh 3S drew 21.2 amps and generated a static thrust of 39 ounces (approx 1:1 thrust to weight for your 2200 mAh 3S AUW)

Run time on the 800mAh (assuming 80% discharge at the end of a full throttle flight) = ~3 mins
Run time on the 2200mAh (assuming 80% discharge at the end of a full throttle flight) = ~5 mins

Current draw as a percentage of calculated max current draw the battery can deliver (assuming both are nominally 20C and running full throttle):
For the 800mAh you'll be running close to 80% of max current draw supported by the battery.
For the 2200mAh you'll be running close to 50% of max current draw supported by the battery.

Watts per pound for the 800mAh version = ~40 (on the low end of power needed for slow flying)
Watts per pound for the 2200mAh version = ~ 105 (into sport / acro range in terms of power to weight).

In conclusion, extensive testing and sophisticated data analyses confirm that you should stick the 800mAh into the plane and see if it will work. If not, the 2200 definitely will.

DamoRC

(had my nerd fix for tonight - thanks for the question)