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Swappable Powed Pod: battery size questions

ivan747

Junior Member
#1
Hi, I'm in the process of getting parts for my Power Pod. I basically ordered almost the same setup recommended here:
http://flitetest.com/articles/swappable-fuselage-speed-build-kit
I chose the HobbyKing ESC, 8x4 prop, the Hextronix motor and a $30 Turnigy TX/RX combo (same features as the HK one, except it looks more professional :rolleyes:)


Now there comes the question. I haven't flown an RC plane yet, so I want a slow flying Nutball and FT Flyer, but I also want to have long battery life, about 20 minutes. The reason I want such a long battery life is because I have already experienced the frustration of a low capacity battery in an old eletric RC truck my dad had.

I chose a Turnigy 3S 1000mAh battery. Do you think that's gonna force the Flyer to fly significantly faster than with the recommended 2S 500mAh? If so, could you still fly it in the same area as, say a basketball court and a half? And do you think I can really do 20 minutes with this motor?
http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=2069&aff=247441

If I cannot get both flight time and slow speed I could get both packs and deal with it I guess. I think the 3S pack and a new motor could power the more advanced swappables.

Cheers!
Ivan

P.S. If I get replies I'm going to upload pictures of my humble NutBall with no electronics (yet), all made with local supplies.
 

xuzme720

Dedicated foam bender
Mentor
#2
That battery should be fine, later. You will have to fly a little faster, but not so much as to be uncontrollable. I WOULD recommend getting the smaller battery to start with, and finding a larger area for the first few flights. The Flyer is very forgiving but more room will be a huge help on your first few flights, and preferably somewhere with soft grass will also be a good thing.

Welcome to the forum! You'll find a lot of good people and even more help with getting started!
 

ivan747

Junior Member
#3
Thanks!

Ok, I guess I will get both of them. I would still like to know if 20 minutes is possible, as batteries are charged at up to 2C, that means 30 minutes charging time minimum. It would be sweet to have 2 packs that last 20 minutes each and fly while you charge the other when I get experience.

As promised:

There it is:
image-2.jpeg
Perfectly symmetrical
image-4.jpeg
I taped all around plywood cutout after cutting it, it was very very brittle. After my layer of tape and the recommended layer around the wood and the foam it feels as sturdy as plastic. Reminds me of how laminated glass is made.

I cut the large hole with my hobby knive. The square cutout is quite brittle on the bottom but it is a bit easier to cut the shape. I haven't made the guide holes for the motor mount, but I have tiny drill bits for that. For the 2 holes in the top I used a drill bit I thought was good enough. To drill and cut all of this I really recommend a hard surface with a small 1cm, or 1/2" opening on it for your knive and drill to pass though.
image-3.jpeg
I glued the fin on the bottom instead of the top. I seemed more obvious to me. It will work just like a solder joint, the fin will not shear off and tear the paper from the foam board. It might bend instead. It is also lighter
image-7.jpeg
No reinforcement on here, I'm not sure if it's needed, as I glued the fin on the bottom and the slot keeps it well aligned.
image-6.jpeg

And that's it. If some moderator could add to the title "- Mini Bonus: Nutball build", that would be grat
 
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xuzme720

Dedicated foam bender
Mentor
#4
I love both the Nutball and the Flyer but I'll give you a bit of free advice. Start with the Flyer. It's much easier for a new pilot to fly. Both are a lot of fun to fly but the Nutball can be subject to pilot induced oscillation and can quickly get out of control with too much rudder input. Simply put, it will dutch roll with little warning. The Flyer is just much more forgiving for a first time pilot.
That being said, I like what you've done on your Nutball!
 

ivan747

Junior Member
#5
Yes, the Flyer is next in line. I built the Nutball first without knowing it will be harder to fly. I know realized that the NutBall is the easiest to build and the Flyer is the easiest to fly. I already built the Nutball, so I will build the Flyer, as it's just $4 in servos and $4 in foam, as that is the price for foam board around here. I will fly the Flyer first and then the Nutball.
 

rcspaceflight

creator of virtual planes
#6
You might have accidentally done it the best way. You built the easiest plane first. So you know better how to make the slightly more difficult flyer. But you can still start flying the flyer first and then fly the nutball once you have the flyer figured out.

You could always buy multiple 500mah 2cell batteries and change them every 5-7 minutes. I don't want to burst your bubble, but it's going to take you a while to be able to keep the plane in the air for longer than 3 minutes.
 

titan

Junior Member
#7
Based on the way your Nutball looks you are going to have no problem building a top notch Flyer. Also, check out the Flyer thread, there are some very nice examples with airfoil added to the wings.

titan
 

ivan747

Junior Member
#9
You could always buy multiple 500mah 2cell batteries and change them every 5-7 minutes. I don't want to burst your bubble, but it's going to take you a while to be able to keep the plane in the air for longer than 3 minutes.
The thing that gets me is that a 2S 500mAh battery is almost the same price as a 3S 1000mAh battery: $4 vs $5.50. I don't understand why HobbyKing sells this Turnigy 1000mAh...
http://www.hobbyking.com/hobbyking/store/__9163__Turnigy_1000mAh_3S_20C_Lipo_Pack.html
...cheaper than an equivalent 800mAh pack, which is $7.09.

And you are probably right about the flight times, but it is nicer if I am not forced to stop by a discharged battery. I guess I will deal with it for the moment.

One thing I could do in the future to fly continuously is to get some of these cheap Turnigy chargers, for $4.50 each (amazing!):
http://www.hobbyking.com/hobbyking/store/__7637__Turnigy_balancer_Charger_2S_3S.html
And charge multiple batteries out of any 12V power source like a power adapter, a lead-acid battery or a car's 12V socket. Having, say a 10 minute flight time and 30 minute charge time, you get 3 batteries and 2 chargers and you should be able to fly continuously.

That's a Flite-Test Flite-Tip
 
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rcspaceflight

creator of virtual planes
#10
A higher "C" rating always costs more. The real cheap batteries usually have a rather low "C" rating. The weight of the battery is also a big factor in price. They can charge more money for the small light batteries because people want them for the weight savings. I think. It also has to do with popularity. It's why the 9gram servos cost less than the 5gram servos. Pretty much everyone uses the 9gram servos so they can charge less because they know they'll sell. More popular items become cheaper with Hobby King.

The battery you linked looks like a good choice for an FT Flyer/Nutball. You may have to fly a little faster, but not really noticeably and you'll get used to it. I really like your idea of having multiple chargers so you could theoretically fly non-stop.

I've really never gotten into the buying multiple batteries of the same size. I have a few batteries of different sizes. Mostly because I live on a farm and I don't mind having to take a break between flights while I charge a battery. It can be good to have a few of different sizes for different applications, but it's not really necessary.
 

xuzme720

Dedicated foam bender
Mentor
#11
One thing I could do in the future to fly continuously is to get some of these cheap Turnigy chargers, for $4.50 each (amazing!):
http://www.hobbyking.com/hobbyking/store/__7637__Turnigy_balancer_Charger_2S_3S.html
And charge multiple batteries out of any 12V power source like a power adapter, a lead-acid battery or a car's 12V socket. Having, say a 10 minute flight time and 30 minute charge time, you get 3 batteries and 2 chargers and you should be able to fly continuously.

That's a Flite-Test Flite-Tip
I would not use that charger. I had a similar one that fried itself and almost killed one of my lipo's and could have started a fire in the house if I wasn't babysitting my battery. Someone else had one that unbalanced their batteries to the point of fire also. Better to spend a little more for a good charger that won't set the house/car on fire. Cheaper in the long run!
 
#12
The recommendation I've always heard is to get two small batteries (~800Mah), rather than one huge battery (~2000Mah), unless you have a large and powerful plane. I bought two 800 3 cells for my FT Flyer, although I haven't had the time to put it together yet.
 

ivan747

Junior Member
#13
Seems like you are right about the quality of the charger:
https://sites.google.com/site/donutscience/various-projects/fixing-the-cheap-one

I was very curious with this charger. I was surely going to take it apart, but he already did it for me. I haven't seen the article in depth, but I am going to.

In conclusion, the charger appears to be truly bad and maybe dangerous, but I liked the idea of a compact 12V charger.

Edit: I forgot to say I am very familiar with electronics, I've had it as a hobby for about 4 years, so I can tell a bad circuit from a good one and maybe fix bad circuits.

Edit 2: It is possible to fix the charger but I see some faults in the design that are not worthwhile to fix. For example, I'm not sure if their method of balancing the charge is safe, as it is not monitored and may not be precise even after the mods. If you put garbage in, you'll get garbage out, even if you try to fix it.

I might go for the Turnigy Accucell if I get a good deal and if I can program it to be used for non-RC batteries, so I can keep it around my electronics lab for other projects.
 
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xuzme720

Dedicated foam bender
Mentor
#14
I have the Accucel 6 and it works well for all of my charging except my Tx batteries. Those have to be charged through the balance ports only so I use a different charger on those.
 

ivan747

Junior Member
#15
I almost finished the NutBall the other day. I'm only missing the electronics, I'm going to order them today form HobbyKing, as they have 10% off the whole site until tomorrow. I'm going for 2 500mAh 20C LiPo's because of that, along with the Accucell charger.

Now I discovered a flying field in my city, Santo Domingo (Dominican Republic) that is open to the public for free. It's apparently the largest one in the Caribbean, it's called HobbyLand and it has a 320 meter track, 12 meters wide. That means people fly badass planes in there.

I want to build the Old Fogey (or the Old Speedster) instead of the Flyer I had planned. I think I should be able to do it. I would do the first flights on the NutBall just in case. Even if the NB is harder to fly than the Flyer, I have been flying in a simulator for some time and I find my skills very decent. I handle control reversing alright, coordinated turns, landings, aircraft orientation and stalls. Do you think I should go for it? Of I crash it the damage is going to be probably a broken prop and a sheet of foam.

The other option is NutBall, then Flyer and the Old Fogey and try the Flyer first.
 
#16
hey ivan, if you havent ordered yet, you might want to look at getting a smal 800 - 1300mah 3s battery. they will work with your nutball, but it'll give it more punch, (so start with the 2s then move up to the 3s) it'll help if you want to build something a bit bigger or sportier like the bloody wonder, it flies well on the 2s, but its a real blast on the 3s... anyway, just a thought.
 

ivan747

Junior Member
#17
Hi Eagle.

Well, I already ordered. I changed the order for two 800mAh 2S. I didn't like the experience of ordering though HobbyKing, their cart system and ordering system didn't inspire confidence in me. Next time I will try Horizon.

I will order some 3S in the future, along with extra servos for new planes and maybe a beefier motor. I ordered a 110W one with some decent thrust at 2S voltages, even better than the 24 gram HexTronik recommended by FliteTest. The weight tax of all of this will not exceed 50g.

By the way, I realized this whole thread could have been in the Beginner section :/
 
#18
Ivan, you should be ok with heavier and faster electronics combos for the FT Flyer. I am currently running a HB2806 1650kv motor, 30A ESC and a 3C 2200mah battery with a 7x4 or a 7x6 prop and it works magically. I have a 3C 1000mah battery I can use but I actually prefer the heavier battery.

I also used a lot of hot glue and bamboo skewers with tape along all of the leading edges so it's much heavier and there is still no problem flying.

Hope that helps!