Electrifying a Neptune Seaplane - help please! - Page 6 - RC Groups
Thread Tools
Jan 25, 2010, 08:21 PM
Registered User
fairplane's Avatar
Originally Posted by tuppertn
That's a whole thread in itself, bro.

Basically, once you determine how many watts you need based on the plane's weight and desired performance, you have to figure out the best way to get those watts. Since watts = amps x volts, the higher the voltage you use the fewer amps you need to draw to get the same power consumption. You can get 1000W from a 3S setup (~11.1v) but you need to draw 90A to do that. Using higher voltage is a more efficient way of using electricity (ie - it reduces loses due to resistence). So it's more efficient to get those 1000W from a 5S (18.5v), 6S (22.2v) or even 8S (29.6v) setup drawing only 54A, 45A or 34A respectively.

So it's partly a matter of preference, partly a matter of what gear you may have on hand, and partly a matter of planning for best efficiency. It may seem complex, but that complexity reflects the fantastic veratility of an electric setup. With the same motor and ESC I'm using now I could give this plane anything from 375-1500W. I can give it gobs of low-end thrust and have it launch vertically out of my hand or have a top speed over 85mph all just by changing the battery and the prop.

Well I guess I should do some number crunching and some research-maybe I can find a reasonable price to electrify rather than go glow. I know my wife would appreciate electric more than glow but mostly she would rather I not bring along any planes on our boat LOL! Thanks again for all the info and I'm sure I'll be talking to you later- Harold AKA Fairplane
Sign up now
to remove ads between posts
Apr 09, 2010, 06:14 PM
Registered User
Neptune 6S Setup Help I have (4) 3700 6 cell batteries that I want to put into a Neptune.
I have a Seamaster with a .56 Satio that I crashed. I bought the Neptune to switch things over, but then a friend looked at my Seamaster and said it could be repaired.
I want unlimited vertical climb, with reasonable flight time, I have read, and understand to some point sizing motors to planes, but electric is all new to me.
I was looking at Hobbykings Motors
Turnigy 50-55B 600 KV motor
with a 80 Amp ESC
Would this be a good combonation?
Most things I have read have been 5s setups.
Thanks in advance.
Apr 09, 2010, 10:11 PM
Postcards From The Purple Edge
tuppertn's Avatar
The 50-55B should be fine on 6S. Unfortunately, HC doesn't five any useful specs like Io and current capacity so it's difficult to make predictions. The comparable size Scorpion has a continous rating of 1500W, so if the Turnigy can cope with 1500W I would think you should be able to swing a 12x8 or 13x6.5 and expect something in the ballpark of 8-9 lbs of thrust at 22V. A wattmeter would be essential gear to be sure you weren't overtaxing the motor. 80A ESC will be fine. Personally, I wouldn't trust the BEC on 6S though. Use either a separate BEC that can handle 6S or a rx battery.

Apr 09, 2010, 11:14 PM
Registered User
I think I will go with scorpion, I have them in some Helis, and you can't go worng.
Big Sky Hobbies is having a sale as well- Castle ESC and more
You have to put it in your cart to see prices, or request a email about the sale.
Apr 10, 2010, 12:35 AM
Postcards From The Purple Edge
tuppertn's Avatar
Originally Posted by KingJoe
I think I will go with scorpion, I have them in some Helis, and you can't go wrong.
Couldn't agree more. Take a look at the 4025-10. I don't have access to ScorpionCalc right now, but I'm gonna guess that it'll spin a 14x7 on 6S for some nice numbers.

Apr 13, 2010, 02:15 PM
Registered User
cracksmeup's Avatar

sea master

Hey guys i just droped in ,if you would like to build your own and make it light here are the free down load of the plans they did for electrict.Just scroll down till you see it. joe http://plans.rcmodell.hu/plansport.html
Apr 19, 2010, 02:45 PM
Registered User
fairplane's Avatar
Hey Tuppertn- any chance you could post some deatailed photos of your Neptune? Finally decided I will go electric and would like to see how you have your battery setup and your motor/esc installation. I ordered a new charger and will order the batteries once i figure out which to use- I was thinking of going with your setup of a combo of 2s and 3s maybe 5000mah. I am only a fly for fun and don't require extreme performance so am wondering if 20c batteries are sufficient. I have never setup an electric before and I haven't really found much in so such as simple terms to easily design a system. I am thinking an 80 amp esc with an electric equivalent to a glow 46.I had saved alot of info on the Neptune and power systems but lost my hard drive and motherboard on my computer and lost all the information so now have to start all over from scratch. Once again thanks for all your help. Have you maidened your Neptune on water yet? Fairplane
Apr 19, 2010, 04:44 PM
Postcards From The Purple Edge
tuppertn's Avatar
There was a lot of trial and error fitting going on when I did mine so be warned. This is not an "electric ready" model.

I went with the 2s/3s serial setup to allow the batteries to sit through the lightening holes already cut in the native formers. I didn't want to mess too much with the plane's internal structure.

My placement of the ESC reflects what I thought would give it the most efficient cooling and keep it as dry as possible. Getting two 10AWG power leads down that skinny shoot meant for the throttle servo extension was a pain. It took a fair amount of sanding to enlarge the channel enough to feed them through. I wouldn't try this approach without the extra capacitors to protect the ESC. The airflow exit hole in the bottom rear of the cowl is actually much larger than it looks in the picture.

Okay, here you go. Good luck!

Apr 20, 2010, 02:49 PM
Registered User
fairplane's Avatar
Thanks for the pics Kendall-so basically both your batteries are in the nose-correct? And you went with the 2s and 3s combo so you wouldnt have to mod the hull? So what are the extra capacitors for-where do you get them- do they have a value/spec? Did you glue in your engine pod mount or just use a screw? How much flight time are you getting with your 4500mah setup? Once again thanks for the info-hope I'm not being too much of a pain in the-Harold
Apr 20, 2010, 09:11 PM
Postcards From The Purple Edge
tuppertn's Avatar
Originally Posted by fairplane
Thanks for the pics Kendall-so basically both your batteries are in the nose-correct? And you went with the 2s and 3s combo so you wouldnt have to mod the hull?
For proper balance and flight the bats go right where you see them in the pic--basically flanking the pylon. Up in the nose made it way too nose heavy. Putting them back through the formers was the only way to get a good CG. You could do the same with two 2s or two 3s bats for 4s or 6s configuration.
So what are the extra capacitors for-where do you get them- do they have a value/spec?
The extra caps are to protect the ESC from the voltage spikes created by the long power leads. Lots to read about it here. The ones I used are Rubycon ZLH 220uF 35V
Did you glue in your engine pod mount or just use a screw?
I just used the screw. There's really no force trying to pull the pylon up out of the plane. I did add a 3/8" square spruce brace at the bottom to reinforce the back of the box. I read somewhere that someone's plane failed right there. See pic below.
How much flight time are you getting with your 4500mah setup?
8 minutes of casual sport flying. I usually put back about 2800mAh.

Apr 27, 2010, 11:11 PM
Registered User
fairplane's Avatar
So I finally bit the bullet and ordered hopefully all I will need to electrify my Neptune. A big thanks to Tuppertn for all his help and advice. I am basically copying his setup-just with less expensive parts. I opted to go with the Turnigy TR 50-55B 600kv brushless motor
TZ85A Turnigy Brushless ESC 85A w/ 4A SBEC
2s and 3s Rhino batteries to get 5s- 4900mah 20C
13X8e performance prop
S3003 and S3004 Futaba Servos
10awg wire to extend esc to battery
Still looking for 220uF 35V capacitors to protect the esc

Now I just need to find some time to start the assembly process! Hopefully have her done for July(as we have alot of house work to do first) Will keep posting as my build progresses-Fairplane
Apr 26, 2011, 12:30 PM
jrbackus's Avatar
Ok, I know this thread is super old, but I have a question that you guys may be able to help with.

I just built a Neptune (electric) and I had to add about 2.5oz of lead to the tail to get the CG @ 4" (as per the manual). I was a little leary about this CG location as I also have a Seamaster that flys awesome with the CG in the 3-3.5 range (as per the Seamaster manual) and they're pretty much the exact same airplane. I just flew it for the first time this weekend and it flew alright, but it was acting a little strange. I couldn't tell if it was the CG, or the thrust angle, or the fact that it was gusting in the mid 20's, but something was a little "off". All I know is that it flew NOTHING like my Seamaster with a .55AX.

So where are you guys at with the CG??? If I need to move it forward, great, I can get the weight off the tail, but I figured I would get some opinions here first before I took it back out.


Apr 26, 2011, 02:38 PM
Fuzzy Member
lupy's Avatar
I have the maxford version, and I replaced the ailerons with wider ones, so my measurements my be diff than yours.
I use about 3.75", and it seems to fly fine. Mine was right at 88oz, compared to 109 oz for my seamaster. needless to say, the seamaster is way more stable in gusty wind.

The maxford NeptuneII flys way slower, takes off shorter than the seamaster, but weight means higher average speed, and more resistance to side wind, so the seamaster wins out. The neptune, with it's lighter weight, is way more fun in the calm though.

I am curious about your version of the Neptune, take a look at this thread, and see if your ailerons taper the same way mine did. It might explain some of your experiances.


Look at the pic on post 3, the stock aileron tapered faster than the airfoil, and seemed to cause problems. In light wind I don't think it was much of an issue, but with gusts, I really noticed the lack of control around center compared to the seamaster, which dosn't have this issue.
Apr 26, 2012, 10:00 PM
Registered User
fairplane's Avatar
OK-I know its been a long time, but better late than never. I had to enlist a club member to help me get my Neptune almost ready. Heres some pics. I'll post more when i get my plane back!
May 04, 2012, 09:18 PM
Registered User
Im building this plane and desperately need help with the elevator linkage. I cannot get it to work correctly. The manual I have is ridiculous.

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Electrifying a 60" Climax-help please belouder Electric Sailplanes 4 Jul 20, 2007 02:18 AM
Discussion Electrifying a 60" Climax-help please belouder Hand Launch 0 Jul 18, 2007 04:58 PM
Some help please Spin_Doctor Electric Plane Talk 1 Jul 18, 2001 10:11 PM
FMS HELP PLEASE!!!!! PunkerTFC Electric Plane Talk 6 Jul 07, 2001 05:40 PM
can anybody in Europe help please Theuns Electric Plane Talk 1 Jun 04, 2001 02:46 PM