Built an EDF composite ARF Rookie gen 1 plane. Has a 120 mm ramtec fan, big screamer motor, 200 amp jetti esc, plane was maiden on sunday. Flew for 3-3.5 min but we would like to extend the flight time to 5-6 min. Would it be best to add more cells such as going up to 15-16 cells or go with more mah batteries? the current batteries use for first flight were 5500 in 12s configuration. Any advice or ideas would be greatly appreciated. Thank you in advance.

More {mah} will help flight time.. 6600 or 7600 mah will give you 2 more minutes.. more weight also.. If you wanna sell your 5500 12s batterys ,shoot me a price and brand...

Like thay say there is no free lunch.

More power less flight time, and viceversa,.

Power is in relation to the mass of the plane, so more wheight more power needed.

Increasing capacity icreases the wheight so think this is not the way.

So possible solutions

1. A more eficient motor,(expensive and think there are only two option scorpion, and litlescreamer)
2. Wait for the new contrrolles that will handle more cells, so more voltage less amp draw and needs less capacity batteries.
3. Reduce wheight of plane, 10 cells instead of 12,
4. Proper throtle managment.

Almost sure that probably 3 and 4 can give a extra minute.

Cheers,

Juan

Juan the little screamer is for 70 mm fan. the esc i have is rated for up to 16S. The plane weighs 19 to 20 lbs. Rappor the batteries belong to a friend can't sell them. I did find some 8000 mah battery packs.

Throttle management

Also, more battery in voltage will dissipate less heat loss.

Heavier means a little more throttle on landing approach. Be careful, not to slow her down too much

You are right about the motor this is the big brother.

To have six minutes with your battery you need to pull a max of 50 amp wich is impososible in 12S

With your info you have about 3700 watts in power and cosuming aprox 85 amp to be flying 3.5 minutes.

With the same watts on 14s you will pull 71 amps

With the same watts on 16s you will pull 62 amps

My exprience is that in normal flying you are in between 45-50% power.

Think 14s and throtle managament can do the trick in 5000mah lipo.

Experiment with diferente setups before buying lipos.

Get rid of the Ramtec. It's very amp hungry.

It pulled 98 amp during the flight.

How do you figure that?? Have you run both the Ramtec and Dynamax rotors side by side and measured everything? I have... The Ramtec is faster in the air, its more pitchy and when it used to run with the OS91 it revved a little lower than the Dynamax but was faster in the air, ask anyone who has run the two. With electric its important to pick the correct motor to suit the fan and the ramtec with the correct motor is a great performer.

Yep, agreed gi mme a Ramtec any day I have been using them for 25 years and no complaint.

thanks.. were did you locate 8000mah batterys??

ramtec was a big improvement .

All true.

However - it was faster and loaded down the glow engine because it's got a higher pitch blade, that increases the amps over anything else.

Rapptor found them on hobby king web sight

How do you figure this? Oh use the same electric motor from a Dynamax right? Or you could use the correct Kv motor that matches the fan and obtain the level of performance you want.
So the efficiency of the rotor is not in question then? in that case there is no arguement about pulling more amps, the HET fan pulls more amps than the wemo minifan, it also produces more thrust and more speed in the air when using the same motor, drop the Kv and you can bring the amp draw and performance in line.

Just get yourself a quad of 4000mah 6s packs, put them in series parallel, the only issue is the charging of 4 packs instead of 2 but with the chargers available these days you can do all 4 on a DUO charger in an hour or less anyway.

In the next day or two will post the video of the maiden flight.

Pictures of the jet. Still working on the video upload.

Hi!
Do you have some video ready, this project is very exciting.

Regards
Sejenssen

http://www.youtube.com/watch?v=D6ui1...x=1&playnext=1

http://www.youtube.com/watch?v=7ShRc..._order&list=UL