8S lipo setup extreme flight extra 78"

[remie]

I hope to recieve my extreme flight extra 78" very soon.
Now I'm looking for a powerfull en lightweight setup for it.

Now there are 2 different options for me, 8s or 10s lipo.
the two big differences between those two is the rtf weight.
With 10s the total estimated weight would be somewhere arround 5kg, on 8s that would be somewhere arround 4,5kg.

I've got the following in mind for a 8s setup, but I don't know if it's is going to work.
I calculated a few things with the calculator on the Castle Creations site
sie picture at the end of this post.

The motor I used to calculate is the Neu 1513 F3A with gear reduction of 6,7 :1.
I used a 22x12 APC prop in the calculator (will run something like a mejzlik CF prop for real)

The calculator shows that the thrust would be around 10kg, if this is right that would be very nice.
On a other calculator ( this one http://adamone.rchomepage.com/calc_motor.htm) showed it only wil produce 7.1kg thrust.

The specs. of the Neu motor states that it can produce 2500watt.

does anybody of you have any experience with this setup and this motor, ore do you have any advice for me?

kind regards remie

http://i536.photobucket.com/albums/ff328/remieknaapen/poweranalyze8sextremeflight78extra.jpg

[Jeffery]

The F3A motors are designed to run on 10S, so the Kv is going to be a little low for 8S. That's why you have to plug in a 22" prop to get the power up, but I'm not sure that a 22" prop will clear on this plane. Other than that, it looks like a good match and you could always go to 10S if you weren't happy with 8S.

[remie]

The plane will clear if I'm right.

I think the kv should be oke, I compared it with the hacker C50 12XL w/6.7:1, and it almost has the same kv and they recomend 8s for it with a 22x12 prop.

would the thust that I calculated with the CC calc. be accurate?

kind regards remie

[Jeffery]

I don't have a clue, I've never measured the static thrust on a plane and don't really know how accurately the thrust is calculated in the program. I know that Gary Wright was a fan of dropping down a couple of cells and turning a larger prop for 3D, so my guess is this will be good for 3D flying.

[wingster]

Your pitch speed is only 60mph.! Also the total energy content for the 8s setup is going to limit the length of the flight. A 10S-5000mah setup in a ten to eleven pound pattern plane results in flights of approx 8 minutes. You can find some info here http://electric-f3a.com/smf/index.php?topic=41.0

[twest]

I am working on an 8s setup for a similar plane. I wanted 8s instead of 10s because I will be able to charge all the cells with one charger (instead of charging 2 5s packs).

I'm using a 3-turn version of the astro 60 geared, the specs are great, as with all good geared inrunners, but this one can be rear-mounted like an outrunner.

This is a custom wind where you order the 860gm, and request 3-turns. The specs are:

kv: 750
I0: 1.5 amps
rm: .025
gearbox: 3.1:1

I've run it on 8s 5000s and an apc wide-blade 20-12, and it drew 75 amps, 5800 rpm. I've read that the apc-e 20-13 actually draws less amps, so I might try that next for more pitch speed.
This setup works really well in the stand and I'll be test flying the plane soon. The noise is pleasant: hardly any gearbox noise, just whooshing prop sound.

[remie]

that looks very interesting!
what kind of flight times are you expecting? and what kind of thust do you have?

kind regards remie

[kmp647]

an outrunner with a kv of 300 is a good 8s motor
such as hyperion z4035 http://www.allerc.com/product_info.php?products_id=4603

you will only be able to spin 18" prop max though :rolleyes:

[bigbobed]

I'm flying an Extreme Flight 74" Yak on 8s. AXI 5320-28, CC HV85. Started with an APCe19x12w. Flew fine but the pitch speed is a little fast for my taste. Tried an APCe 22x10 and an xoar 21x8. Both have decent vertical but the 21x8 only pulls 37a wot so I'm using it. Not 3d power, but fine for sport flying.

[GWRIGHT]

Although somewhat accurate, that's a bit out of context. You need a certain amount of prop to efficiently deliver enough thrust for 3D for a given aircraft.Given a certain KV motor, it can be beneficial to drop voltage in order to increase prop size,.. extremely beneficial. However, if you can go to a lower KV motor and spin the larger prop on the same, or more voltage, that is better still. The original plane that resulted in the lower voltage and larger prop scenario, was with the acceptance that i was going to use that specific motor. In later examples of that plane (I've build MANY of my E3D XL's <G>), I've drastically increased voltage from 20 round cells, to 7S, then 10S,.. but with different motors, thus allowing the larger prop on higher voltages.

[
QUOTE=Jeffery]I don't have a clue, I've never measured the static thrust on a plane and don't really know how accurately the thrust is calculated in the program. I know that Gary Wright was a fan of dropping down a couple of cells and turning a larger prop for 3D, so my guess is this will be good for 3D flying.[/QUOTE]