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Stolly
09-18-2005, 05:53 AM
I have at home in a box the World Models 63'' Spitfire that I want to fly electric. These are the bits I have to go with it and I would like any comments on the performance I can expect as well as flight times.
These figures are on the model box, 7.5lb fliying weight,63'' wingspan, wing area 704 sq in. The motor is an Axi 4130/20 and I have two Kokam Li Poly Packs 3S1P 12.6 volt 3200mah wich are rated at 20c discharge rate.
The ESc is a tmm 7524-35 which is rated at continuous 75 amps and 90 amps for 5 seconds.
:rolleyes: Have I got enought motor and power suply or do I need to get a third pack.

Tweet
09-18-2005, 06:20 AM
I'm thinking about this class of warbird (H-9 Corsair or P-40).

I thought I would go 6S and use a 4130/16, which is the lower wind higher revving version of the motor you have and produce more RPMs and thrust at the expense of a higher current draw.

I would guess flight times with 3200 mah would be around ten minutes.

Stolly
09-18-2005, 08:09 AM
Thanks Tweet, ten minutes would be great is the spit performs like the real thing.

Stolly.

Tweet
09-18-2005, 04:22 PM
The main issue will be with the motor. Here as some numbers from motocalc:

6S 4130/16 APC 15x10 36A 108 ounces of thrust 6,900 RPM 750W

6S 4130/20 APC 15x10 21A 77 ounces of thrust 5,800 RPM 44oW

I have found that Motocalc typically underestimates the performance of the AXI outrunners by about 20%. Still, you can see the big difference in the windings.

I always seem to end up with the low wind motors. For the high wind motors you really need to use big props and that will probably be problematic on the Spit. In fact, 15x10 may already be too large?

Anyway, food for thought. I thought I'd pass along since I have been thinking about the same class of airplane.

And yes, a Spitfire that flies well for ten minutes will be plenty!

Stolly
09-19-2005, 09:06 AM
Thanks for all ya help Tweet. What would the result be if I got a third battery pack and packed the 3 of them into fuse because there is plenty of room.

Stolly

Geoff_Gino
09-19-2005, 10:10 AM
Hi Stolly

Here are some current readings taken this weekend:

THROTTLE POSITION

25 % = 5 amps
50% = 20 amps
75% = 30 amps
100% = 50 amps.

These are reading taken off my 60" Corsair that is using a 4130/16 motor and the same battery pack as you intend to use. Typically the bird takes off at 60% throttle and my All Up Weight is 4 Kgs (8.18 lbs)

Geoff

Geoff_Gino
09-19-2005, 10:16 AM
Hi Stolly

This is a link to a post about my Corsair's maiden flight with the plane's specs listed

Watt Flyer RC Electric Flight HQ (http://www.wattflyer.com/forums/index.php) > Electric Airplanes (http://www.wattflyer.com/forums/forumdisplay.php?f=1) > Warbird Electrics (http://www.wattflyer.com/forums/forumdisplay.php?f=50) Ready to try the electric route post #18

Geoff

Tweet
09-19-2005, 04:20 PM
Stolly,

If the battery pack is wired in series you'll have more volts, more RPM, and more thrust. I would think for this airplane you should be able to find a way to make 6S work though.

luc
09-19-2005, 09:34 PM
All my 3 H9 warbirds are with 4130/16 on 6S and 15*8 E apc
lightest battery setup is 6S1P TP 2100 prolite 310g
heaviest is 6S2P Irate 2200 650g
I use also tronic 2100 15C in 6S1P
avg consumption in flight is below 30A.

Tweet
09-19-2005, 09:50 PM
Flight times must be short on the 2100. How long? However all the data I have indicates that the setup you're recommending for the H9 warbirds (and also the 63" Spit) is spot on. Now I just have to decide which one to try. At the 60 size I like the P-40 and the Corsair. Any recommendations?

luc
09-20-2005, 06:37 AM
I would not take the Corsair as their LG was not top of the line; it has been reinforced and is ok on the P-40.
The P51 needs other retracts (I use the mech metal from FTE) and has some paint cracks showing on the cowling (problem solved on the P-40).
The T-6 is very nice and , as expected, the easier to fly.
time fly on these light setups is around 5 minutes, which is ok for me. If I put a 3S2P pack, I still make 2 flights from one pack and the plane is heavier, so I prefer to stay light, better for the LG and landing.
For Stolly
If you want to put a 4130/20, be ready to increase the S number to 8..;I don't think it is the best combo on these 8lbs warbirds, only for 3D planes.

Tweet
09-20-2005, 06:53 AM
Agree with Luc on the 4130/20...unfortunately, even though you already have this motor the 4130/16 would be better.

Luc, thanks for the tips on the H-9 warbirds. I like P-40s from childhood and will try one of those.

The Corsair is definitely a looker though. There is one hanging up at my LHS. Very nice.

Stolly
09-20-2005, 09:00 AM
Well thanks heaps to you guys for all the help.I think the 4130/16 is going to be the way I go, I will keep you posted on progress. Have any of you heard of a LN models Accord 47 and would you have any idea how I can get one in Australia.

Thanks again,
Stolly.

Stolly
09-20-2005, 10:28 AM
Here's another thought what if I go for a 3 bladed prop, say 14/9 or 13/9 , what do you guys think of this? I still want to use the 4130/20 if possible.
Thanks Stolly

Tweet
09-20-2005, 01:46 PM
Stolly,

I think the 4130/16 is the way to go for this airplane. Hopefully you can sell/find a use for the 4130/20.

The problem with the /20 is you either need to swing a huge prop or use more cells. You're swimming upstream to try to use it in your Spitfire.

I have the Accord R&R and have had good luck with it. I ditched the stock landing gear after a few hours of flying though. The nice thing about it is if flies nicely on 3S and a 4120/14. The smaller and lighter Accord 47 might fly nicely using a 2826/10. Not sure how to get it to Australia. Have you talked to Northeast Sailplanes?

Stolly
09-21-2005, 08:30 AM
To Tweet,
yeah I had one ordered from NES but the freight was twice the cost of the model so I went for a Astroflight 109 charger instead. I am now resigned to the fact I need to get a 4130/16 to fly this model, but so what I still have a brand new 20 for another project.( there is always another project)

Thanks again,
Stolly.

Tweet
09-21-2005, 10:33 AM
Yes, there is always another project (or EBay). Sorry for the news on the /20 but better now than after you put it in the airplane. I've been at the electrics for about a year and a half and only now think I have a feel for it. And on the giant scale model I am tackling I am still learning (partially electric partially just because it is giant scale).

luc
09-22-2005, 04:15 PM
Stolly
4130/20...
what you can do (on another plane) is using 3 packs of 3 cells (or 3S2P) in serie, vs 2 packs of 3 cells (or 3S2P) on your 4130/16 setup.
As such you will not dedicate specific expensive batteries for this unit only.
that will give you 6S or 6S2P for the 4130/16 setup
and 9S or 9S2P for the 4130 setup...

tahustvedt
12-27-2005, 10:55 PM
The 4130/20 motor works really well with 8S and a 17x8 APCe prop. This combo will also swing a 3-blade 16x10 Master Airscrew prop at ~47 A at full throttle, giving 4.4 kg (9.7 lbs) of thrust.

Electroman7
12-29-2005, 06:41 PM
I've got a world models 60 size spitfire converted to electric. It was origionally powered by a saito .91. What I'm using is an Astro 60 motor, with Astro 204 ESC running direct drive on a 9s2p pack rated at 5000 mah. The prop I use is a 14x8 3 blade. Full power pulls 30 amps for 1015 watts. The spitfire weighs 9 pounds. I tied it to a digital fish scale and at full throttle, the scale reads 9.5 pounds thrust. Top speed is about 70 mph. Full throttle will last about 9 minutes. Usually last for over 12 minutes varying throttle. Good climbout, good maneuverability. Tricky to land as main gear are not forward enough due to retracts placement.

luc
12-30-2005, 08:00 AM
yep, I got this WM 60" spit....didn't last long as flight was tricky...On a semi-hard landing, both struts went thru the wings ...and it was only semi hard...
H9 planes are much easier to fly