Katana 1.40 - RC Groups
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Jun 02, 2004, 12:11 AM
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Katana 1.40

I am looking for an awsome power setup for the cheif aircraft Katana. I was playing with moto calc and found the b5014xl with 30 cells or a 8s4p on a 20X12 prop was a good combo. My ? is, is this the best motor and can it handle 30 cells. I would like to stay with one motor.
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Jun 02, 2004, 12:24 AM
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From a thread a while ago when I was trying to figure out how to electrify it:

"are you looking for a cheap solution? If not, a Hacker B50-14XL, 5.2, 17x10 and 24 cells should power this plane pretty well but it depends on the AUW. I had a 70" Extra powered with this system. It is now being powered with Lipos and flies extremely well.
-- Kyle"

This was in reference to a H9 Cap 232 72 incher... so I'm assuming it would be fine for this one as well....
Jun 02, 2004, 12:28 AM
Suspended Account
Ah, and a fellow atlanta flyer had this for input:

"I was just running some numbers on this setup. If you only wanted sport flying, you could power it with a Mega 22/30/2 geared 4.6 in a MEC Superbox swinging a 16X10 on 19 2600's. This would give you just over one to one and keep your amps around 58.

Here is what Motocalc predicts:
MotOpinion - Katana
1000ft above Sea Level, 29.92inHg, 80F

Motor: Mega AC 22/30/2; 1770rpm/V; 2.6A no-load; 0.014 Ohms.
Battery: Sanyo HR-SC2600; 19 cells; 2600mAh @ 1.2V; 0.004 Ohms/cell.
Speed Control: Castle Creations Phoenix 80; 0.001 Ohms; High rate.
Drive System: Model Electronics 4:1 Gearbox; 16x10 (Pconst=1.31; Tconst=0.95) geared 4.6:1 (Eff=95%).
Airframe: Giantscale Katana; 992sq.in; 146.9oz; 21.3oz/sq.ft; Cd=0.049; Cl=0.45; Clopt=0.58; Clmax=1.11.
Stats: 116 W/lb in; 99 W/lb out; 23mph stall; 32mph opt @ 54% (24:26, 108F); 37mph level @ 60% (20:39, 111F); 1976ft/min @ 44.3; -294ft/min @ -6.

Power System Notes:

The full-throttle motor current at the best lift-to-drag ratio airspeed (55.4A) falls between the motor's maximum efficiency current (52.5A) and its current at theoretical maximum output (532.3A), thus making effective use of the motor.
The voltage (18.3V) exceeds 12V. Be sure the speed control is rated for at least the number of cells specified above.

Aerodynamic Notes:

The static pitch speed (63mph) is within the range of approximately 2.5 to 3 times the model's stall speed (23mph), which is considered ideal for good performance.
With a wing loading of 21.3oz/sq.ft, a model of this size will have trainer-like flying characteristics. It would make an ideal trainer, for use in calm to light wind conditions.
The static thrust (158.3oz) to weight (146.9oz) ratio is 1.08:1, which will result in extremely short take-off runs, no difficulty taking off from grass surfaces (assuming sufficiently large wheels), and vertical climb-outs. This model will probably be able to perform a hover or torque roll.
At the best lift-to-drag ratio airspeed, the excess-thrust (98.6oz) to weight (146.9oz) ratio is 0.67:1, which will give steep climbs and excellent acceleration. This model should be able to do consecutive loops, and has sufficient in-flight thrust for almost any aerobatic maneuver."
Jun 02, 2004, 12:37 AM
Registered User
Yeah I did find the thread and I guess Ill just have to wait till i get the plane from you at seff and total the weight of everything
Last edited by MagicFlyer; Jun 02, 2004 at 12:54 AM.
Jun 02, 2004, 02:15 AM
Registered User
kmashima's Avatar
If the plane is a 140 size, then the power system won't be enough. Do you know the weight that they spec? I would assume that this plane is around 12lbs+ for glow.

In any case, if it is a 140 sized plane then you want a C50-14XL, 6.7:1, 10s3p or 10s4p Lipo, and a 22x12 APCe prop. You'll have a 2400 watt system and excellent performance.

-- Kyle
Jun 02, 2004, 03:19 AM
310mph Kolibri T25 Swist
henke's Avatar
C50 14XL 6.7:1 APCE 20x13 on 30x2600 gave very good sportflying capabilities for my 14lb 1/4scale extra. no 3D but 8min of aerobatics. ~1700watts in. very mild setup for this motor.
Jun 02, 2004, 09:37 AM
Registered User
The plane is 11-11.5 lbs glow and I found in another thread where the owner said the naked airframe weigh 92 ozs.
Jun 02, 2004, 09:47 AM
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That's about 5 3/4 pounds? Not far off.. The problem is the cowl is heavy (i think), and the gear is almost a pound by itself, so carbon gear would work better and save loads of weight... I don't think there's too much else that could be done, but between carbon LG and making a plastic cowl (strech method over the current cowl) I think you'd hit under 5 pounds easy...

Jun 02, 2004, 10:16 AM
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kmashima's Avatar
so the setup I suggest would be perfect. You'll have ballistic performance - more than 200 watts per pound.

-- Kyle
Jun 02, 2004, 10:31 AM
Registered User
Would 30 cells work on that same setup Kyle and how many amps would it draw for the lipos. Would it be possible to use like an 8s pack.
Jun 02, 2004, 10:39 AM
Registered User
One more thing, would it be possible to use the acro 12xl and 8s4p to save on weight. I would like to stay with those batts if possible. I cant find the c50 in motocalc.
Jun 02, 2004, 09:44 PM
Husband, Dad, Skydiver, RC'r
Bill K.'s Avatar
Originally Posted by kmashima
If the plane is a 140 size, then the power system won't be enough. Do you know the weight that they spec? I would assume that this plane is around 12lbs+ for glow.

In any case, if it is a 140 sized plane then you want a C50-14XL, 6.7:1, 10s3p or 10s4p Lipo, and a 22x12 APCe prop. You'll have a 2400 watt system and excellent performance.

-- Kyle

Would this plane 3D on that setup?


Bill K.
Jun 02, 2004, 09:48 PM
Registered User
kmashima's Avatar
You can estimate the C50XL with a B50XL. The issues is watts = volts x amps. It's always more efficient to get the watts from more volts and less amps since the amps tend to turn into heat. It will be a matter of how much power you want. If the model is 12lbs and you want 150 watts per pound then = 1800 watts. 8s = about 4v per cell = 32 or more like 30 volts. 1800 watts/30 volts = 60 amps. This is well within the limits of a 4p pack. How much power you want is a matter of expectations. I don't know what you fly. You can also fly this with 30 cells. It should work OK.

My 3W Xtrafun is 12 lbs and 80 inches. I flew it initially with 30 cells and then with a 10s4p setup. It flies very well. You can pull out of low hovers with no problems. It is also generating more like 2300 watts or almost 200 watts per pound.

The problem with an aerobatic plane is that you need both pitch speed and thrust so you can't trade them off like you can with a pure 3D, fat wing, low wing loading plane that doesn't need to fly very fast. These planes can be gears for big slow turning props for max thrust. So the watts per pound can be much lower and still be good flying.

-- Kyle
Jun 02, 2004, 09:59 PM
Husband, Dad, Skydiver, RC'r
Bill K.'s Avatar

What would you recommend for this plane:

It's bigger brother also:

Would you do the smaller one on a B50-XL something? It's 7-9 LBS, and the bigger one says 11 to 12 LBS...

Sorry to keep coming back, just trying to learn, hoping to start on something in this range soon...

Jun 02, 2004, 10:03 PM
Extra 330L
Rob Honeycutt's Avatar
a lot of the planes that chief has are the same as giant scale planes.com like the katana.. I noticed that they were pretty heavy when I saw them at a show last year...

The new electric funtana 140 size is supposed to be out this month sometime and I would hope it might be nice and light? It is purple and white like gary wright's model and ready for a hacker!

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