3D Hobby Shop 55" Katana LIVE Build Log - Page 3 - RC Groups
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Oct 03, 2007, 12:50 PM
Registered User

Now, a word about power.

Power on this bird is going to be a bit on the wild side.

When I was flying with Ben out at his shop, he suggested the idea of a 9S power system for the 55" planes. By upping the voltage, we figured it would be possible to drop the current draw substantially and still maintain good power. Then, you could just use 3 packs of 3S 2100s wired up in series to make a 9S pack - no new batteries needed - just fly your 55" on 3 of the packs you fly the 47" with.

And so I hunted down a motor that would do the trick. No details yet, but it's in our E60 class, and spinning a 15X4, it makes 9+ pounds of thrust on just over 30A. That's 930W - should be enough to fly the plane just fine. My only possible concern is whether the prop will offer up enough speed to do the trick - static pitch speed is just under 40 mph. That should be enough, but we'll see. If I end up needing more speed, I can swap over to the 15X6, which makes almost as much thrust, but pushes 60 in static pitch speed. Current goes up to around 42A in that case.

So the setup will be:
Prototype CSRC E60 with a super-secret special wind
9S1P CSRC 2100mAh (3 3S packs in series)

Should be pretty much giant foamie-style power - gobs of thrust and not much speed. I think that will do nicely on this machine.
Last edited by Jeremy Sebens; Oct 03, 2007 at 02:26 PM.
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Oct 03, 2007, 12:55 PM
ExtremeFlight - 3DHS - Legacy
blucor basher's Avatar
14x6 sounds good, too. Really looking forward to seeing this setup fly.
Oct 03, 2007, 01:00 PM
Registered User
If I had just listened to your servo recommendation, I'd already have posted video by now... (beats forehead with aluminum servo arm)

The weather is taunting me - sunny, very little wind. It's saying: "Shouldn't you be doing a maiden flight today? Oh yeah, that's right, you were stupid and didn't buy the right servos for your plane..."
Oct 03, 2007, 01:41 PM
Test your skills....fly IMAC!!
sun.flyer's Avatar
Originally Posted by Jeremy Sebens
The weather is taunting me - sunny, very little wind. It's saying: "Shouldn't you be doing a maiden flight today? Oh yeah, that's right, you were stupid and didn't buy the right servos for your plane..."

It's alright young Jeremy, we all live and learn. 9s huh....... yeap sounds like something Ben would recommend on a 55" airplane. However your posted watts numbers look very similiar to what I am sure most are seeing on there 55" Extra SHP's (if you can call that normal on a 5 lb. or less airplane).

Oct 03, 2007, 01:55 PM
Extremely Twisted
cwojcik's Avatar
Regarding the gap on the stabilizer...

I've noticed this on a lot of ARF's. Is it there as "wiggle room" to allow for alignment of the stab? I'd rather need to use some thick glue to hold it in than have it stuck out of alignment.

Gorgeous airplane, also.
Oct 03, 2007, 02:25 PM
Registered User
It's really not that much of a gap - I was just being picky.

And yeah, you're right - it's nice to have a bit of wiggle room.
Oct 03, 2007, 02:30 PM
Team 3DHS
BoneDoc's Avatar
That's it??? You're going to leave us hanging like that?
Oct 03, 2007, 03:40 PM
Registered User
Drive some mini servos over here, and I'll have it in the air in a couple of hours! It's no fun living in a town without a real hobby shop. We've got a little shop here, but it doesn't offer much support for electrics or smaller stuff.

Here are a few glamour shots in the sunshine (sans tail linkages) so you can see how purty she is...
Oct 03, 2007, 05:06 PM
Test your skills....fly IMAC!!
sun.flyer's Avatar

Great looking Kat!! I remember how sweeeet this plane flew down at SEFF this year. Can't wait to get my hands on one as well. Should be a real hoot!!

Oct 03, 2007, 06:13 PM
Team 3DHS
BoneDoc's Avatar
I drive over to Fredericksburg all the time .
Oct 03, 2007, 10:27 PM
Use the 4S Luke
feathermerchant's Avatar
WooHoo Jeremy looks great. I learned a while ago to 'Trust the Aggie Engineer'
I just don't ask anymore. I even bought his power system for this one. My LHS was out of the analog servos so I used 5245's in the tail too. All I need is a spinner so I can center up and intsall the cowl then seal the hinge lines.
Oct 03, 2007, 11:15 PM
I used to be all thumbs...
NumbSkull's Avatar
Well, I was wondering where the build thread was for this one. It's almost out, and I hadn't seen much about it....

It looks great, but I wouldn't expect anything else from 3DH.

Been on the fence on this one, but after seeing a few pics... well lets just say the card is coming out...

Cant wait to see some video!!
Oct 04, 2007, 11:22 AM
Registered User
Servos are on the UPS truck on the way to my house now - not sure when they'll get here - sometimes I'm late in the loop.

As soon as they show up, they go on the plane...
Oct 04, 2007, 01:44 PM
Use the 4S Luke
feathermerchant's Avatar
Got Spinner. Cowl is installed. Final control check, CG check, Velcro then pack it away.
Oct 04, 2007, 03:43 PM
I used to be all thumbs...
NumbSkull's Avatar
What size spinner are you guys useing for this one?

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