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        Build Log 3D Hobby Shop 55" Katana LIVE Build Log

#1 Jeremy Sebens Oct 02, 2007 08:54 PM

3D Hobby Shop 55" Katana LIVE Build Log
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In one of my phone conversations with Ben at 3DHobbyShop, while we were discussing some more wacky power system thoughts, he managed to twist my arm and convince me to take early delivery of my 55" Katana. I decided to take one for the team, and will be presenting a detailed build thread here. There's no manual as a result of the early delivery, so this thread may differ from the manual a bit.

Power is going to be a CSRC prototype system, and it will be a bit on the wild side - more on that later!
EDIT: Here are the items I'm going to be running in the power system:
Prototype CSRC E60
9S 1P CSRC 2100mAh (3 3S packs in series)
More details on page 3.

This will be a "live" build thread - I'll be working through the night, and will post photos and comments as each step gets completed. So toss some popcorn in the microwave, hit the subscribe button, and stay up as long as you can. I expect this will involve some burning of the midnight oil, but that's become a sort of ritual with me for any new plane anyway.

As usual, the plane arrived triple boxed, and everything came through just fine. As with all of my UPS shipments lately, it looked as though it had been through a coal mine, but it didn't appear to have been mishandled or stomped upon.

Anyway, let's start things off with a couple of kit pictures:

#2 Jeremy Sebens Oct 02, 2007 09:07 PM

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My next ritual with new planes is to weigh in the airframe. I'm not really very religious about weighing individual parts unless I'm designing the plane, so this will just be a few mass weighings.

Here's the weight sheet I came up with:
Fuselage (w/ canopy):12.3 oz
Wings and tail surfaces: 14.95 oz
Cowl and wheel pants: 3.2 oz
Wing joiner, landing gear, and hardware pack: 7.35 oz
TOTAL: 37.8 oz (2 lb, 5.8 oz)

That's just about as light as I can imagine an airframe this size coming in at and staying together. COOL.

#3 CatchmyCorsair Oct 02, 2007 09:20 PM

Lookin good! The covering scheme looks very nice and I like the slicked back canopy.

This is the largest plane I can fit in my car. :)

#4 Jeremy Sebens Oct 02, 2007 09:29 PM

Fuselage walkthrough
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Taking a look at the fuse, I see a lot of well-thought-out stuff.

First off, it just looks good... :D But here are some other nice points:

-Spiffy giant-scale-style motor box, with a doubled firewall.

-Preinstalled handy-dandy hatch latch

-Extended tabs for cowl mounting

-Lots of room to slide that battery pack forward - in fact, you can go all the way to the firewall!

-Option of mounting rudder servo in the tail or up front for pull-pull. I'll build the plane complete except for the rudder linkage first, check balance, and then decide where to put it. But I have a feeling it's going to be a pull-pull setup.

-Lots of formers. I think one of Ben's design rules must be "If you think you have too many formers, add two more." This is a good thing. Formers=torsional stiffness.

#5 Neil Morse Oct 02, 2007 09:30 PM

Is it done yet? :D

If this bird flies anything like the 55" Extra SHP, you will absolutely love it.


#6 Jeremy Sebens Oct 02, 2007 09:33 PM


Originally Posted by Neil Morse
Is it done yet? :D

If this bird flies anything like the 55" Extra SHP, you will absolutely love it.


It ain't even started yet! In the interest of posterity, I'm trying to document it in its pristine form before I get to cuttin' and gluin'... :D

My understanding is that it flies like the SHP, but with meaner tumbles. I can't wait to get it airborne. I'm having to seriously restrain myself from just gluing it together and getting it done. MUST... SHOOT... PICTURES...

#7 Jeremy Sebens Oct 02, 2007 09:46 PM

Wings - everybody needs 'em
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Now, on to the wings. These are nice too, and are exceptionally light, considering the large area and thin-section airfoil.

Nice things I noticed:

- REAL Katana chamfers (some folks call them fillets, but they're chamfers!). No cheating and leaving off the front or back of the "strake" shape.

- THIN airfoil. This is what gives 3DH planes their easy harrier transitions.

- As always with 3DH, the hinges are preglued into the control surface.

- Pocketed servo bays - the ply that the servo mounts to is recessed below the sheeting. For those of you like me that want to run standard-profile servos in the wing, it looks like there's enough wood to make the trimming possible and still have enough structure left. EDIT: It looks like we might be a bit shy on depth for standard-height servos. We'll see...

- Also as usual, there's a little plywood tab tacked to the structure to hold the string that you'll pull your servo extension with.

#8 sukhoi26mx Oct 02, 2007 09:51 PM

Looks great Jeremy! You're going to love it. I think Ben hit the nail on the head when he called it "brutal" - loves to be flown hard. Should be a perfect match!


#9 Jeremy Sebens Oct 02, 2007 09:54 PM

Time to look at some tail...
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The tail surfaces are up to snuff as well.

The horizontal is an airfoiled surface, with the stab being fully sheeted and the elevators open-frame except for the sheeted counterbalances. Again, we're looking at a nice thin airfoil section - good for tumbling and snaps, IMO.

The rudder is lightweight, and is a bit thicker - this is a wise design decision - adding a bit of extra thickness to the vertical stabilizer and rudder will help tracking. Also in the good category: the rudder has a moderately thick (~2.5mm) trailing edge. This helps yaw stability at higher speeds, and adds a bit of downline drag.

#10 Jeremy Sebens Oct 02, 2007 10:17 PM

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One last pre-build nice thing.

The cowl ships with a cardboard insert to keep it from getting crushed/warped in shipping. It's a little thing, but it's a nice thing.

#11 blucor basher Oct 02, 2007 10:22 PM

This helps yaw stability at higher speeds, and adds a bit of downline drag.

Also helps when bashed against a car door or trunk!

#12 CatchmyCorsair Oct 02, 2007 10:24 PM


Originally Posted by blucor basher
This helps yaw stability at higher speeds, and adds a bit of downline drag.

Also helps when bashed against a car door or trunk!

Or gets chewed by the cat.

As me how I know... :rolleyes: :eek:

#13 Argyle Oct 02, 2007 10:27 PM

Sexy plane. That might be the best ARF covering job I've ever seen. I want one.

#14 blucor basher Oct 02, 2007 10:28 PM

You have one of those cats too, eh? Ask me why the cat is still alive after chewing one-of-a-kind prototypes. Because it's my wife's cat, that's why.

#15 Joe_Curd Oct 02, 2007 10:33 PM

I have a cat that has lived a long life due to my wife. I completely sympathize. He eats Prozac now.

I cant wait to see Jeremy fly this thing. It's gonna be sick.


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