Posts: 742
Joined: 8/25/2003 From: Fort Collins, CO, USA Status: offline
This is a series of 4 posts so please don't reply until done.
First I have to give my overall impression of the Mini Katana ARF which is WOW! I believe this is a Gen 2 kit. The light strong construction is amazing. The wing was impressive with the capped ribs and the CF tube support, and the use of CF in the fusalage was truly innovative. I was moving the stuff from my Mini Funtana into it so the setup is:
AXI 2808/24 TP 2100 Gen II HS 55's Electron 6 Jeti Controller AUW (with mods) 27.6 oz CG 88mm from leading edge
Ok, what to change. After reading a couple long threads at RC Groups and looking over the kit, I knew I wanted to make some mods:
1) While the CF Landing gear in the Gen 2 was strong enough it provided little give, so I bought the aluminum gear from 3Dhobbyshop.com. This adds almost an ounce, but it is a nice gear.
2) Increase the size of the rudder and add a tail wheel.
3) Put in a magnetic latch and a spot for the aileron wires to run.
4) Deal with mounting the AXI 2808/24, the cage mount did not look strong enough. It has balsa tops and I knew length was going to be a problem.
Before I start these mods, let me make some comments on overall confusing things in the build.
A) The cowl is designed to just touch the front of the hatch it does not overlap it like on the Mini Funtana. It says this in the directions, but I struggled with this for a while before getting a clue. Trying to overlap it is difficult, and involves redoing the front of the hatch.
B) Be sure and inspect and reglue any spots that might not have gotten enough, or got loose during shipment. It is just a good idea to take some thick CA and go over the joints on the front firewall and landing gear. (My kit arrived in really good shape, so I don't want to give the impression there was a problem)
C) The battery location is confusing. After reading all the posts I was conviced the battery was going to be mounted above the spar so I would need to make a platform for it. But, as it turns out to get the right CG (88MM) I had to put a portion of the battery through the front firewall into the cage. See picture.
< Message edited by lwatson -- 3/4/2006 4:22:39 PM >
Posts: 742
Joined: 8/25/2003 From: Fort Collins, CO, USA Status: offline
Next lets talk about rudder mods.
1) I added a little to the top the rudder and back of the rudder using 1/8 inch balsa, that is a little thinner than the actual rudder but it ended up looking OK, I have heard on Gen 3 they are going to enlarge the rudder.
2) Added a tail wheel. I used a Eflight 3D control horn as a support piece, worked well.
3) Beveled the edges on the hinge edges on the rudder and elevator. Without doing this you need to leave a 1/8 gap to get good throws, I didn't like that. My gaps are more like 1/32".
Posts: 495
Joined: 1/24/2005 From: Derby,
KS, USA Status: offline
The cowl overlaps the piece of balsa on the front of the fuselage, but that's it.
The motor cage is plenty strong. You mount the motor behind the firewall, not in front of it. I made the same mistake. I did add a piece of ply along the bottom though, and it had no give and survived heavy snap rolls.
The battery should slide into the cage for the right CG too.
Posts: 742
Joined: 8/25/2003 From: Fort Collins, CO, USA Status: offline
Next was a spot to run the aileron wire through and a magnetic latch. I think they should fix this, the current screw latch mounting and putting a raw hole through covering kind of sucks.
I also incorporated a spot to put my receiver, because the HS-55 servos are in the tail and a 6" extention will not reach to the location they suggest.
Posts: 742
Joined: 8/25/2003 From: Fort Collins, CO, USA Status: offline
Next was the motor mounting. In the mini-Funtana I built my own, and while some have had luck with a reinforced cage mount. I just really liked this approach.
1) I got the AXI aluminum stick mount from espritmodel.com. The mount needs to be adjusted a little in that there is a O ring that needs a little more space to turn on the back of the AXI2808 so you need to make room for it. Also the back needs countersinking for the screws.
2) The mount fits a 10MM stick, so you have to add some 1/32" ply shims to get a 3/8" birch rod to work. (The model comes with a balsa stick mount, I did not even consider it)
3) Then you can cut the standard mount to support the stick mount. I just think the result is really clean. It gives all the right thrust lines and its length is adjustable.
< Message edited by lwatson -- 3/4/2006 4:29:17 PM >
Posts: 742
Joined: 8/25/2003 From: Fort Collins, CO, USA Status: offline
I madiened the Mini Katana today. Wind was a little choppy so I only got 2 flights. Greased in two dead stick landings, so I am pretty happy so far. Have not had a chance to mix in anything yet, so I am interested in others experience. It mentions some suggested mixes in the instructions but it was pretty cryptic. Advise?
Posts: 1776
Joined: 9/17/2003 From: Hilton Head Island,
SC, USA Status: offline
lwatson,
I don't know why the Katana Mini has not taken off on RCU like it has on RCG, but maybe we can get this thread going here. I have had a few Katana Minis (a couple pre-production prototypes and a gen 1) These are awesome little planes that fly very similar to a GS plane. Make sure you have the plane ballanced laterally and that your thrust angles are set to where the plane tracks straight on vertical lines. I think alot of people skip these two steps and end up with an inconsistent flying plane. We also mix in flaperons but don't use it much.
We'll be testing the new PA CF gearboxes in the next week or two and anyone going to SEFF this year is welcome to demo one of the planes.
I'll post pics of the GB and install here If you don't mind me jumping in on your thread.
Posts: 94
Joined: 12/27/2002 From: Albuquerque,
NM, USA Status: offline
Hi Guys,
I hope that you don't mind my adding to this thread, but I would like to show some photos of my structural improvement to the Katana Mini fuselage and also what I had to do to get the C.G. right on my model.
First and second pictures show a 1/16 x 1/2 sheet balsa strip I added to the fuelage diagonal truss adjacent to the wing trailing edge area. The original truss has the grain going parallel to the thrust line and is subject to splitting if you are a little heavy-handed when installing the hatch on the fuselage. Adding the balsa strip provides strength to this area at a negligible weight increase.
Third and fourth pictures show the placement of my receiver, ESC and LiPol battery. I had to move these components as far forward as I could to get the C.G. to 3 1/2 inches aft of the leading edge at the wing root. My plane has a Hacker A30 outrunner motor, a Hacker X-30 ESC, a HiTec Electron 6 receiver and HS-55 servos, and a 3 cell 950 mah battery pack. Considering that the model is an ARF and required only assembly with no building, I was at a loss as to why I had to locate these components so far forward. Would welcome any ideas or comments on this.
Posts: 495
Joined: 1/24/2005 From: Derby,
KS, USA Status: offline
You can't be serious that you're using a 950 mAh pack. You need at least 2000mAh if you want good flight time and a battery capable of handling the amp loads.
Posts: 94
Joined: 12/27/2002 From: Albuquerque,
NM, USA Status: offline
Hi RyGuy,
Thanks for the info on using a 2000 mAh battery. Apparantly my C.G. problem was due to the weight of the 950 mAh battery I planned on using. Incidentally, I was serious about using this battery as my past experience has only been with flying a hopped-up GWS Slow Stick equipped with ailerons, a brushless motor and the 950 mAh Lipol battery. It was fine for that application and in my ignorance, I thought it would be O.K. for the Katana Mini! Oh well.....live and learn! Next stop will be the local hobby shop to buy a 3 cell 2000 mAh Lipol battery. Also, what diameter/pitch/brand prop would you recommend for my set up?
Posts: 742
Joined: 8/25/2003 From: Fort Collins, CO, USA Status: offline
If that is the Hacker A30-16M you should try a 12X6E prop a, 11X7E prop, and a 11X5.5E prop. You can try a 12X6 SF, but that is going to really suck a lot of amps, and lower your flight time. It is best to measure the amps.
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Mini Katana Mods - 
