1QwkSport2.5r

So.. The original Kamikaze was pretty successful with a .65 engine and a .90 engine. I decided to shrink that boat down, add a step to the keel, and use a .29 or .30 engine on a full tuned pipe. I'm not 100% on the step hull just yet, but it looks pretty appealing at this point. Hull size should be 26"L x 14"W x 2.5" thick at thickest part. The step will be 1/2" deep, at the middle of the hull. The rake and keel is tapered from the bow to the transom, so speed should be good. I'm planning on using 9" props, and wet rudder.

Current materials list will include:
Balsa -3/32" balsa sheet, 1/8" balsa sheet, 1/4" balsa sheet, 1/16" x 3/8" balsa strip, 1/8" x 1/4" balsa strip, 1/8" x 3/16" balsa strip
Birch - 1/32" plywood
Maple - .150" 3-ply Maple plywood (55 year old hollow door skin, very nice grain patterns)
Cherry - Various sized strips for color accent.

Rough drawing with the step added to the plans:


Side-view comparison of original Kami ".60 size" to my modified ".30 size"

Top and side view comparison, original Kami and new Kami.

1QwkSport2.5r

I cut out and assembled a (non-complete and flimsy) mock up of the new mini-kaze. 6" shorter and 4" narrower than my original ".60" sized Kamikaze. Should make for a quick boat if it even floats in the end.
Mini-kaze frame next to the drawing for the original Kamikaze. The paper is pretty flimsy so it isnt showing how wide it really is but its about 80% of the original scale.


I think it'll look pretty cool with this hanging off the back:

1QwkSport2.5r

Got some of the frame going on the Step-Kaze. This is the most tedious part of the build, cutting the pieces out. I'm assembling the frame similar to my original Kami build, notching all of the pieces so its a nice tight fit with just enough room for some epoxy in all of the joints. I am using maple plywood (1/8" 3-ply thats 55+ years old) from an old door for extra strength. The joint between the balsa and plywood will be fiberglassed together, and epoxied well. Here's the progress so far:


I might have to call this the SuperKaze since it'll have a Super Tigre engine on it like the big Kami with the big Tigre .90.

1QwkSport2.5r

Got a little more done on the framework. The transom isn't pictured, but its cut out. I have a few little diddy's to clean up on the frame, and I can start gluing it together.



Weight is maybe 2oz so far. I'm still sorting out the engine mount - not quite sure how I'm going to mount the engine stand to the hull just yet. I'm kicking around a few ideas.

1QwkSport2.5r

Got a few more pieces cut out for the radio box, and bow. Still a few more pieces to cut out for the main frame, and then I'll glue the frame and add skin support strips. I haven't weighed it yet, but Ill guess 3-5oz so far without any glue.

SFC K

Someone has been busy! It looks like a great start! I just order a FE so will have to get together when I get back!

1QwkSport2.5r

I am just burning spare time building this thing. This one won't take me 3 months to build since I learned a lot from the first attempt.

I'm a little lost with the "I just order a FE so will have to get together when I get back" bit... I thought you were deployed? Still in town for the holidays...?

SFC K

Yeah, I ordered a boat so when I get home this spring I will be able to hit the lakes too. I am still deployed, unfortunately. Time is flying by so hopefully you will have this one done too so I can check it out and shoot some videos for you!

1QwkSport2.5r

I had heard you were in town for Thanksgiving. I hope the holidays bring you joy and happiness while you're overseas. You are in my thoughts, and I thank you for your service.

This build is moving along well. I have most of the frame glued and I'm about to sand it down and glue the skin support and the skin itself. I look forward to having a boat day where the tripod does the work and we have some fun. I'll post build pics sometime in the next few days.

SFC K

Thanks, I really appreciate that!! I actually was home for 2 weeks I Sept. It went rather quickly but the weather was really nice! 80’s and 90’s for most of it.

Cool, can’t wait to see some more pictures of this one. I may have to build something that I can run the .65 K&B motor. I wonder if I could adapt a flex shaft to the output and run it that way with a rudder for steering. I thought I saw something like that on here…I will dig for it…

1QwkSport2.5r

The sportster .65 cannot be set up with a flex shaft. I had asked mecoa (the current mfg of the sportsters) if a .65 could be mounted to an outboard lower unit and he said no. You would need a custom crankshaft and backplate to use as an inboard.

Also - the carb on the target drone engines aren't calibrated right. They run too rich. Let it idle more than 2-3 seconds and it'll quit. I'm going to put a perry carb on mine, which is $50. I've tried everything to get it to throttle well. These engines were spec'd to run wot only. That's per the military contract K&B had with the military.

1QwkSport2.5r

I have a little work to do on the nose to get the right shape and contour - The plywood doesnt like compound bends, so I'm hoping to get the bow rounded just right so the plywood will lay flat and not require a "Y" cut like the big kami did. I have a backup plan if needed. First pic is a better side-by-side to the original .60/.90 sized Kami.


This is the bottom of the frame. The whole frame weighs roughly 8-10oz. Maybe less.


I have the prop line set up to be exactly 1/3 total length measured from the transom. So far, the frame balances almost perfectly on the prop line. That really surprised me.

1QwkSport2.5r

Making some headway... Current progress:




I used poplar dowels around the perimeter for strength. The bow is all balsa. So far it still balances pretty well, and weight is right around 14oz as pictured.

dadkins

Hey rcT, That is a good lookin boat so far - looks light ! Sweet pipe ! looks like it should go good !
Merry Christmas to you and your family...and to evryone here on RCU.
Dave

1QwkSport2.5r

Thanks rcD This baby gets a full pipe.. should make the engine rock!

Merry Christmas to you, and Happy early New Year!

1QwkSport2.5r

I have the bottom framing done now. I have 1 piece of hardwood I have to glue in for the trailing edge of the rake (step), but I will do that at the same time the skin goes on. Its [mostly] straight and seems strong enough to run at least once. Maybe twice. Beyond that, is anyone's guess.


I'm setting the radio box up similar to the other Kamikaze. Simple and effective.



I have the skin ribbing to do on the top, and build the engine stand. Coming along well, I think..

1QwkSport2.5r

Skin ribbing on top is done now. Whole frame is sanded down and almost ready for skin. I need to mount the electronics and get the cables glued in and soldered. Having a hard time sorting out the engine mount - I wanted to mount the engine so the weight of the engine itself is balanced to the mount, but I will probably have to use a Radial mount for that. I might mount it upright to start with and make a new mount later using a radial mount. The jury is still out on that one.

Anyway.. a pic of the progress..

1QwkSport2.5r

I havent been good about naming my boats.. My first boat was a copy of the original Kamikaze, so I just left that one original. I think, in consideration of life over the past year and its trials and tribulations, I'm going to name this boat Lady Luck. Luck doesnt have much to do with anything, IMO, but hey... what the heck..

I built the engine stand yesterday. I went the simple yet effective route on this one, and I really like it. The engine is offset 1/8" to the port side for now, to help with balancing the enormous tuned pipe.


For some reason, I'm really happy with this one.

1QwkSport2.5r

Radio box finalized and mounted. I'm using Hitec HS546MG servos, which is overkill. You can never have too much servo torque.

oldfrog

My Feedback: (1)

Really nice looking build going on here Tim, nice clean radio box too.

1QwkSport2.5r

Thanks, Roger. I think its going pretty well. This hull is really time consuming to build, and its hard to keep it light. On the first Kami I built, I used more 3/16" birch plywood which is a lot heavier. I dont recall the weight of the frame on the big boat, but this one has to be half or a third of that. The finished frame is 1 pound, so with the skin, electronics, and powerplant/fuel tank I'm hoping to be right around 3-3.5 pounds. I've got my fingers crossed.

More pics to come..

RS 38-40

My Feedback: (3)

Looking at the pictures I see you are going with a push pull rudder system . You are not worried about cable buckle on hard turns ? Maybe a pull pull would be better .

1QwkSport2.5r

Actually, I used a push/pull on the big Kami and it worked great. I used a pull/pull on a hydro I built and had problems with the rudder. The big kami is 7 pounds, this one will be about half that. I dont forsee any rudder problems.

dadkins

I was wondering about the rudder cable buckling too - looks like you have a good straight throw and if you didn't have problems before - why would you now.
Looking good...and light... maybe too light : ) you could always throw a handfull of D batteries in there to keep it from power looping, but its hard to take weight off.

1QwkSport2.5r

When we tried running my hydro that day, the problem that ended the day was the rudder cable buckled. On that boat, I used Dubro control cables which aren't brass plated and are more flexible than the Sullivan cables I usually use. The sullivan ones are stiffer cable, and are brass plated which makes them less prone to buckling. The hydro is the only boat that has had issues with cable buckling, that that is set up as a pull-pull setup. I set the radio box and cable arrangement up in such a way that the throws are as straight and level as possible.

On the weight issue; I am doing the hull as light as I possibly can so in the event of being "too light", I can add ballast.
I'll upload pics later tonight or tomorrow of the big Kami's servo/cable arrangement to give an idea how I set it up. My original rudder was junk so I re-did the rudder on it and had to lengthen the cable by a few inches. This kept the cable pretty rigid, and gave me the throw I needed to have a good turning radius.