Sig Kadet II. Removing dihedral, and motor options. - RC Groups
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Jan 01, 2013, 10:57 PM
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storkus's Avatar

Sig Kadet II. Removing dihedral, and motor options.

So, I've got this partially framed up sig kadet II. The wings are built with the stock dihedral, which is a lot. I'm thinking about getting rid of the dihedral, cuting off maybe one rib bay on the inside of each wing, and one on the outside of each wing, cutting off the wing tips, which would remove about 6 inches of span in total. I also want to put a really fast motor on it, make it a really hot plane. What do you guys think? I can't really think of anything else to do with this half-built kit that I started while I was learning to fly. Would these mods work out? Let me know what you think.

Also, do you have any suggestions in terms of power set up? I've never put together my own system before. I'm hoping to to have this plane come out at about 5 pounds.
Last edited by storkus; Jan 01, 2013 at 11:50 PM. Reason: Addition
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Jan 02, 2013, 12:55 AM
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scirocco's Avatar
Build it standard, sell it, and buy/build something fit for purpose.

Or, build it standard, enjoy it for what it is, improve your landings and rudder coordination. I can't bring myself to get rid of my stock Kadet LT-25 simply because it is such a nice flyer, and each time I get a nice axial slow roll is that bit more skill that goes into my pattern and 3D models. And I've powered it with near 800W and it sure climbed ballistic, but top speed remained modest.

You just can't make that into a hot ship - the wing section is too thick and thus has a lot of drag, it has has a lot of camber and thus has a strong pitching moment as airspeed increases, the longitudinal dihedral opposes going fast, and so on.

IMO butchering it without real prospect of achieving your goal is rather pointless.

If you want something genuinely hot, start with a Hobby King Rare Bear funfighter for around $80 plus a couple $10 3S-1000 packs, then when you're keeping up with that grab a couple of 4S-850s and hang on.
Jan 02, 2013, 12:59 AM
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storkus's Avatar
How much could I get for it if I were to build it? Not saying I wouldn't end up enjoying it, just want to make an informed decision. I don't really have the funds to have all kinds of planes lying around.
Jan 02, 2013, 01:19 AM
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storkus's Avatar
Here are some pictures of one of the wings. I also have another wing, and two fuselage sides all done. Haven't touched this for a few years, and I've been thinking it's time to finish it or give/sell it to someone who would.
Jan 02, 2013, 09:11 PM
I eat glue
Build it standard, keep it and enjoy the crap out of it!
Jan 04, 2013, 11:17 AM
Redacted per NSA "suggestion"
dedStik's Avatar
It's a kadet, huge amount of wing area, high wing, flat bottom wing. It's not meant to be fast or hot. You can remove the dihedral by adding a few shims of lite ply or balsa to the wing joint decreasing the dihedral angle. This would allow you to maintain the amount of wing area the bird is meant to have while giving you a significant amount of pizazz I think you are looking to put into the plane.

The Sig design of that bird is tried and true with more than 20 years of field service on that frame, why change a good thing?

Originally Posted by storkus
How much could I get for it if I were to build it? Not saying I wouldn't end up enjoying it, just want to make an informed decision. I don't really have the funds to have all kinds of planes lying around.
That's difficult to say. Are we talking fully equipped RX/battery ready or just the covered bird no electrics? Either way it's only worth what someone is willing to pay. The problem you may run into is that people would rather put $100 or $150 towards the model of their choice. They may not like the color scheme you chose for it. Personally I'd build it and hold onto it.

I converted a prebuild Great Planes Trainer .40 from glow to electric. This bird is not lightened. I powered it with this motor from HK, on a 4S 5000 mAh pack I get 500 watts WOT, and it only draws around 32 amps. AUW is 6.5 lbs.
Jan 05, 2013, 04:17 PM
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catspaw's Avatar
Kadet II was my first plane. Well after I was a proficent flyer on other birds, I used this for my knock around and fun fly plane. Replaced a lot of pieces in the process.

If you are set on reducing the diherdal, then do only a little, leave some in. One of our club trainers was a MkII, but had zero diherdal, and was a taildragger. NOT ideal for a new pilot, I'll tell you that! It was kind of squirrelly on takeoff, that being it's main problem.
Jan 05, 2013, 07:05 PM
I eat glue
I have a Seniorita that I cut the dihedral in half, put in ailerons and flaps, and made it a taildragger. Love flying that thing, flies faster than I thought it should be able to. I use an Eflite Power 25 and a 3s battery in it. 4s is gobs of power, can go vertical. Mine weighs about 4.5 pounds ready to fly.
Jan 07, 2013, 11:51 AM
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DustBen's Avatar
Finish building it close to stock.

A flat bottom airfoil plane doesn't invite "going fast" well.
The wing creates more lift at higher speeds, requiring more down trim, but once you cut throttle to cruise around, it dives, adding down thrust only goes so far, you can try mounting the wing with less angle of incidence but that too is a speed/lift compromise.

Finish the model, keep it, teach someone else to fly, and then someone else after that.

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