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I understand that the biggest gains are with the wing but what I was commenting about the tail was that if you're going to do that much work to the wings, why not go all the way? Would you climb Mt. Everest and 2 ft short of the summit say "that's enough. I'm going home now." Now just patiently waiting for this to get back in stock. |
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I just had the maiden flight of my new bone stock Kunai rxr last night and I wanted to say thanks for this thread, It's great to see so much information cataloged.
I'm new to "warmliners" and have only had a few flights on my Rapide and the wing loading and finish of that styrofoam plane just was not what I was looking for. I wanted some soaring and a much lighter and less flexy and more durable build. Going fast is great if I can slow it down to land or float around a while. I have been looking at and really want the Soaring USA Destiny electric but I feel like the Kunai was a good and very affordable intermediate step. I am shocked at the completely square trailing edges. is that just for cheap manufacturing or hangar rash durability, or is there some aerodynamic reason to it? One of my ailerons is a bit warped. Stripping and sanding it would be plenty to straighten it, but it is probably easier to just make a new pair. I live in a pretty flat area and what's hilly is river bluff and densly wooded. There are a few dry dam / reservoirs near me that I would like to try to slope soar on but there are not easy landing areas, I think I need to land very slow and possibly on steep the grass face of the dam. There is a road and fence across the top so not good there. That said, What flaperon / spoileron throws do you like for landing slow? Do you have them on a variable knob or just on/off? Do you have a thermaling setting? I put the FrSky G-RX8 vario radio in it and I would really like to try to thermal it if that is even possible with this stock plane at 20.75oz AUW. Lastly, Two other planes questions: I think I want an Elf DLG to try to thermal/slope soar over those dams. And I am interested in the Destiny. What's the typical wing loading of the Destiny electric anyway? is the Destiny comparable but much nicer quality or is it a much faster plane altogether? I have an airplane problem. I've bought or scratch built 5 planes in 2 months and I have the destiny and elf on my wishlist. I am seriously thinking about a paramotor (full size!) Maybe it's a "wind problem"? I just learned to sail racing dingys this summer and I'm a little obsessed with the mysteries of the wind. |
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Last edited by dsergison; Oct 18, 2018 at 10:05 AM.
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Anyone know a good spinner for a .162 inch motor shaft. Supposedly, it's a little wider than 4mm.. There could be a slight error. I am also using a 1000 mah 4s. I noticed that the new motor I got is heavier. I may have to figure a way to move the battery further aft. Anyways, I am thinking perhaps this would work. With the new motor shaft. As its a different size than the other stuff I had. For the stock shaft.
http://www.espritmodel.com/aeronaut-...ropellers.aspx 33/4mm http://www.espritmodel.com/aeronaut-...ropellers.aspx And this yoke. 36/4mm |
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I've used a few of the 30/4/8 that comes with the yoke. Or the 30/4/8 BB aluminum turbo spinner.
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Hi All, I'm a bit late to the party as I have only just purchased a Kunai! In reading through the 25 pages here I have found out all sorts of this to improve the performance of the Kunai.
I have reinforced the wing, removed the rudder servo, put a small spacer under the trailing edge of the wing, changed the standard prop to a 8x7 carbon one. on average I'm getting 25 min of flight time on a 1300mA flight pack. My only real issue is the amount of climb the model has when I light up the motor. I assume the thrust angle need looking at. Can anyone give me an idea as to what spacers I need to put under the lower motor mount to give a neutral power on flight path? Also I'm a little disappointed with the off power "dive" speed. It like the model has a parachute. I don't seem to get the woosh sound that other have had. Possibly down to the lower drive speed? Apart from this I am really enjoying my new (better late than never) Kunai. |
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Last edited by The Hobbymaster; Oct 27, 2018 at 12:04 PM.
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With the firewall being wood you might want to use an angled shim instead of a washers. Make it out of wood or soft brass and sand/file it as needed. Try 1/16in thickness at the bottom so the motor noses over.
She is a very draggy bird and why you hear so much swoosh as she goes by. I believe it's just the nature of the design and you have to clean up the LE and extend the TE to smooth out the airfoil before you can see results. There are other planes worth sinking money into before you get too heavy into mods unless she's a labor of love and fun to have around like I've enjoyed. She still slow way down on me even with all my mods......you just learn to enjoy her flight envelope. It's a pretty nice spread in comparison to most other gliders I've had that I can just grab and toss in the back of the car. I get my kicks from the fast climbs and then just gliding back. 25 minutes is fantastic. If you want to fly around faster you just put it on 50% throttle and go. Nothing has been as much bang for the buck with a little 3s/4s battery. |
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Last edited by DeadstickDuck; Oct 27, 2018 at 06:08 PM.
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Hi
I have been reading this site over and over again. There for I have purchased a Kunai. Wow it was a hard job to find it, because Great Planes are bankruptcy. I was lucky to find a new Kunai in Germany, so now I have built it, and are waiting for the spring to come here in Denmark. I will go whit the stock motor at first, so I can lean to steer it well. I have done 2 modifications. New covering and the scrim under the TE. I hope it will help me to control it better, at the maiden flight. Best regards, Torben Pedersen Denmark |
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New beginnings
It is always exciting to maiden a new plane. Good luck Torben. Once you know how she flies stock you will see what each modification does and rewards you
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https://www.rcgroups.com/forums/show...kDuck-Nike-EVO |
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My advice is make the shim and take it with you but do some hand throws without the shim in there. See how it glides with just a hand toss and no motor. If it's horrible then put the shim in. If when you get to powered flight it doesn't fly like you want then start adjusting. Not all kunai's come out of the factory needing that shim. If you've never flown the kunai you'll love it, it's my favourite sport plane. Mine is totally stock as it came out of the box and I love the huge speed range it has from floating around to quite fast flight. Some guys have had great fun turning their kunai's into rocket ships but I'm happy with stock motor, prop and 3S lipo. Cheers |
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Very true. Everyone builds their Kunai so depending on how accurately someone gets the horizontal stabilizer flat to the tail boom the "decalage" can vary, which can alter how well she glides without power. The "shim" is what we came up with to help angle the wing up.
Also depending on the which year of production the thrust angle was updated to help keep her nose down during full power. So, some mods are not needed. |
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Hi
leakywellie and DeadstickDuck. Thanks a lot for the input. I have only put a shim of 1mm under the trailing edge. My CG is as describe in the manual set to 70mm for the first start. I will try to hand lunch it, whit these settings, out the motor running. If this going well I’ll will start the motor, and test the flying. If this go well. I can perhaps, move the CG back a little more, for more speed. Best regards, Torben Pedersen Denmark |
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Last edited by solvin; Feb 22, 2019 at 10:21 AM.
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Hi
If all go well whit my Kunai, I consider to by the Reichard Sprinter Hotliner ARF. I know it’s a old plane, released in 2009 but it is cheap, only 245 USD or 1600 Danish crone. Best regards, Torben Pedersen |
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