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Old Feb 09, 2013, 09:21 AM
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Sweden, Stockholm
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Well, it flies! Probably well too, but I'll leave the exploration of the flight envelope to a day with better weather.

I'll start off with a bunch of pictures of it that I took when I was done. Videos in my next post.
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Old Feb 09, 2013, 09:35 AM
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Sweden, Stockholm
Joined Jul 2012
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Despite weather being bad (temperature at freezing, gusts of 5-6m/s wind and snow), I couldn't help myself from flying this little thing. I'll have to do it properly some other time because this doesn't really qualify as a great flight.

Snow was 3-5 cm thick and quite compact but still with a bit of a cushioning effect when crashing into it. Here's the video of the first time the plane got airborne:
Hacker Piper J3C RC Conversion First "Jump" (0 min 12 sec)


I did a few more flights after that, some circling the very narrow soccer court I was flying on trying to figure out trim. I had to add two clicks on the aileron, but that was it. What I had to do was decrease rates though, and add some expo. Having done that I did a short nervous flight with a landing that's about as controlled you could get it on this kind of surface, without ski's at least:
Hacker Piper J3C RC Conversion First Flight (0 min 31 sec)


I wasn't ever close to full throttle, so there's plenty of power in reserve, it seems to fly rather nicely. It doesn't turn very well on just ailerons and elevon it seems, it likes some rudder input to turn, but I hear that's typical for cubs?

All in all, I'm very happy with the end result, except the decals that I'll find some way of redoing. One of the lightning bolts on the side came off in the snow and I managed to bend the landing gear a tiny bit, but other than that (took 1 minute to fix the landing gear), the plane is intact to fly again on a day with better weather in a location where I don't have to be scared of trees and fences all the time.

I'm including a sneak preview picture of my next build project.
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Last edited by XeCutor; Feb 14, 2013 at 01:42 PM. Reason: spelling
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Old Feb 09, 2013, 10:40 AM
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United States, TX, Houston
Joined Nov 2003
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Quote:
Originally Posted by XeCutor View Post
It doesn't turn very well on just ailerons and elevon it seems, it likes some rudder input to turn, but I hear that's typical for cubs?
They for sure like coordinated turns. If you dial in some aileron -> rudder mixing it should clear that problem right up.

I think you will really enjoy building that Zero, Dumas kits seem really top notch. I built their Zero before the really cheap micro gear came out and just built it as a display model. It would have been great for the parkzone 1s electronics.

Here is the empty model, it weighs in at 24g, just to give you an idea of the airframe weight. The decals are peal and stick, so it saves you the hassle of waterslide.
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Old Feb 09, 2013, 01:01 PM
UMs & parkflyers... for now.
davidterrell80's Avatar
United States, VA, Herndon
Joined Apr 2012
3,022 Posts
Hooray! I am very pleased for you. You have a beautiful Cub! Does that make you the Mama Bear? I have been very interested in your build and the Dumas Zero makes me wonder... I have several of the UM boards in my parts box, purchased for some Stevens Aero kits, including two I've already purchased... a Heath LNB-4 and Fly Baby Biplane.

I'm going to reexamine the Dumas kits.

Again, I congratulate you on a beautiful build. May the Cub be a real pleasure for you, in the years ahead.

David
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Old Feb 09, 2013, 04:21 PM
Balsa&Tissue
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United States, OR, Beaverton
Joined Jan 2011
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Congratulations, the cub looks great and your flight was nicely done especially since the weather was so bad and the field so small with lots of trees! Very nice job of keeping the plane under control in such conditions.

Dave
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Old Feb 09, 2013, 04:31 PM
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Sweden, Stockholm
Joined Jul 2012
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Thanks for all the encouragement and interest in my build!

The Zero will be built using gear from a scrapped UMX Beast (v1) that I bought cheap. I'm not planning of using the motor though as I'm going to stick that into my flying Beast which has a wonky bearing in it's motor. The engine is also kind of heavy for the thrust it generates, the prop mount on it is also not ideal for the tiny Zero. I've just ordered a 6g NTM motor from Hobbyking that I'll use with the rest of the gear. Since it'll be a 2S powered little bird, it'll probably be quite heavy and very fast (compared to 1S brushed gear that seems to be recommended). With an airframe weight of less than 30g I should be getting more than 1:1 thrust to weight ratio using most appropriate propeller options!

I haven't decided if I'll cover with tissue or white So-Lite (which I have already at home). I've never covered with tissue so it'd be a good thing to learn. Since I'd have to buy some dope-type stuff in order to cover with tissue, it'd cost me a little extra. Anyway, the Zero will get it's own thread soon enough.
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Old Feb 09, 2013, 04:39 PM
Balsa&Tissue
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United States, OR, Beaverton
Joined Jan 2011
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Quote:
Originally Posted by XeCutor View Post
Thanks for all the encouragement and interest in my build!

The Zero will be built using gear from a scrapped UMX Beast (v1) that I bought cheap. I'm not planning of using the motor though as I'm going to stick that into my flying Beast which has a wonky bearing in it's motor. The engine is also kind of heavy for the thrust it generates, the prop mount on it is also not ideal for the tiny Zero. I've just ordered a 6g NTM motor from Hobbyking that I'll use with the rest of the gear. Since it'll be a 2S powered little bird, it'll probably be quite heavy and very fast (compared to 1S brushed gear that seems to be recommended). With an airframe weight of less than 30g I should be getting more than 1:1 thrust to weight ratio using most appropriate propeller options!

I haven't decided if I'll cover with tissue or white So-Lite (which I have already at home). I've never covered with tissue so it'd be a good thing to learn. Since I'd have to buy some dope-type stuff in order to cover with tissue, it'd cost me a little extra. Anyway, the Zero will get it's own thread soon enough.
You might want to try Coverlite. It is like tissue, light but tough like polyspan or polyester film. Takes paint really well especially scale model paints. Shrinks with a heat gun and iron and can be bonded to the frames with Balsarite or even carpenters glue and an iron. It is my go-to covering for small balsa conversions.

Here is a Dumas Dragon I covered in Coverlite:



Dave
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Old Feb 10, 2013, 04:41 PM
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Joined Jul 2012
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I did a few more flights today. The first one was relatively alright but affected by wind, landing was a controlled drop into deep snow.

The second one I got caught in wind strong enough to make the plane hower into the headwind at around half throttle, landing was an uncontrolled nosedive into the snow trying to avoid being blown into the close by trees.

The third flight was still a bit windy, this time I flew from a little ice-rink that was temporarily free of kids ice skating, that flight is posted in the video below. The two clicks of aileron I had added in yesterday were actually not needed, It flew neutral when I reset those clicks today. I still haven't really tested any full throttle flying, I'm sure it won't be very scale. There's plenty of get-out-of-trouble-power though which is nice, would be even better if the batteries responded instead of being frozen.. During this flight I realized I may have added too much expo so I'll remove some for the next flights, I may increase the throw on the rudder slightly too. Turning on the ground is slightly hopeless since there's virtually no weight on the tail and the tiny hard plastic tail wheel doesn't grip at all.

The wind picked up again in the end so I wanted to come down for landing no matter what, the landing got a bit bumpy and you can hear the spinning propeller smack the ice a bit when the landing gear did it's job and flexed. I'm using a GWS 6030 now, just because it's the only grey prop I have and it looks nice, a smaller one would look more scale and give more clearance. Maybe I'll cut it down and re-balance it. Anyway, here's the video:

Hacker J3C RC Conversion Flight (1 min 36 sec)
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Old Feb 11, 2013, 02:40 AM
Slip the surly bonds...
Sopwith Mike's Avatar
Christchurch,England
Joined Aug 2004
2,740 Posts
Very good, nice flight and landing.

Mike
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Old Feb 12, 2013, 01:51 PM
MPP
In Unusual Attitude Recovery
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Danbury CT (DXR)
Joined Oct 2005
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Congratulations! N-ICE model you have there. On a calm day i'm sure it will be a floater. Good luck with the Zero.

Best,

Mark
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Old Feb 12, 2013, 08:50 PM
Heads up...
RMCCOR7737's Avatar
United States, VA, Stafford
Joined Jun 2009
744 Posts
Congrats. Looks great.
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Old Feb 13, 2013, 04:12 PM
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Joined Jul 2012
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If anyone is interested, this is where I've started a build thread on my Zero. I thought it would fit into any of scale electrics, balsa builders and indoors & micros but I went with micros.
http://www.rcgroups.com/forums/showthread.php?t=1831201
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Old Mar 01, 2013, 11:49 AM
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Sweden, Stockholm
Joined Jul 2012
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Since the voting has started, I thought I'd do a last-minute campaign to increase my chances.

Jokes aside, here's a video of some flying last weekend when it was dead calm. I used up at least 6 batteries and did a few spotless three-point landings on the path through the park. This flight did not end like that. To be honest, I'm not exactly sure what happened, some kind of tip-stall maybe, maybe a slight gust of wind? No damage was done and I flew again directly afterwards. The battery in my phone went flat so I did not get any other flight filmed.

The video shows the slow-flight characteristics of the plane reasonably well. The plane is very sensitive to wind, that's for sure. It flies at what I recon is a reasonably scale speed. It'll do loops without much protest if you apply enough power. It can roll, but it puts up a fight when you try it. I did it once (not on video) at height and it took forever for it to tip over on it's back. I'm guessing it's because of the high wing and the low center of gravity, because the ailerons are pretty effective for normal level flight corrections and turns.

If you build one and manage to shave 10g off, you'll have a real floater and something that could probably glide a bit as well. Mine is slightly nose heavy (but not enough that I feel I need to add tail weight to fix it) and has a pretty steep glide path when the engine is shut off.

Anyway, here's the video, please excuse the glove or whatever it is covering the bottom right corner:
Hacker Piper J-3C flight with an embarrassing but damage-free end to it (3 min 31 sec)
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Old Oct 14, 2014, 05:32 AM
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Sweden, Stockholm
Joined Jul 2012
293 Posts
I'll revive my ancient thread hoping that somebody who has the same kit lying un-built reads this and is willing to help. My Cub is fine and gets to fly whenever the weather is calm, it really doesn't like wind that much. Unfortunately the water slide decals haven't really survived that well and they're gradually falling off. I have a roll of black so-lite covering, but it's hard to get the cut outs right without a template. If anybody with the kit could do a scan of the decal sheets, especially the lightning bolts across the fuselage, that would be very much appreciated.
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Old Oct 14, 2014, 09:48 AM
Balsa&Tissue
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United States, OR, Beaverton
Joined Jan 2011
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next time clear coat the decals with some water based poly u or similar.

Dave
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