"1/2 A" & "1/8 A" airplanes These are the small ones...more popular now than ever.

DNU gets a speed boost...hopefully

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Old 11-13-2013, 06:12 PM
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xanaphyst
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Default DNU gets a speed boost...hopefully

After putting quite a few runs on my DNU I decided to play with the airframe a little and try out a norvel 061. I framed up a new one with a modified thinner airfoil and cut down the wingspan a bit.
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Old 11-13-2013, 06:16 PM
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Building my own fuel tank with tin. I watched a youtube video and gave it a go. It turns out that it isn't very hard. The triangle shape really lets you get all the usable fuel..or so I'm guessing.
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Old 11-13-2013, 06:19 PM
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Installed the tank and made up the firewall. I thread a carbon fiber rod on the crankshaft of a TeeDee and used it to set firewall alignment. An easy method I believe I picked up here in a combatpigg thread.
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Old 11-13-2013, 06:24 PM
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Will you be putting some webbing between the spars?
What power plant did you have on your DNU before you're quest for the sound barrier?

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Old 11-13-2013, 06:45 PM
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no webbing, The short wing feels fairly stiff. Time will tell if I should have put it or not. I wasn't going to post this build at first but figured others would have some insight on things I could have done better. The wings are covered now so I won't be able to add them. Thanks
for the tip. Now that I think of it my other DNU didn't get the webbing either. Gonna have to pay attention to the plans next go round.


The original DNU runs a backplate cox with teedee cylinder. I have really good luck with that engine, always runs well. This one will get 061 norvel power.

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Old 11-13-2013, 07:02 PM
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The original plan and kit has a 3/32 vertical spar to make an I beam. Very resistant to "G". And the power plan was?
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Old 11-13-2013, 08:02 PM
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Nice looking project..!
The AMA 1/2A Pylon rules call out for a minimum 1 inch thick airfoil [just to give you some comparison to what you've got there].
Those planes are pretty fast on a 300 foot oval..less than 10 seconds per lap.
The Utah 1/2A racers use [used?] much thinner wings with their own set of rules and those planes really move out.
I hear you aren't having much fun with diesel..? I don't like the way it creeps under the covering, it creeps into every tiny crevice trying to turn planes back into compost. Glow is bad enough, but diesel is in a class of funkyness all to itself..!
I still have a couple PAW .15 powered combat planes and I keep all that junk stored with my farm tractor.
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Old 11-14-2013, 01:20 PM
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Put the plastic to her and did up the glow fan. Rigging and electron bits still to go. Looking 12 oz RTF
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Old 11-14-2013, 04:38 PM
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Went back to the shop after dragging out the christmas tree...yuck!!! Completed the rigging on the wing and installed battery and jack. Only thing left is elevator servo, elevator rigging, install receiver and charge the batteries. Previous weight estimate a little high. Looks like she will be 10.5 to 11oz. RTF. Hope the weather is good this weekend.
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Old 11-15-2013, 01:53 PM
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http://www.youtube.com/watch?v=m3z8-...ature=youtu.be

Didn't go as well as I hoped. I made a bad prop choice on an old cutback master airscrew and ran it too rich. It was an old prop from my delta wing days and now I remember it sucked back then as well. It's ok though because my starter unscrewed the prop and bolt and threw them both way off in the tall grass somewhere. Swapped it out for a 5x3 cox grey I had in my box and it seemed better on the ground but still not right. Nose dive on launch and found the wing bolt had stripped out. Everything still fine just need to fix the wing mounting and get the engine right. All up weight was 9.8 oz.

http://www.youtube.com/watch?v=nDLqz...ature=youtu.be

Took out my regular DNU after putting away the cut wing. A great plane and I always have fun with it. Decent vert. at 10.5 oz.

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Old 11-18-2013, 08:09 AM
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I can't recall ever being happy with the results of a trimmed MA prop on 1/2A's, tried it a few times for various reasons. Maybe because they are not efficient enough to start with..?
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Old 11-18-2013, 08:37 AM
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Finally ! Some applied effort was what it needed to get her right. The new AMD wasn't giving me the results I was happy with. I was guessing the problem was fuel draw all along as the tank is set a little far back in the fuse. Suspect #2 was the RC carb pinned open perhaps wasn't giving me all the fuel draw I needed. The needle was never consistent. I set about to increase the tank pressure and provide a better inlet venturi. I didn't want to run a muffler at start but decided to install it so I could use the pressure port. The carb on the older models is glued in so a little applied heat was all she needed to come on out. I looked into using the NV combat model setup but that didn't look ideal to me and I didn't find a needle valve that I thought was an easy fit. Digging in my MP Jet parts I found that the carb mounting is very close to being the same as the norvel.. A little trimming on the MP Jet venturi body had me in business right away with a jury rigging tie wrap holding it down. The spray bar on these have 2 ports 180 out from each other an figured this might give me the extra suction I needed. The bottom line is that the results were perfect with a wider needle range and consistent engine running regardless of airplane being pointed up or down. Now it sounds like it should. I'm sure the neighbors enjoyed the 7:00 am engine run as much as I did.
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Old 11-18-2013, 04:19 PM
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Dang....still no joy. The first flight today ended quickly with a nose plant. The second flight is the video link. I believe the nose plant made the venturi come a little loose and I did not notice this until later at home. I made a third flight which was little better. The engine came on song well for 2 passes with a nice sound from the engine unloading. I still have some airframe trim issues to get worked out as the plane is all over the place. I did not get the last flight on film as my camera is taped to the side of a pair of dark sun glasses and it was making it very hard to see the plane as it was late in the day. All in all it's getting better, almost there.

http://youtu.be/26BVZ_3wjcs
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Old 11-19-2013, 01:41 PM
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http://www.youtube.com/watch?v=pnruU...ature=youtu.be

round three...still a little better yet. Engine still fussy but improving all the time. Turns out the cox plug and some different fuel helped. Air frame is pretty slow and not so stable.
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