102511

this is my first scrach build. i am useing the dnu plans by ptulmer. it will use a sure start and have rudder/elivator controll. i will change the wing from semi semetrical (spelling) to a flat bottom trainer wing. i got the wood from balsa usa and i think i ordered to mutch. this build will probably go very slow. i have built kits and arf's but they never needed to be covered (all sheeting and paint). this is also my first 1/2 a plane. i know this plan is popular so any tips are welcome. i have a hitec radio and 2 9 gram cirus servos so all in need to order is a reciver. any suggestions?

Dukester

My Feedback: (31)

First off, it's an easy build relatively speaking. However, a few points to add to your planned changes. If you go rudder/elevator, you'll need to add dihedral to the wing. This is not hard to do, but does require modifying the plan and is slightly more difficult as you have to fit the wing panels together. I would suggest just keeping it ailerons/elevator as planned. No bad habits and easy to fly. You can make the wing flat bottomed if you like, but it has plenty of lift as it is.

For a receiver, for cheap I have been pretty happy with the GWS 6 channel receivers. For more money but a good light receiver, I like the Hitec Electron 6. If you look around you should be able to get one for $40 used.

happy building,
Duke

combatpigg

My Feedback: (3)

102511 [another inmate?] ,

The most common mistake by first time coverers, is tacking the film down with too much heat. You don't want to see any shrinkage yet. You should be able to lightly tack the film down on a fairly low heat, and work the material across the largest expances, and just tack the perimeter of the wings' frame. Then begin the process of going around with more contact from the iron until you have sealed the edges. The fun part is the last step which is turning up the heat for shrinking, and of course ironing out any twists the might have found their way in to the wings' framework.

ptulmer

My Feedback: (5)

There's no such thing as "having too much wood"! (that was for you CP)

102511,
If your reason for going to the flat bottom wing is to make it fly slower and more trainer-like, you'd be better off widening the wingspan. Balsa USA is a great source for light wood. Watch the grains and weigh the pieces. That's the difference between flying a pig and a great DNU! Most of all, have fun!

dieFluggeister

I second Dukester's thoughts. A conversion to R/E with a flat bottom airfoil will be difficult and opens a whole can of aerodynamic worms. (Actually worms are fairly aerodynamic but need to be stiffened with CA to prevent flutter.)

The DNU is really a forgiving and gentle ship and is hard to stall or spin. It already has lots of lift and glides with the power off very well and slowly. But it does take some skill due to it's 0 dihedral wing and will not return to level if you roll it on it's side. It is also appears fast just due to its size, and orientation can be an issue if you let it get too far out.

If you are trying to make the DNU more docile, I suggest using a 6x2 prop, and maybe a lower nitro fuel (blended for correct castor content). There's also no shame in taking it to a vetran at your field and asking their help in trimming out the plane on your first flight and having them hand you the controls.

ProBroJoe

Don't get me wrong, I love my DNU!, but I think if I were to do it again I'd pay closer attention to the weight and make it a full 4 channel plane. There have been a coupla times where I wished I had a throttle and rudder too. Those changes w/ a Norvel .061-074 R/C on the nose would make it a blast to fly, but then again, you'd be getting away from the original intent of the design.

If you feel the DNU! needs tamed down a little, why not consider a LS150, LST, or Whizzard instead? You should still be able to use most of the wood that you have already, and there are a few other plans that take the ACE 1/2A foam wing - straight and tapered versions. (I'm pretty sure that ptulmer has created and offered CAD files of a "built-up" version of those said wings.)

If you look back a few pages (or 6 or 7) you'll see where I posted a video of my DNU! in action, although I'm not an "expert" pilot by a long shot, the video should give you an idea of what you're in for if you build it as planned.

Hope some of this helps,

-Joe

102511

progress. rudder, elivater, and wing things. my mom is going to town today so she is picking up a coping saw so i can cut the ply formers. i knew about the dihedral but how mutch? i will build a center wing section and 2 outer panels. i will brace the joint with ply.

combatpigg- that is my school id # so you could say inmate

how much longer shuld i make the wing? can i use the ailerons and dihedral to make it more stable? as for saveing weight can i remove the wood from the center of the elivater (leaving some strips for strength kind of like ribs on a duild up elivater) and then cover it? i think i wil go with the prop/fule change. i have a sure start with throttle ring so i might put that in.

ptulmer

My Feedback: (5)

The wing on the DNU! is a cut down ACE wing. If you go with something in the original size range and include some dihedral, you know what to expect. About 36" would do it. I'd stay away from the R/E controls. Since that would be out of the realm of what's been done, you would be breaking new ground. Ailerons aren't more difficult to learn than the rudder. dF hit the nail on the "speed head". Prop selection is more important than anything else when determining speed and launch-ability. And even though the CA will prevent "earthworm flutter", I don't recommend it. They taste funny after that.

102511

could i get away with rudder/elivater/ailerons. would the extra servo add to mutch weight? what about adding throttle? where can i save weight?

ptulmer

My Feedback: (5)

You can save weight by making it two channel. Use submicro's like the hs-55's and a small 250-270mah battery. Don't worry, you'll be busy enough with two channels. Three wouldn't be bad, but would add an ounce or so to the final weight. Four is just too much. This thing is about making something simple and extremely effective. Don't complicate it or you won't enjoy it as much.

102511

thanks. i will start cutting ribs today. i think i will cut one out of ply to use as an exacto template. after they are cut i will use spar stock to conect them so i can sand them to final shape (this is my first scrach build so i will probably be telling you things that make you think no duh stupid). i may cut the fuse sides today but i want to cut them a the same time (one sheet on top of the other). shuld i use loops of masking tape to hold the 2 sheets together or clamp them somehow?

ptulmer

My Feedback: (5)

Magic tape or that blue stuff should be ok. No need to over-do it. Cut your spar slots into the template. No final sanding should be necessary![sm=thumbup.gif]

102511

all ribs have ben cut. the fuse halfs will follow.

cwrr5

My Feedback: (32)

Cool! Lots of fun, huh?

102511

yes but i have been building downstairs (near the tv) so the famaly has been swarming. you know, with all those stupid questions. what are you building, will it fly, how fast will it go, where are you getting all the money for this, have you done your summer reading? also my mom likes to throw away things that are left unatended (3 servos got trashed because she did not know what they were). i have postponed any building untill tomarow. there are to many anoying people around.

Dukester

My Feedback: (31)

Despite trying pretty hard, I couldn't get my DNU to spin or do anythign unexpected. If I held full elevator and ailerons, I could get it too corkscrew some, but as soon as I released the sticks, it just went straight in whatever direction it was facing. I'm kind of at the limits for elevator rnage of motion, but I could go up on the ailerons a little bit. Once trimmed after the first flight, it's very stable from launch to landing.

Duke

combatpigg

My Feedback: (3)

102511! [X(]LOOK AT YOU GO!! You sure are good with a knife! You must have bribed the guard in your cell block for more time before " lights out" ! What did it take, a couple of smokes? 102511, if you keep up the good work and you have done your time and repaid your debt to society, then you can come to work for me at my FCLARFSS [Forced Child Labor, ALMOST READY to FLY Sweat Shop] in, MEOWSTEW, CHINA.

102511

well i lied. i cut out the fuse formers. the copeing saw did not work well so i did it with an exacto blade (i am not sure what #, it was not a #11) it took 2 hours. i need a band saw.

a pic of all progress so far. everything is cut except the fuse sides.

ptulmer

My Feedback: (5)

If you're serious about a power tool, go for a variable speed scroll saw. WAY more useful. I even do some craft work for the lil lady every once in awhile. Band saws are useful, but they're called a resaw sometimes because they are great for ripping. That's really all they're good for if you have a scroll saw in your shop! A coping saw will work if you have some hardwood scrap to use for a jig.
Nice work so far! You'll be in the air in no time! Looks like you decided to go with a straight "ACE" wing?

102511

yes i did go with the plans wing shape. the problem is i have no place to put large tools. a while back i could have goten a milling mashine for $50 from a famaly friend. i could not put it in my room, the garage is not heated or water tight, and the only outlet it could run off was in the kitchen being used by the oven. think of the engines i could be makeing right now. a scroll saw is not that big but my mom would not let it in the house and it wiuld get wet in the garage.

moveing on. shuld i build the wing or fuse first? the wing will have to be built in 2 pieces because my build board is not long enough to build it in 1 piece. tomarow i plan on some serious building. i have the house to my self so that means blasting some tunes and balsa dust[>:].

dieFluggeister

Oh man, you will be so pleased with the result! Thanks for not making me talk you out of a different wing planform.

102511

the sides are cut and sanded.

102511

now thw fun part.

102511

wing half and center section. my build board is to small to build the whole wing in 1 go. the build board is the magna board that i got off some web site. it uses magnets so there are no pin holes in your spars.

flying poodle

Your 80% their when you have the parts cut. Glue them up and you'll only have 80% to go with covering and radio installation. The parts look real good.

BTW
A nice building board for our size planes is an acoustic ceiling tile. You can usually pick up a slightly damaged one at a building supply store for next to nothing, and it will last for years. When you are done working for the night, just remove the plane parts and drop the building board behind the couch. I did this in my dorm room in college.