Nico Hobbies Mini Saab Draken Pusher Jet - Free Planes

[crxmanpat]

First, I'd like to say thank to Marcel ("vleisie" at RCGroups) for allowing me to use his Draken plans to create a mini version. Here is Marcel's original thread over there:

http://www.rcgroups.com/forums/showthread.php?t=1113351

So with his permission, I took the original plans and drew them up in CAD in a smaller size.

Here are my stats:

Wingspan - 17.1" (434mm)
Length - 26.65" (677mm)
Weight - 5-6oz (142-170g)
Motor - 1806N 19g 2500kv
Prop - GWS 4530 (4.5" x 3")
ESC - 10A
Servos - 2x 5gram micro servos
Battery - 3S 450mAh 25c or 2S 850mAh 25C
Radio - 3-channel with taileron mixing

Kits are available from my site, www.nicohobbies.com. There is also a link there to a full color build guide.

Here is the list of parts needed to complete the kit (these are the parts included in the basic kit from my site):

A. Main Wing/Body
B. Elevons (2)
C. Upper Rear Fuselage/Vertical Stabilizer
D. Lower Rear Fuselage
E. Forward Fuselage
F. Rear Chine Support
G. Forward Chine Supports (2)
H. Nose Cone (2)
I. Foam Motor Mount
J. Ply Motor Mount
K. Upper Chines (2)
L. Lower Chines (2)
M. Ply Control Horns (2)
N. EZ Control Rod Clevises (2)
O. Carbon Fiber Wing Spar
P. Carbon Fiber Vertical Stab Spar
Q. .039 Pushrod (2)


These plans are provided to RCGroups members for free for personal use only and may not be copied or altered for commercial use.

[crxmanpat]

The first thing I do on all my jets now is hinge the control surfaces. I find it much easier to do now before the other parts are glued to the wing. I hinge my control surfaces in the traditional manner, using small strips of scrap plastic as hinges.

First I prep the control surface by slotting the leading edge, then cutting 45° angles. I insert the hinges into the control surface, then slot the trailing edge of the wing. Finally, I glue the hinged control surfaces to the wing. You can also use packing tape, strapping tape or blenderm in place of standard hinges.

Next, it's time to glue in the wing and the vertical stab CF spars. Make sure you are working on a hard flat surface for this. I use 3mm x 1mm CF stick for this, but CF rod or tube will work too, so long as it's no more than 2mm thick so the epoxy can fill in all around it. First I tape over the slots with blue painters tape. Then I flip the parts over and put tape along the outer edges of the slots. This will help prevent epoxy overrun on the foam. Mix up your epoxy, completely fill the slots, add the CF spars, then use a scraper to remove the excess epoxy. Weight the parts down to ensure they remain flat.

Finally, after the epoxy has hardened, but BEFORE it cures, remove the painters tape.

[crxmanpat]

Next, you will join the forward and rear fuselage pieces (if you cut this from a single piece of foam, skip this step). These pieces are separated in my kits as they do not fit in the shipping box when joined together.

My kits also come with a foam brace in the prop slot on the vertical stab. Even if you cut this plane by hand, you should leave the brace in there until you have added the CF spar as the top of the prop canyon is a weak spot, and the foam will break easily if care is not take. At this point in the build, the brace can be removed.

[crxmanpat]

Now glue the wing to the fuselage. In order to ensure the parts remain square while the glue cures, slide in the foam and ply motor mounts, but DO NOT glue them in yet.

Next, glue on the lower rear fuse piece that keys up through the rear wing into the vertical stab.

Then glue in the rear chine support to the front edge of the wing, glue on the front nose cone pieces, and glue on the front chine supports. The inner edges of the front chine supports may need to be trimmed in order to ensure a good fit against the fuse.

[crxmanpat]

Because it will be difficult to make adjustments later once the plane is complete, you will want to go ahead and get all your electronics set up before proceeding further. You will want to center your servos and install the servo arms, get the servos hooked up properly to the RX for tailerons/delta wing, and ensure the ESC/motor connections are correct so that the motor spins counter-clockwise when viewed from the front of the plane.

Now you need to install the servos. Place them in the designated spots so that the servos are flush with the top of the wing. I also add a piece of packing tape to the top of the wing over the servos to help hold them in place, and to create a smooth surface. Then hot glue the servos in place. Finally, run the servo leads through the lower holes of the rear chine support.

[crxmanpat]

Now you need to assemble and install the motor mount. First, take the motor base and mark your holes for the mount screws, then tap the holes. Next, glue the ply mount to the foam backer. I use hot glue here as it grabs good, stays somewhat flexible, and won't crack due to the motor vibrations.

Once the ply is glued to the backer, you may need to clean out the screw holes. Now attach the motor base to the ply mount. Finally, glue the motor mount assembly to the plane. Again, use hot glue here, and also build up some hot glue where the foam backer meets the fuse/wing to ensure a solid joint.

[crxmanpat]

The next step is very important to prevent damage to your plane. You will need to add some pushrod guides to the outside edges of the prop canyon to prevent pushrod flex and prop strikes on the pushrods.

What I do is take the extra servo arms from my servo packs, and cut off all but one of the control arms from the hub. Then I ream out the top hole in the arm to allow free movement of the control rod. I cut a little square out of the wing where the guide will go, add a piece of painters tape on the top of the wing, then hot glue the guide in place.

Next, glue in the control horns. Make sure the pushrod holes are lined up over the hinge line. I hot glue in my horns as well.

Finally, install the pushrods.

[crxmanpat]

Now add the upper chines. Prior to gluing, you will want to do several dry fits and trin the chines as needed. Cut a slight angle in the edge of the chine where it meets the fuse to ensure a tight fit. Trim the rear of the chine so that it will fit snugly down to the wing. And trim an angle in the outer edge of the chine where it will mate with the lower chine.

Once satisfied with the fit, glue the chines in place.

Before moving on to the lower chines, go ahead and finish installation of the electronics. Run the ESC/motor wires through one of the lower holes of the rear chine support. Run a strip of velcro down the center spine for the battery. Add enough so that the battery can be moved to adjust the CG. The electronics should be placed so as to make the CG right at the wing break, or slightly forward from there.

[crxmanpat]

Prep the lower chines in the same manner as the upper chines, but do not trim them where they will mate with the outer edges of the upper chines.

Next, decide how many and where you want to create your access hatches. The pic shows a good location for them. It helps to have two hatches to make battery installation and removal much easier.

After the hatches are done, glue on the lower chines.

This completes the build! As mentioned in the post above, CG is right at the wing break. Slightly forward of the break is OK too. Only a minimum amount of control throw is required, 1/4" should do fine.

Be warned, this plane is fast! With the setup recommended in the first post, this plane will easily do 70mph or better.

[kenchiroalpha]

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[hillbille]

Here's one flying by at A-I-T-H in Vegas!

Looks pretty darn good too!!



Hillbille

[ministeve2003]

Hey Pat, I noticed in your build you cover the parts next to the spar with painters tape to keep the excess off... I normally use Rubbing alcohol, just use a paper towel and while it's still farily wet, it will come right off very cleanly... Rubbing alcohol works awsome with cleaning epoxy... so long as the epoxy isn't fully cured...

SK

[crxmanpat]

Originally Posted by hillbille

Here's one flying by at A-I-T-H in Vegas!

Looks pretty darn good too!!



Hillbille

Do you happen to remember if that one was about a 26" ws made from 6mm depron, or 17" ws made from 3mm?

[crxmanpat]

Originally Posted by ministeve2003

Hey Pay, I noticed in your build you cover the parts next to the spar with painters tape to keep the excess off... I normally use Rubbing alcohol, just use a paper towel and while it's still farily wet, it will come right off very cleanly... Rubbing alcohol works awsome with cleaning epoxy... so long as the epoxy isn't fully cured...

SK

Steve,

Yes, rubbing alcohol does work well for taking off epoxy runover. But I find it much easier to mask off the slot, then simply peel the tape away after the glue has hardened.

[hillbille]

Pat I'm going to guess it was 26" ws as it looked to right in scale with the other SU-27 (I think - I am lousy with id -ing planes!!) that was flying around at the same time. The shots taken were from about 75' away from the runway.

Hillbille

[crxmanpat]

Then it was probably from Marcel's original plans. I got his permission to take his plans and shrink them down to a mini-me. But if you put them side by side they'd look exactly the same, except for the size.

[jetmech2002]

Did you get any video from the flight?

[crxmanpat]

No, never got any. My display model is pretty beat up now, I need to build another clean one and get some video done.