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Nov 21, 2005, 03:22 PM
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Walkera SU27 Build thread


Hey All

Welcome to the Walkera SU27 Build thread, Where Balsa Products has just started to ship them, and there are many more questions than answers, I figured Iíd start this thread.

This plane can be bought here http://www.balsapr.com/common/keywor...ductId=V536602

Walkeraís website is here http://www.walkera.com/home_e/index.jsp (loads SLOW), I believe this is the plane Glider # GM015 http://www.walkera.com/home_e/glidere.jsp ( again loaded SLOW) and here is the OEMís video http://www.walkera.com/home_c/mwv_c/plane15e.rm

I ordered mine the 20th and Iím hoping to get by Friday so I can start the build, I ordered it stock because I already have 2 Walkera 3300 KV brushless motors on hand. In looking at the other ducted fan planes they have, I saw this motor was offered as an upgrade to some of their plane.

So besides the usual pictures, my first step will be to the test the fans with the Walkera brushless motors, with the goal to see if they can actually be used.

This Walkera motor is powerful and can handle 15-18 amps (there are many here currently running tests on this motor), and I was able to get them for $23 each shipped.

Here is the thread on that motor https://www.rcgroups.com/forums/show...light=walkera+

I invite all those who just ordered to participate, the more the merrier and this will also allow for a 1 stop location to get a majority of the info needed for this plane.

Awaiting itís arrival Hee Hee Hee


Brent
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Nov 21, 2005, 05:00 PM
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subscribed! I'll jump in also when mine gets here..now excuse me, I gotta run out and pace by the mailbox...hehe.

Keith
Nov 21, 2005, 09:03 PM
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downloaded and converted


Hey All

I downloaded and converted ( from RM to WMV) the OEM's video.

http://media.putfile.com/plane15e I'm guessing this was the brushed version.

Brent
Last edited by afineman; Nov 29, 2005 at 12:09 AM.
Nov 23, 2005, 07:05 PM
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Received and first impression


Evening ALL

Let me first start by saying I am new to ducted fan ( I don't know if the GWS A-10 (stock) gives me any points), and starting to enjoy Speed as well as the Jet look.

What I will be posting will be my opinion and what I think (at that time) was the best way to to accomplish this building, rigging, and outfitting, this will all culminate in the maiden (and video of course).

My RC addiction comes with guidelines (self imposed), I call it CLF, this stands for Cheap, Light, and Fun. One of my goals in this hobby is to able to laugh as HARD as the spectators do when you crash, as we all will do. Now that the disclaimer is done ( Hee Hee Hee) lets get started.

First impression is "Big", I never expected it to be this big ( the photo has the Slow Stick in it for comparison)

Second WOW was the size of the Ducted fans ( dual 80 mm).

I already set 1 fan up with the Walkera 3,200 KV brushless motor. I sparked it up and got 22 amps on my amp camp ( a little more than I want, but that was static and I can always set the limit on the tx). The fit was perfect and had good pull ( for the ducted fan people, does static vs in flight rules for props hold true for fans as well)

My goal for this evening is to hack together a way to get an accurate measurement of thrust and be able to report on that. if these motors can be used, we can get them for $23-$25 each ( now that keeps it cheap ).

I also intend to do a water break-in of the brushed motors, I will use the 2nd fan unit so I can do a side by side comparison ( for those who want to fly stock).

Later All


Brent
Nov 23, 2005, 09:04 PM
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Next Update


All

I have not (yet) come up with a good way to measure the thrust on these DF with the Walkera Bl motor, so rather than waist time I started on the Fuse.

The entire Fuse has casting dimples on it, and they stick out too far (my opinion), as well as the ailerons movements is too stiff ( this may be part of the reason why BP recommends a separate BEC).

I cut away the aileron (first photo) and sanded the dimples off, then found it (being cut away) to be flimsy, not wanting to rely on "Packing Tape" for the hing ( I have had failures in the past using this method) or the strength, I decided on a different route.

I gently laid packing tape on both sides of the aileron (I didn't want the packing tape to warp the aileron) and trim ends with a razor blade ( NOTE here, if the razor starts to drag, replace it or it will rip things up ).

The third photo is of the finished aileron (I don't know if you will see the difference).

I will be spending a lot of time removing the dimples ( maybe this mindless work will have me come up with a good way to measure the thrust ).

I'll post when the wings/ailerons are done and I'll show my hing points (prior to affixing the ailerons to the wing)
Last edited by afineman; Nov 24, 2005 at 09:46 AM. Reason: to include the photos
Nov 24, 2005, 04:39 PM
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CF rods and the wing


Hey All


Happy Thanksgiving

Just a quick post, the wings are sanded ( I hate sanding, but those darn dimples stuck out too far ), I also added an extra CF rod to the wing, only 1 CF rod comes with the kit and it is for the trailing edge.

On the leading edge of the wing there is a shallow grove ( as thought it was for another CF rod), this grove had to be enlarged to accept a CF rod, but I think it will be a worth wild mod.

Also the CF rod extends beyond the wing so it can be glued into the fuse.

More to follow

Brent
Nov 24, 2005, 07:09 PM
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A better way to remove the casting marks


Hey Again

As I said I hate sanding and the thought of having to sand the entire plane made me , SO I tried something and it worked.


I took a very low wattage soldering iron, I took a 3/4 inch dia. 2 inch long Cooper dowel, I attached it to the soldering iron.

I used the flat tip of the hot rod to melt the casting bumps level with the surface. On the parts of the plane that are contoured, I am using the side of the rod like a roller.

Now I don't have to sand but I will still have to paint ( I have 1 wing 2 rudders, and 2 ailerons sanded ).

This method could be used on any foam plane and does make the surface smooth and (if care is taken) won't disturb the paint.

Here is a before and after picture, you can still see the outline of the bumps but they are flat.

Hope it helps


Brent
Nov 24, 2005, 10:10 PM
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The Elevator


Hey All


Last post of the evening ( beer kicking in ), let me start by saying, using heat to remove the casting marks will NOT save you any time, and you will STILL have to paint it in the end, regardless of how careful you are.

Having said that, it is still "My" preferred method.

The elevator, Balsa Products recommends cutting in the elevator. I used DuBro hinges ( as can be seen in the photo ), and I also cut in a grove for a CF rod for the elevator.

Later All

Brent
Nov 24, 2005, 10:15 PM
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great working man...thank for the photos...the su look great,,,i can't believering it that big...wow
Nov 25, 2005, 12:52 AM
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Cools, I am watching and looking forward to the maiden. This is really what I have been looking for, a shame GWS is kicking back on items like this.
Nov 25, 2005, 04:06 PM
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hey hey, mine came today!!! man they weren't kiddin', this sucker is BIG.. i just got all the parts out for inspection and all is A-ok, no damages at all. All the parts seem to fit pretty good, so I think it will be an easy build. I wont be doing any sanding, the pockmarks don't bother me. I will be adding afineman's idea of the extra carbon rods, though, couldn't hurt. So far I'm real impressed with this kit. Hopefully I can get started on it next week, I still have to finish up my WM Cessna first. The jet even came with a cutesy chinese can of brush-on adhesive, what a hoot.

Keith
Nov 25, 2005, 05:20 PM
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Stock or not?


ksavage68

Are you going to build it Stock ( I know no sanding ), I mean the brushed motors?

All

I've spent the day removing the rest of the bumps ( Hee Hee Hee) and building the other side. Currently the glue is drying on the ducts (OOHH let me take a picture, it may help others, also I used the GWS glue, you know the contact cement ). I will be flying with my brother/camera man tomorrow, I will try to finish it up tonight, so I can maiden it tomorrow.

If that doesn't work maybe Sunday ( both days will be 2 mph winds).

On closer inspection of the Walkera site, the brushless motor they sell that is a drop in replacement for the brushed motors, should be powered by a 9.6V NiMh pack, I believe the reason they do not offer this as an option on their twin DF is because of the C rating on their batteries.

I will be over powering these motors and at WOT I will be using about 450 watts.

I have a question, with prop-ed planes 50 Watts per pound for level flight, 75 for mild acrobatics and 100 for the crazy stuff, does the same rule of thumb hold true for ducted fan ( I'm hoping it does ).

Anyways off to try to finish the build


Brent
Nov 25, 2005, 07:18 PM
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DARN! why cant I just build it stock


Hey All

Rather than RUSH it for a maiden, I decided to stick with the first game plan.

SSOO unless Santa's little helpers come down to help, the maiden will be next weekend.

Anyways, here is the color scheme I have chosen (the colors are more for these old eyes), orientation should not be a problem


More to follow

Brent
Nov 25, 2005, 08:56 PM
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well since I don;t have two matching brushless motors right now, I thought i would just build it stock to get the hang of how it flies. I will make the fan units removable, maybe by doing hatches on the bottom engine nacelles. I still hafta figure out if i just want to run on elevons, or run aileron-elevators, I'm leaning toward the latter. I'll probably use dual ESC's and dual 3s-1800 lipo packs, unless somebody schools me in a better way to do it. I do have some NiMH packs but I dont know if you can put that kind of weight in this plane, anybody know? I'm looking for any suggestions on what brushed motor equipment to use, thanks guys.

Keith
Nov 25, 2005, 09:39 PM
Hey Now
I'm really looking forward to seeing how these fly! Looks like a neat foamie.
Keep us posted as I may have to order one if the build and flight goes well.

How easy is it to get to the fans and how easy is it to change the motors when the airplane is finished.

Scott


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