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Old Feb 05, 2009, 09:17 PM
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Build Log
FlyRC's Bob Aberle's Boeing L-15 Scout Park Flyer

This is the L-15 that was shown in the March 2009 FlyRC magazine. I've checked and I haven't seen anyone talk about this little plane, nor have I seen any build threads. So...I thought I'd start one

The link to the plans and some of Bob's build pix is here --

http://www.flyrc.com/articles/boeingL-15.shtml

My pix are below. I've done a couple upgrades to his design.

1. I ran a carbon fiber rod along the leading edge of the wings to help strengthen the design.

2. I ran a 1/8" balsa sheet inside the fuse from the firewall to the rear compartment. I did this for two reasons:

a) It helped shape the fuse.
b) It strengthened the fuse

I'm going to put hook/loop fastener on it and then build a cover to cover the battery.

3. Instead of simply gluing the landing gear wire to the inside of the fuse, I took two(2) pieces of 1/16" balsa and sandwiched the wire between them. Then I took 1/16" ply and sandwiched the balsa. A lot of 15-min epoxy was used to make sure it was sturdy and well mounted.

4. I'm using an FM receiver on this one. I had one handy. I ran the antenna through and around the inside of the tail-boom. That way no wire shows.

5. I'm thinking of using hinges instead of hinge tape for the controls. Thinking of sandwiching them on the controls with a small piece of balsa. Will let you know how I decide to attach.

While not an upgrade to the design, I did mis-cut the windscreen from the plans. Bob's picks show the side cockpit windscreen cut to be very steep. I actually mis-cut and made it about 45deg. This in turn made the windscreen itself shallower and longer than Bob's. You can see this in my pictures. Especially the ones that show the top of the fuse where the wing joins. There is a long piece of filler balsa between the leading edge and the windscreen. This is wrong...but I'm not tearing it all down to fix it...so I'll live with it.

In the pix, the wing / tail-boom / and horizontal stabilizer are NOT glued together. They're just sitting in place. So if you see anything out of line...that's why. I'll make sure everything is aligned before gluing. I'm planning on covering the wings tonight and making the hatch covers if I have time. I hope to have this thing done by the weekend.

-Eric
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Old Feb 05, 2009, 09:25 PM
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More build pix....
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Old Feb 05, 2009, 10:11 PM
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Nice efether,

I was thinking of building this one. I think it will develop a following.
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Old Feb 06, 2009, 10:12 AM
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This would be a cool build. What are going to use to power it? Prop/batt/esc size?
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Old Feb 06, 2009, 10:29 AM
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Quote:
Originally Posted by Coop
This would be a cool build. What are going to use to power it? Prop/batt/esc size?
Well, with tough economy comes cheap motors

I'm using an ELE I got from BlackdogRC a while back. The EC28PM

http://www.blackdogrc.com/blackdogrc...ies.jsp#EC28PS

Which will be attached to a CC Thunderbird-18 ESC and then I'll be hanging a GWS 6x5 prop. With a Zippy 3S1000 or 3S1300 (I haven't fitted the battery yet). According to BlackdogRC, this should produce about 19oz of thrust at 14A. I'll run the watt meter once it's done. Assuming 14A and the 3S1300 pack, I should be looking at flight times of 5.5 minutes (assuming WOT the whole time. Flight Time = Pack capacity (Amps - not mAh) * 60 / Amps used). I figure half throttle flights since AUW should be close to 12 ounces (minus paint and covering). I'm planning on 10 minute flights.

I'm also thinking of making a secondary hatch under to hold the FlyCamOne camera. Will have to see how the balance works out...but it is an obervation plane, and I think it would be cool if I could rig the camera with a servo tied to the rudder channel -- to move the lens --. I'll wait for it's completion before testing this idea...I made the hatch covers 100% removable, so replacing it with a specialized one for the FlyCamOne would be a non-issue if I can get the balance right.

-Eric
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Old Feb 06, 2009, 10:44 AM
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Wasnt this model painted not covered?
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Old Feb 06, 2009, 10:53 AM
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Quote:
Originally Posted by Coop
Wasnt this model painted not covered?
Gotta cover the wings. Then paint the whole thing.

-Eric
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Old Feb 08, 2009, 01:21 AM
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She's done. I'll post pictures, and maybe a video of her maiden tomorrow. Here is some info --

Weight -- 12.6oz
AUW -- 14.6 oz (includes 3S1000 pack)
Power -- 158 Watt
AMPS -- 13.9 Amp

Estimated flight time -- 7.5 minutes at 1/2 throttle.

Power-to-Weight -- 173 Watts/lb.

Should be interesting

She weights more than the designer's plane for a couple reasons...

1. I'm using a bigger engine
2. I'm using a bigger ESC
3. I covered the entire airplane in finish-cure epoxy. Figured it would strengthen the entire plane, but especially the foam and spackle I used for filler.
4. One coat primer, one coat color, one coat clear-coat.

-Eric
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Old Feb 08, 2009, 12:06 PM
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Okay...a few comments about the pix --

1. I ran out of OD paint...there are a few thin spots. I know...I may fix them when I get back to the store...but in the mean time...think of it as weathering.

2. I ran out of clear-coat. The controls are not clear-coated. Oh well....

3. I went with Hinge Tape instead of hinges. Why? Wanted to get it done and it was faster...and it covered part of the controls so the lack of clear-coat wasn't as evident.

4. The wings are not 100% 90-degs to the fuse. Was a M-A-J-O-R pain to get them aligned while 5-min epoxy kept wanting to leak out of the seams, while trying to keep the control rod to the elevator in place on the servo. Looking at it...I'd say its about 2 deg off. I can live with that. The important alignment...the horizontal and verticals to the main wing are straight...so it should fly straight.

5. Please don't criticize my covering job. I stink at covering wing-tips...those curves screw me up.

6. Be advised...trying to cut out windows from shelf-paper....NOT EASY. Did my best...not the best I've ever seen...but looks good enough to me.

7. Yes...I know the rear wheel is yellow. As I said...ran out of OD paint. Might paint it black....

8. I started building a hatch cover for the battery...may finish it...might not.

9. FYI...the Zippy 3S1000 pack fits the well perfectly. TP 3S1320 should fit as well...will test that one out later.

10. She's nose heavy. Not a lot...but she is. Should be able to add the FlyCamOne in a replacement rear hatch cover (specially designed with a servo, etc. Next part of this build) and keep her balance. More to come one that one.

11. I don't have an US Army decals...nor the means to make (I have a laser printer...not a inkjet). Will keep my eyes out for them.

12. I'm hoping to maiden her today on 25% for the ailerons and 60% for the elevator. No expo. The servos I put on her have given here MASSIVE throws for the ailersons....I'd say about 60deg. W-A-Y too much for this bird on her maiden...so have them tamed down. High-Rates are still 100%

-Eric
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Old Feb 08, 2009, 12:21 PM
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Eric, it looks great and am looking forward to your flying report. I just downloaded the plan and am thinking about scaling it down to about a 14 - 16" ws.
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Old Feb 08, 2009, 07:46 PM
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Flight Report

Not the best maiden in the world ... had winds upwards of 10 MPH. I did get it up and down okay (although on landing I did bounce it in...no damage). The wife did video it...but it's not the best...I'm editing now. I may post to Youtube if I can make it viewable.

As for the plane...I think it needs the following tweaks --

1. Re-align control surfaces. Something is off
2. Put a bigger prop on it. Feels under powered at less than 1/2 throttle, and it loses speed quick. Be aware.
3. Put gyro in it on the ailerons to help stabilize it. I like Gyros in my planes...makes them more stable and wind resistant.
4. Put a little left thrust angle on it ... it wants to crab to the right. It could have been the wind....will fly again in zero wind before I do this one.

-Eric
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Old Feb 08, 2009, 10:21 PM
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Here's a video of her Maiden. I know ... it stinks, but better than nothing. I have already made the adjustments mentioned above (minus the thrust angle. And no, I didn't reduce the Aileron size). Hope to fly her tomorrow morning ... suppose to be in the 40's with no wind.

Boeing L-15 Scout RC (3 min 3 sec)


-Eric
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Old Feb 09, 2009, 09:38 PM
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Okay, I got out and flew it again today. **MUCH** better. I'm throwing a GWS 8060 (8x6) prop now, and with the gyro on board....a different plane. Simply flew AWESOME!!!!!!! I went through three(3) packs today --

Zippy 3S1000 = 11 minutes (800 mAh refill from charger)
TP 3S1320 = 12 minutes (I brought it down...still had power to spare..850 mAh from charger)
Zippy 3S800 = 6 minutes (400 mAh on charger)

Flew great great great!!! Couldn't be more pleased. Rolls were nice and axial. Inverted flight was as it should be...requiring a touch of down elevator to maintain level flight. I still have a slight port crab, which is from a straight motor mount...no 3% of right thrust. I'm fixing that tonight. It has great high AOA flight, and I've gotten the landings down perfect.

Recommendations to builders --

1. You want about 25-30deg of control throw on the ailerons. More than that...gets too twitchy! I am now using 40% expo. HUGE difference.
2. If you can get your hands on a gyro...use it. My third flight today was with winds like the video above. 10+ MPH gusting. The Gyro made the wind a non-issue. It literally took off in about one(1) foot of take-off roll. I goosed the throttle..it leapt in the air.
3. Mount the firewall square, and add one (estimated) washer on the port side to create some right motor thrust.

Also, if your going to attempt to scale this plane down, be aware that the plans printed on 24"x36" create a battery well that can accommodate a TP 3S1320. If you go much smaller...you'll either have to redesign the battery tray or use a smaller battery.

I'm going to try and get some more video and post it. I'm building the hatch-cover for the FlyCamOne tonight...hope to have some inflight video tomorrow, with possible ground based video as soon as I can get the wife out there to do it.

To all reading....this has quickly become a very nice airplane that I'm very please to have spent the time and $$$ making. Just make sure all controls are aligned correctly, you have about 30-40% expo, and enough power.

-Eric
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Old Feb 10, 2009, 10:49 PM
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Well, I got the FlyCamOne-2 mounted to a replacement hatch cover. Because of the design of the L-15, the hatch cover lies below the wing, so the CG sits just right. I made the cover so it locks in place in the front and the hatch cover latch secures it in the rear....nice and solid.

This is a temporary design...I want to build a cover that has gimbals and two servos so the camera can move left/right up/down. First things first, though...I have to get this stupid camera working more than 1-3 minutes before it cuts off due to the battery voltage drops. I'm about to crack the case and solder a battery lead off it and hook it up to a 1s pack.

Here are some pix...and a video made via this set up. Please notice how stable it flies and how well...even with an additional 1.6 ounces added.

L-15 Scout Aerial Video - 1 (1 min 12 sec)


-Eric
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Old Feb 11, 2009, 06:55 AM
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Nice job Eric. I have been tempted by this one myself.

I wonder how your model would do on a 2S pack. You clearly have more than enough power on 3.

Thayer
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