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Old Apr 03, 2011, 10:44 AM
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Build Log
Mountain Models DL-50 Build

Hi!

I got a Mountain Models DL-50 a few weeks ago, and it took me that time to have it almost complete-I take my time to build and complete small steps per day.

Here is the model as it appears today:
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Old Apr 03, 2011, 11:00 AM
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The fuselage was very easy to do. The pieces interlocked well and was a quick build. I found fiberglassing the fuselage much easier than doing it to the wing. I sprayed a light coat of 3M77 on the fuse and then attached the fiberglass with Polycrylic, first to the bottom and then to the sides. After this, I made small slits to the glass around the nose so it could settle well around the nose cone.

I glassed the wing as per instructions. First I joined the wings and then applied the required reinforcements (carbon fiber tape and glass darts) and then I applied the glass over the wing using Minwax Polycrylic. It took me a few days to do this.

The hardest thing was to attach the plywood wing reinforcements-I had to hold them for a few minutes until the epoxy started to cure. I did apply them as instructed-half an inch from the leading edge. However, this caused the leading edge to be a bit too far forward so I had to modify the front wing saddle as shown in the photo. If I did not, the decalage would have been off. I did double check and the reinforcements were as instructed, but by modifying the former the wing holes lined up with the fuse ones:
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Old Apr 04, 2011, 11:39 PM
capnkids
USA, CA, Fresno
Joined May 2008
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I will be starting my DL 50 as soon as I can finish off a couple of things. Do you feel like it is best to build per instructions nag modify the wing saddle like you did or should the wing reinforcements be moved?

Rich
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Old Apr 05, 2011, 11:28 AM
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Good for you, I have alot of fond memorie's of building and flying mine. I vacuume bagged my wing's. Later when I flew it some one said it had to be the highest launching DL-50 he'd ever seen, and I didn't use no stinking polyurethane either.
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Old Apr 05, 2011, 08:28 PM
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I think that the instructions are written as they are for a reason, but if I were to build the plane again, I would move the wing reinforcements just a tiny bit forward than the instructions specify. Again, I placed the reinforcements according to the instructions (1/2 in from the leading edge) but this resulted in having to modify the front wing saddle to accommodate the wing without messing up the decalage.
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Old Apr 05, 2011, 08:33 PM
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I just finished installing the tail feather group into the pod. The instructions did not specify the exact placement of the front of the boom relative to the front wing saddle. I called Mountain Models and I was told to stick the pod in so the front was 1/16 from the front wing saddle. The photo below shows what this means:
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Old Apr 05, 2011, 08:37 PM
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Another tricky step came: aligning the tail feathers to the wing dihedral. After making sure that the alignment was proper, I glued the boom to the holes of the fuselage formers using thin CA. I plan on reinforcing this by adding just a little bit of 30 minute epoxy-just enough to make fillets. I did the same with the tail feathers-attached them with thin CA and then added a fillet of 5 minute epoxy.

However, I noted that after bolting the wing, the wing centerline (where the wing halves are joined) was a bit off the carbon boom centerline. I hope that this does not really affect the flight characteristics. Applying the wing reinforcements was the trickiest part for me-more than building the other parts of this plane.
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Old Apr 05, 2011, 08:42 PM
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So, as of today, the plane looks like this (picture below). All I need to do is to install the throwing peg and the radio gear. I got a Futaba 616FFM 2.4 GHz receiver and 2 Futaba S3111M servos. As for the battery, I ordered an ElectriFly 2/3 AAA 4 cell 4.8 V 350 mAh one The black piece on the wing is the throwing peg, already covered with carbon fiber tape. The airframe as pictured weighs 4.4 ounces (2.6 for the wing and 1.8 for the fuse/carbon boom/tail feather unit).

For the tail reinforcements, I glued the glass using thin CA, and I used epoxy to install the glass hinges.
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Old Apr 07, 2011, 12:44 AM
capnkids
USA, CA, Fresno
Joined May 2008
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Thanks for the input. It is looking good.

Rich
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Old Apr 14, 2011, 02:33 AM
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Well, it is back to building. I got the battery today from Tower Hobbies and now I could start the radio installation. First I made sure that the servos were working and centered, and then I removed the extra servo arms. Then I wrapped the servos with packing tape, which I cut flush to the servos. After this, I sanded the packing tape to make sure that the glue provided a good bond. The photos show the radio gear I am using, the preparation of the servos, and the radio installation. I haven't installed the battery yet.

I glued the servos to the fuselage with goop, because I read in a build thread that the rudder servo came off when using CA glue (source: http://www.rcgroups.com/forums/showt...=355107&page=3) after several tosses. I attached the rough velcro for the receiver to the fuselage with Goop just to be safe. Then I attached the smooth velcro to the receiver (using the velcro's own adhesive) and then pressed this to the rough velcro. I haven't attached the wires to the servos or the control horns yet.
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Old Apr 14, 2011, 02:53 AM
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After this step, I inserted the wires into the fuselage former holes and then I inserted the orange plastic guides. I made sure that these guides were aligned and straight, and then carefully glued them using CA glue. I used a couple of drops and let the capillary action take care of the rest. The following photo shows the triangular balsa piece that was created according to the instructions. This balsa piece is to help the orange guide align with the rudder control horn.
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Old Apr 15, 2011, 09:02 PM
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I finished installing the entire radio gear. The photo below shows the result. All I need to finish the kit is to install the carbon fiber tape reinforcements to the throwing peg. So far, without those reinforcements, the weight is 7.1 ounces.

As for the radio, I added a micro switch harness. It was a bit tricky to install the radio because of the rather cramped space of the fuselage, but now that's done. The plane is already balanced at 2.75 in. from the leading edge, as per instructions.
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Old Apr 18, 2011, 01:34 AM
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I am practically done with the plane-all I have to do is to install the carbon fiber tape reinforcements to the peg. This evening I took the plane for testing near the Rose Bowl. I threw it javelin style and at first it veered to the left. After a couple of trim adjustments, it flew straight and true. I set the throws according to instructions.

Next I did very gently side arm launches and it respoded well-I did not perform full discus launches because the peg is not yet reinforced as per instructions. I am waiting for extra carbon fiber tape to arrive.

The plane was very responsive. I also have to add the light coat of lacquer to the tail feathers.
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Old Apr 25, 2011, 01:28 AM
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The plane has been finished last Friday-the carbon tape reinforcements have bee installed using 30 minute epoxy.

Test flights were conducted next day. The plane nosed down hard after attaining altitude but after a search in RCgroups, the suggestion was to move the CG back. This was done.

Today I tried again. With the CG in its new position (as specified on the plans, 2.75 inches behind the leading edge), I conducted glide tests-first a gentle toss to establish the new trims. Then javelin launches were done.

Then I performed several full discus launches. On one flight, I was able to catch a thermal. The plane is an excellent ship to learn DLG-this is what I am doing now-learning to throw DLG style.

I don't have to establish any prelaunch rudder settings, but I wonder if I can do this to the elevator.

Any suggestions regarding how to attain more altitude are welcome.

Thanks.
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