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Old Jul 22, 2014, 07:36 PM
Team JR
Doug Cronkhite's Avatar
San Diego
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Stream Build Log

So after a few PMs from my posts in the original Stream thread, I've decided to do a complete build log on my new Stream. There's really nothing magic in the way this is done, but often times it helps to have pictures and words for people when they're cutting into their $800 airframe for the 1st time.

To give credit where it's most definitely due, most of my build methodology comes from Oleg's Validol build instructions, located here:

http://olgol.com/Validol/build.html

Anyway.. here we go.

I start with the wing, since the top drive install is easily the most labor intensive part of the build. The bottom of the Stream wing has the servo locations clearly molded.

I use blue masking tape to outline the cutout. This gives me an easy visual reference against the black carbon wing, as well as a barrier of protection from the knife blade wandering outside where I want to cut the pocket. You want to leave only 2-3mm border around the edge of the pocket. When you cut into the wing's surface, do so lightly. It should take a couple passes of a SHARP x-acto blade to get through the skin and you should NOT go too deeply through the foam. I use a new blade for this to be sure it's sharp enough.

Once you've cut through, use the tip of the knife blade to start peeling back the skin only. Don't worry about removing the foam just yet. You want to just remove the skin at this point.
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Old Jul 22, 2014, 07:40 PM
Team JR
Doug Cronkhite's Avatar
San Diego
Joined Feb 2002
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Now that you've peeled the skin away, you need to remove the foam from the servo pocket. What I do is take the knife blade, and turn it around putting the sharp end into the handle leaving a squared-off section sticking out. Using this flat "blade", I slowly scrape the foam out of the pocket.

Go slowly here. Use your hand on the top surface of the wing (the back side of the pocket) to feel the pressure you're using to scrape. This helps ensure you're not pushing too hard and potentially poking through the top skin. When you're done, you should be able to see most of the black wing skin.. You really need to get all of the foam out of the pocket or the servo arm will hit the cover when it moves. There really is no extra space here.
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Old Jul 22, 2014, 07:44 PM
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United States, AZ, Tucson
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Look forward to the build. Always helpful to see other people's setups.
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Old Jul 22, 2014, 07:45 PM
Team JR
Doug Cronkhite's Avatar
San Diego
Joined Feb 2002
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On the Stream, the holes for the servo wires are often just outside the boundaries of the servo pocket biased towards the leading edge of the wing. I use the sharp end of the x-acto blade to lightly pick the foam out to find the servo wire channel. You can see it here in this picture.
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Old Jul 22, 2014, 08:06 PM
Team JR
Doug Cronkhite's Avatar
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Next, I take a piece of tape and use it to mark a line between the servo wire channels to show me where to cut into the center of the wing. I use a sharpie to draw the hole I want to cut out. As the saying goes, Measure Twice, Cut Once.

Using the same process as before with the servo pockets, I use several strokes of the knife blade to cut through the wing skin. It's going to be harder here due to the resin used to join the wing, so be extra careful. Once you can lift out the small piece of wing skin you've cut, I use the knife to carefully pick out the foam and reveal the center of the wire channel.
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Old Jul 22, 2014, 08:44 PM
Team JR
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San Diego
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Next up comes more of the scary stuff. Cutting the slots for the pushrod exits in the top of your wing. It's actually pretty easy, and once again, take it slowly.

For the Stream, I measure out 101mm from the center of the wing mount bolts, and draw a line 20mm long on the ever popular blue masking tape. This marks the outside edge of the pushrod cut line. Do this for both sides of the wing.

Using a sharp x-acto (replace the blade if necessary), cut the skin using 3 or 4 strokes of the knife. I like to start from the trailing edge and go forward here because of the lack of support at the trailing edge of the wing. You're much less likely to have a problem with the skin breaking away where you don't want it to. Once you've cut through the skin, then make a parallel cut about 1mm inside of the first cut to create the slot for the pushrod. I intentionally cut them slightly under-size, and then open them to fit with a small file.
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Old Jul 22, 2014, 08:52 PM
Team JR
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Now take the piece of wire that comes in the kit for your flap pushrod, and using the slot for alignment, slow twist it like a hand-drill bit, and push it into the wing. Once it's into the foam a bit, verify your angles to ensure you're going to hit the servo pocket at the outer edge. If you've measured correctly, this is actually pretty easy to do. I used braces and pieces of wood to hold the angles on the 1st Stream I built, but went free-hand on this one without any issue.

You're going to need to clear a bit of foam here anyway to get the pushrod into the wing after bending it, so don't be too concerned about hitting the hole perfectly.

More later.
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Old Yesterday, 12:46 AM
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Next up is the slot for the control horn. I purposely cut this one over-sized in width to give me a little room to make sure things line up correctly. This also ensures there will be movement room for the glue to get down into the slot. DON'T GLUE ANYTHING YET. We're not ready.

Make sure you offset the horn about to the outside (wingtip side) of the pushrod slot to account for the bend in the wire or it'll bind pretty badly.
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Old Yesterday, 12:52 AM
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Now you'll need to prepare the servos. This is extremely important so please take note.

First things first, you'll need to ensure your servos are matched exactly at the neutral point. If you don't, you'll never get the flaps to move in unison. Offset the arm slightly towards the leading edge to give you a bit more travel for brake flaps. 15-20 degrees should be plenty. However much you offset this, MAKE SURE THEY'RE THE SAME. Also make sure your travel direction is correct at this time.

The servo arm needs to use a hole 4.5mm from the center of the arm. Any longer and you run the risk of hitting the cover and causing binding. The Airtronics 94802s have an arm supplied with the hole in the correct location, but the KSTs do not. So I had to drill a new hole in the arm. Not hard, just something to be aware of. Also, it appears the KSTs have an even number of splines on the output shaft, so there's no way to make small adjustments by flipping the servo arm like with most other brands.

Last update for tonight. I was going to glue everything in and secure the servo but I broke the pushrod wire trying to bend it and I don't have any more of the correct diameter. I'll grab some at the local hobby store tomorrow and continue the build tomorrow night.
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Old Yesterday, 06:36 AM
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Joined Apr 2010
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Hi Doug
Thanks a lot for showing Your build.
I have 2 questions.
How did You make hole (dril) under the skin for servo wires (for reciver contact)?
I mean on hole inside the wing throw foam- from servo pocket to the hole on center of the wing?
Also while cutting that hole for the servo wires... it is just foam inside?- no spar, or balsa inside to must cut thow- it is just foam?

Thanks and enjoy new model :_)
Best, boris
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Old Yesterday, 07:15 AM
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Following along with interest. I'm just a few days ahead of you. Curious to know what servos you will be using in the pod?

@Boris. The servo channels for the wires are already in the foam just slightly ahead of the servo pocket locations [50 mm back from the LE and 70 mm long either side of the wing panel joint]
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Old Yesterday, 11:23 AM
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I'll be using JR DS285s in the fuselage.
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Old Yesterday, 11:35 AM
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I like it, Doug. Sometimes the way people explain things is easier for others to understand. I'm not saying Oleg didn't do a good job. I just like the way you are explaining it better. It adds a level of clarity for me. For me, TD installation is always intimidating which is one of the reasons I bought my Polaris with pre installed wing servos. I won't have that luxury with the CX4 TD's I just put on order.
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Old Yesterday, 11:37 AM
Time for me to Fly...
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Quote:
Originally Posted by Doug Cronkhite View Post
I'll be using JR DS285s in the fuselage.
Those are my favorite servos. Wish they made them thin enough to use in the wings. I haven't been very happy with the Hyperions and my 94802's are pretty loud.
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Old Yesterday, 11:43 AM
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Quote:
Originally Posted by DLGjunkyard View Post
Following along with interest. I'm just a few days ahead of you. Curious to know what servos you will be using in the pod?

@Boris. The servo channels for the wires are already in the foam just slightly ahead of the servo pocket locations [50 mm back from the LE and 70 mm long either side of the wing panel joint]
Thanks
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