Building Depron Dave's OV-10 - RC Groups
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Nov 29, 2004, 10:41 PM
Just Keeping UP

Building Depron Dave's OV-10

Awhile back, there was a short thread anouncing David Penikas' design for a Depron OV-10 using two small GWS EDP50XP motors direct drive. You can see the details, and a flying video here on his web site.

As luck would have it, I was online when Dave had the pdf files ready to sell and I immediately sent my money. I have the dubious honor of geting the first set of plans.

Then I sent an order for Depron to Depron USA.

So, this will be a record of my building experience.

Below is a picture that I stole from David's web site.

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Nov 29, 2004, 10:52 PM
Registered User
I made a similar plane, but using a single EDP50 as a pusher. My WS was 28"....chord was probably slightly less than this one though. What's the AUW supposed to be? Mine was 3.9 oz with 340mAh Kokam pack and flew pretty well... fast and maneuverable.
Nov 30, 2004, 01:42 AM
Just Keeping UP
The wing span on this OV-10 is 24" and the chord is 5 3/16". Dave did not give an AUW and mine isn't done yet. So, I don't know.

I'm well along in the build process, just need to get this thread caught up!

Nov 30, 2004, 01:56 AM
Just Keeping UP
OK, here is my parts layout before making any cuts. If you build one too, make sure that you lay out the wing and Horizontal stabilizer before deciding where to put the other parts on the foam. I used 3M Photo Mount spray adhesive to hold the paper paterns on the foam. This worked very well for me. Removal at the later stages of contruction was very easy.

Nov 30, 2004, 05:15 AM
Registered User
eSmasher's Avatar
I think I am going to enjoy watching this build

Nov 30, 2004, 04:57 PM
Just Keeping UP
Dave's instructions show a great deal of detail, so I'm not going to show each step.

Here are a couple of photos of the fuselage pod.

Dave uses epoxy to glue the parts together. I decided to try foam safe thick CA. This worked OK. I even found that I could use Kicker to speed things up if I used only a VERY SMALL amount on a cotton swaub. Too much kicker on the swaub however, and you'll have a dimple in the foam. When this happened to me, I filled the depression with light weight white filler.

The foam at the front and back of the pod needs to be bent in a fairly tight curve. In order to get the foam to bend, Dave instructs to crease the foam with a puty knife. This worked well up to a point. I was able to bend the foam much farther than the instructions show. However when gluing the second pod side on, I had a lot of trouble with the foam straightening out. The next time I need to make sharp bends in foam this thick (6mm or 1/4"), I'm going to thin the foam in the area of the bend. This should make it easier to bend and less likely to straighten out on its own. For a gentle curve, such as the top of the canopy area, I was able to curve the foam by gently rolling it around a can.

Nov 30, 2004, 06:54 PM
Just Keeping UP


Here's the first place that I've significantly deviated from Dave's plan and instructions. The given way to mount the motors is to make a mount reinforcement with 1/64" plywood at the front of the booms and hold the motor with a tie-wrap (or zip-tie). The plans also show a second layer of foam here, but the instructions don't show it, or mention it. I'm not fond of using tie-wraps for this so I decided to use a small model rocket body tube as a mount for the motors. The BT-50 size is the closest fit that I could find. It's a little large, but a few wraps of narrow strips of masking tape takes care of that. (Standard model rocketry procedure.) With enough wraps of tape, the motor is a tight enough friction fit that I don't think any other means will be necessary to retain the motor during flight.

I cut the tube to the length of the motor and glued it centered into a cut out in the boom. I made sure to keep the motor on the same thrust line.

After the glue set, I cut out the center sides of the body tube for motor cooling as shown in the photo below.

Last edited by nfhill; Nov 30, 2004 at 10:50 PM. Reason: spelling, added sentence
Nov 30, 2004, 09:49 PM
It'll work this time!
The Commodore's Avatar
Dang - that looks cool!

Keep us updated, and good luck!
Nov 30, 2004, 10:16 PM
Lots foam, so little time
Depron Dave's Avatar
That is a great idea!
There is so much cleverness out there.
Dec 11, 2004, 03:38 AM
Just Keeping UP
It may look like I've given up on this, but I haven't. I just needed to work on my Staggerwing project for a while.

I routed slots in the wing per Dave's instructions so it could be bent to the airfoil shape. My groves were about 1mm wide and 3mm deep using a tapered cutter in my Dremel tool. This is a very easy way to make the slots

Next, I glued the carbon fiber strip reinforcing on the bottom of the wing. Frankly, while this strip will keep the bottom surface of the wing from breaking, it doesn't seem to stiffen the wing much: The foam at the top of the wing still compresses enough to let the wing bend easily.

I've now glued the fuselage pod and the booms to the wing. Also the horizontal stabilizer is glued in place. After gluing the wing on, I found out that the wing was very difficult to bend to the desired shape and have it stay there. I think my routed slots were too narrow. Next time I'll route them 4mm deep and 2mm wide. This should make it easier to bend the airfoil shape into the wing without it trying to flatten back out.

Check out the photos. The next steps will be coming soon!

Dec 15, 2004, 01:52 AM
Just Keeping UP
I've made some more progress. I now have the ailerons and elevator hinged. In the plans Dave illustrated how he held the canopy on with a pin and he asked someone to come up with something better. Well Dave, I don't know how much better my way is, but here it is.

First I modified the shape of the hatch. The plans show a large hatch cut out along the canopy outline and a small hatch in the center of the wing over the aileron servo. I decided that since they are so close together that I would combine the two into one hatch and that way I would only need one hatch retaining system. Then I took a piece of foam and made a small 'bar' across the back of the canopy opening and glued a rare earth magnet recessed into it's center making sure that it wouldn't interfer with the installatio of the aileron servo. Next I glued another bar of foam across the back of the canopy / hatch with another magnet recessed into it so it would match up with the first magnet. Finally, I added a small tongue of 1/32" plywood at the front top of the canopy so it fits into a slot in the foam. I completed the system with two small pieces of foam glued to the front inside of the canopy to locate the canopy on top of the fuselage.

You can see the result in the two photos below.

OK, Dave, now you can decide if you like it!

Dec 15, 2004, 04:54 PM
Lots foam, so little time
Depron Dave's Avatar
I like it!
I just received some tiny 1/16" Dia x 1/8" rare earth mags.

I've been trying to figure a better way of cutting the wing grooves.
this is what I've found,
Switch to a Dremel conical cutter will let the depron bend easier
because of the point, not the width of the cutter.
The foam needs a fine stress line to bend. The square end 1/16
cutter doesn't allow this, but you can go back and lightly score
the groove with a hobby knife.

Also packing tape under the wing will hold the shape very nicely!
The L-19 on my bench is all 3mm Depron..DXA power...more on that

The #125 cutter will allow for a 35 degree bend..think of the possibilities!
Well that's what I came up with. The soldering iron was too un predictable
Dec 15, 2004, 07:04 PM
Just Keeping UP

I did use a conical cutter. But, I think it was just too narrow. When I bent the wing the edges of the slot came together before the desired shape was achieved. Next time I will use a wider cutter.

I have a suggestion for the wing spar. Instead of gluing the carbon strip flat on the bottom of the wing, why not slice the wing in two spanwise and glue the carbon strip in vertically? The way it is now the top of the wing just compresses, or stretches, and the wing bends easily. A vertical carbon strip should be stiffer.

Dec 15, 2004, 08:32 PM
Lots foam, so little time
Depron Dave's Avatar
I think so, since the first prototype which was a carbon tube, strong but heavy,
I was trying to keep it light. The wing doesn't flex much in the air. On the otherhand
the verticle spar is a great solution. I went with the flat tow because I have about 200
feet of it.
On the "instruction build" of the A-26 I will try a verticle spar.
If I yank and crank it, I can make certain vowel shapes as it flys.

Last edited by Depron Dave; Jul 07, 2005 at 02:23 AM.
Dec 17, 2004, 04:14 AM
Just Keeping UP
OK, I've got all the control linkages and the servos installed. For the most part, I followed Dave's instructions accept:

When installing the rudder interconnecting wire, I installed the short pieces of control sleeve parallel to the rudder hinge line instead of vertical. It's my understanding that this is the way to minimize binding: if the pivot/hinge lines aren't parallel, binding will result. You decide for yourself.

I've never had much luck putting z-bends in cables and even in wire I get them in the wrong place. So I made short 'L's in 0.032" music wire that were just long enough to use Dubro micro EZ links and silver soldered them to the ends of the control cables. This was especially useful for the ailerons since it made getting both ailerons at neutral much easier.

The rudder linkage is a straight run from the servo to the rudder horn, so I used 0.032" music wire in the cable sleave instead of the cable. This was easier for me.

In my opinion, the design of the control horn for the elavator could be changed to make the installation of the elavator control cable easier. For equal up and down movement in the control surface, the cable must intersect the control horn so it forms a 90 degree angle with a line drawn to the hinge line. The existing control horn shape requires the cable to be parallel to the horizontal stabilizer for equal up and down movement where it attaches to the control horn. This, in turn, requires quite an S-bend in the control cable. If the horn shape is changed so the attachment hole is rotated to the rear (with the same radius from the elevator hinge line as it has now), the control cable could intersect with the horn with the cable running at an upward slant. This would still give equal up and down movement, but reduce the amount of bend required in the control cable. This would make the cable easier to install and reduce friction.

Of course, I didn't think of this until after I had the existing control horn glued in place.

In any case, if you look close in the photos below, you can see my current progress


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