|Jan 01, 2007, 11:27 PM|
Just Another Destiny, with LEAD.
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Soaring USA's Destiny, Built with Ballast Tube
NOTE: Please post any commentary in the slope forum:
And here is a mini-how-to on the ballast tube build:
My brother Mike had a second Destiny that he bought for a back up to his original Destiny, from Bob at:
He had the extra plane for over a year, and I suggested that he build it up, so that it could truly be the back up to his original 4-year-old Destiny, or at least, the other way around.
My brother is a fairly good pilot, and flys his Destiny more than any of his other planes, so his has been repaired many times. We have found that the plane is an extremely good value, but I figured I could make it a little bit better with a few simple modifications.
First off, we both agreed that the plane was a little bit light for really high lift, and the turbulence that often accompanies high lift into the landing zone.
So, the inclusion of a ballast tube was a high priority. We wanted to get the plane over 30 ounces ballasted, but stay close to 20 ounces empty.
Also, we wanted to avoid having to take the wing off to ballast. Heck, my brother, Mike, hates to take the wing off at all! So, ballast would have to be inserted through the canopy.
To help the fuselage cope with the extra strain of ballasted landings, some Kevlar reinforcemnets to the front area, from the nose to just aft of the wing saddle would definitely help out. I had some light Kevlar, that I bought right here on RC Groups, that is about 1.4 or 1.8 oz/yard weight. It would work nicely.
Since the plane comes with two "snakes" for the v-tail already installed, we figured it was actually easier to install two tail servos than one bigger one. The weight saved would not be much with one servo, since they are up front, and two servos give redundancy, as well as a little rudder mixing for light lift days.
We also wanted to have easy access to the receiver crystal for channel changes, just in case Mike ever traveled to fly at a busier slope than our usual low-traffic home slope.
I started on the fuselage. First, I used some of that light weight Kevlar to reinforce the fuselage. The Destiny is a tough plane, but no plane is completely "Mike-proof."
First, I marked the pattern of several pieces by wrapping it around the outside of the fuse. I cut out the 5 individual pieces, and sprayed them lightly with 3M77 spray. I let the 3M77 spray dry somewhat, for a few minutes. They were tacky, not wet.
Then I placed them in position inside the fuselage. When I had them smooth and close to perfect, I mixed up 24g of West Systems resin, and used an acid brush, on a balsa stick to sparingly apply it into the Kevlar.
Once it was all "wet out", I blotted the excess resin gently with paper towels, and set it aside to dry.
Here are some picures:
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|Jan 01, 2007, 11:53 PM|
The fuselage gear would end up consisting of:
(1) 4 cell AAA 700 MaH battery pack,
(1) Hitec Electron 6 receiver, and
(2) Hitec hs56-HB servos.
(2) 12" servo extensions.
The wing would get (2) HS-125 servos for the ailerons.
All of the above parts, even the battery, were also purchased at:
After pondering a long while, I decided I could get a 5/8" diameter ballast tube, 180mm long, mounted in the fuselage, under the servo tray, with the loading area accessible from the back of the canopy. I think I can!
That would allow us to use 1/2" copper pipe, cut and filled with lead, for the ballast slugs. I bought a 2' piece from Home Depot, and used it to make the fiberglass ballast tube.
Here are some pictures:
|Jan 01, 2007, 11:57 PM|
Next was the tail, which needed the control rods fitted and epoxied into the ruddervators. I hate this part on every build!
I used strips of fiberglass to reinforce the epoxy, kinda like a safety net.
After the epoxy cured, the excess glass was sanded off the ruddervators.
|Jan 03, 2007, 12:24 AM|
While that was drying, I turned my attention to the wing, specifically the servo covers. It is easy to trim the covers properly, but easy to mess up, if you don't know how to do them.
Here is what I do:
|Jan 03, 2007, 12:36 AM|
Next, I snipped and bent a hold down wire for the canopy.
I tacked it to the canopy with microballons and thin CA in one spot to test if it would work or not. Once I was happy with that, I mixed up some West Systems, and split it into two very small batches.
To one batch, I added some West # 406 Collidal Silica (any thickener with work). You don't want it too thick.
With this, I made a nice fillet about 2" long and 1/2" wide on the wire. I wanted to ensure that the glass I was going to add would not have any voids under it.
After I was happy with the quantity and shape of the fillet, I layed on the glass patch, (about 2" long, and 1.25" wide), and applied the plain West Systems Epoxy over it.
I set it aside to cure overnight.
|Jan 03, 2007, 12:48 AM|
Here is what the nearly finished fuselage looks like.
Balsa ramps were fashioned to support the push rod housings. A strip of wood was glued behind the ballast tube opening to help keep the ballast slugs from slipping back into the tail boom while putting in lead at the slope.
The ballast consists of 9 pieces of 1/2" copper pipe (5/8" OD) that are 20mm long each. The 180mm total should weigh very close to 13.5 oz. Spacers will be fashioned from 5/8" dowel, for the times that partial ballast only is needed.
|Jan 03, 2007, 08:28 PM|
The holes for the servo wires need to be drilled in both the wing saddle of the fuselage, and the underside of the wing.
A rib that the bolts pass though runs from the leading edge of the wing, to the trailing edge. Because of this, there will need to be two seperate holse in at least the underside of the wing.
The fuselage can either have two seperate holes for each individual wire, or one larger one. I choose two smaller ones. Keep in mind that the holes in the fuse will need to be big enough for the connector you use, to pass through.
Not so with the wing. If you are willing to take the plastic male servo connector housing off the wires, then the holes in the wing skin can be very small. The servo wires can be passed through, then the male plastic body re-attached to the wires.
I posted some pictures. The natural order is to do the wing first, then try to match the location on the fuselage. Tape is your friend, and can be used to map out where the matching holes in the fuse need to be. You should be able to follow along in the pictures.
|Jan 03, 2007, 11:49 PM|
A little more work got done tonight; the plane is almost done!
Skipping ahead a bit, it looks like it will take about 1.2 ounces of nose lead, and weigh about 24 oz all up. That makes me happy. There have been lighter Destiny's, but the 125's in the wing weigh a bit more than some other minimal weight servo choices. And that is with two tail servos and a ballast tube...
Tonight, I wrapped the 125 servos with two layers of masking tape, then sanded the top lightly where the servo was to glue to the upper wing skin. If the servos ever need removal for service, they should come out easy enough by cutting the tape.
Had the plane's wing not been the beefy wing skin layup that Valenta is known for, I would have reinforced the servo mounting area with some fiberglass and resin before gluing them in. After I sanded the tape lightly, I wiped the tape off with a paper towel with a little acetone in it, to remove any dust and release agent that might be on the backside of the tape.
The servo wires had to be run to the holes near the root rib of the wing BEFORE I glued the servos in. I took the black plastic connector off the wire ends, and taped the ends to a piece of thin cable flexible push rod that I had snaked through the wing, from the center hole to the servo bay.
I use a small piece of masking tape to bind the servo wires to the pull cable. Then I carefully worked the wires through the wing, and out the center hole.
After that, I put the black plastic connector back on, making sure to get the order correct!
Now I was ready to glue in the servos.
I used 15 minute epoxy, and mixed in some West Systems 406 Collidal Silica to make a medium thick paste, about like mustard consistancy.
Then I slathered the servo surface with the epoxy/filler, being careful around the top of the servo where the output shaft and horn are.
Into the wing they went, and the yoke was snapped onto the control horn ball to help hold the servo against the spar, and so that I could see the linkage was straight.
I tried NOT to glue the servo to the spar; the plane will not be DS'd, and it will be easier to get them out later that way.
I also finalized the wiring in the fuse, except for any battery wires/switches.
I took some pics of the tail servos at max throw, to give an idea of how little the push rods have to bend while being actuated... It looks great to me.
|Jan 06, 2007, 02:38 PM|
Here is some of the last of the build.
I have yet to trim, and fill the ballast jackets with lead, and make some wood spacers.
I also intend to shim up the LE of the V-tail about 1/16" to start for the maiden. I hope that Valenta eventually fixes this small decalage problem. Even so, the plane is a bargain, and flies well after a little tuning. This plane is fully worth a little effort.
I have one more aileron servo cover to fit, and I think that I might glue those on lightly with some contact adhesive, rather than tape them on.
The plane is on the charger now....
Where is the wind!
|Jan 06, 2007, 04:17 PM|
Just a couple more pics.
I found some nylon 4mm x 12mm cheese head slotted screws, and the 7-7.5 mm head diameter fits into the cups in the wing PERFECTLY.
I know that some will doubt the security of the nylon fasteners, but I think that if they get replaced regularly, they will be fine, and offer a big measure of damage control...
One picture includes the small extension I made for powering up. It goes between the reciever and battery, so that the reciever port isn't constantly being plugged into and unplugged. I thought of adding a microswitch, but I'd still have to unplug it to charge. And, it's one more part to fail.
The last installation will be making the ballast slugs.
|Oct 21, 2007, 12:29 AM|
We flew Mike's Destiny some more at the local slope in medium lift. He felt that it wasn't flying quite as good as it should, so we added a couple layers of electrical tape under the v-tail LE, in addition to what was there.
What a difference! The plane came alive, and was cruising much faster.
Moral of the story:
|Feb 12, 2009, 07:57 PM|
You'll find answers here:
As mentioned in my first post, and post #9, I wanted to keep this a "clean" build thread, so I will delete and re-post your question there. Please keep all correspondence there, not here. Thanks,
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