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Jan 17, 2017, 08:27 PM
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Captain Dunsel's Avatar
Very fond memories of seeing a Sterling D-VII, painted as per the box (kit prototype, maybe?) at Rhinebeck. That was circa 1966-67, when The Mission included chasing free balloons... The model apparently was painted in Pactra Fokker Red dope (hard to mistake!).

That day, the balloons were drifting from the field centerline, back over the stands. More than one model wound up overhead as they chased the balloons (I believe that was the last year the balloons were left untethered).

I was standing along the abrupt, slight rise, when the model flew almost overhead. He pulled hard up, trying to get the balloon, maybe 20 feet overhead. The main gear visibly hit the balloon, making it bounce, then the model fell over backwards and barely rolled out in time. Obviously, it made an impact in my young mind!

CD
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Jan 18, 2017, 05:37 PM
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CD you may well have seen the first Sterling DVII. The Flying Models cover was taken at the Toledo show, and it appeared in June 1968 issue.

I installed servo mounts. The rudder and elevator servos fit between the gear legs and are accessed from the bottom. The throttle servo is on the fuselage side, up under the cowl, accessed through the bottom lower wing opening. After test fitting the servos, I realized I should have put all three between the legs. A 180 degree bellcrank would have made it work. Well, maybe next time. Picture shows the servos sitting in place.

Jim
Jan 22, 2017, 09:15 AM
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Top deck sheeting has been applied. The rear decking behind the cockpit is not scale; it should not extend the full width of the fuselage at the stabilizer. I just built it per the plan. The fit of formers and stringers is mediocre.

For the nose I feel I have to make some changes. Sterling shows the nose and radiator (plastic) as one unit. It won't be possible to get the engine out if built per plan. I suppose the radiator can be removable, and I think I could get the engine out. If made that way it would look like an ARF.

So, I decided to split the radiator at the thrust line, making the bottom permanent and the entire top including top cowling removable as a unit. The pictures show the progress.

I used the kit lower nose blocks. These are pretty crude and don't fit well. They needed the obligatory carving. The plastic radiator molding is not as wide as the fuselage; it's almost 1/16 too narrow on each side. The whole bottom will get 3/4 oz glass cloth. It will be needed to cover the sins.

Jim
Jan 22, 2017, 05:36 PM
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Major surgery. The partial formers on the left side have to go. The outer layer of 3/32 sheeting was removed so that a new part line is about 1/4" below where the louvered side panel attaches. That will put the detachable upper cowl part line behind the louvered side panel.

I made up some new formers for the upper cowl. Everything gets fitted to the fuselage, then some stringers, then the exterior sheeting. Once sheeted the opening for the engine and exhaust gets cut out. I hope this will work.

Jim
Jan 25, 2017, 02:33 PM
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The removable cowl is now sheeted with 1/16 balsa. It's going to work out better than I thought and will be an improvement over the permanently attached original. I haven't yet cut the openings for the cockpit, guns or engine. I'll probably cover with 3/4 oz fiberglass before doing so. The width of the engine opening is still a question.

The stab and elevator ended up being completely scratch built. The kit parts included a massive and heavy shaped leading edge 1/2 x 5/8. I just couldn't use it.

It's pretty obvious at this point that the only reason to actually build one of these kits is for nostalgia purposes. Nostalgia drew me in, so I'll keep at it.

Jim
Jan 25, 2017, 05:42 PM
Mumbling in the corner.
flyboy2610's Avatar
I like that cowl idea!
Jan 26, 2017, 09:35 PM
Brighto?
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Here's my Sterling Fokker built in 1968 by my uncle and enjoying its retirement. I recently took it apart for a clean up and inspection to see what storage damage it may have received. With no radio, tank or engine it weighs around 7 lbs. I had considered flying it again but after almost 50 years, I decided against it. If I want a D-VII, there are a lot better ones out there than a Sterling.

Keep it as light as possible and it will be a good flyer, albeit with pattern performance. Looks like you're getting there.
Last edited by Mike Denest; Jan 29, 2017 at 12:40 PM.
Jan 27, 2017, 09:01 AM
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Thanks for those pictures Mike. I have to say your uncle did a fantastic job with the finish. All hand painted, and a great scheme to boot. I can't tell the nose is longer.

I'm trying to cut weight wherever I can. It's close to the time when I start the wings; I can't believe how much wood is still in the box. How is it possible for the two wings to absorb all those sticks? There's 1 1/2 pounds of wood in that picture.

Jim
Jan 28, 2017, 06:19 PM
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The wing pieces are driving me crazy. Each wing has a leading edge, 2 spars supporting the leading edge sheeting, a massive front spar with a soft balsa center section doubler, a rear spar with its doubler, aileron spar, tapered trailing edge and scalloped trailing edge. Sizes are inconsistent, inaccurate, short in some cases, and in all cases bent. Not one of the main spars is usable. The pieces in the picture are seemingly extra; I can't figure where they go.

Credit given to those who have successfully built this kit.

Jim
Jan 29, 2017, 01:43 AM
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JJ, just got one of these kits today and will be following your progress with interest. I will start construction tomorrow. Have you given any thought to putting aileron servos in the wing at the aileron? The plans show about a 1" depth to the rib where the ail nyrod would come out. I know the sailplane guys have thin back mounted servos but do not know the torque value. I guess there are some mini servos that have enough torque but not sure. John.
Jan 29, 2017, 06:33 AM
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Hi John, welcome to the world of Sterling. For motivation here are a few pictures of Sterling D.VIIs - all very well done.

I plan to spend today figuring what to do about the wing spars. The kit sizes are not anything I have on hand, so I'll make up something else. Most of the 1/4 scale versions use the scale location at the sheeting trailing edge for the main spar; a rear spar is then added full length in front of the ailerons.

It seems very possible to use thin servos for the ailerons. The wing rib is indeed 1" high at that point. I'm undecided about the wing servos; I don't want to spend a lot of money on them. Being able to program differential would be nice.

I also determined 6 of the unknown hardwood 3/16 x 5/16 sticks (green gumwood??) in the picture above are for the interplane struts.

Jim
Jan 30, 2017, 12:52 AM
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Thanks for the welcome JJ, my sticks are still bundled and wrapped, the struts are listed as hardwood and appear to be spruce, nothing green. See the pics. Tower has HS-125 thin wing aileron servos with 41.6 oz of torque, 10mm thick for $35, and HS-85 Mighty Micro with the same torque 1.14" tall, or 30mm. Cheap enough, I will get some of the thin wing servos when they get the Williams Bros 5" Vintage wheels back in stock. John.
Jan 30, 2017, 06:40 PM
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Any of the 1/2" wide servos will go in the wing. Here is an HS-81 sitting on the appropriate rib. I decided to use something similar, so holes were cut in the ribs to pass the wires.

Sterling used that two spar system because the spars are used to set the ribs above the table and at the correct incidence for building. The spars sit on 3/4" filler blocks. Because the kits spars were too badly warped to use, I fabricated new front ones from 1/8x1/4 spruce caps over 1/4" square balsa. At the dihedral break I used a ply joiner, then faced it with 1/16" ply.

There does not seem to be any mention of dihedral in the instructions or on the plans. I guess you're supposed to just glue the wing spars to the center section sub spars and expect it to come out. I just made full length spars.

To get the top surface of the wing flat I drew a line representing the top surface of the wing. Then the distance on each rib from the high point to the spar top was transferred to the drawing. This gave me the necessary dihedral. Unfortunately my rear all balsa spar didn't work out; it had to be cut, and will be rejoined with a doubler when I make the panels.

I also junked the kit leading edge method and used a false leading edge keyed to the ribs with a 1/8 square strip. The ribs got cut off in the front and notched for the strip.

So far the center section is glued. Tomorrow, the right panel.

Jim
Jan 30, 2017, 11:19 PM
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Looks good!
Jan 31, 2017, 09:21 AM
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John, your kit is certainly packed differently than mine. All my sticks were loose in the box, and there was no parts list showing what goes where. My kit included a 2x3 inch note indicating the maple center spars were no longer included. 1/8" balsa was substituted, with the observation that the change saved almost 3/4 pounds of weight. I didn't trust the 1/8 balsa, so it was another reason to change the spar design.

Your fuselage is progressing well. When the time came to apply the top deck sheeting, I sanded a bevel down the length of the 3/16 top longerons. This provided a surface for the 1/16 sheeting to glue to. It also meant an overlap out the sides could be left, eliminating the need to accurately cut the sheeting. When sanded flush, I was back to the 3/16 dimension.

Jim


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