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Balsa USA 1/3 Scale Fokker DVII Kit Build

Started by Lane C., December 25, 2020, 07:12:08 PM

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Lane C.

February 27, 2021, 01:05:51 PM #30 Last Edit: March 09, 2021, 06:25:19 AM by Lane C.
Started the fuselage today with a bit of pre-assembly of the forward parts. Plywood parts get butt-glued and balsa parts get laminated.

After the 1st plywood parts set is glued up while pinned down on the plans, the 2nd set is built on top of that one to keep them matched. Waxed paper in between the two sets.
Current Build = 1/3 BUSA Fokker DVII

Lane C.

Finally got to gluing up the parts in the last photos. I had to make at least one change to make the parts match the plans. I suspect it's the plans that are off for some reason. Laminated the group of 4 forward fuselage parts and then laid them on the plans and glued them together. After that, laid some waxed paper down and built the 2nd set over the 1st. Then, laid one side down on the plans and added the top and bottom longerons, but nothing glued yet. Even the longerons are laminated! The 1/4 DVII did not require this extra work, but the 1/3 DVII is quite a bit larger and heavier. But you'd better measure twice and glue once on the longerons as once you have glued them in the required curve, they are locked in. But, with the addition of some substituted Basswood strips for added strength, they are very solid. The curves in the fuselage are not that steep and you can easily shape the longerons without any problems - before you glue them. Once one fuselage side is glued down, the other side can be built on top of it. There is no danger of building TWO Left or Right sides yet. But once this part is done, you want to make sure NOT to build two lefts or rights. And, trust me, --it happens if you are not paying attention!
Current Build = 1/3 BUSA Fokker DVII

Lane C.

March 06, 2021, 11:26:18 PM #32 Last Edit: March 09, 2021, 06:37:09 AM by Lane C.
Got one side glued up. Next I'll build the other side on top of this one.

On the question of tail incidence, I went with +2 deg over and above what was on the plans. I laid that out with a large protractor on the plans and then laid the balsa right over that line. The +2 deg incidence will help keep the DVII from climbing on power runs as a flat bottom wing will generate more lift as it accelerates vs a symmetrical wing. The added incidence will keep the tail up and nose down. Also makes the tail come up early on takeoff, so back pressure on the stick is required to keep the prop out of the dirt.
Current Build = 1/3 BUSA Fokker DVII

Lane C.

Built both sides. Then added the plywood doubler on both sides. This is where you must be awake or you will build two LEFTS or two RIGHTS! Ha. I think I got it correct. The plywood doublers goe on the inside of the frame.

Next to last pic is the first plywood doubler flipped over after glue has setup.

Last pic is the basswood strip after being laminated/added between the 2 balsa longeron strips. Adds lots of strength. Basswood is not part of the kit.
Current Build = 1/3 BUSA Fokker DVII

Lane C.

March 09, 2021, 08:00:29 AM #34 Last Edit: March 09, 2021, 08:05:06 AM by Lane C.
Went out this morning to check the glue up. Looks good. Should have glued in the hardwood block for the A Strut before adding the plywood doublers. Oh well, they are in there just the same. Check the A Strut fit after drilling the holes in the blocks. Glue the blocks in and then drill thru the doubler after the glue is set. Add some CA around the hole to harden it as that's going to have the strut in and out many times when you fit the upper wing to the fuselage.

Frames are as straight and matching as I can do! ha. Still a bit of sanding to remove excess plywood doubler. Should be sanded even with the balsa.

That's about it before going to standing the frames up and adding formers. And a reminder, the plywood sides goe to the inside of the fuselage. That gives a more even glue surface for the structures added such as firewall and other formers and platforms.
Current Build = 1/3 BUSA Fokker DVII

dlabby

Darrell Abby

Lane C.

Hi Darrell, the left/right frames need to be very straight to get a square and true fuselage. Going to reposition the plans so the top view is in the center of the build board. Right now it's almost all off to one side. Need to be able to put a square on both sides of the fuselage.
Current Build = 1/3 BUSA Fokker DVII

Lane C.

Got the frame glued up! Formers and cross braces added. Gas tank shelf added.
Current Build = 1/3 BUSA Fokker DVII

Lane C.

Added the gussets to the aft end cross braces. These are important so don't skip them. They add lots of support to prevent the fuselage from twisting. It was amazing how much more rigid the fuselage was after adding them. Also added the horz tail for looks to see how the extra positive incidence looks. I just keep trudging along!
Current Build = 1/3 BUSA Fokker DVII

Lane C.

March 12, 2021, 06:37:18 PM #39 Last Edit: March 13, 2021, 07:53:32 AM by Lane C.
Later today, I brought out the rudder and stab to fit to the horz stab. Changing the incidence of the horizontal changed the required shape of the stab as per the plans. The rudder fit the same, but had a gap under the counterbalance.

But, the fix was not difficult and I only needed one piece on the rudder and one on the stab. Easy.

First two pics show the gaps. Big one on top of the stab and smaller one the the aft.

Last 4 pics show the added balsa. Not hard at all, easier than I anticipated.

Parts still tack glued together. Will leave it till I get closer to attaching those parts to the fuselage.
Current Build = 1/3 BUSA Fokker DVII

Lane C.

At the tail end, the tail skid needed to be built up. Not a hard project but involved some metal work.

The skid had a spring that is attached to a beam on the aft end and the top of the skid. The photo tells the story.

Also added the gear support beams on the forward bottom fuselage. Added one more support beam for the D struts that hold the upper wing. The manual stops this part of the fuselage build and starts the third wing or subwing for the landing gear. BUSA suggests that it's easier to build that before the turtle back is added to the top of the fuselage. Seems to make sense.


Current Build = 1/3 BUSA Fokker DVII

Lane C.

On to the shock absorbing gear! This is a bit of metal assembly and soldering. The parts are mostly made, you have to trim them and put them together.

The main part of the gear is what they call the "spreader bar" which is a 19 inch long piece of basswood. On each end is a preformed metal bracket that bolts to the spreader bar and the shock absorbing system is soldered to that. Takes a few hours as you need to set it at the correct incidence angle prior to soldering. The incidence angle pertains to the sub wing that this assembly will bolt inside of. The sub wing build is next.

I failed to take pics at the very start, so, you can kinda get the feel by looking at the pics of the completed gear build.

The build starts with the fuselage inverted and the 2 main gear support struts secured to the heavy mounting blocks. The spreader bar has steel brackets that carry the bottom of the strut legs. Added to this are two 1/8 inch steel rods which are part of the bungee cord system. Once that is built up, you measure the incidence of the spreader bar based on the model sitting on its top (flat, level, 0 degree surface of the building table). The manual says to make the spreader bar -1 to -2 degrees. Which, when the plane is upright means that the leading edge of the sub wing is lower than the trailing edge, or negative incidence. Not sure why, but that's the way BUSA says to make it!

The two flat washers are there to hold the bungee cords on. The larger rod is the axle and the bungee cords are wrapped many times back and forth over the axle to provide a shock absorber effect on landing. The DVII will be 45 - 50 pounds, so, the plane needs some help on touchdown! Especially on the first few flights.

The 1/4 Scale DVII does not have any shock absorbing system, which is not recommended. I bought an after market kit that had a shock absorbing system for the 1/4 DVII.
Current Build = 1/3 BUSA Fokker DVII

Lane C.

Got the sub wing started yesterday. Not a big build and this piece is kinda fragile. So, likely will cover with glass cloth.

Wing is built in two parts - forward and aft so the landing gear can be inserted and removed if required.

Current Build = 1/3 BUSA Fokker DVII

Lane C.

I skipped forward to the LE being glued on the forward section with Yellow glue. Got a few pounds of weights on there to make sure it stays flat and true! Ha.

Took the weights off. Glue was dry.

Got out the Master Airscrew mini-plane and went to work shaving the excess balsa off to the shape of the top and bottom sheeting.

And last pic, drew the black line down the middle of the LE to tell me when to STOP. 3D shaping sander tool is on top of the sub wing. I've done about a minute's worth of shaping, then quit for the night. Will get back to that tomorrow.
Current Build = 1/3 BUSA Fokker DVII

Lane C.

Keep it going! Next session today I installed the gear spreader in the sub wing. Took a while, but not too bad.

But first I shaped the leading edge.

Then to making the cuts so the gear legs would fit the wing. Kinda rough at first. But then smoothed the cuts up.

Then put the gear assembly back on the fuselage to see how she looked. Not too bad!

Current Build = 1/3 BUSA Fokker DVII