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Jay Burkart's blog
Posted by Jay Burkart | Apr 29, 2011 @ 01:19 PM | 6,475 Views
I have finished covering and trimming out the Airborn 1600.
Still waiting on the motors.
The covering is Ultracote, mostly transparents.
The motors will be from NEU and have been on order since Feb 14th.
Going to try it with both LMR and Texaco motor setups.
I might use model in both events just by changing the motor.
Otherwise I may use my 1360 sq in Airborn for LMR and the 1600 for
the Texaco event.
I hope to do some photos outdoors whenever the rain and the wind stops
for a while.
Posted by Jay Burkart | Mar 26, 2011 @ 10:57 AM | 6,586 Views
I have completed all three of the Airborn 1600's to the ready to cover
stage.
Two of them are already on their way to new homes for this years SAM contests to be outfitted and covered by their new pilots.
I have started the process of covering mine and setting it up and
will continure documenting that in my blog.
Here are some pictures of the framed Airborns.
Thanks for bearing with me.
Jay Burkart
Posted by Jay Burkart | Mar 20, 2011 @ 11:44 PM | 7,456 Views
I cut and shaped the front window blocks, Quite a lot of balsa butchering to be had here.
That window block is massive.
Also the nose cowl blocks on the firewall motor mount is made for most of the models.
Piece of 1/2" balsa here and some 1/16 balsa strips around the edge of the motor mount themselves
to have them blend in with the sheeting of the fuselage and give the motor mount a balsa sheath
all the way around to make the covering adhere better.
Lastly bent up all the landing gears of 5/32 music wire, plan on heat treating all the gear
so that it toughens it up quite a bit and makes it not bend so easy now that the music
wire we get is about as soft as solder....Continue Reading
Posted by Jay Burkart | Mar 14, 2011 @ 09:34 PM | 8,267 Views
I have attached the tail sections to the fuselage. The vertical stab had been attached to the
horizontal stab previously. Now the horizontal stab and vertical are attached to the fuselage and
aligned. There is a cross platform of 1/4 plywood attached across the very rear of the fuse.
Then a piece of hard trailing edge stock is attached to the fuselage just in front of where the
horizontal stab rests on the fuselage. This is essentially a flat section built in to the fuselage
when framing the Trailing edge material is to anchor a alignment hold down tab of 1/16 plywood,
that protrudes from the leading edge of the horizontal stab at it's center section.
At the bottom of this TE material there is a place cut into it that is removeable to be able to
change the angle of attack of the stab if trimming is necessary. This is scored and close to
cut free but not removed so that the provision is there.
The stab is then aligned and the tab glued on, then the stab has two holed drilled through it
for 6-32 nylon bolts to bolt it to the cross platform. This is realinged to be square with the
center line of the fuselage and then drilled and tapped to accept the 6-32 bolts and the
thread hardened with thin CA and retapped.
I also put in ballast tubes right at the CG of the fuselage to be able to insert lead slugs to add
ballast to make the competition weight rules for the SAM events of Texaco and LMR.
the ballast is removeable as with the batteries we are...Continue Reading
Posted by Jay Burkart | Mar 05, 2011 @ 01:37 PM | 6,902 Views
I have been working with the stringers for the bottom side of the fuselage cowling.
After doing that part the fuselage has a bottom keel that runs about 3/4 the length of the fuse.
This also is the area where the landing gear exits and the bottom hatch is fitted into the fuselage.
The landing gear exit is relatively straight forward just a 5/32 gap between formers to allow the gear wire to exit and allow for pulling the gear out if needed. The hatch in the bottom is a bit more involved because of the flat bottom of the fuselage superstructure and then the angular keep shape over that. Also the fuselage bottom is on a curve at the point the hatch needs
to be place, then there is a hatch latch needed to release the hatch..
The hatch needs to be relatively long to allow to move the battery pack along it to allow for CG adjustments when motors are changed due to their difference in weight....Continue Reading
Posted by Jay Burkart | Feb 26, 2011 @ 07:58 PM | 7,129 Views
Got all the sides joined and started finishing the insides of the fuselages. Slide in Landing gear mounts, Wing Trailing edge wing mount reinforcements,
stringers for cowling.
All are mounted in all three. We are setting up with 5/32 landing gear wire as the
targeted flying weight will be 114 oz to use the 1900mah 3S lipos.
Probably 10 to 18 oz of ballast will be needed to make the weight rule.
I am guessing that the finished weight with all the gear will be around
100 oz for the LMR and 96 for the Texaco.
That will bring us close to the 10 oz/sq ft target....Continue Reading
Posted by Jay Burkart | Feb 23, 2011 @ 09:21 PM | 6,309 Views
I have made all the side pieces of the fuselages and have them ready to be joined
Also the wedge piece at the very tail of the fuselage is glued to one side before
joining the sides, it is a piece of 3/8" x 1.5" Trailing edge. The notch is to clear the rudder mounting
screw going up from the bottom the the stab and the other notch is the hardwood crossmount for
the horizontal stab itself. Also is shown how I sand the sides flat.
A Sanding T with the fuselage side pressed against a sanding board
with sandpaper attached to it.
Posted by Jay Burkart | Feb 08, 2011 @ 11:19 PM | 7,068 Views
I have been building fuselage sides for the last several days.
Cutting this lumber in this fuselage requires sawing each piece as a knife nor razor blade
can't cut through this lumber.
And there is a lot of cutting and fitting of all the longerons, uprights, gussets etc.
Right now I have 4 side completed and the 5th is on the board.
Six sides are needed for the 3 Airborns under construction.
With variance in wood sizes you can't really cut all the parts and just fit it together.
Each side is unique and has to be fit together.
I should have the side done and ready to sand in a day or two.
My Dremel saw and 12" sander are my best tools.
Also the pieces are so thick that you can't build one side on top of the other....Continue Reading
Posted by Jay Burkart | Feb 03, 2011 @ 07:18 PM | 7,654 Views
Finally got my saw and a start on the fuselages.
I have been making some of the cut pieces with exact angles and wing saddles
for the fuselages. A lot easier now that I have a small Dremel 4" saw.
The one picture is how I cut out the wing saddle so that the wing sits at
1.25 Degrees positive angle of attack, the stock Airborn is set at about 5 deg
which is way too much for RC flying and good thermaling characteristics.
I have proven this angle after now building 31 Airborns over the last 4 years.
I also have the Horizontal stab so that I can change it's angle if needed but
with settling on the 1.25 deg on the wing I haven't needed to trim the H Stab.
Posted by Jay Burkart | Jan 20, 2011 @ 07:29 PM | 6,694 Views
They are ready to cover.
What is left is installing the LE pins when mated to the fuselage
and the trailing edge wing bolts will be drilled to mate to the fuselage.
The ply reinforcement for these are installed at the center trailing edge.

The wings have a span of about 9 ft 5". Darn, I was trying for 10ft.
The Chord is about 16"
I can't even stand the darn things up in my shop.
You can hide behind these wings.
Hold them over your head in a breeze and you'll be airborn.
They look good if I do say so.
Now, hide all that pretty jointery under covering, how sinful.
I will start on the fuselages soon, still waiting on my new saw.
Posted by Jay Burkart | Jan 17, 2011 @ 06:46 PM | 7,286 Views
Having done the wing bisection the root panels need 1/16 Ply end cap ribs.
These are epoxied on and then sanded to conform exactly to the midsection sheeting.
Best tip on doing this is to put painters tape around the root of the wing section to
keep the epoxy from getting over on to the sheeting and also as a tell tale for when
sanding the cap rib to be flush with the sheeting.
Hold the tape about 1/16 back from the joint so that the epoxy does not glue the
tape in place, I also paint the epoxy on the ply rib with an acid brush that has
it's bristles shortened so that they are stiffer and can more effectivley brush out
the epoxy.
Next is the install of all the 1/16 ply dihedral braces on the Spars, Trailing edge
and leading edge.
There is a lot of cutting a fitting here and a pattern is cut from balsa first and then
traced onto the ply and all the braces are cut out. Make sure that the outer
ply grain is horizontal. A lot of even the aircraft ply now days is only 3 ply and
the two outer layers are in the same direction....Continue Reading
Posted by Jay Burkart | Jan 15, 2011 @ 09:02 PM | 6,880 Views
Cut all the midsections into two pieces right down the center line, through the joiner tubes
and into two equal parts with tubes perfectly aligned and ready for plywood end cap ribs.
One picture shows the cut through section with a 1/16 Ply end cap rib not the joiner tubes
showing through. A carbide blade cuts these tubes very well.
Then we cut the dihedral angle on all the the midsection tip ends and the matching
angle on all the wing tips. Nothing like a radial arm saw to do this with a nice 80 tooth
carbide blade for a slick cut. Also I made a little jig to align the tips for a square cut.
Just basically a wedge of 3/4" wood cut at the complementary angle of the tips
leading edge angle and trailing edge angle.
With all the dihedral angles cut on all the pieces we primed all the raw ends of the
parts like spars, Trailing edges and leading edges with thin CA.
Then I used my wing dihedral joining jig to match all the midsection halves to their
respective tips. Easy to line each wing panel up and joined.
Next will be the dihedral braces and ribs at the joints, also epoxy on the end cap ribs....Continue Reading
Posted by Jay Burkart | Jan 13, 2011 @ 09:36 PM | 6,840 Views
A bit more progress on the Wings.
The center or midsection of the wing has to be prepared to cut it into two right in the middle
to make two sections that will plug together.
So the wing has to be esentially covering ready through the entire middle section and then
it is cut into two halves on a radial arm saw.
This will mean cutting all of the structure including the joiner tubes.
Also in the middle section the TE is prepped for where the mounting bolts are installed
very near the TE a little bit off the center line.
Also you see the locating holes at the LE for the CF pins.
These go into the ply reinforced ribs on eithes side of the center.
I hope to be cutting the wings in two in a couple of days.
Then the tips will be joined onto their respective half of middlesection.
Doing the joined wing this way allows for quicker build and also the two
sections will exactly mate as they were built as one and then cut down the middle so both sides will match....Continue Reading
Posted by Jay Burkart | Jan 03, 2011 @ 10:14 PM | 5,767 Views
Made a bit more progress on the 1600's
Got one set of the tips rough framed and the other 2 sets should be easy.
Nothing special on these, just have to take in account that I build the wing joint from the midsection to the tips different than in Jim O'Reilly plans.
Since I do not use plug in tips like are on the plans.
Jay
Posted by Jay Burkart | Jan 01, 2011 @ 08:19 PM | 5,773 Views
I have framed up all three midsection wing panels.
This is the shear webs on the midsection with 1/16 balsa vertical grained on the outer 6 panels and
1/16 Plywood with the outer Plys in vertical grain for the inner panels.
Also the locating pin tube socket for the center section joiner.
This is toward the TE of the wing and is a tube that accepts a 1/8" music wire pin.
Note the sandwich of three ribs for the center section. The middle ribs is 1/8" to allow for
the kerf of the saw blade when I cut the center section in two parts later on.
Posted by Jay Burkart | Dec 28, 2010 @ 11:31 PM | 5,319 Views
This is the framing of the midsection of the Airborn 1600 Wing.
This has the wing joining system and alignment pin.
The framing has a kerf spacer right in the middle to allow for the width of the
blade when I cut the wing in two with a radial arm saw.
Note the end plugs installed on the joiner tube in one step so that the joiner
Carbon fiber rod does not just push all the way through the joiner tube.
The tube is installed at this time without the Carbon Fiber rod so as not
to cut it in two when cutting the wing section.
Posted by Jay Burkart | Dec 27, 2010 @ 05:28 PM | 4,179 Views
Made a little more progress on the Airborn 1600's.
I made the fastening system between the Horizontal stab and the Vertical stab.
I have done this fastening system for quite a few years now and have not had any problems.
Used a 1/8" carbon pins in the front bottom corner of the Vertical Stab where it goes into
a socket at the middle of the Horizontal stab. The Horizontal stab on this model has a 1/16 plywood
bottom at the bottomed of the slot to give it some extra strength and a seat to where the
rear 8-32 nylon screw pull the rear of the Vertical stab down and in.
The carbon fiber pin goes through a piece of hard balsa and the H. stab leading edge which
are also hardened with thin CA. The CF pin goes about 1" up and into the V. stab and is held
in with thin CA also. The thin CA will wick up and around the pin all the way and really holds
very tight, better than an epoxy joint.
Posted by Jay Burkart | Dec 22, 2010 @ 09:08 PM | 3,979 Views
This is still prep work for building the wings.
Two of the center section ribs, one on either side of the CL are doubled with 1/8 aircraft plywood
to reinforce them for the wing mounting pins of 3/16 carbon fiber that will stick out the leading
edges into a bulkhead on the fuselage.
So you see the 1/8 ply sub ribs. Also the spars are doubled at the center section
to make the wide enough to support the 3/8 OD brass tube that is the socket for the
Carbon Fiber joiner tube. The spars will support Plywood shear webbing in support on
either side of the brass tubes as the joiner tube "box".
Also the joiner brass tube is shown how it is roughed up for very good adherence to
the epoxy that will be used to join the box sides together.
Also you see the joiner tube with the holes drilled for it through the center
section ribs giving it's location between the main spars. This is just given
as an idea of how it will go into the ribs.