I have started to build a Brodak 1/2A Pathfinder.  The kit seem to have good wood.  The only wood missing is the sticks required to do the fuselage and tail feather cutouts.  I did have a few minor problems figuring out how to do certain things.

The first was figuring out where to place the leveling stick that goes under the trailing edge of the ribs. The problem is that the pictures in the instruction book are faded and it is hard to see detail. It soon became obvious that the leveling strip went along the inboard edge of the trailing edge sheeting.  This caused the spar to be at right angle to the building board.  Speaking of the spar, when gluing on the plywood doubler place scrap piece form the wing ribs in several of the wing slots to make sure the notches are aligned.

The next problem was the cutting in half of the short ribs.  I cut them exactly in half. It is best to leave a little of the v notch on the top half of the rib.  This way it is easier to align the rib on the leading edge. Also it is necessary to keep the two halves of  each rib together.  That way they glue back together straight and true.  As you can see in the picture I laid them out on the plans as I cut then in half.

The line slider and wing tips were a little vague.  The 4-40 hardware that came with the slider seemed a little large.  I replaces it with 2-56 hardware.  I made a nut plate from a piece of tin stock with a 2-56 nut soldered to it.  The wing tip that holds the slider has it's center section removed to allow the lead-outs to pass through.  Before installing the wing tip I only cut out about a 75% gap.  Per the plans I then cut the notches for mounting the slider and glued the slider in place.  I then glued the wing tinp in place making certain it was centered.  After the last of the win tip ribs were installed I removed the reaming 25% of the gap. This assured the wing tip held is shape while being installed.

I built a sanding jig to taper the ailerons.  The strip of plywood glued to the base is the same thickness as the un-sanded ailerons.  I mark two sand-to lines on the to-be-thinned part of the ailerons.  The masking tape on the sanding block slides along plywood strip.  When sanding I check often to make sure I am sanding straight and am sanding to the sanding line.  Of course you flip the aileron to remove equal amounts from both sides.  I did not do the cut-out option of the inboard aileron.

The bell crank, aileron hinging, and aileron tips were all per the instructions and plans.  The out board aileron tip is mounted with the provided sheet metal tabs allowing it to be used as a trim tab.

So the wing is ready for it's final sanding and covering.  Next I will build the tail feathers.  I will do the lighting cut-outs and add the stick bracing on these parts.  I prefer a noise heave aircraft to a tail heavy one.  It takes a lot less weight in the tail to achieve the correct CG

The last of the wing pictures

Great job, Thanks!

What power system are you going to use? Nitro? Electric?

I have on hand a NV AMD 061.  I plan to run it on a balloon tank.

John,
I have hundreds of flights on Pathfinder/Norvel Big Mig .061's combos.
Be interested in the performance w/ the AMD as I have two in the drawer.

Roger V.

What size tank and is it set up as a uniflow?  I have had good luck with balloon tanks but they require replacing the balloon.  A hard tank would be nice if it works well. 

Tail feathers are ready for shaping and final sanding.  I make cutout templates by copying the plans and use a glue stick to attach plan to part.  I then use a jig saw to cut out the center chunk.

 It's my understanding that the Big Mig is more of a low rpm, bigger prop (relatively) than the AME, which is more of a high rev engine.
If that is correct, you have the better of the two for stunt.
R,
Chris

By the way looking at the picture below if I ever build another 1/2A pathfinder I would not cut the short ribs in half.  I would load then onto the spar before I installed the leading edge.  I would not glue them at this time.  When installing the leading edge I would glue the full ribs first and then square up and glue the short ribs last.  Should take less glue and save a little weight.  It would definitely be faster.

Chris,
Agree, off to club annual picnic and some flying before it gets toooo hot! Will add more info re my config. tonight.


John,
Sorry I hijacked your "build thread".

Roger

Great picnic, good food, lots of flying!
My Big Mig .061's use a Galbreth (sp) head, two Norvel head shims, Nelson plug, APC 6x2 prop. Have never seen a need to go above 15% Nitro, power is more than adequate.Engines tach over 24000 on the ground and, if i remember correctly, run at ~26750 in the air (we have access to an audio tach). Lap time w/ 48' x .008 lines is 3.9 - 4.0 seconds..
 

Did the cutout on the fuselage.  Next step is to add plywood doubters and motor mounts.  I have a question.  Is the cowling and spinner ring add anything but good looks?  To save weight I plan to omit them.  Also it permits me to use lock nuts instead of blind nuts for mounting the motor.   

John,
The .080" wire provided in kit will flex without a support.
I have used .10" OD  threaded one end, P'rod wire without flex support, never a problem. Clevis's both ends, one threaded/one slip fit JB welded on final assy. after flap/elev locked at 0 - 0 .
With the "current"  old pic posting problems, dont want to over load Sparky's repair tasks so sending my P'rod pic to your e-mail.

Roger

its starting to look like a PATHFINDER.  I am covering the pieces separately.  Pictured is the start of a dry fit. As always, my finishes are 10 ft view-able only.   

Might be better in wind at 12 oz?
What is the wing area??
Looking like maiden flight is drawing near, "YAY"!

R,
Chris

I'm going to run the same mill on my 1/2A Baby Stuka...I think the wing area is similar, might be a bit larger in fact.

I think I will need a 1-1/4oz uni-flow tank to be safe to fly a full pattern.
What size tank will you use? Balloon, muffler pressure, or uni-flow?

I was hoping for 11 oz.  Looks like it will be around 12 oz.  Should still be a good flyer.

John,
We have one in our club, never weighed , but i am sure it is 12 +++ oz. Yes, it is a good flyer!!!!   

Roger V.

I like the transparency.  Beautiful construction.

I wounder what is the difference between the AMD and the AME. 

I believe none. I think one is Cyrillic alphabet and one is the English translation.

Speaking of mufflers I don't have one for this engine.  NV sells one for this engine.  Would I really want to run a muffler on a 1/2A?

Many fields require it. They work well plus you can tap the muffler pressure if you desire.

George

3 more pictures.

Depending on where the elevator horn is set, you may have more flap throw than elevator. Consider moving the bellcrank to flap clevis down and the elevator drive clevis up.

Otherwise, it is gorgeous!!! 

My electric version weighs about 14 ounces and does a very clean pattern. I think you will be very happy with this model!

Depending on where the elevator horn is set, you may have more flap throw than elevator. Consider moving the bellcrank to flap clevis down and the elevator drive clevis up.

Otherwise, it is gorgeous!!! 

My electric version weighs about 14 ounces and does a very clean pattern. I think you will be very happy with this model!

Larry, Would you be kind enough to share your motor / esc / lipo setup?

Depending on where the elevator horn is set, you may have more flap throw than elevator. Consider moving the bellcrank to flap clevis down and the elevator drive clevis up.

I checked the elevator to flap throw.  The flap horn is long and the elevator horn is short.  It appears that I have around a 2:1 ratio between the two with the elevator moving the most.  The controls are all set per the Brodak blueprint and instruction book.

Hi John,

Beautiful airplane!

Hard to tell, but it looks to me like the vent tube bends on your tank are nearly collapsed? Could they be limiting the air flow into the tank?

If you want to try muffler pressure I'll look in my tank stash to see if I have one with a pressure nipple. If I have one you can have it as I don't use mufflers on my Norvels. If you want to try pressure, send me your mail address by PM, or email it to the email address listed in my user profile.

Bill

Thanks for the offer.  Let me try the balloon tank set up first.       I had a weird thought.  I have a balloon on the inside of a standard tank.  I bet muffler presser would work.  Vent the presser between the tank and the balloon.  The presser would squeeze the balloon.

John,
Was it determined that the engine is an AME? If so, it does need pressure. i had a similar setup on a 1/2 A LL Stiletto and it would not run properly. changed to a bladder, problem solved. My Big Mig .061's will draw fuel from the 2 oz cylindrical tank.

Well I finally got an acceptable engine run from my NV 061.  The balloon tank didn't work all that well so I went to a bladder tank.  Starting a bladder tank setup is a bit of a pain, especially if you are alone.  It takes 3 hands, one to hold the airplane, one to hold the starter motor and one to release the fuel clamp. To solve this problem I made a tie down board to hold the airplane.  Once I got it set up and running I had rock steady RPMs till the last drop.  The bladder is inside a 4 oz Sulivan tank.  This is bigger than is necessary but it is what I had on hand and I needed the noise weight for proper CG.  I did have one bladder explode.  Being inside a tank contained the mess.   

                A very easy solution to your bladder is to provide a alligator clip mounted on your fuse directly in front of your tank. You can grind off the teeth, place the tubing in the jaws of the clip to retain the fuel in the bladder. You can now hold and flip operating the clip with your thumb on the same hand. A pinch off can be made with a simple piece of music wire as well mounted to the fuse, slide the fuel line in between, when the engine is running, flip the fuel line out of the pinch off

Are you using the stock needle valve with the bladder?

Yes but is is vert touchey.  I may research a fine thread needle.   Any suggestions?

John,I purchased my fine thread NVA's from Doug Galbraeth years ago. Just checked,  They are not on his web site for Norvels right now, but.......  Suggest you contact him.

Tel:  530-400-3562     Web site:  F*1*C*do*ug@aol.com  <-- remove *'s before using.

fyi, his Norvel heads and Nelson plugs are also recommended. If you purchase same, use two head shims w/15%N for more than adequate performance
 

Roger Vizioli

I checked with Doug.  He does not have a NVA that fits the NV 061.  He can supply a Nelson plug because it is the same as a COX.  Texas Timers has a NVA that would work however it is JB welded in place.  SO I think , for now, I will stay with the stock NVA.  I am getting consistent runs with it.  You just have to understand that a 1/4 turn covers the set range.  

              John, depending on which venturi is supplied to that .061, you can use the Texas Timer assembly or find yourself a Cox (red) postage stamp backplate and press out that assembly. The Cox needles are the brass needle with no knob with the black friction sleeve. These are the 128 TPI just like the Texas Timer version. Cut a piece of 5/32 tubing the same width of the venturi even a tad smaller in width and file a hole in the center. This hole is where the hole in the spraybar lines up. The 5/32 tubing is just a sleeve. The tubing can be soldered to the spraybar. Just clean and flux the perimeter this way no solder wicks into the hole in the spraybar. Sometimes the sleeved assembly is rather a tight fit, if not, a touch of JB weld works real well. JB weld can easily be cleaned off using standard rubbing alcohol. If you know anyone who has a Larry Driskill needle, these were a direct replacement and bolt right in.

Cool deal, John.
Hope your next flight report comes soon.

Very nice rig you got there.

Tell your friend that is a great picture, John.

R,
Chris