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Dirty Birdy Instructions Update

Old 02-20-2010, 03:46 PM
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dbacque
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Default Dirty Birdy Instructions Update

The Dirty Birdy is one of my favorite airplanes but the instructions can be a bit confusing at times. I just completed building my second Bluejay Dirty Birdy .60 and instead of doing a build thread, I decided to keep detailed notes and generate a set of instruction updates. These notes are a combination of instruction corrections and clarifications along with notes on how I did things and some general ramblings.

I've attached a PDF of the notes and I'll paste them into posts for those who prefer to just read it here.

There are pictures of the finished plane as well as some shots of particular details.

Before anyone asks, the nice circle in the center of the wing in the Wing Hold Down and Wing Filler pictures was where I cut the servo wire exit on the wrong side of the wing. [sm=red_smile.gif]

If you find these notes useful or have suggested updates, please let me know. If you would like these instructions in Word format, drop me a line and I'll e-mail them to you along with full resolution pictures.

Dave
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Old 02-20-2010, 03:48 PM
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dbacque
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Default RE: Dirty Birdy Instructions Update

DIRTY BIRDY “60”

Joe Bridi’s Dirty Birdy is one of my favorite planes. There have been numerous discussions of problems with the instructions so I thought that while I built a replacement for the one that I killed last year it would be a good time to keep some notes and post a few corrections. Let me start out by saying that this is not a difficult plane to build. If you’ve built a few planes the Dirty Birdy shouldn’t present any real challenges. However due to a few errors and some changes to the kit through the years, the instructions can be somewhat confusing. I hope that these instruction updates will help eliminate some of this confusion

Let me say that I am not now nor have I ever been associated with Joe Bridi or Bluejay Models. These instructions are just my take on building this plane. If you don’t understand something that I say and if you’re cool with the instructions as they are, by all means follow the original or do things the way you think best. Additional insight into the evolution of this plane and the plans can be gained from looking at the original construction article http://www.trentonrcflyers.com/patte...rdyArticle.pdf .


A few general construction notes:

This plane has lots of shaping to be done. In many places the instructions tell you to sand to shape. A razor plane gives much better control, shapes faster and makes less mess. If you don’t have one, go buy one right now and practice with it. I use the Master Airscrew razor plane but any one will do.

When you need to shape a block next to sheeting (LE, wing tip, etc.) protect the sheeting with blue painters tape. Now you can carve away without damaging the sheeting. Carve flush with the sheeting first, don’t try to round it right away. When you start tearing the tape you’re getting close, treat that area with caution. Once you’re just about flush with the entire surface, then you can start rounding. But go slowly, it’s easy to get too aggressive and leave a flat spot. Only use the razor plane to get close. Then switch to a sanding block to even things up and finish shaping. Leave the tape on even for the early sanding. Finally remove the tape and finish sand. If you’re really tearing the tape up, it’s doing it’s job and you’ve saved your finish. Remove the tape and apply a new piece.

When you’re carving something long like a leading edge or an aileron bevel, use long strokes, each one the full length of the part. This will help keep the shape constant.

I do lots of filleting with microballoons and epoxy. The trick of protecting the wood with tape while sanding works great around fillets too. It keeps you from cutting into the wood. You can see some of my microballoon filleting in the pictures of the Wing Filler and the Tail and Hatch.


A few things need to be taken care of before starting assembly. The original kit had pre-cut stab slots in the fuselage sides. But the current fuse sides do not have the slots pre cut and the instructions don’t tell you to cut them. You will do well to mark and cut them now and it’s much easier to do before the fuse is assembled. I use tracing paper to trace the outline of the aft end of the fuse sides and the slot from the plans. To cut both slots exactly the same I use a little Scotch double stick tape to hold the two fuse sides together, then double stick tape the tracing in place. Then it’s an easy job on the band saw to make the slot. Or each fuse side could be marked and cut by hand with an X-Acto knife.

The fin slot in the fuselage top is also no longer pre-cut but I find it more accurate to cut this slot after the fuselage is framed and squared.

Be sure to make the cutouts shown on bulkheads #2 and #3. Again, the instructions make no mention of this. I think these cutouts may have been precut in an earlier version of the kit.

You also need to determine if you need to move the firewall position based on your engine selection. These planes tend to come out nose heavy so moving the firewall back a little is not a problem. Determine the required distance from the firewall to the spinner based on your motor mount/engine/spinner combination and if necessary mark the new position on the plans.

Another thing you need to start considering is wing incidence. A note on the instructions says the wing should have 1/64” positive incidence which works out to 0.068 degrees. The instructions say you should have 1/32” positive incidence (0.137 degrees). But if you measure the plans it actually shows 7/32” positive incidence, right about 1 degree positive. And the parts exactly match this. I don’t know which is right. The instructions will have you adjust the incidence when you mount the wing but it’s difficult to make large adjustments once everything is done so it’s best to decide now what you want. On my first Dirty Birdy I shot for the 1/64” positive incidence but wound up with 1/32”. This plane needed significant up elevator trim to fly level. My second plane I went with the stock 7/32” incidence which gives you just about one degree of positive incidence, many people consider this to be ideal. With one degree incidence the second plane required four clicks down trim, about 1/16”. And this will increase as I move the CG aft. Of course both planes flew fine.

So which incidence was the original design and which was the update? I don’t know. You’ll have to decide for yourself which number to use. Having tried both I think the best answer is somewhere in between but who knows what other things affected the trim on my two planes.

Whatever incidence you choose, adjust the wing saddle now or step 14 will be a major headache. Read step 14 of Completing the Wing to determine how the incidence is set, you’re just going to measure the front and back of the saddle to the top of the fuse side. Remember to include the shape and thickness of the leading and trailing edges. Trace the wing saddle and adjust the saddle to your desired angle before you start building. You’ll be way ahead.
Old 02-20-2010, 03:49 PM
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Default RE: Dirty Birdy Instructions Update

From here on the notes are numbered to correspond to the step in the instructions under discussion. In some cases they are just notes on the step. In other cases they are a complete rewrite of the step. Please be sure to review the original instructions along with these notes.

2. I don’t understand the last sentence of this step. The doubler is not 1/4” short of the bottom and it does not touch the 1/4” triangular stringer. Don’t worry, just ignore this and glue the doubler in place. Be careful in the placement of the doublers as they will guide the placement of bulkheads #2 and #3 in the next step. Accurate placement of bulkhead #2 is very important.

3. Make sure you have cut all necessary holes in the bulkheads. On bulkhead #2, I prefer to wait to drill the wing dowel holes until step 8 of Completing The Wing so they match exactly with the leading edge.

I draw the centerline on both the front and back of Bulkhead #2.

Paragraph 2, draw the center line down the length of all three top blocks. Draw a line across the fuel tank compartment top block at the location of the aft end of the engine compartment top block. Draw a line across the top block at the location of the cross brace in the servo compartment, at bulkhead #3 and at the location of the cross brace to the rear of bulkhead.

Paragraph 3, I do not find the lines on the fuselage sides to mark the location of bulkheads #2 and #3 to be necessary as the bulkheads fit flush against the doubler.

The last paragraph of step 3 is a common source of confusion. The top block cross braces are no longer factory cut to size. They are now provided as 1/4" x 3/8” x 24” balsa stock. I did not cut these at this point and I didn’t mark them at all. They will be cut to fit in later steps.

4. I find fitting an engine to a built fuselage and then drilling motor mount holes accurately to be difficult and prefer to prepare the firewall for the engine mount before assembly. So in step 4 I drilled the holes listed but I also drilled the holes for the engine mount blind nuts and mounted the blind nuts in the firewall.

5. The second paragraph should read Relieve the 3/8” balsa engine compartment as necessary for your fuel tank. See the plans.

The last line should read Use the line you drew across the fuel tank compartment top block earlier to locate the engine compartment top block.

6. Due to the cross braces not being pre-cut, I find it easier to get them sized accurately and mounted later. I skip this step and install these pieces at the end of step 7.

7. The 3/8” triangle stringers used in this step are not standard triangle stock. They are triangle stock with one corner cut off. As stated in the instructions, the stringers should be glued to the fuse sides with the cut off edge uppermost.

Now is when I cut and fit the fuselage top cross braces from the 1/4” x 3/8” stock. One where marked in the area of the servo compartment, one where in the position of bulkhead #3 (the bulkhead will be glued on top of the cross brace) and one aft of bulkhead #3.

10. The vertical support braces in this step are also cut from the 1/4” x 3/8” stock.

12. The plans show the 1/4” triangle stock on the front of bulkhead #2, not the back.

15. The balsa triangle stock is actually 1/2” x 1/2", not 5/8”. On my first Dirty Birdy I had a problem when gluing these pieces to the top block. This time I cut the pieces to fit but installed bulkhead 1 before installing the triangles. I believe it was much more accurate.

17. The instructions say to use a square to make an alignment template for bulkhead #1 but the bulkhead needs to be angled for 2 degrees down thrust. So you actually need a 92 degree template, not a 90 degree template. Using a protractor, mark a 92 degree line across a sheet of 1/8” balsa. Mark this corner on the template so you can distinguish it later. Cut the template with an X-Acto and a straight edge.

18. If you waited to install the triangle stock as I did, use care when you epoxy bulkhead # 1 to the fuel tank compartment block. Make sure you do not ooze glue into the area where the triangle stock will go.

19. At this point I epoxy in the triangle stock as well as pulling in the sides and gluing them to bulkhead #1 and the top block.

20. These parts have changed. There aren’t really any fuel tank compartment side blocks with notches cut into them. They are roughly triangular pieces made from 3/16” sheet. Check the parts list. If you have moved bulkhead #1 from the location shown in the plans, you will need to trim these parts accordingly.

Add triangle stock to the back of Bulkhead #1

Add triangle stock to the bottom of the tank compartment bottom sides.

22. The nose gear bearing is now integral to the engine mount. Install the engine mount. At this point I discovered that with my engine, the provided adjustable motor mount would not fit in the engine compartment, it was a little to wide at the front end. So I narrowed the front of the mount on a disk sander to the same width as the engine’s mounting lugs. It was now a perfect fit.
Old 02-20-2010, 03:50 PM
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Default RE: Dirty Birdy Instructions Update

23. If you have moved bulkhead #1 back, you will have to trim the fuel tank compartment bottom block to length.

24. I skipped this as I already had the blind nuts in bulkhead #1.

25. I removed the carb from the engine to make doing this cutout easier.

After getting the cutout done and the engine installed, I removed them all and fuel proofed bulkhead #1 and the fuse sides in the engine compartment where nothing is going to be glued on. I put Vaseline in the pushrod tubes and blind nuts to keep the resin out.

26. I skip this step until later.

27. The plans show these pieces as blocks. These parts are now triangle stock as stated in the instructions. I cut them back to butt up against the nose block instead of cutting angles on the nose block. Don’t get too obsessive about all these blocks, just build up something that you can carve away. You’ll carve and grind most of it down anyway.

Then I did the balsa chin block from step 26. If you moved bulkhead #1, you may need to lengthen this piece. Make cutout for nose wheel gear and relieve the interior floor for the nose wheel steering arm. Then glue chin block in place making sure to pull the sides back in to a width of 2 3/8” as in step 19.

28. The spinner block provided in my kit was a bit undersized. I was just going to add a little sheet stock to it but I cut it wrong when fitting it between the sides so I wound up making a new, larger block.

29. At this point I fit the engine without the carburetor or the muffler. You just want to be able to mark the spinner ring location. I think completing the fit around muffler, carb and needle valve is easier after the nose is shaped. I also think that shaping the nose is easier without the ply spinner ring. So once you’ve got the engine mounted, mount the spinner and determine if you need to trim the nose block or sides back. Once you’re happy with the nose block, mark the location of the spinner ring on the front and round the nose down with a razor plane to the marked nose ring location. Then mount the nose ring as described. I rounded the nose before mounting the nose ring as on my first Dirty Birdy I split the nose ring while carving the fuse down. Final shaping of the nose will be done later when the rest of the fuse is shaped.

Don’t be tempted to carve the fuse to shape yet. You can use a razor plane and then a sanding block to bring the top and bottom blocks down even with the sides making everything nice and square but don’t round anything at this point.


Stab, Elevator, Rudder and Fin

There is an error on the drawing of the stab. The right stab half is 1/8” shorter than the left. This bit me on both of my Dirty Birdies. Doesn’t sound like much but it’s easy to fix so just mark one side of the plans to match the other side.

4. Check the ribs closely to determine the front. Stack each pair of ribs and switch one end for end to figure out which end is which. Mark the ribs!

7. First sentence should be: Add the 1/16” x 3” x 12 1/2” balsa TOP SHEETING.

8. Before sheeting the stab bottom, add hinge glue blocks if desired.

9. I remove stab from building board and razor plane LE and TE flush with sheeting before adding tips. Protect sheeting from razor plane with blue masking tape.

10. I did this step after step 11

11. Don’t sand to shape!!! Nothing beats carving with a razor plane.
Old 02-20-2010, 03:51 PM
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Default RE: Dirty Birdy Instructions Update

The Wing Panels

Paragraph 3 of the wing panel instructions describe drawing lines on the ribs. This doesn’t work with the current ribs as they have notches in the front and aft ends. More on how I used these notches later.

Paragraph 4 of the wing instructions says that ribs #3 and #4 are notched but that is no longer the case so be sure to notch them for your desired gear position. Note that on the plans the notches are not as deep as the landing gear block. The block actually stands above the ribs by the thickness of the sheeting so the block winds up flush with the sheeting. On my first DB, I made a mistake and cut the notches to make the block flush with the rib so I just sheeted over it. I wound up liking this much better because I’ve always had trouble fitting the sheeting neatly around the blocks. Of course if you sheet over the blocks, you’ll have to carve away the sheeting where the LG straps go so they don’t crush the sheeting. To do this neatly, drill and install the gear straps. Then use an X-acto to cut the sheeting around the straps. Remove the straps and cleanly remove the little half moons of sheeting. If needed, add a little patch on the inside. When you cover, just MonoKote right over the depression and ignore it. When you mount the straps they will pull in and everything will be very neat.

I like my planes a little tail heavy and my first DB liked to sit on its tail when the tank was empty so I moved my gear back about 1/4" on this one. If you plan to use individual aileron servos in the wing panels, plan their location and provide holes through the ribs for the servo wires.

I understand the wing ribs in the newer kits have holes for a wing jig. I didn’t have the newer kit and I don’t have a wing jig. The instructions detail how to build the wing without a jig but I decided to build a jig on my building board. My jig consisted of balsa strips that fit in the slots in the front and back of the ribs and blocks to hold the strips off the building board. The jig was more work but was very solid and accurate. These instructions are for my method of building the wing. If you don’t want to build the jig, just follow the original instructions. But be sure to read the original instructions if you follow my method too. The steps marked with an asterisk are applicable to both methods.

To make the jig, cut four 3/8” strips from hard 1/16” balsa. Make these at least 1” longer than the wing, you want them to extend beyond the outside ribs. Make a pile of 26 - 1” x 1” x 1/2" blocks from 1” x 1” balsa. Pin the balsa blocks to the plans between the ribs about 1/8” inside the position of the leading and trailing edges plus one just outside of the first and last rib. Make sure the blocks do not touch the line on the plans for the LE or the TE or they will block the LE and TE. Look closely at the included picture. I build on a very flat hollow core door and hammered the T pins into the table. It was lots of trouble and lots of bent pins but it worked very well. The picture of the jig, spars and ribs tells the story. Note that this picture is before the LE and TE are added.

1. Pin the root end of the spar to the plans. Pin a couple of balsa blocks on either side of the spar in the outermost rib bay but don’t pin the spar itself, just capture it in place so you can lift the tip of the spar while the blocks keep it lined up with the plans. Again, look closely at the picture

2. Put the ribs in place on the bottom spar. Be sure ribs 3 and 4 have the LG notches down. (On the second wing panel ribs 3 and 4 must have the notches up.)

Slide the strip of hard 1/16” balsa into the front and back slots of the ribs, lifting the ribs so the strips will sit on top of the 1” blocks. These strips are only for positioning the height of the wing, they do not need to be glued to the LE or TE so seat them deeply into the slots. Make sure the strip extends beyond both end ribs to sit on the jig blocks on the outside of the first and last ribs.

Pin the hard balsa strips to the jig blocks. Make sure the strips do not extend beyond the front or the back of the ribs. Check the position of the ribs and square them to the table.

Add the top spar and be sure to set the spars completely into their notches. Realign the ribs. This is where the picture was taken.

CA the ribs to the spars making sure the spars are fully seated in the notches. Do not glue rib 1 to the spars! Use a square to line up the front and back of the ribs and tack glue them to the hard balsa strips. Do not get glue on the jig blocks.

3. Add the trailing edge. Glue only to the ribs, not to the hard balsa strips. Doing so will risk gluing the wing to the jig blocks

4. I shape the TE later

5. I do the sheeting later

6. I did the top spar earlier

7. Add the leading edge. I had one LE that was warped but since the ribs were jigged into their proper position I just glued the LE on making sure that it covered the tips of the ribs, not worrying if it was centered on the ribs. This problem was then fixed when the LE was trimmed in the next step.

*8. Very carefully use a razor plane to shape the top of the trailing edge to the wing contour. Don’t go too far and don’t damage the ribs. Finish this job with the long sanding block. I use a piece of paper between the sandpaper and the ribs to prevent damaging the ribs. Tape works well too

Again, carefully use a razor plane to shape the top of the leading edge to the wing contour. Be careful not to damage the rib profiles and finish with the sanding block.

On the second wing panel, after this step I removed the wing from the jig, flipped it over and remounted it to the jig. I only had to move a couple of the blocks to make things fit. Then repeat step 8, shaping the LE and TE. Flipping the wing allowed it to fit the jig better while shaping the LE and TE and sheeting the top.

9. Remove all the pins holding the aft hard balsa strip to the blocks except for the pins that are outside of the end ribs. Lay something down on top of the structure to weight it down onto the jig blocks. Add the 3/32” x 2” TRAILING EDGE SHEETING. Do not glue the sheeting to rib #1. . Put a few pins through the sheeting, the hard balsa strip and into the jig blocks to hold everything in alignment with the jig.

Remove all the pins holding the forward hard balsa strip to the jig blocks except for the pins that are outside of the end ribs. Make sure the wing is weighted down to the jig blocks. Add the 3/32” x 4” balsa TOP LEADING EDGE SHEETING. Do not glue the sheeting to rib #1.

Now we’re back in sync. Follow the original instructions with the following notes.

*12. Remember to set the LG blocks 3/32” higher than the rib surface if you’re building per the plans.

If you’re going to sheet over the LG blocks as I did, the blocks will be flush with the ribs, so you’ll have to cut the notch in the PLY PLATES 3/32” deeper.

17. When I turned the wing over, I was able to use the jig blocks again.

*Add hinge glue blocks. Cut the hard balsa strip away as necessary.

*19. Do not glue bottom TRAILING EDGE SHEETING to rib #1. Do not add bottom cap strips now. They will be done after the bottom leading edge sheeting is applied.
Old 02-20-2010, 03:52 PM
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Default RE: Dirty Birdy Instructions Update


Completing the Wing

1. Step 3 (trimming LE, spars and sheeting flush with root rib) must be done in order to set the angle of the root rib. Trim them close and then sand a little at a time, checking the angle frequently.

5 & 6. I built mine with a servos in the wing. If you choose to do this, steps 5 and 6 become: Cut Center Section Trailing Edge pieces to size. Align & glue.

8. If you haven’t already drilled Bulkhead #2 for the wing dowels, draw a center line on the LE.

13. For paragraph 2 of this step, I covered this area of the wing with Scotch Tape and tack glued the Wing Fillet Base Pieces on.

15. At the end of this step, do not remove the wing yet. If you do, the Wing Fillet Base Pieces may pull up a little leaving a gap between wing and fillet.

16. When you glue the back of the fillet base pieces to the fuse sides, do not pull them in to meet the fuse! If you do, the fillet will want to pull away from the wing at the outside edge. Instead, use triangle stock as a glue block and then add a piece of wood to fill the gap. None of this matters, it’s all going to be filleted anyway.

If you have waited to drill Bulkhead #2, make a mark on the fuselage sides right at the centerline of the leading edge

Now remove the wing.

If you have waited to drill Bulkhead #2, draw a line across the bulkhead connecting the two marks you just made. Now drill the bulkhead and the holes will be exactly aligned with the LE of the wing.

21. If you set the Landing Gear Blocks flush with the ribs as I did, you will not have to cut out the sheeting to go around the blocks. But after mounting the sheeting you will need to make a slot through the sheeting in line with the slot in the block. You can find the correct location by sticking a pin through from the inside on each side of the block. The slot will be right between the pin holes.

Add Bottom Cap Strips. If you are building servo bays in the wing panels, you may want to omit two cap strips on each side to allow for your servo mounting.

22. Use the razor plane to rough shape the leading edge. Then use the sanding block. Tape off the sheeting to protect it

Before adding the Tip Blocks, I install the ailerons to help guide in shaping the tip. Do not bevel the ailerons yet! Just hinge them and mount in place. Make sure they’re aligned with the inboard trailing edge.

Add the Tip Blocks. Carve tips flush with wing using razor plane (cover sheeting with blue painters tape first). Get tip close to shape of airfoil, then sand everything flush. Mark center line around outside of tip block. Now carve everything to shape.

Since I’m nuts, at this point I cut a 1/2” wide strip of 1/16” balsa and used the razor plane to carve it down to triangle stock. I used this as a fillet around the 1/16” Ply Wing Hold Down Plate. Or you can just fill this area later as the plans call for. These fillet pieces are visible in the picture of the wing hold down plate.

26. The Wing Fairing Front & Sides are 2 pieces of 1/4” x 7/8” x 3 1/4". I carved the Wing Fairing Bottom to conform to the bottom of the wing. See the picture of the Wing Filler
Old 02-20-2010, 03:55 PM
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Default RE: Dirty Birdy Instructions Update

Completing the Airframe

1. If you have left the fuselage top square and sanded flush with the sides, it will now be an easy matter to lay out and cut the slot for the fin in the top of the fuselage. I left the slot short of the aft end of the fuse and cut a corresponding notch in the fin. This is not necessary if you want to just cut the slot all the way to the rear that works too.

2. After fitting the stab in paragraph 2 of this step, I go ahead and hinge the elevators (step 5). It’s much easier to do this before mounting the stab to the fuse.

I also think this is a good time to go ahead and do the wing fillets (step 10) and carve the fuse. The fuselage is just easier to handle without the stab.

When you carve the fuse, don’t carve back end of fuse bottom around sub fin or the very back of the fuse top around the fin. Leaving these areas square for now will help to get everything in the back end true, you can touch up the shape in the back later.

Remember the triangle stock you glued into the corners of the fuse? They mean you can really do a lot of rounding on the fuse. I carve well down into the triangle stock, the sides and top don’t even touch any more. Look at final pictures to see how much rounding is possible.

You can also do lots of shaping to the nose. I carve everything down so the lines flow smoothly from the fuse to the spinner. I had an old damaged spinner which I mounted and sanded down to for a perfect fit.

9. Since I covered the fuselage with MonoKote instead of glassing and painting, I mount the canopy after covering. Whatever you do, do not use CA to glue the canopy, it will fog the plastic.

10. I do the finish sanding later.

All of my control surfaces have hardwood inserts for the control horns because I use Dubro Heavy Duty control horns that bolt through the surface. The rudder already has a hard point built in. In the other surfaces, I drill a 1/2" hole through the surface and epoxy in a piece of 1/2" dowel cut to fit. Then sand flush.

Since this plane usually turns out nose heavy, I build a battery compartment in the tail, just in front of the tip of the sub fin. If you choose to do this, plan out where your pushrods will pass. See the picture of the Tail and Hatch.

While on the subject of pushrods, I prefer a dual pushrod for the elevator but not forked in the back as is described in step 12. I run two separate 4-40 steel pushrods the full length and solder them together just shy of the servo as shown in the interior picture. It’s basically the same thing as the Dual Elevator Pushrod System as shown here http://www.centralhobbies.com/contro...age/deps1.html but made with steel pushrods. There is a good how to link from that page too.

I don’t bother with the “ladder” support. In this plane using the steel 4-40 pushrods, being supported on the two ends is sufficient. Again, this plane usually ends up nose heavy so I don’t worry about the steel pushrods in the tail.

In order to get the pushrod runs very straight, lay them out from bottom and sides with a straight edge to find the exact point where they should pass through the fuse side. Also factor in the angle and determine where the angled hole should start. Then to drill the hole at this steep angle I use a long piece of brass tubing the same size as the outer pushrod tube. Sharpen the inside of the brass tube with a pointed Dremel stone. Chuck the brass tube in a drill and you can cut a beautiful hole at the angle you need through the side. The picture of the Tail and Hatch shows where my pushrods exited.



After completing step 15, I go ahead and remove all the equipment and now I do the final filling and sanding.

Cover using your favorite method.

The CG location on the plans is an excellent starting point.



If you have found these notes useful or have suggested updates, please let me know. I hope you found them helpful.

Dave
Old 02-20-2010, 04:56 PM
  #8  
doxilia
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Default RE: Dirty Birdy Instructions Update

Dave,

excellent idea and wonderful looking DB!

I'm sure I'll enjoy reading your notes and applying your suggestions to my UFO 25 build later this year.

David.
Old 02-21-2010, 07:13 PM
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dbacque
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Default RE: Dirty Birdy Instructions Update

David,

I hope you find some things you can use. There are some general methods and tips but you'll have to pick through it as it's really a suppliment to the original instructions.

Good luck,
Dave
Old 02-22-2010, 06:23 PM
  #10  
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Default RE: Dirty Birdy Instructions Update

dbacque,

That is one sexy looking Dirty Birdy.

I really appreciate you taking your time to post the updated instructions for the rest of us....[sm=thumbs_up.gif] They should be very helpful, especially to someone, like me, who has never built a Bridi kit. I too, have a Bluejay Dirty Birdy kit. I hope to build it light enough to use my ST60BH in.

David
Old 02-22-2010, 06:51 PM
  #11  
dbacque
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Default RE: Dirty Birdy Instructions Update

That engine should be fine in a Dirty Birdy. I've got an old Magnum .65 in mine and it really cruises!

You shouldn't have any problems building the DB. It's a little more work than more modern kits but honestly, it's a very fun plane to build. It's what I consider "real building".

Dave
Old 02-23-2010, 08:25 AM
  #12  
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Default RE: Dirty Birdy Instructions Update

Dave, Thanks for taking the time to jot down some notes and then sharing them with us! I've printed them and put them in my kit. Good stuff!

FB
Old 02-23-2010, 10:13 AM
  #13  
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Default RE: Dirty Birdy Instructions Update

Dave,
Excellent work. One thing I don't see - unless I just missed it, is drilling holes in the ribs for the servo leads to pass through prior to assembling the wing panels.
Old 02-23-2010, 11:28 AM
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Default RE: Dirty Birdy Instructions Update

Good one Jeff!

In fact, why not drill out the ribs generously. Something like what's shown in the photos below.

David.

Edit: I decided to pull most of the post as I realized after my errand that much of it wasn't really Dirty Birdy related.
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Old 02-23-2010, 02:54 PM
  #15  
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Default RE: Dirty Birdy Instructions Update

ORIGINAL: dbacque

Add the Tip Blocks. Carve tips flush with wing using razor plane (cover sheeting with blue painters tape first). Get tip close to shape of airfoil, then sand everything flush. Mark center line around outside of tip block. Now carve everything to shape.
Dave,
For the wing tip blocks I might also suggest tack-glueing them in place with a couple drops of med CA, carve and rough sand to shape, then pop the tip block off and hollow. (pictures in my build thread)

A good centerline mark is helpfull as you suggested. One thing I've done before is to either, use two blocks, or split the block in half and glue the finished edges together -using the glue line as reference to the centerline. The glue joint also helps protect against hanger rash if the tips are carved to a point.
My old Bridi instructions make mention of in-laying 1/64" ply at the centerline to make the tip more durable. I didn't think that was nessasary since I glassed mine, but if you're using an iron on covering, you may want the hanger rash protection by adding the ply or dripping some thin CA on the tip of the tip block.
Old 02-23-2010, 05:31 PM
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dbacque
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Default RE: Dirty Birdy Instructions Update

Yep, in my second paragraph on "Paragraph 4" of The Wing Panels I mention drilling holes in the ribs if you're using servos in each wing panel. But I sure didn't go to the extreme that David did. Looks like you've either got a major rodent problem or you really like swiss cheese! ;^)

Hollowing the tip blocks is mentioned in step 22 of the original instructions. I didn't bother to reiterate stuff that was already in the instructions. As a matter of fact, I did hollow mine some. Actually I only hollowed one as the wing came out slightly unbalanced, even after I weighed every part while building.

I also did some serious hollowing on the Fuel Tank Compartment Top Block (step 5). But I did't take into account just how aggressively I was going to shape the nose. So when I carved the fuse I wound up cutting through to the forward corners of the hollowed area. No big deal, I just whipped up some epoxy and microballoons to fill the area from the inside and kept right on shaping.

On my first DB, I did inlay 1/32" ply into the centerline of the wing and stab tips. I didn't bother on this one for some reason. When I do this I usually wait until after carving and just cut a slit with an X-acto knife. Then you can just slide pieces of 1/32" or 1/64" into the slot and CA them in.

One thing that I do on the wing tips that I didn't mention is that because the trailing edge of the wing tip gets so thin and is succeptable to damage, I cut about 3/8" of the TE off after it's carved, glue on a piece of spruce for the wing tip TE and carve it down to shape. I think you can just barely see it in this photo.

Another thing you can see in that photo is a hole in the rib. I like to make sure all rib bays are vented to prevent the covering from "pillowing" when you use the heat gun. The easiest way to make vent holes in the ribs is a single hole punch like for use on paper. It works great! As a matter of fact, I used the hole punch to make the holes for the servo wires. I just punch two or three overlapping holes and trim with an X-acto.

Dave
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Old 03-03-2010, 09:27 PM
  #17  
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Default RE: Dirty Birdy Instructions Update

Well, what a bummer. The site that I referenced that has the original RCM article on the Dirty Birdy no longer has the articles. I wish I had made a copy of then while they were up. It was very interesting to compare the original plans and instructions with the current kits and it really helped me to understand some of the inconsistencies in the instructions.

I'll leave the link in the notes just in case it comes back but don't be surprised when it doesn't work. Sorry.

Dave
Old 03-16-2010, 09:43 PM
  #18  
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Default RE: Dirty Birdy Instructions Update

Interesting thread, I am building a BlueJay Dirty Birdy and had to change a lot to the nose to get the motor to fit[:@] went from 2 1/4 to 2 3/4 inch spinner siize. Man I can not believe how wide this Irvin 72 is. Turned into a custom build all the way. Interesting plan's and instructions with this bird. . Now a lot of SANDING[:@]
Larry K
Old 03-17-2010, 02:27 PM
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Default RE: Dirty Birdy Instructions Update

dbacque

Here's the article. I sure would like of copy of the build intructions for the built up version DB 60 if available. I tried to dl yours but it says the file is corruped and won't dl.

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Old 03-17-2010, 02:32 PM
  #20  
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Default RE: Dirty Birdy Instructions Update

For comparison here's the build instructions for the glass DB60 and the materials list.

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Old 03-17-2010, 04:23 PM
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Default RE: Dirty Birdy Instructions Update

Hey, I knew somebody here would come through with the original DB article. Thanks Roguedog! It's interesting to compare the original article with the current plans, it really did explain some of the confusion in the fuselage construction.

So are you saying that you couldn't download the first file in my first post here? They're just a PDF of the next 6 posts. But it loads fine for me.

I didn't scan the original parts and instructions but I can do that for you if you'd like a copy.

Dave
Old 03-17-2010, 05:36 PM
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Default RE: Dirty Birdy Instructions Update

Dave,

Glad to help.

As far as the PDF,yes I can't open the very first PDF in your first post or download it by right clicking,. I was able to open and download the other "attachment.pdf" files just fine. Hmmmm. I would have liked to have that file. Just tried again and for some unknown reason can't get it.

PM you.

Bryan
Old 03-17-2010, 06:12 PM
  #23  
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Default RE: Dirty Birdy Instructions Update

Bryan & Dave,

I re-built the PDF file to see if that might help to download. It is also a tad smaller now - 81 KB. I hope this one works for you Bryan.

The page order is reversed but all the pages are there.

David.
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Old 04-21-2011, 09:54 PM
  #24  
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Default RE: Dirty Birdy Instructions Update

Hi Dave ,

Thanks so much for the effort you put in by posting your building notes. I used them extensively while I built my Dirty Birdy from the Bluejay kit. I found the kit to be well done, good balsa and definitely old school in the building techniques. Your notes on incidence and the 1/8 longer stab on the plans really helped avoid inaccuracies. Mine has some Rhom retracts, an OS 61 FSR with a Supertigre pipe and the fuselage and vertical stab are glassed and painted. All up weight ( with 4 ounces of tail weight) is 7 pounds 3 ounces. I await decent flying weather here in northern Minnesota to maiden it. Thanks again!

Chuck
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Old 04-22-2011, 03:55 AM
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Default RE: Dirty Birdy Instructions Update

WOW ! ! ! !

What a beautiful DB. Good luck with your maiden.....

David

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