Here's a picture of my latest project, a Dirty Birdy 60 from the Bluejay kit.

The kit was beautiful. Good wood and excellent machine cutting, nothing damaged in packing or shipping.

Construction went almost without a hitch. The only problem encountered was that the plans appear to have the wing at the wrong incidence. Instructions and printed text on the plans say 1/32" - 1/16" positive incidence on the wing but the plans (and I understand that these are the original Bridi plans) have the wing at 7/32" positive and the parts are cut exactly to plans. I came out with exactly 7/32" positive incidence. You are expected to adjust the incidence and work the wing saddle to fit, but after doing that the wing didn't line up with the wing dowel holes in the former. No problem, I just plugged them and redrilled. I think the answer is to wait until you set the wing incidence before drilling these holes.

I don't know if the original kit had the cutouts already done for the stab and the fin, but this kit didn't. Not a problem, just interesting. A quick tracing of the fuse aft end, stacking the sides and a trip to my band saw took care of the stab cutout. When I went to install the fin, the instructions said to insert the fin into the slot. Slot, what slot? Again, not a problem. Just marked a center line and quickly cut the needed slot.

Other than that, every thing fit perfectly and it was a joy to build. I love carving balsa to shape and this had plenty of carving to satisfly me.

While the Magnum .65 wasn't my first choice for power, or even my fourth choice, it was free and unused. Yes, retracts and a hot, piped engine would be gravy but this plane is still solid meat and potatoes. I also opted for MonoKote instead of glassing the fuse. Sure, it'll be more prone to hangar rash but this is purely a sport plane for me and this was quick and easy.

The plane turned out a little nose heavy but a battery compartment in the tail compensated for that and all up flying weight is 6 lbs, 2 oz.

The DB made it's first trip to the field today and I must say that I was impressed! After the initial trim settings, I spent some time making long level passes. The plane looks great in the air and really holds attitude without fiddling the sticks. A few half reverse cuban eights, loops and cuban eights and I was starting to get a feel for the plane. Rolls are very smooth but I need a little more throw on the ailerons yet. Vertical lines both up and down hold straight and true with no tendency to pull out and from level flight it pulls up to a perfect vertical line. Then try some some stall turns. Wow, how sweet!

The first day at the field was cut short when the engine started sounding funny. I landed and found the back half of the muffler barely holding on. I hadn't thought to remove the bolt and lock nut and locktite them. Luckily I got it down before I lost anything.

So tonight I'll up the aileron throws, tighten and locktite the muffler bolt and this baby is going to see a lot of flying this fall!

Dave

dbacque, great monokote job on the fuselage it, if you didn't mention it I would have sworn you painted it. What club do you fly out of Houston?

Nice looking ship, dave

Very nice Dave!

Makes me miss my old DB!

Does anyone know where to get a slightly different style DB canopy? The one in dbacque's picture is the most common one I've seen, but I seem to remember one that tapered down to more of a point in the back...

Joe W.

I have the Blue Jay Dirty Birdi 2+2. Just like yours. Excellent wood, excellent plans. Now all I need is time to finish it.
GPB

Gorgeous model, Dave! Truly excellent job on the wing saddle/fillets, too. I wish I could Monokote like that.

vellum2, Wing Mfg sells a slightly different canopy of about the right length. roncoleman posted a photo of his Super Kaos with that very canopy in the Kaos Sticky at the top of this forum.

Thanks for the nice comments guys. As I said, this was a very enjoyable build.

Actually the wing fillets didn't turn out as great as you think! After doing the fillets, I remounted the wing to find that the outer points of the fillet base had pulled up from the wings. Aaargh! (Hey, it IS talk like a pirate day!) But like everything else on this plane, the fix was easy and apparent. Whip up some more microballoons and epoxy, mount the wing to the fuse with some release plastic double stick taped to the wing and slop the stuff in the crack. What would we do without microballoons? After slopping that junk in the fit was perfect. And the MonoKote hides all the work!

There are a couple of threads on this fourm that discuss the DB canopy. I boomarked them when I ordered the kit but I deleted them a couple of days ago so I can't reference them at the moment. I used the canopy that comes with the Bluejay kit. Seems like someone said that Wing Mfg. has one that closely matches the original. Someone else said that the original is still available but I don't remember where. Just like the motor, the fixed gear and the MonoKote, I had this part so I used it.

Speaking of MonoKote, the cream MonoKote was the left overs from a BUSA EAA Biplane that I built 17 years ago. I was surprised to see how much MonoKote has changed. The old stuff was much "harder" and doesn't stretch as much when being applied. It even sounds different. But when heated, it shrinks more and faster than the new stuff. It went on fine and I had no problems. I really think I like the old stuff better than the new. The challenge on MonoKoteing the fuse was the wing fillets. What I did was to put a couple of coats of Balsarite on the fillets, sand and then apply a piece of covering just on the fillet. Worked great. Then I overlapped the covering on the fuse side.

I'm a member of the JSCRCC http://www.jscrcc.com/index.htm, we fly at the NASA Johnson Space Center. Very cool flying where you work. Stop in for a couple of sunset flights on the way home!

Dave

Here is the canopy I ordered for my UFO. I believe they are leftovers from the GP DB kits.

http://www2.towerhobbies.com/cgi-bin...?&I=LXJ932&P=7

Wing Mfg sells just the canopy, and a "kit". I believe it is CK-604. Here is a picture of my new King Altair with that canopy kit.

That's the one AVL! Thanks!

Joe W.

I got to really fly the DB today and all I can say is WOW!

I've got the aileron throws increased and now that heavy feeling is gone. It's smooth when you want it but will slam around with the best of them.

I've still got the CG as shown on the plans. I always like my planes tail heavy but this really feels just about right. As I said, the down lines are perfect, with no tendency to pull out, even as it builds up speed. I worried about the 2 degree down thrust built in as shown on the plans, it just looked wrong. Especially once the fuse was built and the engine was sitting in it. Looked like the engine was falling out. But that feels just about right too. No trim changes from full throttle to idle down to slow flight. And once the nose was carved you couldn't see it anyway.

Now that the Magnum .65 has a few tanks of fuel through it, I leaned it out a bit and the plane really got up and moved. Not unlimited vertical but plenty of power to take it through huge maneuvers without any tendency to fall out at the top. I was really concerned about not using a hotter engine but the Magnum flies this plane just fine.

Knife edge is very nice, no tendency to pull to canopy or belly and no tendencies to roll. One particularly long knife edge pass I thought I noticed some proverse roll but later passes I had a hard time seeing it. I'm sure once I've been flying it for a while I'll mix in a click here or there but at first look it's about as true as any plane I've ever flown.

Inverted requires just a slight touch of down, again the CG from the plans feels just about perfect. Inverted outside loops are big and beautiful!

As I got to more aggressive maneuvers I bumped the rudder up to high rate and then I had the snaps and spins that I expected. Snaps are fast and with instant recovery.

After a few flights, I burned most of a tank of fuel doing touch and goes. Man, this plane lands like a dream!

No matter what I threw at it, the Dirty Birdy performed flawlessly. And with no computer mixing. I am some kind of impressed!

Dave

Dave, that's really great news. I'm dying to get my UFO finished and in the air. From what I understand most of the UFO's refinements which Bridi made to the DB address slow flight performance, e.g., thicker stab airfoil for more drag with anhedral to get the elevator out of wing turbulance, and thicker wing section for better speed consistency, and also more side area for KE and a slightly longer tail moment.

Assuming I've built a straight ship, I hope mine flies half as good as you describe yours. No matter how good the design, it all comes down to the building and you've clearly done a great job. Now, get some video so we can see it flying.

Thanks, David

Boy, you got that right, Dave (design not as important as building it straight - or something like that).

When I lived in NJ I was a block or two from the Delaware River, right where it begins transitioning into the Delaware Bay. Humidity was always a problem. I nicknamed my basement "The Divining Basement". Why? Put a piece of wood down there that is straight as an arrow and within two weeks it will be warped and bowed. It made building straight model airplanes flat impossible. Once, I had a friend build a wing for my Deception (my first attempt could have been used as a propeller). My friend, Syd Clement, gave my wing the full treatment on his glass hotel door building table (with micro adjusters) and built me the straightest wing I've ever had. Two weeks in my basement and it was useless. I needed to run a dehumidifer, but couldn't get to it financially at that time and still have enough money to fly. Many of you know how that goes.

Now I have a great building area, but the eyes are problematic. Near vision stinks. Now I know how apprenticeships were created by the old masters. <G>


Ed Cregger

Dave,

Awesome looking plane[sm=thumbup.gif]. I just ordered my Dirty Birdy 60 and pictures like yours makes me want to build mine ASAP. In you opinion, do you think there is enough room in the wing for retracts? I plan on making mine a tail dragger and I was just wondering.

Fly safe and have fun!!
David

Seems like the plans did say something briefly about retracts. Like maybe, install retracts if you want to. I'd imagine they'd fit in the wing just fine.

Thanks for the nice comments. Oh man, do I love this plane! Even after a year of flying it, I enjoy it more every trip to the field.

Dave

Dave,
Good job. Your DB looks great. I am glad to here it flies so well. I am just finishing a plans built Dirty Birdy of my own. I painted mine and am just putting in the radio gear. Mine came out very nose heavy. If I put the battery at the rear of the wing saddle area I will still need about 3 or 4 ounces in the tail. Can you explain exactly how you put the battery in the rear? Possibly a picture? This sounds like a good solution to my ballance problem.

Thanks
Jim

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I'm glad that you are happy with your new Dirty Birdy.

I noticed that even the Dirty Birdy 40 shared many of the fine flying qualities of the 60 sized model. While the Super Kaos 40 flies very well, to me it does not fly similarly to the 60 sized version.

I'm a firm believer in foam wing cores when using retractable landing gear. It is so much easier to construct and it is much more robust, as far as I'm concerned. Of course, I'm basing this on seeing others models with built-up wings and retracts with broken ribs sticking up through the covering. It could have been that no wing type could have withstood such a landing, but the foam always seemed so much easier to build and maintain. Yes, I have built and flown foam winged versions.

I have a Blue Jay Bridi kit of the DB 60. But I'm thinking about buying foam cores and installing conventional retracts. You can always leave them down for SPA flying. SPA doesn't outlaw retracts, they just insist that you leave them extended while flying in their competitions. Sounds reasonable to me.


Ed Cregger

Great job on the DB! The color scheme and trim is very classy looking. I was thinking of going with cream with maroon trim on my next bird. Prop

This was a Bridi kit from the late 70's. Had Kraft electric retracts in it. Blue head super tiger. Excellent flying airplane. Have the plans for a new one to build in the near future. Probably will use a Robart retracts and maybe a tiger 90.

I cut a hole in the bottom sheeting just in front of the lower fin. Then I built a box in it and made a ply door. I would have liked it farther back but the ventral fin made that impractical. Even so, it saved several ounces.

With a 5 cell NiMH pack in the hatch and servos all the way back in the radio area, I only needed 2 1/2 ounces on the tail. I think initial estimate was around 7 ounces of weight on the tail so this saved a quarter pound of lead!

Dave

Since I've been flying this plane for one year now, I figure this is a good time for an update. Especially since the Bluejay kit is available once again.

I just got home from the field and made something like 10 - 12 flights today. This plane is fantastic! It's the only thing I take to the field any more.

I flew the DB balanced according to the plans and with no mixing for better than 6 months. Finally I moved the CG aft a little to improve the down lines. Balanced per the plans, it had a very slight tendency to pull out in vertical dives. I added tail weight until the down lines were true. This took an aditional 1 1/2 oz. Snaps and spins improved with the CG adjustment. But with the new CG, the plane doesn't like to sit on the nose wheel with the tank empty. If I built another, I'd probably move the main wheel blocks aft about 1/4" or so. But I've always liked my planes a little on the tail heavy side.

I know I balanced the wings during construction but I've also got over an ounce of lead on the left wing tip to make the roll trim match upright and inverted. Some of it may be due to the muffler but I guess mostly I didn't balance it very well. Oh well, so I've got some lead stuck to the bottom of the wing tip where I never see it anyway. The plane trims out perfectly, who cares!

Knife edge has always been good but lately I've been working on some mixing to tweak the very minimal cross coupling. The plane had a little bit of roll to inverted and a very slight push to the belly on knife edge. Nothing that couldn't be managed easily but the mixes are really nice. I tweaked my mixes again today and I've currently got 4% rudder mixed to ailerons and 2% rudder mixed to up elevator. This puts the knife edge just about spot on. Knife edge clear across the field rarely requires anything but rudder. I think on the times that I do need to bump the ailerons, I probably didn't set up the pass correctly. Best of all, point rolls are ruler straight.

Engine thrust line is set exactly per plans and pulls to vertical are perfectly true. I haven't shimmed the thrust line since it came off the building board.

I built mine with fixed gear. Retracts would have been cool but this is just a knock around sport plane for me and it fits the bill perfectly.

While the Magnum .65 wasn't the engine I wanted to put in this plane, the cost (FREE!) was just right. After flying for a year, I've never once been disappointed with the performance of this engine in the DB. Maneuvers are just as big as you want them to be with no tendency to fall off at the top of huge loops or vertical lines. Square loops track accurately even in the up to top corner. So there's plenty of pull and plenty of speed. If a (new) 18 year old Magnum .65 will pull this plane this well, I'd say any modern .60 class engine would be fine. And if you can get one a little lighter than the Magnum, so much the better, I needed 2 1/2 ounces of lead on the tail and the battery mounted in the aft of the plane, just in forward of the subfin just to get the CG to the location on the plans. With a .60 class engine flying the plane for all it's worth, I'd be leery of using a larger engine. You'll really be packing the lead on the tail and the upping the overall weight.

So my impression after 1 year of flying? I love this plane! And the only thing I'd change is the main gear location as mentioned.

Oh, if you're thinking of building one, and you should, do see my notes in the first post about drilling the wing dowel holes after setting the wing incidence.

Dave,
Thanks for the description and pictures of your battery compartment. On mine the pushrods were in the way to put a compartment in that location. I ended up making a compartment about half way between the wing opening and the subfin. It as accessed from the wing opening. Thanks again for posting pictures of your compartment.
I hope mine flies as good as yours. I will post a picture and a description of mine when I get it finished.

Jim