25% Cessna L-19/0-1 Bird Dog build (Full Version)

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khodges -> 25% Cessna L-19/0-1 Bird Dog build (1/1/2008 10:34:28 PM)

Hi guys-- After three years of sitting on a shelf, the 'Dawg is gonna finally get built. Here are the details:

Vaillancourt plans, 1/4 scale (108" wingspan)
Laser-cut kit done by Larry Katona & Precision Cut Kits
Motive power will be a ZDZ-50NG, turning a 22" prop
Radio will be 2.4 GHz
It will be built as a Vietnam-era Army spotter/FAC, the exact plane yet to be determined.(see comment below)
Wing hardpoints will be set up to mount any of the underwing items the BirdDog used, from twin rocket pods, to 7-shot pods, to M-60 MG's, and maybe even loudspeakers (used for propaganda purposes, the L-19's were called "Bulls**t Bombers"[:)]). I'll scratchbuild these items as needed.

I doubt if I'll compete with this plane; I want to build something representative of all the 'Dogs that flew in S.E. Asia, instead of a single model of the type. In doing this, it would not qualify in a scale competition, but the prime purpose is to show what the L-19 was capable of and to honor all the guys who served as FAC's in both the Army, USAF, and USMC.

I'll probably get off to a slow start, but here's some pix of how the pieces look:
1st is the kit; very complete, I couldn't believe the box wasn't 3 times as big to get it all in. Firewall, gear plate, and a few other structures needing extra strength are hobby grade ply, the fuse formers, cabin sides, elevator and rudder T.E.'s are lite ply. There are hardwood sticks and balsa sticks and sheet; everything is organized, with either a sticky label or laser etching to I.D. the parts. All the wing ribs are bagged together, and the smaller parts are also bagged together, very nicely packed. Wood quality is excellent throughout. Based on how I received this kit, I would highly recommend Precision Cut Kits. I know that I have seen questions about them recently, but this kit is well done.

2nd picture is the cowl, which I ordered through Vailly Aviation, as well as the landing gear and main gear wheels, which are in the 3rd and 4th pics. The wheels are machined aluminum, and the tires are Sullivan 5" diameter. The landing gear is 3/16 aluminum 6061 T6. I may look into having a set made from spring steel like the prototype; depends on the weight.



khodges -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/1/2008 11:00:26 PM)

Now that I have all the pieces parts, they do little good without something to show how to put them together into some semblance of a flying machine.

Vaillancourt's plans are full-size and are four sheets, three feet and a few inches wide, and almost ten feet long. They show every part in planform such as the formers and ribs, in case you need a template to make something (or obviously, to cut your own kit, if you're not too lazy, as I was, and get somebody else to do it for you[:)]) Notations are made for incidence, dihedral and washout for the wings; this plan has no right thrust designed in, and I will not add any.

There is a photo pack of the build-up of the kit from Vailly, and I bought it. There are a few "holes" that the pics don't fill in, but I don't believe it will be a problem. It is also obvious here that Roy figures that the builder will know what needs doing and how to do it.

For details, I have a couple of hundred pictures of two L-19's in my area, both recent restorations; one is an "A" model, one a "D" model; one is done in Army green, the other in USAF gray. The other reference I have, and will be my "bible", is a book called "The Lovable One-Niner" by a gentleman named Minard Thompson. It has complete info on all variant specs, markings, flight performance data, engine specs, technical specs on what radio with what model, etc, you name it, it's in there, along with a couple hundred color and B&W photos. There is also an index of ALL serial and tail numbers of all the L-19's built, with where they were first assigned. Lots of crash pictures, too[:o]

Here's a few details from the book; I give full credit on all reproduced photos and/or pages from the "Lovable One-Niner" to Minard Thompson:



jhcorsair -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/2/2008 12:19:54 AM)

Those Bird Dogs had plenty of power when you needed it. Gliders used to drop in my dad's airstrip on the farm (1800 feet) and the L19 was sent in to pull it off no sweat!



RICKSTUBBZ -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/2/2008 12:35:36 AM)

Hey Ken,
I found it without a problem. With what I have seen of your work so far, this will be a great bird. No pun intended.



khodges -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/2/2008 3:09:21 AM)

quote:

ORIGINAL: jhcorsair

Those Bird Dogs had plenty of power when you needed it.


They sure did. Rated at 190 hp @ 2300 rpm for most of its operating range, it was rated for take-off power at 213 hp at 2600rpm for 5 minutes. (Continental O-470-11 or -15). The earlier models with gross weights of 2100 lb could take off in 355 feet and clear a 50 ft obstacle in 580 ft.

I laid out the tail feather plans, and set out the pieces, mainly to inventory them and get a feel for what I need to do that the instructions (aren't any written ones) don't say. I'll build the tail feathers first, to get into the swing of things. The first thing I noticed is that the trailing edges of the rudder and elevators are cut from 1/8" lite ply and are sort of flimsy feeling. This is only three plies, and they were cut with the outer plies going the short way. One of the elevator T.E.'s was broken; I decided then to re-cut these pieces, using 1/8" hobby ply, which is 5 plies, and to run the outer plies long way, which stiffens the pieces significantly.

Also, according to the plans, both halves of the elevator receive a small block for a control horn. On the full-scale, there is only one horn for the elevator, on the left hand side. I'll build mine this way, so I'll also have to fabricate a joiner for the elevator halves that will not flex and allow aerodynamic loads to twist it, which in turn lets one elevator deviate from the other in it's deflection under load.
Not sure what I'll use yet, but I have some carbon fiber tube that may fit the bill. The rudder only mentions one control horn, but I'll be using a pull-pull setup like the full scale.



redtail -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/2/2008 3:59:52 AM)

Hello there, all construction on my 1/4 scale Vailley Bird Dog has just been completed. Just finished primering the fuse, tail feathers, and cowl. The wings are about to be glassed. I will be more than happy to give you any tips on the construction but the best thing you can do is get the construction CD from Roy which helped alot. Also, I will look up the website of a Bird Dog construction website which was extremely, extremely helpful to me. Among other things, it showed construction of a jig to build the fuse on, etc. Worked great. If your interested send all of your email to my personal email address. It is redtailpilot@aol.com I did a few extra things to make Roy's Birddog just a bit more scale. I also believe I have an extra cockpit kit for the Bird Dog from Dynamic Balsa. I'll sell it cheap, I do not need two. Smile. Chic White



khodges -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/2/2008 7:58:00 PM)


quote:

ORIGINAL: redtail

Hello there, all construction on my 1/4 scale Vailley Bird Dog has just been completed.


Post some pics, I'd like to see.



redtail -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/3/2008 1:33:33 AM)

Hey Ken, would love to show you pictures of my bird. I will do so as soon as I learn how to post pictures. Chic



redtail -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/6/2008 2:34:04 AM)

Ken, here goes my first attempt at posting photos on the web.



khodges -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/6/2008 5:38:59 AM)


quote:

ORIGINAL: redtail

Ken, here goes my first attempt at posting photos on the web.


Redtail, all I can say is, WOW! You have certainly set the bar at a height I'll have to work damn hard at to reach. That's beautiful, even in primer. I especially like that you did the FM homing antennae on the H stab. Will you fly it with them, or do you think there's little chance for the lower antenna to snag in the grass?

What references are you using? Did you get a photo pack (like Banka's) or did you have a full scale to detail from?

Things around here are conspiring against my getting a good start. We've had washer/dryer problems on the home front, and had to get that taken care of to keep the wife happy and the family in clean clothes, I'm doing some grading and landscaping work at our field, trying to get some grass going while there's enough moisture in the ground (it actually has rained here twice in Dec.) I've delayed starting the tail feathers; after looking through all my pics, I don't have a really good photo of the rudder and elevator hinges, and I want to replicate them as closely as possible in aluminum and brass, so I've got to arrange a photo-op at the grass strip down the road where a BirdDog lives. While I wait, I'm going to do some detail work on the cowl, by marking where the access panels will get cut, and making the panels themselves. I remeasured the engine I'm using and am disappointed to find that the spark plug cap will require a relief hole in the bottom of the cowl. I really don't want to do that, so I may look at a different power plant, something that has an angled plug. I'd love to do a twin, but don't know if I can find something in the 45-50cc range that will fit the cowl without having the same problem on the sides. I have a Quadra 35, which is what the plans show, but I want more power. I might use the US-41 I also have, that's on another plane. It is similar in size and weight to what the L-19 will be, and the -41 does a good job with it, so I might go that way. What are you using?



redtail -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/6/2008 3:42:34 PM)

Many thanks for the comments Ken, all I can say is "Go to school off of the problems I and others went through in building this airframe". That is why I say, email "Roy" at Vailley Aviation for "anything", he is some kind of great. As noted, he sent me a paper on how to build in the washout, etc. First to answer your questions, I will fly the model with the FM Ant installed. I am trying to figure out something flexible to install like the full scale bird so that brushing through the grass won't have a heavy impact. 2nd, yes I have two photo packs, one from Banka and one that is a 17 picture calendar done on the L-19 Bird Dog (www.lulu.com), color scheme will be overall white with red tips and tail feathers, I have the same book you have and I also have the Squadron "In Action" Series on the Bird Dog. 3rd., Smile, trust me with regards to the household stuff, I too have just replaced the washer/dryer, tree removal, replacement of 15 windows - $$$$$$, so my progress has been slowed to a crawl. Heck, I have a Meister P-47 and a Kellogg TBM Avenger in the wings. Anyway, I will be using a Zenoah 45 which fits just perfectly in the cowl without any, any, any unnecessary holes other then the exhaust slot across the rear of the cowl. 5th., I am using the large Robart pin hinges which looks pretty darn scale, 6th, I too will be cutting holes in the F/G cowl which I will then cover with 1/32 plywood access panels. 7th, I greatly modified the top cover for the fuse, (Observation Windows). Initially, I decided that the rear portion (two windows) will be more or less permanently installed. The front portion (four windows) will be removal to get access to the wing bolts and wiring. I used the plywood patterns from the kit as patterns and then enlarged the top cover to resemble the full scale. The new top extends beyond where the wings mate up with the fuse. It extends about an inch past the fuse edges. The kit patterns served as the base, then the plexiglass is layered onto the base and the new cover then layed on top of it all. I also have the new top curving around the leading edge like the full scale. Weights and windex helped the 1/32 ply curve around the leading edge. Again, if you want the copy of the rcscalebuilder "L-19 Bird Dog Build", just PM your snailmail address to me. Ready to help if I can. Chic White



balsabuff -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/6/2008 4:55:00 PM)

Chic, how did you do your corrigations ?



redtail -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/6/2008 8:14:02 PM)

Hey there, the corrugations are the result of using "Plastruct 1/16" Angle (90002), Catalog Number A-2. Matter of fact, I got a good deal on price by going onto Ebay and purchasing about 10 packs of the stuff. To prepare the wood, I put wood sealer on all the wood surfaces including the fuse, then f/glassed (wings yet to be done) all the surfaces using water based Poly. Great stuff as long as you use the wood sealer. Trust me, I'm speaking from rebuild experience. Then I CA'd the plastic angle pieces onto the surface. If there was a gap, I applied some filler, sanded then primered. Will use latex for paint. Chic



redtail -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/6/2008 8:21:03 PM)

Forgot to say that the wraps going around the leading edge of the rudder fin, elevator tips, rudder tip, and the horizontal stab were made using two layers of electric tape placed about 3/4 of an inch or so from the leading edge. I then gobbered a bunch of filler up to the tape and tapered it off as I came toward the leading edge from the tape edge. While drying, I peeled back/off the tape and let fully dry, I then sanded smooth the rear edge of the filler leaving a well defined and built up lip. From the lip I sanded toward the leading edge blending it into the leading edge. Worked great. Chic



Rmerritte -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/12/2008 3:02:29 AM)

Red Tail,
What a blessing to me! I'm starting a DOG andf am interested in all you mentioned on your message. Also a quote on the cockpit.
Thanks

Randall



khodges -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/12/2008 3:25:32 AM)

Chic (and everyone else)-- I e-mailed Roy, got an answer in hours. One of the things I asked was what scale deviations did he make when designing the plans. His answer, paraphrased:

1-The area where the wing meets the fuselage at the trailing edge, near the flaps. The fuse should be tapered here but would require the fuse to have a "jog" in it, just over the cabin door area. This was done to make construction easier for the average modeler. Some guys fix it, but most don't, and the judges "never pick this up"

2- The landing gear is thicker in section and wider in the side view. This is due to the materials used and the strength needed.

3- The H-stab incidence is 0 degrees shown on the plans. (The full scale's is about -2 degrees [kh]) In Roy's words: "The stab angle of incidence is adjusted to make the model fly...period. The scale angle just doesn't work for the model. Don't even think about fixing this one or you'll only fly it once."

Everything else is okay.

When I compared the wing root on the plans to the one on the full scale, I saw why the model looked ...fat... here. I dinked around about half the afternoon Thursday and changed my plans to correct this, but I'll leave everything else alone; well maybe the gear, if I can come up with something as light and strong as the aluminum (carbon fiber, maybe?)

I also decided that I will go with the LS50 twin instead of the ZDZ. I'll save it and stick it in my SPAD or D-VII down the road.

Looks like we'll have a whole squadron of these planes pretty soon.



mobyal -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/12/2008 3:41:05 AM)

Ken --
I'll watch this one. That's about the limit of my abilities compared w/ you guys....



khodges -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/12/2008 3:17:27 PM)


quote:

ORIGINAL: mobyal

That's about the limit of my abilities compared w/ you guys....



Nonsense, Mobyal. One of the reasons, I guess, that I haven't started this plane sooner is the intimidation factor. Looking at the plans, without a book to say, "glue this piece to that piece, but not until AFTER you ....." scares me that I'll make some irrevocable faux pas and ruin the whole thing. I'll wind up pinning half of it together to understand the relationship of the parts before I put the first drop of glue to it[:)]. I figure this will take me the better part of two years to build, mainly due to stopping to figure out how to best do the next step. I look at my WACO sitting on my build table, and I say, "this is a big airplane!" Then I look at the BirdDog plans hanging off both ends of the same table, and consider that the wing is three FEET longer than the WACO's wing, and I say, "OH, S**T!!![:)][:)]



redtail -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/12/2008 10:42:48 PM)

Hey there "Rmerritte", bad news with regards to the cockpit kit. It has been sold. However, depending upon where you are with your build, I can also send you a copy of the Bird Dog build thread that really helped me. If I can help, just holler. Chic



khodges -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/13/2008 9:43:50 PM)

I'm in the shop today, repairing one plane and starting another, at the same time. I've had some of my BirdDog pix out, looking at the rear wing root area that Roy mentioned was not exactly true to scale on the plans. When you look at them side-by-side, the difference is obvious. I made changes on the plans in pencil to see how much it would take to bring the plans closer to true scale as seen from the pictures. In order to make the model like the full-scale, only two formers need some minor changes, and the wing root must be given a small "jog" (Roy used the same term, works for me) at the rear near the flaps, and the inner end of the flaps themselves get a small modification to match the jog in the root. None of this is complicated at all, just requires mainly recutting two formers.

The first two pictures below are rear angle shots of the full-scale, showing the cabin roof and wing root area. Note how the wing root makes an angle at the area near the inner end of the flaps and the rear roof windows, and that angle is parallel to the outside edge of the rear roof windows. The plans have the wing root straight for ease of construction, so the rear window is larger than it should be, and the wing root does not follow the lines of those roof windows.

The third picture shows the fuse formers stacked with the front former on bottom (#3), then #4, #5, and #6, which is the first former of the tail cone, and #7. The large notch in the middle is the crutch location and the formers are aligned on this notch since the crutch is straight. Note how former #5 spreads out from the crutch upward, and is the same width at the top as #4. #4 is at the rear of the door, between the two side windows, and #5 is at the cabin rear and forms the front edge of the rear cabin window. Note also that the sides of the formers below the crutch are all roughly parallel. Stacking the formers gives a very foreshortened idea of how the fuse will twist and curve from front to rear.

The fourth picture shows the original #5 former next to the revised #5 former. Note how the upper portion above the crutch is much less spread out on the revised one.

The 5th picture shows the formers stacked again, with the revised #5 in place. Now notice how it sort of "bows" in a little below the crutch when you compare it to #4 and #6. This would give a small "pinched" area in the fuse when it gets skinned, as the sides of #5 are no longer parallel to #6. So, #6 also gets modified at the top curvature and a bit on the sides.

The 6th picture shows The original #6 traced onto plywood and the revision pencilled in. The original outline is in red so you can see where the change is made. Picture #7 shows the original former on the left, and the revised one on the right.

Finally, picture #8 shows the stack again, with both revised formers in place, which shows a smooth transition in the fuselage sides as it progresses from front to back, and gets rid of the "thick" area at the rear window, and will bring the wing root into proper location. The wings will be modified when built, to match this.



redtail -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/13/2008 11:11:43 PM)

Hey KH, you sure your not an aerospace engineer. Nice work with the modifications. I attempted to do simulate what you are doing by increasing the width of the top of the fuse area as seen in the pictures of my fuse top with the angled rear section in the wing root flap section. The jig that you will see in the stuff I'm sending you will work even with your new modifications since your modifications do not change the bottom of the fuse formers. You'll see when you read through the material. Keep it up, and keep copies of your new formers incase I might build another "Dawg" in the future. I am also installing wing hard points to drop a set of duffle bags like shown in the Bird Dog Book. Can't wait for your future posts. Chic



khodges -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/14/2008 3:58:32 AM)

Thanks, Chic. I'm going to set up the wing hard points so I can mount the normal wing racks, which will accomodate three different rocket pod setups, and am going to build a 1/4 scale M-60 to mount also. There were some wild things hung under those wings at one time or another, weren't there? How would you like to have been one of the paratroopers hanging under the wing that one of the pictures show? That must have been a helluva ride.



redtail -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/14/2008 11:38:49 AM)

KH, when I saw that picture in the "Dawg" book, there is no doubt in my mind of what those paratroopers must of been thinking before that puppy turned onto the active runway. Well, atl least he had two chutes. Smile. Told you Roy was good people to deal with, did you get the construction CD from him yet? It was key to my build because this was my first build from plans only. It is not a step by step, it just shows you a general idea of the different steps within the construction process. Combined with the stuff I am sending you this morning, you'll figure it out quickly. Time to get ready for work. I'm retired military who now teaches elementary school 6th grade math. Now there is a challenge for ya. Chic



khodges -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/14/2008 1:52:04 PM)

Chic, I asked him about the CD; he said he didn't have any and had changed his computer system since and had not set it up yet. He said that it was similar to the construction photo pack, but had more pictures. I did print the paper on washout from his website, it will help a lot and it confirms how I was planning to build my wings. I think with what I have and what you're sending, I'll be pretty good to go. I certainly appreciate what you're doing. I've made templates of the revised formers #5 and #6. PM me your snail mail address and I'll get them to you. I haven't started on the plan revisions for the wing roots and inner ends of the flaps yet. I'm going to wait until the fuse is framed up, so I can take the measurements of the angle directly from the fuse and get a closer fit. I will send you a pic, though, of the plans with the proposed change sketched on them.



Rmerritte -> RE: 25% Cessna L-19/0-1 Bird Dog build (1/17/2008 1:56:30 AM)

KH,
Ref the mods of former 5 and 6. I see pretty clear #6 but am a bit confused on #5! What is the distance across top of #5? Do you have drawings of 5 and 6? I'm studying the plans very hard and want to do this plane right. REPLY TO rmerritte@fl.easterseals.com
Thanks loads!
Randall



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