|Dec 25, 2005, 05:25 PM|
Fokker DR1 Guillows laser cut kit
The words Guillows and laser cut have not gone hand in hand, in past builds. I still am having trouble believing its a Guillows. Being laser cut, this Fokker builds very easy.
Building strong wings with automatic washout set by dihedral:
The picture should help explain all this.
The LEs of the wings were shaped using non-Guillows wood. The wood in this kit is above Guillows average, but is still a bit heavy. The LEs have a small groove cut in their rear sides, and a .060" CF rod is glued in thr groove. They are very strong like this. When setting dihedral, Guillows instructs to cut reliefs in the center spar and rear edge, so they will crack, to create the dihedral bend. I did this, but came up with a modification. A .060 CF spar was glued to the bottom center of the wings, leaving the ends free, where the wing will be bent to create dihedral. The CF spar sits in a relief, which is cut in the center spar, so that it blends in with the rest of the balsa center spar. Next bend the dihedral, carefully holding the wings, without breaking. This will take 4 hands, but I managed with 2. The unglued portions of the CF spar are now glued along the center balsa spar, doing 1 wing panel at a time. Holding the dihedral setting, clamp the CF spar to the balsa center spar, and spray activator, so you don't have to hold any longer, as it is a bit tricky. Glue CF horsehair or tape along the TE, across the center section and the relief cracks which were cut, to reinforce the now glued relief cuts on the TE. About 2-3 degrees of washout is now automatically set, since the CF rod reinforced LE does not bend as much as the center spar, where the dihedral was created. This causes the wing panes to flex, creating dihedral.
The center wing has individual panels. Washout there was simply set by end shims, used in the building process.
The elevator was laminated with cf hair along the main spar at the hingeline, on both sides. The 1/16"x3/32" balsa stick can use the extra strength. For hinges, it has been slotted for GWS plastic hinge paper.
For the rudder, running a very thin strip of balsa, say .030" around the outside perimeter, greatly strengthens the individual pieces that it is comprised of. Less chance of cracking a seam during the iron-on process, on this little part.
Hopefully with a light tail and batt directly behind the cowl the cg amy be able to be set. I saw a convincing one on RCG, where the guy stuck the motor out 2" on a stick, and had no cowl. I'm sure it flew great, but I'm too much of a scale fanatic for that. Considering that it has a respectable overall wing area of almost exactly 1sq-ft, maybe I'll overpower it with an Eflite 370 outrunner that I have laying around. At 1.6oz, it may have the needed front end weight.
|Dec 26, 2005, 06:48 PM|
Is that a fresh manufactured kit? I've been looking at the model for some time, thinking along the same lines. I'm sure we all have seen this kit sitting on the shelves at the LHS, and the one I looked at had dust on it. HHMMM Claybuster, the one in Utica. Now, the Prop shop might have one (surely you know where that is. ) Only place I have found locally, that has what we nneed. C-F, etc. And they talk electric ! ( well, some do)
I really like that tripe, just thinkin' about the challenge trimmin' it out to fly a little better than O.K. gets me goin' .
Was usin' CF your idea, or some one thinkin' out of the box? My big stopper was that one would have to set aside the stock balsa (true, for a rubber powered, you need some strength) and cuttin' ribs, formers, etc ., kinda held me back. Well, sub some new construction materials- CF, foam(s), et-al, would bring the weight down. (any kit makers listening?). Been lookin' at the micro- indoor section, and I gotta say , those boys know how to loose weight.
Usedta' fly indoor micro film, rubber powered, and been thinkin' about different covering options. Micro film was touchy, but LIGHT.( you can add dye to the formula, too). Gotta get closer to those indoor guys. (And, I lost the formula).
Gotta Guillow bird dog on the tile now, think I'm going to start weighting parts, and try alternate materials. I use those 2X3 or so ceiling tiles for building boards. Handy, pretty flat, and cheep. Some 2X2's, and you got a stack rack. Handy.
O.K., I'll shut up- don't ever get an old geezer started- ( Oops, I started myself this time)
HHMM, How about the Sopwith Tripe ? Those two looked alike ( I heard Tony Fokker reverse engineered a Sop. Tripe. True?)
What radio are you going to put into "Baby"?
11 Bravo, Out
|Dec 26, 2005, 11:49 PM|
Claybuster, I the span is 20" and its 15.5" long. What's impressive is the total span. If you connect all the wings together, it looks like something from a good sized glider.
Widgeteer, this kit was fresh. I have bought some dudty Guillows kits that were on the shelf for YEARS, in the past. The shop I got them from had not retagged them, and gave me at the original prices. I recently built a 25" Zero and FW-190 with stickers of $20.83. They had been sitting a while.
The triple wing setup without flying wires got me on the CF idea. I actually cut notches to recess spars in the wing main struts and braces. I don't want to see this triple wing setup crumble if it ever hits ground. Actually it should be pretty strong now. The CF dihedral braces and the CF reninforced struts all basically make point to point contact, so it is a well reinforced structure. The glue points will probably be weaker than any of the struts. Anyways, I got all the parts built up now. Need to start covering and figuring out how all the internals are goint ot go together.
On the lightweight micros, I still can't figure out how some of these guys get the planes so light. I wouldn't be surprised if the DR1 was designed from a captured Sopwith tripe. They are quite similar. Have to look that one up.
Got everything on the scale. Not trying to call anyone liars, but sometimes I wonder about some of the posted lightweights out there. Everything is built stock, with no more than 1/4 carbon fiber rods and spars. Weighed with geared IPS and 2s-340 lipo at 5oz. With GWS pico rec, Cirrus 4.4 servos, and Econokote red, I'll conservatively give this thing 6.5oz AUW tops. Considering 144 sq-in (1 sq-ft) wing area, it should fly with the setup.
|Dec 27, 2005, 11:04 PM|
Scratch, you are lookin' good. Talked to a pilot at Old Rhinebeck,( didn't rercord his name), kinda made me think he was hintin' that the tripe was like a kite without a string. With that rotary engine up front, like a big gyroscope, the tales of the pilots going in on the first flight where rampant. I guess the Sop. was similar.
Later- Went into the archives ( my book repository) and came up with some paperbacks that had some shots of Herr Von Richthofen, the day he went down. Book name is:The Canvas Falcons- by Stephen Longstreet. Paperback, some good pics. Next,Who Killed the Red Baron?- by P.J. Cariella and James W. Ryan. Some good pics there, too.
Sorry if I am boring you, but, alas, I have a great love of those "canvass wonders". I am sure you have seen the movie, with Errol Flynn "Dawn Patrol". Gives you some idea what those 'stick and canvass' wonders could do.
Are you going to use an out runner? I wonder if the' motor' case will give you the same or similar turning characteristics as the rotary engine? short span, etc.? I guess that setting control systems to minimum through would be a good idea, but what do I know? Best of luck.
About those micro guys: they are using mylar, etc. for covering. The indoor micro-film guys are wizards at light weight. They make their oun coverings, mix, pour on water, and lay on frame. (gotta have the frame below the film, ya know?) they make Props this way. ( I know, used to do it). Secret stuff. HaHaHa
|Dec 28, 2005, 07:22 PM|
Widgeteer, I heard of stories where the fabric comes off the top wing in a dive. The whole wing structure usually collapsed then, since they are all interdependent. I did, however, see 1 video where a guy was flying the devil out of a small ARF DR1. Can't remember the brand name. Hope its half that good.
On the build, I mounted the IPS gearbox inside scale rotary engine. I glued two pieces of rectangular plastic tubing to the back of the engine, for the gearbox mount screws to fasten to. Two small holes were put in the front of the engine case, to access the motor screws. This way, the motor can be removed, without even having to remove the entire gearbox setup. There is also a small clearance hole for the drive pinion, but none of the holes can be seen, as the cowl covers them. For the photo, the parts were simply stacked in place like a "card house". Don't bump the table before taking the picture. Pirated the Cirrus 4.4 servos and Pixie-7 from an unrealistic micro FW-190 I built in the past. It was simply to small for standard sub-micro gear. Maybe I'l get the Plantraco stuff someday, so I can revisit micros like it. The motor drew a whopping 2.15A at full throttle, so a small 2cell 350mah lipo should be fine. It actually sounded pretty realistic running out in the open, without the cowl. The turbulent air running across the fake cylinders made a simulated radial sound. Without the gear whine, it would have been very realistic. This little geared IPS setup feel pretty impressive. I think with the 1 sq-ft total wing area, it should at least be airborneable (I won't go so far as to say flyable) at 6.5oz or slightly under, I hope.
It seems that I will be able to set the cg without nose weight (absolute no-no), with the batt directly behind the motor (with a tiny bit of padding, of course), and everthing else up far front. Hopefully, I can balance with the servos under the front portion of the cocpit floor. I'd like them to be accessible, since the wings will be permanently mounted. The main wing struts have .018 carbon fiber struts glued into recesses, so that they are flush. All other struts are cf laminated for strength. Not using the Guillows wheels, as they are too heavy. I'm thinking about gluing paper hubs in the micro spoke wheel centers, to make them look more scale. The curvy spoke wheels look corny on scale planes.
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