RE: Bridi UFO Build (all wood) (Full Version)

All Forums >> [RC Airplanes] >> Pattern Flying >> Classic Pattern Flying



Message

rainedave -> RE: Bridi UFO Build (all wood) (6/16/2006 4:30:25 AM)

The elevator pushrod and the pull-pull linkages are more or less done. I need to buy a couple of larger servo arms, mainly so that the cables will be parallel. With that Futaba wheel each cable is about 1/4" too far in to be equal to the width of the rudder horns. The throttle servo is installed, but I still need to put in the retract servo which will go right across from the elevator servo. Thanks again Paternguy for suggesting the Dave Brown elevator pushrod, I mean there is absolutely zero play in that setup.

I'm sure there are several ways to do this stuff. I guess some people glass everything before installing the control hardware. What I'm going to do is leave the plastic flexrods exit guides extending out of the fuselage a couple of inches or so and cover up the ends and cable connectors with tape. Then after everything is glassed I'll cut the flexrods flush with the fuselage sides and everything will already be in place. You've probably seen C/L models being painted with the leads hanging out and taped up; same principle. I don't think I would ever be able to take everything out and then fish it back through again. I don't even want to think about trying to do that.

The next thing to do is glue on the bottom cross-grain planking, sand off the corners and start getting it ready to glass.



rainedave -> RE: Bridi UFO Build (all wood) (6/18/2006 1:55:35 AM)

I glued on the bottom planking and attached the subfin today. I'll add some pics a bit later.

Neither the plans nor the RCM construction article mention a thing about recommended control throws. I asked 8178 for some help and he gave me the throws for his Tipo and Blue Angel. By measuring the width of my control surfaces and using a protractor I was able to figure out a range of degrees that I think will work as a starting point for high rates. Of course, setting up differential would mean different degrees up and down, but the figures below are for total throws. There's also the issue of different surface widths on the various planes that throw the figures off a bit. Still, I think I have a good idea now of where to start.

8° each way for aileron = 3/8" total; which is the same as the Tipo
13° each way = 5/8" total; equals the Blue Angel
So, 10° each way is between the two at 7/16" total throw which is what I'll start with for high rates.

10° each way for elevator is 3/4" total; same as Tipo
18° is 1 3/8" total; equals the BA
15° is 1 1/8" total, again I'll use that for initial HRs.

18° each way equals 2 3/4" total rudder; same as BA
20° gives 3" total, sama as Tipo
Either one of these settings should be fine to start with.

I'd also like to hear from you all flying Dirty Birdies as to what throws you're using since the UFO is very similar. Thanks.



Paternguy -> RE: Bridi UFO Build (all wood) (6/18/2006 3:40:21 PM)

I have a glass UFO kit in the basemant, I will look and see if the control throws are in the assembly manual, this evening.



FSFLYER -> RE: Bridi UFO Build (all wood) (6/18/2006 5:35:34 PM)

I just looked at the plans for the glass UFO kit that I have. It doesn't show any throws, in fact the information is rather sparse, all that came with it was one sheet, 15" x 30". Not much information, but plenty to get the glass/foam version done. They do show an all up weight of 8-1/4lbs. Did you get any more information with your glass kit? Also, they include 3/32 sheeting and fixed tri-gear. Going to substitute 1/16 sheeting & add retracts when I finally get around to building it.



rainedave -> RE: Bridi UFO Build (all wood) (6/18/2006 9:04:37 PM)

Thanks y'all for checking the glass instructions. The UFO's control surface widths are very close to those of the Tipo, thanks again 8178. So that serves as the best guide:

Aileron: Tipo - 1.375"; UFO - 1.3125" (1 5/16)
Elevator: Tipo - 2.125"; UFO - 2.125"
Rudder (widest point): Tipo - 4.125"; UFO (average width) - 4.5"

So, I think 8° for ailerons - same as Tipo - will be good; 10° for elevator - same as Tipo; and 20° for rudder - which is just a bit more than the Tipo at 3.125" total throw.



rainedave -> RE: Bridi UFO Build (all wood) (6/20/2006 2:39:59 AM)

There's an issue with wooden fuselages that are rounded on the four corners and have a sheet balsa top, bottom and sides. The taller the sides are, the easier it is to have it develop. It seems to happen because of two things: one, because there is extra wood in the form of stringers along with glue in the corners, and these stringers are usually of harder balsa; and two, the sheet sides, depending on how thin they are sometimes have a tendency to bow inward. I think this bowing is caused by the various pressures and tensions in the fuselage structure, but I'm not an engineer.

At any rate, if you're not careful you can get a fuselage cross section that looks like the drawing on the left when what you want should resemble the right drawing. The concave problem seems to get magnified when light and shadow hit the fuse at certain angles. Glossy paint will magnify the effect even more, so it only takes the slightest bit of concave surface to become visible.

I've worked really hard with the razor plane and sanding blocks to get the UFO fuse to look like the drawing on the right. But, there's a fine line between getting the corners shaped correctly and going too far and getting the wood too thin. The best fix is to add extra stringers that allow you to plane down the sides of the corners further without things getting too thin, leaving the middle area of the sides the thickest. I'll get some pictures up a bit later.

Of course, a glass fuse eliminates the problem all together!



rainedave -> RE: Bridi UFO Build (all wood) (6/20/2006 3:31:51 AM)

Here are some pics that attempt to show the outward or convex curve to the fuselage sides that I'm after. You can just see me special sanding trousers, mates.

The surfaces don't show up well in the photos, but the joint near the tail where the two side sheets meet gives a good image of the rounded look.

I've got everything masked off with tape like pushrods, connectors and servo rails (I'm sure to drip resin inside the fuse), I just need to clean off the dust and I can start glassing the thing.



8178 -> RE: Bridi UFO Build (all wood) (6/20/2006 1:01:35 PM)

Looking great! Another solution is to use 1/2“ triangle stock in the corners to provide a larger radius. The triangle also acts as a cutting guide as the corner is rounded down with the razor plane because the glue joints can be faintly seen.

Looking forward to seeing your glassing process.



Paternguy -> RE: Bridi UFO Build (all wood) (6/21/2006 2:02:33 AM)

rainedav,

You have inspired me, I went down to the basment earlier and pulled out my UFO kit. I am going to finaly finish it. LOL

I ordered a new wing from Dynamic Balsa, the original cores got damaged in my last move. The glass fuse is in great shape. I forgot how good the glass work on the old Bridi kits was. The fuse is actulay pretty far along, I need to mount the firewall and the nose gear, and of course build the wing.

Thanks,
Doug



rainedave -> RE: Bridi UFO Build (all wood) (6/21/2006 4:01:54 AM)

That's really cool Doug. I've never seen a glass UFO so you'll have to post some pics.

Thanks 8178! 1/2" tri-stock is a great solution, even better than the extra stringers.

I'll probably start the glassing on Saturday. I still need to pick up a few things like some alcohol for cleaning up, a soft brush for smoothing out the glass cloth before pouring on the resin (it always snags and pulls on my fingeritps for some reason), and some mixing cups. I'm using Pacer Z-Poxy finishing resin which I've used before and liked and 3/4oz cloth. I'll glass the fuse, fin, stab, elevators, rudder, ailerons and the wing out over the gear wells.

I haven't talked about finishing much, but here's what I'm going to do. The outer, open sections of the wing will be covered with nitrate dope and SIG Koverall. I went with Brodak primer and dope so after the Koverall is filled with nitrate and shrunk tight the entire plane, fuse and all, will get primed with the Brodak primer. I'll use this to fill the glass instead of extra coats of resin. I have no idea how many coats of primer and putty it will take, but most of it gets sanded off anyway. Then I'll spray the colored dope and finish with clear butyrate. I'm going to keep the color scheme simple; two main colors a little bit of a third color for striping, or whatever.



Paternguy -> RE: Bridi UFO Build (all wood) (6/21/2006 10:23:24 AM)

Try using pantyhose instead of glass cloth on the fuse, its much easier to work with and its lighter. I did this on my DB and it worked out great and it has been very durable. I used CA to tack it down in several places and pulled the slack to the wing sadle as I tacked it in place. Then I used resin to fill in the weave of the nylon.



Paternguy -> RE: Bridi UFO Build (all wood) (6/22/2006 12:08:42 AM)

Here are a couple of pics of the fuse. One is next to my Dirty Birdy fuse, I was trying to show the diferance in size between the 2, The UFO is about 3 inches longer.



rainedave -> RE: Bridi UFO Build (all wood) (6/22/2006 1:39:09 AM)

Thanks Paternguy. I think I'll definitely try the pantyhose method on a future model. I've already invested in the glass cloth and I also need to strength it will add to the slender part of the fuse; it's sanded pretty thin.

Your glass fuse looks awesome. Very sleek. It makes me want to scrap the plastic canopy and carve a hollow balsa one and fair it into the fuse with microballoons. Speaking of microballoons, I still need to make the wing fillets and the fairings around the stab. Mine will get sleeker. In the meantime, here are a few pics.



rainedave -> RE: Bridi UFO Build (all wood) (6/22/2006 3:28:55 PM)

I was thinking about how these '70s pattern planes are referred to as "rocket ships" and I got to thinking about the UFO and how Bridi named his designs. Star Wars, Buck Rogers and Close Encounters were all a big deal at the time. Check out this pepper mill compared to the middle pic in my last post. I think the UFO does hint at science fiction imagery, especially with the teardrop canopy way up front. While I'm on this subject, I always suspected that the name Kaos was borrowed from the evil Kaos organization in Get Smart. Any truth to that?



FLAPSDOWN -> RE: Bridi UFO Build (all wood) (6/23/2006 6:59:19 AM)

Hmm...It's a direct quote...

"It makes me want to scrap the plastic canopy and carve a hollow balsa one and fair it into the fuse"... After seeing the UFO lines of the glass fuse, he thinks there may be an alternative. We'll just have to see.

We eagerly await. Will he..or..won't he. Hey, he might be a scale builder after all.

Bill



FLAPSDOWN -> RE: Bridi UFO Build (all wood) (6/23/2006 7:11:03 AM)

It's all in fun. But when one like rainedav takes the time to build a vintage pattern plane and takes the time to share it with us, it's special. It's also a beautiful build of a successful pattern plane from the late 70's and into the 80's. I ask, doesn't it become a scale project?

Dump the plastic canopy and dust off the xacto.



FLAPSDOWN -> RE: Bridi UFO Build (all wood) (6/23/2006 7:16:21 AM)

I hope I'm not too late. RAINEDAV's probably throwing glass around as we speak. Panty hose is for long legs, in cooler weather. It's summer.



Paternguy -> RE: Bridi UFO Build (all wood) (7/7/2006 3:32:04 PM)

Any new progress on your UFO. I got the firewall and retract mount done on mine. I also have the wings sheeted and the wingtips on. I will post some pics later.

I can't find the instructions for mine. Where is the CG location ?



rainedave -> RE: Bridi UFO Build (all wood) (7/7/2006 6:42:43 PM)

Hey, Paternguy! Look at post #60 on page three of this thread. I uploaded scans of the CG designations as shown on the UFO plans.

I've been fiddling with some other planes lately. I always seem to have three or four things going on at once. I electrified a scaled down Miss Martha I built a few months ago that was originally intended for 1/2A glow (see pic). It's a real blast in the neighborhood softball field!

The truth is I'm just being indecisive about my UFO. I can't decide whether to make the epoxy/microballoon wing fillets and stab fairings before I apply the glass cloth or afterwards. Any advice on which sequence typically works better? I'll be using Pacer epoxy finishing resin for the cloth, so it probably doesn't make any difference what goes on top of the other in terms of compatibility. Plus, we've had nothing but rain, and I don't like working with resins and paint and stuff unless the air is relatively dry - by NC standards, anyway (75% humidity is arid where I live).

Definitely post some pics. Post them in here if you don't want to start a whole new build thread.



Paternguy -> RE: Bridi UFO Build (all wood) (7/7/2006 10:30:58 PM)

When I built the DB I put the glass on first and then the fillets. It turned out pretty well. I just couldn't figure out a good way to get the glass over the fillet. Hope this helps.



Ed Cregger -> RE: Bridi UFO Build (all wood) (7/8/2006 1:36:09 AM)


quote:

ORIGINAL: Paternguy

When I built the DB I put the glass on first and then the fillets. It turned out pretty well. I just couldn't figure out a good way to get the glass over the fillet. Hope this helps.



-------------


You can put the glass over the fillets in strips. It feathers out pretty well.



Paternguy -> RE: Bridi UFO Build (all wood) (7/8/2006 2:58:03 AM)

The other reason I did it that way is I am inherantly lazy, I didn't want to sand the fillets twice. LOL



rainedave -> RE: Bridi UFO Build (all wood) (7/8/2006 3:07:38 AM)

Thanks for the help, both of you.

The more I think about it, the more I like the idea of being able to spread the epoxy/microballoon mixture over existing resin. Since I'll be using my finger and a rounded paddle to smooth the mixture into its concave shape it just seems to make more sense to me, anyway, to blend it in over a glass/resin base than bare wood.

It's time to stop theorizing and just do it.



Paternguy -> RE: Bridi UFO Build (all wood) (7/11/2006 11:35:05 PM)

A couple of pics of the glass UFO I am working on. I am sure 8178 will be thrilled to see she isn't dragging her butt on the ground. LOL



phantom_najd -> RE: Bridi UFO Build (all wood) (8/1/2006 5:04:46 PM)

This is a reply to the post # 81.

I come across your thread along with the building threads of 8178. Man I've just finished scratch building a model called POPPET (53" bi wing) and I just wish I read your threads before I have started. You show a great level of workmanship and unbelievable care for details. I'll make sure to have your thread and some others for 8178 printed out for reference while building the new project. Thank you very much for sharing your build with us!

This is a bit late, I don't know if you still are worried about binding the steering pull-pull cables somewhere when the nose wheel is up or not? Anyways, my idea is that you make a knot in both the cables 1 or 2" from the servo and tigh two rubber bands (one on each cable) then while the nose wheel is retracted stretch the rubber band and fix them to the sides of the fus. By that you'll be sure the cables are under a slight tension during the entire retract sequence.

Azzam



Page: <<   < prev  3 4 [5] 6 7 8 9 10 11 12   next >   >>  

Valid CSS!




SITE MAP!   : :   FORUM RULES

© 2001 - 2007 24-7 RC, LLC, all rights reserved.
0.53125