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

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jlkonn -> RE: Bridi UFO Build (all wood) (4/5/2006 1:11:35 PM)

Raindav,
My only experience with trike retracts was in a Phoenix 6 back in the mid 80's.
The brand I used were Rohm (sp?) and the nose wheel was firewall mount.
My feeling is that the firewall mount was lighter since it used a pre-existing structure while the belly mount required add'l ply, etc.
I also had the feeling that the firewall mount was less durable due to the greater transmission of engine vibration directly to the nose gear assembly. The Rohm I used had an aluminum block that the steel gear leg attached to. Over time with oil from the fuel, grit and grim that inevitably worked their way in, the block would wallow out as well as was a source of that black ooze from metal wearing. I always had the feeling that a belly mount would have helped this.
All this may have been a problem unique to my plane.
I know I flew the heck out of it.
I bought Red Max 5% by the 55 gallon drum and flew whenever I could...sometimes everyday...sometimes a gallon a session. I was young, single, working shift in a chemical plant on the Gulf Coast of Texas and spent a heck of a lot of time at the field!
JLK



rainedave -> RE: Bridi UFO Build (all wood) (4/5/2006 10:46:27 PM)

Thanks for the info, both of you.

I've decided to go with the firewall mount to keep things simple. Less ply, less epoxy, less weight.

I added the block to cover the blind nuts. Being 3/4" thick at the bottom there is now plenty of suface area for epoxy.




8178 -> RE: Bridi UFO Build (all wood) (4/5/2006 11:18:00 PM)

The 4-40 bind nuts for the nose gear are pretty small and you should be able to countersink them on the front of the firewall.



rainedave -> RE: Bridi UFO Build (all wood) (4/10/2006 3:03:11 AM)

Tonight I did some work on the retract mounting structure in the wings. Some of you may think I went a bit overboard, but I want a mount that is strong enough to handle grass fields as well as hard landings. I cut eight 1/8" lite-ply rib doublers that extend from the spars back to the TE. I sandwiched ribs #4 and #5 with these doublers with epoxy. I added some extra epoxy where the doublers fit against the spars and the TE.

I then cut two 1/4" aircraft-ply plates that will fit flush in the notches in the ribs. After I get my retracts, these plates will be cut out to accept the retracts and then epoxied into place. The plates are perpendicular to the root of the wing, and are not parallel to the spars or the TE. The whole structure is very rigid and strong.



Paternguy -> RE: Bridi UFO Build (all wood) (4/10/2006 11:29:33 AM)

Here is a retract template that will fit Rhom and Spring air mains.



Ed Cregger -> RE: Bridi UFO Build (all wood) (4/10/2006 5:56:26 PM)


quote:

ORIGINAL: jlkonn

Raindav,
My only experience with trike retracts was in a Phoenix 6 back in the mid 80's.
The brand I used were Rohm (sp?) and the nose wheel was firewall mount.
My feeling is that the firewall mount was lighter since it used a pre-existing structure while the belly mount required add'l ply, etc.
I also had the feeling that the firewall mount was less durable due to the greater transmission of engine vibration directly to the nose gear assembly. The Rohm I used had an aluminum block that the steel gear leg attached to. Over time with oil from the fuel, grit and grim that inevitably worked their way in, the block would wallow out as well as was a source of that black ooze from metal wearing. I always had the feeling that a belly mount would have helped this.
All this may have been a problem unique to my plane.
I know I flew the heck out of it.
I bought Red Max 5% by the 55 gallon drum and flew whenever I could...sometimes everyday...sometimes a gallon a session. I was young, single, working shift in a chemical plant on the Gulf Coast of Texas and spent a heck of a lot of time at the field!
JLK



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


I used trike Rhoms too. I began with the firewall mount and ended up with the belly mount - more room for the fuel tank. Never a problem with the Rhoms working reliably.



rainedave -> RE: Bridi UFO Build (all wood) (4/13/2006 4:33:00 AM)

Thanks for the template, Paternguy. Since I haven't glued the plates in yet, I will be able to cut them easily on the scroll saw. I've decided to splurge and get the Spring Airs. I'm psyched!

Ed, I saw a set of Rhoms on eBay. Maybe it's just the picture but they look like something from the Age of Steam; all that brass.
http://cgi.ebay.com/ROM-AIR-Vintage-3-Gear-Retracts_W0QQitemZ6050062818QQcategoryZ34056QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

I spent more time on this next step than on any other part of the build so far. I've tack-glued the stab into the fuselage. I measued and measured and measured some more. Then I walked away, cleared my head, came back and measured some more. I wanted to make absolutely certain that the stab is square, level and at 0 degrees incidence. I marked the center of the LE and TE and marked a centerline on the fuse at 0 degrees. I cut the stab slots a bit oversize so that I could adjust and shim the stab as necessary to get it true. I have to say, I really took my time with this step and measured dozens of times.

With the fuselage pinned down upsidedown (the top block is flat and parallel to the stab line) I used little pieces of TE stock as wedges that I pressed into the slot to hold the stab in place similar to the way that you would hang a window or a door. When I had the stab set at 0 degrees I then measured the height of the tips from the board. It took a lot of adjusting, but I got it within less than a 1/32" at each place I measured. It would have been a lot easier with a flat stab, but the symmetrical airfoil and the anhedral made it extra tricky. If I had access to a table saw I would have built a ply box that would support the fuse and stab in perfect alignment, but the shimming method worked fine.

The next step will be to fill the small gaps along the slot with wood and epoxy. Later I will add fillets and glass the whole thing.

The pics are poor quality due to lighting issues, but you can get an idea of what it looks like upside-down.



Ed Cregger -> RE: Bridi UFO Build (all wood) (4/14/2006 7:15:50 AM)


quote:

ORIGINAL: rainedav

Thanks for the template, Paternguy. Since I haven't glued the plates in yet, I will be able to cut them easily on the scroll saw. I've decided to splurge and get the Spring Airs. I'm psyched!

Ed, I saw a set of Rhoms on eBay. Maybe it's just the picture but they look like something from the Age of Steam; all that brass.
http://cgi.ebay.com/ROM-AIR-Vintage-3-Gear-Retracts_W0QQitemZ6050062818QQcategoryZ34056QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

I spent more time on this next step than on any other part of the build so far. I've tack-glued the stab into the fuselage. I measued and measured and measured some more. Then I walked away, cleared my head, came back and measured some more. I wanted to make absolutely certain that the stab is square, level and at 0 degrees incidence. I marked the center of the LE and TE and marked a centerline on the fuse at 0 degrees. I cut the stab slots a bit oversize so that I could adjust and shim the stab as necessary to get it true. I have to say, I really took my time with this step and measured dozens of times.

With the fuselage pinned down upsidedown (the top block is flat and parallel to the stab line) I used little pieces of TE stock as wedges that I pressed into the slot to hold the stab in place similar to the way that you would hang a window or a door. When I had the stab set at 0 degrees I then measured the height of the tips from the board. It took a lot of adjusting, but I got it within less than a 1/32" at each place I measured. It would have been a lot easier with a flat stab, but the symmetrical airfoil and the anhedral made it extra tricky. If I had access to a table saw I would have built a ply box that would support the fuse and stab in perfect alignment, but the shimming method worked fine.

The next step will be to fill the small gaps along the slot with wood and epoxy. Later I will add fillets and glass the whole thing.

The pics are poor quality due to lighting issues, but you can get an idea of what it looks like upside-down.



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


I just got back from the listing you posted. No wonder you think they are from the Age of Steam!

The color balance is off. It looks as though someone is shooting outdoor film (blue balanced for sunlight) in the presence of filament/incandescent light bulbs (orange biased light).

Believe me, the originals were equipped with black metal frames, bare aluminum blocks, conventional 5/32 music wire struts and a couple pieces of white nylon. They did NOT look like that. <G>



oldpatflr -> RE: Bridi UFO Build (all wood) (4/21/2006 5:56:50 PM)

Hi Guys;
My name is Dave, user name oldpatlflr. Have not built or flown since 1989, but have restarted this year. Am building a UFO, foam wings and wood fuse, tail dragger, Rohms in the wing. I don't know whose kit it is, got it cause somebody shot down my Dirty Birdy about 1982. Anyway, could anybody tell me where the CG should be, and where it would fly the best. Just glue the stab on this morning and it's scary, cause this is the straightest airplane I've ever built! Am flying now a Sterling Ringmaster trainer, flattened out the wings, just to make it fly better, to learn again to land, and a Sig Kougar with an old OS Max 60H. Flys great just like all my other ones. Anyway. Flew my old UFO to 17th place at the 83 Nats. It's still alive in my attic and maybe someday will dust it off and have at it. Sorry if I'm long winded, but I LOVE model airplanes.
Thanx
DAVE AMA 39847



rainedave -> RE: Bridi UFO Build (all wood) (4/21/2006 6:21:56 PM)

Dave, here you go:



oldpatflr -> RE: Bridi UFO Build (all wood) (4/21/2006 9:29:24 PM)

Thank You very much Rainedav:
I will post a pic in the future, when it's done if yall want.
DAVE



rainedave -> RE: Bridi UFO Build (all wood) (5/6/2006 3:11:59 AM)

Well, I finally got my retracts. It's a long story, but now I can resume building. I went with the rail mount nose unit, it just gives better clearance than the firewall option. I'm going to use a Hayes Slimline 12oz tank. It has the lowest height I could find in that size.

These are the new spring-down Robart 510 series. They look to be very well made; all metal, no plastic. The mains have 3/16" wire and the nose is 5/32". I can't see how Robart saves anything doing this, but you have to get the hook-up instructions and the mounting templates from their web site. Anyone without internet access would be in a fix. Another nice thing to have would be a quick disconnect for the wing units. I'll pick one of these up at my LHS this weekend.

This is the first set of retracts I've ever owned, so I'll probably have some questions along the way.



Paternguy -> RE: Bridi UFO Build (all wood) (5/6/2006 3:40:01 AM)

Did you ever decide on a canopy ?



rainedave -> RE: Bridi UFO Build (all wood) (5/6/2006 4:11:03 AM)

Paternguy, no I haven't. I'm still tossing around the idea of carving one from balsa and hollowing it out. Since the whole fuse is going to be glassed and painted it would work. Plus, I could incorporate those odd tunnels down the canopy sides if I carved one.

BTW, I just got a great deal on a compressor at Sears. 3 gallon/1hp for $90 (normally $125) and a very low CFM touch-up gun at Harbor Freight for $10. Since I'll be painting the fuse, I've decided to use Koverall on the wings (they have open framework) and paint them, too.

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00915310000&subcat=Air+Compressors+%26+Inflators



rainedave -> RE: Bridi UFO Build (all wood) (5/15/2006 3:43:16 AM)

It's been a while since an update, I just haven't made much progress lately. Here is a pic of the nosegar setup. I still have to cut away the ply mounts for wheel and wire clearance. This thing is going to sit pretty low to the ground. I've calculated that I'll have about 1 3/8" to 1 1/2" clearance with an 11" prop. So, I may be hand-launching! Ha! There's a 3/4" block of balsa that will be attached over the nosegear area and, of course, be cut out for the gear to retract. If you look at the pic you can see how it will mate up with the chin block that's already in place. Later, a center section will be built onto the bottom of the wing to meet up with said block. The Hayes Slimline 12oz tank fits like it was molded for this design. And because the top is beveled it sits high enough to be on center with the spraybar.

One thing I'm learning is that a lot of these specialized competition planes were designed to use equally specialized hardware. An example is the elevator hookup. I'll either need to fabricate a Y-linkage or shell out $20 for one like Central Hobbies sells. Almost every piece of hardware I've used so far I've had to measure and calculate before buying.

Nosegear retracts are new for me. I'm thinking about either using some heavy monofilament or small braided cable to hook up the tiller arm. My plan is to attach these two lengths of cable to a second tiller inside the fuse. That one would then connect to the rudder servo via a single standard flexible pushrod. The cables would go stack upon retract, but the pushrod would remain stationary since the second tiller would be hard mounted. This seems easier to adjust that trying to run both cables all the way to the servo. Any feedback/advice would be great on this issue.

The last two pics reveal how much wood was lost to get the engine in and out. But, looking at the photos of the original in the RCM article indicate that it had a pretty large opening, too.



rainedave -> RE: Bridi UFO Build (all wood) (5/21/2006 4:39:35 AM)

I went ahead and ordered the Great Planes canopy that I'm pretty sure was originally produced for their Dirty Birdy kit. It's a bit shorter than the outline on the UFO plans, but is of the same contour. I doubt anyone will ever spot the difference in length. I also ordered a pull-pull rudder set which I may or may not use. I'm thinking I'll solder together a split elevator pushrod. MK makes a funky bellcrank thing that looks interesting, but would require a service hatch in the fuse.

Tomorrow I'm going to join the wing halves so I can rest the fuselage on them and measure and cut the main retract gear to length. Since the top of the fuselage is a flat slab (I haven't carved it yet) I can just lay a spirit level on it both longitudinally and laterally to get things level. Then, I'll be able to construct the wheel wells. This, I'm looking forward to. I'll soak some 1/32" sheet with amonia and laminate them cross-grained around a cylindrical form with yellow glue. I've been spending a lot of time lately tinkering with and planning out various hardware so it will be nice to start making some balsa dust again.

The nosegear has been measured and cut. I'll actually get more ground clearance than I though I would, about 7" from the center of the prop shaft to the table, so, that's 1 1/2" clearance with an 11" prop give or take.



rainedave -> RE: Bridi UFO Build (all wood) (5/23/2006 2:51:18 AM)

This can't be. It's actually starting to look like an airplane.

I've finally made it through what was a real impass for me and this project. It was one of those steps where you can't proceed until it's done, but certain steps have to be finished first in order to do it. I couldn't measure the gear legs to cut them until the plane was at a point where the fuselage could rest on the wing. And I couldn't make the wheel wells and finish the wing until the gear legs were cut.

Glueing the wing halves together was more complicated than usual. My dad had an old 8x4 plywood table, so I cut out two cradles to fit under the tip ribs and raise the halves to the correct dihedral. I glued them to the table along with a third cradle to support the center of the wing's LE and TE. These supports held the wing halves at 0 degrees incidence over the table with the tips at the correct height (1 5/8). I didn't want to accidentally glue in any washin or washout, so I worked carefully to make sure everything was true. I spent more time setting everything up than I did glueing, but I'm pretty certain that the wing panels have a constant incidence from tip to center to tip.

Then I temporarily installed the retracts and placed a board across a narrow table that was just wide enough to support the tires with the excess gear wire extending down over the sides. Using a spirit level I adjusted the main gear until things were level (the nose gear can't really be adjusted since it has to be as long as possible and still fit in the fuselage). Then I cut the wire and filed them smooth. The next step is to build the wheel wells and finish sheeting the center section of the wing. After that I'll install the pushrods, sheet the bottom of the fuse and start planing, carving and sanding. I might need to buy a shop vac for that stage.



Jagdgeschwader 26 -> RE: Bridi UFO Build (all wood) (5/23/2006 4:00:57 AM)

Rainedav: You are one heckuva builder.

I'm not worthy. I'm not worthy.

To ask a dumb question: what kind of glue are you using? I don't see any CA bleed on the sheeting. My guess is you are using aliphatic (i.e., Titebond). Your stab building tips are a big help. I hate building built-up symmetrical stabs and vertical fins. I always take easy way out and cut foam cores and sheet them. Now you've given me the answer. Thanks!

The care you've taken with aligning and squaring up everything indicates you are far above the average builder. Thank you for sharing this build. I am learning a lot still, after 50+ years in the hobby.

Your workmanship reminds me of that of the late Barney Lipold from the Detroit area. He was a retired pattern maker, and after suffering a stroke and the loss of the use of one hand, he still built with the same degree of excellence you demonstrate. You have my utmost respect.

Keep up the excellent work. This is a great thread. I am looking forward to reading more.

later,



8178 -> RE: Bridi UFO Build (all wood) (5/23/2006 12:50:11 PM)

Excellent work Rainedav! It is a rush when you finally get the beast far enough together that it can sit on its gear. Next you’ll need to put some jack stands under her and start drop checking the landing gear.



rainedave -> RE: Bridi UFO Build (all wood) (5/24/2006 3:28:36 PM)

Wow, thanks for the compliments. I hardly feel worthy of them. Two good things about these RCU build threads is that we share ideas and techniques and that the scrutiny of others makes you build with more attention to detail. I've learned a lot over the past few months by hanging out here, and it's great getting suggestions and feedback.

Al, the stab method of using the notched ribs was on the plans, I just modified it to make it easier by laminating the LE and TE pieces. I've been using Elmer's wood glue, CA and epoxy depending on the task. I did use wood glue on some of the sheeting since I needed to move it around to line it up.

I've made the wheel wells for the retracts. It was a lot of fun. I laminated three layers of 1/32" balsa around a can of Endust which was the right diameter. I sprayed the strips with Windex (amonia) and coated them with yellow wood glue, then used tape and rubber bands to hold them around the can. Then I drew circles on a sheet of 3/32" balsa and ca'd the wells to that outline. After razor sawing the opening for the gear legs I glued on the side pieces. They came out very light and strong. I won't glue them into the wings until I have the wing bolts mounted and the wing saddle fine tuned. Then I'll re-adjust the wheels again to make sure the plane is level and glue in the wells.



rainedave -> RE: Bridi UFO Build (all wood) (5/30/2006 9:57:00 PM)

I got the gear mounts epoxied in place. Tonight I'll try to install the wheel wells in the wings and cut and attach the bottom block to the fuselage.



rainedave -> RE: Bridi UFO Build (all wood) (6/1/2006 2:00:13 AM)

Well, if I keep doing a little bit each day I'll eventually finish! Tonight I shaped and rough sanded the chin block. I cut out the opening for the nose gear while it was still a rectangular block, then tack glued it to the fuselage and went to work with the razor plane. It's just one of those old el-cheapo X-acto block planes, but if you take some time to hone the blade on a stone you can get it very sharp. The trick is to only have a very minute portion of the blade extend out of the plane; I'm talking like a 1/4 of a millimeter or less. Any more and it will gouge or tear the wood.



8178 -> RE: Bridi UFO Build (all wood) (6/1/2006 2:11:46 AM)

Try holding the plane at a 45 degree angle to the cut direction. The old time blue blades worked the best but I haven’t seen any of them for a long time.



JimTrainor -> RE: Bridi UFO Build (all wood) (6/1/2006 2:29:55 AM)

I have the same compressor and similar paint gun. It works fine (or at least well enough for me). Probably not a heathly duty cycle for the compressor... but for occasional use it doesn't really matter too juch.

The next time I use it I plan try a small HLVP touch up gun like this: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=90978



rainedave -> RE: Bridi UFO Build (all wood) (6/1/2006 2:54:02 AM)

8178, that's exactly what I do, so that the blade slices through the wood, same principle as a guillotine blade.

I called my X-acto plane a block plane, but it's really what they call a smoothing or finish plane with a blade, or iron, at 45°. The main problem with a block plane is that it's designed to cut end grain on butcher blocks, hence the name. The blade is at too shallow of an angle for shaping balsa, closer to 20° or even less.

This site sells what looks like a nice smoothing plane with a Japanese iron for a mere $265:
http://www.knight-toolworks.com/wooden.htm#Coffin



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