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



Posts: 1242
Joined: 1/2/2003
From: Planet Earth, IA, USA
Status: offline 		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


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       Post #: 51

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



Posts: 4995
Joined: 7/21/2005
From: Greensboro, NC, USA
Status: offline 		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.



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



Posts: 2931
Joined: 5/25/2004
From: _ , USA
Status: offline 		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.

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       Post #: 53

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



Posts: 4995
Joined: 7/21/2005
From: Greensboro, NC, USA
Status: offline 		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.

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       Post #: 54

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


 

Posts: 628
Joined: 3/9/2002
From: East Berlin, PA, USA
Status: offline 		Here is a retract template that will fit Rhom and Spring air mains.

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       Post #: 55

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



Posts: 7623
Joined: 1/31/2002
From: Ringgold, GA, USA
Status: offline
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.



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       Post #: 56

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



Posts: 4995
Joined: 7/21/2005
From: Greensboro, NC, USA
Status: offline 		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.

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       Post #: 57

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



Posts: 7623
Joined: 1/31/2002
From: Ringgold, GA, USA
Status: offline
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>



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


 

Posts: 38
Joined: 11/24/2005
From: Clyo, GA, USA
Status: offline 		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

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



Posts: 4995
Joined: 7/21/2005
From: Greensboro, NC, USA
Status: offline 		Dave, here you go:

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


 

Posts: 38
Joined: 11/24/2005
From: Clyo, GA, USA
Status: offline 		Thank You very much Rainedav:
I will post a pic in the future, when it's done if yall want.
DAVE

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



Posts: 4995
Joined: 7/21/2005
From: Greensboro, NC, USA
Status: offline 		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.

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