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Joined: 7/3/2003 From: newton,
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Hi, guys, just got back from my club meeting. Rich, you're looking good, really making progress. I won't take bets on who finishes first between the three of us. Your cowl is very nice, I like the idea of using the tubing for your hinge lines.
Chic, I'm not sure about the rockets yet. I'll probably use styrene tubing for the tubes at least, but I'm not worrying about "accessories" just yet. As far as the aileron linkages go, here's the down and dirty design. The issue is clearing the hardwood stick at the bottom of the trailing edge, because the control arm must be as far toward the bottom of the aileron as possible for adequate leverage. I think I can accomplish the clearance by running the rod off at the top of the servo to increase the angle, and by maybe making a small bend where the arm passes through the T.E. of the wing. As big as the ailerons are, I don't think we'll need a lot of travel, and it will be "pushing" the aileron 'up' more than it will be "pulling" 'down', with the appropriate amount of differential.
I may still have to trim the bottom strip a little, but I figure the rod won't have to travel more than 1/2-5/8" back to raise the aileron, and even less to lower it.. I'm using Hitec 645MG on all control surfaces, so no problem with servo power.
For a prop, I have a Dynathrust 22-8. Contrary to what I have heard about these props, I have had good results and like them, wish I could find a couple of spares for this plane. I have a 20-8 that I use on my Nosen Trainer (with a US-41).
< Message edited by khodges -- 6/13/2008 4:33:36 AM >
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Club Saito #2, WACO Brotherhood #20. What other trouble can I get into?
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Aileron servo mounts are done. I tried to be as simple as possible, but keep them secure, and still be able to remove them if necessary. I made a small tray to mount the servo in, and the tray screws to two crossmembers that fit in notches cut in the rib top edge. The crossmembers have 2-56 blind nuts sunk flush with the top surface. I also laminated the bay side of R10 and R11 with 1/64 ply from the T.E to the spar to stiffen and strengthen them. The crossmembers will fit against the top sheeting of the wing, so I cut the screws that hold the servo tray to the crossmembers so that they don't protrude. I will add a couple more crossmembers a bit further apart on the bottom edge of the ribs to fasten a hatch cover to.
The trays are made from two blocks of 1/2x1/4" basswood, 3/32 hobby ply, and 1/32 hobby ply. The crossmembers are made from 1/2x1/4 basswood.
The bottom back corner of the servo just clears the inside, meaning that it almost protrudes proud of the bottom of the ribs. Rich, if you do something similar, you'll have to go closer to the spar with your servo so it will fit between top and bottom of the ribs. If you decide to use a standard under-the-wing linkage, you can just mount the servo to the hatch cover and have the arm protrude through a slot in the cover.
I'll use this same method for the flap servos. I guess the next step is to start building flaps and ailerons.
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Club Saito #2, WACO Brotherhood #20. What other trouble can I get into?
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1/5 Dawg Chic: Thanks for the pic's and measurements, just what I needed.
Re-did the tail wheel, now I have the right angle to the stirrup. Compare post #310. Bent from 1/6 brass and spring plate on top of that and brass tube for screw and pivot point. All soldered together. Clob of Epoxy putty on top around bolt and small I hook and a little shaping. Arnold has a buff passenger!!
Ken: Your really going to town on your build. Go man Go! Out standing ideas and changes.
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1/5 Dawg
Got the control horn on the rudder and string in place so can sheet that now. Wing strut fuse mount in, think I can finish up the botton fuse sheeting now. Next week I should be ready to start the wing. At least laying things out for study!
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quote:
ORIGINAL: RICMOD5634
Arnold has a buff passenger!!
would she be the "Barbinator" ?
Looks like the slipstream was a bit much for her wardrobe. This IS a family site, you know.
Rich, you're the one going to town, it's really looking good. Take your time on the wings. It might be worth the time to make a jig like the one I borrowed. It would take out a bit of fiddle factor.
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Club Saito #2, WACO Brotherhood #20. What other trouble can I get into?
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1/5 Dawg
Ken: Are those 3 separate blocks with Rib cradle in each one, for R-1 / R-7 / R-15 . Screw in front at L.E. for setting C.L. at 0° ? Is there nothing at the T.E.? Can’t see cradle for R-15. How is the Incidence set? Are they just set over plans to maintain correct wing angle? See Fig. 1
My thought is for Block at R-15 to have two added screws running clear through the block so they would contact the table top. One each at F. and R. of block. These could be screwed down to give the block 5/32 (As per my plan)off the table to set the Dihedral from R-7 to R-15. Then continue to screw rear screw to give you 11/32 (my figure ???) at the T.E. for 1.5° of Incidence at the rear of the block from the table top. See Fig. 2
Does this make sense !!!!!!! Or can you describe how the jig is laid out and give me a pic. of each.
Sorry about the pic, just trying grandchildrens dolls to see how they compared for size. Didn’t think of family channel.
Chic: Was just running through pic’s and saw the one of the Cabin Top Windows and the million screws. How in the world do you mount the wing or get into the cabin?
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1/5 Dawg
Using Roy's Washout explanation and Fig 3 sine 1.5 deg = .0262 If the cord (of Rib R-15) is 6 3/4 (6.75), would the delta be 3/16. Would the Delta be add from C.L. of R-15, plus dihedral? Rich
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I thought the dolls were hilarious. I think Arnold is robbing the cradle, though, he's much bigger than Barbie
The wing jig is three separate pieces. The one that fits under R1 is identical to the one at R7. This portion of the wing is constant chord and is "straight", has no washout. The piece at R15 is shimmed 3/16" higher (the amount the wing rises from R7 to R15) and the cradle for the rib is cut so the rib sits in it with the T.E. raised 1.5 degrees relative to R7. You'll need to mark the chord lines on each rib when you set up the wing (they are shown on the template page of the plans).
My friend made the jig from 3/4" thick x 1" and 2" pine planking, like you can get at any builders store. He traced a template for R1, R7 and R15 and cut the cradles to follow the outside of the rib, a "negative" sort of. When he traced R15, he placed the template with the T.E. 1.5 degrees off parallel to the bottom edge of the stick he cut the "negative" from. When it is screwed to the jig base, the washout is set if the piece is flat on the table like the other pieces are. The large screw on the R1/R7 pieces is a "bumper" for the L.E. block, so the ribs sit properly in the cradles.
Pics below: 1st pic, bottom one is R1/R7 (each is same), and the top one is R15, 2nd pic, R7 sitting on top of R15 (my camera alignment is off, the spar marks should align), but you can see how R15 is raised and how the washout "lifts" the T.E. of R15. 3rd pic shows part of the plans that show the 3/16 elevation of the wingtip (it's called 'dihedral angle' on the plans, but that is a different animal from the wing dihedral as mounted to the fuse).
When you start throwing math at me more complicated than 2+2 and nought gozinta nought, I start running for cover. Sines, cosines, tangents and the like make me cringe. (I flunked trig in H.S., but got "A's" in geometry, go figure). I know 'delta' is the change between values, but that's about it.
Basically, if you measure the thickness of R7 at the spar (thickest point) and then measure R15 at the spar, half the difference is the needed rise from the table of the wingtip at that point (spar). The T.E. of the tip will rise an additional mount from the incidence change of the washout (1.5 degrees). I measured the washout on R11 as half of the washout at R15 (it's halfway between R7 and R15) When I laid out my ribs, I glued R7, R11 and R15 first, with the washouts set. then I dry-fit the 1/4x1/4 stick at the L.E. and placed the remainder of the ribs between R7 and R15, and this stick set their respective washout angles. Of course, I did this with the bottom main spar stick flat on the board, and not in the jig, since I had already built one of my wing halves before I received the wing jig. However, the jig verified that my wing was correct, as it fit perfectly in the jig.
I'm thinking that with your plane being a smaller scale, the cross-section of the wing at comparable points would be thinner than mine, if only by 3/32 or 1/8" or so. What does your plan show at the front view of the wingtip (like the pic I posted )?
< Message edited by khodges -- 6/14/2008 10:44:08 PM >
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Club Saito #2, WACO Brotherhood #20. What other trouble can I get into?
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Question again on flap servos. since they have to operate together, instead of opposite, what's the best way to set them up? Mount them so they move together, or mount them like aileron servos and use a reverser on one of them? The other method would be to make the linkage operate from the "top" on one side, and the "bottom" on the other, but my mount won't permit that in my case. Another way would be to mix two channels on the Tx and reverse a servo via the radio. (if you have enough channels on the radio)
What are your ideas, recommendations?
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Club Saito #2, WACO Brotherhood #20. What other trouble can I get into?
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1/5 Dawg
Ken: Thanks for explaining the jig set up, seems pretty simple. Something I can do, if I can get my math checked. My wife works with an engineer, so will send him Roy's washout sheets and my figures, and see if he comes up with the same numbers. My dihedral angle is 5/32, 1/32 less than yours. My figure is 3/16 rise at the rear of R-15 to set the incidence, what is your measurement? As to the flap servo's looking at the plans, the control rods do not exit at the same place on the wing. Which would not give you the scale appearance You'd be looking for. I would think that a mixing two channels on the Tx and reverseing one would be the way to go. Me, I'll just go with the plans and exit at different spots. I like your idea of angleing the T.E. of the wing at the flap for scale appearance. You don't think this will make any differance in the fly of the model. Rich PS Was going flying tomarrow, but looks like more rain moving in and winds around 25mph. So I guess it's Dawg time.
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1/5 Dawg
Ken: Have you mounted your H Stab and fin, or are you waiting to get the wings on to get better allignement. Do you mount these before you glass. With monocoat you cover before they are mounted, leaveing bare would where they will be glued.
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Joined: 7/3/2003 From: newton,
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Rich, I didn't measure the rise at the T.E. of R15. All I see is that the chord line is 1.5 degrees offset from the chord at R7, so I know it's there (washout).
I decided to set the flaps up symmetrical and reverse one of them using the Tx. I had planned to use a 7 channel Rx, so that gives me just enough to work with. I may just use one channel for ailerons, instead of two. I can set up differential in the linkage at the servo horn, and use two channels for the flaps, and still have a free channel for something else, such as a bomb drop.
I'm concealing both flap and aileron linkages, so it wouldn't matter about them exiting at different places. I haven't mounted the tail surfaces yet, I'll mount them just before finishing, a
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RE: 25% Cessna L-19/0-1 Bird Dog build - 
