Redback

How do you get your drill press to make square holes

I'd like to be able to do this with mine!!

Terry

foodstick

I am not sure if I missed it on your thread, but are you building in a big bomb drop setup?

JeffinTD

So, next steps are gluing in the screw plates on the bottom, followed by 6 hardwood gussets, then epoxy on the front and rear sections of the ribs. No pics yet.

I'm thinking about doing something different with the hatch, like I have some Plexiglass I could make a skylight with. Any thoughts about how that would look?

Fastener wise, I was thinking of not using the nylon bolts and maybe hinging or using prongs on the front and dzus fasteners on the back? Anyone know where 3/16 or smaller dzus fasteners, preferably D-ring type, could be found?

I'm also kicking around ideas for mounting that tow release. I don't want to relive the screw plate and weaken it, so I suppose I could add some spacer blocks to the forward part of the rear box beam. I should figure it out before I sheet the rear of the center section.

JeffinTD

Here you go.




I haven't decided on the bomb bays yet. I guess I will jump off of that bridge when I get to building the fuse. I am curious about RC skydivers, though.

Anyway, won't be any building for a bit. I've got a class to go to tomorrow and work after that.

malitape

My Feedback: (213)

PM sent

pete

Bax

My Feedback: (11)

Here you go! Makes nice, square holes! (heh, heh)

http://www.northerntool.com/shop/too...2050_200312050



However, I think he meant holes that were absolutely perpendicular to the surface (square to the surface).

malitape

My Feedback: (213)

Jeff, what do you think about these statements?
"There is a huge diffrence in the quality of the two; BTE is far above AMR. Both in design and material.
I have built kits from both and I will not build an AMR kit again. " "What was wrong with the AMR kit?
The wood is not as good, laser cut against machined. Designs are flawed in some areas that have
lead to the loss of the aircraft. They are unwilling to admit errors and issues. Other than that AMR is fine."
I copied these statements from another tele thread.

pete

JeffinTD

I haven't built am AMR kit, so I pretty much know what you probably found by googling around.

Regarding the PM about the weights, I'm not sure what they weigh and they tend to vary. They are wheel weights that have been melted down and had the steel skimmed off the top, fluxed off some other impurities, and poured into an iron muffin pan. I only have these because I cast bullets for handloading, and back in the day you could walk into a service station with $10 and cart off a few 5 gallon buckets of used weights. I've used sockets or whatever for weight before, and some folks like to use lead shot sewn into a bag (or old pant leg). Laminating stuff like that there is really no way to clamp things, and other times when gluing something up you may need something to keep one edge of the assembly from pulling up from the work surface.

How many clamps you might need I suppose depends on the type of construction and the size of the plane.

It is gonna be a while before I get any time to work on this. Still mulling over how to mount the tow release, possibly using plexiglass for the center section hatch, and how to construct flaps.

I'll have to hand cut one aft rib, and modify the others. I'm not sure what angle to make the bevel at the front, either.

Can anyone give me a good idea of how much deflection the flaps should be capable of?

soarrich

My Feedback: (98)

From 1* to 45* you get more lift, after 45* you just increase drag. If you hinge the flap on the bottom it will be effectively larger than if you hinge it on the top.

JeffinTD

Thanks very much. That would be the way to do it.

malitape

My Feedback: (213)

Jeff, when you get to install the flaps, pls take a couple of pics. I need to know how to do that.

"If you hinge the flap on the bottom it will be effectively larger than if you hinge it on the top"

pete

JeffinTD

Well, here's a couple pics of the center section with sheeting on the bottom of the front and rear, on the front, and stock added to the front corners, and the ply for hold down of the hatch. Once the glue dries, it will be time to block sand the top and sheet the top of the forward and aft parts, and make a hatch.

I may seal a garbage bag in the front part, since sooner or later...

I think I've abandoned making a clear skylight hatch (can always make one of each), but I think I will use latches on the rear instead of the 4 nylon screws to retain the hatch.





Flap wise, let me post up what I was contemplating, if anyone has any tips.

Here are the three types of ribs in the wing design.



The upper ones (W1) are for the inboard end and first bay, which get sheeted. The forward part of the rib is in two pieces as the plywood tongue that attaches to the center section passes through. It also has the shoulders for the main spar deeper, as spacers get added from the inboard edge of the wing to the first of the second type of rib, both on top and below the ply tongue.

The second set of ribs down are for the area outboard of the sheeted 1st bay to the inboard edge of the aileron.

The third set of ribs is for the section of wing that has aileron.

The only difference between the forward part of those two rib types is the length of the tab at the aft end. On the part without ailerons, the tab runs half way through between the aft spars, with the tab on the rear part of the rib meeting it in the middle. 1/8 spar webbing is called for on both sides.

On the rib for the aileron bay, the tab extends the width of the spars, to tie in to the sheeting at the aft end of the wing that forms the aileron bay.

So, what I'm thinking...

On the area to have flaps, I can just glue a short piece of the appropriate stock behind each rib, between the aft spars, so they tie into the sheeting at the aft of the wing. Then web the front of the spar as usual.

Rib wise, I can cut them 1/4" shorter than where the shoulder is, to account for 1/8" sheeting at the rear of the wing, and at the front of the flap. Then I was thinking of using 1/4" triangle stock at the forward top of the flap (to support the 1/8 sheeting so it doesn't get pulled in when shrinking covering) and at the bottom forward corner of the flap (to hinge to, and add rigidity).

I'm also thinking I'll add a notch on the forward part of the bottom of the flap, to accommodate a strip of 1/8 sheeting as is done on the ailerons.

It would look something like this sketch, except disregard the square (wouldn't fully support the hinge) and the notch for sheeting would extend farther back.




Am I on the right track? Suggestions?

JeffinTD

Well, here is the center section sheeted, with the hatch built with a lip to catch what was intended to be the screw plate on the front, and spring hatch latches on the back to catch that screw plate. I also added some thin bass wood with the grain running front to back to make it a bit more ridged.





I won't glue the catches in until after it is covered. I didn't really want a knob sticking out of the wing but it won't stick up very high.





With the center section complete, it gets pinned in place over the root of the wing on the plan, propped up off the table on the far side 1/4". This is supposed to give 2 degree dihedral, and it measures right at 92 on the nose.



Since the disk sander worked well for splice joints, I set the deck to that angle via the gauge (the indicator on the deck is way off), and squared a board to the disk on the other axis for a fence (the channel for the miter is also way off).



Worked good, and got a perfect fit.

The plans call for trimming the bottom spars at the outboard edge of the last rib, and the upper spars cut at 45 degrees to support the sheeting at the wing tip. I went ahead and cut the lower spars at 45 degrees to add support to the sheeting. Takes a bit of to get the length perfect with angle cuts on both ends.

Then the bottom of the main spar gets pinned in place, and a rib is used to accurately pin down the mid and trailing edge spars.



Now the fun part, I finally get to glue in ribs. I thought I had made way too many of the aluminum angles but it turned out I had just the right number.





The old back gets a bit tired leaning over that wide wing to get good glue penetration, so I'm letting it cure.

Next up will be adding the sheeting to the bottom of the 1st bay, which fits between the first of the non-sheeted ribs and the center section. Then a spacer gets glued on the spar (cut at 2 degrees inboard).

From there the ply tongues get fitted in the center section, and against the first of the W2 ribs, the location of the holes get marked and drilled...

JeffinTD

So, here is the bottom of the first bay, sheeted, and a piece of spacer setting up on top of the main spar. The spacer also gets the 2 degree cut on the end where it meets the center box.



The plywood tongues then get fitted in the box beams and slid against the first type 2 rib, holes get marked through the box beam and drilled, and they get epoxied to the forward and aft spars. Screws go in while the glue sets. Though there is a long area of contact, they are still getting glued to balsa, so I went ahead and perforated that area of the spar and epoxified the full width. With the wing loading on this thing I figured it best to err on the side of more glue, IE I don't think I'd ever notice an extra ounce or two of extra weight from a bit of extra extra glue, but a person might notice (in a bad way) if it were built a bit stingy on glue.



Once that sets up, the type 1 ribs go in for the first bay that gets sheeted. I also put the trailing edge down for that bay, and made balsa spacers for the ends of the type 2 ribs that will connect them to the sheeting that will be the face of the flap bay.



Once that gets set up, another spacer gets cut to fit above the tongue of the main spar, 2 degrees again, and it is supported by the type 1 ribs while epoxy sets.



The front strip of sheeting that also forms part of the leading edge then gets notched to remove the part outboard and behind the front of the last rib, and the wingtip bottom gets beveled at 45 degrees and propped in place. Because I cut the ends of the bottom spar at 45 degrees, I was able to just glue it down...



I was pretty happy with the fit.

Then the leading edge laminate, the laminated top spar, the top of the aft spar, and the turbulator spar get the 2 degree cut on one end, and get cut at 45 degrees at the other. The turbulator spar isn't flat to the bottom of the wing, so it is a compound miter on one end and a 2 degree miter on the other.



I think I got a pretty good fit.

If anyone needs to know how to do those without running back and forth from the saw to the table, just ask... someone else. I made several cuts on the end of the turbulator to get the angle right before attempting to cut it to length.

I figure it is better to measure and make a bunch of test-fit/cut-a-little-more cycles than it is to have to try to "un-cut" something.

Leading edge is now setting up to the front of the ribs and the bottom sheeting. It looks like I'm smashing the heck out of the wing, but the clamps have very light pressure. Just enough to keep the leading edge snug to the ribs for a tight strong glue joint...



The next time I'm by Harbor Freight, I think I'll snag about half a dozen more of those blue clamps. They are light weight, and the squared off jaws make it easy to set them up so the weight of the clamps is on the table and they are stable.

Once these set up, the three spars get glued in, spar webbing goes on, mounts for aileron and flap servos need to be built and installed, along with the hard point for the strut. Once that has cured, I should be good to take the wing off the center section and off the table. I think I may want to block sand the back edge of the rear spars just a bit before adding the sheeting to the aileron/flap bay. The top of the first bay will also need to be sheeted.

JeffinTD

BTW, I'd still like to hear from an expert on the thoughts I posted on how to build the flaps....

LargeScale88

Wow the wing is turning out great. I had so much fun building my senior telemaster. Its so easy have a flat bottom wing, you can just throw the ribs and some glue down flat and your good to go.

May I ask, where did you purchase the Squares that you are using to keep the ribs 90 degrees?? I WANT SOME!!

Thanks
Jason

JeffinTD

Those little aluminum squares clamped to the ribs? They are just 1.5" extruded angle stock cut to 2" lengths with a metal cutting blade in my miter saw.

You can get a chunk of that stuff at any decent hardware store, just check them for square and tweak as necessary. Seems China has a hard time making an accurate right angle....

JeffinTD

Let's see, where did I leave off...

Top of the spars get glued on, a piece of triangle stock that makes up part of the leading edge gets glued on to the top of the laminated leading edge part I just glued on, and a 1" wide piece of 1/8 balsa (spliced previously to 6) gets glued on behind the triangle stock. More compound miter pieces to fit.



Spar webbing is continuous across the first bay. Two 3" wide pieces are used everywhere else, leaving a gap in the middle. The instructions note the ply tongues rely on the integrity of the glue joints here, so I fitted and clamped them carefully. They are 1/8 short of the top of the spar, to accommodate sheeting of the first bay.



A lot of spar webs to cut and glue in... In retrospect, I should not have let little glue gussets dry between the ribs and spar, as I had to trim that out to get a good fit on the webbing. Usually I would leave that deliberately, but I wasn't thinking of webbing going on there.



I wasn't thinking either when I put little extensions behind the ribs in the aft spars, where the flaps would go. No biggie, but I had to cut a bit of one out to accommodate the strut mount plate, which spans across the top of the main, mid, and aft spar and secured with epoxy. I actually ended up removing the part of the spacer outboard of the edge of the rib, to more easily fit negative load braces.



Here's another piece of 1/8 sheeting getting installed ahead of the aft spar. You can also see the negative load brace between the top of the strut plate and the bottom of the main spar (ahead of where the C-clamp is). Aft spar is similar.



Another shot of that strip, and the compound miter to meet the wing tip.



Spar web gluing slogging along, due to not having enough big clamps, I decided to remove the center section and sheet the top of the 1st bay. Tugged on the center section, and it wouldn't move. I reached in with a knife blade, fearing that epoxy had wicked into the box beam. Then it dawned on me, it might come off easier if I took the bolts off (dummy).



Finished up the spar webs, and sheeted the face of the aileron and flap bay. Sheeting mitered to fit the wing tip, and angle spliced to make the length.



Man, that thing is a lumber yard.



Main part of wing half is pretty much done. It seems to sit pretty perfectly flat and straight. Doing the leading edge is going to leave me knee deep in shavings and saw dust I'm sure. A hard wood spacer block needs to be added to the underside of the strut plate, and servo mounts need to be constructed. I'll block sand the aileron/flap bay a bit, and make a rib/spacer kind of thing for the inboard surface of the bay.

Then it is on to building the aileron and flap.

Here is how I am thinking of cutting the aft ribs to make flap ribs, drawn out on one of the ribs.



1/8 sheeting across the front, with triangle stock top and bottom, the top one getting beveled to match the airfoil.

I'd sure like some input on this plan before I cut those...

jbarnes

Jeff, I've built two of these over the years. Both were lost due to strut failure. As you can see during your wing construction that there is no support for the wing. Failure of the wing strut causes the wing to fold up immeadiatly. When building the wing put blind nut in the attachment point of the strut so you can have something strong to bolt that strut to. The strut material they give you will fail, just a matter of when. I'd replace the strut with a solid metal strut rather than the ply balsa combination they use. On the bottom of the fuse run a metal strap from one side of the fuse to the other so the struts are connected. Typically the strut will pull the side of the fuse out or will pull through the ply strut. If you can fix that strut issue to make it failsafe you may have a long term model on your hands.

Nice slow flying bird, I launched alot of sailplanes with mine.

jbarnes

Oh, forgot to mention. Flaps are useless on this bird. It flies so slow there is no need to waste your time trying to build flaps. Jerry.

JeffinTD

Thanks for the tips.

I was already planning on using blind nuts on both ends of the struts, and maybe a bit of ply to connect the strut plate directly to the top main stringers, and triangle stock. I like the idea of metal across the bottom. With 4 satellite receivers I plan to use, I don't think it would cause problems.

I was also thinking of fiberglass over the struts. A piece of metal strip down the center, along with the ply would be another thought.

I figured this thing would fly slow, but would probably also float forever in ground effect, so I was thinking flaps might help. Also I understand large flaps are helpful for float flying.

Anyway, I greatly appreciate the tips.

Please chime in again.

JeffinTD

PS. Very nice looking plane. What a shame to have lost it.

JeffinTD

Well, today I went out to shoot some landings. Another flier showed up, who also builds. I've seen a biplane of his that is just spectacular. Anyway, he was kind enough to let me pick his brain in regard to how I want to construct the flaps.

From our conversation I decided to ditch the triangle stock idea, and use square stock along the bottom, and strips of 1/8 sheeting between the ribs and against the sheeting of the front face. Kind of like rib stiffeners, but along the front. Mainly I was going to put stock across the front because I was concerned the covering would pull the forward sheeting in, and using stiffeners will strengthen the front sheeting on that axis in a lighter and simpler way.

It should be stronger where it needs strength, easier to build, and I also have the wood on hand to do it.



I went ahead and pulled the wing off the table, and did some rough block sanding, and inspected the glue joints. I have a piece or two of spar webbing along the bottom I will need to touch up. Otherwise it looks pretty good I think.





I went ahead and put a piece of sheet on the inboard side of the flap bay. Since the rib that would have doubled there will get used in the flap, this spaces the bay out to even with the doubled rib ahead of it.



Setting up to build aileron...



Leading edge gets pinned on to the trailing spar, using an aileron rib to get the height right. Then a rib is used to pin down the sheeting under the trailing edge in the correct location, a ply support plate for the control horn gets glued on, and forward bottom sheet gets pinned in place and glued to the ply piece.



In go the ribs. I cut the bottom pieces at 45 degrees again, to make the tip match how I changed the tip on the main part of the wing. I messed up with the trailing edge sheeting. The tip piece ends at the trailing edge, so I spliced sheeting the width of the trailing edge back on. Actually that is probably the easier way to make the part forward of where the trailing edge will go 45 degrees.



Wing tip bottom gets beveled, and glued to the beveled bottom pieces. Trailing edge has also been installed.



A piece of hard wood then goes on the ply plate, overlapping where the ply meets the balsa sheet stock. Another piece of balsa sheeting goes on top of the ply rearward to the trailing edge, overlapping where the ply is glued to the trailing edge sheeting.

While that is setting up, I went to modify the rear ribs for flaps. A little hesitant about this, but here goes...



Then I cut out the other pieces of the rib. Here are the components for the flaps. Sheeting to form the front, sheeting for the bottom front, square stock that will go in the bottom front (and support hinges), trailing edge bottom sheet, and trailing edge stock.



Mocked up flap rib to check my work before cutting the rest of the ribs.



Shamelessly plagiarized the aileron for flap construction... Pinned front sheeting against aft spar, used rib to locate trailing edge bottom sheeting, and cut a scrap of 1/8 ply to glue between for control horn support. Then cut the sheeting for the front bottom and glued to the ply and front sheeting.



In goes the square stock, which will overlap the plywood and bottom leading balsa sheeting.



In go the ribs...



Trailing edge goes on, and a block of hardwood for the control horn goes on the ply. I then also put on a strip of 1/8 balsa between that block and the trailing edge, as done on the aileron.



Done for the day. To finish the flap and aileron, the aileron gets sanded a bit and sheeting goes on the front, along with rib stiffener on the inboard rib. Flap will get rib stiffner on both ends, and similar strips of balsa between the ribs across the front.

soarrich

My Feedback: (98)

As a scratch-builder I was wondering what thickness of wood do they use for the ribs, and what's the rib spacing?

JeffinTD

Can you give me a suggestion or a link for metal wing strut tubing of appropriate size?