A Ringmaster Bi-Plane
 

I ordered 2 sets of Ringmaster Jr ribs from Brodak late last week. They arrived today.


I also bought some sheet balsa for a built up fuse and some hollow carbon fibre rods that will accept 4/40 bolts, at the LHS today. Alas they still do not have any Lite Ply. I desperately need some 1/8 Lite Ply. I may have to work up an order next payday and order some wood online.


Now I will describe what I am building. A Bi-Plane Ringmaster based on the Ringmaster Jr.


Power is to be Super Tiger .34.


I am going to stretch the wings to 36" from the original 30". I am adding a 4" center section to the wings. With 1" hollowed out balsa wing tips the wings will be 36". I was originally just going to add a 4" straight section (lazy and easy), but I will make them same taper as the rest of the wing to keep the same look and planform. The center sections will add 61 square inches total bringing the total wing area to 470 square inches.


The fuse will be stretched to move the empennage back. I will use the proportions of Pat Johnston Ringmaster Bibe 1099.


At this time I am planning on some short center section flaps May be 1/3 to 1/2 span, both top and bottom wings.


The Carbon Fibre rods are to make up some N struts. both interplane and cabane struts. I needed them hollow to accept 4/40 threaded rod. This is going to be a take apart, well just the wings. I do have transport (PT Cruiser) and storage issues.


The last time I built a bi-plane I was in my junior or sophomore year in high school, scratch built from my own plans. I have had a couple of bibes since (RC) but the were second hand buys.

I punched out 1 panel of ribs to see how much wider the root chord is going to be and my extension adds 5/8" to the root chord, so the root will be 8 1/4". the tip will remain 6".


I still have to buy spar, LE and TE stock.


This will be my first Ringmaster of any kind.





So this is going to be a challenge and fun. :cool:


Ken http://www.rcuniverse.com/forum/atta...mentid=1913704

It wouldn't be the first one. Check out these on Brotherhood of the Ring:

http://www.brotherhoodofthering.info...osts=9&start=1

http://www.brotherhoodofthering.info...osts=1&start=1

I just now noticed that I ended up with a smiley in the thread title. Did not intend to do that and now I can't figure out how to remove it.

Ken

I have been try to get some 1/8" lite at the LHS for over a month now. Well I was near another hobby shop on business Wednesday so I paid them a visit and scored 2 sheets of 12" x 24", so that will not be a show stopper.

Stopped by a fellow The Brotherhood of the Ring this afternoon that live about 3 miles from me, for a first time meet. Then afterwards I went to the LHS and bought T.E. and L.E. stock. I will need to carve and and sand the L.E. stock to shape. They did not have any 1/2 L.E. stock so I got some square stock. Just mare work is all, and that is OK.

I also bought some aluminum shafts that match the round holes in the ribs. I will build with all the ribs mounted on them above my magnetic building board. I cut into 6" lengths a wood yard stick. Next I need to mount a magnet to each section. My magnetic board will set on top of a balsa laminate building board. It is pretty close to dead on, but at one end their is a very slight bow, about 3 or 4 paper thicknesses as check using my good aluminum 4' level. I left it on the card table to long. it was more but I leaned it against the wall at a pretty good angle and it almost fully straightened out. Now I have it hanging vertical and will recheck it in 2 days.

I have to make 3 center ribs. I will make 4, just easier. I will bolt 1 wing panel of ribs together with to blanks on the end, and the shape the 2 extra ribs. I will just have to real careful not alter the original ribs.

The other thing is original ribs w1 and w2 are 1/16" undersize for the center sheeting of the inner 4 rib bays. Well my center sheeting is going to move inboard and I am only going to sheet the 4 inner rib bays. So I will just cap strip w1 and w2.

I also picked up a 6 ounce round clunk tank. Seems like a lot of fuel for this thing, maybe a 4 ounce would be better? I do know that little ST .34 is a lot thirstier than my OS .25s, a lot more. It is a direct bolt in and weight match fo them, and several times I swapped in it for a more giddy up go. It has it too.

Kenhttp://www.rcuniverse.com/forum/atta...mentid=1914642

I have managed to cut two new inner ribs. It was not the cutting that was slow or difficult, but rather generating the pattern for them.

We recently had to replace our old printer. We were pretty sick of the cheap thing. I could not alter print size for one thing. Now I can in 1% increments.

I had calculated that the new inner most rib should be 1.04% bigger. So I scanned in the original W1 and W2 and printed to those sizes. It was actually more work and trial and error than I have described, but basically it worked. Then I just had to cut them out.

Now to make another of both.

I have started on my rod holders. The magnets are glued on. I need to add a front stop and clamp bars. Then I can start building wings. The wing jig I am making will also work for other wings. Made no sense to make a one use jig. I may use bigger rods for bigger wings. These are a little flimsy but were a perfect fit for the existing holes. I may look at fitting something inside the rods I have now to stiffen them.

I can't figure out how to include the pdf of the new ribs.


http://www.rcuniverse.com/forum/atta...mentid=1915337


Ken

I did not get as far this weekend as I thought I would. I had expected to accomplish the basic framming of the wings. Or things to do and I had more prep work to do than I originally thought.


I am going to use a more normal spar system, top and bottom spars on each wing. Those had to be cut. I had place my balsa laminate build board under the magnetic on, started positioning ribs and went oh crap. I ain't ready Where are my spar slots. And hey I can't count, I am short 2 ribs, and I thought I was making 1 extra for a possible RC version down the road. So make 1 more W1a and W2a and use the 2 supposedly spares.


Then it was time to cut spar slots. Well slow down Sherlock, you still ain't firing on all cylinders obviously. I had become pretty heat stressed when I went out this morning to fly my little OS .10 trainer. Ended up on the ground at the end of the 1rst flight.


So I made the needed extra ribs and put them all the rods in the correct order but doubled up. Top and bottom wing ribs slotted at the same time W8,W8 W7, W7 all the way to the middle were it was W2a, W2a, then W4a, W4a, W4a, W4a, and the back to W2a, and continuing the pattern to the last rib on the opposite wing panel. .
http://www.rcuniverse.com/forum/atta...mentid=1916126
I removed the balsa building board from under the magnetic board to avoid it taking a set. I am building on top of a card table with a 2" sheet of insulation foam on top of it. So there are some issues with trueness.


Maybe later this week I can start framing the two wings.


Need to get 4 balsa 1/4" square spar pieces. Also some 1/16" balsa sheet.


I am thinking of building the stab and elevator a bit different than the standard sheet tail. I am strongly considering laminating 1/16 sheet balsa to a core of $tree foam board paper off. Stick L.E. and T.E.s. It should be only slightly heavier than a simple sheet tail, but a bunch stiffer. The stab/elevator will have an area of around 103 square inches. That is not real big but might possibly be pushing 1/8" sheet. I am very open to input about this.
http://www.rcuniverse.com/forum/atta...mentid=1916127http://www.rcuniverse.com/forum/atta...mentid=1916128http://www.rcuniverse.com/forum/atta...mentid=1916129
Ken

Ken, i made this setup this weekend to build a wing for my Brodak Shoestring. I made a tool to cut the holes in the ribs with a piece of 3/8" od copper tubeing with a 5/16" drill bit inside of it for a guide. I filed teeth onto the tubeing then inserted the drill bit into the existing 5/16" holes that were allready in the ribs. I inserted the drill bit end into the holes in the ribs and turned the tubeing by hand & it expanded the holes perfectly to 3/8" dia for me. I expanded the holes because i like you wanted the guide rods to be stiffer and not sag. I had 3/8" solid rod easily available to me and used angle iron on the ends to support the rods. I held the rods from moveing with end blocks i drilled & tapped & used 1/4-20 bolts to hold the rods. A C clamp on one end kept everything from moveing....Gene

Now that is one great ideal Gene. I love it. I also notice what I assume to be an alignment tool gauge in the second pic I will borrow that also.

I made a clamp bar (just some scrap 1/4 sqr bass) to hold the rods to the support stands. Does the trick very well.

Ken

Flyingagain, the tool is to space the ribs equally and keep them 90degrees to each other. It helps to keep the build moveing along faster. I hope you keep posting pics of your build as you proceed....Gene

That is just what I thought it was for. I had been trying to come of with something. I will just borrow your ideal.
I will keep posting. thru the maiden flight. This build will take a bit as I mostly just work on builds on the weekend. Just to wore out after work.

Ken

Ken, you sound just like me! I only work on my stuff on weekends or holidays for the same reason. It will take me a month or so to complete my Shoestring, and thats if i dont get interrupted with honey dos........Gene

I had a Dr app this morning. That took a while. And then some honey does,ect.

But then I got some work time in on this bird. I got one spar tacked in, and all the ribs spaced out I borrowed you ideal there Gene. It worked like a charm. Made a small change though. A horizontal piece to align the ribs at 90 degrees to the spar at the same time they are being space apart 2", aligned vertically.



And now I have ran into an issue. My T.E. stock has a serious crown in it. It is 1" x 1/4" stock. To a lesser extent the L.E. stock is also crowned.

My inclination is to do a rather extend soak in water and then clamp it straight and allow it to dry for 12-24 hours. Not sure they won't twist as soon as I unclamp them though. But I guess I have nothing to lose.

Kenhttp://www.rcuniverse.com/forum/atta...mentid=1916727http://www.rcuniverse.com/forum/atta...mentid=1916728http://www.rcuniverse.com/forum/atta...mentid=1916729

Rub a dub dub. 4 sticks in a tub (bath tub that is).

I soaked the L.E and T.E pieces in the bathtub. I had to stop when the wife decided she wanted a bath. They were very limber. So now they are clamped down on my building board butted up against my 4' level.

We will see how that works.

Ken

After I removed the four pieces, they sprung back.
So one more try. This time I soaked them for over 12 hours. Then I did something different when clamping them back down. I used some scrap 1/8" spruce sticks and broke it into a bunch of short pieces. I have those under the wood and behind the wood against the level. This makes an air space all around the wood I am trying to straighten. Maybe even drying will help. I will check on them in about 24 hours.

Going to go to the LHS and see if I can find some straight pieces also.

At this point; work stoppage.

A question to anyone. In this kind of situation do you try to straighten the wood like I am doing or should I being glueing it on the the ribs as is why wet and flexible? Seems like if I did the later it might turn the wing into a pretzel when it dried.

Ken

I went to the LHS to day and sorted thru every piece of the correct size they had. I think I got lucky. I found (2) 1/2"square pieces and (2) 1/4 x 1" T.E pieces that are very close to true <1/16" of crown and real light weight no visible grain stock. I sat on the floor and dug thru their stock.


I have the new stock lightly rubber banded together hanging from a hook straight up and down. Don't wan't introduce any issues now.


The original pieces are still drying taking up my board. I will wait more before I pull them. They may rescue and they may not. But now they are not going to hold me up.


Got a church event tonight. so all will wait till after.


Ken

A Rinfmaster Bi-Plane
 

Welcome back, and Interesting!

You could try lashing the soaked 1/2 squares wedged apart the amount they are out of true when dry, and letting them dry.

Another odd thing I came across not too long ago; The cheapest white vinegar makes balsa VERY limp. I was able to wrap straight grain 1/32 around an X-Acto #1 handle without splitting. When dry, it held shape.

Two considerations: I have no idea how this affects the strength of the wood afterward. And, thin sheet can be saturated thoroughly, but will 1/2 square soak that deep?

Besta luk!

Hi Lou. Nice of you to drop in.

I know ammonia works well, but could not use it in the apartment. I have to be real careful because I am an asthmatic.

Anyway I cheated and bought new wood. Sorted thru the bin and found some really good stock.

So I finally got one wing framed up. A ton of work left on it yet, but that is half the reason I scratch build.

Ken

Ken,
I tried to reply to the email relay of your post. Don't know if it got through...

I reminded that I was talking about white vinegar, not ammonia. Laundry ammonia makes me suffer, too. Vinegar has a sharp odor, but might not bother your asthma - at least not as much as laundry ammonia.

It also seems to work quicker, and penetrate more deeply than ammonia. ...In thinner sheet balsa, anyway. No idea how well it will soak into thick section balsa, like 1/2" sq.

Ammonia also seems to stain balsa yellow. Haven't noticed that with "distilled white vinegar." Dried after "forming," vinegar-treated balsa seems as stiff and clear as before. Ultimate test will be how well it conforms to mild 3D forming. MIGHT just accomodate some crushing, instead of the bias-slitting needed for other 'treatments,' like the area around the final front section on full-fuselage models.

In any case, you've found the wood you need! I'll keep an eager eye on your progress!

Thanks for the info Lou. Nope never got a pm or email. This site has been even flakier than before the rebuild.

An answer for blasa sticks, L.E.s T.Es just might be a piece of plastic tubeing intended for plumbing. Cap an end, put your parts in, and fill with vinegar, in the vertical position. Let soak. Maybe lightly cap the open end for a real long soak. I might just might give the vinegar a try on the fuse (full built up). Fact is I am rather sure I will.

Always glad to learn a new thing.

I won't get much work done this weekend. Cleaning the room (it is a bedroom) up for a visit from my step son that we have not seen in about 5 years. Also going to replace the card table I have been working on with my computer desk. Will put a cover on it to protect it. Should make a heck of a lot better work table. It is an oak desk I designed and built myself about 30 years ago. Oh man is it ever solid. But once set back up I hope to make some good progress.

Ken

Cleaning out part of the room We found that the air conditioner was leaking condensation like crazy all over that part of the room and the hallway opposite it. So I got half the room emptied So maintenance can replace the damaged sheet rock and carpet. Both my wife and I are highly allergic to mold. Last time I was exposed I ended up in the hospital for a bit.


So I am still cleaning up the spare bedroom and vacuuming it. Can't move the desk yet.


So I hope to make progress next weekend on the bibe.


Ken

With much thanks to Dee (of The Brotherhood of The Ring) one of these will really spice up my bibe.


I have to get it framed up before the wife can color scheme it for me. She is the official airplane decorator. And really does very well at it.


Ken

I am building again. The second wing is on the board.


I got the desk moved in. Checked level on it. and the back end was dead on. The front was bowed about 3/32. It makes sense. The back is just a really big I beam, and the front is not. So after about 30 years with computers sitting on and full drawers it settled. So I put a sheet of 3/4" MDF on top to protect the desk and so I could shim it to true. One spot is off by the thickness of two sheets of paper. That is pretty darn close. Then on top of that sits my balsa building board and on top of that my steel magnetic building board. It is all pretty close. I will routinely check it. Well heck this darn apartment is constantly shifting. I have to add a 1/2" foam shim to the patio door again. It has shifted that much in less than a year.


I am going to put a shelf system in back of the desk to give me some storage room.


But for now it is building time.


Ken

I checked out HK's cote on line. Looks fine to me. I showed the wife the checkered cote and she said this RM Bibe is getting the blue and white checkered on the bottom of the wings.

http://www.hobbyking.com/hobbyking/s..._5mtr_404.html

Ken

Both wings are framed up.

That second wing framed up in just 1 evening. The first took 2 or 3 to get fully framed up.

Ken

Starting to lay out parts placement, so I can draw up my fuse. Just going to be a rough drawing.

I started by printing out the tail feathers. I have downloaded a PDF of a RM 19. it has 230 square" of wing. So I needed a little more than double the stab area. I had calculated that if I printed it out (the stab) at 1.45% I would end up with about 84 Square" or about 22% of wing area. So that is what I did and I actually ended up with 90 square" close enough. I will cut the tail feathers from 1/8" sheet balsa. So the stab is 6.25 wide at the root and 18.5" long. The vertical is printed to the same scale.

I naturally want this thing to balance with very little to no lead added. I will be able to shift the engine some while the fuse is still roughed in. I do not have enough parts finished to hang them and see where the cg ends up at and the shift. So going with my best guess and past experience. The cg could be off by this method. We will see.

The engine is a Super Tiger .34 rc @ 12.8 ounces with muffler. Same weight as a OS .35AX, 2 more than a .25. I will likely use a 11x5 prop.

So here is the placement measurements.
I am referencing everything from the back of the prop.

Prop to bottom wing L.E. =8.5"
Wing stagger will have the top wing L.E. 1.5" forward of the Bottom wing L.E.
Prop to Stab L.E. will be 25" and T.E. of bottom wing to stab is 8.5"
Prop to T.E. of elevator or fuse end is 31"

Ready to cut tail feathers now.

Ken