propbuster

My Feedback: (1)

I appreciate you going to all the bother of actually putting all those pieces together yourself and keeping the tradition alive![8D]

grcourtney

My Feedback: (1)

mono the whole thing.

gary

Jeff Worsham

My Feedback: (28)

Here's my old XLT (pic from May '93) that was built by a friend. OS 61 RF. He stretched the fuse- 3" I think- just in front of the stab. Sure did pretty rolls! Was not such a benefit for loops and stall turns. Exhaust dumped out bottom of fuse through that tube, which was funny looking but quiet and clean. Just a little oil to wipe off the tail after flying. Fuse was glassed/painted, wing & stab monokoted. I've sold very few flyable airframes, this being one and always regretted it. Was great airplane for me and more than I needed for Novice and Sportsman.

klhoard

My Feedback: (10)

Between work and an ice storm, haven't made much progress. I did start framing up the fuse tonight. The slab of pink foam on the table is what I'm using the learn how to vacuum bag and try out different finishing techniques.

Stuart Chale

I built three back in teh 80's. The first toatally stock, pretty heavy. The next two working on weight savings lost about a pound on each one. No need for 3/32 wing sheeting. 1/16 is fine. Replace most or all of the balsa blocks with contest balsa. The balsa block for the front fop of the fuse was a brick painted to look like balsa on all of mine. Just don't drop it on your foot. I think my last one was about 8 1/2 or 8 3/4 pounds. I used an OPS Super 60 with spring air retracts on mine. (May have switched to mechanicals for the last one)

Good luck, a good flying airplane, although a bit large for the time.

Stuart C.

klhoard

My Feedback: (10)

Made good progress today. . . got both wings sheeted, retract holes cut, aileron holes cut. Trimmed the sheeting and sanded in the dihedral. After I got the dihedral sanded in, I went ahead and glued the wings together. We'll see if that was a wise move since I haven't added any of the leading, trailing or cap strips yet. . .

I also uploaded a copy of my spreadsheet showing weights of the various parts as I go along. Does anyone have weights for a 15cc Macs pipe, header, and 2.25" spinner?

grcourtney

My Feedback: (1)

What do you mean by sanding the dihedral in? Sanding the root to match up, as I remember it you build the wings upside down because the dihedral is cut into the bottom of the wing.

Gary

klhoard

My Feedback: (10)

According to the instructions the wings are both identical, so you elevate the tips until the top of the wing is straight and then sand the roots to match. . . I didn't check them with a micro-meter, but they appear to be so. . .
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Gary . . now you got me wondering because the instructions are photocopies of the original typewriter version, but the wings are manufactured by another company. I hope they kept everything faithful.
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doxilia

My Feedback: (3)

I think you guys are talking about the same thing. Different approaches to joining the panels.

I like your approach Keith as it assures you of identical incidences. That is, provided the cores are actually identical mirror images of each other, using the shucks is quite helpful.

Unfortunately, cores are rarely cut as mirror images and the core is not centered height wise in the block so you end up with an uneven height when you flip one of the panels in the shuck and join them at the root. In that case, Gary's method is preferable I think.

David.

klhoard

My Feedback: (10)

I did check the shucks and they were equal thickness, cores were cut by Wing Manufacturing, Inc. so I assume they were CNC cut and therefore identical.
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Sometimes it is better to be lucky than good!!

klhoard

My Feedback: (10)

Yesterday was "wing" day. . . . I've decided that I like joining the wing panels prior to adding the leading and trailing edges. I believe I can line up the cores more accurately by being able to see the skins than having the leading and trailing edges in the way and any inaccuracy that may have crept in when attaching those pieces. Doxilla brings up a good point, next time I'll measure the shucks as well. The only down side is that now you are having to handle an entire wing instead of wing halves. . . .
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The trailing edge on this kit is made up of two "standard size" pieces of balsa which must be custom shaped to match the wing. After thinking about how I was going to shape both of those pieces to fit the wing and also maintain accuracy, I caught sight of my hinge slotter. The hinges did an excellent job of both ensuring the ailerons were centered and held them in place while sanding. In the photos you will see that as usual, I took the long road and sanded between the several pieces of tape, then moved the tape to where I just sanded and repeated. Only at the end of the job did I figure out that I could have just taped the ends of the aileron and saved myself a bunch of hassle.
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The wingtips were made out of substantially different densities of wood. . . almost 20 grams difference in weight. If you've ever had a plane that would always roll off to one side when pulling up to a loop, this could be why. That small difference in weight is multiplied by the G-forces of your pull-up - a 20 gram difference on the bench is 80 gram difference in a 4-G pullup. And then you also multiply that by the moment arm of that weight difference all the way out on the wing tip. So. . . out comes the Dremel w/routing attachment. By routing different amounts of wood, I was able to match their weights within 2 grams.
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The fixed trailing edge was made of some pretty tough wood also. . . so I thought I may as well attempt to take off a finger tip while saving a couple grams. That's all I could get out of this operation and probably wouldn't do it again. .
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Well, at least now it's beginning to look like a wing. . .
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I've updated the weights to reflect the joined wing halves. . . still guestimating some of the engine components. . .

doxilia

My Feedback: (3)

Keith,

nice work.

Your keeping records of weights and offering it on the thread is a great idea and very useful to others who built the model - much appreciated.. Although I'll build an Escape one of these days which has different weights, this info will be a great guideline.

David.

glowplugboy

My Feedback: (17)

Outstanding thread, outstanding workmanship. I'm building a Great Escape and comparing notes. I wish I had the time to do it faster.....

klhoard

My Feedback: (10)

dox and glowplugboy,

Thanks for the kind words. . . I have found that forcing myself to keep a record of component weights really helps in making all of those little decisions along the way that add up to an overweight model. I've had many planes in the past that I didn't weigh until they were completely finished and then was shocked (Shocked!!!) at how much it weighed. Obviously, once the plane is finished it is almost a waste of time to weigh it since there is not much you can do to change the number. My last several airplanes were ARF's, so except for equipment selection I didn't have much control over weights of the individual pieces. However, on this plane I was able to knock 11 oz. off the finished weight before I even got my glue out by replacing the wing sheeting. When I ordered my vacuum bagging stuff, ACP offered 1/4" end grain balsa laminated with carbon fiber. Cutting out a new firewall from this stuff reduced the weight of this component over 50% - 40 grams to 18 grams. The same with replacing the heavy balsa bulkheads with honeycomb composite. The spreadsheet I'm keeping is updated with the current weight of everything, but I should have started a new column each time so I could see the weight reductions over time.

I have also found that the spreadsheet helps in future decisions on my "next plane". For instance, I used full-size servos on the ailerons, and digital mini's on the elevator. The digital mini's have more than enough grunt at 6V to run the ailerons so my next plane will use those on the wing, thus shaving off 30 grams, almost 1 oz. for no change in airplane performance. Also, while I used dual servos in the stabs to simplify the control linkages, I could easily have installed DEPS in the fuse and saved the weight (and $$$'s) of one mini servo - 26 grams (0.9 oz). While shaving 2 oz. off doesn't sound like much, if you do that 8 times your plane has now lost a pound. Like the politicians say - "A billion here, a billion there and pretty soon you're talking serious money!!"

glowplugboy

My Feedback: (17)

Yep, if you have the patience to do what you are doing, you can save alot of weight, especially on these Bridi designs. Built with the wood from the kit, the fuse could be used for batting practice. I have some half oz. carbon tissue I am considering laminating for the firewall as well. I will also be putting some of this tissue between the sheeting and the top of the wing where the landing gear mounts will be to firm up that area with minimum weight gain. As for the fuse sides on my Great Escape, the two 36" X 4" X 3/16" balsa sheets UNCUT weigh less than the kit supplied fuse sides. The trapezodial stock is mighty hard as well, but I don't care to try to duplicate it on my bandsaw.... I don't think mine would be accurate enough.

Weight savings like what you are talking about can make a huge difference on a hot summer day on verticals manuevers.

klhoard

My Feedback: (10)

The only part left to do on the wing was to shape the tips. I grabbed my 60 grit sanding bar and went to work on the top half of the right wing tip. It took about 15 minutes to get the shape correct and looking good - that was the easy part. The hard part is making the other 3 wingtip halves identical.
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I measured 7.5" up from the trailing edge and used my contour tool to copy the shape of the wingtip. I picked 7.5" because that is the highest contour on the wingtip and figured if I can get that right then I could fair the rest of the tip. On every new wintip I made a mark and began sanding perpendicular to the tip, slowly working my way until that one contour matched the tool. After that, it was easy to sand down the rest of the tip.

klhoard

My Feedback: (10)

The elevators were next. I used the same idea from the wing by installing the hinges then sanding the elevators to fit the stab. Then I drew parallel lines back from the hinge line on the elevators so I could sand in the bevel.

klhoard

My Feedback: (10)

Now that the wing and stabs are pretty much done, I started work on the fuselage. I began by drawing a centerline on my table and then taping down the fuse centered on this line. I need to nail down the fuse so I can get the firewall installed accurately, and I'll also put the stab in while I have the fuse secured, and maybe even the wing hold-downs.
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The protractor is another neat little tool I picked up at Home Depot right next to the contour copier thingy. The plans call for 2.5 degrees down thrust, and I want to add 2 degrees right thrust for myself. Having the fuse secured down to my building talble made it easy to confirm that the 2.5 degrees was already cut into the supplied fuselage sides. However, I need to measure the right thrust myself.
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I normally like to finish my building night on a job that requires epoxy or polyurethane glue so I can let it cure overnight and then continue the project in the morning. . . however, since it is now 1 a.m. and the fuse is secured upside down and it is critical that I get my upsies, downsies, rightsies, and lefties correct .. . . I'm going to finish job tomorrow morning after a couple cups of coffee. . .
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klhoard

My Feedback: (10)

Here are the before and after weights from the wingtip shaping. . .

NM2K

My Feedback: (14)

I'm with you, Gary. Life's too short to bother glassing and painting unless you really enjoy the process.


Ed Cregger

doxilia

My Feedback: (3)

Keith,

what's a good place to source this stuff?

David.

KLXMASTER14

Very nice work, Keith. You are moving along at a blistering pace. I like your method of shaping the tips using the contour tool. Did you say that you got that at Home Depot?

-Robert

klhoard

My Feedback: (10)

doxilla,

Here is the web site I ordered it from. I bought a .25" x 6" x 12" rectangle of the end-grain balsa, enough to do several firewalls. I don't think I could make it myself for $15.00 or do as nice a job as they do. I also got a square of the honeycomb laminate, perfect for servo trays and bulkheads. . . They also sell the vacuum bagging pieces.

http://www.acp-composites.com/home.php?cat=4707

KLX,

Yes, I got the countour tool and the protractor at Home Depot. They were hanging withing one arm's length of each other in the tool section. . .

doxilia

My Feedback: (3)

Oh yea. Gotta get me some of that stuff!

I just bid farewell to a 1/4" lite-ply FW. Heck, the 1/8" stuff sounds amazing too. I wonder if it is lighter (surely stiffer) than lite-ply. Must be but maybe a tad expensive to do a model entirely with composite formers.

Thanks Keith.

klhoard

My Feedback: (10)

I got up this morning, put the coffee on and went out to plan my building day. Looking at the firewall with a clear(er) head I realized I was test fitting the firewall not only upside down, but with left thrust. I'm really glad I listened to the little voice in my head that said - "C-I-L-L my Landlord" (wait, not THAT voice, the other voice) - "Keith. . . don't glue anything big after midnight . . "
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I started over by drawing a centerline on the firewall, then locating on the plans where the engine mount goes. The four holes on the firewall were located and drilled on the drill press. The original kit firewall was also drilled so I can attach a piece of PVCpipe and use it to handle the fuselage during painting. Since I didn't want the blind nuts to dig into the carbon sheeting, I made four plywood disks and glued them to the back of the firewall. Then I re-drilled the holes all the way thru the plywood disks and finished by opening up just the plywood holes for the blind nuts. I squeezed the blind nuts in pretty hard using my vice, and the end-grain balsa / carbon laminate didn't even come close to crushing - it is some pretty tough stuff!!
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After a quick test fit of the engine mount, I got out the glue and (hopefully correctly this time) installed the firewall. . .