50% Christen Eagle - Page 2 - RC Groups
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Oct 03, 2012, 09:56 AM
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Speaking of trial and error, I just discovered an error on my part that will need addressing before further progress on the fuselage. Well, I'll take the heat on this but it really was a combo of kit instruction short commings and my subsequent decision. It has to do with the the fact that the fuselage notches were milled too small for the thicker supplied 6mm ply formers. Since none of them fit the 4.5 mm slots/notches I made the call to widen all in the aft direction, figuring the front of the former would not change. This did not become a problem until I noted that the aft most 6mm former, which forms the front of the cockpit area had to be pulled out of vertical to fully engage the pre-cut for length cabane mounts, running fore/aft. These seemed slightly too short to fully engage the notches in the last 6mm former. No big deal, as I beleived the canopy frame would cover. However. upon pulling out the carefully bubble wrapped canopy frame, for a test fit. I dicovered that the frame was not designed to cover but fit between the last 4.5 mm fram (now 6mm!) and the first former aft of cockpit. Strangely it needs about 1.5mm more room to fit properly and the cabane mounts are same distance short. Since the canopy frame has a substantial re-enforced fibreglas 90 deg.flange, I'm loath to simply shorten the canopy frame by sanding. I'm thinking it may be best to debond the the glue joint of the offending former and move it forward. Got the rest of the week to give it a think!

Also noted the canopy frame has a repair in the lower rear port side. This is a factory repair and looks to have been cracked when parted from the mold. Light relects differently on this section of the gloss coat, which is what caught my attention. Inside is an obvious patch showing thicker glass in this area and different color of the layup. Part is usable but it is one of those things FG parts guys frett over when sending something like this out. When I was making parts, this kind of thing came back from the customer about 50% of the time.
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Oct 08, 2012, 09:05 AM
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I had a free moment or two before the weekend and actually removed the offending former mentioned earlier. I initially brushed some water carefully on the glue joint and let it sit for ten minutes. Then scraped what i could out of the joint using the back side of an Exacto # 11 with a broken tip. I was also able to apply upward preasure from below, where the former's tangs extended thru the light ply carrier at the longerons. This got one end to come up just slightly. More water, more scraping, returning-repeating every ten miutes or so. In about an hour, it lifted out cleanly and virtually no damage. Only visible sign of trauma is water stain on the light ply carrier. This will show only when the canopy is removed, but looks like grain variation. I'm very pleased with the fix, thus far, and was glad it did not intrude on our wonderfull weekend.
Oct 10, 2012, 01:45 PM
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Spent yesterday repairing tools (table saw) and finalizing router table. This allowed me to experiment and then shape fin and rudder oulines. Also made a shaped sanding block radius to close approx of 11.5 R. I found a 7/8" diam broom handle, as a form. Needed to subract about 1mm from 1/2D of that handle to get very close to 11.5R. So I measured various thicknesses of sand paper and found an 80 grit garnet that was close to 1mm. I made a simple L by nailing a 3/4" sq stick to a 4"x 8"x 1/2" piece of ply. I used auto body "bondo" to form the radiused portion of the block (inside corner of L) and to stick the sand paper to the block at the same time. With paper stiking out both sides, the handle was clamped into the corner formed by the 3/4sq. and the ply. The sandpaper surface actually came out the same as the handle (DUH!) so will have to add another layer to get it just right. however I have used to rough out the initial shape of the LE/TE's and will shape. the router while good for getting things close does not allow the the bearing to ride the same for both sides. while the first pass is quite good, the second pass cuts too deep. Point of bearing contact changes with first pass). As a consequence the second pass required the router tool to be lowered so that the bearing contsacts the center line .So one is close, the other is not so close, but a couple of passes with the shaped sanding block trues and equalizes. Final shaping with second layer will come when all tail and wing tip outlines are rough cut. Today I'm hoping to jig up and cut the hinge slots for fin and rudder. All of this tooling will be used , as I said on other outlines and hinges.

Discovered that some of the kit provided pine was less than desirable (used the better stuff with matched grain and lighter weight on the stab and elevators). There was considerable tear out because of the wonky grain, when I attempted to rout the fin TE. It is still usable but it will require considerable spot filling, prior to final sanding. I will use epoxy and micro spheres on the worst and largest gap, for all other little sanding mishaps, I think lite wt. spackle will be fine.

I've decided that the covering material will be light weight Dacron, applied/filled with nitrate dope. Final finish will either be enamel or butyrate dope.
Oct 21, 2012, 11:49 PM
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Well, I got the fuselage turtle deck sheeted. It's 3 mm (1/8") thk balsa sheet. A very pleasing excersise. Several little things went wrong, but overall am pleased with the result. Stab mount tubes were finalized before the sheeting. Today I got the cowl fittings installed on the firewall and got the cowl drilled and test fit. All fittings and bolts will be removed and kept for re-installation after everything gets epoxy coat and or spar varnished in the interior.

Plan to start interior epoxy and FG tape of the major ply joints tommorow. This will mark end of progress on the fuslage for now. Need the lower wings to set the fillet pieces. So I guess I can finally start the wings.

Have noticed thay the plan shows tail brtace rigging attach at the aft edge of the fin is indicated higher than the front fin brace. In looking at You tube vids of same aircraft a couple of fellows have put the aft attach point at the very top of the fin. Photos of real aircraft, show the aft rigging point at same hty as front. I'm making this one more scale.

I have dry fit the central wing strut assembly (cabane ) but the intructions are very vague. The template is near useless and nothing fits well. . As the lower wing position is fixed in construction and the interplane struts come pre-assembled I'm going to wait until the upper wing is assembled. then will jig, rig, drill and bolt everything at once
Oct 23, 2012, 09:47 PM
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Started the lower left wing today. Got the beveled rails fitted in place and nailed down to the buildng board. These elevate and level the stucture off the board so that the full symetrical ribs can be added without rocking. As I cut the individual parts from the 3mm light ply carrier, I laid each one down on the plan. A full size drawing of every precut spar webbing piece is provided. However to my dismay EVERy WEB is too long,according to the parts drawings and rib layout. This could be shrinkage in the paper plan but I've noted some matching webs for corresponding bays wherefront spar and rear spar web pieces are not the same length. I've also noted that the CNC routing is of generally poorer fit in tabs and slots than those exhibited while assembling the fuselage. This is a high dollar kit. I t should be better engineered, or at least corrected so there are less fit problems at every turn!

So ,now do I build to the plan(a Lot of sanding!) or do I go with the precut assembly? I think I''ll go with the computer cut fit, as much as I can. I'm guessing this will accumlulatvely increase the total span by approx 1/4"-3/* (6-9mm) over the panel depicted on the plan. I figure if I keep everything parallel to rib layout shown, it won't be a problem. There is plenty of spar length in provided materials. Another concern is the correct dihedral fxed by spacing of the first three ribs. But maybe no big deal? I'm operating under the assumption that the CAD drawings were correct when originally rendered but that the CNC cut parts are "more" correct now.
Last edited by packardpursuit; Oct 23, 2012 at 09:53 PM.
Oct 25, 2012, 12:50 AM
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Got lwer left panel framed today. It came out 6 mm longer than the wing shown on the plan. The aileron bay spar, pre slotted for7 ribs, and was 3 mm longer than the bay indicated on the plan. I started at the tip. and worked inboard. Only one web had to be shortened.to keep every thing square to the plan. Will have to shoot for same overall when I build the right panel! Just finished cutting out all the parts for that one this evening. Parts from the thicker carriers need to sawn free. However the bulk of the parts(all kinds) are 2.5 and 3mm and easily removed by cutting thru the attach sems with a utility knife.

I will look into the possiblity of replacing kit cap strips (2.5x12mm) with narrower 4x6mm. IIRC, the rib caps at full size are 12mm wide!
Oct 29, 2012, 09:33 PM
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Got some goodnews/badnews today. Good news is that the servos fuel tank etc are on the way. Bdnews is that owner has doubled number of aileron servos and added two (three total) for rudder. I suppose that's for redundancy and oomph.

I've about had enough of the "intructions". It would be laughable if it weren't so sad. The CNC routing is a bad joke too. Not that its a bad thing(I guess it's better than having to cut everything from scratch), but there are so many simple things that should have been EASILY corrected that weren't.

Right now I'm wrestling witht the interplane strut mounts. Plans call out for 1/2 round molding of Pine, glued vertically to back side of front spar and front side of rear spar. A bolt passes vertically thru the end grain of these pieces securing the I struts. The kit supplies maple 1/2 round, but these still have to hold on to the face lamination of soft 3mm poplar ply. Again, no mention of the change in the instructions or why the change was made. Did pine blocks fail??

I don't know what the term in German is for this kind of stuff, but in Spanish I believe it's called "Merd de la Torro".
Oct 31, 2012, 05:22 PM
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I feel a bit better today. Have been in touch with customer's rep and parts are coming. Got the second lower wing panel nearly framed and it came out exactly the same length as the other. I was worried.The only thing that makes sense to me is that the plan shrank after printing. Appears to be about 5mm longer than the plan ,again. At least it's consistent.

I've leaned a thing or two. Go with your gut feeling! Everything that has gone wrong has come from my faulty interpretation of the "translated" instructions and/or "where did my modeling skills go!"

I finally found similar Eagle build over on Flying Giants. What he says about this kit I agree 90%!! That 10 percent is held in reserve for the fact that he likes the kit (I will be incorporating some of his mods, BTW!). I'm leaning toward not liking it at all and reminds me daily me as to why I haven't built a kit in years.
Last one was back in '82. I really like designing my own.
Nov 01, 2012, 11:00 PM
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On the First lower (left )wing panel, the tip laminations were wrapped about the ply carrier piece. Whole affair sort of "in the air" secured with nails driven vertically to hold the oozing balsa. This introduces a very messy affair right on ones work surface/plan. Also its rather hard to keep each strip centered. There had to be a better way.

I took the right tip carrier and traced it onto a piece of 3/4 ply, which I cut out and sanded to the inside of the line (made it disappear). When satsfied I had a good smooth representation of the tip circle, I covered it with a piece of plastic packaging tape. A form with a no stick surface. then glued each strip (4 total) in a neat stack around that and off the plan. when I romved it from its form it fit near perfectland no mess. I also discovered that by leaving the form long at both ends a single rubber band hooked on nails drivien in bothsides of the ply, it was easy to secure one end, then wrap the stack around to another pair of nails, where another rubber band held that end. Worked great!. and so much neater than nails driven into the worktop to hold the wet lams. Smooth semifinished tip bows not at all squirrely. it will also work for the upper wing tips.
Nov 05, 2012, 09:47 PM
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Went back to fuselage this afternoon, while glue is drying on a wing panel. Decided to tackled the lite ply side stringer problem. If ypu remember, I had trouble installing these. This mainly because they are inherenly weak. 2.5mm light ply simply does not make good stick stock! And these were/are still prone to easy breakage. Plus they are near impossible to keep straight. No doubt they wouldn't hold up to cover shrinkage.

I wondered if I might rip some hard 3/16 (5mm) square, then groove same to form a slotted cap strip I further wondered if they would hold the ply edge underneath straght? YES on both counts! Very pleased with this fix. Slot cut with table saw, about 1/16" deep and leaves about 1/32 to over lap each side of the stringer. I'll have to make a sanding tool to impart 1/2 round section to the larger stringers.

I have to wonder why the designer just didn't use balsa stringers in th e first place? He put them on the bottom of the fuselage! They are straight and haven't broken either of them, despite some unintentional rough handling. The ply side stringers snagged on EVERYTHING and the lovely snapping sounds cannot be good. Think I've solved the problem.I will be doing similar treament at rib caps, to straighten/STRENGTHEN wonkey ply ribs!.
Nov 09, 2012, 09:14 PM
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Well, got quite a bit done today. First off, I made a sanding block profiled to the Leading edges. Then i shaped the wings. Then I drilled installed the welded steel tube cabain struts,keeping an eye toward keeping everything true. After getting all the blind nuts in for that, I took them off and tackled the upper fuselage stringers. hardestbart was sanding the ply mount blades (ply members to which the cabane tresle bolts) flush with the formers. I knew this was going to be hard, so that why I cut the slope of decking (a bevel rip) back when i was dry fitting. Only had to take off 1/32" but that ply is hard to sand by hand! When those were done, I fit the wing tube into the fuselage and attempted to fit the lower wings. Couldn't get the tube to go int either wing!. spent an hour or so wet sanding the finish on the joiner tube ends till they went on. Don't look forward to pulling them off tommorrow, but will after fitting the wing saddle fillets. When that's done, the gear will be drilled axels fitted and tailwheel assembled. It should be sitting on its gear with all wheels/tires tommorrw evening... unless I go Steelhead fishing!
Nov 09, 2012, 09:16 PM
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Forgot to mention. I have been taking photos all along but alas, cannot seem to get them uploaded. However, I have a new plan that should see some images of the "pig" posted on-line by next week.
Nov 11, 2012, 12:01 AM
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Got the wing saddles installed, ready for final shaping, but it took near an hour just to work the wings loose! There has to be a better way , The mounting ube is getting harder to pull out of the wings rather than becoming easier. Yesturday I wet sanded the aluminum tube and it fit better Today it near took dynamite get the looser wing off??? I was verycarefull to wipe the tube down and let it dry before each test fit. The sleeve inside the wing is phenolic. We've had remarkablely cold weather this AM, with snow reported a few miles up the road. Could it be a temp thing?? Next I'll wet sand again and try Johnsons floor wax as a dry lube.

I did manage to get the gear mounted, axels and tires fitted.Tailwheel set in place, but couldn't locate my small Allen wrenches, so it will have to wait.

Thinking about radio and other internal installations (fuel and smoke tanks). Have to design rudder servo mount. Going with steerable tailwheel yoked to rudder, which is on a pull-pull system. Hoping oing to finalize the details on the two lowers tommorrow, sand and fill, etc. With final sanding they will be ready for cover
Nov 14, 2012, 11:31 PM
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With wing sadles shaped, I attempted to install the provided FG landing gear "hatch" from firewall to first bottom former. About 14"LOA. However, the part was too short! I added a 1/4" balsa doubler to the 1/4" ply former. trying to close the dist.ance. It now sort of fit, but was cut too crooked to allow any trimming at either front or back !! Now I appreciate why the few other on-line builds of this kit seem to use a home-made balsa hatch. I made one today. Next will start balsa infill from firewall to former just in front of cockpit. I suspect it's a good vibration dampening move. Kit provides flat FG panels to mimick the sheet aluminum panels of the prototypeEagle. Gluing these panels to the frame makes them structural Had I kown about the sheeting I would have adjusted the canopy cover ht to match the extra sheeting thickness, but since I followed the the instructions I'm now kinda committed so am compromizing with sheet infill (between formers and stringers on the sides only. All will be covered with the FG panels , with only the top of the fuselage and cocpit sides not having balsa substrate. Got to test fitting the FG panels and all is fine except for the top most, which goes between the cabane pylon struts. Yup, it too is too short! Misses the firewall or former in front to canopy frame by 1/4 inch, same as the bogus lower "hatch".

It's abundantly clear that this Eagle design is a cosmetic revamp of another aerobatic type aircraft from Modellbau and that the parts for the other kit have been provided as "common". Good idea, that is, if they indeed fit.
Nov 15, 2012, 12:06 AM
frequentflyer1's Avatar
Where are the pictures? A build thread without pictures? We want pictures.

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