FRED #528 construction log

Discussion in 'Member Project Logs' started by Abraham Leket, Sep 18, 2013.

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  1. Jul 19, 2014 #121

    Abraham Leket

    Abraham Leket

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    Root main spar: before wing root ribs- we have to construct the root main spar- it's lenght is a function of the cockpit width- I've constructed my cockpit to be 24" so my main root spar is 25.5".
    The main root spar -due to the cost of large width spruce (spar quality)- can be laminated from (2) 1" + (1) 3.25" + (1) 4" spruce.
    Those particular spruce width are well in stock and you dont have to wait 3 month for a fancy 7.25".
    Both spar sides are glued with 1/16" ply vertical web. Notice that I've marked the hollow
    areas in the spar-it might be usefull if the optional additional fuel tanks will be added in the root trailing edge area.
    P1010525.jpg
     
    Last edited: Jul 19, 2014
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  2. Jul 19, 2014 #122

    Abraham Leket

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    DRW 9- ROOT FITTINGS-front spar: it's a 20 pieces job constructed from 1/8" 4130 sheet and since we dont use CNC to shape and bore them-we construct a pair at a time-and match each and every pair in terms of holes alignment and shape. Once we accomplish this task-we tie each pair and its associated (if needed) sub-fitting and label them.
    In the picture-notice in top and bottom pairs-(2) port A1 fittings are tie to port A fitting pair -same is done with starboard A1 and starboard A . That way when every pair of fitting- when bolted to the front main root spar -its 1/4" holes will match.

    (4) B1 upper fittings (outer panel main spar) are not constructed at this point-they can wait for the wing outer panels construction stage.

    P1010524.jpg
     
    Last edited: Jul 19, 2014
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  3. Jul 26, 2014 #123

    Abraham Leket

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    DRW9- root main spar fittings installment: we make sure we got the right direction of the tapered end (in DRW9 its depicted upside down for some reason i.e- top fitting in the bottom drawing and lower fitting in the top drawing)- we use 1/4" construction bolts at this time- the right AN bolt shank size will be derived from the constrution bolt used area).
    The fittings protrude 1.5".
    BTW- the total weight of the root main spar with its fittings- a respectable 3.25Kg (7.15 Lb) :whistle:.
    P1010526.jpg
    P1010527.jpg
     
    Last edited: Jul 26, 2014
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  4. Jul 29, 2014 #124

    Abraham Leket

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    DRW9-Root Rear Spar is made out of selected high quality 1/2" spruce ("spar quality").
    Both ends are shaped (router is the best method) to fit the inner panel pivot 3/4" square steel cubic bar and its 3/8" pivot bolt head. The plan calls for 1.25" recess -I've made mine 1.5".
    The area under the fittings needs to be packed out to 7/8" : complete back side was initially packed already by 1/16" ply vertical web, so the front side needs to be packed out with 1/4" spruce and 1/16" vertical web ply on top thus we arrive at 7/8" total wood width at that point under the fittings.
    This lamination process made what looked to be a skinny 1/2" spar to be a very solid structure one that will support the wing while folding.

    . P1010529.jpg
     
    Last edited: Jul 29, 2014
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  5. Jul 29, 2014 #125

    Abraham Leket

    Abraham Leket

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    DRW9-Root Rear Spar Fittings: we construct (4) C fittings and (4) C1 fittings (cabane pick up) from 1/8" 4130 sheet fit each set individualy also mark each fitting and tag it to form starboard and port sets.
    The Pivot bars are not drilled yet- we have to assemble the sets (right thumbnail picture) and only then we cut (2) rectangle 3/4" bars, insert each in between C's fittings and drill through C1 and C pre made 1/4" matched holes -thus we achieve 100% fit.
    The (2) pivot bars are not yet horizontally drilled to accept the 3/8" pivot bolt-this task can wait for the outer wing construction stage.
    Note in left thumbnail picture- the complete starboard set with pre 1/4" construction/assembly bolts and the blue dot is where the 3/8" hole will be drilled later. The whole set calls for (20) 1/4" holes to match 100% (each fitting each side plus the inner bar) so.. double check before drilling. View attachment 33512 View attachment 33511
     

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  6. Aug 2, 2014 #126

    Abraham Leket

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    Root main spar to fuselage alignment (DRW10) : I would call this a critical alignmet and still put it mildly. The whole wing depends on this critical stage and we have to use scaffolding to adjust the angles with relation to the fuselage datum.
    We start by leveling the fuselage 100% with the horizon-check stabilizer and firewall to make sure its leveled.
    We start with the construction of the 3/4" 4130 tube front cabane struts and insert the 3/8" bushing ONLY in the top section where it connects to the root main spar cabane pickup fittings.
    next we insert wooden shims under both lower fuselage cabane pickups (F3) DRW10 (see picture 1) in order to align the cabane 1/2" end (future point to be drilled) lower 1/4" hole -with the fuselage pickup 1/4" holes and mark with a Sharpie the hole position on the lower cabane. The fuselage at this point converges so it is wise not just to drill at 90 degrees- check on job and do not drill yet-we have to check alignment first.
    We now position the main root spar with its (2) cabanes on top of the wooden shims -using any scaffolding method you find to support this rather heavy root spar and keep it steady (see picture 2,3).
    Now we can start measuring the angles (cabane 90 degrees to the fuselage top longeron and mutual middle datum fuselage/root spar and root main spar 100% leveled with the horizon).
    I've hang a nail with a fine thread to the root spar middle point to achieve that middle mutual datum- old method but potent...(see picture 3 and tilted picture 4).
    If all angles and datum match and most important- the main root spar is 100% leveled with the horizon-mark the cabanes (port & starboard), dismantle all, drill the lower cabane struts, insert the bushings and braze all cabanes bushings top and bottom.
    After the cabanes cools discard the wooden shims ,re-assemble the construction again- and re-check all angles. (to be continue)
    P1010543.jpg P1010544.jpg P1010541.jpg P1010542.jpg
     
    Last edited: Aug 2, 2014
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  7. Aug 4, 2014 #127

    Abraham Leket

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    DRW10-Drag Struts fittings: next in the process of stabilizing the root spar is to introduce the drag struts-and for that we need to produce (2) items- pair of drag link fitting and pair of drag end fitting.
    The link fitting is a 1/8" 4130 tang bend to 130 degrees and 1/4" drilled and conected to the root cabane pickup.
    Next item, the 5/8" 4130 end fittings, require any grinding tool ( I've used a side grinder and a steady hand) to carve the 3/16" channel needed for the drag link to get in.
    Took about 1 houre to make each peg, and 30 minutes for each drag link (to be cotinue).
    P1010545.jpg
     
    Last edited: Aug 4, 2014
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  8. Aug 5, 2014 #128

    Abraham Leket

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    DRW10- Drag Struts: The 5/8" end fitting is 3/16" drilled and a steel peg is inserted and hammered to a nice mushroom- both peg's ends (picture 1). Welding fitting/tube will follow.
    The drag strut is now mated with the front pickup fitting- do expect difficulties due to the fuselage convergence-drill the strut's front end (for its bushing) at an angel (fit on job).
    Picture 2-scaffolding is now removed- the main root spar is now super stable and ready for its center ribs.
    P1010550.jpg P1010548.jpg
     
    Last edited: Aug 5, 2014
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  9. Aug 7, 2014 #129

    Abraham Leket

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    DRW2 Center Section Root Ribs: The rib jig I've costructed fits in general all 3 type of FRED's rib : Root rib, center section rib, general rib.
    The only adjustments needed in the jig is the positioning of the diagonals and uprights within the rib i.e: the clearance for the main and the rear spar fittings.
    In the picture- center section root rib in the first stage of construction- upper and lower formers are dry bend inside the jig (with the friendly persuasion of a plastic hammer).. both rear ends are glued and the diagonals are shaped. This process takes about an hour. (to be continue)
    P1010551.jpg P1010552.jpg P1010554.jpg
     
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  10. Aug 8, 2014 #130

    Abraham Leket

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    DRW2- C/S root rib Gussets; I've made mine from 3/32" for (2) reasons- First its much stronger than 1/16" gussets but
    mainly due to a mistake I've made -cutting the gussets from 3/32" leftover instead of 1/16". So.. lets leave it as such- much stronger- what a wise decision that was.
    P1010556.jpg
     
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  11. Aug 13, 2014 #131

    Abraham Leket

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    DRW8-adjusting the C/S root rib: now that the C/S main spar is secured with the drag struts to 90 degrees we can adjust and glue the outer root rib to 0:0 level with the fuselage datum (fuselage front top longeron).
    Note that the rib datum is from the bottom trailing edge to an imaginary point 2" ahead of the main spar- and for that we insert a 1/4" shim under the (picture left side) measuring wooden bar (with the red bubble leveler at exact 0:0 on top) to achieve that straight datum line from the rib trailing edge to the rib datum 0 point of the GOT525 (imaginary point 12" from the full rib leading edge -or-2" ahead of the spar).
    The rib is light enough (300 grams) to sustain itself without support from the rear.
    24" clamp holds the rib intersection with the spar while glue is drying (to be continue).

    P1010557.jpg
     
    Last edited: Aug 13, 2014
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  12. Aug 13, 2014 #132

    Abraham Leket

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    Im postig JIC usefull comment:

    Fred #528
    Abraham, looking at your pictures in your construction log, I notice in the on titled DRW-10 Drag strut fittings that you had brazed the tube, using brass rod.

    If you are using 4130 tubing it is not recommended to braze it, the brass will get into the grain of the tube and when it cools it will expand causing cracks.

    If you are using just plain steel tubing your ok.

    I just brought this to your attention, in hopes that it may save you some grief later on.


    jic


    My answer : very good point- the brazing is on the 1020 steel bushings inside the 4130

    tube to prevent the bushing side movement - but point well taken !!
    Thanks JIC !!​
     
    Last edited: Aug 13, 2014
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  13. Aug 13, 2014 #133

    Abraham Leket

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    Another shot at the adjustment with a close up on the 1/4" wood shim:
    P1010558.jpg
     
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  14. Aug 16, 2014 #134

    Abraham Leket

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    Now that we have the so called Pivot rib lined up with the main spar and 0:0 with the fuselage datum we can dismantle the main spar with its front and drag struts and all the fittings and place the bare wood spar on a flat surface with its aligned and glued pivot rib face upward.
    All is left now is to place the other 2 ribs aligned with the pivot rib. The pictures depicts the second and the third rib positioning.
    DRW 2 calls for 17" from trailing edge to the back spar and we just tack glue them- the top and bottom gussets and top and bottom ply covers will secure the ribs positioning (in the future process).
    P1010559.jpg P1010561.jpg
     
    Last edited: Aug 17, 2014
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  15. Aug 18, 2014 #135

    Abraham Leket

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    P1010537.jpg P1010536.jpg P1010560.jpg DRW13- Center Section aileron crank The main C/S spar is now on the table and we can install the crank . I've used steel pins instead of the aluminum rivets suggested in the plan (see thumbnail picture). The bubbin connector was slightly modified- see upper right picture. P1010533.jpg
     

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    Last edited: Aug 18, 2014
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  16. Aug 20, 2014 #136

    Abraham Leket

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    Fuel tank construction but first- this article by Rick Galati RV-6A "Darla" his RV6 has an enlarged multi-cell version of our single fuel cell FRED - both are identical in shape and construction method. Go ahead Rick :
    Thank you Abe for adding my article into your humble FRED construction log !:)
    Sealing the tank
    Working with proseal is no big deal.....really. It continues to rate right up there with canopy cutting as a chore many builders seem to dread with a vague sense of impending doom......shadows of ill-defined personal perception overwhelming the clarity of knowledge and reality. Who starts these wild overblown horror stories? Overrated piffle. The stuff of wasted worry.
    For years I worked with proseal, often daily and for weeks at a time. Even after many years of working with a material used in far more applications than just fuel tanks, I still had to attend 3 days of sealer school to satisfy customer requirements for training when I did a stint on the C-17 program. The cockpit and nose section of the giant cargo plane is produced in St. Louis. It is proseal that makes pressurization possible. It made some sense to retrain when assigned to the C-17 program because the enormous size of the pressure vessel demanded proseal be applied precisely and application requirements were somewhat different than the routine techniques we commonly employed on the F/A-18 Hornet. Interestingly, those persons skilled in icing a cake performed better with a filleting spoon than their polysulfide-challenged co-workers when requirements specified spreading proseal evenly over a surface without any interruptions or other defects. In the self-interest of limiting the mess to an absolute minimum and keeping my clothes unstained (rarely successful since I refused to wear an apron), I did manage to absorb a few helpful tricks over the years. Admittedly, most of the time I used a pneumatic Semco to apply the stuff, but the use of a Semco sealant gun does present a logistical nightmare for the average homebuilder because it can accept a dizzying array of accessories including various sized tubes, nozzles, spreaders, extentions and such. Last but not least, the stock of limited shelf life sealer was mixed daily and manually stuffed into appropriately sized tubes by the friendly folk working the neighborhood sealer crib, stamped with an expiration date, then distributed plantwide into dozens of stategically located 40 degree below zero freezers for shop use. That was the way things were done for decades until a new age of economic fashion swept the nation. Not too many years ago, the powers-that-be decided proseal mixing should be subcontracted out to distant strangers, layoff notices soon followed, and the proseal mix is now shipped in from afar and stored in new 80 degree below zero uberfreezers!
    Fortunately for the RV builder, the job of sealing a bit easier with the introduction of this handy device, essentially a caulking gun- I recommmend using one, if possible. Such a device sure beats using a common alternative a homebuilder has traditionally been reduced to using...a paper cup and a popsicle stick or tongue depressor. Still, the device is nice but not really an essential tool.
    As for proseal itself, if you get the stuff on your clothes...forget it. Nothing out there will remove proseal without also discoloring your shirt or pants. I take that back. Methylene chloride will "sometimes" work (depending upon the fabric) but its dubious use is best served for a much more noble cause...to decaffinate coffee. Otherwise its just too toxic a chemical and not worth the risk to health from needless exposure. Prior to using proseal, rub some barrier cream or lotion into your skin to more easily remove the stuff from your hands after a sealing session. Wear a pair or two of latex gloves anyway. You can peel the first pair off as required.
    Tank Assembly:
    When I assembled my leak free fuel tanks, I proceeded exactly as I would at work. There is no compelling reason to wallow around in wet sealer needlessly! I would commonly apply the proseal to the mating surfaces of the parts (called fay-sealing), 100% cleco the assembly together, then allow it set up somewhere between tack dry and full cure. That's it. Walk away. Upon returning to work the next day or even better....after the weekend, I would then remove every second or third cleco from the assembly, wet install and shoot the rivet, then repeat the process over and over again until all the rivets were set.

    [​IMG]

    The above pre-digital pictures make a poor attempt to illustrate the procedure I used on my 6A fuel tanks. First, after roughing the local fay sealing surfaces with maroon scotchbrite and thorough cleaning with MEK, the ribs were fay sealed and secured to the skin by 100% clecoing into place. I insured adequate squeeze-out (smoothed into an uninterrupted fillet seal) existed around the ribs and skin (and previously installed stiffeners) without any voids whatsoever. Session complete. I felt no need to have extra sealer arbitrarily slopped all over the place as a sort of voodoo talisman employed to ward off leak demons. In my mind, excessive and weighty sealer needlessly laying about in perpetuity simply displaced that much more fuel the tanks would otherwise hold. A day or so later, the rivets were wet installed by first removing the clecoes from alternate holes. When all rivets were finally set and while I still had interior access, AND to further insure against leaks, using a Q-tip or a toothpick, I swirled a dollop of sealer around the shop head of each rivet to encapsulate it to its dimple. Next came attaching the rear baffle to the tank skin. As shown, I routinely 100% clecoed and clamped assemblies together. I then allowed the freshly (fay) sealed assembly to set up overnight before moving on to and completing the final riveting. This procedure greatly reduced mess and bother when I worked with wet proseal during this interesting phase of construction. Correctly applied, proseal is truly a tough and awesome material.

    The photos below were were added on 01/07/09 to more clearly illustrate the procedures I outlined in the original posting. These are detail photographs of the RV-8 fuel tanks I assembled in January '07 following the exact same procedures. Filled with fuel for some months now and like my -6A flying since '05, no leaks have been detected.

    [​IMG]

    [​IMG]

    As in all aspects of our personal construction experience, we should strive for perfection knowing we will never really achieve it. Prosealing need not be the nightmare scenario some would have you believe. Far from it. There are more pleasant sheet metal tasks to do...sure...but...whoever said building an airplane was not going to be a challenging experience from time to time?

    Rick Galati RV-6A "Darla" 124 hours
    [HR][/HR]
     
    Last edited: Aug 20, 2014
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  17. Aug 20, 2014 #137

    Abraham Leket

    Abraham Leket

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    DRW21-Fuel tank parts: Fritz (from the lovely NIERRH projet here) was kind enough to draw FRED's parts using a nice 3D program and on doing that he solve my dilema on shaping the tank sides. Thats modern solution to a 50 years old problem...let these fine pictures present the parts needed.
    Notice the flip of the edges to face outward- GREAT idea Fritz. This solves many fuel related problems mainly 100% sealing for a long time. Also- 7" inspetion panel that allows internal tank inspection and maintenance- another one of Fritz's good idea.
    Thanks Fritz- you are an asset to me!
    Tank%20Explode.jpg Tank%20Rib.jpg Tank%20Rib%20Front.jpg Pro%20Seal.jpg
     
    Last edited: Aug 20, 2014
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  18. Aug 26, 2014 #138

    Abraham Leket

    Abraham Leket

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    DRW21-fuel tank brackets bottom brackets from 1/8" 4130 since they take most of the load. Upper bracket 3/32" 1020 mild steel.
    The main and rear spar coated with varnish and with a Qtip soaked with varnish-the 1/4" fitting's holes receive their varnish dose inside.
    Note that I'm still using assmbly bolts- AN sets are on the way from SA.

    P1010565.jpg
     
    Last edited: Aug 26, 2014
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  19. Aug 26, 2014 #139

    Abraham Leket

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    Waiting for parts to arrive from the USA and in order not to stay idle I took the task of shaping 3/32" ply to form the front instrument fairings. The 3/32" ply gave a fight- but finally yield to my clamps & staples.
    P1010564.jpg
     
    Last edited: Aug 26, 2014
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  20. Sep 12, 2014 #140

    Abraham Leket

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    Wheels & breaks : Azussa 8" and 4.5" break drum and break assembly plus matched tires and tubes -all purchased as a complete set from AS to match FRED's 5/8" axel ( if you dive into Azussa Catalog and try to figure out whats needed -chances are you'll end up with an unmatched sets- watch the wheel ball bearing inner diameter before ordering- FRED could handel 3/4" axel too.
    Before assembly- a 4.5" 14G 4130 round diameter steel flanges were welded to the axel carry tubes (see picture 4) to enable the breaks to connect firmly to the "A" frame with (2) 1/2" bolts (the breaks plate comes pre-drilled to accept the bolts)-see picture 3 bottom plate -a locknut is seen.
    You also need to drill a 5/8"-3/4" hole in the plate to allow the break lever pivot bolt to exit.
    At this point when the back plate is welded to the axel carry tube- it is easy to perform a final alignment test to make sure both plates are 100% parallel to each other and 90 degrees to the firewall.
    Finally-picture 2-(3) 18G triangles were welded to each of the "A" frame intersections and 3/16" drilled to enable both "A" frame to be covered with 1/4" ply to smooth the airflow around the tubes- small addition to the total "old school" look.
    P1010567.jpg P1010566.jpg P1010568.jpg !cid_D7AD36DC-454D-444C-A2C0-CBE91D5CB63F.jpg
     
    Last edited: Sep 12, 2014
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