FRED #528 construction log

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Abraham Leket

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The (2) crank assemblies are a bit harder to weld since the amount of material (or should we say-lack of material) calls for a very carefull TIG welding- in any case-welding bits brazing any time- and I prefer TIG to brazing, again- carefull not to melt the entire assembly..:shock:
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Abraham Leket

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The inspection door on the port side comes in handy now-when the crack is connected to the elevator horn with a loose assembly bolt and positioning trials begins : the elevator and the crank connecting rod should move freely- we find the spot and mark it for drilling.
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Abraham Leket

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The plan calls for initial 4.5" from stern post- mine came 5"+ so drilling commenced with my trusty drill guide set 10 degrees off to compensate the tail longerons convergence. Clamps used to secure the drill guide to the surface (see picture). Note port inspection door wide open- sure pay its dividend now when accessability is needed.
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Abraham Leket

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Once we are satisfied with the rear elevator crank performance i.e.: no contact with rudder post safety bolt and rudder hinge bolts we are ready to cover the rear tail box with top 3/32" ply and we also grind a 1/2" channel for the rear crank push rod clearance plus gluing the incidence 3/4" spruce bar (its location-the stabilizer sub spar contact location with the top 3/32" ply).
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Abraham Leket

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Turtle deck construction: begins by gluing a cross 3/4" spruce as depicted in DRW4 (the cross section detail).View attachment 30120 Next we construct the back seat 1/16" ply member (I've decided to construct the back seat 1/16" ply in 2 pieces-top and bottom). Its top section ( depicted here) will hold the safety belts steel fittings and the clear pine 3/4" fillets (DRW5). The back seat bottom section with its inspection panel will be constructed much later –right now it will only interfere with the elevator-stick measurements and adjustments and there is no reason to construct it right now. BTW-The 2 back seat sections (top and bottom) intersects on the cross 3/4" spruce bar (see DRW4)View attachment 30122
 

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Abraham Leket

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Turtle Deck Construction (Cont.)- The first former in the deck is the 9" seat back, next is the locker rear wall- 7+7/8", these 2 points give us the angel needed for formers #3 and #4 by placing an 1/2" stringer on top (see picture). We have to keep in mind that the top stringer should cover half of the stabilizer height (as it rests on its incidence bar) I've measured 3.75" (see ruler) . So.. "on the job" play is called to determine #3 and #4 height above the fuselage cross members. Note that the former bottom lip -3/4" should be added to that height such that the former is glued to the cross member and still has the correct height for maintaining an even angel of the stringers. Also take into account that the stringers will sink 1/2" inside the formers.
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Abraham Leket

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Turtle deck construction (cont): now that all 4 formers are shaped we first drill the decking fittings 3/16" holes in #1 and #2 formers (see picture).
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Abraham Leket

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We now move to DRW5 for the decking fittings: I use 4130 16G throughout. Note that the safety belt fittings are 3" wide to accept the modern safety belts 2.5" width (in the plan its 1.25" wide- wonder what safety belts they had back then-1"??..) . I've also bend the edges so that the fitting edge will not cut into the shoulder belt fibers. Also note that I keep the pairs attached -they are identical twin all the way from drilling them together (one on top of the other) to positioning.
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Abraham Leket

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the main deck fitting ("carry through") is the 1/2" tube in between #1 and #2
P1010354.jpg
Instead of using 1/4" bar to secure #2 to the fuselage (DRW5) I'm using 4130 16G strips- same strength same weight but without welding.P1010355.jpg
 
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Abraham Leket

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Now that the fittings are adjusted- we can remove them until the final stages of FRED contruction and we can now notch the stringers positions on the formers. Best way is using a router with 1/2" router bit (see picture).
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Abraham Leket

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Turtle deck-end: The plan calls for top 1/2" stringer only and the whole deck to be covered by 1/32" ply. I've seen some FREDS with full stinger deck- I've liked it- gives FRED that Hawker Hurrican ww2 look...
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Abraham Leket

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Seat construction: Most important thing in seat design is not to try to" reinvent the wheel"-your alternative design "front office"-whatever it might be could collapse in a 2G bump and jam the elevator- and its game over..So.. Eric's original design uses multiple 3/4" and 2" blocks with 1/16" gussets and it’s a "drop in" 1/4" ply for your buttocks-works great for 50 years. I've reinforced the foot rests and used 5/16" ply for the seat to take care of my humble Weight-220 Lb. Other than that-all pictures -straight from DRW 4 cross sections D (back) X (middle) and E (front). P1010367.jpg
 

Abraham Leket

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Front Cabane Fitting (DRW4 , DRW10): As with all other metal part I'm using 4130 1/8" sheet and bar to handle this important sub-assembly. The plan (DRW4) depicts the fitting at 90 degrees to the cross bar- not so when you build the short nose version-the top longeron converges at that point -and it is wise to cut the bar at an angel (in both ends) to compensate that deviation before welding the inner fittings.(check the picture and close look at the bar and its inner fitting to recognize that "toe-in" ).
The 3" metal gussets in the cross bar calls for filling the inner fitting weld flat so that the gussets will seat tight against the bar - before all 4 gussets are welded. P1010370.jpg
 

Abraham Leket

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Undercarriage A frame fittings (DRW11) : This task is a little more complicated since we enter an area of geometry and ground stability.
Eric-the designer- hints that moving the undercarriage A frame front tube 2" forward will eliminate problems associated with using breaks and getting into a "nose over" but this modification calls for (4) universal joints install in the LG spring shaft- a $400 affair if you choose to purchase the joints in the open market.
My personal opinion-if your weight is 180-200 lb you are not even close to a nose heavy situation - so .. we can dispense with this modification and the universal joints issue.
Next- the fittings are located right where the fuselage converges and creates more than 1.5" difference in the A frame back-to-front fittings that should be 100% straight and level with each other (since they act as hinges to the A frame) . The plan gives 1/2" difference in the fittings (back Vs.front) to compensate this converge -not enough in my opinion but I went with Eric's numbers in the plan-1/2". When the A frame will be installed on the fittings we will see if we will re-do this section again...The picture depicts DRW11 fittings.
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Abraham Leket

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P1010384.jpgWhen welding the fittings (as DRW11) it is wise to use this simple jig made out of loose nuts (all metal anchore nuts in my case) and 1/4" bolt to maintain even welding and elignment . You simply "dial-in" the needed 1 +1/4" by moving the bolts and you tack the fittings onto the base. Once the weld cools-we simply remove the jig and we get a nice and aligned fitting.
Just make sure the nuts are not lock nuts- the temperature of the fitting when welding is 4000F...


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Abraham Leket

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Scenes from the shop: I'm getting questions if I'm using laser cutter for the metal parts and how do I weld them. I take it as a complement that the parts looks like being laser cut- the answer is very simple- all you need to cut Fred's metal accessories is a simple side grinder-period. The welding can be done using either a TIG machine ($280 in EBay) or Oxyacetylene set (mine in a 50 years old set with Victor #1 tip and 40 CF bottles). I do reccomend the TIG- after a quick practice you will turn out weldings "aviation quality". The Oxy-Acy is for old timers -takes years to do it right-but we love it..Takes me back to the Stearmans and Texan days..

Cutting parts ( now you see why a nose heavy situation is not an issue with me...;)):
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welding the parts:
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