FRED #528 construction log

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Abraham Leket

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The general description of FRED all wood single seat 370 kg TOW/ 60 HP VW engine can be found in CLUTTON FRED site in YAHOO.
I will start righr away : the construction of 2 EAA chapter 1000 tables needed to construct FRED: this is 250 cm x 80 cm main table and a smaller 150 x 60 -combine the two gives 400 cm construction platform to build
FRED:

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Abraham Leket

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The process of scarfing using a home made jig gives 1:15 ratio (to 3/4" you need 11" scarf) and I use resoursinal glue (cascophen) to join the scarf As for the glue -the ratio mix- 4 parts resin to 1 part powder by weight. I try to use this superior glue as long as I have more that 70 degrees in my shop. If it will drop below-I will use T88.
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Abraham Leket

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Never felt comfortable with mixing T88 by volume. I mix mine by weight using the formula 0.836 unit Hardner for every 1 unit resin. Worksheet table lets me pure resin (right column) to a cup standing on precision (0.1 g to 500g) scale- I then pure the hardner until I hit the total mix weight (left). This method insures that you will never end up with surplus resin or hardner wandering which batch was bad (please God..not in the firewall...)
 

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Abraham Leket

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Fusalage starboard side finished- Resorcinal Cascophen used on uprights where tight fit was achieved. T88 was used on the diagonals -the 4 cuts-2 on each side of the diagonal made it very hard to arrive at tight fit and I needed a filler to close all sides 100%. After drying the epoxy shrunk a little-so a second round of small T88 mixed with Microbaloon was used to fill all cavities to a smooth sufrace.
 

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Abraham Leket

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Shaping the FRED fuselage is relatively easy IF you flip the sides upside down and you lay the flat upper longerons on the table. All measurements are taken and marked directly on the flat longerons and you don’t need to guess locations "up in the air" so to speak.The plan calls for 22 inch cabin width - much to small for my figure-so I've taken the liberty (given to a 100% project)-and made it 24 inch.( Let see you do it on 51% project...).First step is installing the crossovers at the fuselage widest points and from there- we will later on bend the longerons to the firewall (14 inch) and to the rudder post (3 inch).The crossovers and the clamps will assure that the widest points will remain so- in the bending process.
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Abraham Leket

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Gluing the 14 inch firewall cross beams requires a delicate process- jig blocks were used to mount the bottom cross beam exactly on the center line mark and press it with jig blocks to prevent movement. The upper cross just follows the natural line of the lower cross beam and both receive a mild press from 24 inch clamps and both were glued to the longerons without excessive pressure in order not to starve the joint from T88. Another view is the whole fuselage- follows the center line- from firewall to rudder post- hopefully it will pass a high humidity winter and stay that way:ermm:.
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Abraham Leket

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The plan calls for "hardwood" as the rear wheel spring base. I've picked Teak wood-certainly a prime contender in the Janka Hardness Scale-twice as strong as spruce (and 40% heavier-almost 380 grams).To counter it I need at least 2 Kg extra weight in the forward section.:ponder:.
Cutting and shaping it is another matter-the battle raged for an hour using a band saw and a hand saw. Pilot holes for mounting the spring were done now in a vertical drill. I really do not trust my aim in a hand drill- better drill straight holes before mounting any item that needs to be drilled on the fuselage. P1010198.jpgP1010199.jpg
 
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Abraham Leket

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The plan calls for 25 feet of 3 inch spruce for all wood blocks and boards- well-that was in the early sixties when it was design- today a 3 inch by 3/4 inch spruce costs $9 per foot.:mad2:
I've decided to use Carolina Pine-it's strong-and slightly heavier than spruce-about the same weight and hardness as Douglass fir (which is considered the second best wood).
Note the pre-drilling of the Rudder Pedal stand/Front Wire Fitting. (6) 1/4 holes is advised and better do it on a vertical drill before gluing the plank up front. BTW- got the Rudder set in Ebay (from some light sea-plane that crashed) for $25:ban: P1010200.jpgP1010201.jpg
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Abraham Leket

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This picture dissolves the plan haze- out of the bottom front fuselage multi cross (8) members:(Direction: from firewall to rudder ): 3/4 inch firewall cross member , 3/4 ince cross member, 3 inch rudder and front wire brace base (I moved it 1.5" forward to fit my legs), 3 inch forward stick and front wheel base, 2 inch back stick base, 3 inch rear wheel base, 3/4 inch mid seat support cross, 3 inch rear wire brace base.
I've glue all with resorcinol Cascophen for extra strength. As mentioned-as long as I have good fit and temperature above 70F (20C)-I use resorcinol
Some might think its an "ols school glue"-but nothing bits its strenght- not even T88 epoxy.
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Abraham Leket

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Wood blocks are added now-use cardboard patterns to fit-then cut the wood with the grain direction-as plan.
If tight fit is not achieved-use wood shims (in the same wood grain direction) to close up to 1/32 inch gaps. If more-discard and do it again..
The wood blocks section demands time and carefull filling-it took 8 hours to fit all.
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Abraham Leket

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Stern Post is glued to the wood insert (in between 4 converging longerons). The area need to be flat in order to give T88 a chance to make 100% contact (no miracles-T88 needs flat areas to be strong).
Pre drilled 3 pilot holes (in a vertical drill) and application of Wax with Qtip to prevent T88 from curing inside the pilot holes-cured T88 will deflect the right size drill bit later on -if measures are not taken now).
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Abraham Leket

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Gussets time-The plan calls for installing some gussets prior to bending the longerons- in my opinion the glue in the gussets and the longerons will only stiffens
the bending.
Anyway-I've choosen to do it now-after all wood blocks are in place. I've seen some pictures of FRED builders who glue gussets prior to the wood blocks- BIG mistake in my opinion since internal glue spillovers will make the fitting of the block to its gusset much harder.
The edge of the gusset (they are razor sharp) needs to be beveled so it would not rip the Ceconite cover-later on.
The pictures correspond to the outside 1/16 inch gussets in back section (seat support to tail post).
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Abraham Leket

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Normally I would not post another gusset session here-but I have found out that Eric Clutton (the designer) did not leave an area to glue the Ceconite cover in the port side inspection door-so I have made it-for you to decide.
Another issue is the locker floor ply (which also serves as a giant gusset) - unless you carry small change-it can be done this way using regular 4 mm ply (with relief holes due to its extra weight).
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Abraham Leket

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I've decided to strength the cockpit rims due to the fact that to enter and rise from the seat requires leaning with all the weight (230 Lb) on one or two upper longerons-sure hate to hear a crack-so.. a simple 3/4 square and 3/32 gusset on both sides will give some confident without too much of a weight penalty (plus a handy base for the throttle quadrant on the left side). This additional strengthening is optional of course.
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Abraham Leket

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The last gusset sets to be constructed is the tail 1/16 inch large side gussets and the tail bottom 2.5 mm ply gusset.The starboard 1/16 ply gusset can be glued right away but before dealing with the port side 1/16 inch gusset –an inspection panel door must be constructed inside the gusset-with hinges and an appropriate lock PRIOR to gluing the gusset to the side longerons and uprights. Such construction will be nearly impossible to do -if you choose to glue the port gusset without constructing the panel first .This inspection panel is extremely important feature in each and every Pre-Flight procedure since it reveals to the inspecting pilot the condition of the elevator push rod Aurora bolt and the tail elevator swing arm. So- build the panel in such a way that it will perform thousands of trouble free open/close Pre-Flight inspection cycles. Balsa doublers were glued inside of the 1/16 inch panel to give it some rigidity and prevent warping which is quite common with such thin ply-specially in high humidity /wet environment. I've chosen to purchase the hinges from a store that specializes in Radio Control models-they carry all sort of light-but strong hinges (such as the "bomb-bay" type hinge set depicted here in white).The lock mechanism is a very light aluminum door latch purchased at local hardware store-it will be riveted to the panel door-after paint and that’s-much much later (but its rivet size holes were drilled now in a vertical drill).BTW- the tail bottom 2.5 mm ply gusset can wait –after constructing the stabilizer. P1010226.jpgP1010223.jpgP1010224.jpgP1010225.jpg
Final view of the basic fuselage minus the turtel deck construction which at this point will only interfere with the alignment of the next item to P1010227.jpgP1010228.jpgbe construct-the stabilizer P1010229.jpg
 

Abraham Leket

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Tail flying surfaces: we begin by cutting the two 4.25" by 84" spars (rear stabilizer spar and front elevator spar are identical). The narrow edges (from 4.25" to 2") were cut using vertical saw and a great $50 tool called Roller Stand (ebay has many to offer) which acts as a third hand. We cannot really handle 84" length planks without it- it’s a MUST tool.



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The elevator spar get its (6) 3/16" elevator control horn holes-in a vertical drill (what else..;)) to be duplicated to its 4.25" by 46"doubler later on and I've also made 4 pilot (undersize) hinges holes-to be duplicated later on to its twin brother- the stabilizer rear spar. The 4" by 3/4" cut in the elevator spar (bottom recess) is also done at this point- no way you can do it -once assembly begins.

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Abraham Leket

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Mark this point in the log where a pint of T88 and a pint of Cascophen glue ran out. Better go for a quart of each at the beginning of the project to fully construct the fuselage and the tail section and get some left over-to begin the wing section. Speaking of left over- the picture depicts the elevator doubler that was made out of 3/4" longerons bits left from the fuselage construction- with spruce prices now days-we should get the most out of it.
BTW-Eric Clutton (the designer) wrote me the other day that in the sixties in England-he got his Sitka Spruce from a ladders (!!) producer that otherwise probably would have used the scraps to run the boilers for "A cuppa tea for the Lads"…Yes-in only few years nature is practically diminishing before our very eyes-no more to give brothers..
.
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