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Twisted Hobbys Crack Laser, with a few new build tips

Discussion in 'TwistedHobbys.com' started by cwojcik, Apr 4, 2013.

   
  1. cwojcik

    cwojcik 70cc twin V2

    299
    2
    16
    Hey guys, I thought I would post a little build of the new Crack Laser. I'm extremely proud of this airplane, and I think you will all love it! In this build I will incorporate some new durability tips we have learned with these airplanes, which are applicable to any EPP foamy. I will also post a separate article on these new techniques.

    First, lay out your tools and supplies...a square, Phillips and flat-head screwdrivers, tweezers, CA, the ubiquitous Welder glue, hobby knife with fresh blades, wire cutters, and new for this build: Blenderm tape. Also recommended but not shown is a good set of weights and some parchment paper.

    M1380006.jpg

    Also pictured is the Twisted Lite Power Combo including 1750 KV motor, 6 amp ESC, 8x4.3 GWS props, 2X CS-40D and 1X CS-90D servos. Also some 360 mah batteries.

    M1380008.jpg

    Fuselage parts

    M1380010.jpg

    Wing parts

    M1380012.jpg

    Tail parts, small foam parts, wheelpants

    M1380017.jpg

    Hardware pack

    M1380020.jpg

    The very first thing you should do is fold each hinge back 180 degrees and put a weight on it for a few hours or overnight. This will make the hinges more supple and really help take load off of the servos.

    M1380023.jpg

    Next let's reinforce the hinges. First cut a small piece of Blenderm tape.

    M1380026.jpg

    Put a small bead of glue near the end of the hinge line.

    M1380029.jpg

    Lay the piece of tape on the glue, sticky side down.

    M1380030.jpg

    Flatten it and press the glue out to the edges of the tape.

    M1380031.jpg

    You can use your knife like a rolling pin to get it perfectly flat.

    M1380033.jpg

    The result is an almost invisible reinforcement that won't break. Do this at the ends of the elevator and rudder, and the root and tip of the aileron. There is no need to do it near the inboard counterbalance.

    M1380034.jpg

    Now let's assemble the wings and horizontal fuselage. Lay out a piece of parchment paper (note: this should really be the same size as the wings).

    M1380036.JPG

    Test fit the wings together and make sure everything lines up. We will do this assembly upside-down.

    M1380037.jpg

    Lay a bead of Welder glue on the mating surface the wing...

    M1380038.JPG

    M1380041.jpg

    ....press it together to wet both surfaces....

    M1380043.jpg

    ...then pull it apart and let it tack up.

    M1380045.jpg

    After the glue is tacky but not wet, press the wings together. It will grab tightly.

    M1380047.jpg

    Cut out the 4 ribs.

    M1380049.jpg

    M1380051.jpg

    Find the spars...they are the long carbon tubes.

    M1380053.jpg

    Clean out the slots for the spars with a sharp knife.

    M1380056.jpg

    This is how the spars go in...the short spar goes in first, the longer spar is on top. The bumps on the ribs point out of the bottom of the wing.

    M1380064.jpg

    Test fit the spars and ribs in to make sure everything fits well.

    M1380068.jpg

    Spread some glue in the slots for the spars and ribs.

    M1380071.jpg

    ...and then install the spars and ribs. Wipe up any glue that squirts out.

    M1380074.jpg

    Weight down the assembly and let it dry completely.

    M1380077.jpg

    M1380069.jpg

    Now let's do some optional reinforcement. Lay a bead of glue down across where the wing meets the fuselage...do this in four places: the trailing edge and the leading edge, on both sides.

    M1380082.jpg

    Now lay a piece of blenderm over these strips of glue. Press it down just like you did with the hinges.

    M1380084.jpg

    After you repeat this on all four corners, you will have a much stronger fuselage. I find that these models tear here a lot but this really prevents that.

    M1380085.jpg

    Glue the stab and elevator on the fuselage with the same procedure as the wings.

    M1380087.jpg

    M1380091.jpg

    M1380093.jpg

    M1380095.jpg

    Add a fillet of glue at the corner of the stab and fuselage. This will help with durability.

    M1380097.jpg

    Now it's time to install some servos. Plug in all of your electronics and test them.

    M1380099.jpg

    Here's a trick we have found...spread some glue thinly in the servo cutout and LET IT DRY COMPLETELY.

    M1380100.jpg

    Do the same on all mating surfaces of the servos, letting them dry completely. When you install them, you can pop them in and they will not move around at all. However they will be much easier to remove than if you had glued them in normally.

    M1380104.jpg

    Now let's install the aileron horns. Cut them out of the plywood piece and cut the pushrod guides out of the horns.

    M1390001.jpg

    Store the pushrod guides in the hardware bag...they are easy to lose.

    M1390002.jpg

    Clean out the slots for the aileron horns on the ailerons.

    M1390003.jpg

    Install the EZ connectors on the aileron horns.

    M1390004.jpg

    Make sure the screw hole is point out, away from the fuselage, so you can get to it with a screwdriver.

    M1390008.jpg


    Now pop in the aileron servo. You may need to gently pull the foam away to work it in there but it will go in.

    M1390009.jpg


    Do the same for the rudder servo.

    M1390010.jpg

    Power up the rudder servo to center it, then install the arm. You should also install the EZ-connector on the arm before you install it (not shown here).

    M1390015.jpg

    Test fit the upper fuse half on the wing and horizontal fuse to make sure everything clears properly.

    M1390013.jpg

    You will likely have to cut a small clearance for the aileron servo wire.

    M1390011.jpg

    M1390012.jpg

    Spread some glue on the mating surface of the upper fuse half.

    M1390016.jpg

    Install the upper fuse half...

    M1390019.jpg

    ...and make sure it is lined up correctly.

    M1390022.jpg

    Once the upper fuse half has dried a bit, hang it off of the edge of your bench.

    M1390020.jpg

    We can now install the elevator servo. Make sure it is centered, and install the arm and EZ connector. Pop it into the fuselage.

    M1390021.jpg

    We can now also the aileron arm. Cut it out of the wood parts.

    M1390023.JPG

    Find the round servo wheel for the aileron servo. The hub fits neatly in the hole of the arm.

    M1390024.jpg

    Add a little Welder glue to the surface of the round servo wheel and glue it onto the aileron arm. DO NOT LET IT DRY YET.

    M1390025.JPG

    Before the glue dries, center the aileron servo, and install the arm. Now, with the glue still wet, rotate the aileron arm until it's perfectly aligned. Now you can get full travel and perfect centering without using sub-trim. Install the screw (not shown).

    M1390026.jpg

    Weight down the wing and install the lower fuselage half. Test fit it with no glue to make sure everything clears.

    M1390027.jpg

    Then glue it on, and use your square to make sure it's all lined up.

    M1390028.jpg

    Check the alignment at both ends.

    M1390029.jpg

    Next, let's install the foam braces that keep the tail torsionally stiff.

    M1390030.jpg

    Trim the front of one of the braces off to clear the servo wires. Hang on to this piece.

    M1390031.jpg

    M1390034.JPG

    Glue them on carefully, keeping everything aligned.

    M1390035.jpg

    Next let's glue on the motor mount. Wet it with plenty of Welder glue....I have found there is no need to scuff it.

    M1400002.jpg

    And stick it on the front of the airplane, lining everything up carefully.

    M1400003.jpg

    Let it dry a bit. Now, time for another new reinforcement tip...first, smear some Welder glue all around the area behind the motor mount legs.

    M1400005.jpg

    M1400006.jpg

    Cut some blenderm strips maybe 2.5" long, and carefully wrap them around the motor mount and over the glue you just applied.

    M1400010.jpg

    M1400007.jpg

    Repeat on all legs of the motormount. This will keep the front of the plane from tearing off in a really hard crash.

    M1400011.jpg

    Open up the holes for the motor mount screws with your knife.

    M1400012.jpg

    Finally, find the piece of the foam tail brace you cut off for wire clearance, and glue it on at the front of the airplane. This will keep the nose stiff and add some reinforcement.

    M1400035.jpg

    Next let's assemble the landing gear. Get the plywood hockey-stick shaped pieces out of the hardware set, the T-shaped wheelpant mounts, as well as the short carbon axles, wheels, and flat gear legs.

    M1400014.JPG

    Drill out the axles with a 1/16" bit.

    M1400016.JPG

    Glue the wood part to the gear leg with a drop of medium or thin CA.

    M1400017.JPG

    M1400018.JPG

    Glue the axle to the other end of the wood part, repeat for the other leg.

    M1400020.JPG

    M1400022.JPG

    Now wrap the wood part and joints with thread. Anything will work; here I am using carbon tow but sewing thread is fine too. After it is wrapped add a drop of thin CA to the thread.

    M1400024.JPG

    Next slip the wheel onto the axle as well as the T-shaped wheelpant mount. Put a drop of CA on the joint for the wheelpant mount to secure it.

    M1400025.JPG

    Put the gear legs aside while we install the aileron pushrods...it will be easier this way.

    Find the stiff, round rods from the hardware pack, as well as two Z-bent wires, and two pieces of heatshrink tubing. Scuff up the wire with some sandpaper to promote good adhesion.

    Put a Z-bent wire on the end of each pushrod with heatshrink.

    M1400026.JPG

    M1400028.JPG

    Add a drop of thin CA where the wire protrudes from the heatshrink. It will wick into the joint and cure.

    Next put each pushrod in the aileron arm, and then flex the ailerons to insert the other end of the pushrod into the EZ connector. With everything centered, tighten the screws, and trim off the excess pushrod, leaving about 1/4" extra.

    M1400031.jpg

    M1400032.jpg

    M1400033.jpg

    With the gear legs prepared, let's install them on the fuselage. Find the plywood rectangle for the wood parts. There is a cutout on the lower fuse where the gear legs pass through; the rectangle goes between the gear legs at this point. Clean it out with your knife.

    M1400036.jpg

    M1400037.jpg

    M1400038.jpg

    M1400039.jpg

    After dry-fitting everything, pull it all out a bit, add some glue, and reassemble. Make a good fillet where the ends of the gear legs engage the fuselage (there are holes there).

    M1400040.jpg

    M1400041.jpg

    Now is a good time to install the elevator and rudder horns. These are different than the aileron horns but identical to each other. Pop them out of the hardware package and cut the pushrod guides out of them.

    M1410002.JPG

    Clean out the slots that are cut for the horns in the surfaces with your knife.

    M1410004.jpg

    Finally, glue the horns in with some Welder glue.

    M1410007.JPG

    Next we can do the elevator and rudder pushrods. These are the long carbon rods from your carbon pack. Attach the Z-bends to the rods with heatshrink and CA just like you did with the aileron pushrods, then thread on six of the plywood pushrod guides on each pushrod. Then, insert the Z-bend end into the horn, and push the other end of the pushrod into the EZ-connector on the servo.

    M1410008.jpg

    M1410009.jpg

    Next, carefully find the lasercut holes for the pushrod guides, and carefully glue them into the holes, being sure not to get any glue on the pushrod. You can use either Welder glue or CA here.

    M1410010.jpg

    M1410012.jpg

    M1410014.jpg

    Now trim off the excess pushrod length and insert it into the bottom of the fuse to make a tailskid.

    M1410015.jpg

    M1410016.jpg

    Finally, it's a good time now to install the SFG's and T-canalizer. The wing SFG's need to be split before they can be glued on...take care to make sure everything is properly lined up.

    M1410023.JPG

    M1410024.JPG

    M1410025.JPG

    M1410026.jpg

    M1410027.JPG

    M1410028.jpg

    M1410029.jpg

    Finally, cut a hole in the wheelpants for the axle and glue them on.

    M1410030.jpg

    M1410032.jpg

    Alright, almost there!

    Let's prepare the motor for mounting. First, another new tip for longevity: I have often found that after quite a few hard hits, it's not uncommon for motor wires to break. Often this happens just inside the motor and it means that motor is toast.

    You can prevent this by adding some Welder glue to the wires where they exit the motor. This fillet of glue will protect the wires and make them last longer.

    M1410018.jpg

    M1410020.JPG

    Next, you should install the prop adapter. If you are using GWS props (recommended on Lite aircraft) then you will find that the newer batch of GWS SF props do not have a hex near the hub, they are round. You will need to use a round adapter ring to fit them. The motor comes with two adapter rings, test fit each one to find the correct size and attach it with a tiny dab of Welder glue so it doesn't come off in a crash.

    M1410022.jpg

    Now mount the motor on the airplane with the supplied screws.

    M1410033.jpg

    Next, route your aileron servo wire through the fuselage and down to where you will mount the receiver.

    M1420001.jpg

    Mount your ESC with a dab of Welder glue...

    M1420005.jpg

    As well as your receiver. Tie the wires up to keep everything compact and tight.

    M1420003.jpg

    Finally, route the ESC battery wire up through the fuselage, since the battery is mounted on top of the horizontal fuselage on this plane.

    M1420004.jpg

    And one final trick: we have found that it's best to cut a slot for the batteries with these planes. They roll more axially and stay more true during pushes and pulls. However, since you will likely want to fool with CG a bit, you only have one shot to mount it in the right place. So, for the first few trimming flights, just hold the battery on with T-pins.

    M1420006.jpg

    You won't be able to fly really hard but it will be enough to let you figure out if you got your CG right or not. Once you are satisfied with the position, cut a slot and you are good to go!

    built.jpg
     
  2. dth7

    dth7 3DRCF Regional Ambassador

    Nice build Cody. Did finally split the fuse on th CY. Could have used the fuse blende trick! Will add now.
     
  3. hone

    hone 150cc

    1,429
    0
    38
    Thanks for putting this build log together! I got a green one headed my way(thank you!)and will be following this for my build.
     
  4. Does anyone buy a brand new crack yak? Want this now instead... lol.
     
  5. Tymac300

    Tymac300 30cc

    10
    0
    1
    Looks awesome Cody! Great job on the design and color scheme. Can't wait to see it fly!!
     
  6. cwojcik

    cwojcik 70cc twin V2

    299
    2
    16
  7. Manta

    Manta 70cc twin V2

    497
    0
    16
    Ga.
    Very nicely done. Awesome looking plane too!
    Got some time on the crack edge yesterday in some crazy wind.. good fun
     
  8. cwojcik

    cwojcik 70cc twin V2

    299
    2
    16
    Thanks guys!
     
  9. ghoffman

    ghoffman 70cc twin V2

    345
    81
    28
    Nice!
     
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