Special addition Lumber Jack, "The Clear Cut," addition! - RC Groups
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Sep 29, 2007, 10:44 AM
The Predator
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Special addition Lumber Jack, "The Clear Cut," addition!

I won a big'ol 72" LJ at the Glacire Ridge combat event but, after building a few MONSTER size ships I just wanted something small fast and IN MY FACE FUN to fly. I traded with the Canuch for a 48" and some other goodies of his.
I had a really FUN time building this ship and just wanted to share a few build points I learned of along the way.
1) Gooping the WHOLE raw core full the night I got it was a smart move. That saved me LOTS of time since ended up doing three HEAVY coats of thinned goop and let it all soak in and dry before really getting the build going. The remaining coats were all IN FRONT of the CG line and on the WHOLE tip area!
2) I love the battery setup and man did I shoot in a ton more straight goop into the battery and balancing weight holes along with that gear. More drying. . .
3) The one SCARY part was siting the TE after the goop was dry to find rather disturbingly big bows in my TE due to goop shrinkage. I simply sanded down the drag spar with a long STRAIGHT piece of wood wrapped in sand paper, all better!
4) installing the spars was easy, I used pins stuck through the foam to hold my ribbons in place while I marked their location, (this works really GREAT). It not only holds the ribbons in place on, EITHER SIDE OF THE WING, perfectly stacked. It also allows the carbon to bend smoothly and naturally to reduce foam deformation from unnatural/tigh bends in the CF.
5) I put in deep servo wells and then simply shimmed them with coro and or foam to get PERFECT altitudes for the servo arms to just stick out. Then I just caulk goop in the servos along the top edge like on the Bees. I hope this works well, I think it will. I would have gone with internal rods but, I had a spar RIGHT next to my servo on BOTH sides.
6) Here's a cool move, I gooped the tail boom straight to the body of this ship and did not bother with the draggy coro mount. I DID however place a decorative piece of packing tape underneath where I glued on the boom. Now, if the boom ever breaks I can just peel off the packing tape (with the boom stuck to it) and BINGO, nice, clean and new, all set for a new tail EASY!
7) More innovation, I now thin goop one end of my pushrods to the clevis where the rod is NOT threaded vs soldering them on. This move is WAY faster and has a NICE benefit. Normally HUGE CRASHS end up trashing the elevons where they connect to the control horns, not this way. They have a tiny bit of elasticity for shock loads but, they will break away under BIGGER loads, servo saver AND elevon saver in one easy move! Plus, you'll never drip MOLTEN solder onto your brand new wing AGAIN!
8) Last, I thin gooped under and over the covering to make it SUPER tough.

I've ALWAYS loved the LJs and all the more if I can support my buddy the Canuck by making a few AWESOME ONES to show off some of their performance! This is an easy build for what you get, like a Bat. Very cool how it comes with a MONSTER battery right in the kit too!
You guys like the Predator modified tail for improved orientation??? AND COOLNESS?????
If I can just keep from dorking this guy early on I think I'll be cranking INSAIN DS acro with it. Perfct size and weigh for me and my crazy exploits!!!
P.S. My CG landed 1/8" behind the most aft CG recomended, PERFECT! and you wondered why I left the aft coro boom mount off? Wasn't the first time actually!
Time to RIP!
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Sep 29, 2007, 04:32 PM
ajroahkni's Avatar
Karl, wonderful work & innovation as always - could I get a closer look of your vert mount process?
Sep 30, 2007, 11:13 AM
The Predator
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I just lightly tack gooped down the CF boom THEN straightened it with a thumb tack and loaded it up with goop to lock it there (I gooped around the fin where it is keyed onto the body as well) and also more goop to protect the CF from the ground/rocks!
I maidened it yesterday with a hitec 555 I just got back from the repair facility. I foolishly thought that meant it worked!!! I hucked it into 30+wind and it was trimmed within 2 clicks of perfect out of my hand. As it got 100 ft away the wind picked up and went CRAZY, forced down a Thorn at that moment. The LJ was screaming fast instantly, somehow crossed an invisible roto shear for mega power, I think, it was getting tossed around HARD too and I felt spotty control, I thought, not sure due to huge turbulence if it was just air or air and Rx. It sure flipped over fast!
I FREAKED a second later as I lost control while going at the hill like a CANNON BALL right out of the barrel with my FRESHIE!!! The radio linked up again as it got close and I went into cardiac arrest! I had partial control got it into the wind and gently rested it on the ridge 2 feet from a 100 foot cliff, OMG. It was unscratched. I tested the radio to find I had glitches 25 feet away with the anntena down. I changed out Rx's and it flew GREAT even in rougher air! DSed it tenatively for a few minutes then put it away. The rodeo bowl/death troth is just to skecho for a BRAND NEW SHIP; it goes insain (BIG ROUGH DOWN) there with NO NOTICE a few times an hour! I'll be going to Jones Pass today!!!!
Sep 30, 2007, 12:47 PM
Registered User
Chief High Horse's Avatar
Thanks Karl,

Now I am going to do radio range checks BEFORE I cover these next two wings.

That LJ looks very nice.
Sep 30, 2007, 03:24 PM
Registered User
Hi Karl

Have you ever thought of putting a ballast tube in a LJ, particularly the 60V2 which I'm just about to start building? Opinions seem divided. I guess I'm thinking front side up to 40mph.

Oct 01, 2007, 11:05 AM
The Predator
The Predator's Avatar
It'd work well and I'll bet it would be worth it for you, not me. Having a nice grassy LZ, in my opinion, is where you can benefit from a ballast bay with minimal PAIN. On the rocky slopes I fly, I still want the weight but, I add the weight as goop armour since I'll REALLY be needing it for the ship to last any length of time. You may not need that armour and then the ballast bay would leave you with a MORE versitile ship. Leaves me with a toasted ship kabobed on the rocks!
I did get a new foamie personal best speed with my new little LJ 48" at 126MPH. My old best was 125MPH with a 60" JW. Relatively speaking, I was going ALOT faster with the little guy! I was pretty caerful to and it can home without a scratch!
Oct 02, 2007, 02:54 PM
Registered User
Some useful thoughts there Karl. I think I need to build two. One highly gooped up for now whilst I'm still learning and for when I'm on the rocky arenas and then try a ballasted version for when I'm more experienced and have a strong wind and a softer LZ.

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