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Oct 17, 2007, 04:55 AM
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Correct Thrustline setting for F-22 using ruler/straightedge


NOTE: you MUST use a flexible interface (i.e., clear tape [roughen outer surface] over raw foam, coming around outboard side of rear of vertical stab for extra security in crash .... and 5-min epoxy, which stays moveable for at least an hour!), because these angular settings MUST be flight-tested and then "tweaked" by hand-twisting motor for best results!
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Oct 17, 2007, 05:08 AM
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Do NOT use template method ....


... because it is not likely to give good results! This method proved very difficult to use after weeks of testing in the factory. Actually, to do it this way, you need a hard JIG that holds the entire airplane (the fin may be assembled incorrectly, etc.) ... AND that jig must have its results repeatedly flight tested ....

SO, use ruler/straightedge method shown on previous post and do NOT follow this >>
Oct 17, 2007, 06:29 AM
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Motors MUST be parallel with fore-aft fuselage centerline!


And remember, the motors MUST be exactly PARALLEL when viewed from the top. If you need to add filler material or extra 5-min epoxy (or 5-min epoxy with balloon-filler, etc. ) to get the motormount parallel, then DO so! When the props are rotated to lie horizontal, parallel to the wing surface, when viewed from the top the left and right props must line up and lie on the same straight line.
Oct 17, 2007, 07:14 AM
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IMPORTANT detail


The CRITICAL motor thustline is actually TWO angles:

1. the thrustline angle when viewed from the side (see dwg in Post #226 above)

2. the thrustline angle (ZERO degrees!) when viewed from the top

BOTH of these angles must occur at the SAME TIME !

This requires several quick iterations, first checking from the side, THEN from the top, then from the side again, then from the top again .... until both side AND top angles are correct. Then you must flight test and re-adjust if necessary. And this is really all easier DONE than said (trust me: I have done it MANY times on many planes! We are talking about a minute or two total "tweaking" time!). Lee
Oct 17, 2007, 05:17 PM
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msim's Avatar
so, this would mean you would have to use a different motor case since the stock one is angled down.
Oct 17, 2007, 05:29 PM
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No, just make sure the motors and props are positioned at the angles indicated above. If that requires fillers or work on the motor housings, then do it. Actually though, this "down" angle as you refer to it should be just about right to properly position ... as that part was originally designed and made to join the vertical stabilizers at EXACTLY the correct angle to fit with those specified above. Just put it back where it was DESIGNED to be!
Oct 17, 2007, 11:45 PM
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Am I understanding this correctly? The position of the motor on the v-stab (i.e., distance from the top measuring down) isn't very important, it's getting the alightnment correct? So if I install the motors a roughly the middle of the v'stabs that'll be okay assuming I get the allighments?

Jay
Oct 18, 2007, 02:11 AM
Wow, Im starting to understand the factories reason for changing the design. If the angles are this criticle how would the factory ever hope to get them trimmed just right?
Oct 18, 2007, 05:57 AM
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The prop tips must be 1.5 - 2 mm (no more /no less) from the rear of the vertical stabilizers; i.e., from the rear corner where the vertical and horizizontal stabs meet, as in my drawing (can be a bit higher from the upper surface of the horizontal stabiliizer farther out: put clear tape over horiz stab there!); i.e., as close down and forward as you can comfortably get without hitting the plane as the prop flexes forward under load.

While the angles ARE critical, they are no more critical than any OTHER aspect of this plane. Shifting the LIPO 1 mm forward or removing the landing gear (which you should, if at all possible, flying over soft grass) have a pronounced effect on flying, for ex.

We made a jig to fix the motors on the tail, as well as one to make holes for the motor mount to key into on the vertical stabilizer. Every sample I tested that was made that way flew perfectly. The only problems came from another jig used to assemble the upper and lower body halves. When that was used incorrectly or if the foam pieces were somehow twisted in molding or handling, THEN they would not fly right. The factory, ITC and RS moved the motors because they thought it was funny to have the plane fly FAST without the user being able (by accident or inexperience) to slow it down and stall or come down. The people who made those decisions are extremely INEXPERIENCED with RC planes and just made a dumb decision, that's all. They were very naive and did not fully consider the consequences of a noseheavy plane that cannot turn tighly or be slowed down enough to land properly or even be flown in a confined space, which the UNmodded version definitely can (see videos and read posts by all those who have properly made this really easy UNmod!). This decision was NOT made because they had not solved the problem of accurately fixing the motors to the vertical stabilizers.

The information I gave is exact and correct and not THAT critical if you are reasonably careful. Anyway, it is easily "tweaked" and made PERFECT. Lee
Oct 18, 2007, 01:08 PM
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The UNmod DOES work, folks


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starscream mod! really works great! - 10/16/2007 8:32:57 PM

crazychris46dividedby2
Posts: 94
Joined: 5/13/2007
From: glens falls, NY, USA
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if you own the transformers star scream and havent yet done the mod which involves relocating the motors back to there original position on the vertical stabilizers then i highly recommend doing so. it does however require a little skill an patients to do but it is deffinatly worth the time. i was doubtful about doing this mod or "un-mod" at first but i must say its an EXCELLENT JET after doing so. after i did the final adjustments to get everything balanced out i went out for the first TRUE flight ive had with it. within 1 minute of flying it i pulled off a very successful loop, followed shortly by a nose up barrel roll. incredible, thanks lee for showing me what this jet was supposed to be like. later, chris

_____________________________

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IF YOU CANT BEAT IT..............................MOD IT.
Oct 18, 2007, 05:22 PM
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jas_Qfix's Avatar
"within 1 minute of flying it i pulled off a very successful loop, followed shortly by a nose up barrel roll. incredible, thanks lee for showing me what this jet was supposed to be like. later, chris"

Chris if you are reading this can you explain the control sequences to do loop and barrel roll?
Oct 19, 2007, 12:44 AM
Dang it, Ya,all finally convinced me to give one a try. Anywhere to get a better buy on one than R.S.?
Oct 30, 2007, 12:52 PM
I just did the mod. I am new at this. I have some adjustments to make. What I can't figure out is why the plane rocks back and forth under power but glides beautifully. What isn't right? Any thoughts?
Oct 30, 2007, 01:04 PM
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Without any further information, I would guess that it is just beginning to stall. You didn't mention at what power level this rocking occurs. It is most likely that the thrustline is pointing too far down, that is, it appears to intersect the bottom of the body, viewed from the side, too far back (NOT under the engine intakes, but behind that). In any case I advise rotating the thrustline a little bit more parallel to the body (front of the motors up a TINY bit more, rear of the motors a BIT more down).
Nov 11, 2007, 04:06 PM
Have fun
airpower's Avatar
sweet. looks awsome, soooo, where do i buy one????


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