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Yellow F-15 ARF Assembly Thread

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Yellow F-15 ARF Assembly Thread

Old 10-21-2016, 01:37 PM
  #301  
70 ragtop
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There is a set screw on the bottom side on the spar receiver that you mounted to the main plywood former/spar. You need a hole in the lower skin so you can insert a Allen driver into the set screw, and tighten it when you put the wings on, thats it. Check your manual, look at pix for step 77. Shows aluminum spar receivers mounted on main plywood former. Set screws are on bottom side of receivers.
Just my 2 cents, but I would recommend you have one of your local builders, club member or hobby shop guys, who is familiar with this kind of plane, go thru it with you before to fly
Old 11-28-2016, 10:38 AM
  #302  
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ok im trying to balance at 7 1/4 in". all i have left to do is install the batteries to balance it. These are some possible locations for the turbine and radio batteries. Getting into the mid section under the tray in front of the turbine is basically impossible. So, i figured i could try to put the larger 3cell as far back as possible and use it to keep the radio batteries in forward of the mid tray above the front landing gear. Does this seem like an ok setup? I could maybe move the turbine battery even farther to the rear close to the rudder servo distance aft, but i was worried about possible heat buildup near the A123 batteries. I have not installed the tamjets smoke pump yet but it could also be used to influence balance if needed. Any suggestions are very appreciated. Time to maiden this bird!
Thanks
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Old 11-28-2016, 12:55 PM
  #303  
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I maidened mine last week. The plane flies excellent.......no bad habits. Just watch your speed during the landing approach. I did not use the speed brake. With the flaps and gear down, it loses speed in a hurry. I settled on the factory rec. throws except on the ailerons. The ail are very effective, I'm using about 3/4". You will need around 6% down elevator with full flaps. I think your CG at 7 1/4" is a little too far forward. Most people are balancing at 7 1/2- 7 3/4". Mine balances at 7 5/8".....I'm leaving it there. I would not put your turbine battery back there if you can keep from it. I made a shelf that fits between the turbine and cockpit (in the raised fuse section just ahead of the hatch). My turbine batt is mounted to the top, while the RX batts mount to the bottom of the shelf. My ECU is also mounted to the shelf. My UAT is below the shelf on the floor of the fuse. It's a tight fit, but it works. Hope this helps. Good luck with the maiden..........you're going to love the plane.
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Last edited by bushong572; 11-28-2016 at 01:12 PM.
Old 11-28-2016, 01:59 PM
  #304  
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Thats good to hear! Your F-15 looks great! Well... if I put my batteries in the middle, I am going to have a lot of work ahead of me. I mounted the fuel pump, filter, air trap, wheel brake valve, and airbrake valve to the middle shelf. But with that being said, there is probably enough room to get everything in there with a lot of work. It will still probably balance quite a bit nose heavy. Maybe I will have to make the output nozzles heavier... I wonder of anyone else ever has a problem getting this aircraft to not be too nose heavy. Well, at least my next aircraft (and every one from now on) is a ADJets Diamond and will have PLENTY of room to work inside. I might as well plan on dismantling everything and getting that tray out. I will probably try to find a rearward spot for the smoke pump. I just wonder exactly how much heat actually builds up in the back around the bifuricated pipe? I wonder if anyone else has ever put a battery rearward. If there was no other option, I could wrap it in ample heat shield fabric.
Old 11-28-2016, 03:10 PM
  #305  
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Put it at 7 3/4" thats the sweet spot, she will land at a crawl with that CG. It won't do anything crazy or in a hurry except bleed off speed. If you are idle thrust you better be asking yourself why...
Old 11-28-2016, 03:19 PM
  #306  
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Originally Posted by Dieselman1220
Put it at 7 3/4" thats the sweet spot, she will land at a crawl with that CG. It won't do anything crazy or in a hurry except bleed off speed. If you are idle thrust you better be asking yourself why...

Good advice.................This is my first turbine. I worked my way up thru the EDFs and recently built a Skymaster F-15 with a 120mm fan/12s combo. You really have to be prepared for the throttle lag with a turbine. I made the mistake of going all the way down to idle on the landing approach. I was going to come up short and barely got the throttle to come back in time to drag it in. Lesson learned!

Last edited by bushong572; 11-28-2016 at 03:21 PM.
Old 11-29-2016, 04:24 AM
  #307  
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Yes flying a turbine isnt too bad, but go arounds can be nightmarish. I started out on a CARF Rookie 2 and all I can say is "thank god for good wheel brakes"! OK I will go with 7 3/4. Shaun if you happen to be listening, do you have opinion about installing the turbine battery aft of the turbine? Thanks for the responses everyone. Its too bad Y/A isnt still around...
Old 11-29-2016, 06:23 AM
  #308  
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do you have opinion about installing the turbine battery aft of the turbine?
Mine is mounted up against the side of the fuse behind the bulkhead/former that has the removable section at the top under the hatch. I built a balsa box (open on one side) around it and painted the outside with heat shield.
Old 11-29-2016, 02:34 PM
  #309  
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Great to know... thanks! I will try to do that especially since im going to take the c of G a little farther back.
Old 11-29-2016, 05:57 PM
  #310  
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Hi,

I actually carried all of my batteries in the nose, and still managed to get my CG at 7-5/8. I had my two receiver packs on top and the ECU pack underneath the forward-most tray. Someone mentioned adding down-elevator trim for full flaps--while YMMV always applies, I found that the natural ballooning of the nose put it right at the optimum landing attitude. At that point, I just managed the descent with throttle. I feel like I got some of the slowest landings with a scale jet I'd ever seen that way. Good luck!
Old 11-29-2016, 08:12 PM
  #311  
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Wow that's amazing you had all your batteries in the nose Shaun! I wonder if I am measuring from the proper location? I measured 7 3/4" from the front of the leading curve of the wing root where it butts against the fuselage. So in other words, I removed the wing and measured on the inner flat surface of the wing itself so I was not measuring on the curvature of the wing and carried the line underneath the wing to place my balance points. I wonder why I'm so much more nose heavy in general. Maybe turbine choice and/or placement is a big factor. I better make sure the air trap is empty for the weigh in. Thanks for your input.
Old 11-29-2016, 08:24 PM
  #312  
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No! make sure your UAT is FULL!. The UAT should never ever be empty, so CG it with the UAT full.
As far the flaps go, Ive had 3 YA F15s, They do not require flap correction. If it balloons its because you are extending the flaps too fast.
slow it the efff down. IT WILL NOT stall. You will start to get an outrageous sink rate, but it will not drop a wing.
Old 11-29-2016, 09:44 PM
  #313  
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Ah yes good point the uat is always full... thanks for the correction!
Old 12-04-2016, 11:31 AM
  #314  
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Ok so I have determined I need 10.9 oz. at the very back tip where I have the weight taped on in order to balance at 7 3/4" with the displayed battery setup and the smoke pump back behind the air brake. That seems like a lot of extra weight! Has anyone else needed this kind of weight compensation? Any suggestions?
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Old 12-04-2016, 02:46 PM
  #315  
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All 3 of my batteries are in the fuse behind the cockpit right where you have that switch (if that's what it is) laying on top. I have not heard of any YA F-15 requiring that kind of added weight.I don't know anyone running a smoke system on one, though. I measured the CG with a straight line on the root from the leading edge (I think you said you did it the same way). I would probably shoot for 7 1/2" and add as little weight as you have to.
Old 12-04-2016, 05:25 PM
  #316  
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So sad this and the Yellow F-22 are no longer available.......
Old 12-05-2016, 05:27 AM
  #317  
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Well I realized I had some relatively "easy access" in front of the fuel tanks, so I put the receiver batteries in there. That moves them back a foot or so!
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Old 12-05-2016, 04:19 PM
  #318  
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Hi,

The good news is that the only ill-effect of the bird being nose-heavy is that you'll have a slightly higher landing speed and won't be able to do those nose-high (aerodynamic breaking) landings that 15's are so known for. Otherwise, it tolerates a very wide CG envelope very well. Even when slightly tail-heavy, they don't porpoise and snap. Another bit of good news is that she'll fly heavier than you'd imagine. Flip side of that is that the gear are not the stoutest on earth. The F-22 gear are very tough but these are relatively fragile in my opinion, so you'll want to land her as softly as possible. That means a shallow descent rate (as opposed to a 'carrier landing'). Like Dieselman says, she'll slow down if you let her.
Old 12-06-2016, 03:43 AM
  #319  
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That's good to hear Shaun thanks for chiming in. Well I just checked th cg with the batteries in front of the fuel tank and that brought the required weight to add to the tail to 5.1 oz. That's without the smoke pump too which I wasn't planning on installing until several flights in. I would still need to figure out the smoke tank situation as well. I'm Considering the details4scale drop tank for smoke but I also have this nice intairco tank that holds 16oz. The tank and mounting bracket weight 5oz. as seen in the pic. I wonder if I could manage to make it work and balance if I installed it in the position it is shown in the pic or if there would be too much heat...even if I shielded it with heat resistant fabric as seen in the pic?
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Old 12-06-2016, 04:09 AM
  #320  
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16oz of smoke fluid won't last long enough to be worth the trouble IMO. I had 24 oz in mine and it went quick! I now have 36oz.

Just a thought.
Old 12-06-2016, 08:14 AM
  #321  
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Hey secret agent... i have never had a smoke system so that is good to know. the drop tank from details is 50 oz. so that would be a better route.
Old 12-06-2016, 08:20 AM
  #322  
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Check out this thread, Jetpilot24 used a centerline tank on his Skymaster F-15 and ran his smoke injector tube down the pipe and outside the jet so it doesn't get smoke oil inside the pipe. I'm going to try the smoke injector pipe thing in mine.

http://www.rcuniverse.com/forum/rc-j...uys-thing.html
Old 12-06-2016, 10:15 AM
  #323  
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Dude awesome link thank you for that I'm going to do that but I will have to put 2 smoke injectors for twin smoke trails!
Old 12-06-2016, 11:51 AM
  #324  
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Actually, scale is only one smoke trail. Look up any google image of the blue angels F-18 and you will see that only their port engine has smoke.

If you want to keep it scale stick with one, but if you want two it wont hurt. It will go through smoke fluid much faster with two though.
Old 12-06-2016, 11:58 AM
  #325  
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Here's a good pic.
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