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The Skymaster Northrop T-38 Talon Project of 2019

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The Skymaster Northrop T-38 Talon Project of 2019

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Old 03-03-2019, 04:19 AM
  #151  
aehaas
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Originally Posted by sysiek View Post
please check your elevators if they not opposed the airfoils should be inverted the flatter side up and the rounded down this jet as the f-4 have inverted airfoil ,I will lower the expotential to 10-15 and lower the throws too much expotential could make the jet actually more jumpy on the end of stab movement ,hav the problem before on my f-22 and now it’s perfect,

FYI, yes the airfoil is as you say it should be. It is the only way you can install the elevators. I thought it was odd but having seen you show this and it being the only way they fit into place I went with that arrangement.

I have 3 levels of throw for my surfaces. I always maiden with the middle settings so I can give it more or less as needed. The ailerons are about right in the middle setting but the elevator was too much. I took the lower setting and moved it to my middle position for the next flight and took off some expo. It was 20 and now 15. I have 0 expo when pushing the elevator. For some reason I fly best inverted with no expo and in some cases negative expo when pushing the elevators.

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Old 03-03-2019, 05:08 AM
  #152  
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I was reviewing the video. You can always pick up some things when doing so. For one I noticed the air sock was showing a 15 MPH cross wind when I was coming in for the landing. After I touched down I needed to give it full right rudder to stay on the pavement:


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Old 03-03-2019, 06:12 AM
  #153  
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Oh the dreaded flap slap failure. Immediate pitch up to a stall at pattern altitude. Handgrips -raise, triggers - squeeze
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Old 03-03-2019, 01:43 PM
  #154  
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Nice one Ali , good maiden , plane still in one piece - was a good day
Yes as you say Ali - still some minor trimming to be sorted , seemed to be a touch pitch sensitive
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Old 03-06-2019, 08:55 AM
  #155  
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Default Scoops

I got the correct paint and sprayed up the scoops. They are now mounted to the plane:






I am planning on a second flight tomorrow.

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Old 03-07-2019, 11:08 AM
  #156  
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'Back from the second flight. Much more subdued today. 'Sorry, nobody there to take a video. I am getting close on trim and throws. No bouncing around. I tried a knife edge and was holding at 120 MPH but had some coupling, will work that out at another time. The plane tends to slow down more than other jets while into turns I noticed. I generally give more throttle in every turn when I fly jets. Especially if I was only doing "average" speeds on straight-aways.

I tried the gyro again and did not have any oscillations on the high setting but was not going top speed either. For now the Spectrum AR3000 gyro is set at around 25% for normal flight and 40% when the gear is down and the flaps are set to landing position. All flight surfaces have the same percentage settings.

Next is to do some loops and cubans.

I had 1.3L of fuel left after a 5 1/2 minute flight. I upped the timer to 6 minutes to see where I end up next.

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Old 03-08-2019, 04:19 AM
  #157  
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Good to hear the successful flight reports

David
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Old 03-08-2019, 06:25 AM
  #158  
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I ended up installing rubber band on the tiny nose door and it comes up with the gear
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Old 03-08-2019, 10:03 AM
  #159  
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I ended up using a servo that was 50% stronger for the small nose door and made sure I had 100% mechanical advantage with the door fully open. It worked fine on the second flight yesterday.

There was a mishap however. After I landed and shut it down there was a gust of wind that blew the horizontals stabs down hard. One got stuck vertically somehow. I could not easily straighten it so I turned the receiver on. There was a grinding noise and still the stab would not move. I had to open it up and free it but the servo was stripped. I do have an extra servo. I am into the repair now. I am planning on adding some blocks to prevent over rotation of the stabilizers from this point further. Take Note - this is a must.

Smart people learn from their mistakes (most of them anyway).
Really smart people learn from the mistakes of Others!

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Old 03-09-2019, 12:05 PM
  #160  
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I installed the rubber baby buggy bumpers on the down elevator side. I used sticky rubber feet on square balsa posts. But I also glued them in place around the edges. When the epoxy dries enough I will do the bumpers on the other side. The overall motion is still more than twice the "high rates" setting. When the servos are energized obviously there is no need for these motion limiters.

When there is no power to the servos however the elevators can passively move past 90 degrees and get stuck. This happened with just a gust of wind the other day. Also, when stuck down the elevators almost touch the ground making it hard to wheel the plane back to the benches.





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Old 03-09-2019, 03:46 PM
  #161  
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Hi I will install the push rod on the first servo arm hole from the center not the second or third this will make the jet less jumpy and almost no expotential needed this will make the jet a lot more less jumpy and comfortable to fly,at least this works for me, or drill one between and try on the medium and see if you like this way.
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Old 03-11-2019, 06:19 AM
  #162  
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Old 03-15-2019, 10:51 AM
  #163  
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OK, I think after three flights it is about dialed in. The only thing that is lacking is enough braking power. The ones supplied are discs with a sand-paper like surface. I need to see if these can be optimized or maybe I need something else. Another option is to use more pressure but then I need to have an air tank and I am trying to avoid anything that extends the set-up time and aircraft weight.

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Old 03-16-2019, 12:06 PM
  #164  
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Curiosity - what are your final trim settings ?
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Old 03-17-2019, 04:12 PM
  #165  
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Originally Posted by scoeroo View Post
Curiosity - what are your final trim settings ?
'Been thinking of how to answer this. It depends on a lot of things per aircraft. I can say that the elevator is giving me a little up elevator at level flight with flaps up. It is not directly even/level/in line to the wing angle. This goes along with the fact that the plane is a bit nose heavy fully fueled. There is probably less up elevator as I was able to move some of the weight of the fuel back over the CG whereas this model normally has all the fuel forwards of the CG.

The elevators are positioned with a little bit of down elevator with take-off flaps. And a little more down elevator with full landing flaps at 45 degrees down. It is just a few mm difference, not as much as the plans would suggest.

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Old 04-15-2019, 05:29 AM
  #166  
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I am out of the loop for a few weeks more but I will get back to the plane soon. In the meantime there are some developments on the JetCat P-130 turbine. I did not mention previously that it seemed to have more power than advertised and it sucked up more fuel than advertised. This may all be true as one reads this thread:

JetCat P-130RX

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Old 06-19-2019, 07:09 PM
  #167  
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So after some break and finishing up the big f-18 I got back to the f-5 so today just did some bondo to the leading edges right by the fuselage they just dont match up with the wings as they should the wing stocked up in one place about 3/32 so the bondo its a only solution.



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Old 06-20-2019, 10:57 AM
  #168  
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Nice work on your plane. Its amazing how much work these planes are especially if you want to do a little customization.

For my T-38 I wanted to make braking stronger and long lasting. I changed to pneumatic Intairco wheels and brake hubs from Dreamworks. I had to add an air tank. It is a medium sized one as it only works the brakes. So far I filled it once, played with it in the shop, flew once and it is still essentially full of air. Also it has sat around for over a month. Obviously it uses about no air and there are no leaks. I had to use a U-aluminum channel inside the hub as the Skymaster struts are narrower than the Intairco slot on the hub. So a little fitting was needed. No big deal but the braking is now what it is supposed to be. This plane does come in, land, a little fast so it is important to have good braking as my field is only 500 feet long. If you are short at all or even long you will have your gear ripped out, its very unforgiving.

I have been busy with a lot of other things so further progress and test flying will be a little scarce for the time being.




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Old 11-07-2019, 03:48 PM
  #169  
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I got around to flying recently and took out the NASA T-38. I performed some loops, split-s and cubans. No issues. The only thing to keep in mind is that the model slows more than other jets while in turns so give it more throttle while turning. I got too slow once and almost got into trouble. It does take some getting used to. This is not a beginners airplane.

The JetCat P-130 is an excellent match, plenty of power in my plane.

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Old 11-07-2019, 09:09 PM
  #170  
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I think that Im going back to work on the f-5 this winter,Im still looking for retracts mechanisms to work with this model,the good news is that I have the struts with tires and most hardware including the pipe so the rest should be easy to find,check the cg maybe you could move it back 1/8 back by 1/8 usually if the model slows down on turns it could be slightly nose heavy ,the elevators creating vortex behind the jet and this could hold up the jet because of the back pressure behind,but maybe this is the jet flat bottom?
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