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  1. #426

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    RE: Jetlegend Mig 29 Fulcrum

    I've just seen that Robbe will be releasing an hydraulic kit with different size cylinders.
    Hopefully more reliable than the UMS system but probaly more expensive as well, might worth a look anyway page 58-61 of the 2011 catalog.
    http://www.robbe.de/robbeextra/Katal...011English.pdf

  2. #427
    ianober's Avatar
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    RE: Jetlegend Mig 29 Fulcrum

    I like the stainless steel construction of the system but it creates problems. First of all I can only imagine the price of all those components, it is gonna be expensive. They could have saved some money and weight and just used aluminum. Second, it looks like there system adds a couple return lines to the tank and just looks more complex. Nice cylinders though.

    So far I have had no problems with the UMS system, it works, its inexpensive and its simple.

    Jim, I would be curious to see the insides of your cylinders after 20 or so flights. Please keep us posted.

  3. #428
    Jim Cattanach's Avatar
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    RE: Jetlegend Mig 29 Fulcrum

    Managed to fly the Mig yesterday. Very nose heavy. I had moved the CG back half an inch from the factory position. I kept adding lead to the tail & finally arrived at a position that suited me. It is at the rear of the front brace spar. I am now removing all the lead & repositioning the batteries to give this position.
    As a result of being very nose heavy, the first landings were a little fast. We test fly our jets on a large salt lake. On one of these landings, I was slowing down & the nose wheel hit one of the very few stones at this site. It knocked the nose gear slightly back from the locked position & it jammed. It took a little force to get it back in position. The end result was, with enough air pressure to lift the gear, the nose gear would not lift. It remained in the locked down position, unless I moved it forward till it clicked, it then went up. I think the effect is the same as everyone was having with wear on the shuttles after a few flights. I just hastened the process with my stone incident.
    I had a number of good flights with the nose gear locked down. One of the small mains gear doors fell off (I found it), the ones with the rubber band. I may not bother refitting it, if I cannot find a more secure way of stopping it blowing back, when the rubber band breaks.
    This morning, I stripped down the nose cylinder & sure enough, it has gone back to the shuttle system (see photo). I fiddled about with the shuttle, cleaned it up, made some adjustments & filled it with silicone grease. After fitting it back, it works perfectly. We shall see how long it lasts.

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    JET FLYING:- Resistance is futile. You will be assimilated.

  4. #429

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    RE: Jetlegend Mig 29 Fulcrum

    Jim,
    Congrats with your first flights. You will notice from my photo that I too am flying with the CG at the back of the top brace. It would be interesting to know of what material the internal shuttle is made of as the original ones got badly scored after a few flights.




    John
    CRASHING IS NOT AN OPTION.

  5. #430
    Jim Cattanach's Avatar
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    RE: Jetlegend Mig 29 Fulcrum


    ORIGINAL: johnls

    Jim,
    Congrats with your first flights. You will notice from my photo that I too am flying with the CG at the back of the top brace. It would be interesting to know of what material the internal shuttle is made of as the original ones got badly scored after a few flights.






    John
    Thanks John. The shuttle is still aluminium with steel balls. I unscrewed the steel pushrod from the shuttle. This gives access to an allan screw. There is another allan screw at the other end. I held one & unscrewed the other a couple of turns, then reassembled it all with plenty of silicone grease & it now works fine. A bit hit & miss, but as long as it works, I am happy.
    JET FLYING:- Resistance is futile. You will be assimilated.

  6. #431

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    RE: Jetlegend Mig 29 Fulcrum

    What I found was after about 16 flights the ball bearings had flattened out the aluminum end plates and began to wear grooves in the cylinder walls, making locking problematic. Best of luck with yours, It is something to keep an eye on. Although having said that, the issues I had were with the mains. The nose gear always worked fine.



    John
    CRASHING IS NOT AN OPTION.

  7. #432
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    RE: Jetlegend Mig 29 Fulcrum

    Well I was fiddling around with my sequencer the other night and found that 8 seconds is not enough time for the gear to come up and be stowed before the doors close. I need more like 10-12 seconds and 8 is the max for the RCBee so I am a little bummed. I think I am going to look at some other sequencers but ultimately I am thinking about just putting a button valve on the gear so the doors will open and close when the gear moves. I think this would be the simplest way to go.

  8. #433

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    RE: Jetlegend Mig 29 Fulcrum

    What Transmitter are you using? I have programmed my sequencing through my Futaba 14MZ at about 11 seconds. I do not use an on board sequencer.




    john
    CRASHING IS NOT AN OPTION.

  9. #434
    Jim Cattanach's Avatar
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    RE: Jetlegend Mig 29 Fulcrum

    Got a bit of a problem. When trimmed, my right elevon is one inch lower than the left for straight & level flight. The flaps & ailerons are set spot on. I have balanced it fore & aft.
    At a loss to explain this.
    Oh & my nose wheel, which I thought was working fine, is not. It collapses on landing & sometimes before take off[:@].
    JET FLYING:- Resistance is futile. You will be assimilated.

  10. #435

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    RE: Jetlegend Mig 29 Fulcrum

    Do I understand what you are saying. That to fly straight and level, with the ailerons at neutral, there is a difference in the left and right elevators (stabilisers) of one inch!! Measured where? that seems a massive amount, has this suddenly happened or has it been there from the first flight? Mine has required no trim what so ever.
    Sorry to hear about your nose leg collapsing I think the locking ball idea is flawed.



    John
    CRASHING IS NOT AN OPTION.

  11. #436
    F15driver's Avatar
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    RE: Jetlegend Mig 29 Fulcrum

    Ian,

    Included below is a video of the UMS system with the Jet Model Products sequencer. This unit uses DIP switches which allow up to 5 seconds delay before the doors close. I think this might be extended a little with an in line restrictor if needed on the gear up cycle. As you can see from my video, I don't think I'll need to delay the doors as the gear is in before the doors start closing.

    http://www.youtube.com/watch?v=Bn4STXqY8IM


    Bart, thanks for all your help on this project. I should be getting a Rhino as the power plant in about 2 weeks.

    Regards,
    Rob
    F15driver
    Don't look back, they may be gaining on you!

  12. #437
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    RE: Jetlegend Mig 29 Fulcrum

    Ian,

    If you want to try it, I have a Jettronic sequencer which will delay the gear doors closing for up to 13 seconds. I personally found this sequencer complicated to program accurately. I preferred the straight-forward flip the switches Tom Cook approach i.e. the KISS principle. Let me know.

    Rob
    F15driver
    Don't look back, they may be gaining on you!

  13. #438
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    RE: Jetlegend Mig 29 Fulcrum

    So far the Jettronic sequencer seems to be the only one I have found that has enough time possibly. 8 seconds just isn't enough. I am using a JR 12X for my radio so I don't think that I can program the delay in but I will research it. Rob, let me know what you want for the sequencer and I will let you know. I am thinking about which way I wanna go. The RCBee works great but the 8 seconds they claim feels like 5 or so, it doesn't feel like a true 8 seconds.

  14. #439
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    RE: Jetlegend Mig 29 Fulcrum

    Rob, what battery are you using for your system? My gear are not that fast, is there a way to adjust the speed?

  15. #440
    Jim Cattanach's Avatar
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    RE: Jetlegend Mig 29 Fulcrum

    ORIGINAL: johnls

    Do I understand what you are saying. That to fly straight and level, with the ailerons at neutral, there is a difference in the left and right elevators (stabilisers) of one inch!! Measured where? that seems a massive amount, has this suddenly happened or has it been there from the first flight? Mine has required no trim what so ever.
    Sorry to hear about your nose leg collapsing I think the locking ball idea is flawed.



    John
    It has been there from the first flight. On the maiden, I had to trim it a lot on aileron (elevon) for straight & level flight, wing ailerons at neutral & when I landed, the one inch was the trim adjustment on the elevons. The one inch difference is measured at the rearmost root of the elevon. Initially I thought the reason was, the lateral balance was off, so I adjusted that, but it made no change. I have lined up the ailerons & flaps directly in line with the wing tips. Everything about the fuz & wings look straight & symetrical. The jet flys ok with this setup, it just looks stupid.
    Re the nose gear, I will dismantle the cylinder again & see if I can do anything. Failing that, I will buy a new cylinder. It did work ok prior to the nose wheel hitting that stone. I will also fit a skid on the nose, before I grind a hole in it.
    JET FLYING:- Resistance is futile. You will be assimilated.

  16. #441
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    RE: Jetlegend Mig 29 Fulcrum

    Ian,

    I'm using an old A123 which is 6.6 volts. As far as I know, there is no way to program the speed of the system. I do have the UMS adjustment turned fairly far to the left but I think that just determines how long the pump runs, not the system speed. A freshly charged LiPo might speed it up a little.

    Sent you a PM.

    Regards,
    Rob
    Don't look back, they may be gaining on you!

  17. #442
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    RE: Jetlegend Mig 29 Fulcrum

    Jim,

    Do I understand you are mixing your elevators with the ailerons? Is this scale for the Mig?

    Regards,
    Rob
    Don't look back, they may be gaining on you!

  18. #443
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    RE: Jetlegend Mig 29 Fulcrum

    Hi guys, just me again.

    Ian
    You are right about the RC Bee, they claim 8 x 1 second adjustable increments but I timed them and they are only about half second. I ended up using an "AirPower" unit in my Mig which is fine (need about 5 seconds) except whatever time you set for gear up-door close you also have to have for door open-gear down, bit weird when you fly past and hit the gear down command and all you see is the doors open.....5 seconds is a real long time when you are wondering if you will have wheels!!

    Re gear speed, my thoughts are minimum 2 cell lipo but also you must have 4 mm tube everywhere you can, also as mentioned earlier check that your 5 way valve is moving all the way, if it does not then the spool will create a restiction, if all else fails check the barbed fittings on the 5 way valve, there may be something stuck in one of them or not drilled all the way through.

    Jim
    I initially set my wing to zero incidence and then set both elevators to zero with the wings as a reference, like John, I have hardly had to touch it since. You may get a bit more of a clue if you put the meters on it. As for the nose collapse, mine did the same thing when it was running on air and I did not hit a rock, Isimply put the brakes on hard, ground the front knuckle, under the fuse and the probe on the front now sports a flat spot under the tip.
    Bart

  19. #444
    Jim Cattanach's Avatar
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    RE: Jetlegend Mig 29 Fulcrum


    ORIGINAL: F15driver

    Jim,

    Do I understand you are mixing your elevators with the ailerons? Is this scale for the Mig?

    Regards,
    Rob
    Hi Rob. Yes, I am mixing the wing aileron to the aileron function of the elevator. I am glad I did, as with the tiny wing ailerons, I don't think I would have been able to counteract the roll problem I am having. However, as the wing ailerons are always neutral in level flight & do not alter with elevon trimming, I don't see how this setup would cause my problem. My friend Mario has a JL SU27 & uses the same coupling, with no such problems.
    JET FLYING:- Resistance is futile. You will be assimilated.

  20. #445

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    RE: Jetlegend Mig 29 Fulcrum

    I am baffled with your problem. For the first few flights I would keep elevators and ailerons separate. That way I could understand where the problems lie. As the elevator is more powerful than the aileron I would have thought with the setup as you have it that the elevators would be at neutral and the ailerons would be displaced to compensate. By separating the functions you would gain a better understanding of any problems. I reiterate, on my Mig (with separate elevators and ailerons) it fly's with all surfaces at neutral. (see my photo of the elevator neutral position post361).
    Regarding your nose leg. Remove it from the fuselage connect to a hand air pump. Pump this, and using your hand to slow the movement down, allow the rod to move to full travel. Can you hear a click? This is the ball bearings moving outwards and locking in the cylinder groove. Originally, on my air set up, this did not happen on one of my mains. The rod was traveling too far, allowing the ball bearings to go past the cylinder groove. This in turn meant that the leg was held only by the ball bearings jamming into the cylinder lining, creating wear and either jamming in position or refusing to stay down. I rectified this by placing a shim in the cylinder at the end to stop the piston at the correct point. If the ball bearings are in the cylinder groove, and HELD THERE BY AIR PRESSURE, then the leg can't move. (unless there is excessive wear which at this early stage is unlikely). Also make sure that you haven't put excessive amounts of grease around the ball bearings -use silicon lube only.



    John
    CRASHING IS NOT AN OPTION.

  21. #446
    Jim Cattanach's Avatar
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    RE: Jetlegend Mig 29 Fulcrum

    John. I am a bit reluctant to use only the tiny ailerons on their own. The reason being, if the problem still exists, then even at full throw, they would not be able to counter the amount of adverse roll & I would lose the model. I will reduce their throw to zero & try using only elevons, although I don't think that will make a difference, as the wing ailerons would be at neutral in straight & level flight anyway. I have had small variations in elevons before, but an inch is massive & must be countering a major cause that is not apparent.
    I am also completely baffled. I will work on the problem.
    I dismantled the nose cylinder again & made some more adjustments (you can alter the throw of the shuttle by turning two allan screws at each end). This affects the point at which the balls are pushed out the holes. The nose now locks again, but the system only works while there is air pressure.
    JET FLYING:- Resistance is futile. You will be assimilated.

  22. #447
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    RE: Jetlegend Mig 29 Fulcrum

    Jim,
    To have the amount of taileron offset to fly straight and level is very odd. I would start by getting a couple of incidence meters on the wings. Don't forget to check the tips as well as the roots.
    I picked mine up yesterday. Looks great.

  23. #448
    Edgar Perez's Avatar
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    RE: Jetlegend Mig 29 Fulcrum

    I made a drawing with the full conversion. Can anyone confirm its correct?
    Thanks
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    Edgar Perez
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  24. #449
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    RE: Jetlegend Mig 29 Fulcrum

    That looks about right to me Edgar.

  25. #450

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    RE: Jetlegend Mig 29 Fulcrum

    For those of us using the modified air set-up; JL have fitted some in line air restictors to the secondary cylinder, I guess to delay the action and harmonise better with the main cylinder. Anyone who recieves a new MIG will have these fitted though upgrades, like mine, will need to add them.
    I did have a problem with one secondary cylinder were the locking pin would not release. I dismantled it and gently filed the peaks on each side frame were the pin locates and locks. It works perfectly now after many ( and I mean many) test cycles.

    Cheers

    Jeff
    Exclusive UK JetLegend Dealer


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