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Jetlegend Mig 29 Fulcrum

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Old 01-30-2011, 03:10 AM
  #376
Jim Cattanach
 
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Default RE: Jetlegend Mig 29 Fulcrum


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ORIGINAL: johnls

The cross bar looks different. It would help if JL adopted a bit of communication wouldn't it? I'm off to fly mine now, I'll see if I can get someone to video it.




John
Anyone know what this crossbar is? It doesn't seem to do anything. Perhaps it's some additional scale detail???
Just spent a whole morning fitting the first elevator servo & linkage. Used up most of my vocabulary of swear words in the process. However having done one, the other should be quicker.
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Old 01-30-2011, 04:05 AM
  #377
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Default RE: Jetlegend Mig 29 Fulcrum

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ORIGINAL: Jim Cattanach

Hi Rob. I tried to disconnect the nose gear cylinder from the oleo, but failed. It is a very tight fit & without resorting to a hammer & punch, I doubt if I could remove it. I don't want to use force to dismantle it, as it all works fine & I don't want to cause problems. I have taken some photos, as my oleo looks different from the one Shane posted. Mine has steering dampers & a crossbar with pins in the ends? It looks like a steering bar, but it's not. The locking mechanism must be inside the air cylinder. It is a solid lock, & clicks when it's in place.

The crossbar is only a scale piece.

when did you get yours with this nose LG ?
And do you have the newer mains ?
perhaps there was another change in the set and now thye come with the new mains and old internal lock nose gear ? my nose gear has the cross bar but no internal lock (or any lock for that matter).
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Old 01-30-2011, 04:15 AM
  #378
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Default RE: Jetlegend Mig 29 Fulcrum

Jim,

My strut looks exactly like yours. I don't understand why yours would click into a lock position when mine doesn't have any innards to cause such an event?

Jeff, do you have any comments here?

Regards,
Rob
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Old 01-30-2011, 05:39 AM
  #379
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Default RE: Jetlegend Mig 29 Fulcrum

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ORIGINAL: i3dm

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ORIGINAL: Jim Cattanach

Hi Rob. I tried to disconnect the nose gear cylinder from the oleo, but failed. It is a very tight fit & without resorting to a hammer & punch, I doubt if I could remove it. I don't want to use force to dismantle it, as it all works fine & I don't want to cause problems. I have taken some photos, as my oleo looks different from the one Shane posted. Mine has steering dampers & a crossbar with pins in the ends? It looks like a steering bar, but it's not. The locking mechanism must be inside the air cylinder. It is a solid lock, & clicks when it's in place.

The crossbar is only a scale piece.

when did you get yours with this nose LG ?
And do you have the newer mains ?
perhaps there was another change in the set and now thye come with the new mains and old internal lock nose gear ? my nose gear has the cross bar but no internal lock (or any lock for that matter).
I received my jet & gear on Friday. It left Jet Legend last Monday. They may have gone back to the original nose gear, although I have never seen any other types than mine.
The mains look like yours, with the additional cylinder pointing into the fuz.
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Old 01-30-2011, 05:56 AM
  #380
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Default RE: Jetlegend Mig 29 Fulcrum


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ORIGINAL: Jim Cattanach
I received my jet & gear on Friday. It left Jet Legend last Monday. They may have gone back to the original nose gear, although I have never seen any other types than mine.
The mains look like yours, with the additional cylinder pointing into the fuz.
Definitely looks like it ! please check the inner components of the nose gear cylinder and post some pics.
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Old 01-30-2011, 06:22 AM
  #381
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Default RE: Jetlegend Mig 29 Fulcrum

See post 373. Had another look at it & there must be some kind of locking mechanism inside the cylinder. Tried again to remove the cylinder to oleo pin, but it is too tight.
I am sure Jeff will be able to update us.
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Old 01-31-2011, 01:41 AM
  #382
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Default RE: Jetlegend Mig 29 Fulcrum

Saturday night I loaded the Mig in my van, for it's trip to Wroughton on Sunday. For the trip I needed the landing gear up as I fit the model on a shelf and had another model (Fei Bao T33) sitting on the van floor. As I got towards Wroughton I noticed the Mig landing gear was beginning to lower by itself, not a good start to the day. I resigned myself to having a bad day and to fly around with the gear down again, and I must admit I wouldn't have been too upset if it had crashed. After cycling the gear a couple of times( I am sure I still have an issue with oil bypassing a piston in just one of the main landing gears), I decided to give it a go. After takeoff I moderated the throttle to keep the speed down and to my amazement the gear behaved itself and retracted. After about 8 minutes I lowered the gear, again without a problem and landed the model. I then flew the T33 ( wow, what a fantastic plane!! but thats another story), and gave the Mig another flight. again everything worked fine. So all in all a good day, and it works. I'm going to get another piston made up for the offending landing gear (perhaps I'll put three O rings on it), and try again. A few more observations, My Mig has now had 22 flights on it and there is a lot of wear in one of the main landing gear, vertical tubes. This makes one of the main gear wheels flutter back and forwards due to the slop which looks naff. Also after every other landing the nose gear has turned so that it does not return to central. It needs to be re-centralised by adjusting a small grub screw at the back of the nose leg. The tension on this seems critical. Too much and the gear will not retract and too little and the nose wheel slops about. Has anybody worked out how this works?
As for a video, I gave a camera to Geoff White. It is now evident that although Geoff may be one of the UK's finest Jet flyers he is rubbish with a camera and at the moment I am having problems uploading to Youtube. Dick Spreadbury was there taking still shots so hopefully he will upload some later.


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Old 01-31-2011, 02:57 AM
  #383
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Default RE: Jetlegend Mig 29 Fulcrum

Morning John,

Yep, I am rubbish with a camera. I omitted to mention that Why do you think Dick never gives me his camera to take a few photos!

Geoff.

P.S. Great to see you finally getting your two models to behaves themselves.
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Old 01-31-2011, 03:13 AM
  #384
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Default RE: Jetlegend Mig 29 Fulcrum

John,

Good deal on your 2 successful flights on the Mig. Glad to hear it for those of us trying to get the gear working properly. I too have noticed that the tension on the small screw on the nose strut is critical to maintain a straight strut while at the same time allow the wheel to tuck back. Maybe someone can propose a fix on a rather dumb design. Bart, are you having any issues with this? Do you have a fix?

Looking forward to the video.

With good luck I should be in position today to see if my gear works when installed in the airplane. It worked fine on the test stand but you know how that goes. Put it in the airplane and the gremlins find the weakness!

Rob
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Old 01-31-2011, 03:24 AM
  #385
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Default RE: Jetlegend Mig 29 Fulcrum

On my Mig, the nose oleo has steering dampers fitted. This addition helps keep the nose wheel centralised (see photos on post 373). Perhaps, as mine has a locking nose wheel, Jet Legend may supply an upgraded unit with these two improvements?
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Old 01-31-2011, 03:26 AM
  #386
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Default RE: Jetlegend Mig 29 Fulcrum


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ORIGINAL: Jim Cattanach

On my Mig, the nose oleo has steering dampers fitted. This addition helps keep the nose wheel centralised (see photos on post 373). Perhaps, as mine has a locking nose wheel, Jet Legend may supply an upgraded unit with these two improvements?
Mine has the steering dampners but no locks.
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Old 01-31-2011, 03:30 AM
  #387
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Default RE: Jetlegend Mig 29 Fulcrum

Mine has got the two small steering dampers.(actually one fell off along time ago). I think they are more cosmetic than functional. The tension on the grub screw is the crux of the matter. I always fly off tarmac, It will be interesting to hear Shane's comments as he is a grass flyer mostly.
I've got the video to upload on Youtube, (don't hold your breath, there's a lot of blue sky!!)
http://www.youtube.com/profile?user=...s#grid/uploads


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Old 01-31-2011, 03:42 AM
  #388
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Default RE: Jetlegend Mig 29 Fulcrum

Hello Geoff,

Give Dick a kick and tell him to upload those photos he took.





John
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Old 01-31-2011, 12:06 PM
  #389
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Default RE: Jetlegend Mig 29 Fulcrum


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ORIGINAL: F15driver

John,

Good deal on your 2 successful flights on the Mig. Glad to hear it for those of us trying to get the gear working properly. I too have noticed that the tension on the small screw on the nose strut is critical to maintain a straight strut while at the same time allow the wheel to tuck back. Maybe someone can propose a fix on a rather dumb design. Bart, are you having any issues with this? Do you have a fix?

Looking forward to the video.

With good luck I should be in position today to see if my gear works when installed in the airplane. It worked fine on the test stand but you know how that goes. Put it in the airplane and the gremlins find the weakness!

Rob
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Hey guys
John, glad to hear that you at least got a couple of flights in with the gear working. Not sure of why your gear dropped on transport, but they are only being held up against the seals (as you noted) as oppossed to held down with the aid of the check valve, this being the case, the other seals that could give you some small grief are the ones on the spool of the valve.

As for steering, I found early in the peace that it is the thin nut on the end of the strut that you use to hold centre, I think the grub screw holds the oleo guts. This is what I suggested a while ago to you John but I am not sure you picked up on it -
In regard to your nose leg steering problems, I reckon I know what that might be as well. On the bottom of the strut were the suspension rod protrudes there is a large thin nut that locks the wheel assembly to the steering assembly (“mig steering nut” attachment), this nut needs to be tightened once you have re-centred the steering assembly to the wheels (loosen nut first). After I did that mine has been rock solid and most of my flights are from grass.
Did you find this helped originally?? I have not touched mine since.
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Old 01-31-2011, 12:11 PM
  #390
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Default RE: Jetlegend Mig 29 Fulcrum

Hi John

Good to see the Mig behaving, weather turned out much better than I expected so a bit dissapointed I made other plans and could not make it, was away in London.

Geoff - I should stick to the pit lane commentry, rather than flying shots,

P.S T33 looks nice
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Old 01-31-2011, 12:49 PM
  #391
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Default RE: Jetlegend Mig 29 Fulcrum

It looks like Yang has gone back to the shuttle system on the nose only. I've ran one of the cylinders on the bench and it seems to be fine after LOTS of cycles without showing any wear so I'm re-installing it in mine.

John,
I sent you some replacement cylinders - did they not arrive?

Jeff
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Old 01-31-2011, 01:10 PM
  #392
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Default RE: Jetlegend Mig 29 Fulcrum

Hi Jeff,
Yes, I,m running the cylinders that you sent, thanks. I could do with another solid piston, have any arrived?

Shane,
The point you made about the steering nut must have gone straight by me, I didn't know that. I'll take a look tomorrow.

Lewis,
You missed a good day. Don't listen to the weather man. I don't know who is worse with the camera, Geoff or yourself!!




John

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Old 01-31-2011, 01:13 PM
  #393
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Default RE: Jetlegend Mig 29 Fulcrum

Finally got my 4mm tubing and connectors today so I am hoping to have everything installed and functional tonight or tomorrow night at the latest. I will definitely post a video.
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Old 01-31-2011, 01:21 PM
  #394
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Default RE: Jetlegend Mig 29 Fulcrum

Mmm don't rub it in, lol
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Old 02-01-2011, 12:01 PM
  #395
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Default RE: Jetlegend Mig 29 Fulcrum

John,

my upgrade set came with a solid piston on the nose so you can have that.

I expected the the replacement sets to come with my last delivery but they didn't...

I suppose they'll come with my next batch...
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Old 02-01-2011, 12:50 PM
  #396
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Default RE: Jetlegend Mig 29 Fulcrum

Thanks Jeff, that should do the trick.

Shane, you where correct, it is the large thin nut on the bottom of the nose leg that determines the centre point.
I also found out why the main gear was oscillating. It is held central by the cantilever mechanism, of which mine has a bit of play, but also the locating pin had lost its circlip and was working loose.


John
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Old 02-01-2011, 05:14 PM
  #397
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Default RE: Jetlegend Mig 29 Fulcrum

Jeff,

ANy chance you could replace my solid nose cylinder with the self locking one ? i might still be able to use pneumatics in such a case.
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Old 02-02-2011, 10:55 AM
  #398
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Default RE: Jetlegend Mig 29 Fulcrum

Bart,

I want to thank you for all of your posts regarding the Mig 29. Everyone of them has been helpful, most recently how to tighten the nose steering to avoid wandering.

Now, the big question. I've completed the hydraulic installation and have two remaining issues. The first has to do with the Jettronic sequencer which I just need to play with the timing delays and I believe it will work. Right now it is only allowing either up or down, but not both. If I bypass the sequencer the system works so it must be the timing of the delays. The hard second question is : How do I get all the air bubbles out of the numerous lines? In one of your earlier posts, you suggested putting the Mig on its tail and sequencing it a few times. Is that still good or do you have other tricks to rid the lines of those pesky bubbles?

Like John mentioned in one of his recent posts, the cold weather is interfering with testing the system. Here in southern Texas it is now 21 degrees Fahrenheit, making the sewing machine oil a little thick in my unheated and uninsulated garage.

As always, John, I look forward to your informative posts.

Rob
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Old 02-02-2011, 12:19 PM
  #399
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Default RE: Jetlegend Mig 29 Fulcrum

Hi Rob,
First of all you are destroying our illusion of Texas being permanently hot and parched!
Secondly a tip to help set up the Jetronic sequencers. I set up the sequencer using servos in place of the valves. I fix a piece of masking tape to the servo, mark one for gear and one for doors, and then respectively, up and down, open and closed, at each end of the servo case.
The servo arm simply signals which direction each part of the system is driving in, in which order and at what delay. Play around until you are happy with no danger of breaking off gear doors.
I hope this helps.
John
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Old 02-02-2011, 07:26 PM
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Default RE: Jetlegend Mig 29 Fulcrum


Quote:
ORIGINAL: F15driver

Bart,

I want to thank you for all of your posts regarding the Mig 29. Everyone of them has been helpful, most recently how to tighten the nose steering to avoid wandering.

Now, the big question. I've completed the hydraulic installation and have two remaining issues. The first has to do with the Jettronic sequencer which I just need to play with the timing delays and I believe it will work. Right now it is only allowing either up or down, but not both. If I bypass the sequencer the system works so it must be the timing of the delays. The hard second question is : How do I get all the air bubbles out of the numerous lines? In one of your earlier posts, you suggested putting the Mig on its tail and sequencing it a few times. Is that still good or do you have other tricks to rid the lines of those pesky bubbles?

Like John mentioned in one of his recent posts, the cold weather is interfering with testing the system. Here in southern Texas it is now 21 degrees Fahrenheit, making the sewing machine oil a little thick in my unheated and uninsulated garage.

As always, John, I look forward to your informative posts.

Rob
F15driver
Hey guys

At work at the moment so I don't have my mig handy for measurments but the following will be a good guide.

Each cylinder will displace about 10 cc (0.6 cu.in) each time it strokes one way or the other. 1 metre of 4 mm OD tube holds about 7 cc of oil. So for each stroke of the cylinder you can "flush" the entire line, even if it is the nose leg. Once you flush the oil and air back to the reservoir, the bubble will make their way to the oil surface, whilst you are pulling oil from below the surface because of the clunk.

This all sounds simple except for a couple of gremlins which you need to be aware of. Air bubbles will always float to the top of the oil and disipate, however the thicker the oil and/or the smaller the bubble the slower they will rise. This is not only true for the resevoir but also the cylinders. If your fittings on the cylinders are facing down, then the air will be at the top of the cylinder and will be the LAST thing to be pushed out and therefore will not make it back to the rerservoir but instead will be trapped in the line only to be pushed back into the cylinder when you go the other way. So the answer for me was to orientate the airframe to try and put the cylinder nipple at the highest point before cycling the cylinder, this should try and put any bubble at the front of the oil stream heading for the reservoir.

However when doing this you also need to make sure that the clunk in the reservoir stays below the oil otherwise you just pump air back in and you have to start again.

Now this process should not cause too much greif because all the lines are relaitively short and the cylinders are so big so the air should only take one or two shots to get it out. The only other thing to watch out for is creating too much negative pressure in the reservoir. This can happen because the reservoir is a fully sealed unit (can't breathe) and if it has too much negative pressure you may be pulling air through the suction fittings between the reservoir and pump (or you may not have the tube pushed into the fitting properley). Once you have all the cylinders extended, loosen off the reservoir cap (plane will need to be nose up to stop the oil coming out) and let the reservoir equalize the pressure, do the cap up again and see how you go. I run clear tube between the reservoir suction and the pump so I can see that I am not pulling any bubbles through which would indicate this fault.

Last thing and I know it sounds dumb, but check that your pump suction line is connected to the right fitting on the reservoir and is pulling oil through the clunk line and that the clunk hose is not split, I think we have all hooked up the wrong lines on our fuel tanks at least once.!!!!!
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