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Jetlegend Mig 29 Fulcrum

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Old 08-22-2010, 04:14 PM
  #51
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Default RE: Jetlegend Mig 29 Fulcrum

Bart,

I read with interest your issues with the landing gear retracts. My Mig 29 should be delivered in a few days and I was hoping that your comments inspired JL to modify its mechanism to a stronger metal. Have you heard of any updates to their retract? Did you pass on your repair to JL?

Look forward to your comments.

Rob
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Old 08-23-2010, 03:38 AM
  #52
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Default RE: Jetlegend Mig 29 Fulcrum

Rob

I sent all the info plus more to Yang at JL via the distributor. Yang thanked me for my info but that was the last I heard. I have been in cotact with Johnls in the mother country and he has 20 flights on the original components but feels that he may have to strip them down and inspect or modify.

As I mentioned to John, the life of the "shuttle" system will be directly related to the ground you are running on, a grass strip will accelerate the wear dramatically compared to a tar runway.

That being said, it is still a great plane and a very strong UC but I think I will end up taking out the locking system and convert mine to hydraulic.

I look forward to seeing some pics of your girl when it arrives.
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Old 08-23-2010, 04:06 AM
  #53
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Default RE: Jetlegend Mig 29 Fulcrum

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ORIGINAL: F15driver

Bart,

I read with interest your issues with the landing gear retracts. My Mig 29 should be delivered in a few days and I was hoping that your comments inspired JL to modify its mechanism to a stronger metal. Have you heard of any updates to their retract? Did you pass on your repair to JL?

Look forward to your comments.

Rob
F15driver
Rob. If you see that the U/C has improved, please post on here. May be difficult to know if you haven't seen the old version though.

Shane & John. Thanks for your pm's.
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Old 08-23-2010, 01:10 PM
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Default RE: Jetlegend Mig 29 Fulcrum

Bart,

I would be most interested in your hydraulic conversion. Will you please keep me posted on your fixes to the landing gear system? I'm not altogether surprised you haven't heard from Yang at JL. Communication is definitely not their strong suit. My "to be delivered" Mig 29 is a replacement for the destroyed F-20 that JL finally acknowledged was incorrectly engineered. As you know, that little debacle only took JL 3 or 4 months to come to grips with. My F-20 crashed in March and I've yet to receive the Mig as a replacement. JL has indicated through my dealer that it should be delivered around the end of this month. We'll see.

Best regards,
Rob
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Old 08-23-2010, 02:33 PM
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Default RE: Jetlegend Mig 29 Fulcrum

Jascat,

Will do. Hopefully they've strengthened the one part mentioned by Bart in his fix.

Regards,
Rob
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Old 08-24-2010, 03:49 AM
  #56
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Default RE: Jetlegend Mig 29 Fulcrum

Rob

We have our main event (Temora, NSW) coming up in a couple of weeks so it won't be converted till after then, but I will post the info here when I do it.
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Old 09-21-2010, 01:12 PM
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Default RE: Jetlegend Mig 29 Fulcrum

At Jetpower I was told by Mike (Global Jet Club) that JL will now make the locking pin out of steel to avoid the issue. Thnk kits with these modification from November.

Looking forward to details on the hydraulick conversion
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Old 09-21-2010, 04:49 PM
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Default RE: Jetlegend Mig 29 Fulcrum

I also spoke to Mike, at Jet Power, and was told the same. The changing of the internal shuttle material will lengthen the life of that component. Mine was showing wear grooves even before I first flew it, and with excessive wear the ball bearings will not travel out enough to lock the wheels down. I have other issues though that are not being addressed. The length of the stroke of one of my main cylinders was wrong, allowing the ball locking mechanism to travel past the corresponding groove it should locate in. This meant that often the gear would be stuck down because the locking balls were jammed in the wrong position. I fixed this by putting a shim in the end of the cylinder to ensure the ball bearings/shuttle stopped in the correct position to locate in the outer groove. The other problem is that there is no uplock for the main wheels, even though there is a machined groove and provision to fit the corresponding ball bearings to allow this. Why this is omitted I do not know, I also note from Shane's (Aussie Bart) photo's that his is the same. The main wheels therefore fly out having forced past the gear doors. I have decided that mine is unflyable, after 18 flights, until fixed. I too am investigating converting to a hydraulic system. Issues that will have to be overcome is the small size of the retract cylinders and the corresponding small in and out nipples (space is a premium). The internal shuttle system can then, hopefully, be ditched. I will allow Shane to take the lead in the conversion as he has experience of hydraulic undercarriages.


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Old 09-22-2010, 06:57 AM
  #59
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Default RE: Jetlegend Mig 29 Fulcrum

The flights at the recent Temora meeting were problamatic as the nose wheel would refuse to retract when the plane was flying due to the back pressure caused by the airstream (works fine on the ground). Unfortunately just fixing the shuttle material will not remove the problems as the next weak link is the brass lining in the cylinder barrels, this just starts to flog out where the locking grooves are, definitely NOT a long term design.

As for the up locks, they won't work as the load (gravity at least) on the gear when it is raised will stop the locking balls from releasing and thereby letting the gear down.

In my opinion, the only way this will work is to fit a simple hydraulic system such as supplied by UMS in India and remove the locking balls alltogether, the hydraulic system will hold the gear both down and up and is non-compressable.

I already have these in my Vampire, JL T45 and Tigercat (has props so probably does not count) and they work FINE. You can raise or lower the UC as many times as you want during the flight and you get exactly the same function everytime.

I will start the Mig conversion in a couple of weeks (away with work at present) and post the results here. There is no doubt that the scale function created by hydraulics looks great!! the sight of my Vampire wheels retracting at scale speed just after the wheels clear the deck is a wondefrul thing to see.

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Old 09-22-2010, 07:47 AM
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Default RE: Jetlegend Mig 29 Fulcrum

Bart,
All JL Mig 29 owners are very interested in your conversion of the gear to hydraulic operation and look forward to your future postings. I'm still awaiting delivery of my Mig but I understand its now scheduled for Oct. 15.
Rob
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Old 09-23-2010, 07:13 AM
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Default RE: Jetlegend Mig 29 Fulcrum

Rob

The Mig is great (and 4 kgs lighter than the SM version) but the tricky stuff in the gear is just not worth it. I promise you the the hydraulic system is easier, more reliable and only about 200 grams heavier, it is well and truly worth it.
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Old 09-23-2010, 11:46 AM
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Default RE: Jetlegend Mig 29 Fulcrum

I am very interested in the Hydraulic switch as well since I have the JL SU-27 and the gear is very similar. I saw all the parts on the UMS website and the prices were VERY reasonable. The only thing I thought was weird is that there was no accumulator which I thought was kind of an essential piece to hydraulic systems. Anyways, can't wait to see the mod!
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Old 09-23-2010, 07:38 PM
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Default RE: Jetlegend Mig 29 Fulcrum

Is this the UMS system?
[youtube]http://www.youtube.com/watch?v=PVtgUJvn4uI[/youtube]
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Old 09-24-2010, 07:15 AM
  #64
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Default RE: Jetlegend Mig 29 Fulcrum

Edgar
Yes that is the UMS system (that vision also shows their retracts) that primarily consists of a Hydraulic Pump, 2 position 5 way directional valve (operated by a mini servo), Reservoir with internal clunk line and a Controller that senses end of stroke due to current rise and shuts the pump off.

Eurokit from Italy make a system that looks almost exactly the same but still different, even the microchip from the controller is the same and interchangeble but the UMS version very much cheaper and IMHO is much better..
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Old 09-24-2010, 09:45 AM
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Default RE: Jetlegend Mig 29 Fulcrum

Interesting as it is very cheap, is the UMS system a rip off from the eurokit?
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Old 09-24-2010, 10:09 AM
  #66
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Default RE: Jetlegend Mig 29 Fulcrum

Bart,

Very interesting system. As I understand it, the hydraulic pressure will hold the legs either up or down without the need for a locking mechanism at either end? What provision, if any, is made for the gear doors? Do you still need a whole separate system with air pressure for them or is there some way to use hydraulic pressure for them as well?

Will look forward to your response and conversion.

Regards,
Rob
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Old 09-24-2010, 01:22 PM
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Default RE: Jetlegend Mig 29 Fulcrum

UMS don't seem to be the fastest company to deal with. I paid for a hydraulic conversion set on the 28th August and it still hasn't been dispatched, I look forward to receiving it so I can get flying the Mig again.


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Old 09-24-2010, 04:10 PM
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Default RE: Jetlegend Mig 29 Fulcrum

John,

Will you be removing the ball bearings on all 3 retracts and thus rely on the hydraulics to lock the gear up and down? Any previous experience with this type of set-up? What will you use to sequence the doors with the hydraulic retract system?

Regards,
Rob
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Old 09-25-2010, 01:59 AM
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Default RE: Jetlegend Mig 29 Fulcrum

I am in contact with Shane (Aussie Bart). I, personally, have not done a hydraulic conversion before so I will be looking to Shane to take a lead here. I have also spoke to Mike Burrell, in the UK as he has several models all flying faultlessly with hydraulic conversions (in Mick's case of his own design). I will be removing the ball bearings for sure, they are the root of all the problems, creating wear and jamming. They are also not needed,as the hydraulic pressure will hold the gear in place. When Mick looked at my gear he commented that all his set ups have a 4mm hydraulic line to the cylinders, the JL gear has a 2mm nipple and there isn't enough material to get a 4mm nipple into. Also the overall size of the cylinder is small. It is worth noting, however, that Mick uses a thin Citroen car hydraulic fluid whereas I will be using Sewing machine oil which is thinner. As for the door sequencing, I haven't finalised how this will be done. I have a Jettronic door sequencer, and a possibility is to use this with an air set up, another possibility is some form of micro switch activated circuit. I will post here as things develop. I am committed to get it working as I think the existing setup will never work reliably for any length of time.



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Old 09-25-2010, 07:06 AM
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Default RE: Jetlegend Mig 29 Fulcrum

John,
Thanks for your post. Very informative. Will await your further results.
Rob
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Old 09-25-2010, 03:23 PM
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Default RE: Jetlegend Mig 29 Fulcrum

Hi Rob

As John mentioned, the hydraulic system will hold the gear up or down until the cows come home, this is due to the check valve placed on the pump outlet. The only point of failure can be if you blow a line off a fitting, to reduce the risk of this I use good quality Festo 3 mm airline tube and add a small lockwire over the tube and nipple connection.

John, don't stress too much about the fitting size on the cylinder. The supply line from the pump to the directional valve is 4 mm and this flows oil perfectley. After the valve you split the flow into effectively 3 directions - one for each leg. The internal combined area of 3 x 3 mm air lines is just over twice the size of a single 4 mm line. The combined area of the hole through the nipples on the 3 cylinders is 25% more than the 4 mm line, so the greatest restriction is in the 4 mm line.......(I am a hydraulic engineer by profession). The best tip I can give anyone with hydraulc gear is to use sewing machine oil.

I hope to be able to get onto this mod in about a week or so as I am still interstate commissioning a 35 ton wood chipper that is fitted with a 30 lt (1,830 cu.in) 1000 hp V8 diesel, and yes lots of hydraulics and electronics that I supplied.

Talk to you guys soon.
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Old 09-25-2010, 03:31 PM
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Default RE: Jetlegend Mig 29 Fulcrum

Forgot to mention. You still need air for your brakes, so use the same tank for your doors. In the other planes with hydraulics I still use a sequencer and connect up the hydraulic system and door system exactly the same way you would if you were only using air. The hydraulic controller has an input servo lead that triggers the pump to run everytime you cycle the gear up or down.

UMS can certainly be a bit slow, however I have bought about 7 kits from these guys in 3 shipments and the stuff has always arrived. In Aus, we are used to waiting to get stuff so it seems normal to me. You guys who are in the wrong half of the world are spoilt with all the countries and resources you have close by.............
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Old 09-25-2010, 11:40 PM
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Default RE: Jetlegend Mig 29 Fulcrum

Very interested in the step by step conversion process. Lots of pictures and explanations in dumbed down speak for me please.
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Old 10-20-2010, 05:00 PM
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Default RE: Jetlegend Mig 29 Fulcrum

I ordered my UMS hydraulic kit the other day and they said it should be shipped by the 25th. I have not even flown my SU-27 yet and will not do so till this mod is done. Should be simple enough and I am looking forward to flawless gear!
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Old 10-20-2010, 06:38 PM
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Default RE: Jetlegend Mig 29 Fulcrum

I just received notice from Jet Legend that my Mig 29 was enroute so I too ordered the hydraulic kit from UMS. No delivery date promised yet. Keep everyone posted on the installation of this system in your Mig.
Regards,
Rob
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