Aussie Bart

Hey Lior

I was just looking at the photo's you posted earlier on the upgraded gear and I don't think the hydraulic conversion I have done will work with this "fixed" design. My thoughts are that the oil will try and extend the main cylinder before it unlocks the locking cylinder, this will just cause it to jamb. I believe you would need the original gear.

i3dm

My Feedback: (51)

Why will the oil move the long (non locking) cylinder before it moves the short (trunion) one ?

Also, if thats the case - i can disconnect one of them, make it a dummy and use just one (either of them) to run the mains. your hydraulic system has essentially the same long cylider as my new LG. so perhaps cancel the short locking cylinder all together ?

I have been discussing this for several times now with Ron Word from Down And Locked - he is one heck of a nice guy ! he has pics and explinations about the problems, and is trying to find a proper solution. after talking to him for several times i can ssure you he thinks outside of the box - it was a pleasure dpeaking to him indeed. we'll know soon what he is coming up with.

For now, just for kicks i pumped my system to 100 PSI. it is so easy to retract the (un locked) nose gear that its not even funny, i think a simple applyment of brakes upon landing would collapse it.

i3dm

My Feedback: (51)

Well, after several long conversations with Ron Word from Down and Locked, and emailing pics and sketches back and forth - Mitch and Ron have notified me that although it would require sagnificant changes from their stock system, they think they could convert this LG system to electric with a controller that will also sequence the (still air operated) gear doors.

I have been asked to send in my LG to them, so tommorow the LG comes out of the MIG and off to the US to DnL.

JohnMac

Well just to add another idea into the mix incase we don't have enough already, why not use a standard retract on the nose gear, Surely this could be done (assuming that one would fit, but I do not see why not) utilising the JL legs and wheels?

johnls

I would say it would be impossible to fit a standard retract system, without spoiling the looks of the model. The landing gear is quite scale like and, in my opinion looks much better and authentic than the Skymaster gear which is standard. The nose leg not only retracts but self centers and shortens whilst retracting.
I have just re-installed my hydraulic system using some new pistons I have machined up with new rubber O rings and the the festo non return valves (that Shane recommended). So far it goes up and down perfectly and is rock solid. Fingers crossed it is like this in the morning.



John

Pepperpete

While I can appreciate trying to maintain the scale looks, I would much rather have a 100 percent hassle free landing gear set. After going through the landing gear disaster which is the FEJ F-16, it really soured the mood. I am "THIS" close to pulling the trigger on this Mig but with the gear problems it's really putting a damper on it.

Aussie Bart

JohnMac
Love the thought, but as Johnls commented, the critical function of the leg is that it folds the wheel up quite away. You would either need to move the nose mount forward or cut through the bulkhead where the nose section joins the main body section.

Johnls
Glad you got it together, might help the other guys if you could post some photo's. Did you fit the Pilot Check Valves??

Aussie Bart

Don't pull the pin yet, give it another week to get some feedback from the other guys as they do their mods. The Mig is such a nice plane that you may always regret it.

Try not to think of the gear as just being faulty, think about the hydraulic upgrade as being the ideal system for this plane, the extra benifits I believe are worth it. My only regret is that I did not do the mod on day 1.

Rider-60

My Feedback: (17)

Guys I follow this thread and find it very interesting since I plan to convert another plane to hydraulic gear. However the UMS system seems to be far from reliable.
Does any of you have considered the Mig 29 gear actuators from Matrix? it is an air retract though....but might save some headach
http://home.earthlink.net/~matrixmt/id13.html

johnls

Well it been 36hours now and the undercarriage is rock solid and works correctly. I feel confident enough to run up a flag and pronounce IT WORKS!!!. The pilot check valves definitely make a difference and are worth fitting. I must say a big thankyou to Shane (Aussie Bart) for his guidance and support because without his expertise, regarding hydraulics, I would still be being frustrated with ball bearings etc. The total weight added to the aircraft is negligible and the end result is stunning and strong. I am now re-installing my engine etc. and look forward to some decent weather to get this thing in the air again.
Here is a video on the operation and I must add that the pump operation is very slow due to my battery needing recharging.
http://www.youtube.com/watch?v=fzziQtdRu78





John

i3dm

My Feedback: (51)

Shane, would like your input on this:

Why will the oil move the long (non locking) cylinder before it moves the short (trunion) one ?
Also, if thats the case - i can disconnect one of them, make it a dummy and use just one (either of them) to run the mains. your hydraulic system has essentially the same long cylider as my new LG. so perhaps cancel the short locking cylinder all together ?

i3dm

My Feedback: (51)

I guess i might have spoken too soon about the elctric conversion. on the mains DnL wanted to install their motor in the trunion cylinder assembly, as there's hardly any room to do so in the long cylinder since its a tight fit in the fuse, and has a very long stroke.

Anyway, i took one main gear out and noticed that as the trunion assembly is originally designed as a locker only, is flimsy and thin. I could only see this after pulling the gear out. I think having the loads of this big strut on such a small aluminum piece is impossible.

Back to Hydraulic ? im thinking about cancelling the locker and using hydraulics in the long cylinder only - that would be just like how you guys modded yours, wont it ?

For those who have done the Hydraulic conversion, i went back and looked and there was some confusion about the Feso bits needed for this conversion - can anyone make a list of exactly whats needed (pilot check valves etc) with part numbers ? i could just order all of that from the local Festo dealership im sure.

johnls

Lior
You can convert this to the earlier version by simply discarding the small cylinder. The main cylinder should be 10cm (4 inches) long. Take this apart to check if the pistons inside have holes in them or are solid. If they are solid then no further modification is needed. You will need 3 Festo HGL M5 QS-4 check valves with QSM-M5-3 adapters, a pump, 5 way valve and sequencer (UMS can supply these, I have had three and got one to work correctly, at least they are cheap!) or instead you can make up a mechanical shut off so that a microswitch is triggered when the gear reaches the end of its travel. The gear doors are still operated by air. Your can use a jetronic door sequencer, or as I have , program a delay via your transmitter. Now I know how to do it the conversion would not take very long, especially as your model is new.

Hope this helps,


John

i3dm

My Feedback: (51)

John,

How many units of the QSM-M5-3 are needed ?

I do see a point of light with the fact that this (newer) version can be converted to Hydraulic without needing any parts machined - the stock long cylinder now has an inner shuttle with no holes so thats a good thing.

I think i will go with the EuroKit Hydraulic conversion - i heard theyre very good, and this plane does deserve the best.

So - here are pics of the landing gear without the small cylinder, as they will be converted to hydraulic.

On a more personal note - it is definitely disappointing having to mod the original LG of a new model, but with Chinese ARF's this is not something out of the question. most of them require mods to get right. the good point is that the conversion is not very expensive, and not very complicated and what i liked best - it does add a touch of realism as i believe the real thing uses a hydraulic system also, and the speed of the gear becomes more scale too. bottom line is - this model is so nice (!) and priced right even if you count in the cost of the Hydraulic conversion.

johnls

You need three QSM-M5-3. These convert the threaded outlet to a 3mm push fitting. I agree with your sentiments regarding having to convert the undercarriage on a new model. It makes you wonder how they are tested in the first place. Best if luck with your conversion.


John

i3dm

My Feedback: (51)

John,

I think some 4mm to 3mm reducers are required too if i remember correctly ?

ianober

My Feedback: (12)

I would be open to this but only if the price is right but I have a feeling that this wont be the case. I am not sure about anyone else but I am sick and tired of getting $1000 landing that needs $350 worth of parts from some other company to make it work.

I am sure they can do it but it is not going to be cheap which is why they wont sell many of them. This sucks!!![:@][:@][:@][:@]

johnls

Yes they are, I was taken that as read. You need 3x 4-3mm reducer, 2x 4mm 4 way connecters, 3 x 4mm 3 way connectors, and a one way valve + the 3 x MGL M5 QS-4 with 3 x QSM-M5-3 connectors.

Get ordering.



John

Aussie Bart

John

Love the Vid and congrats on the conversion, although I feel you will need to put DOUBLE lock wires on the nipples if you truly want to use the mother in law test rig........ As part of your routine maintenance, always keep an eye open for oil deposits in or around the fuse. This hydraulic system is fully sealed and as such the only way oil can get out is if it leaks.

Also love what you did with the 14MZ, it is certainly a nice solution as I had trouble finding a sequencer that would give me enough time from gear up signal to doors close. The one I have at present does it but I have the same time door open/gear down to gear up/door close, so as you come into the upwind leg and drop the gear, there is a sense of aprehension as you see the doors open and then wait what seems like a long time for the legs to start popping down. Once I get the A10 out of the way I will have a look at doing the same on my MZ.

Aussie Bart

Lior

Oil (lust like air) is extremely lazy, it will just flow to what ever is the easiest path first, it is also true (one of Pascal's laws) that the oil pressure will act upon all surfaces within a closed chamber equally. When the 2 cylinders are connected by a common line, they are effectively a closed chamber that see the same pressure at the same time. Therefore I believe that the main cylinder would start to move due to it being bigger in diameter and requires less pressure to move and only once the main cylinder movement is restricted (pushing against locking trunnion) then the lock cylinder will have enough pressure to move but by then the main may be jammed up. For it to work successfully on oil, it would need a sequence valve.

When operated by air which effectively has nill viscosity, the compressibility slows down the reaction and acts just like springs, thats why gear snaps up or down if not throttled.

i3dm

My Feedback: (51)

Shane, both cylinders are of the same OD. but i have to disregard the locking one anyway in order to duplicate your (lockless) system.

lavi rider

My Feedback: (6)

People,

Give MTH Pumpen a call they should have a fully developed system.

F15driver

My Feedback: (24)

UMS has come through...

As previously posted, I burned out 3 UMS controllers due to their having used an inferior grade capacitor in the control box. I corresponded with them via email and requested they replace 2 of the controllers with new units with an upgraded capacitor. I was able to repair the third controller with a new capacitor from Radio Shack. Today I received 2 new capacitors in the mail from UMS at no charge. After soldering on connectors and plugging in a new controller, I activated the switch while standing ready to unplug the battery if the new controller showed any sign of overheating. All went well in my test stand and I cycled the retracts 3 or 4 times to make sure there would be no problem.

I have to hand it to UMS. A problem was called to their attention and they proceeded to take care of it with no questions asked. Originally they offered to send 4 new capacitors for me to replace the burned out ones but 2 of my controllers were so bably scorched in the area of the capacitor that other damage was likely. After I requested they ship me 2 new ones, they did so with no questions asked. KUDOS to UMS! I wish our Chinese supplier of the Mig 29 had even a small dose of UMS' customer service. One could only wish...

Rob
F15driver

ianober

My Feedback: (12)

Nice, I will have to remember to open my controller and check it before I apply power to it.

i3dm

My Feedback: (51)

My hydraulic kit is on the way from Eurokit, and ive sent an enquiry to Festo Israel for a price offer. fortunately they do offer each part in any desired quantity rather than 10 packs. lets hop their price is right too