Zagzoo

My Feedback: (28)

I don't know if I read it or not (been reading a lot on this lately), If I use the battleswitch, what turns the pump off when the gear lock up or down?

Thanks for the info...

Jgwright

Frank

The pump is switched off by the pressure switch which cuts the neutral line to the servo switch when the pressure reaches the required level. If you program your radio you can if you want have the signal to the battleswitch not active until just before you want to lower or raise the legs and cut off when the legs are up.

Bob

If you let me have your wheel size, and leg length from the pivot to the axle I will compare with mine. I would also need the approx size of the cylinder (diameter and stroke) to compare with the Behotec C50 ones I am using.

John

Blancr

Thanks John - will have to get back to you on that when they arrive unless anyone with a similar aeroplane can help?

Thanks

Bob

extra 300

My Feedback: (3)

John,

Thank you very much for your time and input. Appreciate it very much.

Kind regards,
Dany

Roy Hanouka

With regards to the oil reservoir tank, can either gasoline-type tanks or kerosene-type tanks be used? In other words, I assume there are no issues with the hydraulic fluid reacting with a particular type of tank?

ww2birds

My Feedback: (14)

Great thread and many thanks to John for sharing his implementation.

Anything special about the Eurokit valve? Are there other alternatives that can be made from more typically available spool valves? Could you just add a fitting to the vent hole of an air retract valve and run it back to the low-pressure reservoir?

I checked the Eurokit webshop and saw the wing quick connects, and the "aluminum pump clutch" (wonder what that is) but did not see a way to get the valve a la carte.

thanks
Dave

Mark Vandervelden

Hi All

I tried to order the Eurokit 5way valve from "Airfighter" Monday but im sorry to say that there out of stock and not likely to have any more in.
Im going to have a go at finding some of the UMS ones, if I have any luck ill let you all know.

Mark V

ww2birds

My Feedback: (14)

If the EK valve is going to be hard/impossible to get .. perhaps if we could spec the schematic of the fluid flows we could request some custom parts from a company like Ultra-Precision (I don't know if they do custom work, we can ask... they make really nice stuff!).

Dave

Mark Vandervelden

Hi all

Just made a pre order from http://www.eurokitshop.it/ for the valve @ 31 euro, 200ml oil @ 23 euro and tank at 19.50 euro and postage from Italy to the UK @ 25 euro.
Payment is via Pay-pal and im waiting for a confirmation email/request.,
There seems to be free postage if the order is over 150 euros, anyone want a valve or two and split/reduce costs?.

I have also inquired at UMS direct as I've ordered from them before, they will sell 10 of there valves at just under 9 euros each plus what ever shipping and taxes come to.
I will ask if they will send smaller amounts unless theirs a lot of interest out there?

Jgwright

Dont Panic too much about the valve. It is really nothing special it just has not to leak. The UMS one seems fine and as Mark has found can be bought from India. I had an old spare Robart valve and checked to see if I could use it as a hydraulic valve. I removed the aluminium rod after removing the circlip. I then carefully drilled out the air holes to 1.3mm and you can just see them in the photo. I then drilled out the entry holes to 2.5mm and tapped 3.0mm. This has to be done VERY carefully as you do not want the 2.5mm hole to go right through. I then made sure that there was no burr in the inside that might damage the seal when the rod was put back in. I screwed 4mm festo fittings and inserted the rod and circlip. I then tried it out. It worked well enough to use, but there was a slight weep out of the end between the rod and the sleeve. Now this was a very old and very used Robart valve and it may well work fine with a new one.

John

Justflying1

Hi John,
with the pressure switch is this pressure adjustable or is this permanently set.

Jgwright

The pressure switch is adjustable by turning the screw in the end, you can adjust the pressure to make sure you have enough surplus force to guarantee the legs will come up.

John

Justflying1

Thank you for the info John. Seems like you have a very good reliable unit there.

Skyline-Hobby

This is a very good idea!!
May find another choice between air and electronic!!

David Gladwin

A little extra which might help.

My main experience with hydraulic (model) systems is on my FC Mig 29. I eventually got the machine airworthy by using the Omega system and the model flew with that system. However, retraction and extension speeds of the gear were far too long and even upping the pump voltage to maximum didn't help much, it was still too slow. I am now reworking the hyd. system on the Mig using the Festo heavy duty 4mm tubing and, Eureka !

The original black tubing supplied with the kit is very thick walled meaning the internal bore is tiny. The Festo tubing (rated at 35 bar, 500 psi) is much thinner walled and of almost twice the bore meaning the flow rate, at a constant pressure should be MORE than double. That SEEMS to be the answer to the speed problem. I don't know what the pressure rating of the original tube is/was but I did have a couple of bursts, the Festo should fix that too.

Concerning selector valves, Peter Hausl (of pump fame) makes some very nice servo operated valves which are around 40 Euros each, just received 4 for my Mig, (http://hptech.at)

Most airliners have two pumps on each of 3 hydraulic systems, on the B767 one was engine driven, the other air driven (one pump failure means things move, even at half speed.) So on my Mig I will be using two pumps in parallel (one will be an old Hausl fuel pump) with an alternate extension system using my design of air from a separate air tank at 200 psi. Should give the maximum protection against failure, wheels up landings on the Mig are not pretty, I hear !

As for the pressure switch, I still think Mick Bs idea of a spring loaded cylinder is elegantly simple, and arguably the most reliable. (Like John W I use old Robart cylinders with springs intended for Air World Hawk landing gears, cut to length so that the rod reaches 3/4 travel at 150 psi and this is also being incorporated into my Mig system.

Hope this helps.

David G.

Jgwright

David

Glad to hear that you have your system operating again and the Mig might be in the air soon.

John

David Gladwin

Thanks John, it certainly is a fine flying machine. If you would like some HD Festo tubing I will send you a couple of meters.
David.

DiscoWings

My Feedback: (76)

Alright well my little DONKEY ums pump finally killed itself... sadly this pokey couldn't even lift 1 gear much less 3 so now I"m looking for a strong micro pump that can supply 200 psi or so, this first pump couldn't even do 40 psi despite the 10 bar claim it had.

IF anyone has a good source for small pumps, please share!

Jgwright

Any standard turbine pump for 100N should be able to deliver, so any turbine manufacturer. Do you not have a spare pump you can try? I used a Xicoy brushed pump.

John

Jgwright

David

Thanks for the offer but I have a supply of my own now.

John

mr_matt

My Feedback: (10)

David what is the ID/OD of that 4mm tubing? Can you provide a Festo PN? Thanks so much in advance,

David Gladwin

[TABLE="width: 800"]
[TR]
[TD][TABLE="width: 100%"]
[TR="bgcolor: #E9E9E9"]
[TD]PAN-R-4X0,75-SI Festo Heavy-duty tubing (50m Coil)
Product Code:EF541674[/TD]
[/TR]
[/TABLE]
[/TD]
[/TR]
[/TABLE]
The 4mm tubing OD is 4mm ! See Festo spec. sheets for exact internal diameter but the wall thickness is quite thin compared with the previous tubing I had.

Looks fine for fuel too as it is semi transparent. It was 72 GBP per coil

The product code may be that of my UK supplier.

David.

Jgwright

A thought just occurred to me, I hope you have installed the non return valve the correct way round?

John

DiscoWings

My Feedback: (76)

yes the one way was on the outflow on the pump prevent the oil from going back into the pump

David Gladwin

Pleased to report that I have re-plumbed the landing gear circuits on my Mig using the Festo HD tubing. Double checking each cut to ensure its square has resulted in NO leaks and a fully operational system.

The system is now a hybrid using the Hausl pump, (on a 3 cell lipo) with a JetTronics gear sequencer closing the locking valves, works very well, in fact after extensive testing, the gear is now airworthy.

Retraction time is still rather slow at 9 seconds on the Hausl pump, a second or so faster with the UMS pump which leads me to believe that volume output from the pump is as important as pressure.

Timing is slightly shorter using the UMS pump which tends to confirm this and when connecting the UMS pump into the output pressure line in the Hausl, downstream of the NRV, the Hausl pump cut-in frequency was much lower than normal suggesting that the EUMS pump output is slightly stronger than the Hausl.

Still, the Mig needs nose ballast so installing a second pump creates real redundancy and replaces some chunks of lead !

I have ditched the UMS controller (for now) and will use John Wright (and Mick Burrel )'s system for pump control.

As usual EVERY component was checked for leaks before installation, one or two leaked air but were completely leak proof when tested on hydraulic fluid.

Looks like the Mig will be airborne again soon !

David.