Hydraulic Retract question
 

Hey everyone I ran across a conversion at hobby king and I have seen these before it looks like I nice alternative to air and a LOT cheaper than electric conversion.
I was wondering if anyone has used the hobbyking version I did see one review for a FEJ f15 using it but not sure what size.
If I tried a system like this can I run everything like my gear doors on it as well? im trying to come up with a system that doesnt require so many different things.
I refuse to use air for my landing gear but its fine for doors, canopy, brakes and stuff like that. I like the electric gear but converting 9 gear doors to electric and speed brakes to electric would just be crazy so I figured this may be a better alternative.
You can use it for brakes and you just use your current air cylinders, I would probably have to get a bigger oil tank for all the extra parts.

just some feedback from people who use it now.

RE: Hydraulic Retract question
 

link?

RE: Hydraulic Retract question
 

Just go to hobby king and look under retracts

RE: Hydraulic Retract question
 

Do a search on the jet legend mig29, I remember reading a thread, doing a conversion with the system you are talking about...

RE: Hydraulic Retract question
 

Okay thanks will do

RE: Hydraulic Retract question
 

Here is a link

http://www.hobbyking.com/hobbyking/s...Retracts_.html

looks good value for money but it will add quite a bit of weight

RE: Hydraulic Retract question
 

I have been extolling the virtues of hydraulics for years now, I have five models which have been converted I don’t have the slightest problem with any one of them, one in fact is a quarter scale Jerry Bates Sea Fury has hydraulic landing gear wing folding mechanism and hydraulic doors.

The system depicted in that picture is the UMS system from India, the price looks comparable with what you would pay direct from the factory. In my view it has one weakness and that is the ECU, so I did away with it and made a simple accumulator from a discarded U/C ram, this ram has a spring fitted to the air/rod side (this spring determines the switch off pressure) the rod operates a micro switch which controls a radio controlled relay which operates the pump. This system is utterly reliable and doesn’t leak!

Right now I am flying the 1:7 FB F15e which has hydraulic gear and doors, the gear system has been converted to 4mm pipe and unions the doors are still 3mm and work perfectly. You can get away with two valves if you leave the doors open gear down although mine has three valves to enable three doors to close gear down. You can use a two cell LiFe (A123). I use a three cell which gives good speed and you won’t overheat the motor as it only runs for 7-9 seconds. The other good thing is I can get 30to40 cycles from one charge and the up and down speeds are the same.

If anyone is interested I can go into much finer detail as to how the transmitter is set up.

m

RE: Hydraulic Retract question
 

Mick15,

You're doing a great job. Would definitely like to dig deeper in this avenue. I am still undecided whether i should go electric or hydraulic on the gears and doors. Do you have a photo of your mod on the hydraulic system?

Thanks,

RE: Hydraulic Retract question
 

I'm planning to use hydraulics on near everything possible on my F-14. Gear, doors, Slats, Speed brakes, etc. The systems weight a bit more, but the fact that the speeds are near identical each direction and as long as all the air is out of the system, everything should work simultaneously is a big plus

RE: Hydraulic Retract question
 

If converting from air - You cannot use electronic valves like like Air-Power etc. can you?

RE: Hydraulic Retract question
 

Yes Mick15,
if you can show the transition between 3mm and 4mm, are you using festo fittings or similar?
also, are the barb fittings on the cylinders up to the task?

thanks

RE: Hydraulic Retract question
 

mick15

I am building an airworld gripen and the gear is set up for hydraulics. I am not married to the hydraulic system that came with the plane and would be interested in your setup. Curious hat the problem with the ECU was and more detail on your substitution

RE: Hydraulic Retract question
 

tow, totally impractical I don't think they would last long with oil in them. Incidentally I run Citroen LHM hydraulic oil in my system.

loucel, picture shows relay used and Festo for retract cylinders 5mm thread 4mm hose. Barb fittings are more than adequate, the system uses around 160psi although these pumps will deliver 275psi so be careful you can burst the neoprene hose, that's why I use nylon hose.

roy, I did have two of the ECUs fail and because they rely on pump amperage feedback they are inconsistent, plus the fact that with my system you can control it from the transmitter, I have a timed delay to run the pump plus an override switch so the pump can be run at your demand.

The second picture shows the accumulator and micro switch, the switch interrupts the negative wire to the relay so when the micro is "open" the relay is inoperative.

m

RE: Hydraulic Retract question
 

mick 15,

thanks for the info, very helpful....

RE: Hydraulic Retract question
 

Interesting, so your system with this accumulator and microswitch is designed to shut the pump down at some certain pressure so it does not over pressure the system or the pump keep running?

RE: Hydraulic Retract question
 

So if I wanted to do a full setup, gear, doors, speed brakes and flap/slat how much weight would it add compared to air?

RE: Hydraulic Retract question
 

roy, you need to remember the transmitter determins when you get the pressure and the accumulator determins how much. It is also true that because the accumulator has a reserve of pressure U/C mechanical up and down locks are rendered unnecessary.

All things considered the extra weight is in the order of 8oz which is the weight of the pump, the valves, the pipes, the cylinders and the oil tank are present anyway.

m

RE: Hydraulic Retract question
 

hi:

But, one question ! you can use the Hobby king system in any retracts ??? or it is only for little retracts ???

BR from Spain.;)

Carlos Márquez.
____________________________________
http://www.cmjets.blogspot.com/

RE: Hydraulic Retract question
 

Yes any size is doable. Ihave hydraulics in my boomer XL and in my 1/4 scale SeaFury.

m

RE: Hydraulic Retract question
 

Hi Mick::)

Thanks for your fast answer. And... I need make something to my LG ? really i can run it in hydrulic version withow change nothing ?

BR.;)

RE: Hydraulic Retract question
 

Well not quite. you will almost certainly need 4mm tubes.

m

RE: Hydraulic Retract question
 

Hi Mick::)

I will change the 3mm festo plugs to 4mm. O.k. Many thanks. I will try it.

BR from Spain.
Carlos Márquez.
____________________________________
http://www.cmjets.blogspot.com/

RE: Hydraulic Retract question
 

Mick would be very helpful if you could provide info on the specific accumulator you used, where it can be purchased, and a wiring diagram for how you rigged this up. Roy

RE: Hydraulic Retract question
 

So...If you blow a line or fitting you have oil, not air, all over the inside of your model? [:'(]

RE: Hydraulic Retract question
 

Correct.

M