Do It Yourself?
05-13-2014, 02:50 PM
#1
Thread Starter
Do It Yourself?
Hi,
Anybody here done DIY hydraulics on the Y/A F-18? I mean the struts, not the retraction. If you did it, how did you do it and how did it work out?
Anybody here done DIY hydraulics on the Y/A F-18? I mean the struts, not the retraction. If you did it, how did you do it and how did it work out?
05-13-2014, 05:27 PM
#2
Smokin joe mcbride did it with his. I did it on both of mine using small orings, that fit the grooves on the lower strut, from the industrial hardware store near miramar.
I used a 10-32 muffler tap on the upper strut and Tygon tubing feeding a small one oz round tank with thin/ light car shock oil.
Worked great and although not as good as joe's it dampened the landings adequately for my needs.
I used a 10-32 muffler tap on the upper strut and Tygon tubing feeding a small one oz round tank with thin/ light car shock oil.
Worked great and although not as good as joe's it dampened the landings adequately for my needs.
05-13-2014, 05:35 PM
#3
Thread Starter
THanks, Buck.
Did you have to polish the inside of the tube? Mine feels rough enough that I think the oil would leak through over time. With your tank, how did you plumb it? How did you purge the air out of the system?
TIA
Did you have to polish the inside of the tube? Mine feels rough enough that I think the oil would leak through over time. With your tank, how did you plumb it? How did you purge the air out of the system?
TIA
05-14-2014, 03:01 PM
#4
You r welcome amigo, happy to help. It's not a perfect seal but the primary goal of this setup is to help dampen the tendency of the mains to " dance " in a crosswind and soften the landing a bit on the airframe.
I tried antifreeze but found it to be too thin then experimented with various viscosity RC car shock oil. I found the 10-15 wt oil to provide the best dampening effect while allowing the springs in the mains to extend the legs fully, thus not interfering with gear doors during retraction. Too viscous and it takes too long to extend too thin and the gear dampening effect is lost.
a 1 oz round Dubro tank plumbed with a 3 line setup and some Tygon tubing is all you need, in addition to the 10-32 tap on the upper strut.
You wIlll need hemostats to clamp off the line when not in use.
Envision a 3 line Dubro stopper in the 1 oz tank configured as such:
fill line ( easily accessible Tygon with plug )
vent line ( brass tube extending straight and all the way to back of tank ) then a Tygon line from the exiting brass tube to an overflow location bottom of fuse
feed line to the upper strut ( this brass tube barely exits stopper inside tank )
Meow you should be holding a standard glow tank with the following exception....the vent line and feed lines are reversed in the traditional sense. The reason I say this is because ( in my installation ) you will mount this oil tank inverted. Brass tube Vent / overflow line to top of tank, brass tube strut feed line near bottom of tank.
Meow In order to get oil from the tank we will use a combination of gravity feed and the strut seal to draw oil into the strut. Compress and extend the leg to draw the shock oil into the leg ( think of it as priming the pump ) or " envision a nurse purging air from a hypodermic needle from a vile of medicine etc".
The strut under compression provides a bit of " precharge " to the oil tank once you have pulled oil in and the Tygon line is " prefilled " When the leg extends after take off the extending leg, with the help of the orings will pull oil from the tank and fill approximately 75% of strut with oil.
Upon on landing the compression of the leg will force oil back up the Tygon back to the reservoir. The springs still provide the lions share of the load but the oil helps " even out " any tendency for one leg to re-extend in a xwind or otherwise less than optimum landing.
You out don't need to polish the inner strut but finding the correct oring is a bit of trial and error. Marshall's industrial hardware has a whole aisle worth of them. They will leak a bit so hemostats help mitigate the loss of fluid.
Long winded answer i know know. Hope it makes sense and I will be adding this feature to my next hornet.
Have fun
I tried antifreeze but found it to be too thin then experimented with various viscosity RC car shock oil. I found the 10-15 wt oil to provide the best dampening effect while allowing the springs in the mains to extend the legs fully, thus not interfering with gear doors during retraction. Too viscous and it takes too long to extend too thin and the gear dampening effect is lost.
a 1 oz round Dubro tank plumbed with a 3 line setup and some Tygon tubing is all you need, in addition to the 10-32 tap on the upper strut.
You wIlll need hemostats to clamp off the line when not in use.
Envision a 3 line Dubro stopper in the 1 oz tank configured as such:
fill line ( easily accessible Tygon with plug )
vent line ( brass tube extending straight and all the way to back of tank ) then a Tygon line from the exiting brass tube to an overflow location bottom of fuse
feed line to the upper strut ( this brass tube barely exits stopper inside tank )
Meow you should be holding a standard glow tank with the following exception....the vent line and feed lines are reversed in the traditional sense. The reason I say this is because ( in my installation ) you will mount this oil tank inverted. Brass tube Vent / overflow line to top of tank, brass tube strut feed line near bottom of tank.
Meow In order to get oil from the tank we will use a combination of gravity feed and the strut seal to draw oil into the strut. Compress and extend the leg to draw the shock oil into the leg ( think of it as priming the pump ) or " envision a nurse purging air from a hypodermic needle from a vile of medicine etc".
The strut under compression provides a bit of " precharge " to the oil tank once you have pulled oil in and the Tygon line is " prefilled " When the leg extends after take off the extending leg, with the help of the orings will pull oil from the tank and fill approximately 75% of strut with oil.
Upon on landing the compression of the leg will force oil back up the Tygon back to the reservoir. The springs still provide the lions share of the load but the oil helps " even out " any tendency for one leg to re-extend in a xwind or otherwise less than optimum landing.
You out don't need to polish the inner strut but finding the correct oring is a bit of trial and error. Marshall's industrial hardware has a whole aisle worth of them. They will leak a bit so hemostats help mitigate the loss of fluid.
Long winded answer i know know. Hope it makes sense and I will be adding this feature to my next hornet.
Have fun
05-15-2014, 12:16 AM
#7
Thread Starter
Oh,
I got the reference. Awesome, Buck. You know, it was you who originally turned me onto that flick. Thanks for the explanation. I'm gonna go for it, thanks!
I got the reference. Awesome, Buck. You know, it was you who originally turned me onto that flick. Thanks for the explanation. I'm gonna go for it, thanks!
05-15-2014, 05:57 AM
#10
LOL glad everyone got a chuckle....because it's your dog.....get it? It's your dog??....Oh we got it man!!
It's a very simple mod and the location of the tap on the upper strut cap will be very obvious when you look at optimum locations to drill due to the rotation of the retract etc.
Also, You will want to use two individual 1 oz tanks to feed the respective struts. I tried a single tank on my first jet but discovered the fluid draw between the two legs to be uneven despite exact length tygon lines etc.
I'm looking forward to getting back on this and one other project this summer. The "meow", although fun :-), has taken waaaayyyy too much time away from the garage!!!!
have fun and happy to help.
cheers
It's a very simple mod and the location of the tap on the upper strut cap will be very obvious when you look at optimum locations to drill due to the rotation of the retract etc.
Also, You will want to use two individual 1 oz tanks to feed the respective struts. I tried a single tank on my first jet but discovered the fluid draw between the two legs to be uneven despite exact length tygon lines etc.
I'm looking forward to getting back on this and one other project this summer. The "meow", although fun :-), has taken waaaayyyy too much time away from the garage!!!!
have fun and happy to help.
cheers
