Two or Three, That is the question!
 

So I have been brain storming on this for a while now, Im about to start final setup point on my 1/7 scale F-14 and as you guys no these have heavy gear. I am using robart 2-way valves for the nose and main gear, each valve has two air outs and two air in, with one air supply line. I will run one to the nose gear and plug the second ports, while using both ports running one to each main. My brain storming is about adding a third robart 2-way valve so each gear has its own valve. The only kicker here is which ever setup I go with only have one air supply will be used. What I was wondering is with only one air supply feeding the two or three valves will this defeat my attempt at giving the most air/force to each gear air cylinder, will I be limited on the air leaving the tanks going to each valve? I know this adds extra leak points but all the valves will be run by one servo and the air supply is tied into a gear failsafe. I am about to put the nose on and start so any thoughts would be helpful! Thanks

A note to my madness, I am putting the valves in a location that gives the shortest length of air lines to help and I will be running two large air tanks just for the gear. Cheers
http://www.rcuniverse.com/forum/atta...mentid=2077719

The only way to find out if it'll work is try it. Personally though, i dislike the robart valves for large models, they just dont flow enough air volume ImO.

I agree - but they can be turned down to pass more air - at least up to the point where the nipple size is the limiting factor...

Bob

if you only have one supply in dividing it up is pointless, you are just adding more weight and failure points by adding more valves, add more tanks and increase the line size and pressure if possible.
it is about time some one did a on board compressor for our toys that would be more use than telemetry

The best solution I've found for reliably moving large gear is to use Jet Model Products newer valves. They have the highest volume capability compared to anything else on the market; I've tried them all. Even better is to use their PCU. My latest project has very heavy/large gear like yours. I used Tom Cook's PCU that incorporates the newer valves and manifolds resulting in tremendous improvement over the system that came with the purchase of the jet. Take a look at the JMP website, or even better call Tom and have him explain the product. The valves we've used in the past are just not up to the task required by these heavier gear.

Cheers,
Joe Grice

I think you are looking at the Robart valve wrong. There is one air in. (the single center nipple) That gives you two up outputs (one for the nose gear and one that needs to be T eed for the mains) and two down outputs plumbed the same way…… As far as pressure, the line diameter, length of line, and restrictor setting will not change the pressure to the gear. It will only affect the length of time to get the pressure to the gear.

John no that is how I understand the valve two up two down one air in. As for the other valves people have done some testing on here before and the so high flow valves didn't give true high flow and the larger tubing didn't seem to help. I do remember that thread mentioning a lot about volume being the biggest factor. Someone did mention using one air supply would limit me which is what I have been wondering, I don't care much if the gear moves slower but the force pushing. That being said speed can play a big factor with momentum.Using larger airline isn't a option, I'm sure if you have the tooling you could upgrade the gear to handle larger airline. My thought was having all the air from the valve going to one gear instead of dividing it between two or three gear cylinders. Good stuff so far I will also check out the jump valves the new version that is.

Tank outlet would be the first restriction to eliminate. Then the ID of the line to the valve(s) would be the next to tackle. Any fittings in between could also be a factor. Downstream fittings could also slow things down. But on the cans I have seen out there, the tank outlet is the first restriction. Two tanks (or tank outlets) could cure that. For me, the more air on board the merrier.

I don't think a set of gear are designed properly If it is counting on momentum to retract. If the actuating cylinders are too small then the air pressure needs to be increased. if the air pressure is at its limit then the actuating cylinders need to be larger.

Thanks Todd, Jo I think the gear is designed right I am just looking to get the most bang for the buck. Well since there are plenty of thoughts on this I will start with my two valves and just do some testing for you folks. Then I will switch to three just to so if the gear closes with more force than two. My gear on the Avanti are heavier than the f-14 and have no mechanical advantage, the F-14 has a bit of a arm on the mechanical advantage. The Avanti gear dont closes pretty fast with two of these valves, the nose closes much faster since it has its own valve the mains are slower because the valve is shared. The closing force on the gear is really good there is not rotation on the up/down like the f-14 mains. Good stuff

Keith,

Your F-14 will easily accommodate four of the large air tanks. Use three large plumbed together just for the gear. Use the fourth large tank for doors. Use the two small air tanks for brakes, canopy and speed brake.
The three large tanks plumbed together will give the greatest volume for the gear which will help give at least three clean cycles of the gear. Get out of the way when you flip that gear switch because the cycle will be powerful if you're using the proper valves.

Cheers,
Joe Grice

Fender funny you bring this up. I'm working on my FB F15 now and I've been doing a lot of research on this. A good friend and respected builder told me that he used one large air tank per main with a valve mounted right at the main. Then from there to the sequencer. He said it works perfect. He uses two other tanks for the other gear, doors, and brakes. I've talked to some other people about it and they say it's not necessary but if it works it works. I think I'm going to give it a try on this jet. He's using electronic valves but nothing hi flow and 3 mm line. If anybody else can ring in and give your opinion, I'm all ears. Thanks Scott

More tanks means more volume of stored air, less pressure drop when the gear are cycled = more power to gear. The tanks weigh little if anything and will improve any system.

Bob Neal

I agree 100% Bob.

+ 1

double post

Awesome info, I wanted to make sure when you guys say 3 large tanks we are talking about the same large. These are the 3 tank sizes I have I the Large robart and medium robart, the middle is the skymaster tanks. I understand about volume but it seems like three of the large would be a bit much. I thought about running two of the large and then two of either the skymaster tanks or smaller robart tanks for the brakes/canopy/speed brakes and gear doors. I dont know where I would put four of the large robart tanks but two will under the aft equipment tray just in front of the main full tank, I can put the smaller tanks in the fuse on the outside of the inlets pushed as far forward as possible. I think like some people are stating its all about volume, Aussiebart mentioned his issue was getting the air pushed out on the back side of the air cylinder have more than one valve would deff help this as well.... I will post some findings and do a few videos showing the setups and how they work when I get to the final setup, I have the gear out at the moment doing other things.

http://www.rcuniverse.com/forum/atta...mentid=2077913

Here is a video of my 1/4 scale Panther gear on 1 large Robart tank with 100 PSI in it. I used the same valve you showed in the first post https://www.youtube.com/watch?v=6INtZeAOYfA