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try uniflow setup..!
Hej Tore, fler skandinaver i farten på denna sajt.....kul..!
switch to english now to be polite - You could consider trying the so-called uniflow setup which will minimize airborne gadgets as Jan rightly puts it - just one more clunk and that´s it. Tried it myself recently on a sidemounted Saito 56 and it sure does work - in fact it is an old CL invention which is worth considering while waiting for the pump. Please check the following thread http://www.rcuniverse.com/showthread...37#post1344426 lycke till Tore......hej då..../Haraldd |
RE: try uniflow setup..!
OK, here is my problem... I am running an OS 70FS and need to run a VP-20 because of the level of my tank.
The engine runs well with the high speed needle set at about 1 1/2 turns open. I connected the VP-20 and set it open about 5/6 of a turn from fully closed. At this setting I had to close the needle to 1 turn open to run well. I assumed that the pump was pumpoing way to much fuel so I closed the pump about 1/6 of a turn and returned the needle valve to where it was pre-pump. The engine would sputter and die after I removed the glow plug battery. Any Help would be great! This is my first FS My Goal is to get the Perry working.. not spend more on a regulator Thanks Nate |
RE: try uniflow setup..!
Hi!
What strange plane do you have that doesn't allow you to have proper engine/tank combination?? Can you show us some pictures please? |
RE: Perry oscillating pump?
ORIGINAL: sandal Does this mean that I can set the needle near peak with the fuel tank full, and leave the needle in that position for the entire flight? IF, IF, IF. Then yes. If your VP-20 tank is in great condition, then yes. If your fuel tank isn't ridiculously far behind your engine. Yes. If your fuel tank isn't ridiculously lower or higher than your engine. Yes. If your engine's air seals are all up to snuff. Yes. If your fuel is right for the engine. Yes. If you are using the correct prop. Yes. If you are using the correct glow plug. Yes. Then why am I making a big deal out of this? Because if one thing is out just a tiny bit, you'll be raving and ranting about the cheap, low quality, P.O.S. that the VP-20 Oscillating Pump truly is. Seriously, this is a great pump, but there are limits to what it can and cannot do. Ed Cregger |
RE: try uniflow setup..!
Why does everyone instantly ask what kind of wacko airplane you have when you ask about setting up this pump? It cracks me up...
Can someone with experience with the VP-20 please help, that's all I ask? and to everyone here.. Happy New Year and Happy Landings :) Nate |
RE: try uniflow setup..!
ORIGINAL: OSUAV8R OK, here is my problem... I am running an OS 70FS and need to run a VP-20 because of the level of my tank. The engine runs well with the high speed needle set at about 1 1/2 turns open. I connected the VP-20 and set it open about 5/6 of a turn from fully closed. At this setting I had to close the needle to 1 turn open to run well. I assumed that the pump was pumpoing way to much fuel so I closed the pump about 1/6 of a turn and returned the needle valve to where it was pre-pump. The engine would sputter and die after I removed the glow plug battery. Any Help would be great! This is my first FS My Goal is to get the Perry working.. not spend more on a regulator Thanks Nate |
RE: try uniflow setup..!
1 Attachment(s)
Hi!
Why I ask is because if you mount your engine in a correct way you don't need a pump. A pump always means trouble! I haven't seen a plane that could not have the tank mounted correctly= tight against the firewall. Al it takes is a bit of modification to the fuselage...or use Tettra "Bubbless tank...or that you sweat solder your own tank. Here is the 110cc tank I made from 0.3mm tin plate for my Marutaka DC-3. Second picture is the 150cc Tettra tank in my Q-500 Viper. |
RE: try uniflow setup..!
OK, I've been trying to just watch this thread and not get involved, ain't working. For one, not all installations allow for the engine to be mounted in just any position. Remember some planes have cowls and such that the OP might not want to cut up. Some airplanes won't work with any tank position except the stock one, unless you are willing to do extensive modifications. In some applications the flyer might want his tank in a particular location to allow for a certain type of flying to work better. I am referring to 3D in this instance and the tank in my AeroWorks Extra 260 is back on the CG which leaves a long way for my 91 Saito to pull fuel while in a hover and the throttle is being pumped in order to maintain control. Frankly it won't do it; I have to run a pump. In my case I chose a VP-20 and after some considerable effort finally got it adjusted and wouldn't go back to unpumped for all the tea in....well we all know how that story ends. My point is with my tank some 10 to 11" behind the carb fuel draw was marginal when trying to hover so I went the pump route. Yes I could have moved the tank right up behind the engine and it would have ran OK, I know this because I have owned this particular engine for over ten years and it has been on numerous planes. It ran great on all of them. I now have the desire, which I understand some folks wouldn't agree with because it's not their idea of flying, to master the art of 3D. The smaller birds just work out better with the tank back on the CG mainly because the CG is set up right on the neutral point and the fuel burn would cause it to move too far aft making the plane harder to control.
Now that we have established that there are legitimate needs to have fuel tanks in unusual locations and that engines must sometimes be mounted a certain way the next thing we need is help getting the OP set up with his pump. On mine, I set the needles without the pump and then hooked up the pump up. My engine was running just a little too rich at that point and would die when throttled up so I started turning the hex inward lowering the volume on the pump until the tune was good again on the high side. In my particular case I had to lean the low end just a tad at this point. I can now fly an entire tank without the mixture changing any noticeable amount and can hover for the full tank if desired. That's with the tank a full ten to eleven inches lower than my engine while in the hovering attitude. It takes some effort to get everything set up right with a pump but IMHO and at least in my case it is worth every minute of it. For the OP, don't give up, the VP-20 can be made to work nicely on a four stoke. |
RE: try uniflow setup..!
1 Attachment(s)
Hi!
Why have the tank on the C of G in such a small glow model? It flies and hovers just as good with the tank just behind the firewall! In my Yak-50 (gas) where I use a gas engine with walbro pump I don't have to think about where I put the tank, in that case the tank can be put on the C of G without any trouble. But in 99% of all glow engined powered models the tank could be mounted just behind the firewall without too much trouble. Here is a second example on how an plane can be slightly modified to have the engine comply with the tank rule. The Great planes You-Can-do.60 with the engine mounted on it's side instead of inverted. ...I'm still curious to see what the engine /tank installation looks like...Please! |
RE: try uniflow setup..!
It's nice to know we can all still have our opinions Jan. I find the CG change from fuel burn to be noticeable and unacceptable if the tank is all the way up front. 16oz of fuel is about 3/4 of a lb. IMHO, that is a bunch of weight change on a 6lb model. I also find it much easier to install a Perry Pump with just two screws as opposed to modifying my airframe and cowling. The adjustment of the Perry pump took less than 30 mins (I admit I didn't time it but it wasn't very long) and I haven't had to touch it again. The OP wants help getting his pump adjusted correctly and I am not going to try and change his mind. I am sure he has his reasons for wanting to do it the way he is doing it, maybe he just wants to learn how a pump works. It's important to try different ways of doing things; one size doesn't always fit all.
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RE: try uniflow setup..!
ORIGINAL: OSUAV8R Why does everyone instantly ask what kind of wacko airplane you have when you ask about setting up this pump? It cracks me up... Can someone with experience with the VP-20 please help, that's all I ask? and to everyone here.. Happy New Year and Happy Landings :) Nate Because in the real world of physics, there are no magical pumps that work exactly the same from one set of circumstances to another. And, with you being a fellow modeler, we would like to give you the most accurate and easy answer as possible. Ed Cregger |
RE: try uniflow setup..!
That's pretty good Ed. Maybe one thing to add to the magical pumps part is that these pumps are adjusted on volume not pressure and since every engine uses a different amount of fuel there is no "magical setting" or one size fits all approach. Setting the high needle before hooking the pump up and then turning the hex inward after hooking it up until it ran perfect without moving the high speed needle is what I did and it didn't take long either. I just left the glow plug hooked up (I use a power panel anyway so no batteries to worry about) and I would start it, shut it off adjust and start it again until I got it right. After getting the high end running good I had to lean the low end but can't remember how much exactly. It wasn't much though. It was pretty good when I throttled back after getting the high end right so not much was needed there.
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RE: try uniflow setup..!
Ed,
I understand your point... but it just sounds like people are calling you (i,e, me) and idiot for not being able to get your tank to the right level. Anyway.... I have set my HS needle without the pump .. and and am slowly closing the hex on the pump. as of right now the engine runs but throttle response is awful. If I throttle back and then throttle up the engine RPM lags very badly and will only shoot up if I momentarily pinch the fuel line So I assume the pump is pumping way to much.. so the process continues Nate |
RE: try uniflow setup..!
Hi!
Just want to help! [:o] ...Still curious how your plane and tank set-up looks like! |
RE: try uniflow setup..!
Jaka,
It is a normal set up.. side mounted os-70 fs and tank right behind. I cant get the tank to the correct level due to the bulkhead, and without a pump the mixture changes as the tank empties.. The pump will give me outstanding consistency .. exactly why the engines now come with a pump attached I will keep you all posted :) |
RE: try uniflow setup..!
One more quick question.. and it may be the root cause of my problem... I left the muffler pressure connected after I plugged the pump in... will this affect the pump/mixture setting?
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RE: try uniflow setup..!
Yes it does affect it. I don't run any muffler pressure but have seen several guys with theirs set up that way and it seem to work great. I just never have used mine that way.
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RE: try uniflow setup..!
ORIGINAL: Jezmo OK, I've been trying to just watch this thread and not get involved, ain't working. For one, not all installations allow for the engine to be mounted in just any position. Remember some planes have cowls and such that the OP might not want to cut up. Some airplanes won't work with any tank position except the stock one, unless you are willing to do extensive modifications. In some applications the flyer might want his tank in a particular location to allow for a certain type of flying to work better. I am referring to 3D in this instance and the tank in my AeroWorks Extra 260 is back on the CG which leaves a long way for my 91 Saito to pull fuel while in a hover and the throttle is being pumped in order to maintain control. Frankly it won't do it; I have to run a pump. In my case I chose a VP-20 and after some considerable effort finally got it adjusted and wouldn't go back to unpumped for all the tea in....well we all know how that story ends. My point is with my tank some 10 to 11'' behind the carb fuel draw was marginal when trying to hover so I went the pump route. Yes I could have moved the tank right up behind the engine and it would have ran OK, I know this because I have owned this particular engine for over ten years and it has been on numerous planes. It ran great on all of them. I now have the desire, which I understand some folks wouldn't agree with because it's not their idea of flying, to master the art of 3D. The smaller birds just work out better with the tank back on the CG mainly because the CG is set up right on the neutral point and the fuel burn would cause it to move too far aft making the plane harder to control. Now that we have established that there are legitimate needs to have fuel tanks in unusual locations and that engines must sometimes be mounted a certain way the next thing we need is help getting the OP set up with his pump. On mine, I set the needles without the pump and then hooked up the pump up. My engine was running just a little too rich at that point and would die when throttled up so I started turning the hex inward lowering the volume on the pump until the tune was good again on the high side. In my particular case I had to lean the low end just a tad at this point. I can now fly an entire tank without the mixture changing any noticeable amount and can hover for the full tank if desired. That's with the tank a full ten to eleven inches lower than my engine while in the hovering attitude. It takes some effort to get everything set up right with a pump but IMHO and at least in my case it is worth every minute of it. For the OP, don't give up, the VP-20 can be made to work nicely on a four stoke. I just reread your response. Do you think that "we" haven't tried and flew exactly the same models that you have described in your list of oddball airplanes? Who do you think invented this stuff? We are in deep trouble when the hobby becomes populated by people who think that anything technical is boring or stupid. Or that the people that are technically oriented should be ridiculed when they answer a question accurately and sincerely. Ed Cregger |
RE: try uniflow setup..!
I had one set that way and it worked, but the pump crapped out in a year or so. I asked about it and was told that even when it worked it was hard on the pumps dipragram and check valves.
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RE: try uniflow setup..!
ORIGINAL: NM2K ORIGINAL: Jezmo OK, .........it. For the OP, don't give up, the VP-20 can be made to work nicely on a four stoke. I just reread your response. Do you think that ''we'' haven't tried and flew exactly the same models that you have described in your list of oddball airplanes? Who do you think invented this stuff? We are in deep trouble when the hobby becomes populated by people who think that anything technical is boring or stupid. Or that the people that are technically oriented should be ridiculed when they answer a question accurately and sincerely. Ed Cregger |
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