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Model Forum / Radio Controlled / Air Models / October 2008fuel tank size
i'm planing to use os 120 engine on a new model and want to use a big fuel tank in order to get a long flight time (about 1000 cc). I read in the past that there is a limited size for the tank, and you cant use a big size tank. in the manual of the engine the recomended size is about 350cc. is it a problem to use bigger tank? and if yes is there a way to do it? dan >is it a problem to use bigger tank? I have a Telemaster with an OS 1.08 and a 1000cc tank. No problems whatsoever. The Telemaster can carry a lot of payload and is not very sensitive to CG location, so the weight is not a problem either. If I fly a lot at full power, such as when lifting gliders, I get about half an hour on a tankful.  SignatureRoRo >i'm planing to use os 120 engine on a new model and want to use a big >fuel tank in order to get a long flight time (about 1000 cc). [quoted text clipped - 3 lines] >is it a problem to use bigger tank? >and if yes is there a way to do it? In my view, the best thing to do is to just try the tank size you want and see what happens. The issue is probably fuel draw. You will also have a very large shift of CG as you drain the tank if you locate it off the CG of the plane. If the tank is forward, the plane will be nose-heavy at takeoff less so when the tank is empty. You can get various pumps or fuel regulators to help with the draw. I've heard good things about Perry pumps and Kline regulators but haven't used either myself. Another potential problem: inconsistency during the run. The big tank may produce extra pressure when full. I usually try to get the centerline of my tanks at or just below the position of the spraybar in the carb. With an oversize tank, you may have to run overly rich at first in order not to run too lean later in the flight. My guess is that you can probably solve all these problems ... Good luck with your project. Let us know how it turns out. Marty SignatureBig-8 newsgroups: humanities.*, misc.*, news.*, rec.*, sci.*, soc.*, talk.* See http://www.big-8.org for info on how to add or remove newsgroups. >>i'm planing to use os 120 engine on a new model and want to use a big >>fuel tank in order to get a long flight time (about 1000 cc). [quoted text clipped - 35 lines] > > Marty --------------- As Marty has indicated, the fuel pressure head will vary during your flight and change your mixture as the engine consumes the fuel. This is not good because as the fuel is burned off, the fuel to air ratio seen by your engine becomes leaner and leaner. There are three solutions to this problem. The first is to buy an engine with a pressurized fuel system installed by the factory, such as a YS or an OS FS-120 Surpass III/Pump. The second solution is to buy a third party pump/regulator such as the Perry system. The Perry system is a pump that relies upon crankcase impulse pressure gained from the engine's lower crankcase area (two-stroke). This can also be made to work with a four-stroke if you look for the information here on RCU. The third option is to go with a Cline Regulator. The Cline Regulator requires that the tank be pressurized over atmospheric level. This is easily accomplished by running a pressure line from the muffler to the fuel tank vent line. This choice is my favorite of the three. It is the simplest. It is effective. It is relatively inexpensive to accomplish ($60 USD, plus shipping) and it works with no known disadvantages when compared to the other two methods. With all three of the choices listed above, it is feasible to mount the fuel tank near the balance point of the model (CG), so as not to suffer a severe trim change as the fuel burns off. Good luck. Ed Cregger | >>i'm planing to use os 120 engine on a new model and want to use a big | >>fuel tank in order to get a long flight time (about 1000 cc). [quoted text clipped - 67 lines] | | Ed Cregger Excuse me for breaking in here but there are more options. Varsane (Perry) makes a vibration operated pump that they recommend for 4 strokes. Here is a Saito link that covers the options for their engines which would apply for other non pumped engines as well. http://saito-engines.info/pumps.html I have used the VP-30 (red body) for mounting the tank over 6 inches behind the engine on an OS BGX3500 with good results and used them with Fox engines routinely because of fuel draw problems due to their large venturi opening. SignatureAnyolmouse > | > On Tue, 21 Oct 2008 07:49:17 -0700 (PDT), dan <danim...@gmail.com> > wrote [quoted text clipped - 101 lines] > -- > Anyolmouse Tnx for the information after reading in the internet about the Cline Regulator iunderstood that using it with 2 cycle engines means to get pressure from the cranck case. is it correct? can i use the regukar pressure from the muffler?? >Tnx for the information >after reading in the internet about the Cline Regulator iunderstood >that using it with 2 cycle engines means to get pressure from the >cranck case. is it correct? >can i use the regukar pressure from the muffler?? According to the Cline website, they recommend crankcase pressure for 2-cycles and muffler pressure for 4-cycles: http://www.billsroom.com/pcfs/products/CFS/pcfs_install.htm Marty SignatureBig-8 newsgroups: humanities.*, misc.*, news.*, rec.*, sci.*, soc.*, talk.* See http://www.big-8.org for info on how to add or remove newsgroups. On Oct 24, 9:07 pm, "Anyolmouse" <Anyolmo...@invalid.invalid> wrote: > "Ed Cregger" <ecreg...@bellsouff.net> wrote in message > [quoted text clipped - 3 lines] > wrote > | > in <94b53f65-6e23-4597-8616-33a5cd354...@d31g2000hsg.googlegroups.com>: > | >>i'm planing to use os 120 engine on a new model and want to use a > big [quoted text clipped - 96 lines] > -- > Anyolmouse Tnx for the information after reading in the internet about the Cline Regulator iunderstood that using it with 2 cycle engines means to get pressure from the cranck case. is it correct? can i use the regukar pressure from the muffler?? You pressure your tank with crankcase pressure when using it on a 2 cycle engine and you must use exhaust pressure when you use it on a 4 cycle engine. The Cline is a REGULATOR. It is not a pump. It uses a check valve to hold pressure in the tank and then it regulates a constant pressure to the engines needle valve. Did you follow the link to Cline? http://www.billsroom.com/pcfs/products/CFS/fuelsysdesc.htm The instructions are here: http://www.billsroom.com/pcfs/products/CFS/pcfs_install.htm If you click on the box marked schematic for one tank-one engine that is on the right side of the screen it will show you exactly how to hook it up. The tees shown for venting and filling MUST be stopped up after filling the tank for the system to work properly. A minus for the Cline system is that the system is pressurized at least 2lb/sq in which requires very secure fuel line connections. Some of the guys I knew that were using the system wrapped their tanks with nylon stranded packing tape to control tank expansion. All of the above is why I decided to use the Perry pump system. It will draw fuel up to 9 inches away from the pump using crankcase pressure only. While I haven't tried it, others have used exhaust pressure in conjunction with the pump for greater pump to tank distances. SignatureAnyolmouse >Did you follow the link to Cline? >http://www.billsroom.com/pcfs/products/CFS/fuelsysdesc.htm >The >instructions are here: >http://www.billsroom.com/pcfs/products/CFS/pcfs_install.htm >If you click >on the box marked schematic for one tank-one engine that is on the right >side of the screen it will show you exactly how to hook it up. The tees >shown for venting and filling MUST be stopped up after filling the tank >for the system to work properly. >A minus for the Cline system is that the system is pressurized at least >2lb/sq in which requires very secure fuel line connections. Some of the >guys I knew that were using the system wrapped their tanks with nylon >stranded packing tape to control tank expansion. I think the pattern guys often do that when setting up YS systems, too. The trouble with expansion is that a tank can split along the seams after it's gone through enough cycles. >All of the above is why I decided to use the Perry pump system. It will >draw fuel up to 9 inches away from the pump using crankcase pressure >only. While I haven't tried it, others have used exhaust pressure in >conjunction with the pump for greater pump to tank distances. Marty SignatureBig-8 newsgroups: humanities.*, misc.*, news.*, rec.*, sci.*, soc.*, talk.* See http://www.big-8.org for info on how to add or remove newsgroups. > On Oct 24, 9:07 pm, "Anyolmouse" <Anyolmo...@invalid.invalid> wrote:> "Ed Cregger" <ecreg...@bellsouff.net> wrote in message > [quoted text clipped - 150 lines] > > - Show quoted text - Tnx for all the answers and to marty, I'm an expirienced rc builder and flyer, but still things that i don't know i prefer to ask, and ask again, instead of doing things wrang dani > > On Tue, 21 Oct 2008 07:49:17 -0700 (PDT), dan <danim...@gmail.com> wrote > > in [quoted text clipped - 73 lines] > > - Show quoted text - Tnx for the information about the cline regulator..... i'm going to use a 2 cycle engine, from the article i read in the internet in 2 cycle engines the pressure comes from the cranck case, that to my understanding means to drill a hole in the engins case. can i connect the pressure to the mufller's regular pressure conection? while using the cline reg with 2 cycle engine? Tnx >about the cline regulator..... >i'm going to use a 2 cycle engine, >from the article i read in the internet in 2 cycle engines the >pressure comes from the cranck case, that to my understanding means to >drill a hole in the engins case. can i connect the pressure to the >mufller's regular pressure conection? while using the cline reg with 2 >cycle engine? The Cline system requires no drilling. All of the contemporary 2-cycle designs get pressure from the muffler-tap. I haven't heard of any tapless muffler in years and years. The Cline system gets pressure from the muffler tap and keeps the pressure high in the tank by the use of a check valve (that may be the weak link in the Cline system). Then the regulator is placed in the fuel line near the needle valve (within 1" or so, if I remember correctly). When the regulator "feels" suction from the fuel line, it lets a dose of fuel through; when the suction stops, so does the flow of fuel. Some of the pumps do get pressure from drilling holes in the crankcase. Those are different from the Cline system. It sounds as though you haven't done any RC yet. You might want to go with a smaller, simpler rig until you get up to speed on how things work. Marty SignatureBig-8 newsgroups: humanities.*, misc.*, news.*, rec.*, sci.*, soc.*, talk.* See http://www.big-8.org for info on how to add or remove newsgroups. |
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