stunthanger.com
Engine basics => Engine set up tips => Topic started by: Rudy Taube on November 03, 2007, 07:45:13 PM
-
Hi Engine guys,
I am finally getting around to breaking in my AeroTiger that is going into my Nobler.
My ?s are:
1.The NV is on the Muffler side. My OS engines also have the NV on the Muffler side. Is there any good reason for this? Or do they just like to test our skin toughness? :X
2. I removed the spray bar and put it on the opposite side (NV now away from the muffler). Is this OK? ... Or will this destroy the universe like flipping the Tralfamadore Switch? ~^
BTW: I did mark the spray bar, and Venturi, so that the small hole is in the same place.
TIA for your help.
-
I don't qualify myself as an expert, but I always (if I can) out the needle opposite the muffler, because like you point out, I don't like getting burned by the muffler. I don't see any issues.
-
Just my 2cent's if your flying counterclockwise, where is the fuel going to, the outside of the tank, where is the fuel pick up, the outside of the tank, can you route the fuel line to the inside? I guess you could, never tried it.
Walter
-
I always move mine to the side opposite of the muffler, and route the fuel tubing around. I have noticed no difference.
-
There is no difference on which side NVA is mounted. What matters is where fuel pickup is. for example, if the motor is mounted inverted, fuel tank fuel line is on the outside wall side. Therefore, NVA pickup has to be mounted pointing towards the outside. In a side mounted configuration(profiles) it does not matter but what matters is convinience. It's a lot more convinient to have the needle pointing up than down.
-
Rudy,
I didnt think that electrics had needle valves?
LL~
-
Thanks guys for all your answers.
It looks like having my inverted engine with the NV on the opposite side from the muffler will not be a problem. Good news for my fingers! #^
Good one MARK! ~> I just thought I would try to keep within the "spirit" of classic and have my classic BOM legal Nobler powered with a "slimer". And I really like the smell of Nitro/Castor oil in the morning! .... My PA and P-40 planes are still all E powered. y1
BTW: speaking of Nitro. I went to the NHRA National Championships at Pomona this weekend. ..... 85% Nitro = WOW!!!! .... It had been about 30 years since my last drag race, I had no idea that they have gone from 2,000 HP to over 6,000 HP in that time period. LOUD!!!!!! The earth moved (my friend said they measured it at 2.3 on the Richter scale). 4.5 seconds for 1/4 mile at 333 MPH is just obscene! (and that was a guy who LOST!) But it sure was FUN!!!!! :-)
Thanks again guys for your help.
Regards, H^^
-
Rudy? ??? Alan? ???
Building SLIMERS with the NV on the WRONG side???? ~^
I dunno, maybe that Trafaldamor switch thingy has already been thrown! :X ;D LL~
-
Essentially, as far as the fuel system itself is concerned, it makes almost no difference which side of the engine the needle valve is located. Let me explain why this statement has so many qualifications to it.
For a conventional inverted or upright mounted engine and for a "typical" installation where the pickup tube in the tank is essentially at the same level as the spraybar or the fuel exit into the venturi and consider circular flight where there is a pressure head where the fuel pickup tube is located.
Draw pressure or force diagrams that represent the fuel in the tubing from the the pickup point in the tank to the hole in the spray bar in the venturi. Do this for the case where the needle valve is on the opposite side of the engine from where the fuel pickup tube collects the fuel inside the tank, as in a "typical" wedge tank. This configuration will normally allow the shortest path through the tubing from the pickup point to the spraybar hole.
Now, draw a similar diagram where the needle valve is on the same side of the engine as is the pickup tube in the tank. This configuration will normally require an additional amount of fuel tubing around the crankcase to get to that hole in the spraybar. The pressure head or the difference in the lateral distance from where the fuel enters the pickup tube and the hole in the spraybar is the same. The only difference is that in the one case, the fuel must travel through a bit more tubing, so there is a slight pressure difference because the fuel must travel through a longer piece of fuel line. This pressure difference is probably negligible, at least as far as making any difference on which side of the engine where the needle valve is located. However, if one feels that it is important to keep the fuel line length to a minimum to reduce pressure differential at the ends of that fuel line, then the needle valve should be on the engine opposite where the fuel pick up tube is in the tank. Or another excuse to put the needle valve on the engine opposite of the fuel pickup tube is in the tank will normally allow a "neater" fuel line installation in the nose of the model to avoid the need for the fuel line to wrap around the crankcase of the engine to get to the other side. However, this fuel line wrapped around the crankcase situation can be avoided by simply routing the fuel pickup tube inside the tank to go from the wedge to the opposite side of the tank before it exits the tank, thereby shortening somewhat the total length of the fuel line, albeit still longer than if the needle valve is on the opposite side of where the fuel pickup is. That pickup tube does not have to be straight. The only thing that is really important here is where the end of that pickup tube is to gather the fuel to go to the engine.
Once this is understood, then similar diagrams can be produced for clunk tanks and/or for side mounted engines and/or any combination of all of the above and the same conclusion can be drawn. You can mount the needle valve on either side of the engine. However, if you think it is important to minimize the distance the fuel must travel from the pickup to the venturi, and there are some who think this is an important parameter, then that requirement starts to dictate which side of the engine to mount the needle valve, burnt fingers and/or NV protection notwithstanding.
Keith Trostle
-
Hi Engine guys,
I am finally getting around to breaking in my AeroTiger that is going into my Nobler.
My ?s are:
1.The NV is on the Muffler side. My OS engines also have the NV on the Muffler side. Is there any good reason for this? Or do they just like to test our skin toughness? :X
2. I removed the spray bar and put it on the opposite side (NV now away from the muffler). Is this OK? ... Or will this destroy the universe like flipping the Tralfamadore Switch? ~^
BTW: I did mark the spray bar, and Venturi, so that the small hole is in the same place.
TIA for your help.
HI Rudy
You will get various answers on this, My experience has not been all that good with doing this. I had a ST 46 powered StuntCraft that I moved the NVA around to the opposite side. The engine run got worse, It broke harder and wound up on maneuvers. I switched back and it instantly went back to the normal run.
I have tried this several times on several differant airplanes, unfortunate but all my results were not as good as others. Some only had a small amount worse run, some had a terrible run.
I switched sides with my 1989 APEX design in about 92 or so, this was the plane I flew at the NATS in 89 or 90. It changed the run slightly the motor would cycle slower with the NVA on the opposite side. I switched back to the muffler side and the run went back to normal. I then made a NVA that had the pickup and Needle on the same side and installed it. It worked perfectly the run was exactly the same. Now depending on if this was caused from a longer fuel tubing or the bend around to the other side of the motor..or whatever caused it, I would advise you to try it both ways to see for your self.
I suspect that engines that have a very good fuel draw will be non -affected , and ones that have a lower fuel draw may have more troubles
Regards
Randy