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Patriot/YS45 pipe setup

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Old 09-20-2004, 10:12 PM
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HavinFun
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Default Patriot/YS45 pipe setup

This being my first tuned pipe I guess there is a learning curve to these things. I read the setup tips on the Macs, Jett websites & here on RC Universe. At the field I first ran it open faced, APC 9x8, PowerMaster YS 20/20 fuel,OS A3 plug. Got 16100 rpms. I bought this engine used with a header which has been cut, do'nt know which pipe was used before, the header now is 4 3/4 inches long. put the header & pipe on with about 1/2 inch separating them in the coupler. It peaked out at about 16600 & I backed the NV down to 16000, I thought it was running great so I shut the engine down & let her cool a bit before refueling. Refueled & started again to do a radio check, throttled up to about 8000 rpms for about 2 minutes while I did the radio check, radio checked out fine so as I was walking back I throttled down to idle & she just quit. I was still about 100 feet away, When I got to the plane the engine was very hot. Now I was baffled, would run fine at WOT but at midrange would over heat! Today I reset the regulator, turned it out about 1/4 turn to richen the low end & readjusted the pipe/header so now there is a 1/8 inch gap between them in the coupler, Ran it up & peaked at 17100, set NV at 16300 now she runs about the same temp at idle,midrange, & WOT. She seems to be loading up a bit on extended idles, will try leaning the regulator a bit & hope it does'nt run hot again. With the pipe setup this way it seems to come on the pipe at about 9000 rpm, anything between 9000 to 1100 rpm runs kind of ragged jumping on & off the pipe. Compared to my other 2 stroke engines running the stock mufflers this YS 45 runs a bit hotter, is this normal? Does the pipe setup/rpm sound about right? Should pipe be shortened/lengthened? Any comments please... []
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Old 09-21-2004, 10:28 AM
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Razor-RCU
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Default RE: Patriot/YS45 pipe setup

I have never used a tmp. gauge on these engines so I am not sure about that part...

As to the pipe- Shortened! Sounds like less gap is the right way to go, most recommend cutting the header until the RPM's do NOT increase and stopping there- try a search on here for tuned pipe tuning or similar and grab a cup of coffee!

I rarely run my performance engines (Anything other than idle-) for very long on the ground since there is no cooling while it is sitting still- that sounds like the problem right there...

You might also try a 10x7, my brother is using the same combo you are so I will get back to you when he flies- He is runnin 9x8 apc and I also told him to try a 10x7
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Old 09-21-2004, 10:56 AM
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Default RE: Patriot/YS45 pipe setup

One of the issues with full size pipes, is there is always an RPM band where the engine will not enjoy running. Usually this can be minimized.

What pipe length are you running (plug to high-point of pipe) ?

There is no specific reasion the YS45 would run hot, other than being lean. If the pipe is set too short for the prop you are using (rpm), and the engine is struggling to stage or stay up on the pipe...... it will tend to run hot (basically is a lean condition). A temp gauge will not tell you much about how the engine is performing... but its pretty obvoios if the engine is getting overheated just by looking and listening.

A tuned pipe pretty much defines the RPM the engine will operate at. If you have it tuned for, say, 16K rpm, you have to select a prop that will easily let it achieve that rpm (or just short of it) on the ground.

A pipe that is set up too long will have issues as well. The engine will reach the tuned point too early, and cause some very goofy midrange problems as the engine trys to stage up onto the pipe while its only at about 1/2 power. It will load up in transition both throttling up, and throttling down.

It almost sounds like you have the pipe set too long for the prop you are turning.

From your RPM quote on the 9x8, you are not too far off... but it doesn't take much to make a difference. Easy way to test this...... keep the pipe the same length, and then add more prop. Try going to a 10x6, and then a 10x7. If the engine struggles just a bit to come on the pipe on the ground, you have found the right prop for the pipe length.

If you want to go back to the 9x8, shorten the pipe installation up a bit (1/4" or so) from where it ran well with the 10x7.

Of note, when you install a pipe/header installation.... keep the gap between them as SMALL as possible. Never more than 1/8". Anything much more than that, and you will end up replacing couplers quite often (it gets VERY hot at that junction) and you may see some odd engine performance issues is the pipe bounces around too much.

Bob
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Old 09-21-2004, 06:16 PM
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HavinFun
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Default RE: Patriot/YS45 pipe setup

Thanks for the replies guys. I flew her today & she handled great but I think further tuning of the pipe may be in order. After the first flight when coming in for a landing I throttled down to idle & she quit, I thought I might have the idle set too low but it turned out to be a burned out glow plug. Replaced it with another OS A3 plug & bumped up the idle a couple of clicks & put another 3 flights on her with no problems. The pipe length now is 10 3/4 inches from plug to start of high point on Macs # 1140 7.5cc pipe. At what rpm should it start to come on the pipe? Right now it comes on the pipe at 9000 rpm. Will try the other props, have some apc 10x6 & 10x7. How do you think an apc 9x9 would perform here? All my take offs & landings today were off grass, we do have a paved 200 FT runway but with a 10 mph crosswind today I just kept her on the grass & pointed her into the wind. Took about 200 feet before she built enough speed for take off. Once airborne & trimmed she was hauling ... Make a loop as big as I wanted, she had to be doing 100+ mph. Landings were all a little hot mainly because I would keep the throttle at about 1/4 till just before touch down for fear of killing the engine if I let her idle too long. Was using the flaps on landings, will have to deflect them a bit more & come off the throttle earlier to slow her down more. But overall I'm happy with the first flights & now that I've seen what this setup is capable of, I will try different prop/pipe setups to try to improve on this.
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Old 09-21-2004, 07:01 PM
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Razor-RCU
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Default RE: Patriot/YS45 pipe setup

Great pics- You may need to mix in some down elev. when flaps are deployed to keep from "ballooning"-

The 9x9 will give better top speed but lengthen the takeoff roll- My Jett-50 was best w/ 9x9 not sure about the YS-

I would try a 10x7 maybe even 10x8-
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Old 09-22-2004, 12:04 AM
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Default RE: Patriot/YS45 pipe setup

I do have down elevator mixed in with the flaps. Right now I have the flaps droping about 1/4 inch & the elevator about 1/8 inch or less. She does balloon a little bit when first deployed but will start to sink as speed is scrubbed off. Will try the 10x7 & 10x8 props, would'nt mind shortening the takeoff roll but I'd like to keep the top speed or even increasing it a bit.
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Old 09-22-2004, 08:21 AM
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Default RE: Patriot/YS45 pipe setup

Razor has a bit more experience with the YS and pipe set up. But it seems to me that length may be a bit short for the application. Let me check my notes.

The last YS.45 SE I set up have worked with had a jett-stream muffler installed... was no tuning involved.
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Old 09-22-2004, 09:52 AM
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Default RE: Patriot/YS45 pipe setup

Ok, I was able to find some old notes I had...... was for another engine, slightly differnt pipe...but should be applicable for the YS 45 (or at least close)

(but as noted, if others have specific YS info, please..... use theirs)

For the rear exhaust setup.... 17,000 rpm peak target...... length was 8.5"
For the side exhaust setup .... 17,000 rpm peak target...... length was 11.75"

length measure from plug, along centerline of header and pipe to the end of the divergent section of the pipe (fat part).

A 9x8 or 10x6 should run easily at that 17K target. A 9x9 or 10x7 might make it there too if the engine is running well. Again, you ideally want your ground RPM approaching, but not passing the tuned point. The engine will unload to full power once in the air.

I also had a note here where I had run an APC 11x7 on the YS45 at 310mm (12.25") which should be somewhere around 15,000 rpm.

From your numbers, and from looking at the photos....you may have the pipe set too short actually.

You noted that it staged at around 9000 rpm. That makes sense... let me explain.

Just doing a few quick calculations, 18K rpm would tune down closer to 11.25" long. At 10.75", I estimate that the tuned rpm would be somewhere closer to 19K rpm. So what you are seeing, is the pipe staging on a harmonic of its tuned length (about half wave, or half of 19,000 or 9500 rpm). If this is the case, the pipe is likely really helping a small bit on the top end.... bit is working more like a "good" muffler since it can not approach its true tuned point. Since it is currently running around 16.5K rpm ground peak, and is likely unloading a bit to around 17.0-17.5K in the air, it may be in a really bad spot of the 'wave'. A engine struggling to come up on the pipe will cause basically a lean condition and very poor transition. That could have caused your blown plug.

Again, there are some others here who may have specific YS45 and pipe information. If their info is different than what I have here, definately go with their first hand info.

Bob
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Old 09-22-2004, 04:06 PM
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Default RE: Patriot/YS45 pipe setup

"Of note, when you install a pipe/header installation.... keep the gap between them as SMALL as possible. Never more than 1/8". Anything much more than that, and you will end up replacing couplers quite often (it gets VERY hot at that junction) and you may see some odd engine performance issues is the pipe bounces around too much.

Bob"


So if my header/pipe is too short now how can I increase the lenght without buying a new header? []
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Old 09-22-2004, 04:26 PM
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Default RE: Patriot/YS45 pipe setup



ORIGINAL: HavinFun

...would'nt mind shortening the takeoff roll but I'd like to keep the top speed or even increasing it a bit.
Just slap on the APC 9*9 prop and let it rev. Your pipe length of 10 3/4 inches sounds fine for the 9*9 prop. The engine should jump on the pipe real bad during a dive

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Old 09-22-2004, 05:53 PM
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Default RE: Patriot/YS45 pipe setup

Here's a few pics showing the pipe length. I'll try the 9x9, 10x7 & 10x8 props with the pipe at the same length & see what works best. How much do these tuned pipes effect fuel consumption? Read somewhere that when setup right there is a healthy spray of unburnt fuel. I put a 12 oz fuel tank under the cockpit expecting 10 - 12 minute flights but all I'm getting is 7 minutes, set my radio timer for 6 minutes so I'll have 1 minute reserve for landing. Is this high fuel consumption due to a maladjusted pipe or is this just the nature of tuned pipes?
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Old 09-22-2004, 07:35 PM
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Default RE: Patriot/YS45 pipe setup

No problem there...From what you showed there, the pipe is actually set closer to 12.5".

Measurement should be a path from the glowplug, following the centerline/curve of the header. Sometimes it helps to use a piece of solder bent to the shape to get the measurement. Bend it to shape... get the length...then straighten it out and measure it.

You are good there where you are. As noted, jump up to the 9x9. Start loading it down with prop. Try the 10x7 and 10x8 too.

Yes, you will notice more fuel consumption. A small bit is unburnt. The majority of the additional fuel is converted to energy (heat/engine power). More fuel is consumed, the more HP the engine develops. Pretty simple

Yes, the gap should be small. If its running ok, leave it. Play with the prop. You can shorten the pipe .25" afterwards... if you want to be adventurous.
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Old 09-22-2004, 07:43 PM
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Default RE: Patriot/YS45 pipe setup

Thanks for the replies Bob.
I'll try the props first, may be a few days as the LHS may have to order the 9x9 & 10x8 props. Don't want to cut it too short. Will keep you posted with results.
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Old 09-22-2004, 08:15 PM
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Default RE: Patriot/YS45 pipe setup

Bob how was the performance with the Jett-stream on the YS? Kinda like a UT?

My header/pipe got MANGLED in a Whiplash crash awhile back...
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Old 09-22-2004, 09:55 PM
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Default RE: Patriot/YS45 pipe setup

Stupid question, If a dive is required to get an engine on the pipe, will it stay on the pipe when the load increases again?
I've got a Patriot and YS45 on the build pile. The YS will first do duty in a Venus.
Thanks, Mike
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Old 09-22-2004, 10:24 PM
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Default RE: Patriot/YS45 pipe setup

Dunno the dive question, but good choice on the Venus!
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Old 09-22-2004, 10:33 PM
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Default RE: Patriot/YS45 pipe setup

Razor..... yeah... about the same as the UT muffler...they are tuned for the same RPM range. If you wanted to go higher, the Jett SS muffler can push it over 18K with a smaller prop.

Mike,
The 'dive to unload' has to do with critical pipe tuning for maximum speed. If you want every last bit out of the powerplant, and the plane has the ability to really move through the air, you actually have to set the pipe too-short for ground operation. Makes setting the needle a real chore... and its almost a guess until you get some experience.....but this is sorta what seperates real speed/racing engine setup from sport setups. The engine will actually run sorta lousy as the plane takes off, but after the first turn, and/or a slight dive, the aircraft will accelerate fast enough to let the engine unload to the point where the pipe comes on line, then the engine will easily jump that step, and will tend to stay there during the flight.

The way I tended to set up engines/aircraft of this nature, was to use a tach prop. Selecting the same prop I intended to fly with, one would be modified with about 1/4" cut off of each tip (allowing it to turn up an extra 1000 rpm or so). I tuned the pipe for max RPM on the ground with that prop. For flying, Id put the full blade version on. And, if you do it right, you keep pretty much the same needle setting from the tach prop run.

For a sport setup, its usually wise to set the pipe so the engine JUST comes up on the pipe on the ground. As soon as it starts the take-off roll, the engine will stage on the pipe, and will stay there. In the air, the engine will be easily throttled on and off the pipe. Sure, you are giving up 400-500 rpm on the top end. But for a user friendly setup, is very worth it.
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Old 09-26-2004, 06:09 PM
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Default RE: Patriot/YS45 pipe setup

Well I got to fly my Patriot some more this weekend. Without changing the pipe length I tried the 10x7 prop & peaked at 16000 rpm, the 10x8 prop peaked at 15000 rpm. The pipe now is 13 ¼ inches long measured with a length of solder from the glow plug, along the centerline of the header & pipe to the back of the widest part of the pipe where it starts to taper back down. With the 10x8 prop it would seem to load up at about 13000 rpm on the ground & wouldn’t go any higher, but if I throttled back down & revved it up a couple of times then went to full throttle it would jump past this 13000 barrier & rev up to 14400 where I have the NV set. I think this is the point where it jumps on the pipe. Put 8 flights on it this way with no problems other than trying to slow her down for landings. Still have the OS A3 plug with about 12 flights on it with no burnouts. I was expecting it to fly a bit slower with the 10x8 vs. 9x8 since the 10x8 is unloading to about 15000 rpm vs. the 9x8 at 17000 rpm but she flew every bit as fast with the 10x8 & shortened the take off roll to about 125 feet off grass. Had the LHS order the 9x9 prop, should get them in a couple of days & should be able to test again next weekend. If this is the most speed I can get out of her I’ll be happy as she is really hauling right now, there is a slight howling I believe is from the nose retract cavity catching wind. I kept all linkages as tight as possible, hinge gaps as small as possible & sealed the hinge gaps. As yet even in power dives she is rock solid with no hint of flutter.
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Old 12-05-2004, 07:07 PM
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Default RE: Patriot/YS45 pipe setup

Anyone ever try the Venus YS 45 combo....I've been thinking of doing that combo for a while but I scrared the YS is a small prop
speed engine. I have a Venus that I currently run with a MVVS RE .49 that I run a 12+4 prop on. Anyone have an idea how the
YS will turn this prop. The MVVS does 13K at best but also has power across the whole throttle range...I don't want a YS if it is
going to fall off the pipe every time I fly half throttle..

xanaphyst
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