Hawk21

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What rpm are you guys getting with a FPE 3.2 and what prop??

ljones5000

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I get about 7300rpm with a 22X8 PT CF prop. Engine is two years old and runs perfect. It's on a SIG Sundancer.

I went out in the yard and cranked it this morning to be sure and it's a solid 7300.

rcbill

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Last fall mine was turning a NX at 6800. The engine started missing and running weird. Turns out I need a new CH ingnition on it.... The engine has run flawless other than that. It's about 3 years old.... Bill

Bass1

rcbill, A guy in my club had a similar problem with his FPE 3.2 and it ended up being a semi-melted shielding on a wire from the sensor. It was too close to the muffler and the wire started to degrade from the heat and was missing and running weird at mid to full throttle. When the wire was repaired (and secured away from the muffler) all was well again.

ram3500-RCU

My Feedback: (221)

Very good post. Thanks for the observation. Something to watch out for.

rcbill

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Bass 1,
Thanks for the input about the burned plug wire. When I got home from the field the day I had the ignition trouble I swapped the module with another plane that was running. The dead spark followed the ingnition module so that sort of confirmed the burned out module. The plug wire was in good shape. I still have to order a new module or have the old one replaced. Thanks Again..... Bill
PS: I would have replied earlier but my phone line was down and just got it repaired....

tflame

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Hello Rcbill
Please tell us what prop size you were using when it was turning 6800Rpm. We are tuning one and would like to have a reference on what Rpm we should be closed to or getting.

rcbill

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Hi Tflame,
Sorry about the prop size. It was a NX 22x8 turning 6800+. I might have been able to squeeze a couple more RPM out of it but decided to leave it there. It's installed on a GP 1/3 Pitts that I don't fly very often. I had to run a line from the carb diaphram into the fuse or the engine would go extremely rich the second the wheels took to the air. The engine turns about the same RPM as my DA 50 but spools up a little slower. It pulls the Pitts around with no problem going vertical at 17.5 pounds. I will probably put it into a Sukuoi over the winter months. All in all its always been dependable and smooth running when ever I took it to the field..... Hope this helps..... Bill

ljones5000

My Feedback: (2)

The wood props won't turn quite as much as the carbon fiber; I used to run a Bolly wood 22X8 and it wouldn't turn more than 6700 to 6800 rpm. It pulled the plane just fine, however.

Hawk21

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have someone try a 23x8 or it is to much for the engine?

rcbill

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I have tried the 23x8 Xoar on my DA 50 but not my FPE and I didn't care for it. I didn't like the way it slowed down the spool up and with the 22x8 Xaor or the NX it sill had plenty of power on my Edge (DA 50) and my Yak (Brillelli 60cc). A lot of guys love the 23x8 Xoar. I just felt it loaded the engine down a tad too much....
Here's what I have been doing with a new engine and plane. I put on a 22x8 Zinger for the first few flights just to make sure if I have an unexpected landing from the engine dying or a crappy landing, I don't screw up one of my good props. Then I change over to one of my better props. I'm sure it's a matter of personal preferance but I would at least start out with something like the 22x8 and I don't think you will be sorry.... Bill

tflame

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Hello Rcbill
Since you used the 23 x 8 XOAR in your DA-50 any chance you might remember the RPM it turned with that prop? We are tuning the FPE 3.2 but a friend has a DA-50 and would like to know the number as a reference. I think he is using a 22 x 10 CF Menz I haven`t checked with him. We had to solder a fitting to the diaphram cover of the FPE to route a piece of tubing to the fuse and a balsa box. Engine would go rich in flight.

Tired Old Man

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The FPE, Fox, and Brison 3.2 are all based on the same Sachs basic design. Essentially so does Taurus but there are some differences that set it apart and above the others. One thing to note is that the rpm numbers will be all over the spectrum with some of the wood props. NX and Xoar will provide somewhat lower numbers, where Menz will generally provide higher. The wide props like MSC will have even lower rpm numbers but provide tremendous amounts of thrust. Carbon props provide higher rpm levels but may not have consistent thrust levels or response in various rpm areas. All with the same standard sizing of 22-8. The two props that I've tested with the most consistent performance and rpm counts are Menz and Mejzlik. Because of that consistency those are the two prop manufacturers I use for establishing base line rpm numbers when experimenting with props and sizes.

A 10 pitch will load the engine more and provide more speed than an 8" pitch. You have to determine what type of flying you intend to do when considering pitches. If you want to go fast, use a higher pitch, and perhaps a smaller diameter. If you want more 3d, then lower pitches with more diameter.

Getting back to the Sachs 3.2 particulars, if you are hitting anywhere from 6,800 to 7,400 you're in the power band. Better if in the 7,000 to 7,400 range. That's where the engine produces it's best performance. You can go higher for racing, of course. They will handle up to about 13-14,000 rpm before letting the bottom go.

rcbill

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Thanks for that input Pat Roy,
It's always nice to read what you have to say about the props and engines and oils etc. I may not post much but always appreciate when you add to the questions at hand.
There are few guys like Hanson and Pe Prievers (spelling??) and RC Bugman that I always look forward to reading....
Tflame,
I did not tach the 23x8 props. I did fly it and even though some of the guys at the field run them, I thought it was just a tad too much load. I remember some making a post in the engine forum some time ago. He said "just because an engine can turn a bigger prop doesn't mean it should". I just like the snappier response from my engines and as long as I have enough power to do "whatever", I'm a happy camper.... Bill

tflame

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Thanks for the info Pat and Rcbill. I don`t have much experience with the gas engines. I`m just tring to learn since in the future I`m going to be buying a gas engine for a clipped wing mustang and also want to help my buddies. I do have experience with 2 stroke glow engines.Thanks again.