DMcQuinn

My Feedback: (13)

My 4 year-old 3W 100 B2 will only turn up to 5700 rpm with the MSC 27x12 prop (wood). I don't have much to compare to, but I read about guys getting well over 6000 with similar diameter props. Does this seem a little anemic? I have peaked the HS NV and this is the best I can get with this prop. I'm running 100-1 Amsoil and Johnson mufflers. The engine has probably around 30 or 40 gallons of fuel thru it. Tach is a glo-Bee of unknown calibration. Pointed at my flourescent light it reads 3600 exactly, so I have some confidence it it.

Bryant330L

My Feedback: (126)

That sounds like a lot of prop to me. For one thing the MSC props really pull hard, but don't turn a lot of rpms. I think a 27-10 would be a better prop for that engine, maybe something like a Menz or Airwild NX if you prefer wood. I bet if you put one of those on there your rpms would boost up well past 6000 and into a more powerful range for that motor.

russian

My Feedback: (23)

Yes! Use 27X10 and you'll get 6000 rpm or more. I use 3W27X10 which is the same as MenzS 27X10 and my engine runs great. Looks like 27X10 is the perfetct size for this motor.
Thanks

barryb-RCU

I agree. Sounds like too much prop to me. I wouldn't believe any 100 CC motor would turn an MSC 27x12 much over 5700, even if I saw it with my own eyes.

Huge props are trendy and people feel like they give them bragging rights, but the most common thing I tell a person after flying their gas IMAC or 3D plane is that it would fly better with a smaller prop.

On the 3W100 I'd probably fly a MenzS 26x10 or a Mejzlik 26x10 or 12. I'd only go up to an MSC 26x10 or a MenzS 27x10 if the plane weighed >30 lb and you flew lots of 3-D.

This is just my opinion. I like a prop that doesn't overly load the motor, which spins up quickly, and for which you can tell the difference between half stick and full stick.

I've found that for 100 CC motors, if it's turning less than 6200 RPM at a minimum on the ground I don't like it's performance in the air. 6300-6400 is ideal.

3D Joy

It is not only your opinion, it is mine also !

epc

My Feedback: (33)

Dmcquinn:

Use the 3W 27x10 that I sold you , I was getting 6280 with my 3w 100 and that prop.
The 26x12 I never tached it.


epc.

IanB

My Feedback: (1)

I get 6600 nwith an msc 26x10 on my 2 1/2 gallon old 3w106

Msc's are a much bigger load than most other props .........prop it so you get mid 6k on the ground then you'll see some fur fly

Kindest regards IanB

DMcQuinn

My Feedback: (13)

Thanks, all. I have swapped out the MSC prop for a 3W 27X10. I will tach it this weekend, hopefully.

DMcQuinn

My Feedback: (13)

OK, I removed the MSC 27x12 and put on the 3W 27x10. The peak rpm with the MSC 27x12 prop was 5700 and I richened it up so that it ran at 5400. With the 27x10 and without touching the needles, the rpm increased from 5400 to 5700. I did not re-peak the needle valve and then back it off again, but chose to use my limited time to fly it as-is. I have just posted a related thread about how this same engine acts up after 15 minutes of run time. 5700 seems too slow for this engine. I believe if I had had time to peak it out, it may have gotten to 6000, but I like to run a few hundred less than peak.

epc - you say you got 6280 with this same prop. I assume you mean 6280 was at fully peaked out. Do you tend to run your 3w at this needle valve setting or do you richen it up a few hundred?

OSilfa

My Feedback: (2)

If you got 5700 with a MSC 27x12,you will get 6,300rpm with the 3w 27x10 +o-.

I get with my 3W 100 QS with 3w27x10 6400rpm.

Oscar Silfa

epc

My Feedback: (33)

That was with about 200 rpm on the rich side.Peak rpm with that prop should be around 6400-6450.

Check if your carb. butterfly is completely open when you're at full throtle , sometimes simple things like this drive us crazy.

But 5700 is definetely too low for that motor-prop combo.

epc.

DMcQuinn

My Feedback: (13)

Thanks. I just checked the throttle butterfly and it goes full open (parallel to the airflow). I will peak it out next time and check the rpm. Or I may pull the cans off and check for stuck rings again.