Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
please all MZ2 Mosquito owners... Reply
#21
Oh I forgot.

In 1998, I was at Kermit Weeks' Fantasy Of Flight in Polk City, FL... for a seminar on using 2-stroke engines in helicopter. It was taught by THE MAN of 2-strokes in helicopters, B'J. Schramm.
He spent 2 or 3 hours on the subject going into scientific detail. He provided all kinds of slides and other graphics to illustrate this "starving for oil" phenomenon that is unique to helicopters.

I promptly came home to Georgia and changed the NEEDLE-JETS in the Mini-500 we had.

BC
Reply
#22
Brian,
I agree if you roll the throttle to the idle stops during auto those are the jets in use - if you aren't getting hot at idle on the ground there shouldn't be an issue as its the same rpm in an auto - your statement
* if you do a half throttle descent for 1 minute, THE PISTON GOES UP AND DOWN 6,200x,.... soon as you roll it off out of the mains you transition to the needle jetting or down to the idle jets the ratio remains the same - Its linear scale you reduced the power requirements and you have to also reduced the fuel and lubricate requirement by the same percentage to maintain the same rpm because it pounds of fuel per horse power hour - BTU requirements - your reducing load / horse power requirements (pitch) - when go into the auto therefore the fuel/lubricant demand is being reduced linear to power requirements - you don't need the extra lubricant or fuel because you've reduced the internal heat that was created at full power at (the higher power setting)

Reply
#23
ENGINE RPM REMAINS STABLE AT 6,200 FROM THE TIME YOU PICK UP INTO A HOVER UNTIL YOU SENT DOWN AND LOWER THE COLLECTIVE. (unless you are in an autorotation or your engine quits)

When you say " when you roll the throttle off the engine rpm diminishes it wont maintain 6,200 rpm at half throttle" you are very mistaken here. Anytime in flight except autorotation, your engine is turning 6,200.

The danger is not at idle during autos. The danger is during powered descents between 25% and 75% power. Also called midrange. Also is the zone of high ENGINE RPM, and low throttle.

When you think of autos, think IDLE JETS. When you think of powered descents, think NEEDLE JETS.
Reply
#24
edited / corrected - got in a hurry
Reply
#25
Are you seeing it now?
Reply
#26
It would ONLY BE A LINEAR SCALE like you speak of, if ALL variables (Engine RPM/Throttle Opening/EGT) were ALL increasing and decreasing together.
Since RPM is staying high while the other two variables change...THE FUEL/LUBRICATION NEEDED IS NOT LINEAR.
Reply
#27
Who the yell has time to monitor their EGT's while auto-ing? hmmmm.....let's see.....roll throttle off...drop collective....pull back on cyclic to establish auto....adjust yaw.....watch for LZ.....manage your rotor RPM with collective and or cyclic....watch how fast ground is coming up....keep your airspeed up....ground is getting close....concentrate on pulling everything back together to do a real nice power recovery at 10 feet or so...OH Yeah, I almost forgot...what's the EGT's doing? LOL
Reply
#28
We were not discussing autos at all. We were discussing getting hurt because you don't have the right midrange jets in.
Reply
#29
bryancobb - 2/22/2011 3:25 PM

We were not discussing autos at all. We were discussing getting hurt because you don't have the right midrange jets in.

Again, where is there evidence of our MZ engines having problems with the mid range?
Did someone seize an engine because of this? Please don't respond with a Rotax analogy.
Skeeter
Reply
#30
hey guys, reading this post here I feel compelled to speak up. First every thing the Brain Cob poster said is absolutely TRUE. All 2 stroke engines are extremely sensitive to improper jetting. All of them. doesent matter if its a rotax, a hirth, a MZ, or any other one. FYI a reed valve 2 stroke engine has the most horsepower to displacement ratio of any other 2 stroke engine designs( piston port type or rotary valve aka rotax 582) so you should be even more vigilant about egt's and what they mean as to what is actually happening in that loud buzzing thing behind yer seat.
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)