Tachometer Readings Post your tachometer readings for your motor in here or ask others what they are getting out of their motor/prop combos!

Jett Engineering Sport Jett 50

Reply
Old 08-19-2008, 12:14 AM
  #1
kenhiraihnl
Thread Starter
 
kenhiraihnl's Avatar
 
Join Date: Jul 2005
Location: Pearl City, HI
Posts: 603
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Jett Engineering Sport Jett 50

today was my second session for breaking in my sj50...coolpower15%, 9x7apc...17,400 (i haven't found the peak yet)...richened it to 17,040, and varied throttle between idle, midrange, and wot...fantastic engine...btw, i calibrated my tach on the fluorescent fixture over my workbench (3,600), and the tv set (1,800)...ken
Attached Thumbnails
Click image for larger version

Name:	Xu62559.jpg
Views:	21
Size:	67.9 KB
ID:	1014687  
kenhiraihnl is offline  
Reply With Quote
Old 08-23-2008, 05:55 PM
  #2
kenhiraihnl
Thread Starter
 
kenhiraihnl's Avatar
 
Join Date: Jul 2005
Location: Pearl City, HI
Posts: 603
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Jett Engineering Sport Jett 50

i ran my sj50 this morning on cool power 12.5% heli fuel (17% ultra-high viscosity syn lube), and as jett engineering/bob27s recommended, w/ a 9x6 apc...i'm closer to finding the peak - 18,330...i richened it to 17,300 to finish the break-in...needless to say, i'm very impressed with the engine...when the engine was hot, the compression was perfect...when the engine cooled down, the pinch was still very, very tight, and i had to caution my buddies when they tried to finger-flip the prop...now i just have to finish the airframe (waiting on new servos)...ken
kenhiraihnl is offline  
Reply With Quote
Old 08-23-2008, 11:22 PM
  #3
rainedave
 
rainedave's Avatar
 
Join Date: Jul 2005
Location: Richmond, VA
Posts: 6,329
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Jett Engineering Sport Jett 50

Cool. FYI, APC's safety limit for 9" props is 21,111rpm. [190,000/diameter]

David
rainedave is offline  
Reply With Quote
Old 08-23-2008, 11:35 PM
  #4
kenhiraihnl
Thread Starter
 
kenhiraihnl's Avatar
 
Join Date: Jul 2005
Location: Pearl City, HI
Posts: 603
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Jett Engineering Sport Jett 50


Quote:
ORIGINAL: rainedave

Cool. FYI, APC's safety limit for 9" props is 21,111rpm. [190,000/diameter]

David
thanks for the info...i actually wondered how much rpm the prop could take...ken
kenhiraihnl is offline  
Reply With Quote
Old 09-24-2008, 02:03 PM
  #5
bob27s
 
bob27s's Avatar
 
Join Date: Apr 2002
Location: Cleveland, OH
Posts: 5,576
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Jett Engineering Sport Jett 50


The sport jett version muffler tuning tends to drop off around 18,500 - its not going to unload much above 19K in flight - tends to work like a governor.

You are just fine with the 9x7 ........ but you probably would want to avoid flying with the 9x6.

Sounds like it is running well. Use the 9x7 for a few flights.... then move to a 9x8 or a 10x6 depending on what you want for level flight speed.
bob27s is offline  
Reply With Quote
Reply


Thread Tools
Search this Thread
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -8. The time now is 05:01 PM.