Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

TT46 rpm Question.

Reply

Old 07-10-2009, 07:08 AM
  #1  
Rflyin
Senior Member
Thread Starter
My Feedback: (6)
 
Join Date: Apr 2003
Location: Palmyra, MI
Posts: 131
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default TT46 rpm Question.

Hello,
Is there a rpm "Sweet spot" that I should shoot for on this motor? It has stock bearings, Ultra Thrust, and will be club racing on a Viper. I ran a 9x7 and was in the low 16's then tried a 9x6 and rpm's jumped into the mid 18's.

Thanks,
Rick
Rflyin is offline  
Reply With Quote
Old 07-10-2009, 08:37 AM
  #2  
still4given
 
still4given's Avatar
 
Join Date: Jan 2006
Location: Victorville, CA
Posts: 1,582
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: TT46 rpm Question.

I would stick with the 9x7. It is going to unload in the air. If you launch at 18K+ once it unloads it will likely be too high. Are you running the sport or racing Ultra Thrust?
still4given is offline  
Reply With Quote
Old 07-10-2009, 08:50 AM
  #3  
Mike Connor
Senior Member
My Feedback: (5)
 
Mike Connor's Avatar
 
Join Date: Jan 2002
Location: Tulsa, OK
Posts: 2,025
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: TT46 rpm Question.

My TT Pro 46 would turn an APC 9x7 16,000+ with the stock muffler. I am also interested if you got the short racing muffler or the standard on.
Mike Connor is offline  
Reply With Quote
Old 07-10-2009, 10:13 AM
  #4  
Rflyin
Senior Member
Thread Starter
My Feedback: (6)
 
Join Date: Apr 2003
Location: Palmyra, MI
Posts: 131
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: TT46 rpm Question.

Its the Sport muffler.

Rick
Rflyin is offline  
Reply With Quote
Old 07-10-2009, 11:05 AM
  #5  
ChrisAttebery
Senior Member
My Feedback: (15)
 
ChrisAttebery's Avatar
 
Join Date: Sep 2004
Location: Gilroy, CA
Posts: 937
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: TT46 rpm Question.

You probably need to go up in pitch as the sport muffler is tuned lower. Try a 9x8 and see if it yields more top end.
ChrisAttebery is offline  
Reply With Quote
Old 07-10-2009, 03:14 PM
  #6  
still4given
 
still4given's Avatar
 
Join Date: Jan 2006
Location: Victorville, CA
Posts: 1,582
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: TT46 rpm Question.

I still think once the prop unloads that 9x7 will jump on the pipe and turn up where it likes. I know Bob always suggests to launch the Jett 50 at the mid 16K on the ground. The Pro 46 will pull a 9x8 just fine too. It really depends on the airframe. A 10x6 isn't a bad choice either.

Blessings, Terry
still4given is offline  
Reply With Quote
Old 07-10-2009, 04:15 PM
  #7  
ChrisAttebery
Senior Member
My Feedback: (15)
 
ChrisAttebery's Avatar
 
Join Date: Sep 2004
Location: Gilroy, CA
Posts: 937
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: TT46 rpm Question.

My experience with the Jett "sport" tuned muffler was that it was tuned for around 14500-16000. You want to be taching around 14000-14500 on the ground so that you're getting close to the maximum tuned rpm in the air. The viper should unload pretty well.

My understanding is that the UT and Jett sport mufflers are pretty much tuned to the same rpm.

It's a $2 prop. If nothing else it's a cheap experiment.
ChrisAttebery is offline  
Reply With Quote
Old 07-10-2009, 09:29 PM
  #8  
Rflyin
Senior Member
Thread Starter
My Feedback: (6)
 
Join Date: Apr 2003
Location: Palmyra, MI
Posts: 131
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: TT46 rpm Question.

Hello,
Thanks for all your replys. How will the short muffler change things. I didn't know there was one.

Thanks,
Rick
Rflyin is offline  
Reply With Quote
Old 07-10-2009, 10:17 PM
  #9  
vicman
My Feedback: (10)
 
vicman's Avatar
 
Join Date: Dec 2002
Location: Valdese, NC
Posts: 9,910
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: TT46 rpm Question.

I'm curious why you don't want to change the rear bearing?
The 18K threshold is pretty critical from my first hand experience (that I don't care to repeat). I also agree that if you are going for all out speed you are going to see nice results from the 9x8
vicman is offline  
Reply With Quote
Old 07-10-2009, 11:14 PM
  #10  
Rflyin
Senior Member
Thread Starter
My Feedback: (6)
 
Join Date: Apr 2003
Location: Palmyra, MI
Posts: 131
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: TT46 rpm Question.

Changing bearings is an option I was just trying to get the best out of what I had. In our group the better pilot will beat the faster plane.

Rick
Rflyin is offline  
Reply With Quote
Old 07-10-2009, 11:14 PM
  #11  
Mike Connor
Senior Member
My Feedback: (5)
 
Mike Connor's Avatar
 
Join Date: Jan 2002
Location: Tulsa, OK
Posts: 2,025
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: TT46 rpm Question.

ORIGINAL: Rflyin

Hello,
Thanks for all your replys. How will the short muffler change things. I didn't know there was one.

Thanks,
Rick
Bob B with Jett says:
-
"Jett tuned mufflers
Just for reference, on the 40-60L size mufflers.... when used on the Jett .40/.46/.50/.60L engines (and with other engines typically)
Standard is designed for between 15,000 and 18,000 rpm (minimum and max suggested ground peak rpm)
SS muffler is designed for 17,000 and 19,500 rpm (target for the 60LX engine)
Black q-500 racing muffler 18,000 - 20,500
Usually best to prop lighter - allow more rpm. Do not lug it down below the bottom limit."
-
Your UT muffler is similar to the standard Jett, maybe a tad shorter. The short muffler is timed for a higher rpm then the engine and may not be the best choice. I would keep what you have. I would have expected a little more rpm with a 9x7
Mike Connor is offline  
Reply With Quote
Old 07-10-2009, 11:26 PM
  #12  
bob27s
My Feedback: (19)
 
bob27s's Avatar
 
Join Date: Apr 2002
Location: Cleveland, OH
Posts: 5,576
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: TT46 rpm Question.


ORIGINAL: ChrisAttebery

My experience with the Jett ''sport'' tuned muffler was that it was tuned for around 14500-16000. You want to be taching around 14000-14500 on the ground so that you're getting close to the maximum tuned rpm in the air. The viper should unload pretty well.

My understanding is that the UT and Jett sport mufflers are pretty much tuned to the same rpm.

It's a $2 prop. If nothing else it's a cheap experiment.

Jett-stream muffler TT40 - 14,500 peak ground rpm is the very bottom limit you want to prop to... launch about 14,000 even. Engines like the 46AX and the OS55AX work well down here because their torque will allow the engine to get up around 15,500-16,000 when in flight and the engine unloads.

On the TT46pro and TT40pro, 9x7 sport prop, the target is 16,000 ground peak (usually slightly higher) , launch about 600-800 down from that. Some folks prefer to use the 9x8 or a 8.75x8 and set it around 15,500 ground peak. The engine will unload up into a good range either way.

For reference, my stock TT40 engines (for 424 racing) with stock muffler and APC 9x6 all turn upwards of 16,500 ground peak and launch at 16,000. I set up the TT40 and jett-stream for the same rpm targets, but just increase the prop size to 9x7 or 9x8.

The ultra-thrust muffler should end up using the same props in the same range. Look for 15,500 - 16,500 ground peak rpm, back off at least 600-700 rpm for launch, and you will be on the mark.

(of note, the "racing" muffler is tuned to work at a minimum of 16,500 ground peak and settles in best around 17,500 - 18,000. In flight unload will be 18K+. Although the engine will do it, I personally would avoid turning the TT46 up that high even with a rear bearing change)
Bob
bob27s is offline  
Reply With Quote

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


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service