Go Back  RCU Forums > RC Airplanes > Extreme Speed Prop Planes
Reload this Page >

Engine suggestions for GP Patriot XL with noise limits

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

Engine suggestions for GP Patriot XL with noise limits

Reply

Old 01-01-2006, 06:10 PM
  #1  
EdwardB
Senior Member
Thread Starter
My Feedback: (6)
 
EdwardB's Avatar
 
Join Date: Feb 2002
Location: Lake Orion, MI
Posts: 181
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Engine suggestions for GP Patriot XL with noise limits

One of my winter projects this year is a Great Planes Patriot XL, including with retracts. My field has a strict 94 dB at 10 feet noise restriction. What engine and exhaust combinations do you recommend that would give the best performance possible (speed of course) and still stay within this guideline? I realize I'm going to be pretty limited, but would like to do the best possible. I'd love to use a Jett, like the BSE-90L, since I've had nothing but the best experience with Jett engines. (My Jett .46 powered Something Extra is still pictured on Jett's website. Interesting combination...) But that was in a different state, at a club field where the only noise guideline was "no open exhaust." The Turbo-Jett muffler from Jett is not an option for the Patriot, IMO. I was thinking about the YS 110, as with the right prop this would probably give reasonable speed. But I've read about problems with being nose heavy with a 4-stroke, plus the YS 110 is hard to find. Suggestions? Thanks in advance.
EdwardB is offline  
Reply With Quote
Old 01-01-2006, 09:00 PM
  #2  
piper_chuck
My Feedback: (12)
 
piper_chuck's Avatar
 
Join Date: Jun 2004
Location: Columbia, SC
Posts: 8,039
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Engine suggestions for GP Patriot XL with noise limits

Noise reduction in competitive boating has become pretty important. IMPBA has a 95dB limit this year and is voting on reducing it to 92dB. Measurements this year showed that many are already below the 92dB limit. This is on engines turning 20-25K RPMs. A muffled tuned pipe on a 2 stroke can be pretty quiet.
piper_chuck is offline  
Reply With Quote
Old 01-03-2006, 03:13 PM
  #3  
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: Engine suggestions for GP Patriot XL with noise limits

Hitting 94db is tough to do with just about any stock engine.

Your best bet would be to do a combination of things

1) Engine soft mount. Use a Hyde engine mount. The soft mount is good for 2 or 3 db right off the bat. (yeah, its expensive, but worth it)

2) Jett FIRE 90L. A side exhaust is possible, but Id suggest the rear exhaust.....because....

3) Set it up with a Macs muffled quiet pipe - set up a bit on the long side for torque - 12x9 or 12x10 prop - will get down around 11,000 - 12,000 rpm (dub can set it up that way).

Other option
SJ-90L with the "T"orque muffler (the longer 120 size muffler). Again, stick with the 12x9 size prop - turn around 12K rpm.

The lower rpm is key to getting the prop noise out of the equation. The trick is to trade rpm for torque and use the torque properly.

Take a look at Bobber's speed plane build thread from this past summer.

Photo of a FIRE installation in a Patriot attached too (that is a nitro pipe - you will want the muffled pipe). Looks fairly nice.

Bob
Attached Thumbnails Click image for larger version

Name:	Ig12163.jpg
Views:	14
Size:	114.9 KB
ID:	380338  
bob27s is offline  
Reply With Quote
Old 01-03-2006, 10:31 PM
  #4  
EdwardB
Senior Member
Thread Starter
My Feedback: (6)
 
EdwardB's Avatar
 
Join Date: Feb 2002
Location: Lake Orion, MI
Posts: 181
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Engine suggestions for GP Patriot XL with noise limits

Thanks Bob!!! Great information. I'll check into the options you described.
EdwardB is offline  
Reply With Quote
Old 01-17-2006, 05:22 PM
  #5  
ArthurD
Senior Member
 
Join Date: Aug 2002
Location: Jacksonville, FL
Posts: 205
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Engine suggestions for GP Patriot XL with noise limits

Go to www.flyquiet.com and take a look at their products for lowering noise without sacraficing performance. I've been using their products for several years and the work. You'll also be impressed with the test results, and learn a lot about noise reduction.
ArthurD is offline  
Reply With Quote
Old 02-05-2006, 05:22 PM
  #6  
EdwardB
Senior Member
Thread Starter
My Feedback: (6)
 
EdwardB's Avatar
 
Join Date: Feb 2002
Location: Lake Orion, MI
Posts: 181
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Engine suggestions for GP Patriot XL with noise limits

Bob (and others!) thanks for your posts and suggestions. I've been away a bit for work and travel, but now ready to get down to business on this project. I'd love to use the Jett engines, as described, since my previous experience along with others has been so positive. One point of clarification -- what would be the advantage of the FIRE 90L with the quiet pipe, over the SJ-90L with the 120 size muffler? I would expect the FIRE with the pipe to have more power, but in the description, both seem to be targeting the same prop(s) and RPM range. Any difference in sound level between the two? There is a pretty big difference in cost and complication between the two combinations, so would like to understand better. Thanks again.
EdwardB is offline  
Reply With Quote
Old 02-06-2006, 10:36 AM
  #7  
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: Engine suggestions for GP Patriot XL with noise limits

ORIGINAL: EdwardB

Bob (and others!) thanks for your posts and suggestions. I've been away a bit for work and travel, but now ready to get down to business on this project. I'd love to use the Jett engines, as described, since my previous experience along with others has been so positive. One point of clarification -- what would be the advantage of the FIRE 90L with the quiet pipe, over the SJ-90L with the 120 size muffler? I would expect the FIRE with the pipe to have more power, but in the description, both seem to be targeting the same prop(s) and RPM range. Any difference in sound level between the two? There is a pretty big difference in cost and complication between the two combinations, so would like to understand better. Thanks again.
Edward,
The 120 muffler is fixed geometry. you have to run at the rpm it is designed to run at. In that case, around 12K peak rpm for best performance.

The muffled pipe and FIRE setup give you flexibility. You tune the system for the RPM you want to run - within the limits of the engine - and thus matched to the prop. Plus it provides a little more boost than the jett-stream muffler (more prop, same rpm). The quiet pipe is baffled - with added chambers (thus bigger than the muffler) - and is inherantly quieter. Combine this with the capability to better match the max RPM/prop, and the added boost of the big pipe, you can see where this setup might be better. And, later on, if you want to run it at higher rpm - no problem --- just cut down the header and drop in prop/pitch size.

What I described here is basically a pattern ship configuration... similar to how we use to run the Hanno .61 and YS longstroke .61 engines in pattern back in the early 1990s. Quiet, lots of power. Add in another 50% of displacement, and that is just a bonus
bob27s is offline  
Reply With Quote
Old 02-06-2006, 10:52 AM
  #8  
buzzingb
Senior Member
My Feedback: (2)
 
Join Date: Sep 2002
Location: Bruce, MS
Posts: 1,516
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Engine suggestions for GP Patriot XL with noise limits

Noise is half the fun of this hobby. I would look for a field that was noisy even if I had to travel a little. Lets face it the only sense of flying rc is sight, and sound. If you remove sound that is half of the feedback we receive. Don't get me wrong I am very aware why some fields limit noise but without noise we might as well go electric. and I am not doing that.
buzzingb 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