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  #11  
Old 06-13-2016, 03:12 PM
jswareiv jswareiv is offline
 
Join Date: Dec 2006
Location: New Orleans, LA
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Quote:
Originally Posted by n982sx View Post
I'm having my G3x Touch system harness built by Stein right now and have just started going over all the manuals in some detail. I had not noticed the screen capture feature, that's a nice to have.

I have read about the % of power calcs and was wondering how accurate they may be. Hoping that they can be calibrated fairly close.

I did notice the aileron trim and was wondering about that. Just the next problem on the list. Keep up the work on the gremlins and let us know how you are doing.

Real world data is always nice to have.
I spoke to Garmin about the % and they believe it is correct since 24 square is 75% of power and I was 21.8/24. They also calculate in Fuel Flow and OAT to come up with the %, so that number should be pretty close.
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  #12  
Old 06-13-2016, 03:36 PM
Barneybc12d Barneybc12d is offline
 
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Stoney - keep the posts coming - great motivation for 14 builders.
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  #13  
Old 06-14-2016, 12:12 AM
Marc Bourget Marc Bourget is offline
 
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Location: Stockton, California
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Stoney Said: " We probably should have done the pressure test with the mufflers on, then without."

Might be easier to temporarily slip something over the exhaust that would occlude the exit same as the mufflers.

See if you can achieve 5.5" H2O Delta P (top/bottom of baffles) at about 100 mph (100-105) with the exits blocked down.

mjb
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  #14  
Old 06-14-2016, 04:41 AM
stevep stevep is offline
 
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Think i may have been wrong about lower RPM equals more TAS. All a function of altitude, drag and power. Found this on an earlier thread.

Hartzell Two Blade HC-C2YK-ABF/F7666A-4 on an RV-6A from http://www.lessdrag.com/lycomingpropeller.html

RPM 2700 2500 2400 2300
2500' 205 205 198 193 Equal at 2700 & 2500
5000' 201 202 200 198 Slower at 2700 than 2500
7500' 200 197 196 194 Faster at 2700 than 2500
10000' 194 196 194 193 NO FASTER THAN AT 2400
12500' 185 191 190 187 NOT AS FAST AS 2300
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  #15  
Old 06-14-2016, 05:59 AM
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DanH DanH is offline
 
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Quote:
Originally Posted by Marc Bourget View Post
See if you can achieve 5.5" H2O Delta P (top/bottom of baffles) at about 100 mph (100-105) with the exits blocked down.
Standard day maximum available dynamic pressure is 4.79" H2O at 1000 feet and 87 KTAS (100 MPH true). In rough terms, multiply by 0.8~0.85 for a good upper cowl static pressure rise, 0.6 being more like a GA average (see NASA 3405). So, about 4" delta would be a maximum if the lower cowl volume was at freestream static....which it may not be with the exit blocked. A delta of 5.5" would probably need 110~115 KTAS.

A detail; upper cowl pressure rise increases as the system exit is reduced, so the delta pressure change with a change of exit area, although significant, may not be as large as one might assume at first glance.
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Last edited by DanH : 06-14-2016 at 06:05 AM.
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  #16  
Old 06-14-2016, 09:32 AM
Marc Bourget Marc Bourget is offline
 
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To add a bit to Dan's post, I feel the key is Lyc's cooling specification, which I believe is 5.5" H2O for an 0-360. (from memory). You won't get that at lift-off, but it is the target for cooling at full power.

FWIW
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