VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics


Go Back   VAF Forums > Model Specific > RV-10
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #31  
Old 10-23-2018, 12:35 AM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
 
Join Date: Mar 2005
Location: Calgary, Canada
Posts: 4,844
Default

Quote:
Originally Posted by scsmith View Post
This question seems to have gotten forgotten as the thread moved along. I think what happens is that there is some conduction heating of the intake tubes from the cylinders that heats the intake charge as it flows through the intake tubes toward the cylinder.

Make sense?
VE is the actual mass flow pumped vs. the theoretical mass flow pumped based on the rpm and displacement. The heating of the charge air in the intake tubes either through conduction at the flange or from impingement of the cooling air from the fins above on the steel tube below would be virtually immeasurable given the short time duration the charge air is in the tube between intake strokes, the small surface to volume ratio and low thermal conductivity of the steel.

I don't see that CHT would have any significant effect on how much mass flow is processed through the engine which is determined by flow restriction within the head, valves, intake and exhaust systems plus the delta P inlet to outlet (sometimes we'll have favorable or unfavorable acoustic effects helping or hindering VE at certain rpms).
__________________

Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 426.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm



Last edited by rv6ejguy : 10-23-2018 at 07:37 AM.
Reply With Quote
  #32  
Old 10-23-2018, 07:00 AM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 4,548
Default

Quote:
Originally Posted by rv6ejguy View Post
VE is the actual mass flow pumped vs. the theoretical mass flow pumped based on the rpm and displacement. The heating of the charge air in the intake tubes either through conduction at the flange or from impingement of the cooling air from the fins above on the steel tube below would be virtually immeasurable given the short time duration the charge air is in the tube between intake strokes, the small surface to volume ratio and low thermal conductivity of the steel.

I don't see that CHT would have any significant effect on how much mass flow is processed through the engine which determined by flow restriction within the head, valves, intake and exhaust systems plus the delta P inlet to outlet (sometimes we'll have favorable or unfavorable acoustic effects helping or hindering VE at certain rpms).
Completely agree.
__________________
Bill

RV-7
1st Flight 1-27-18
Phase II 8-3-18
Repairman 11-15-18
Reply With Quote
  #33  
Old 10-23-2018, 07:24 AM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
 
Join Date: Mar 2005
Location: Calgary, Canada
Posts: 4,844
Default

I'd also add, to clarify, that once the air passes the throttle plate, it's been inducted and that air will be exhausted a few milliseconds later.
__________________

Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 426.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm


Reply With Quote
  #34  
Old 10-23-2018, 08:35 AM
rdrcrmatt rdrcrmatt is offline
 
Join Date: Oct 2014
Location: Milwaukee, WI
Posts: 149
Default

Quote:
Originally Posted by lr172 View Post
I do LOP climbs when not in a hurry or when it's cool, producing more power. Don't be afraid, just pull the mixture to known LOP EGTs. The window doesn't move fast and it's not as dangerous as some would have you believe to be outside the window for short periods. Just keep leaning as you climb to maintain your target EGT. I tend to move to LOP climb after 3000' to avoid some risks.

Larry

while at WOT?
__________________
Matt
RV-10
2018 Dues Paid.
Reply With Quote
  #35  
Old 10-23-2018, 08:39 AM
Paddy's Avatar
Paddy Paddy is offline
 
Join Date: Jul 2008
Location: Chicago
Posts: 229
Default Ram Air Effect

I'll offer that the ram air effect is the primary reason for the (small) increase in MP value at top of climb as the aircraft accelerates after the comparatively slower airspeed during climb. As a result, the mixture gets (a little) leaner once cruise speed is established.
__________________
RV-10
Flying as of 10/30/16 after 8 yrs building
Reply With Quote
  #36  
Old 10-23-2018, 09:02 AM
Carl Froehlich's Avatar
Carl Froehlich Carl Froehlich is offline
 
Join Date: Dec 2007
Location: Dogwood Airpark (VA42)
Posts: 1,776
Default

Quote:
Originally Posted by Paddy View Post
I'll offer that the ram air effect is the primary reason for the (small) increase in MP value at top of climb as the aircraft accelerates after the comparatively slower airspeed during climb. As a result, the mixture gets (a little) leaner once cruise speed is established.
Not exactly.

A MP increase by ram air is the same as adding throttle to increase MP. Your servo will add more fuel. Effect on mixture will be in the grass (assuming constant altitude).

Carl
Reply With Quote
  #37  
Old 10-23-2018, 09:59 AM
Paddy's Avatar
Paddy Paddy is offline
 
Join Date: Jul 2008
Location: Chicago
Posts: 229
Default Servo Compensation

That's true - fair point, assuming that the servo sensitivity is fine enough to compensate. Consider also the injector bodies are subject to a relatively higher air pressure in the cowling as airspeed increases, so there might be a correlation there with a tiny fraction more air in the atomization stream compared to that in the climb. Interesting to ponder if nothing else...
__________________
RV-10
Flying as of 10/30/16 after 8 yrs building
Reply With Quote
  #38  
Old 10-23-2018, 10:12 AM
DanH's Avatar
DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 7,985
Default

Quote:
Originally Posted by Paddy View Post
That's true - fair point, assuming that the servo sensitivity is fine enough to compensate. Consider also the injector bodies are subject to a relatively higher air pressure in the cowling as airspeed increases, so there might be a correlation there with a tiny fraction more air in the atomization stream compared to that in the climb. Interesting to ponder if nothing else...
At WOT the bleed air delta is very low, not that it matters in this context. Pressure increases on both sides of the nozzle (cooling plenum space and within the cylinder head intake tract), thus velocity change doesn't change the delta. There is no additional bleed air to lean the mixture.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
  #39  
Old 10-23-2018, 10:34 AM
Paddy's Avatar
Paddy Paddy is offline
 
Join Date: Jul 2008
Location: Chicago
Posts: 229
Default Bleed air delta

I see that a bit differently, Dan. The bleed air delta is bound to increase as a function of airspeed in a standard induction RV10. This is because the ram air applied to the upper plenum is virtually unimpeded (disregard nacelle inefficiency), compared to the induction path to the engine. The small inlet, air filter, throttle body and relatively complex/curvy path to the cylinder head all contribute to dynamic pressure drop . The faster you go, the larger the delta between plenum and manifold pressure. This is intuitive, however I believe you may have empirical manometer data from your excellent exploration of cowl exit design that would support the numerical relationship between MP and plenum pressure.
__________________
RV-10
Flying as of 10/30/16 after 8 yrs building
Reply With Quote
  #40  
Old 10-23-2018, 11:24 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 3,326
Default

Quote:
Originally Posted by rdrcrmatt View Post
while at WOT?
Yes. I will be WOT and ROP in climb after take off. I stay ROP at the lower altitudes as more power is produced and more risks. Around 3000, I just pull the mixture to a FF of 8 GPH or so. 8 GPH is is 75% power for the 160 HP 320. 8 is a target and I don't worry if I am a bit higher and I don't worry about time spent in the leaning process, though I do it in one session to get where I want to be. I also watch the EGTs to confirm that I have settled into know LOP ranges.

No sudden engine failures nor any indication of detonation or other problems in 600 hours.

Larry
__________________
N64LR
RV-6A / IO-320, Flying as of 8/2015
RV-10 in progress
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
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

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 07:20 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.