VansAirForceForums  
Home > VansAirForceForums

-POSTING RULES
-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
Donate methods

Point your
camera app here
to donate fast.

  #31  
Old 05-24-2021, 07:15 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 6,326
Default

Quote:
Originally Posted by jcarne View Post
I should probably just let go of the starter when it catches and wait until it comes to a stop if I want to continue this method. I tried finding a max RPM for the starter but no dice.
You shouldn't do that. While the bendix gear can deal with some of it (driven gear turning the drive gear), I don't believe it is designed to do that on a regular basis.
__________________
N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019
Reply With Quote
  #32  
Old 05-24-2021, 07:45 AM
jcarne's Avatar
jcarne jcarne is offline
 
Join Date: Jul 2016
Location: Worland, Wyoming
Posts: 1,818
Default

Quote:
Originally Posted by lr172 View Post
You shouldn't do that. While the bendix gear can deal with some of it (driven gear turning the drive gear), I don't believe it is designed to do that on a regular basis.
Ya I did a bit more research on the matter. It would appear that many of the starters have a pinion catch/release mechanism for this very reason (when engine spins faster than starter). It essential disengages the starter gear from the shaft and lets it free spin. However, I don't think my starter has this feature so I will modify my method to avoid any problems.
__________________
Jereme Carne
PPL
RV-7A Flying as of 03/2021
Exempt but gladly paying!

Last edited by jcarne : 05-24-2021 at 07:50 AM.
Reply With Quote
  #33  
Old 05-24-2021, 08:17 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 6,326
Default

Quote:
Originally Posted by jcarne View Post
Ya I did a bit more research on the matter. It would appear that many of the starters have a pinion catch/release mechanism for this very reason (when engine spins faster than starter). It essential disengages the starter gear from the shaft and lets it free spin. However, I don't think my starter has this feature so I will modify my method to avoid any problems.
It doesn't really disengage. It works in concept like your ratchet; Torque applied in one direction and free spinning in the other. However, imagine attaching your ratchet to your drill spinning 800 RPM. How long would it take to wear out the ratchet's mechanism. It is designed predominately to apply torque in one direction and not spinning in the other. I don't design these things, so really don't know whether or not excessive free spinning has any negative effect, but without that knowledge assume that it does. I do know that it is pretty common knowledge in the engine world that it is best to release the starter drive once the engine is producing it's own rotation.
__________________
N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019

Last edited by lr172 : 05-24-2021 at 08:22 AM.
Reply With Quote
  #34  
Old 05-24-2021, 09:02 AM
jcarne's Avatar
jcarne jcarne is offline
 
Join Date: Jul 2016
Location: Worland, Wyoming
Posts: 1,818
Default

Quote:
Originally Posted by lr172 View Post
It doesn't really disengage. It works in concept like your ratchet; Torque applied in one direction and free spinning in the other. However, imagine attaching your ratchet to your drill spinning 800 RPM. How long would it take to wear out the ratchet's mechanism. It is designed predominately to apply torque in one direction and not spinning in the other. I don't design these things, so really don't know whether or not excessive free spinning has any negative effect, but without that knowledge assume that it does. I do know that it is pretty common knowledge in the engine world that it is best to release the starter drive once the engine is producing it's own rotation.
Ya disengage probably wasn't the best word. Disengage from the torque of the engine (and its speed) is what I meant. Your logic makes sense. My gut feeling is that mechanism will last a long time but I would rather not find out. I'll just change my technique a bit. Thanks for knowledge!
__________________
Jereme Carne
PPL
RV-7A Flying as of 03/2021
Exempt but gladly paying!
Reply With Quote
  #35  
Old 06-01-2021, 12:54 AM
charrois charrois is offline
 
Join Date: Jan 2019
Location: Legal, AB
Posts: 20
Default

As another followup, I tried my idea of doing the sweep technique with the boost pump on during a hot start. It didn't work as well as I'd hoped - the engine still would catch and die after the first attempt. And since by then the mixture was partially advanced with the boost pump on, I'm guessing that the cylinders would get partially flooded before I could bring the mixture back to ICO. Whatever the reason, it would take 3 or 4 attempts to get the engine started this way.

What seems more reliable is to pressurize the lines with the boost pump and mixture at ICO (so the cylinders don't get flooded) and then with the boost pump off, sweeping slowly from ICO to rich until it catches. Almost always, it will quit after the first attempt (I presume there is still vapour in the lines). But if I re-pressurize the lines and try again, usually it starts and stays running the second time. If not that, the third.

It may not give warm and fuzzy feelings to my passengers when the engine takes a couple of tries to get started, but at least it seems to be pretty consistent and I avoid the lever dance by doing a flooded start.
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 03:41 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.