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.


Go Back   VAF Forums > RV Firewall Forward Section > Traditional Aircraft Engines
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #11  
Old 08-04-2021, 08:05 AM
DanH's Avatar
DanH DanH is online now
 
Join Date: Oct 2005
Location: 08A
Posts: 10,750
Default

Quote:
Originally Posted by lr172 View Post
There is one lug that is about .020" larger than the others and is called the index lug. However, this is for indexing the flywheel and NOT the prop. One flywheel hole is .020" larger and the flywheel can only go on one way; This ensures that the TDC markings on the flywheel are accurate. The larger diameter only protrudes about an 1/8" past the crank flange and doesn't extend past the flywheel (it steps back down after 1/8" if it is a long lug, though it is typically a short lug).
Supposedly the flywheel can only go on one way...

One of those interesting little stories out of OSH this year. A fellow had a mag failure. New mag is installed and timed in the usual manner...and the engine runs awful. Much head scratching ensues. A smart guy pulls a plug to check that TDC is actually TDC...and it's not.

Reconstructing, the timing was set at the manufacturer before the initial run-in. Engine was subsequently installed and flown a few hundred hours, without any further timing check by the builder. However, somewhere in the process the builder had removed the flywheel, and re-installed it 60 degrees off. Fast forward to OSH; when timed to the TDC mark on the incorrectly installed flywheel, it didn't run well at all at about 85 degrees of advance.

The specified diameter for the flywheel index bushing 0.0313" larger than the other bushings. The one oversize hole in the flywheel is marked with a "O" symbol so the bushing and hole can be easily paired. However, if a fella puts a small hole over the big bushing and cranks down on the prop bolts, it doesn't back the bushing out of the engine flange. It just enlarges the flywheel hole.

If it don't fit, we'll make it fit
.
Attached Thumbnails
Click image for larger version

Name:	Enlarged Hole.jpg
Views:	68
Size:	51.6 KB
ID:	14320  Click image for larger version

Name:	Enlarged Hole 2.jpg
Views:	65
Size:	52.3 KB
ID:	14321  
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
  #12  
Old 08-04-2021, 08:12 AM
moespeeds moespeeds is offline
 
Join Date: Apr 2021
Location: Cherry Hill, NJ
Posts: 156
Default

This is exactly what WW states in their documentation.

Quote:
Originally Posted by Freemasm View Post
Have heard that initially the 10 to 11-ish clocking was chosen for gaining the proper mechanical advantage for hand propping; harmonics and other considerations aside. The way things tended to develop, it's believable.

Any known truth to this? Sorry for the drift.
__________________
Moe Colontonio
Cherry Hill, NJ
RV-8 N495T
Reply With Quote
  #13  
Old 08-04-2021, 08:17 AM
DanH's Avatar
DanH DanH is online now
 
Join Date: Oct 2005
Location: 08A
Posts: 10,750
Default

Quote:
Originally Posted by moespeeds View Post
Ok so according to the above diagram, I've got the prop at B/E.

My question is, did I do it correctly?
No. Or maybe it doesn't matter.

A question....the Whirlwind does not have one small diameter hole, like a Hartzell? With the small hole, the Hartzell only goes on with the correct orientation, as below. Given you report no bushings pushed out, the Whirlwind must not have the small indexing hole.
Attached Thumbnails
Click image for larger version

Name:	ScreenHunter_882 Aug. 04 08.34.jpg
Views:	80
Size:	73.1 KB
ID:	14324  Click image for larger version

Name:	Crankpin Orientation wProp.jpg
Views:	60
Size:	35.6 KB
ID:	14325  
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
  #14  
Old 08-04-2021, 09:45 AM
NLPete NLPete is offline
 
Join Date: Sep 2007
Location: Southeastern, MN
Posts: 26
Default

I have a WW 200RV bolted to an ECi IO-360 assembled by a reputable engine shop. The only way it would bolt on is with the prop 12-6 at TDC. It's been flying for about 350 hours or so and nothing has fallen off yet. I've been flying along fat dumb and happy until I read this thread. Now I'm fat dumb and curious. Has 12-6 caused any issues I should know about? I won't be hand propping so that's not an issue with me. Thanks!
__________________
RV-8 Built and Flying
Reply With Quote
  #15  
Old 08-04-2021, 10:17 AM
Ralph Inkster Ralph Inkster is offline
 
Join Date: Feb 2008
Location: Calgary, Alberta
Posts: 1,793
Default

Maybe prop clocking is not as much of an issue for WW props. With the light weight (mass) blades, position may not be as critical - only WW would be able to answer this question.

First paragraph on 1098G reads "...When replacing flange bushings, it is extremely important that the correct size and location be observed, If a propeller is not indexed correctly, excessive propeller blade stresses may result."

Maybe Hartzell prop blades have enough weight (mass) to be concerned about power pulses/torque stresses etc. that Hartzell indexes their prop flanges & WW might not.

Maybe someone who has contacts with the prop manufacturers could call them & get the mfg official view?? Hartzell, WW, MT, & who ever else. This would be a service to the group with real information.
__________________
Ralph
built a few RVs, rebuilt a few more, hot rodded more, & maintained/updated a big bunch more

Last edited by Ralph Inkster : 08-04-2021 at 10:20 AM.
Reply With Quote
  #16  
Old 08-04-2021, 10:39 AM
DanH's Avatar
DanH DanH is online now
 
Join Date: Oct 2005
Location: 08A
Posts: 10,750
Default

Here's a clue from the Whirlwind Aviation instructions for the RV series props.

Read the note carefully. They suggest mounting with the upper blade at 10 o'clock, but they do not reference TDC.

Instead, reading further, it states "...the approximate 7 o'clock position where the magneto snaps and the ignition fires". By extension, that statement tells us the relationship between TDC and prop position, given the impulse coupling would trip around TDC. The suggested clocking would be just like the Hartzell two-blade.

I say "suggested" because the Hartzell will only go on one way (the small hole in the hub can only be over a flange bushing), but if the Whirlwind has six holes with clearance for bushings, it will go on three ways.
Attached Thumbnails
Click image for larger version

Name:	Capture.JPG
Views:	86
Size:	44.9 KB
ID:	14327  
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
  #17  
Old 08-04-2021, 11:00 AM
Ralph Inkster Ralph Inkster is offline
 
Join Date: Feb 2008
Location: Calgary, Alberta
Posts: 1,793
Default

Wow. WW is a cryptic as Lycoming! They could have explained that in a much easier way...
__________________
Ralph
built a few RVs, rebuilt a few more, hot rodded more, & maintained/updated a big bunch more
Reply With Quote
  #18  
Old 08-04-2021, 11:02 AM
Freemasm Freemasm is offline
 
Join Date: Nov 2017
Location: Orlando
Posts: 719
Default

Quote:
Originally Posted by NLPete View Post
I have a WW 200RV bolted to an ECi IO-360 assembled by a reputable engine shop. The only way it would bolt on is with the prop 12-6 at TDC. It's been flying for about 350 hours or so and nothing has fallen off yet. I've been flying along fat dumb and happy until I read this thread. Now I'm fat dumb and curious. Has 12-6 caused any issues I should know about? I won't be hand propping so that's not an issue with me. Thanks!
Kinda what Ralph said and a little more. Four bangers don't have any combustion event overlap. This makes for strong energy impulses = not so smooth ops. This is a known problem where blade metal fatigue can be an issue. CW'd cranks help but are not a cure-all. The composite blade material should be a plus.

Find out why your clocking is off. Stick with the OEM recommendations. Stay safe.
Reply With Quote
  #19  
Old 08-04-2021, 11:29 AM
moespeeds moespeeds is offline
 
Join Date: Apr 2021
Location: Cherry Hill, NJ
Posts: 156
Default

Jay at WW told me TDC #1, blade at around 10 O'Clock. That's where I got that from. I have a call into him today to clarify. Pisses me off, because the way it originally was mounted looks like it was correct, but we changed that based on the phone convo with him.

Quote:
Originally Posted by DanH View Post
Here's a clue from the Whirlwind Aviation instructions for the RV series props.

Read the note carefully. They suggest mounting with the upper blade at 10 o'clock, but they do not reference TDC.

Instead, reading further, it states "...the approximate 7 o'clock position where the magneto snaps and the ignition fires". By extension, that statement tells us the relationship between TDC and prop position, given the impulse coupling would trip around TDC. The suggested clocking would be just like the Hartzell two-blade.

I say "suggested" because the Hartzell will only go on one way (the small hole in the hub can only be over a flange bushing), but if the Whirlwind has six holes with clearance for bushings, it will go on three ways.
__________________
Moe Colontonio
Cherry Hill, NJ
RV-8 N495T
Reply With Quote
  #20  
Old 08-04-2021, 04:08 PM
scsmith scsmith is offline
 
Join Date: Jan 2008
Location: Ashland, OR
Posts: 3,084
Default

Moe, I just did an oil change today so I checked. My WW200RV prop on my IO360 is exactly vertical when the TDC mark on the flywheel is lined up with the case split. I’m pretty sure mine was drilled so that it would only go on one way.

Note that this is consistent with what NLPete said above.

Note also that this causes the engine to stop with the prop horizontal (3--9 position) which is consistent with what DSmith said the next post.
__________________
Steve Smith
Aeronautical Engineer
RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet" Flying since Sept. 2009
Hobbs 700
also
1/4 share in 1959 C-182B (tow plane)
LS6-15/18W sailplane SOLD
bought my old LS6-A back!!
VAF donation Dec 2021

Last edited by scsmith : 08-05-2021 at 05:05 PM.
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 05:59 PM.


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.