REFLECTOR: N4PE Testing Status

[Jerry Teitsma]

Larry - I think of you often and the good advice that you gave me to help me get over my high oil temp problems.  As you may recall, you advised increasing spring pressure in the oil by-pass, using 3/4 inch or greater vortex generators in front of the NACA scoops on top of the plane and measuring the oil temps in a galley port intended for that use.  I did them all at once so I can't tell you which one had the greatest affect but my oil temperatures went down to the same levels that you are seeing and cylinder temps went down as well to about the same 360 degrees that you are reporting.  I just switched to Shell 15W50 (I think this is the weight I used) semi synthetic oil and am part of the way through an annual.  I am installing a Right Angle of Attack indicator before reassembling the plane.  Best to you.  JT 


Jerry Teitsma, RRC, CCCA 
RCI Education 
PO Box 796 (mail), 36 Lodgepole Ct. (shipping) 
Granby, CO   80446 
Phone:  970-531-9641 
jteitsma @comcast.net 
----- Original Message -----
From: "Laurence Coen " < lwcoen @ hotmail .com> 
To: "Velocity Aircraft Owners and Builders list" <reflector@ tvbf .org> 
Sent: Wednesday, April 10, 2013 10:45:27 AM 
Subject: Re: REFLECTOR: N4PE Testing Status 


Brian, 
  
Just rich of best power is real close to peak cylinder head temp.  Is your mixture not adjustable in flight?  My Franklin is carbureted   so mixture works in a conventional manner.  My exhaust temperature runs 1350F at take-off power and I can climb to 10,000 feet with peak CHT of 360F. My oil will peak at 210F and then settle at 180-190F during cruise.  During climb I adjust mixture every 1000 ft or so to maintain EGT at 1350F.  This prevents going over rich during climb.  My armpit scoops are moved out 3/4" from the fuselage and I added an internal throat shaped like a ram jet to improve pressure recovery.  With that set-up low CHT is more of a problem then high.  I struggled with high oil temp early on and solved that by placing two vortex generators ahead of the oil cooler inlet (3/4" tall) and changing from break-in oil to Exxon Elite.  Putting another 50 hours on the engine made further improvements. 
  
I had a plenum duct pop off during Vne testing and had to abort a test run.  I have a split plenum so only the even numbers got hot.  A couple of small sheet metal screws thru the duct into the plenum might be a good idea. 
  
I don't think cylinder baffles on a Franklin make sense with their fin configuration.  I do think your mixture is a problem. 
  
Keep smiling, it fly's doesn't it. 
  
Larry Coen 
N136LC 




From: Brian Michalk 
Sent: Tuesday, April 09, 2013 10:44 PM 
To: Velocity Aircraft Owners and Builders list 
Subject: REFLECTOR: N4PE Testing Status 

As I mentioned in my earlier email, my last flight was cut short due to high oil temps. 

I've had five flights so far, and after each flight have been addressing the squawks.  The biggest danger to flight so far was a manifold pressure tube that got hot in flight, and appears to have collapsed after landing with low manifold pressure.  I replaced it with a larger tube good for 250F in the engine bay.  That should keep the EFI computer happy. 

On my flights I have been having high CHT's , and of course the high oil temps that follow.  I have made several changes, but next on my list is to richen up the mixture a bit more from what I have now, which is just rich of best power.  I'm using electronic fuel injection.  I am also going to try the following: 

    • Seal up all of the gaps around the plenum. When I tuned the engine, I used leaf blowers connected to the plenum.  This was more than adequate for engine cooling, and also kept my oil temps down, so I do believe my CHT temps are the root of the problem.  With the blowers, there were obvious leaks around the plenum. 
    • Clean up the sharp corners from the armpit scoops to the engine I'm not giving up on the armpit scoops yet, and really don't want to.  I have my reasons. 
    • Reduce the timing.  I've got everything at 28BTDC until I get to 2600RPM, which advances to 32BTDC.  That should give me a little bit more headroom. 
    • Richen the mixture 
    • Cylinder baffles I can try this, but I'm not sure how it would really work.  The Franklin cylinder castings are such that there is really not much room for air to flow between cylinders.  On a Lycoming , the cooling fins go all around, but on a Franklin, the castings are much different.  It's difficult to explain, and really requires a picture.  Has anyone added the under-the-cylinder baffles to a Franklin? 





_______________________________________________ 
To change your email address, visit http :// www . tvbf .org/mailman/ listinfo /reflector 

Visit the gallery!  www . tvbf .org/gallery 
user: pw = tvbf : jamaicangoose 
Check new archives: www . tvbf .org/ pipermail 
Check old archives: http :// www . tvbf .org/archives/velocity/ maillist . html 
_______________________________________________ 
To change your email address, visit http :// www . tvbf .org/mailman/ listinfo /reflector 

Visit the gallery!   www . tvbf .org/gallery 
user: pw = tvbf : jamaicangoose 
Check new archives: www . tvbf .org/ pipermail 
Check old archives: http :// www . tvbf .org/archives/velocity/ maillist . html
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.tvbf.org/mailman/private/reflector/attachments/20130411/4aac82bb/attachment.html>