REFLECTOR: cooling

Thu Aug 15 11:40:42 CDT 2013

Scott,

Thanks for the advice, I will look into what you are suggesting, on my next trip out to the airport. I agree, I may have my baffling too tight around my # 5 & 6 cylinders. I have also already figured out that I need some sort of deflector to make the airflow make the turn to my rear cylinders. Like we are talking about, it is oblivious from my rear most cylinders running so cool. The problem with creating the deflectors, is that nothing in this part of the lower cowling is straight. There are only a lot of compound curves to attach the deflectors too. 

-----------------------------------------
Andrew Ellzey
479-631-2851 (Office)
479-531-5139 (iPhone)

From: Scott Derrick 
Sent: Thursday, August 15, 2013 7:53 AM
To: Andrew Ellzey ; Velocity Aircraft Owners and Builders list 
Subject: cooling

It makes sense the forward cylinders are running hotter than the others.  Both my IO360 and IO520 did the same.

I used updraft on the IO360 and had deflectors for the two forward cylinders,  downdraft now for the IO520 and I have deflectors  for the two forward cylinders.

The air is coming into the cowl/plenum fast and in a direction pointing straight back and has a hard time making the quick turn into and through the forward cylinders. Thus the deflectors.

1.) can you open up the seal between the hottest cylinder where it is sealed on the forward side?  A 1/4 inch gap along the cylinder wall, not the head. Just jam something in there temporarily to create a gap and go fly.  This encourages the air to flow through that cylinder. I did that to mine and dropped the temp 25 degrees on that cylinder with no appreciable rise on the others. Somebody here suggested that and it worked like a charm. 

2.) I opened up a cowl flap on my bottom cowl to lower the pressure which helped alot also.  Sense your updraft you may consider a louver over the two forward cylinders to create a lower pressure right above them.  I've seen this on quite a few pushers and pullers.

3.) Make sure your sealing really really well on the back cylinders, no gaps larger than 1/16 of an inch anywhere.

Scott

-------- Original Message --------
Subject: Re: REFLECTOR: Vortex generators location for armpit cooling scoops
From: Andrew Ellzey mailto:ajlz72756 at yahoo.com
To: Velocity Aircraft Owners and Builders list mailto:reflector at tvbf.org
Date: 08/14/2013 09:15 PM

  Scott

  I haven't done any air flow testing yet. On a Lycoming the #5 & 6 are aft most cylinders on the engine, which is forward most cylinders on our Velocities. Cylinders 1 & 3 are the forward most for the engine, which is the aft most or closest to the prop. I have been leaning some at altitudes above 3500 feet,  just to keep from burning 20 gal per hour. But I haven't tried any LOP operation. At 6,000 feet, running 24/24 I have been able to barely keep #5 under 450 degrees, my preset redline on my EFIS display, and fuel flow of 16 gal per hour. # 6 at these settings will be running about 400 to 425 degrees. All other cylinders are under 400 degrees, more in the ranges of 375 to 385 degrees.

  I will try some LOP operation the next time I get a chance to fly.

  Andy

    From: Scott Derrick mailto:scott at tnstaafl.net
    To: Velocity Aircraft Owners and Builders list mailto:reflector at tvbf.org 
    Sent: Wednesday, August 14, 2013 5:53 PM
    Subject: Re: REFLECTOR: Vortex generators location for armpit cooling scoops

    have you done a flow test to see where the air is going?  

    sprinkle some used(dark) motor oil around the scoops, be generous.

    fly in cruise for a couple minutes, land and inspect.

    Is #5 forward or rear in a Lycoming?  #5 on Cont. is rear. Rear meaning closest to prop.  I had my forwared cylinders run warmer than the others at first.  I have two deflectors in side my plenum on both, which helped. 

    Somebody suggested attempting to run LOP and map out the peaks for each cylinder, a good idea.  Climb up to 8,000 ft to do it so you don't have to worry about detonation around the 50ROP danger zone.  Allow you to play around slowly with the mixture.  Keep an eye on redline egt of course.

    Scott

    -------- Original Message --------
    Subject: Re: REFLECTOR: Vortex generators location for armpit cooling scoops
    From: Brent mailto:bjb3013 at yahoo.com
    To: Velocity Aircraft Owners and Builders list mailto:reflector at tvbf.org
    Date: 08/14/2013 04:07 PM

      Have you tried a inflight LOP test and figure which cylinders peak when?
      How about swap the injector from your coolest cylinder to #5
      Not sure what VGs are going to accomplish if some cylinders are too cool already.

      Brent
      N61VB
      Std RG

      Sent from my iPad 5 

      On Aug 14, 2013, at 3:50 PM, "Andrew Ellzey" <ajlz72756 at yahoo.com> wrote:

        I am still battling a high CHT at cruse on my # 5 cylinder on my updraft IO-540-E1A5, 300HP Lycoming engine. I can do full power climb outs in the pattern all day without any issue. From everything that I have read on this subject on the Reflector, this is common with the arm pit cooling.  The higher pitch angle in the pattern, and in a cruse climb, forces plenty of cooling air into the scoops, but the cooling ability drops off in level cruse fight attitudes. My question is, is there anyone left on the reflector that is using the armpit cooling, and do you have vortex generators in front of your armpit scoops to help the airflow boundary layer adhesion to this area forward of the armpit scoops? If you have vortex generators, what size, location, did you make them, buy them, can you send a photo, please.

        I have swapped and calibrated my CHT probes, swapped the lowest CHT cylinder fuel injector with my #5 injector. Nothing helps, it seems to be tied with airflow into my scoops, or airflow inside my lower cowling. If the addition of vortex generators doesn’t  help, I will probably have to install some additional baffling to redirect more air to the aft two cylinders, #5, and #6. Cylinders 1, 2, 3, and 4 are getting plenty of air, in fact they are running cooler than I like at this time, but until I can get #5 CHT under control, I can’t lean my engine properly to know if I have adequate airflow for all cylinders or not. Installing my gear doors seemed to help.

        Photo attached showing my armpit cooling scoops. The additional screws under the armpit scoops, attaches a mating internal scoop that directs the airflow to my aft lower cowling.  

        Thanks again for your help,
        -----------------------------------------
        Andrew Ellzey
        N151AJ 10 hours into Phase 1 testing
        <DSCN7120a.jpg>
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