belly radiator

[dholly 718]

Oh, I dunno Ed. As you noted, this would be an adviseable and easy upgrade to do during an early KF build/re-build. Something tells me Tjay is already aware of the push/pull tube end and elevator weldment differences, I'm guessing he is fitting a larger elevator which requires the Heim end. Hope the pics helped Tjay.

[EDMO 1078]

Mine is an "early build / rebuild" - Only started 18 years ago, 3 other planes, and then restarted 6 years ago!

Now waiting on Avid Magnum boot cowl, firewall, flaps and ailerons, elevator rod ends and wing struts.

EDMO

Edited 19 Mar 2015 by Ed In Missouri

[TJay 1041]

pictures always help thanks, and for the rod ends i am using the ones that you sold me off that kf 3 thanks guys,

Edited 19 Mar 2015 by TJay

[Av8r3400 1179]

Elevator fork, Kitfox IV (Mangy Fox).

 

 

[dav8or 20]

I went through the belly radiator swap on my Avid last year. I ended up with the radiator a little more than an inch below the fuselage due to the way it was mounted. First problem for most Avids on the belly mount is the lip at the bottom of the cowling. I am sure it was there to create a better low pressure area at the cowling exit but it also deflects air passing by the outside of the cowling and forces it somewhere below the radiator. The other problem is the heat from the muffler/exhaust which exits the cowling and passes straight through the new belly mounted radiator. The Kitfox may have a different setup. I have not seen one up close so I can't compare. I solved both problems at once but removing the lip and fabricating an aluminum pan that both helps the outside air stay attached to the bottom of the fuselage and pan until it passes through the radiator. The pan also keeps the exhaust heat from passing directly through the radiator and instead passes it over the top of the radiator through the gap between fuselage bottom. Exhaust heat is also allowed to spill off the sides of the pan out away from the radiator.

 

The pan is fastened the the lower edge of the cowling and lays on top of the radiator. There are also 2 aluminum bracts riveted between the pan and firewall to keep it in place. I folded the sides of the pan down with plans to make a scoop to go over this but may be changing cowling so have stopped development on that.

 

With this setup most recently with OAT around 70 F I had to tape almost half of the radiator off to get temps above 130. I currently do not have a thermostat installed but plan to put it back in. I have flown with this set up in the 90+ degree weather we get down here in South Texas last summer and never had the water temp get above 160 (that was with thermostat).

 

Hope this might help a little.

 

Dan

[1avidflyer 1983]

I would be leary of running without a thermostat. To easy to have a cold seizure with out a thermostat in place in my opinion. Also helps to keep engine from cooling to much in a descent. Last Avid I bought was run like this, and I had to bore it out and install new pistons. Jim Chuk

[dav8or 20]

I plan to put it back but that was the first thing I pulled out when I overheated on a flight a couple of months ago. One moment the temp was at its normal 150-160 and the next time I look down it was showing close to 220. The following 10 minutes after that were very anxious with throttle reduction as the first move which brought the temp down and also put me in a 700 fpm descent. I picked out a rough sand road crossing the Intracoastal pasture below me as my landing spot while I tried increasing throttle as much as I could until the water temp was a little over 190. That was just enough throttle to barely maintain altitude which after the descent was 1500'. I debated landing out and risking damage or flying the 7 miles to make it back to the field. After a couple of minutes of maintaining level with a stabilized temp I decide to go for the runway and made it but it was a tense few minutes of flying over an area with few good places to attempt an emergency landing.

 

I have tested that thermostat in a pan on the stove and it appears to operate properly but had scraping marks on one side. I was not sure if it was the thermostat or the air bubble issue that we noticed while testing after that was the cause of the overheat so the thermostat has been out since then. I will install a new one soon.

 

Dan