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Landing Light in Cowl Inlet Question
http://t18.net/thorpforum/viewtopic.php?f=16&t=8704		 Page 1 of 1
Author:  Andy475 [ Tue Apr 26, 2022 10:37 pm ]
Post subject:  Landing Light in Cowl Inlet Question
My existing LED landing light set up on 78WG failed the other night on a dark moonless night. It had a Rigid Industries PAR 36 R+ which is a 2.5 inch light with a slotted 4.5 inch bezel. I can find the same replacement, but there's a significant wait. Additionally, I've never been a big fan of having the light in the inlet to begin with. Shopping around, I'd rather put a Whelen Parethemus G3 in, but that light fills the entire bezel. I'm concerned having this much of the inlet blocked by the light will cause a hot spot and lead to pre-mature failure of the cylinders. I've seen this happen on a 0-235 that had a homemade winterization kit installed.The kit cause hot spots on the cylinder wall leading to the wrist pin buttons heating up and failing. Any thoughts on what might be an acceptable amount of inlet blockage? I've considered moving the light elsewhere but would like to avoid modifying Walt's work to the max extent possible.

The Whelen
https://www.aircraftspruce.com/catalog/ ... kkey=22462

The Existing set up
https://overlander.com/products/rigid-i ... 0EQAvD_BwE

The current install setup
Image

V/r,
Andy
N78WG
Author:  James Grahn [ Wed Apr 27, 2022 11:15 am ]
Post subject:  Re: Landing Light in Cowl Inlet Question
So. This brings up an interesting question. We have a serial builder here at VGT. He has built 9 planes. On one, he was possessed with trying to get all his CHTs within 10 degrees. He made his own cowl, then modified it 7 times. During one of his tests, he actually tuft tested his engine compartment and videotaped it while flying. He, and the rest of us, we’re shocked at what it showed. In a nutshell, air entered the left intake (viewed from pilot seat) and exited the right. It was most pronounced during climb.
I’m not saying all intakes will do that. But it may be worth testing. I have a light in my right intake. I flew without it for a while and saw absolutely no change in CHTs. Data point.
Cubes
Author:  Ryan Allen [ Wed Apr 27, 2022 7:19 pm ]
Post subject:  Re: Landing Light in Cowl Inlet Question
I have the baja squadron lights (driving/spot combo) in both inlets. I am very happy with the lights. I see no change in CHT with them in or out.

https://www.bajadesigns.com/products/sq ... -pod-pair/
Author:  Andy475 [ Wed Apr 27, 2022 8:01 pm ]
Post subject:  Re: Landing Light in Cowl Inlet Question
Cubes,

Thats enough of a vote to inform a decision. I have a JPI where I can watch for serious fluctuations. The argument with the wrist pin buttons was that it actually wasn't recorded on the engine data recorder (JPI if I recall) because the temperature was measured at the head and not the localized hot spot... but this is also a speculative conclusion without any measured data to support it. I will say with that observation in mind, the Brits got it right with their inverted series engines and cowls...

-Andy
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