Plenum design for the AFP Servo

[David_Nelson]

Originally Posted by David-aviator

David,

FWIT I wrestled with what you are doing for several weeks and could not create a plenum I thought was worth using. Seemed like the turn into the FM200 was too tight and too restricted in size, but it was never flow checked so it was just my opinion a result of it looking at it. It pitched the device a week or so ago as I got tired of seeing it.

Hi David,

I'd agree that the turn does seem rather sharp and would not work very well. Many moon's ago, I spoke w/ Don at AFP and he was kind enough to forward some pictures of various plenum installations similar to this. I also struggled with the "Should I go with the RAM air?" installation and what method - there's the 'Y' method, the Rod Bower (sp?) method, or something totally different. In the end, I figured that there's enough folks out there doing it with a plenum design and they seem to be working. I'm very curious as to how this design will flow and I'm sure others would be interested, also. Sometimes it feels that every little "diversion from plans" turns out to be not so little. At this stage, I'm trying to minimise those diversions and I _think_ this is the last one.

Originally Posted by David-aviator

David,
In the end (it was more work) I modified the cowl to accommodate the "Y" adaptor with straight in ram flow and a scat duct up to a filter at the left intake. The filter housing is home made out of aluminum. I know I suffer some take off performance with as the filter is a Brackett designed for the 172 but for now it works. Going to ram air after take off is noticeable as the engine surges up a hundred or so in rpm. What would be perfect is to figure a way to get a large K&N filter installed, an effort I may tackle some day. I have the proper angle ducting and the filter but have not figured a way to incorporate it into the left intake feature. It would work using internal air but that may be worse than with the Brackett filter using external air.

I can not say enough good stuff about direct ram air. The engine seems to really like it.

Right now, it's a "build the plenum" job and see how it performs. If the results from Don are average, I may just stick with that. If poor, then I'll take a step back and reconsider my options. Of course, I'm really hoping they'll be "good" so I can move on to the remaining 90% with a big grin on my face.

Take care,

/\/elson

[David_Nelson]

Hi Don,

Sorry for the confusion. Does this clear things up?



A little bit of the foam is wedged into the servo's opening to keep it in place. I've also made efforts to protect the internal parts of the servo from any foam FOD. It's my intention to prepare the foam and the servo's machined OD with mold release, etc and then glassing everything in place.

Thank you,

[Don at Airflow]

Looks good to me. Glass it up then send it to us. We'll flow it for you.

Don

[David_Nelson]

Will do. I'll give you a call to discuss details.

/\/elson