Other ways ot attaching AFP to the filtered air box

[David_Nelson]

Hi All,

This is on a 7A with a forward facing sump (IO-360-M1B) and an AFP FM-200
servo.

I'm at the phase of needing to connect the filtered air box to the AFP servo
via the VA-132-1 snorkel. I've done some searches and found some links to
folks that either 1) go the route of RAM air (ie. Robbie Attaway), 2) or
essentially cut off the end of the snorkel and reglass the portion that
connects to the AFP servo, or 3) somewhere in between. I've also looked at Rod
Bower's setup but it's a little out of my price range.

I am toying around with the idea of doing away with the lower half of the
snorkel and then using some 3.25" ID SCEET (1) tubing. My concerns with using
SCEET is that it is not recommended for negative pressure applications and I
can't find any data on preassure loses (especially around sharp bends).

Are there are any other options available? If you've got pictures or know of some links, I'd sure like to see/read them.

Notes:

1) SCEET: Aircraft Ducting "SCEET" type ducting has two plies of silicone
rubber impregnated fiberglass similar to SCAT except wire between plies. Sold
by the foot.

Features: Highly flexible and can be easily installed around obstructions and
sharp bends. Has less friction loss than similar non-lined ducting.

Applications: Ideal for use in conducting extremely cold or hot air at
temperatures ranging from -80?F to +550?F, and for conveying fumes. Not
recommended for applications involving liquids or highly abrasive materials, or
for negative pressure applications.

Thanks,
/\/elson

[andrew phillips]

here is what I did. I cut off the end of the fab where the flange is. I made an aluminum strip about 1/2" wide that I wrapped around the end of the servo like a collar. I drilled it for some flush rivets every inch or so then crimped them in. So now I have a collar around the servo with the shop heads sticking out all the way around (think spiked dog collar). I then opened up the end of the fiberglass FAB until it would slip over the collar. I made up a mix of flox and epoxy then embedded the ring into this mix while holding the fab in position. When the mix set up I removed the fab from the servo and then epoxied it until I got a nice smooth transition to the ring. so far so good with over 100 hrs. To hold the fab in place I fiberglassed in a small bracket that attaches to the alternator mount and also an embedded wire that has a loop at one end that goes under the servo attach bolts. Hope you can visualize what I am trying to describe.

[Mike S]

Originally Posted by David_Nelson

Hi All.

Are there are any other options available? If you've got pictures or know of some links, I'd sure like to see/read them.


Thanks,
/\/elson

Here is a totally different approach ------

[David_Nelson]

Originally Posted by andrew phillips

here is what I did. I cut off the end of the fab where the flange is. I made an aluminum strip about 1/2" wide that I wrapped around the end of the servo like a collar. I drilled it for some flush rivets every inch or so then crimped them in. So now I have a collar around the servo with the shop heads sticking out all the way around (think spiked dog collar). I then opened up the end of the fiberglass FAB until it would slip over the collar. I made up a mix of flox and epoxy then embedded the ring into this mix while holding the fab in position. When the mix set up I removed the fab from the servo and then epoxied it until I got a nice smooth transition to the ring. so far so good with over 100 hrs. To hold the fab in place I fiberglassed in a small bracket that attaches to the alternator mount and also an embedded wire that has a loop at one end that goes under the servo attach bolts. Hope you can visualize what I am trying to describe.

Hi Andrew,

Thanks for the very good description - no pictures needed. The only thing I'm having a problem visualizing is the aluminum collar. How did you keep it round while applying the flox? Did you just bend into submission so that it just held its own shape or something else?

Thanks,

[David_Nelson]

Originally Posted by Mike S

Here is a totally different approach ------

Hi Mike,

I must have forgotten about that thread. Thanks for pointing it out. It sure made me rethink Rod's system. One thing I'm not 100% clear on, if the butter fly valve is closed, is ram air just redirected through the filter or is 100% coming through the reed valves?

Thanks,
/\/elson

[Mike S]

Originally Posted by David_Nelson

One thing I'm not 100% clear on, if the butter fly valve is closed, is ram air just redirected through the filter or is 100% coming through the reed valves?

Thanks,
/\/elson

With the butterfly shut, the reed valves allow air to flow into the can, where it then goes through the filter. This is not ram air, it is ambient to the lower cowl. No ram air flow in this configuration.

When the butterfly is open, and you are at cruise, the air pressure forces the reed valves closed, and keeps the ram pressure in the intake system where it will do some good.

[David_Nelson]

Originally Posted by Mike S

With the butterfly shut, the reed valves allow air to flow into the can, where it then goes through the filter. This is not ram air, it is ambient to the lower cowl. No ram air flow in this configuration.

When the butterfly is open, and you are at cruise, the air pressure forces the reed valves closed, and keeps the ram pressure in the intake system where it will do some good.

Thanks for the clarification, Mike.