erich weaver

erich weaver

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My baffle instructions do not indicate how far the air seal material should extend up above the baffles. Im guessing maybe a couple of inches? Dont want to be too short here.

Also, is there a downside to going with one continuous strip of seal material along each side and along the back rather than the multiple strips that my instructions show? I suppose a single strip would interfere with your ability to remove the baffles in the four quadrant pieces that they get assembled into, but it doesnt seem like the baffles would be removed very often anyway. Comments?

thanks,

erich weaver
 
I'd guess my baffle seal material sticks up 1.5" above the baffles.

The reason you can't use a single strip of baffle material is that your baffles will be trimmed to follow the profile of the cowl, which is a curve, not a straight line, particularly up close to the front. You need multiple pieces of baffle material so the material can fit the baffles properly and retain the shape and flexibility needed to seal against the cowl.
 
The baffle seals should be made in sections to allow them to lay flat under the cowl. The 90 deg corners would be very difficult to seal if you just bent the material around the corner. The seal should actually lay at right angles to the vertical AL baffle material. When air is blown in through the inlets, the seal rises up tight to the bottom side of the cowl to form the seal. There are many areas where several overlapping pieces of seal work together to form the seal. All the seal "lips" should lean in towards the incoming airflow. Then they can trap incoming air as they are forced up against the bottom of the cowl. Your vertical AL baffles should be trimmed to be about 3/8" from the bottom of the cowl. The rubber seals should be about 1 1/2" beyond the edge of the AL baffle, so cut them wide enough to allow attachment to the baffles.

Here is a picture of how the sections of seal are attached and pitched inward so they trap air. Rivet or lace the corners and curl the seals inward. When the cowl is placed on them, they form a loose fit until the pressure is created by incoming air. A slightly loose fit allows the engine to move about without damaging the cowl or baffles.

Hope this helps,

Roberta

oilcoolernw7.jpg
 
thanks for the replies kyle and roberta. A point of clarification: I didnt mean to imply that the seal material would be completely continuous - I recognize that separate strips are necessary at corners and where there are sharp curves along the top of the baffle. However, the instructions call for separate strips that overlap near the middle of both sides for example, where the left front side baffle overlaps with the left back side baffle). This area is pretty much a straight run from back to front - no significant curves along te top of the baffle pieces. I just dont see why the seal couldnt be continuous in this area, except possibly to allow future removal of the individual baffle components.

regards,

erich
 
Continuous Baffled Seals

Hi Erich,

I made the seal in three pieces (left/right/front). They fit and close perfectly. The trick is to bind or glue them temporarily together in the sharp aft corners so they bend inwards. Dan C promised me that they would settle in that position after some engine run hours (who am I to doubt him? :D ) You'll have to make a little contraption to bridge the oil cooler gap though.
See http://websites.expercraft.com/PHVII/index.php?q=log_entry&log_id=10081 and http://websites.expercraft.com/PHVII/index.php?q=log_entry&log_id=10438 for the recipe I used. If you are very careful you can get the patterns out of the sheet of rubber provided by Van's

good luck,
 
Cant get your web page links to work Rene - probably bogged down in Vans airforce traffic I guess.

YOu say your seals were in THREE parts? what happened to the seal on the aft bulkhead baffle parts?
 
Hi Erich,

Half of goes with the Left one, half of it goes with the Right one, simple as that. The 3rd one is the front one for the "around the prop-baffles" The pictures on my site should explain it all. If you can not get the links to work, please go via my web address, firewall forward, baffles. Or contact me offline so I can send you the pictures.

all the best,
 
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