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Baffled by baffles

Blain

Well Known Member
I'm convinced if Vans sent baffle kits first instead of empennage there would be very few RV's in the air....

Looking at the transition of seal material from the forward section behind spinner to the inlet ramps. It is an abrupt step the looks like it would leave a void for air to leak.

How have others handled this area?
 
I trimmed the inside of the ramps to clear that vertical baffle by a bit. Then filled in the ramp on the inboard side to keep air from spilling through the ramp area. Then leaving the baffle quite tall in that area I attached fabric about half way down, just a narrow wiper strip that pressed up against the solid surface I glassed in to the side of the ramp area. It took two separate parts attached together at the corner to wrap around that area.

Cooling ramp close out by Andy Karmy, on Flickr

Setting the baffle height with paperclips by Andy Karmy, on Flickr

RV-8 FWF by Andy Karmy, on Flickr
 
No need to plug the ramps, if you do this right. The trick to the forward section of the baffles is to understand that the upper cowl ramps rest down on top of the baffle material to create the seal. Trim the ramps to where they are close to the baffles on both sides (~3/8" or so) and then form your baffle fabric curves to match the underside of the ramps. If you do this right, and in combination with the other pieces of baffle fabric involved (particularly on the lower cowl inlets), you will have it sealed pretty well.

There are a couple areas where Vans baffle instructions could be significantly improved, and this is one of them. It won't hurt to plug the ramps, but it's not needed.
 
Thanks for the visual, Andy. Last pic tells the story. Didn't consider moving the fabric down lower on the baffle.
 
No need to plug the ramps, if you do this right. The trick to the forward section of the baffles is to understand that the upper cowl ramps rest down on top of the baffle material to create the seal. Trim the ramps to where they are close to the baffles on both sides (~3/8" or so) and then form your baffle fabric curves to match the underside of the ramps. If you do this right, and in combination with the other pieces of baffle fabric involved (particularly on the lower cowl inlets), you will have it sealed pretty well.

There are a couple areas where Vans baffle instructions could be significantly improved, and this is one of them. It won't hurt to plug the ramps, but it's not needed.

I've seen a lot of builders extend their inlet ramps out beyond the side baffles, but per my RV-8 FWF plans circa 2006, my interpretation was that the upper cowl ramps are inside of the baffles (for both the parallel valve and angle valve engines). I built mine with the fiberglass ramps completely inside of the baffles and the baffles seals lay against the cowl and not the ramps. My ramps are open on both ends. I have excellent engine cooling with this arrangement.

Baffle%20Seal%202.png


IMG_0374%20%282%29.JPG


Skylor
RV-8
 
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I've seen a lot of builders extend their inlet ramps out beyond the side baffles, but per my RV-8 FWF plans circa 2006, my interpretation was that the upper cowl ramps are inside of the baffles (for both the parallel valve and angle valve engines). I built mine with the fiberglass ramps completely inside of the baffles and the baffles seals lay against the cowl and not the ramps. My ramps are open on both ends. I have excellent engine cooling with this arrangement.

Baffle%20Seal%202.png


IMG_0374%20%282%29.JPG


Skylor
RV-8

So the inlet ramp is narrower then the baffles, correct? And it looks like you used a reinforcement strip on the inside of the fabric. I considered that but wondered if it was overkill. Sure looks better.

Edit; OK, I re-read your post and I understand better now.
 
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Seal Reinforcement

So the inlet ramp is narrower then the baffles, correct? And it looks like you used a reinforcement strip on the inside of the fabric. I considered that but wondered if it was overkill. Sure looks better.

Edit; OK, I re-read your post and I understand better now.

Yes, I fabricated the doublers to rivet over the seals primarily so the seal material would lift between the rivets and cause air leakage.

skylor
 
Urethane paint?

So made a lot of progress once I got my head around what these baffles are supposed to look like. When it came to paint I thought I'd keep it simple and use the same paint as the interior. Matte finish, light gray urethane. Shot them yesterday and started cutting seals today. High quality with catalyst. Tuff stuff.

Feeling proud, looking good, then Oh, ****! Temperature!

Will urathane withstand the engine heat or am I going to be burning the paint off the baffles?
 
So made a lot of progress once I got my head around what these baffles are supposed to look like. When it came to paint I thought I'd keep it simple and use the same paint as the interior. Matte finish, light gray urethane. Shot them yesterday and started cutting seals today. High quality with catalyst. Tuff stuff.

Feeling proud, looking good, then Oh, ****! Temperature!

Will urathane withstand the engine heat or am I going to be burning the paint off the baffles?

My baffles are painted with Sherwin Williams Acry-glow acrylic urethane. No heat problems whatsoever in 530 hours.

Skylor
 
Puckers

You may get the puckers to flatten out if you cut a slit in the middle of each one. Cut back to where the pucker starts to form. The extra material should overlap where it is puckered now.


Don Broussard

RV 9 Rebuild in Progress
 
Drill out those four rivets starting at the spark plug. You can pull those puckers right out by pulling down. Cleco as you go forward and re-rivet.
 
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