Zack wrote:From Sonex's webinar, they chose a similar setup but used a Toucan exhaust without a final merge, so it's really two 2-1 exhausts with a center line exit.
Zack wrote:Zack wrote:From Sonex's webinar, they chose a similar setup but used a Toucan exhaust without a final merge, so it's really two 2-1 exhausts with a center line exit.
Here's the video I was referring to: https://www.youtube.com/watch?v=OzNc-DfczJw&t=1s
However, I noticed when the one week wonder flew they chose a more direct approach out of the cowling. I wonder why they made the change.
[/quote][/quote]xeriotti wrote:My aproach on the cowling will be a little bit off plans... Im going for a more streamlined version, using the original cowling is out of the table.... has nothing to do with the 912 shape and lenght from firewall to the prop hub...
Zack wrote:I wish Sonex would be more public about their efforts to develop the Rotax firewall forward package. I think they made the decision to work within the current cowling early on and are constrained further by the tri gear option with the nose wheel firewall forward. Drawing air through a pair of stacked oil and coolant coolers using the two side vents doesn't seem adequate based on my poor analysis of other flying Rotax powered aircraft. Maybe Sonex thinks this will work due to the higher airspeeds this airframe has versus many other Rotax powered aircraft? This split design does avoid the space constraints of placing oil, coolant and nose wheel on the centerline, plus developing cowling "blisters" to accommodate the cooling. Perhaps running the exhaust to a single central exit by the firewall raises temps in the cowling too much? Easier and faster is also another good reason for the change!
Skippy, I worry if my cooling solution will work as well. I have a separate radiator duct that should be adequate. If it isn't, wow that's a major change to enlarge. I have two Sonex side vents to depressurize the cowling that had to be further opened to match the curvature of my cowling. The air moving through these vents will cool the oil cooler, air cooled parts of the engine, and remove exhaust waste heat. If Sonex is successful, then I will have more cooling drag than necessary.
Xeriotti, another reason the original cowling is out of the picture appears to be your spinner size! Are you doing a constant speed or ground adjustable propeller that needs the extra size? Regarding your exhaust exit, will you do a streamlined exhaust tunnel with the bottom of your cowling, or will the cowling be flush with the belly and the exhaust angled into the airflow?
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