Extreme Flight 76/83" MXS

[3dNater]

Tom I am not an expert on this but I'll take a stab at it. Anyone that knows better feel free to chime in.

My understanding is that you need at least twice as much room for air to escape as what is coming in the front of the cowl for proper engine cooling. You can cut it all out of the cowl, or you could cut some out of the fuse if you are leaving the canister tunnel open. Lots of guys like to cut it all out of the cowl so they aren't putting air pressure on the inside of the covering and canopy.

I have seen some cool different options... like cutting diagonal slots so there are multiple exit holes like a grill. You can get creative to make it look good.

 

[AKfreak]

There is a boxed tunnel that runs a good length of the fuse. It's boxed off so no air can get in the fuse. I think I will make a plate there and use the diagonal crosses. Basislly all I need to do is measure the two round cowl opening, and double the surface area as an exit. That seems simple enough.

 

[Enterprise]

In my 78 with the VVRC-40 I cut out the last bay in the tunnel bottom for exit. Lighter than making a blocking plate.

 

[Ohio AV8TOR]

Yep 2-3 times the outlet area as inlet area. On my MXS I opened my tunnel. Exit air is good.

 

[AKfreak]

Yep 2-3 times the outlet area as inlet area. On my MXS I opened my tunnel. Exit air is good.

Can I see a pic of the bottom of your plane if it's not too much trouble.

 

[Ohio AV8TOR]

Can I see a pic of the bottom of your plane if it's not too much trouble.

I'll get a picture tonight when I get home from work.

 

[Ohio AV8TOR]

AK here is the bottom of my plane. If you do the math on the 3 inlets you will see that more is needed than just that lower cowl opening. I am going to wait until my VVRC40 is brok in and I have made this cover that I might put on over.

 

[AKfreak]

That cover is BA. Nice job! What did you make it out of, is that balsa sheeting with covering? That motor fits so much more nicely.

 

[Ohio AV8TOR]

That cover is BA. Nice job! What did you make it out of, is that balsa sheeting with covering?

No I made a cad file and printed it on our Objet machine. The material is more like plastic than wood and this weighed 26g I believe.

 

[vegasking]