Ram air induction scoop design guide

[ggerhardt]

Hi folks,

I have a Velocity. I finished building it about a year and a half ago. Once I got all the bugs worked out, I've been working on performance improvements. One thing I'd like to look into is building a ram air induction scoop to get some increased MAP at cruise speeds. I've seen quite a lot of anecdotal information, but have yet to come across a good design guide that covers the various shapes, intake opening area, divergence angles and airbox volumes needed to properly take in high-velocity air and properly decelerate it to provide maximum pressure gain while minimizing drag.

If anyone knows of some good information to guide me on this, I'd appreciate it.

Thanks.

Geoff

[Ron Blum]

Highly recommend Kent Paser's book, "Speed with Economy". It's a good-sized paperback book that I believe is $30. It's real world and very good. - An Aerodynamicist.

[SheepdogRD]

Highly recommend Kent Paser's book, "Speed with Economy". It's a good-sized paperback book that I believe is $30. It's real world and very good. - An Aerodynamicist.

It's available from EAA for $24.95: http://www.shopeaa.com/speedwitheconomy.aspx

[Ron Blum]

It's available from EAA for $24.95: http://www.shopeaa.com/speedwitheconomy.aspx

Great find SheepdogRD. Thanks. Now this is what EAA is all about. BTW, he also does wonderful forums at OSH every year, too. :o)

[f1boss]

Hi folks,

I have a Velocity. I finished building it about a year and a half ago. Once I got all the bugs worked out, I've been working on performance improvements. One thing I'd like to look into is building a ram air induction scoop to get some increased MAP at cruise speeds. I've seen quite a lot of anecdotal information, but have yet to come across a good design guide that covers the various shapes, intake opening area, divergence angles and airbox volumes needed to properly take in high-velocity air and properly decelerate it to provide maximum pressure gain while minimizing drag.

If anyone knows of some good information to guide me on this, I'd appreciate it.

Thanks.

Geoff

Hey Geoff:

I see no genuine usable information yet. I don't recall Kent Paser doing any scoop work that mimics his other aero work - probably due to his use of a std carb, but I could be wrong. My suggestion would be to search the NACA archives to see how they did it way back when. I can tell you that if you get it right, your carb will not work right, and you will need to switch to FI. I can also tell you that if you already HAVE an FI system, it will also stop working as it does now, and will need mods - specifically an upper deck reference system. My email is f1boss at g-mail dot com for any further questions - I have made two systems that work, tho I can't see any reference to my 'style' of design in any reference material. I used the TLAR method, and it DID work: the better system puts out 31" *on takeoff* @ 600MSL. That specific plane has amazing high altitude cruise capabilities. See: https://flightaware.com/live/flight/N84MF and look for the higher altitude trips...

Carry on!
Mark