Fluid Dynamics of Drag

[LuckyDuc]

I found this video about Fluid Dynamics of Drag and thought I would share. I posted it on IW and thought I should post it here too. Very interesting stuff. It makes me consider putting an air foil around my rigger's boom tubes.

[Fluid]

It's been done. The German JAGs team used streamlined booms on some of their SAW riggers in 2004. The top photo shows they used carbon fiber booms. Tim Higdon took these a step further in 2006 with his record-setting riggers as seen in the second photo . Tim used balsa fairings over round carbon booms, but he found they had two problems. First they were fragile and unlike the German application would not survive a crash. Second, once the rigger got out of shape they acted as lifting surfaces and helped the rigger blow off. In the second photo the aft boom fairings are already lost and the right front has been replaced.

The idea is good but reducing boom cross area is probably a better goal for most FE uses.






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[detox]

That opens the door for more ideas. Thanks for sharing.


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[NativePaul]

I cant see the pictures Jay, would like to though.

[LuckyDuc]

I was thinking about using these streamlined aluminum tubes that you slide/ glue over your existing boom tubes.

K&S makes them for airplane struts: http://www3.towerhobbies.com/cgi-bin...?&I=LXR857&P=7

They make it in 1/4, 5/16, 3/8, 1/2, 5/8, and 3/4" by 35" long

[sundog]

I wonder what a wedge rudder would score? I have a rigger with a wedge rudder that I thought was too wide, so I rounded the rear off in an effort to reduce drag. I now see that was a mistake.

[Gary]

Sundog that was a mistake that I learned a long time ago. You want the rudder to have a perfect FLAT back side and bottom. I will try and find the article for you on rudders. Its a good read.

[sundog]

Sundog that was a mistake that I learned a long time ago. You want the rudder to have a perfect FLAT back side and bottom. I will try and find the article for you on rudders. Its a good read.

Gary, I think I found it. It stated that the flat area behind the rudder draws in and holds air (bubble), which directs the waterflow on both sides of the rudder to converge at a point well behind the rudder, thus eliminating (or at least reducing to a great extent) any drag. Sound right?

[Fluid]

I cant see the pictures Jay, would like to though.

It seems most can see them. I'll try a different way in this post and see if that helps you.

[befu]

If you ever get a chance to play with a decent wind tunnel, you will see a lot of neat things on riggers and tunnels. Had access to one at western Michigan univ. back in the late 80's, early 90's. Many experiments done and it is surprising what the forces are on some of our designs.

I also find it interesting what others take from these videos and the tidbits they speak up about. Some people see them differently and apply it differently.

Good stuff. Brian

[HOTWATER]

This was done when they made the Prather Spitfire's. For those that do not know this boat, there are round aluminum tubes inside the epoxy formed booms going from one sponson, straight through the tub to the other sponson (strong). Was fast as a nitro...now i'm gonna find out what it will do as an FE O/B rigger!!

[LuckyDuc]

This was done when they made the Prather Spitfire's. For those that do not know this boat, there are round aluminum tubes inside the epoxy formed booms going from one sponson, straight through the tub to the other sponson (strong). Was fast as a nitro...now i'm gonna find out what it will do as an FE O/B rigger!!

Nice piece of history you have there!

[HOTWATER]

Thanks! I bought this back around '92 or so. I'm very curious about what this rigger can do with some amps!! It even has a rear ride pad just like the JAE....

[Diegoboy]

This video is still interesting to me...