Arnold rule; Mike Arnold's aerodynamic ideas

[Max Volume]

Mike and I talked a lot about this when he was writing this article in Sport Aviation. Sorry I had to borrow so much from our older movies - and everybody else - REMEMBER! - "Area Rule for supersonic - Arnold Rule for subsonic"   

 

[djpacro]

Great stuff.

[rgmwa]

Found this: 

 

 

185 kts using a 65hp Rotax 582 is pretty good.

[Thruster88]

Interesting to see the exhaust early in the vid. Looked stock Rotax,  no dual expansion chambers. The exhaust was wrapped maybe to minimise cooling drag and maximise exhaust thrust, every bit helps. The 582 tuned up could produce 100hp given it's displacement. 

Edited February 9 by Thruster88

[Max Volume]

Mike had to alter the shape of the exhaust to fit inside the cowling, so the engine wasn't even getting the stock 65 H.P.!!

[Red]

10 hours ago, Thruster88 said:

Interesting to see the exhaust early in the vid. Looked stock Rotax,  no dual expansion chambers. The exhaust was wrapped maybe to minimise cooling drag and maximise exhaust thrust, every bit helps. The 582 tuned up could produce 100hp given it's displacement. 

Exhaust wrapping has nothing to do with cooling drag, it simply keeps exhaust gases hotter which may increase engine efficiency, its rather complex but I suspect the wrap in this instance is simply to stop burning the closely fitting cowl.

Cooling drag is all about the reducing the drag from the airflow that is used to cool the engine, in other words careful design of inlets, outlets and the flow between these points. theoretically cooling drag can be reduced to a negative figure I.E. thrust.

[peterg]

20 hours ago, Max Volume said:

Arnold Rule for subsonic

A very good video - thanks for that.

 

A recent, visible example is the "tidying up" of the Foxbat to produce the Vixxen

 

[Max Volume]

Thank you Red! I knew about cooling drag but not about exhaust heat. Mike never told me anything about it so I suspect he wasn't thinking about it. Here's part 1 of his visit with Alex Strojnik;  

 

[T510]

Thanks for sharing the video, a great watch

[Red]

Yes, I've watched some Videos on Arnold's design a long time ago but there is new stuff (to me) here Thanks Max

[Max Volume]

Here's #2;  

 

[Max Volume]

- canopy, exhaust stub and laminar flow are discussed - Alex visited Crockett in 1993 and this movie just never got made. Mike isn't here to edit it down so I left it largely unedited because I really don't know which part any one person might want to see - more to come! Please let me know how you like it in the comments...    

 

[Max Volume]

 

[Max Volume]

Mike Arnold visits Dennis Sanders and Dreadnought pt1;   

 

[facthunter]

Some good stuff there.  Nev

[Litespeed]

I spent many nights pondering and playing with designs to do a updated AR5. It is a lovely design.

 

I played with basically a Carbon version for reduced weight and increased 'G',  trying more advanced airfoils etc trying to get a better low speed handling. 

 

The ace in the hole was using a 110 hp Simononi  from Italy, instead of the 65hp rotax, the extra 45 ponies would make a substantial dent on the FAI 300kg world record.  

 

If I won lottery...

[Max Volume]

Mike Arnold's AR-5 up close...   a slideshow from stills I took when we delivered the world record breaking (officially 213.18 M.P.H.) AR-5 to the Hiller Air Museum in San Carlos, Ca. on April 9th 2001 (where it still resides-)  

 

[Max Volume]

Mike Arnold visits Dennis Sanders pt2    

 

[Max Volume]

a short clip I found - no real punchline, but an interesting look at the AR-6 at that stage -