Australian Streamliner Bike Build

[kiwi belly tank]

I'm sure Jon is on the road to the salt by now so you guys can probably just keep crashing around in here for a while.
  Sid.

[Jon]

On the road , good to be out of town  
1800km down, only about 650 to go.

Can recommend the parking bay between Willcania and Broken Hill, can't recommend the steak at Cobar Caltex.

Countryside not looking too bad, a bit on the dry side but better than I thought it would be.


Cheers
jon

P.S. Highjack away, that's what it's for, we shan't be taking this thread too seriously.

I agree on eye and ear safety, it's not negotiable, a bit slack on welding jacket when tacking and fitting, shoes most of the time but can't do gloves much.

[manta22]

Hey Jon-- you're on the wrong side of the road! 

Regards, Neil  Tucson, AZ

[saltwheels262]

good luck on safe runs and weather.

[fastlammy]

Should be a fantastic drive Jon,talk lots of photos!

P.S looking at coming over your way in June for the winter Nat's

[tauruck]

That's a long way to drive. Holding thumbs for you Jon. Go well.

[kiwi belly tank]

This is one of those times that "a bit on the dry side" is desirable Mate.
You got wifi out back there?
  Sid.

[Jon]

Just about to loose mobile signal, 140km to go.

I brought some parts wash to share with you Grumm.

Back on line in 10 days.
jon

[gearheadeh]

Hey, must be some super POWERFULL car wash down there! 
Turned the hood of his car from blue to white   

Happy Motoring   

[kiwi belly tank]

Jeez that road looks pretty decent! I'm pickin thats north of Mt Ive.
  Sid.

[Heliophile]

Back on the yaw topic, if I may.  Many NACA and NASA reports are available at the NASA Technical Reports Server at URL  http://naca.larc.nasa.gov/search.jsp.  References useful at typical LSR speeds mostly date from WWII and earlier, before jet engines enabled higher Mach number speeds.  Several such reports are listed on my website, and I am sure that there are many more in the database.

A very readable report that is germane to this yaw discussion is Hoggard, H. P., "Wind-tunnel Investigation of Fuselage Stability in Yaw with Various Arrangements of Fins," NACA TN 785, 1940 (Document ID: 19930081581, Accession Number: 93R10871).  Jon is spot on with the assertion that hindering airflow over the top of the vehicle will counteract yaw.  This is likewise true of the bottom of the vehicle.  This report shows to what extent dorsal fins on the rear portion of the fuselage counteract yaw, which helps to choose fin location and height.  Fins on the forward portion of the fuselage destabilize the vehicle. 

I plan to use both dorsal and ventral fins on my streamliner, 2 to 3 inches high on most of the hear half of the body.  I am toying with the idea of adding side fins, to act as dorsal and ventral fins just in case it ever happen that I am sliding on my side hoping to remain pointed downrange.  I am told that it happens.   

Disclaimer: Always keep in mind that wind tunnel data taken from a model suspended in a test section is not necessarily directly valid for a wheeled ground vehicle.

Another interesting NASA article is
Benson, Tom, "Determining Center of Pressure," NASA model rocketry website http://exploration.grc.nasa.gov/education/rocket/rktcp.html.


I recently noticed that my polycarbonate eyeglass lenses have pits in them, even though I wear a face shield and ear muffs when grinding, and a helmet always when welding or riding a motorcycle.  I wear ear muffs for just about everything except listening to music and my wife, trying to save what little hearing is left after open pipes, guns, wailing amplifiers, and having an artillery simulator go off just as I came up out of a gully, back when I was young and foolish (I am no longer young).

[Jon]

Thanks Guys, back in civilisation, the isolation of Gairdner is one of the attractions.

Had a great time at Speedweek, met and hung out with a heap of people I've met via this site, too many to individually mention without my goldfish memory missing someone.

Was pit crew for DavieB, he had a pretty successful week, guess he will post up when he has some time.

Did a bit of time in bike tech giving Grumm a hand, was going to take a heap of photos, took very few, found myself busy the whole week.

Cheers
jon

[Jon]

Thanks Heliophile, I haven't read those two, will have a look.

On the keeping pointing downy rack when our bikes get tired is the main role of the chutes IMHO, slowing the bike on a good run is a bonus.
I tried 3 versions of mercury switches before I bought a solid state switch.

The roof and belly rail CFD runs are still coming, the naked front wheel has us heading in a better direction, now to get the back to behave some and it's CNC time for a body plug.

Cheers
jon

[Heliophile]

The chute is certainly the first choice for stabilizing a 2-wheel liner in a slide.  I have heard a few stories of chute failure, so side fins might be insurance, at the cost of a small increase in drag.  Just a thought, I haven't decided. 

[Heliophile]

Jon, I hope you don't mind if I hijack your site for a few minutes.  I have a question that I also posted under tech questions, but thought I might catch someone here who knows the answer.

The SCTA rulebook, motorcycle section, paragraph 7.H.13 Parachute, states that an automatic mechanism is required to actuate the parachute.  The laid over angle at which the system is required to actuate is different for closed tail liners (50 deg.) and open tail liners (80 deg.).

One obvious difference between the two configurations is that the drag coefficient may be somewhat larger for an open tail configuration.  However, I do not see that the drag coefficient should affect the lean angle at which the parachute deployment system is required to actuate.

I can still build my streamliner either way, but I am leaning (no pun intended) toward an open tail configuration because parachute deployment cannot be prevented by a door that fails to open. 

Why is the automatic actuation angle requirement different?

Is there some difference between open and closed tail design that I should be aware of?

Can anyone refer me to someone who may know more about this?