Motorcycle streamliner parachute auto-deployment system.

[Heliophile]

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. 

Does anyone know why the automatic actuation angle requirement is different?

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

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

[dw230]

What did the motorcycle tech people listed in section 16 of your rulebook say?

DW

[grumm441]

It may be that with the closed tail they want to get the chute out before the bike is on it's side and the chute doors are being held closed by the vehicle laying on it's side
G

[Dean Los Angeles]

Tip your liner over to either of the required activation angles and ask yourself "I've already crashed, haven't I?" You could certainly trigger at less of an angle.

I'll pose the question to the streamliner guys. What angle do you consider to be non-recoverable? At what perceived angle from the cockpit would you pull the chutes.

Don Vesco was the master at streamliners and was considered "quick with the laundry".

[Jon]

My wheel fairings will start to touch down at 20 degrees, I think i have no chance of recovery from there.
I'm initially setting my tilt switch at 40 degrees, thinking of running a second one at a tighter angle with a latching circuit while i do slow runs teaching myself to ride to see how vibration effects it.
Ideally I'd like to run the tilt switch at 25 degrees if it doesn't false trigger.
It''s solid state and made for earthmoving machinery, vibration shouldn't worry it hopefully.

See my build diary post from a couple days ago for my thoughts on mercury switches.

jon

[Heliophile]

What did the motorcycle tech people listed in section 16 of your rulebook say?
DW

DW, you make a good point.  The SCTA storehouse of LSR knowledge is always a good place to mine for guidance.  The responses have  improved my build, especially safety-wise.  I hesitate a bit to bother these guys too much, as they are volunteers donating their time, but they always insist that I am not being a pest. 

The answer this time was that it was, to the best of recollection, most likely a "can you get the doors open" issue that dated from the very early 90's.  I posted the question here to get a discussion going and to hopefully get additional ideas and information.  That worked.  S-cubed is a prince for providing this forum.  Which reminds me, I need to make a donation to support it.

I have on a number of occasions been a bit frustrated by the SCTA rule book.  The rules are generally presented quite clearly, but the reason behind a rule is seldom given and is often not obvious.  Such explanation would help builders, especially we newbies, to go a little further in the right direction, which is always a good idea IMHO when it comes to safety.  Also, it would help to avoid loss of accumulated expertise as time goes on.  There are admittedly probably valid reasons for not doing so.

LP

LP

[dw230]

Out of curiosity, do other association rulebooks, NHRA, NASCAR, HAMB, FIA, etc. provide a history of the rules written in the book?

DW

[grumm441]

Out of curiosity, do other association rulebooks, NHRA, NASCAR, HAMB, FIA, etc. provide a history of the rules written in the book?

DW

It wouldn't fit in my pocket anymore.
G

[Tman]

Larry, you could put a moisture sensor in your shorts that  deployed the chute at the first sense of....................nevermind

[Dean Los Angeles]

Larry, you could put a moisture sensor in your shorts that  deployed the chute at the first sense of....................nevermind

The latency of the squirt detector takes to long. The pucker factor pressure sensor is MUCH faster.

[Tman]

Larry, you could put a moisture sensor in your shorts that  deployed the chute at the first sense of....................nevermind

The latency of the squirt detector takes to long. The pucker factor pressure sensor is MUCH faster.

Yeah, I was thinking of a pressure sensor for that!

[Heliophile]