Q-500 Carb/Shutoff rules  
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All Forums >> RC Airplanes >> Pylon Universe - RC Pylon Racing >> Q-500 Racing >> Q-500 Carb/Shutoff rules
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Q-500 Carb/Shutoff rules - 4/13/2002 10:00:45 AM   
Scorpionjack



Posts: 656
Joined: 12/3/2001
From: Minot, ND, USA
Status: offline 		Ok just a question! The rules stipulate we must have carbs. So we have a Carb set to max Open throttle and locked to this position. What if we install a pinch shut-off as we had on F-1's. Is this legal? Maybe I missed it in the rules but did they take out Operational carb, from the rules for Q-500?

I may have missed it. but I could swear years ago it had to be operational by the rules. Now I don't see it anymore.
       Post #: 1

Q-500 Carb/Shutoff rules - 4/13/2002 11:23:43 AM   
PylonWorld



Posts: 1346
Joined: 12/29/2001
From: Monroe, NC, USA
Status: offline 		Jack,

I looked at the 1999-2001 rules and they don't mention a locked position carb, however, the changes that went into effect on 1/1/2000 do have the new wording.

So that seems to mean a proposal was passed that allowed for the locked carb, or else acceptance of the urgent rules change for 1/1/2000 allows for it.

The 1/1/2000 rules were the re-write into a modular form. You can see them [URL=http://www.modelaircraft.org/Comp/1999Pylongurgent.htm]here[/URL].

I have the PDF for the 1999-2001 rules if you want it. The word "locked" doesn't even appear in them.

I had noticed it in the 1/1/2000 rules, but I didn't see the utility in it. But, if you use a tank in a CG or near CG position, there's plenty of room for an internal kinker, and you don't have to have any throttle linkage out front. And if you don't have to have throttle linkage, then why would you need an arm to turn the carb/air valve? Hmmmmm. No hemostats or inline fuel shutoff clips to deal with ...

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RCPRO Chairman of the Board

(in reply to Scorpionjack)
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Q-500 Carb/Shutoff rules - 4/13/2002 5:09:03 PM   
Scorpionjack



Posts: 656
Joined: 12/3/2001
From: Minot, ND, USA
Status: offline 		Ditto! Don my point exactly

(in reply to Scorpionjack)
       Post #: 3

Q-500 Carb/Shutoff rules - 4/13/2002 6:36:09 PM   
Ed Smith


 

Posts: 2853
Joined: 12/29/2001
From: Brantford, ON, CANADA
Status: offline 		Jack,

Here is the rule that answers your question.

3. Intake. A single carburetor with a maximum inner diameter of 9 mm(0.3543 inch.). The carburetor may be locked or pinned in the open position and need not be functional; except that if the carburetor is not functional, a seperate engine shutoff mechanism shall be used. Other than such locking or pinning the carburetor shall be stock. Venturis are prohibited.

We all know now what Henry Nelson did with that rule.

The rule as worded does not make sense. The definition of a Carburetor in the rule is wide open. A carburetor is a device for mixing air and fuel. It has very little to do with a throttle mechanism which is not mentioned at all. The air and fuel is mixed at the spray bar hole down in the tube. I could remove all of the black plastic above the spray bar hole and claim that my carb is locked in the open position by the spray bar.

However I will leave it alone.

Ed S

Ed S

< Message edited by Ed Smith -- Apr 13 2002 1:47PM >

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       Post #: 4

Venturi, Not carb - 4/20/2002 10:00:01 AM   
Bill Vargas



Posts: 1570
Joined: 1/6/2002
From: Team Coldies, CA, USA
Status: offline 		[QUOTE]Originally posted by Ed Smith
Jack,

Here is the rule that answers your question.

3. Intake. A single carburetor with a maximum inner diameter of 9 mm(0.3543 inch.). The carburetor may be locked or pinned in the open position and need not be functional; except that if the carburetor is not functional, a seperate engine shutoff mechanism shall be used. Other than such locking or pinning the carburetor shall be stock. Venturis are prohibited.

We all know now what Henry Nelson did with that rule.

The rule as worded does not make sense. The definition of a Carburetor in the rule is wide open. A carburetor is a device for mixing air and fuel. It has very little to do with a throttle mechanism which is not mentioned at all. The air and fuel is mixed at the spray bar hole down in the tube. I could remove all of the black plastic above the spray bar hole and claim that my carb is locked in the open position by the spray bar.

However I will leave it alone.

Ed S

Ed S [/QUOTE]

Hey Ed, go ahead and remove the black plastic and lets see how it runs,,, you still owe me a Junk War Race

BV

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(in reply to Scorpionjack)
       Post #: 5

Carb/Venturi/Rules - 4/20/2002 4:50:41 PM   
Ed Smith


 

Posts: 2853
Joined: 12/29/2001
From: Brantford, ON, CANADA
Status: offline 		Hi Bill,


>>>Hey Ed, go ahead and remove the black plastic and lets see how it runs,,, <<<


Funny you should say that. When the Q40 engine first came to market it had the backplate mount and the short spinner backplate. It was a real nightmare installing the firewall. It was also almost impossible to remove the engine from the airplane with everything so tight. In most cases one had to remove the venturi, which meant removing the spraybar. In any case clearance for the venturi meant grinding away the fuselage right up to the nose ring. Most nose rings split after a while.

To remedy this nuisance my flying partner at the time cut his venturi off. All that remained of it was about 1/16" above the 'o' ring, just enough to to create a shoulder to hold the 'o' ring in place. He had to keep some plastic in there to maintain the 9mm I.D. This lack of trumpet shape made no difference whatsoever to the running of that engine. In fact why should it? Nelsons rear intake engines do not have a venturi, just a great big pie shaped hole. This would indicate that the trumpet shape is cosmetic only. Many people remark about the huge venturi when they see a Q40 engine. Very few say the same about the 428 engine. Yet they both have the same size hole 9mm.

So, you will excuse me when I smiled (Just a little) at your super sized speed secret. suck it all in venturi. It sure looked impressive though.

Ed S

(in reply to Scorpionjack)
       Post #: 6

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