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Author Topic: Question about the rule book  (Read 600 times)

Offline C.T. Schaefer

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Question about the rule book
« on: August 16, 2020, 04:53:15 PM »
I am busy working on a new profile ship so I can use a r/c throttle. It will be a new learning experience. It has been a while so I looked at the rule book on line and it prompted 2 questions.  First that the contest will provide fuel of 10% nitro. and then it says that IF that fuel was used then there are no mandated requirements for exhaust extensions.  This seems to be different than a few years ago. What does  'IF' mean?   Thanks, TS

PS  Not that it matters but I am still sore about the rule banning mufflers 45 or so years ago.

Offline Bob Heywood

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Re: Question about the rule book
« Reply #1 on: August 16, 2020, 06:38:27 PM »
If you run basically an open face exhaust or an extension no longer than 3 inches fuel is unrestricted.

If you run an engine with any sort of exhaust extension longer than 3 inches you must run 10% spec fuel supplied by the event director. In practical terms this applies mainly to the Nelson engine fitted with the Nelson tuned muffler.

The wording of the rule could stand to be improved.
"Clockwise Forever..."

Offline C.T. Schaefer

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Re: Question about the rule book
« Reply #2 on: August 17, 2020, 05:16:31 AM »
Thanks Bob, that's what I thought but it totally does not say that.  TS

Offline Paul Smith

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Re: Question about the rule book
« Reply #3 on: August 17, 2020, 07:12:49 AM »
I don't believe that mufflers or tuned pipes were ever banned.  It just said (in terms written by an amateur government lawyer) that if you used an exhaust extension over 3" you had to use 10% nitro.  So you can't have BOTH a pipe and high nitro at the same time. 

I have a plane with an exhaust pipe and I used my own 10%, unless the ED happens to have a house fuel, which is rare.
Paul Smith

Offline john vlna

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Re: Question about the rule book
« Reply #4 on: August 17, 2020, 10:31:43 AM »
mufflers 3 inches or less we allowed, but I think tuned pipes over that size were not until the 10% rule was passed. I used a long tuned pipe on a profile with 10% for a while. Fun but hard to get both high and low setup right. The Nelsons and tuned muffler made all that obsolete.

Offline C.T. Schaefer

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Re: Question about the rule book
« Reply #5 on: August 18, 2020, 05:53:49 AM »
Here is the history from my point of view. Around 1970 i wanted to fly Class ll and realized that my McCoy was not going to cut it. Everyone was using the beautiful Rossi .60 so I got an OPS!  It was a huge learning curve but in a couple of years I had it working pretty good. With the MO-1 the pipe ran under the wing so it was fairly unobtrusive. It was a little slow coming off the deck but in the air it was awesome. High speed times were equivalent to or a bit better than the Rossi's. I flew it at the '73 Nats and at the Cleveland meet once so it was seen around the country a bit.  Maybe some of you folks remember it?
  Previously to this there were no rules but people started thinking, and maybe they were correct, that, on most ships a pipe would spoil the appearance of the plane not to mention the more than incremental increased speed potential. So, they made a rule of no mufflers of any kind and that stuck for many years until they came up with the current rules.  I sulked for a few years but eventually converted the OPS to run open face and built a new plane. It still held it's own against the Rossi .65's of the day.  All in all, good memories!   TS

Offline Paul Smith

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Re: Question about the rule book
« Reply #6 on: August 18, 2020, 11:48:01 AM »
From what I remember, back in the day, they just cut through whatever was in the way, as in this Wallack Class I with the pipe through the canopy.

The original US Navy carrier event allowed ANYTHING under four pounds with NO power limitation of any kind.  They even INVITED jets.  The ultimate model of the unlimited days was the Randel Tigercat with .72 worth of Johnsons.
Paul Smith

Offline Ron Duly

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Re: Question about the rule book
« Reply #7 on: September 19, 2020, 12:16:39 PM »
The Tigercat used 29 and 35 Johnsons for a total of .64.  The 29 was on the outboard side with with a 3/4 oz. tank so it only ran on the high end.  This lead to a rule change to require both engines to run during the entire flight.


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