Brodak 100 mile race PROP

[bob whitney]

  I see in the rules for the 100 mile race that either of the two Master Airscrew 8/6 's can be uses .the only problem is that they dont show the wide blade any more. so where dose that leave us guys that dont have a stock pile of these props . i have found one wide blade 8/6 if that happens to be the best prop . if it ends up being the best prop and i break it i am finished

[Motorman]

Just copy it in CF and paint it black with superpoxy.

MM

[bob whitney]

hdnt thought about  that,good idea

[Paul Smith]

No, no, CF, FG, etc are not allowed.  
It has to be the actual molded commercial product.  
The idea is to use something you can just buy.  Any of the black Master 8/6's are OK.  
If you scuff a blade and need to shorten it to make it balance, that's OK, too.

I'm getting my old racers patched up.  I'll be running engines as soon as it's above freezing here.  The weather is OK for working in the basement.

[bob whitney]

 that still dosent cure the problem of some having props that others cant get, i could use the carbon to practice with

[Charlie Johnson]

Tower Hobbies has the normal 8x6 Master Airscrew in stock for $1.59.  The Gray Scimitar Combat 8x6 is $1.99.  The 3-blade 8x6 prop is $6.19.
Tower offers a quantity discount and their free shipping offer may still be going.

[bill bischoff]

There are two different "normal" black Master Airscrew props. The "old" version has a noticeably wider chord than the current version. I think Bob is looking for the older wide blade props.

[bob whitney]

  that B the one

[Paul Smith]

We all gave up on the wide ones because the narrows revved up higher.
You can't always get what you want.
But if you try real hard you can get what you need.

[Brad LaPointe]

If this is a real problem I'll buy a dozen all the same , balance them and everyone will use "house" props . How's that for parity ? Spec racing for the masses .

Brad

[Paul Smith]

I'm sure there won't be a prop shortage.  Guys who win contests are able to get things a lot more scarce than Master Airscrew 8/6's.

What does Steve use?

[Motorman]

Bob, I think my LHS might have some of those original 8-6 props plus I'll look through my box. If I've got one it's yours. I think there were actually three versions made. I'll post up some pics if I find something.

MM

[bob whitney]

 Steve who??

contest winners dont let themselves get cought with the short end of the stick.

[Paul Smith]

Steve Stefanovic of Toronto, who wins every race unless some crash or mishap gets in his way.   Even with carefully equalized equipment he's still 3-8 MPH faster than everybody else.

[Paul Smith]

I checked the Tower catalog on line.  The specified prop, MA 0860, is available at $1.89 each.

[Paul Smith]

I copied the official MAAC Rules for LA 25 Sport Race.  

G.3.16 LA.25 Sport Race Rules

3.16.1 Purpose: It is the intent that this event will provide the competitor with a racing event which is low in cost, and fun to fly while providing a good training ground for those who wish to move on to more advanced forms of racing.
3.16.2 All pertinent M.A.A.C. racing rules shall apply in regards to safety and conduct of the races, except as follows:
2.1 Engine. The only allowable engine shall be a commercially available and absolutely stock OS Max LA .25 engine, operating on suction feed. (No chromed liners, or modified piston/liners will be allowed, and only the standard LA.25 venturi can be used.)
The only allowable modification is the replacement of the plastic backplate with a metal OS or Thunder Tiger replacement
It is recommended that all engines be checked before racing commences, and afterwards at the Contest Director’s discretion.
2.2 Aircraft. The model must be of profile fuselage type and have minimum fuselage length of 24 INCHES when measured from the face of the thrust washer to the leading edge of the moveable elevator.
2.3 Wing. The model must have a minimum wing area of 300 SQUARE INCHES and a minimum thickness of 1 INCH when measured at any point along the span with the exception of the last 5 INCHES before the wing tips.
2.4 The model must have a fixed landing gear with a minimum of one wheel not less than 2 INCHES in diameter.
2.5 The model may be equipped with a fuel shutoff system.

2.6 Fuel Tank. The fuel tank shall be fully external, mounted forward of the leading edge, and located on the outboard side of the fuselage. The tank may not be designed to cowl the engine. All vents are limited to 1 / 4 INCH outside diameter. The tank may not be pressurized but the vents may be directed into the airstream.
2.7 Propellers: Only stock black Master Airscrew 8 X 6 props will be allowed. (Only balancing and the removal of flash will be permitted.)
2.8 Fuel: Commercially available 10% Nitro Fuel will be used in official racing, and this will be supplied by the host club, at a nominal cost, in pre-designated containers.
(The fueling of models will be monitored by the race officials during the race. Immediate disqualification will be the penalty for any team that substitutes the official race fuel for their own.)
2.9 Glow plugs: Any standard glow plug that fits ¼ X 28 NF threads will be permitted. (Modified threads, or clamps will not be allowed.)
3.16.3 Prohibited Equipment: Pressure re-fuelers, hot–glove electrical contact systems, and centrifugal carburetor switches are prohibited.
3.16.4 Pull Test: The plane and control system shall undergo a pull test of not less than 25 pounds.
3.16.5 Lines: The minimum line diameter shall be .015 INCHES, and be of stranded construction with a length of 60 Feet plus or minus 6 INCHES when measured from the inside edge of the control handle to the centre–line of the airplane. Mono–line systems are not allowed.
3.16.6 Races: Preliminary heats shall be of 70-lap duration, with one pit stop required. Two preliminary heats shall be flown with the best result to count. Finals shall be of 140 laps duration, with three pit–stops required. All races shall be run with at least two, but not more than three entrants.
6.1 The start of a race shall begin with a two-minute warm-up period. During this period, the engine can be started and run right up to the commencement of the race. (The engines need not be shut - off prior to the start of the race). The starting signal shall be by flag, whistle or other highly audible or visual means. Once the signal to start has been given, the models can be released by the mechanics.
6.2 In the event that a competitor’s model completes the required number of laps in a race without completing the mandatory number of pit stops, he will then be timed until he completes the required pit – stop(s) and then flies one extra lap afterwards.
3.16.7 High Flying: The Contest Director may assess a penalty of two laps per infraction, and his penalty will be added to the length of a heat or final in which the penalty is awarded. Normal flying height will be between 10 and 25 FEET, except for passing.
3.16.8 Safety: All pitmen shall wear a hockey or motorcycle type helmet, which provides full coverage for the sides and rear of the head.
All pilots will fly without caps/hats to avoid the lines from catching on them. No water bottles will be allowed in the flying circle.

[Paul Smith]

The 100 Mile rules are the same with the following additions:

1400 laps with 20 pit stops.

You can use any spare equipment (airplane, engine, lines, pilot, mechanic) that you need to finish the race.

In the event of a two plane crash or tangle there will be a "red flag" stoppage to allow the circle to be cleared safely.

This event has been run in Toronto for ten years.  The system is well-proven.  Over 80% of those who start have been able to complete the 100 miles in under two hours.

[bill bischoff]

Where do you get a 1/4x28 glow plug? Or does everybody run illegal 1/4X32 glow plugs?

[Paul Smith]

I didn't write the rules.  What they're saying is: "use the normal screw-in glow plugs".

Not the big Nelson plugs.
Not the "turbo" plugs.
Not Cox/Rossi style glow heads.

Just plain ordinary plugs like Fox Standard Longs or K&B 1L's.  This is sort of double-redundant on top of "totally stock LA 25".

I'm glad to see you're interested.  Good luck in the race.

[bob whitney]

 i know i have seen it someplace but cant find it ,what is the legal size of the LA25 venturi ??

[Paul Smith]

The ones we buy from Tower Hobby, along with the OS 25 spray bar.  You're making this too hard.  It's just an off-the-shelf sport race.  You can order the engine, prop, venture and NVA for Tower.  Easy enough.

I bought a case of fuel from Randy Ritch.  I won't even charge for it.  Sealed one gallon jugs.

[john e. holliday]

Paul,  you won't believe this, but I had a venturi in one of my LA 25 that was bigger than the others I had bought from Tower.  I even checked the package.   

[Paul Smith]

Maybe so.  I've found that even with a fully-legal venturi and spray bar, the engine tends to balk off during acceleration with a light model.  So if somebody drills it out enough to matter, he probably won't get off the ground.  That's the intent of the outboard tank and suction fuel system. 

So if you can find two different stock venturis or two different black Master 8/6's, use the ones that work best for you.

[bob whitney]

Paul, i will be making my venturis as mine were both R/C  give me a hint ,what size should i be looking for

[don Burke]

Paul, i will be making my venturis as mine were both R/C  give me a hint ,what size should i be looking for

Bore for the 20/25LA venturi is 6mm.

IMO I would just order a couple from Tower Hobbies, they're about $10 ea, not worth the time and energy to machine one.

[bob whitney]

''sounds like the smart thing  to do

[bob whitney]

  found what looks like a stock LA venturi with an I.D. of .248, hope to break out an old slow rat and see how it go's with the LA 25

[Motorman]

Could not find the old wide blade 8-6 I was thinking of.


MM