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Author Topic: Brodak fuel use  (Read 2989 times)

Offline Clint Ormosen

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Brodak fuel use
« on: November 09, 2007, 02:07:24 AM »
I'm almost finished with a Sig Mustang that I had planned on putting an OS 35-S into. I switched to the Brodak 40 but there is not enough length in the nose of the plane to install a 4 1/2 oz tank. Can you get a Brodak 40 through the pattern on a 4 oz tank if I use 5% fuel. I already know it won't make it on 10% fuel.
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steven yampolsky

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Re: Brodak fuel use
« Reply #1 on: November 09, 2007, 05:29:48 AM »
Quote from: Clint Ormosen on November 09, 2007, 02:07:24 AM
I'm almost finished with a Sig Mustang that I had planned on putting an OS 35-S into. I switched to the Brodak 40 but there is not enough length in the nose of the plane to install a 4 1/2 oz tank. Can you get a Brodak 40 through the pattern on a 4 oz tank if I use 5% fuel. I already know it won't make it on 10% fuel.

After they've been broken in, the fuel consumption is about 3.25-3.5 oz. I use 10% SIG fuel(20%oil) with 1oz of Randy's Aero-1 additive.

EDIT: Forgot to mention. Break in is 10 2min runs on a stand and ~30 flights. Fuel economy begins to improve after about 15 flights.
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Offline Ralph Wenzel (d)

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Re: Brodak fuel use
« Reply #2 on: November 09, 2007, 06:06:00 AM »
Steven is about right concerning breakin. As the engine wears in, you will notice a very slow increase in fuel economy, and power, as well. There will come a point (at least for mine) where abruptly I had to turn the needle in 2-2½ turns to maintain rpm/power. This is where the engine is almost truly broken in. Small additional improvement will be noticed.

Prop and fuel selection also play a significant part in fuel economy and overall engine performance. Mine seemed to run best on a Rev-Up 12-5 cut to 10½" diameter. I have not yet tried the new RSM 11-5 prop, but it should be excellent.

I used PowerMaster GMA 10-22 fuel throughout. I'm certain economy would improve with the 5-22 blend.
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Offline Bob Zambelli

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Re: Brodak fuel use
« Reply #3 on: November 09, 2007, 07:52:34 AM »
Good call about fuel. I have been using Powermaster 10/22 in all my engines untill last year when I switched to Brodak 10/23. Both fuels are excellent.  y1 y1

Yes, I even run the same fuel in my Fox .35s and vintage glow engines.  ~^

I still have the very first Brodak .40 and although having countless hours on it, it still holds perfect compression and runs like new.

Also correct about fuel economy - it will continue to improve as the engine builds time.

In some of the smaller 4S engines, the economy will near double once the engine is fully run in. One of my SAITO .30s required nearly 3 1/2 ounces when new and now needs less than 2 ounces for the pattern.

Bob Z.
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Offline Bill Little

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Re: Brodak fuel use
« Reply #4 on: November 10, 2007, 03:58:55 PM »
Quote from: Clint Ormosen on November 09, 2007, 02:07:24 AM
I'm almost finished with a Sig Mustang that I had planned on putting an OS 35-S into. I switched to the Brodak 40 but there is not enough length in the nose of the plane to install a 4 1/2 oz tank. Can you get a Brodak 40 through the pattern on a 4 oz tank if I use 5% fuel. I already know it won't make it on 10% fuel.

I made a tank to fit in the compartment and holds about 4 1/4 oz.  The Sig Mustang has very little tank compartment.  A normal 3 1/2 oz. tank is about all that will fit.

Bill <><
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Big Bear <><

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Offline Clint Ormosen

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Re: Brodak fuel use
« Reply #5 on: November 12, 2007, 01:47:49 AM »
Quote from: Bill Little on November 10, 2007, 03:58:55 PM
I made a tank to fit in the compartment and holds about 4 1/4 oz.  The Sig Mustang has very little tank compartment.  A normal 3 1/2 oz. tank is about all that will fit.

Bill <><

Bill, since I modified the tank area to use a slide in tank, a 4 oz fits okay. But a 4 1/2 oz is out of the question. The tubes hit the backplate of the motor.
A friend of mine is flying a well broke in Brodak that will not do the pattern on 4 ozs of 10/22 fuel. He had to go to a bigger tank and is using about 4 1/4 oz to complete the pattern.
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steven yampolsky

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Re: Brodak fuel use
« Reply #6 on: November 12, 2007, 05:50:46 AM »
Quote from: Clint Ormosen on November 12, 2007, 01:47:49 AM
A friend of mine is flying a well broke in Brodak that will not do the pattern on 4 ozs of 10/22 fuel. He had to go to a bigger tank and is using about 4 1/4 oz to complete the pattern.

Can you provide some details? I am curious why there's such a difference. What kind of prop is he flying? model size,weight, lap times. What about the bearings? Does the crankshaft feel loose in there?

Both of my B40's use less than 4oz and so do about half a dozen B40's of people in the area.

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Offline Jim Oliver

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Re: Brodak fuel use
« Reply #7 on: November 12, 2007, 07:01:38 AM »
Locally, we use 4 oz. of 10/22 for the B40, but we mostly run the Zinger Pro 11x5 at 8800-9000.  A lower pitch prop at higher rpm means that a fuel charge goes into the engine many more times per minute.  Could account for slightly more fuel usage, maybe------or not. ???

Jim
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steven yampolsky

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Re: Brodak fuel use
« Reply #8 on: November 12, 2007, 11:41:15 AM »
Quote from: Jim Oliver on November 12, 2007, 07:01:38 AM
A lower pitch prop at higher rpm means that a fuel charge goes into the engine many more times per minute.

Hmm, I would think otherwise:
1) To get higher RPM's, one has to close the needle, decreasing amount of fuel delivered.
2) Runaway engines tend to run longer.


Quote from: Jim Oliver on November 12, 2007, 07:01:38 AM
we use 4 oz. of 10/22 for the B40, but we mostly run the Zinger Pro 11x5 at 8800-9000.

Here's another oddity that puzzles me. I run 11x4.5 at 10,000 and 3.25oz per flight. When compared to the setup listed, fuel consumption should have increased by 10%(~.33oz), not 23%(.75oz).

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Offline Jim Oliver

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Re: Brodak fuel use
« Reply #9 on: November 12, 2007, 06:13:12 PM »
Steve,
Actually, the lower pitch prop will spin faster at the same needle setting, thus my comment about increased fuel usage.  Don't know if usage really goes up though.  I have not yet tried the APC 10.5x4.5 that some guys like so much.  Just wondering out loud---------- n~

Jim
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Offline Clint Ormosen

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Re: Brodak fuel use
« Reply #10 on: November 15, 2007, 04:46:10 AM »
Quote from: Steven Yampolsky on November 12, 2007, 05:50:46 AM
Can you provide some details? I am curious why there's such a difference. What kind of prop is he flying? model size,weight, lap times. What about the bearings? Does the crankshaft feel loose in there?

Both of my B40's use less than 4oz and so do about half a dozen B40's of people in the area.



The current setup is a MA 10-5 three blade on a 38 special. I don't know the weight but if I had to guess I'd say about 37-38 oz. I couldn't say about the bearings either, but the engine doesn't have so much time on it they should worn out. Lap times are about 5.2-5.3. launch RPM at 9800. Fuel use was about the same with a BY-O 10-5 prop.
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Offline Bill Little

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Re: Brodak fuel use
« Reply #11 on: November 16, 2007, 09:03:07 AM »
Hi Clint,

As we both know, there are many, many variables that affect fuel consumption.  Density altitude, individual fits in each engine, rpm, and so forth.

If the engine is producing adequate power, you like the style of run, and all else is acceptable, you can use the *pantyhose* trick to get a touch more fuel milage.  Otherwise, I would just find a way to get more fuel in the plane.  I have a set of tables, somewhere, that I got from Charlie Reeves that lists dimensions for different styles of tanks that will hold "X" capacity of fuel.  Mr. Al Rabe has always concocted special shape tanks for his Scale Stunters, and they work great.  A mesage to Al giving the specs of the engine compartment area might be worth a shot. 

The soft clunk tanks have been used with success.  My RST 4 oz. actually holds more like 4 1/2 oz.

Of course, you can do like many, many people do and sink the tank into the LE of the wing.
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Big Bear <><

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