Brodak 40

Please advise suggestions to make my Brodak 40 run consistently. It is hard to set the needle valve to a consistent run.

Peter,

Are you using a good fuel with the correct oil content? How much time do you have on the engine?

Is it fully broken in? Check fuel, plug, prop, tank. A whole lot of varibles. Just do one at a time.
Bill <><

You are getting good advice here, but give us specifics. How much time do you have on the engine? You should put some break in time on a test stand, and not at a blubbery rich setting. Get it up to operating speed (and temperature) and then set it just slightly rich.

OK, you did that, now what prop and fuel are you using and how are you trying to run the engine?

One thing I would suggest is make sure your bolts--especially the back plate bolts are all tight, and also check to make sure the needle valve body is positioned correctly. These use the double hole body and they should be positioned side to side, not up and down.

One more thing to check is for fuel foaming. Is the tank solidly mounted? Does the tube come from the tank directly to the engine? If there is a filter in the line, make sure the filter is not leaking. Make sure there is no "junk" in the needle. Take the needle out and squirt some fuel through the body backwards.

You probably have a problem like this somewhere in the system, as the engine shnould run fine.

Is the cylinder in correct position? Are the exhaust slots lined up with the case? Brodak had some problem with that.

Did you break it in exactly as the instructions say. Before I bought one i asked several people who owned them and the ones who were getting nice runs all made the point that they had broken it in as directed: 20 or more short (about 2 min.) lightly loaded runs right on the 2-4 edge with full cool down between. A couple of fliers who weren't happy commented they hadn't broken it it as directed.

I spent last sunday timing at a local Free Flight contest with my New Brodak 40 on a test stand with a 1-1/3 oz tank, a Zinger 9-6, no muffler, 5% x 25% fuel, 60 degree temps. I set a kitchen timer for 12 minutes after each run so the engine could fully cool down. At 12 runs it varied about 1,000 rpm. At 18 runs, about 500. At 25 runs I couldn't measure the variation through all but the last 10 seconds of the run. RPM on this set up was 13,100.

This would have been a lousy engine to fly until near the end of the process. Now it's an instant starter and rock steady on the stand, even with a lousy tank set up. It hasn't been flow yet.

My point is that early in the process it was very unsteady and would not hold a needle setting. By the end the whole personality had changed. Eliminate the fuel system problems and if it still doesn't work, I'd say go back and restart the break in process exactly as directed.

Good luck! I'd like to hear how it works out.

I agree with Jeff. I broke in my (now Gary Tultz's) Brodak .40 exactly as Jeff did and observed the same progressive improvements each run.

I used Powermaster 10% nitro 22% oil (50% synthetic, 50% castor).

Gary mounted it in his resurrected Hurricane and he loves it. It was good enough after the twenty runs to fly a solid pattern.

I'm convinced that the short runs with full cool down is the best break-in method for all engine types. It's is faster and more economical than my old 4 oz. full tank runs and putting 1 1/2 gallons thru an engine and still only being marginally close to pattern ready.

Anybody have any advice on a good prop/RPM combination for the Brodak 40?

On my Nobler Arf, I use a BYO 11-5 prop, and it runs the full pattern in a strong 4 stroke. I have also used thinned down 11-5 and 12-5 (cut to 11.5") Zingers. If anything it still moves too fast for me (4.9 s laps on 60 foot eyelet-to-eyelet lines). I am thinking about longer lines, I would like to be at 5.2 s laps, just to give me a bit longer to worry during the first downward leg of the outside square.

Just had a chance to fly my Brodak 40 on my NoblerArf at lunch today. Turns out I fixed a problem.

Last year the combo was running pretty solid (at least when I didn't try to dig trenches with it). However this year so far, the running has been pretty inconsistent--going back and forth from 4 to 2 stroke during a run. I tried the usual stuff, plug, fuel, filter,.. but it still wasn't running well. So at Fred K. and Kurt K. 's suggestion I decided to pull the cowl last night and check over the fuel tank and tubing.

It turns out that the problem was that the front tank support had broken away from the fuse side, allowing the front of the tank to bobble up and down. So fixed it, and today was rewarded with a nice 4 stroke run with lap speeds @~5.1 s. Felt really nice.

It goes to show you that causality is still applicable to stunt runs.

>Anybody have any advice on a good prop/RPM combination for
>the Brodak 40?

Will,

My friend, please call Keith Varley at your earliest convenience. He's got **lots** of advice for you, although most of it seems to concern flying in calm conditions, his new Saturn, who is allowed to fly it, who is banned from his immediate pit area.

Hoping to see you this weekend. Tell Duck to pack his tool box. The one in which he keeps his brain.

And will somebody *please* be certain Bruce's nicad plug lighters are in absolutely perfect condition? Including a full charge?

Oh, your question. What about an APC 10-6? Or if the motor is real healthy, APC makes a 10.5-6. For revs I would want to see about 28K, well into ear-bleed territory. Get somebody other than me to launch for you. Keith, maybe?

Dan

>Anybody have any advice on a good prop/RPM combination for the Brodak 40?

The APC 10-5 has worked well in several applications-less speed, more grunt than the 10-6. The somewhat rare, but available APC 10.5 X 4.5 has been an even better performer on a couple of airplanes(ARF Nobler, Oriental).

Guys, Best way to run a B-40. Read Dick Fowler's post. Remember, this is a Schnurle eng. (I'm never sure how to spell Schn. whatever). It has an A.A.C. cyl. assy. with good pinch. (this means horsepower). The instruction sheet recomends an 11-4 prop. This Eng. properly broken in has the guts to turn a Werwage/Phelps 10.5-4 carbon two blade or a Tornado 10-4 three blade at a ground launch of 10000-10200 rpm. (These are what I use). It unloads in the air into a high rpm pipe style 4 stroke.(poor mans Aero tiger 36) My Veco Hurricane has never flown better. Guys, let your modern motors rev, use 4pitch props, thats what they want to run.---

Just to bring this back to the top. I use a Thunderbolt 4stroke gloplug, homebrew fuel (10%nitro, 22%oil, half UCON LB 1145 and Sig AA castor) and a Sullivan RST 4 oz clunk tank with Uniflow soldered to the pickup ala Bob Hunt. Runs the same upright or inverted. I ground the pickup down at a 45 deg. angle for a good shut off at the end of the pattern.

try talking to tom hampshire by email if you can, he knows a lot also

It appears that are nice little Brodak 40 is capable of running in many different ways.I have been running mine on my Oriental with a 10-6 Old wide blade top Flight wood,Like a BYO.I am running 10% Coopers control line blend 23% oil 50-50.I am on 60ft eye to eye lines. My plane weighs 38oz with stock muffler on the motor.It does 5.1 sec laps in a 4 stroke and has a beautiful break on the ups.I get approx 8 min 15 secs on my 4oz metal uniflow tank.I am very happy with he setup.Dennis