Author Topic: Brodak 25 set up? (Read 4740 times)

Jim Oliver · « **on:** May 02, 2006, 10:58:01 PM »

Hey guys,

My LHS has a couple of the new Brodak .25's on order--I'm thinking about one for my as yet unfinished Flight Streak ARF.

Any suggestions? How about it Bob Z?

Thanks,

Jim Oliver

Bob Reeves · « **Reply #1 on:** May 03, 2006, 03:20:50 AM »

Break it in per the instructions that come with it.. Several short runs with a cooling off period using a 9-4 prop.. Any 10% nitro 20-22% oil fuel seems to work. Thunderbolt glow plug, 3 ounce Hays tank. muffler pressure, just like the Bret Buck 20 FP setup.

Tried a GRW 3 1/4 ounce chicken hopper but didn't like the drastic difference between ground and air rpm.. Slobbery rich on the ground was still too lean in the air. Hays tank fixed the problem.

I am using one of the first run Brodak 40 mufflers with the small outlet. The muffler that comes with it has a much larger outlet and thought it would be better off on one of my Brodak 40's while the small outlet would be great with the .25.. It worked..

My Brodak .25 runs just as consistent as the 20 FP I have on an identical airplane. Haven't played with enough props to make any kind of recommendation. Started with an APC 9-5 but lap times on 58 foot were too slow at 5 1/2 seconds. This is running it in a rich two stroke, set on the ground so it just breaks into a two stroke with a small burble once in a while.

The only other prop I had I thought might work was a yellow plastic 9-6, think it is a Grish but not positive. It worked great, (5 second laps with a rich two stroke setting) but can't tell anyone how/where to get one. Thinking it is kinda flexible so not believing it maintains a 6 pitch in flight, a wide blade 9-5 or 9-51/2 might work just as well. I just got lucky with the muffler and prop but it works so I am not planning on changing anything....

peabody · « **Reply #2 on:** May 03, 2006, 05:58:38 AM »

I know that the development was done with a couple aeroplanes using .012 X 52-56' lines....and either a 9 X 5 or 4 prop....10% Powermaster 22% oil fuel

Bob Reeves · « **Reply #3 on:** May 03, 2006, 07:21:33 AM »

On 52's it would probably be in the 5 second area with an APC 9-5 but it does fine on 58's with the Grish(?) prop. I'm using the same set of lines for both airplanes 12-58's and getting close to identical performance.. As yet I see no reason to go shorter.. The airplanes are close to Flight Streak numbers, tail moment is a bit longer, airfoil is slightly different and 420 square inches. Can't remember what the wing area of the Streak is but it's probably close.

I feel the Brordak .25 is a real winner and as I can afford it start replacing the FP-25's on my other knock around profiles. The FP-25 is a good engine but once you have experienced the consistent run's produced by an FP-20 or Brodak .25 one gets spoiled.

Jim Oliver · « **Reply #4 on:** May 03, 2006, 11:42:53 AM »

Thanks,

I was a little concerned that the FS would be overpowered--although when I was a kid we wanted all the power (speed) we could get.

Planning on 58-60 ft. lines, we will see how that works.

Thanks again,

Jim Oliver

Leester · « **Reply #5 on:** May 03, 2006, 01:52:18 PM »

I don't know the ins and outs of engine mfg. designing etc. so why do you pay the same price for a B-25 as you do for a B-40?

Bob Reeves · « **Reply #6 on:** May 03, 2006, 02:28:57 PM »

The big costs are in development and manufacturing prep. The only real difference between the two engines (as far as cost) is an ounce or two of aluminum. John does not have the advantage of being able to recover these costs by selling the same engine to RC'ers. OS LA's are identical engines for both RC and control line, OS has a much larger market, spreading the development costs over more engines.

If you compare the cost of dedicated stunt engines in the same league like Stalker and Double Star the Brodak engines are a pretty darn good deal.

Leester · « **Reply #7 on:** May 03, 2006, 03:30:01 PM »

Thanks Bob: That makes sense even to me.

Alan Hahn · « **Reply #8 on:** May 04, 2006, 07:50:16 PM »

For grins I plotted the cost of the LA series engines vs displacement. I think you can see that the cost doesn't go to zero as displacement. I am guessing the only reason the cost does decrease is because people think that smaller should somehow cost less, although the effort is exactly the same--I would even guess it might be a little harder to make a smaller engine. The materials aren't a big deal I bet. The cost of the LA65 makes little sense though, I think they must not sell too many of these.

phil c · « **Reply #9 on:** May 05, 2006, 03:20:37 PM »

Another way to look at it,
The cost of materials is basically the weight of the engines(talking about a series like the LA, which all use the same basic design). Twice as much materials will cost twice as much.

The machining, which is all machining 2D surfaces, would go by the length and height of the engine. You make the engine twice as long and tall and it will have approx. 4x the machined surfaces in it.

The 65 is maybe a bit expensive, as you suggest probably due to low volume. The other anomaly is the 46. Based on displacement it should be a bit more. But since it is exactly the same as the 40, except for the piston diameter, it really shouldn't cost much if any more, and it doesn't.

Hard to argue that the LA series are "cheap" or low quality motors when they run so well and seem to last pretty darn well too.

Bob Reeves · « **Reply #10 on:** May 07, 2006, 04:52:49 PM »

Put 4 more flights on the Brodak .25 powered SHIM today, boy.. the more I fly that engine the more I like it. All 4 flights were one flip starts, fuel and flip, rock solid from first lap till just before it ran out of fuel. Just under 7 minutes on 3 ounces of 10% . Yep John has a winner...

Jim Oliver · « **Reply #11 on:** May 07, 2006, 08:23:27 PM »

Sounding better all the time!

Thanks,
Jim Oliver

Jim Oliver · « **Reply #12 on:** May 09, 2006, 09:31:16 PM »

I picked up the Brodak 25 today--it looks great.
Plan to run it on the test stand tomorrow, and maybe fly it Friday.

Further info when available.

Jim Oliver

Louis Rankin · « **Reply #13 on:** May 09, 2006, 10:15:16 PM »

Be on the lookout for my review of the Brodak 25 in the first issue of "Control Line World". The Brodak 25 in one phenominal engine!!

Zuriel Armstrong · « **Reply #14 on:** May 10, 2006, 06:21:40 AM »

I've seen folks seen an FP25 on a Nobler size plane with good success. Will the Brodak 25 power a 550 sq/in plane under 40 ozs ? I would be interested if it could. I have flown LA25 powered Prowlers and RD-1's and thought it was a nice package.

Jim Oliver · « **Reply #15 on:** May 10, 2006, 08:53:33 AM »

Hey Louis,

How do I get the Control Line World magazine?

Jim Oliver

Bob Reeves · « **Reply #16 on:** May 10, 2006, 11:50:23 AM »

Hi Zuriel,

Brodak .25 and FP .25 are completely different animals, power wise it compairs to the FP .20, great for a Flight Streak, Ringmaster or anything in the 400 to 450 sq in range.

My personal experience with the FP .25 is it's too much for a Flight Streak and not quite enough for a Nobler. Have heard before the FP is OK on a light Nobler but I can't build that light

Zuriel Armstrong · « **Reply #17 on:** May 11, 2006, 06:20:23 AM »

Thanks Bob. Will I see you at Dallas this year? I plan on making it out to see you guy's this year too.

Jim Oliver · « **Reply #18 on:** July 16, 2006, 02:46:41 PM »

Hi guys,

I broke the Brodak 25 in exactly per instructions.

It is mounted on a Flite Streak ARF, 3 oz. uniflow, no muff pressure, 10% nitro/22% oil(50/50 castor/syn.) APC 9x5--launch at 10,500. This rpm is what I would call a very wet two cycle. Don't remember which glow plug--probably K&B 1L. If some one wants to know, I will pull it out and look.

The 3 oz. tank produces about 8 minutes with this set-up--a 2.25 or 2.5 oz. would be better, I think. The engine run is very steady, basically no change until last couple of laps which are a faster 2 cycle but not screaming. BTW, the tank is mounted on the engine center line, on the outboard side of the nose--just glued to the nose with clear RTV.

Choke 4 turns, pull thru 4 times, connect glow power, turn once to get the bump then 90 % of the time--one flip starts.

All in all, this is probably the most friendly CL engine I have ever used--I am looking for an excuse to buy one of the .40s.

Cheers,

Jim

peabody · « **Reply #19 on:** July 16, 2006, 04:19:35 PM »

Jim...
Order up a Cardinal or Pathfinder ARF...

Jim Oliver · « **Reply #20 on:** July 16, 2006, 07:21:30 PM »

I have a twice rebuilt Cardinal ARF with ST 51 (Italian) and a Pathfinder ARF under construction!! Hope the Pathfinder flies as well as the Cardinal.

Cardinal "twice rebuilt" 'cause I flew it into a "celestial object".

I have been able to do all the beginner pattern except square insides--too high, not pretty, but recognizable since Dec. 05/Jan 06.
And so far I have only totally destroyed one model!

Great fun!

Jim

Steve Scott · « **Reply #21 on:** July 17, 2006, 01:05:54 PM »

Quote from: Pattern Student on July 16, 2006, 07:21:30 PM

I have been able to do all the beginner pattern except square insides--too high, not pretty, but recognizable since Dec. 05/Jan 06.
And so far I have only totally destroyed one model!

Great fun!

Jim

Aw Jim... If you're not destroying an airplane a month, you're not trying hard enough!!!

My wreckage rate is getting better. It was always the outside squares which do me in but that was before the advent of the beginner pattern without the outsides. I've got about a 90% success rate on the outside loops - at least I manage only to "graze" the ground instead of attacking it.

Jim Oliver · « **Reply #22 on:** July 17, 2006, 04:24:56 PM »

Steve,

Thanks for the "encouragement"!

Jim

dennis lipsett · « **Reply #23 on:** July 22, 2006, 02:11:30 PM »

Quote from: Bob Reeves on May 03, 2006, 02:28:57 PM

The big costs are in development and manufacturing prep. The only real difference between the two engines (as far as cost) is an ounce or two of aluminum. John does not have the advantage of being able to recover these costs by selling the same engine to RC'ers. OS LA's are identical engines for both RC and control line, OS has a much larger market, spreading the development costs over more engines.

If you compare the cost of dedicated stunt engines in the same league like Stalker and Double Star the Brodak engines are a pretty darn good deal.

I'm probably get told about this but the Brodak 40 seems to be the same as the Double Star 40. That being the case the developement costs were already figured into the design.
Dennis

Bob Reeves · « **Reply #24 on:** July 23, 2006, 03:42:28 AM »

Quote from: dennis lipsett on July 22, 2006, 02:11:30 PM

I'm probably get told about this but the Brodak 40 seems to be the same as the Double Star 40. That being the case the developement costs were already figured into the design.
Dennis

The only thing common between the Double Star and Brodak is they are both 40's.

Steve Helmick · « **Reply #25 on:** July 23, 2006, 04:30:11 PM »

The DS .40 is a baffled piston design evolved from the Fox .35 at Tom Dixon's request. The B.40 is a schnuerle ported design evolved from the Fp .40 at John Brodaks request, but both are done by the same manufacturer, DS. They look a little similar, but that's to be expected.

Steve

john e. holliday · « **Reply #26 on:** July 23, 2006, 10:13:24 PM »

I have to agree that Brodak 25 is one strong engine. Put four runs on the ground. The next five are in the air. Have Emmy for break in pilot. The plane is a Brodak Mauler that came out super light. With the Fox 35 Stunt I was doing full patterns on second flight. I messed up somewhere as it is one terrific flying airplane. Now with the B-25 I was doing lazy eights and loops on the eighth and ninth runs. Still a little wet on the needle setting, but, it seems not to speed up much when climbing. The fuel tank is a plastic four ounce with my uni-flow setup. With two ounces of fuel getting well over four minutes. Prop I am using for break-in is Top Flight Power Point 9-5. Fuel is Powermaster 10% nitro, 22% oil(1/2 &1/2). Later, DOC Holliday

Author Topic: Brodak 25 set up? (Read 4740 times)

Alan Hahn