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Anybody's flying with Brodak 049? - Page 2 Empty

Anybody's flying with Brodak 049?

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Post  Scotland421 Sun Jul 04, 2021 8:11 pm

I use zero nitro home brew fuel in m' TD and medallion 049s I get 17,550 RPM on a Tornado 5X3, wi one head shim. I regretfully bought a Brodak 049. It gets 6K on the same fuel wi one head shim. The engine has 3. What a pathetic engine. I am gutted at the purchase.
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Post  fps60 Sat Jul 17, 2021 9:00 pm

Thanks to everybody. Just to wind up the above, I've decided to leave the Brodak as is. The only thing to do with reasonable efforts is to use fuel with higher nitro content. Overall approach can be summarized as follows: original (as-supplied) glow plug, 6x3 propeller, 15 % nitro fuel with 22-23 % lub oil (half-synthetic), and a lightweight airframe (something like Baby Flite Streak or similar) to fly in calm weather on 35-feet lines. By the way, that's absolutely in line with manufacturer's instructions.
And as soon as I want to 'feel the power' of a half-a engine I'll switch to MP Jet 061, either diesel or glow.
Recently I'd acquired the MP Jet 061 BB Special in addition to my diesel version of this engine. That's a promising performer.

Anybody's flying with Brodak 049? - Page 2 Mp_jet10

I have not tired it yet but, according to feedback, it should be a real powerhouse in its Class. My experience with its diesel counterpart also speaks in favor of this assumption. Here it is:

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Post  Scotland421 Sat Jul 17, 2021 9:05 pm

The MP Jet has brute BHP.
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Post  fps60 Sat Jul 17, 2021 9:10 pm

I guess so. As a matter of fact, it has been designed with a view of performance use. They (MP Jet) always highlight that their engines are not intended for use by beginners.
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Post  Scotland421 Sat Jul 17, 2021 9:13 pm

Anybody's flying with Brodak 049? - Page 2 S-l16010

My better power alternative, more grunt than ae TD
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Post  Scotland421 Sat Jul 17, 2021 9:14 pm

@fps60 wrote:I guess so. As a matter of fact, it has been designed with a view of performance use. They (MP Jet) always highlight that their engines are not intended for use by beginners.
The glow button is difficult tae get.
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Post  fps60 Sun Jul 18, 2021 9:59 am

No problem, you can buy them directly from MP Jet. They have all engine parts in stock and offer many other useful things including those for people who rely on electricity.
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Post  fps60 Tue Jul 20, 2021 9:12 pm

By the way, if anybody here has ever run MP Jet 061 BB Special I'd appreciate if you advice me with regard to the pressure fitting that is in the back cover. The engine comes complete with two fittings, one is .25mm and the other is 1mm. At that, .25mm fitting is factory-installed. However, Dick Roberts in his review of this engine told that he had failed to start it with .25mm fitting and was successful after he had replaced it with 1mm one:

http://sceptreflight.com/Model%20Engine%20Tests/MP%20Jet%20061%20BB%20Special.html

On the other hand, AFAIK, all MP engines are tested at the factory before release. I can not believe that they could release an engine that failed to start or that they replaced the fitting after test. Furthermore, they do not recommend using larger fitting to avoid power loss. May be Dick's tank was too large or something else was wrong with fuel system?
I feel confused about that.
So I ask anybody who has actually run this engine in pressure fuel feed setup to let me know exactly the pressure fitting size. Thank in advance.
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Post  Ken Cook Wed Jul 21, 2021 12:37 am

I run all kinds of different engines on pressure. The problem is the same with all of them. If the hole is too large in the fitting, the engine doesn't run correctly. I've never seen a manufacturer provide the correct size nipple. I always downsize the opening if the nipple is steel. I use a very fine wire almost thread like and I blacken it over a candle flame. I insert it into the pressure nipple and solder it, when cool I remove the wire. The carbon on the wire prevents the solder from sticking to it.

If the hole is large, it causes the engine to surge back and forth or floods instantly when cranked over. I generally start all pressure setups with the same technique I use when running bladder pressure. I use a pinch off device to prevent the engine from flooding. I get the engine to fire up on prime and release the pinchers.

My gut feeling tells me that the venturi is too large as well which is why the engine is provided with a pressure nipple. I don't own the glow version, I own the diesel which is completely different. By the pictures I've seen they suggest to me that the venturi is large. One possibility that might assist in starting and any funny business is to place a one way valve in the pressure line. I've done this with some engines while others didn't require any .
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Post  fps60 Wed Jul 21, 2021 11:38 am

Thank you Ken,

Your approach is basically the same as described in the engine manual. And the hole-reducing method is very interesting, I'll remember it. BTW, it was mentioned in the review that the fitting with large diameter caused fuel flowing out from the venturi opening at relatively low rpm. So I'm going to proceed with 0.25mm fitting, at least to start with. Still, there are two questions I can not answer:

First, why had Dick Roberts failed to start the engine with .25mm pressure fitting? and
Second, what was the reason to include additional 1mm fitting in the engine delivery pack?

In fact, MP Jet 061 Diesel venturi is the same as that of 'mainstream' glow version. Their parts are mostly interchangeable (except engine top, of course). What I mean here is the Racing Special glow version which features include englarged venturi section (16mm2), remote NVA assembly, special crankshaft fit (according to the manufacturer), and back cover with pressure fitting. Of course, I can simply replace the venturi and the back cover with standard parts and run it as a normal glow MP Jet still enjoying advantages of highly accurate crankshaft fit and remote NVA that is really essential for these engines with NVA damn close to the propeller plane, and may be I'll do so in future but I'd like to see first how far can it go. Some people say that they've managed to rev it up to 30k with 5x2 prop.
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Post  Ken Cook Wed Jul 21, 2021 12:17 pm

I don't know what event was specific to the use of the MP Jet .061. There's a chance that the tanks used for the engine had a restriction device soldered into the pressure tube going into the tank or there was one in place in the tubing itself. This would've allowed the larger nipple. I just don't know the answer. What I've discovered in running crank pressure is that some engine typically larger demand that larger size nipple. Small engines though from my experience don't require a large nipple and can become a real pain in the rear if it's too large.
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Post  fps60 Wed Jul 21, 2021 1:17 pm

I'm not sure also about intended use of this engine in terms of competition or contest. May be, there are some racing events, or it could be put in a F1P (J) freeflight bird. I could also assume it as a half-a combat engine but never heard about such use. Anyhow, it looks like a precision engine with very good workmanship. That's especially true for the Racing Special version having perfect fits. When you turn it by fingers you have just the right and expressed feeling of passing through the TDP without leak and without bite while there is no even slightest play anywhere. That is why it does not require a long-time run-in (only 15 to 30 minutes recommended by the manufacturer) despite its iron-steel construction.

As for restriction devices, Dick Roberts did not mention anything like that in his review. But he also had not provided any reference to his fuel system (tank size, tube diameter and length, etc.) So I have to proceed based on trial-and-error approach relying mostly on instructions and data provided by the engine manufacturer.
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Post  ffkiwi Wed Jul 21, 2021 2:54 pm

@fps60 wrote:I'm not sure also about intended use of this engine in terms of competition or contest. May be, there are some racing events, or it could be put in a F1P (J) freeflight bird. I could also assume it as a half-a combat engine but never heard about such use. Anyhow, it looks like a precision engine with very good workmanship. That's especially true for the Racing Special version having perfect fits. When you turn it by fingers you have just the right and expressed feeling of passing through the TDP without leak and without bite while there is no even slightest play anywhere. That is why it does not require a long-time run-in (only 15 to 30 minutes recommended by the manufacturer) despite its iron-steel construction.

As for restriction devices, Dick Roberts did not mention anything like that in his review. But he also had not provided any reference to his fuel system (tank size, tube diameter and length, etc.) So I have to proceed based on trial-and-error approach relying mostly on instructions and data provided by the engine manufacturer.

It was originally intended for use in F1J....and actually sold as their 'F1J special' by some vendors...but the bottom has largely dropped out of F1J as a class, leaving F1P as a sort of successor class-though with more restrictive rules than F1J. never heard of it being used for combat-I suspect it would be considered a bit bulky and slightly heavy in comparison with the 1/2A combat engines of the 90s and also the current ones. MP Jet were a bit conservative-the basic engine could be-and was-by one noted engine reworker-tuned to much higher power levels than produced by the factory F1J Special-which is more along the lines of a well setup standard MP Jet with a big intake and extra attention to fits....whereas the Galbreath one was extensively modified in several key areas to the extent that it would equal the AD 06...which was the F1J yardstick against which all other contenders were measured at the time (early mid 1990s...)

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Post  fps60 Wed Jul 21, 2021 6:44 pm

Thank you Chris,

Very meaningful data. But it does not explain the label 'Racing Series' on the box. It scarcely could be associated with F1P or J Class. Perhaps, there were (or, may be, still are) some other applications, at least estimated.

The main advantage of these engines in terms of maintainability is that they are still being in production currently and the manufacturer maintains comprehensive stock of spares and accessories.

By the way, the button 'Thanks' on other posts is inactive and inaccessible for me. Could anybody give me a hint why?
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