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Post  bsadonkill Mon Jun 10, 2024 5:23 pm

I am having an ignition problem with an .23 OHLSSON engine. What kind of primary resistance should I expect with a 3 Volt coil? I have a Smiths coil that I am having versus resistance readings. I have readings as low as one OHM. I think I am draining my 4 AA batteries to fast. What amount of primary resistance should I expect with a Three Volt Coil?Ignition Problem 415
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Ignition Problem Empty Larry Davidson --- can help you out on all ignition problems?

Post  sosam117 Tue Jun 11, 2024 5:28 am

Larry Davidson --- can help you out on all ignition problems.

I have known Larry for years as a member of SAM (Society of Antique Modelers).

Here is his web page:
click on the link below
Larry Davidson Ignition Systems


Here is his web page to ask him about your Ignition problem:
click on the link below
Contact Larry Davidson -- problems/answers
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Post  bsadonkill Tue Jun 11, 2024 5:51 am

Thanks, sosam117 I could use some expert advice!
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Post  getback Tue Jun 11, 2024 6:01 am

When you find out would you post that info Please Very Happy
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Post  bsadonkill Tue Jun 11, 2024 7:15 pm

Ok I have got pretty good spark now. The problem is it took 8 AA batteries to get there. I do get some spark with just 4, but it's weak. I wonder if I could use 3.6-volt lithium-ion batteries in place of 1.5-volt batteries in parallel series to get to get 3 volts?Ignition Problem 416
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Post  getback Wed Jun 12, 2024 6:03 am

Only one way I know of try it and if it don't burn the points or plug out then Ok Or get a reducer for the 3.6 to adjust down to 3.0V .. I don't know . Shocked
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Post  bsadonkill Tue Jun 18, 2024 12:51 pm

Well, it does run. Using 85 octane non-alcohol gas and S.A.E. 70 weight Drag Specialties oil. Do you think a 10x5 prop might be a little big for it? I have no recommendations for prop sizes.Ignition Problem 128
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Post  GallopingGhostler Tue Jun 18, 2024 7:19 pm

The only engine article I know of is: https://sceptreflight.com/Model%20Engine%20Tests/O&R%2023.html.

Unfortunately, there is no reference to where this article was obtained from. It states using a 9x6 prop of the day turning at 8,900 RPM.

IMO, props in those days tended to be wider bladed, so, I can't see why a modern narrower blade 10x5 prop would not work or at least be a good starting point. Now mind you, I have no experience with ignition engines, only glow.

Someone here was selling one with a 1939 O&R 9x5 prop:
https://www.rcgroups.com/forums/showthread.php?4319277-O-R-23-vintage-ignition-engine-new-prop#post50739619

Good luck, and look forward to your experiences with this rarity of an engine.
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Post  getback Wed Jun 19, 2024 6:03 am

Thumbs Up that's good news I see you went with the 3V setup , I would try and source you some wood props , I found mine at swap meets 12 and 14 " I think the pitch is 6 would have to go look ? Did you get a chance to tach it ? That would help to make sure to not over speed it .
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Post  bsadonkill Wed Jun 19, 2024 9:18 am

I don't have a tachometer, so I have no way to check it. And as far as overrevving goes I don't know what the maximum RPM would be.
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Post  GallopingGhostler Wed Jun 19, 2024 9:43 am

bsadonkill wrote:I don't have a tachometer, so I have no way to check it. And as far as overrevving goes I don't know what the maximum RPM would be.
Some have been using an app on cellphone, which bases the RPM on the sound of the engine.

With your 10x6 prop, I don't think you are in any danger of over revving the engine. Remember that the Sceptre Flight article tester was using a 9x6 prop of the day.

From what I recall, Walt Musciano and others spec'd this engine on planes that today we might use a modern .09 Schneurle or legacy .09 to .15 glow of the 1960's. 9K RPM is not too far off from a say, my Testor McCoy .35 with 10x6 prop would be turning on my Ringmaster C/L plane running a rich 4 cycle.

These O&R's I heard were good engines, not power houses, but reliable and they dominated until other engines entered the scene.

https://www.adriansmodelaeroengines.com/catalog/ shows an ignition engine running on his opening web page. Here's Adrian's review of the O&R .23 ignition engine:

https://www.adriansmodelaeroengines.com/catalog/main.php?cat_id=409 . Here he says,
Adrian wrote:At a rich 4-cycle setting the Ohlsson is quite at ease, accepting a wide range of needle settings before approaching 2-cycle mode. Then it becomes more exacting. The front rotary versions were particularly keen to jump into 2-cycle mode with one more click leaner when lightly loaded, and then stay there. However, optimum mixture when at full temperature was a click or two richer. Again, evidently necessary to resist overheating.

Data tables circa 1940 list recommended propellers of 10-12 inch diameter and 6-7 inch pitch, revised later to 10x6. Then 8x9 or 10x5 for the 1949 FRV version, which should turn at 7,000+ RPM. Peak BHP was said to be developed at 9,400 RPM. Spot tests with a genuine O&R 10x4 wood propeller were a few hundred RPM less than our modern APC 10x5.

Turning larger propellers was fine - the seemingly chunky bottom end took the slog in its stride. However, all variants were happier on lighter loads. The O&R 23 seemed poised for higher speeds than the recommendations suggested. This is not surprising, considering the 1.1 to 1 bore/stroke ratio along with the generous cylinder port sizes and durations (exhaust 143 degrees, SP intake 122 degrees).

Adrian used a modern APC 10x5, so your choice of initial prop, a 10x6 is in the ballpark. However, his numbers below suggest maybe something just a touch milder. Further down, he lists the props he used and the RPM's he obtained on various fuels.

Adrian's Props versus RPM:

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Adrian's Brake HP and Torque Curves:

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According to Adrian's tests, the spark engine on gas peaked out at 11,400 RPM at 0.27 Brake HP.

Optimal static run would be about 1,000 RPM less on a test stand, since it would unload to near maximum HP in the air. A prop meeting such would provide the best thrust.

So for myself, I'd be seriously looking at a prop say around a 10x3, 9x5, etc. (Not all props are equal, so some experimentation will be involved. Most do this once they have it mounted on a plane.)
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Post  bsadonkill Wed Jun 19, 2024 7:55 pm

Thanks for the information. People on this web site are very helpful very friendly. Looks like a 10-inch prop would be fine to start with. I have a plan for the Cleveland Viking. I think it would be a good winter project.
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Post  GallopingGhostler Thu Jun 20, 2024 7:48 am

bsadonkill wrote:Thanks for the information. People on this web site are very helpful very friendly. Looks like a 10-inch prop would be fine to start with. I have a plan for the Cleveland Viking. I think it would be a good winter project.  
You're welcome.

Looking forward to your experiences with your O&R ignition and the Cleveland Viking or other design build using this engine, plus your further engines tests and use, mixture of fuel you finally decided on and etc.

Just so I'd know what model you are referring to, found: https://outerzone.co.uk/plan_details.asp?ID=6139 Viking 110% by Doc Mathews from Flying Models June 1979, 48in span
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Outerzone plan thumbnail.

DB Matthews upscaled it a touch so it's wing area would match the Playboy Junior. The Viking is a very attractive cabin model. Reminds me of Walt Musciano's slightly larger Sporty.

https://outerzone.co.uk/plan_details.asp?ID=7049 Sporty II by Walt Musciano from Model Airplane News November 1950, 65in span
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Outerzone plan thumbnail.
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Post  Ken Cook Thu Jun 20, 2024 1:15 pm

The .23 is a small engine. I personally feel like the 10" is too much. Gasoline runs much hotter than glow. This will certainly make settings a bit difficult when it heats up. As Adrian's article states, these are much happier on smaller props. I prefer Rev Ups because they're generally a tad light on pitch then what's on the prop itself. What concerns me is shaft. In the event of a backfire, a prop such as a APC 10x5 is quite weighty and that can do some damage. I agree about the bottom end but the shaft is pretty small. The shaft is well supported and the sideport shaft is solid which is beneficial over the FRV version but the metallurgy on these engines are by no means superior.
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