Comparative engine performance tables question

what you are asking for is an exhaustive list that would be accurate only for the day it was written, if it would be accurate at all, which it wouldn't be. there are so many variables that the numbers are essentially meaningless. now, with each engine you buy, included are a list of prop sizes that the mfr thinks are compatible with the engine. that's ususally a pretty good place to start. then you realize that all props are not created equal and comparing prop performance based on numbers is fairly meaningless. buy the engine, buy some props, and decide which one performs that "best" for your type of flying.

No, that's not what I am asking for at all, to quote my original post:

"I am trying to get a feeling for what props various classes of engines will turn at various rpms and I wondered if anyone knows a web site that has a collection of tables of such figures ? "

I'm certain that's total c*ck. Of course engines will perform differently under different conditions but I am looking for broad brush relative performance indications not absolute 10 digit accuracy performance figures.

I want to have a general idea as to the performance of a whole range of engines, I don't want to buy every engine in production and test them myself !

Your entire post was completely beside the point and totally useless.

Thanks anyway,

like i said earlier, moron, if there was such a site, it would be accurate only for the moment it was created, if it was accurate at all. sorry to rain on your black and white parade, but your question assumes a steady state of variables, which I am sorry to say, doesn't exist. but knock yourself out, and feel free to criticize the continous stream of modelers who agree with me, and who are supported by years of experience. maybe among them you will find another moron who actually thinks this stuff can be quantified.

Basic prop chart starter for 2 and 4 cycle

Prop Chart for 2 Stroke Motors

Motor Size (cu. in) Starting Propeller Alternate Propellers

.049 6-3 5.25-4, 5.5-4, 6-3.5, 6-4, 7-3

.09 7-4 7-3, 7-4.5, 7-5

.15 8-4 8-5, 8-6, 9-4

.19 .25 9-4 8-5, 8-6, 9-5

.29~.30 9-6 9-7, 9.5-6, 10-5

.35 ~ .36 10-6 9-7, 10-5, 11-4

.40 10-6 9-8, 11-5

.45 10-7 10-6, 11-5, 11-6, 12-4

.50 11-6 10-8. 11-7, 12-4, 12-5

.60 ~ .61 11-7 11-7.5, 11-7.75, 11-8, 12-6

.70 12-6 11-8, 12-8, 13-6, 14-4

.78 ~ .80 13-6 12-8, 14-4, 14-5

.90 ~ .91 14-6 13-8, 15-6, 16-5

1.08 16-6 15-8, 18-5 1.2 16-8 16-10, 18-5, 18-6 1.5 18-6 18-8, 20-6 1.8 18-8 18-10. 20-6, 20-8, 22-6 2.0 20-8 18-10, 20-6, 20-10, 22-6

Prop Chart for 4 Stroke Motors

Motor Size (cu. in) Starting Propeller Alternate Propellers

.20 ~ .21 9-6 9-5, 10-5

.40 11-6 10-6. 10-7, 11-4, 11-5, 11-7, 11-7.5, 12-4, 12-5

.45 ~ .48 11-6 10-6, 10-7, 10-8, 11-7, 11-7.5, 12-4, 12-5, 12-6

.60 ~ .65 12-6 11-7.5, 11-7.75, 11-8, 12-8, 13-5, 13-6, 14-5, 14-6

.80 13-6 12-8, 13-8, 14-4, 14-6

.90 14-6 13-8, 14-8, 15-6, 16-6

1.20 16-6 14-8, 15-6, 15-8, 16-8, 17-6, 18-5, 18-6 1.6 18-6 15-6, 15-8, 16-8, 18-6, 18-8, 20-6 2.40 18-10 18-12, 20-8, 20-10 2.70 20-8 18-10, 18-12, 20-10 3.00 20-10 18-12, 20-10, 22-8

"Boo" a écrit dans le message de news:4169299e$0$22755$ snipped-for-privacy@news.zen.co.uk...

maybe this will be of some help to you.

You are the moron as several sites did quite a bit of testing and all of them had results that correlated fairly well. They may not have had the exact same numbers, but when compared between brands and sizes, the pecking order was almost always the same. If you had been in this hobby for more than a few minutes, you would have seen this yourself.

Where is the RCFAQ when youneed it?

thanks paul, actually i thought you were one of the folks that would agree with me...the both of us having been in the hobby for some time, and knowing that the internet has spawned for a than a few sites of questionable integrity by well intentioned, but folks of limited experience. thus, i remain married to my original assertion that the numbers are meaningless, and i say that not because i nothing have else to do on sunday morning, but because i spent many years tinkering with props and engines and know that the numerical relationships that may exist between one prop and another of the same pitch and size has absolutely nothing to do with the performance one might get from either one, or that one mfrs can be directly compared with another...yes, I know that most of recent experience is with 100cc and larger engines, and I am one of a handful of people qualified to discuss the issues in producing an large scale aerobatic series, but there was a time when i diddled with the little stuff too.

PK

RC Report Magazine used to publish an extensive list of exactly what you're asking for. I don't know if they have anything online but you could check on their website and see. I've been out of RC for quite a while and I'm just now getting back into it but I remember they used a "weather/power factor" to try and make the numbers standard. While there will always be variations in the results someone else will get they at least provided a relative starting point for comparison. Cheers, jc

That's the site that came to mind when I read the original post. A very handy site it was.....color me a moron. mk

Paul, The reason I don't generally agree with you is that I participated in several comparison tests a while back abd the results were very repeatable and were also borne out with reports form a lot of other sources. Certain engines with certain props perform in a predictable manner. For instance, an OS FX .46 will turn an APC 10X6 at around 13-14K depending on the running conditions. It makes very little difference where or when the test was done. Also of note is that the TT Pro 46 matches the OS performance in virtually every test, no matter who does the test. A GMS .47 and Supertigre .45 will always turn 1-1.5K faster in every test. These are facts that have shown in several tests as well as observations by others.

Comparing brands of props (for instance APC to MA) is even easier. In every test I have participated in and read about, APC out performed MA props. Both in static thrust and in-flight performance. This is repeatable and verifiable.

If this is not what you are talking about, then I apologize.

It doesn't address your question directly, since it deals with electrics, but it helps develop a feel for how different props change the flight performance. I'm new to electrics, so don't have a good feel on its absolute accuracy. The relative differences among different props should still be meaningful. As a poor man's reality check, G2 is in pretty close agreement on performance. It was quite a bit harsher on predicted efficiency and amp draw, but static thrust, throttle response, and top speed performance felt very close. At to least to the extent that it "felt" like what the graphs and columns of numbers described. Maybe someone else can comment on the fidelity of both simulations. I tend to think, without any facts or experience to back it up, that MotoCalc might be a very optimistic on durations. It tells me I can expect half hour partial throttle flights driving a 1 pound foamie with a 340 mAh 3s1p pack and CD drive outrunner. G2 puts it back on the ground in well under 10 minutes.

Anyway, it was a few evenings of fun playing what-if. Watts are convertible to horsepower, so there might be some relevance for what you're doing. Maybe try the flat torque response of a brushless motor to simulate a mythical, well behaved two stroker.

Refer to "RCFAQ.COM" under FAQ at Alan's Hobby Web Links

regards Alan T

All motor info available or email me direct.

Refer to "RCFAQ.COM" under FAQ at Alan's Hobby Web Links

regards Alan T

All motor info available or email me direct.

Thanks to all who replied. Bobs' pointer to the archived version of the rcfaq was exactly what I was looking for.

Thanks again,