LIMITED-B Prop Tests please ?

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Lou Melancon
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Post by Lou Melancon »

Ron,
I didn't give up B because it was too fast, nor did I give up Scale. I gave up B so I could have the time to build for two events instead of spending all my time keeping up with only one. A funny thing happened, all of a sudden there were many more contests I could go to that featured SSC. Turned out to be a good thing for me.

If you are dissatisfied with the rules cycles, rules change processes, and the time cycles please petition your District Rep. That is the a process for you to elevate your concerns. Nothing official happens on the Soapbox or the Forums.

Lou Melancon
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Post by Web-Pilot »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by RHorton</i>
For now to sanction a RCCA 2610 event it must be a class c event, <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Ron, This is not correct. I have two Class A 2610 meets this year and one Class AA 2610 meet. All you have to do is include on the sanction application section 4 where you list the deviations from AMA rules, a short statement such as:

"Event 750 Section 3.3.1 2610 Scale maximum dry weight for single engine design on 3.5lbs will be in effect."

And you will get a Class A or AA sanction. Easy enough.

George



George Kerr
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merciless
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Post by merciless »

Prop Test:

Norvel .25 Bushing: Very good condition
Stock muffler; standard tank with muffler presser only.
Airframe 3lb 500sq in wing
This is what I fly in open-b
Fuel Sig ½ and ½ 15% nitro 20% oil plus 2.5 oz of caster (22% oil)
Wind at 17 MPH

MAS9x4 18200 RPMs
Flew great not quite what it is with the Mac and pump but close. With stock muffler missing 1000 RPMs. Rating of 9.5 for performance.
Rating of 9 for Speed

MAS10x4 14600RPMs
Flew great slower then the MAS9x4 but not that much (I was expecting it to be slower). Could turn on a dime and lots of climb. Lot of thrust so cross wind launch was a snap.
Rating of 9 for performance.
Rating of 8.5 for Speed

APC10x3 14800RPMs
Few great slower then both the MAS. This is about what I was expecting with the MAS10x4 a noticeable difference in speed. No problems with cross wind launches or turning. I did notice it made my engine run a bit hotter then normal.
Rating of 9 for performance.
Rating of 8 for Speed (More what I would expect for Limited B)

Conclusion?
I would be willing to go with either, just as long as everyone used the same prop. (Pick one) MAS will be more durable but not as slow as the APC. (But it’s not that big of difference)


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"Merciless" Mitch Eaves
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Post by Jimbo »

double post

Limited-B
Try it,you'll like it !
Jimbo
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Post by Jimbo »

Thanks Mitch, good job!
What wing are you using? 500 sq in seems a little small.[?]
You say it got hot? Did you run it a little on the rich side?

Limited-B
Try it,you'll like it !
merciless
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Post by merciless »

The airfoil is a S3086 with 9.75Root and 6.5Tip (with ailerons). It flies well, how ever I plan to have a new bigger wing for next year. Yes the engine did get a bit warmer then normal, but not to excess. I can normally touch the head after a flight. With the APC I could but only for a very short time. Yes I had the engine tuned correctly. Just something I noted not a big deal. The APC 10x3 seems to keep a constant load on the engine.

Has anyone Hit a number over 15K? If not you should set the limit to 15K and call it good. Set it at 15.5K and someone will find a cheap way to get there.


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"Merciless" Mitch Eaves
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Jimbo
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Post by Jimbo »

Mitch we don't want to end up with the same situation as the SSC planes. When it gets cool and dry the engines may tach higher and get very near the 15.5 limit. We should know more in a few months.

Limited-B
Try it,you'll like it !
Bad Dawg
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Post by Bad Dawg »

Two notes,
1) I wishI could get mine to tach to 14.5K
2) The idea of having a pile of MA 10x4's or APC 10x3s and a pile of stock mufflers (as per Drew's idea)at a contest has merit. I am not for "gentleman's agreements", and to have an open B contest that is flown under conditions that are very different than other contests would sort of make NPS meaningless. But I sure like the speed of Limited B.

NUNC AUT NUNQUAM
Mark V.
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Post by Serg »

First of all: Mark, thanks for organizing limited-B demo on Montrose.
My conclusion is: OS-max-25fx in good stand with stock muffler and 10x3 propeller just a little bit slower than regular open-B.

Finally my opinion is:
Creating more and more classis is not right way to make sport more popular.
(It has negative effect. Too many deferent directions cause additional divergence)

Introducing new and new restrictions in the existing rules also not correct way according my view.
Sport history gives us simple example: Only one goal exist – goal to be better. This is only one reason for any evolution. Making any restriction you do stop evolution.
Bad Dawg
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Post by Bad Dawg »

I dissagree about the history of sports, Serg. Thre are more and more restrictions in almost every sport, every year.

I agree that more classes are not a good thing. I would prefer greater restrictions on B and 2610 and have all of our energies go into promoting only two classes.

Since RC Combat isn't growing the way many of us would like it to, we are searching for the best combination of combat plane traits to please the most (certainly not all) RC pilots.

NUNC AUT NUNQUAM
Mark V.
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Post by sgilkey »

Brian and I finally got out and did some more testing. Day was 70-ish temps, low humidity, fuel was two jugs, one 10 and one 15%, combined to give 12.5% (using up leftovers). No optimizing for glow plug, etc.

MAGNUM .25 XL
9x4MA 16.5 (ref: with MCP 17.5)
10x4MA 14.1
10x3APC 14.3

ENYA SS25 BB
9x4MA 15.8 (ref: with MCP 17.2)
10x4MA 13.9
10X3APC 14.0

Both engines ran very nicely. Though the Enya had disappointing static numbers, the in-air performance was surprisingly good! I think this may be because it has a teeny tiny carb which gives excellent fuel draw- the Enya didn't miss a beat and pulled very well through the turns and climbs. The speed difference to the Magnum was minimal, despite the difference in static rpm.

As a side note, the Enya really picks up rpm with a MCP. However, the needle goes from having a smooth, linear response to being hair-trigger sensitive. I don't think it was particular to this engine as I have two Enya SS25s and both have the same behavior- there must be something odd in the port timing of this engine that interacts with a tuned muffler to make the needle range very narrow. I did not fly the engine with the MCP. Overall I expected to be disappointed in the Enya and ended up liking it.

We didn't have time to try it, but I want to do an experiment- if someone else has a chance, I think it would be instructive. I would like to have two nearly-identical Limited B ships flying at the same time, one with an engine turning about 800 rpm lower than the other (per static rpm check) and see what the in-air performance difference is. In SSC, 1000 rpm makes a very significant difference, 1000 as a ratio to the 17.5k peak would translate to about 800 rpm off the rpm we are seeing with the LimB engines so far. I am curious to learn how significant it would be for LimB. My hunch is it would have a lower effect on overall performance than with the lower-thrust SSC ships. Objective of this experiment is to see how critical rpm is for this event, and whether we need to be concerned about folks figuring out how to get their engines up to the 15.5k max. My guess is even if you are 800-1000 rpm down, you will still get competitive performance, but I want to try it. Or see someone else try it!!!



Scott Gilkey
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Post by BigCountry »

Scott,

During the last formal demo we held at LARKS field over Labor Day Weekend we had something very similar to what you're describing. We had Jared and Myself flying WASP's and Charles and Tony flying Slashers. Now Tony's 25fx was turning right up there with Jared's 28F and my 25fx but Charles Norvel was every bit of 5-600 rpms below any of us and when you put the planes in the air there was very little discernable difference. Charles' Slasher was right in there with us in turning and forward speed for the most part.

We have been noticing these differences don't exactly equate to big time advantages in the air. Now I know that ThrustHP will indicate differently but we just have not seen that 5-600 rpms make a huge of a difference when it comes to flight time.

Maybe Doc Evil can find a similar comparison in Waverly this weekend. Thanks for the additional data Scott and Brian...

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Hat Trick
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Post by Hat Trick »

I'll give it a shot. I think to make a real comparison you need to fly them one on one and do some straight and level passes and see which can do tighter sustained loops etc.
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