Limited-B Rules ( as of now )

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Jimbo
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Limited-B Rules ( as of now )

Post by Jimbo »

I know this is a repeat but here it is.The only thing that would be different than Open B is..........
1.)Flying weight(dry)shall be no less than 3lbs.
2.)Maximum Engine .28cid
3.)Prop must be an APC10x3 (Travis is going to call them about changing its color.
4.)Maximum RPM's will be no more than 15.5K at full open throttle at leanest setting.
5.)Engine must have an expansion chamber muffler. NO type of tuned exhaust are allowed.

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

Purpose for Limited B class:

What goals are we trying to achieve with the creation of a Limited B class?

<ul>1. Reduce the amount of carnage that takes place in Open B combat<li> </li>2. Keep as much of the excitement level of Open B as possible<li> </li>3. Reduce Open B speeds thereby increasing the possibility of attracting new combat fliers.</ul>
The purpose of the Limited B class is not to replace Open B as a class nor to change it in any way. Open B has always been and will always be the biggest adrenaline rush to be found in combat. Limited B is designed to extend the lives of the combat aircraft given new building techniques and materials as well as enticing prospective new combat fliers or the old combat flier who likes the performance a .25-.28 sized motor can offer. It is built upon the success of the SSC class and is meant to offer combat fliers a choice in how they choose to slow down their combat.


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Lou Melancon
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Post by Lou Melancon »

Jimbo & Travis,
That's a good start. Keep us all informed and up to date about when and where demo events are scheduled.

Lou Melancon
Alpharetta, Georgia
BigCountry
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Post by BigCountry »

<b>Here is what Jimbo just said in more detailed terms. This will be used as the actual rules structure</b>

Proposed rules for a Limited B class (proposed provisional class), originated July 26, 2004 for the remainder of the 2004 contest season.

1. With the exception of the following requirements, all RCCA B-Class rules and scoring will be used.

2. Engine: Stock up to .28 cid engine. The engine and carburetor must not be altered from factory or stock condition. Only modifications listed below will be allowed. Engines used must be classified by the manufacturer for use in flying R/C Aircraft. The engine must be complete with the stock carburetor free of modification as well as a muffler that is cataloged for the engine by the engine manufacturer. The carburetor must be fully functional via servo operation and capable of performing as intended.

Allowed engine changes:

a. Any or all external engine bolts may be exchanged for bolts that are either of better quality or cheaper cost.
b. Any “stockâ€
BigCountry
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Post by BigCountry »

I know there will be numerous valid suggestions for changes to the above posted rules. The great thing is that we can change these rules as many times as we like. The key I think is that we suggest changes based on what we see from the demonstration events that are held. At this point I think that is the key to pushing this forward is to get to holding demonstration events. Ideally I'd love to see one held in each of the districts but that's probably wishful thinking on my part but if anyone is willing to hold a demonstration event that will help us tremendously as we need to have held six by the end of the year. The only criteria for a demo event is there must be four RCCA members participating. They do not need to take place in conjunction with any other event or be scored or sanctioned. The only thing that we would ask is that you report your groups reaction from the event so that any changes to the rules can be discussed based on what was discovered. Anyone that would be willing to hold a demo event(s) please contact me off the forum so that we can keep track of who's holding the events and when. Thanks everyone for all your input to this point...

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Feathers
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Post by Feathers »

There is an SSC combat meet in Grand Rapids, MN. this weekend and we have plans to try some limited B combat Friday night. We have five RCCA members planning to fly (maybe more?). Any chance we can count it as a demo?

Scott, I felt like the 10x4 MA really built up speed in the dives and struggled in the up lines. Perhaps this is a .25FX phenomenon? I have a bunch of 10x4 MA’s that I’ll pass around for guys to experiment with. Perhaps we can get some more opinions? I agree that the APC is a little brittle and also lost one on a landing that should not have cost me a prop. However, I sure liked the way it flew the plane…..



Tim Feathers
Wild Wings Combat
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Jimbo
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Post by Jimbo »

When doing testing keep in mind you should fly as you would in combat to get a real feel for it. This may just be my style but I don't do a lot of prolonged dives because I don't like to fly very high anyway. Just something to think about. Thanks to all of you for helping.

Limited-B
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BigCountry
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Post by BigCountry »

Tim,

If there will be five or more of you participating I don't see why that can't be counted as demo #1 and counting. Please post a mini-debrief here under the Provisional Section under another topic so that we can start tracking the response to the idea in general and the rules structure as we've got them laid out. Thanks for stepping up to the plate and getting us going...

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Rabbit Leader
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Post by Rabbit Leader »

Big, Jimbo, I like what I'm seeing. I think ya'll have a really good shot at making this thing work, and I'll give you whatever help I can as far as data, etc. I would be real nice to have 3-4 scale birds and 3-4 open birds to start off the year and have a reasonable chance of being able to keep the same fleet going throughout the year. JP and I were talking about this tonight..sure, we're gonna see some damage, that's part of the game, but I sincerely belive that, 90 percent of the time, it will be repairable damage, as opposed to rebuildable or total loss damage. I think we need to keep the lines of communication open between all of us, also. Keep it up, guys!!

Cash

"Furballs are for cats!"
BigCountry
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Post by BigCountry »

Without a doubt Cash, anything we can offer to the 2548 movement we will do so and I know that conversely if we need anything we have your support as well. Right now we need to switch gears to demo mode and start conducting some demos. If Tim and his group are able to make theirs happen Friday evening we'll definitely be off to a good start.

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sgilkey
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Post by sgilkey »

Those rules look great to me, let's adopt them and go fly!!! I detest rpm limits but fear they are a necessary evil for this type of class, I sure wish we could do without them though. I still much prefer the MA 10x4 as why do we want to set ourselves up for breaking props frequently, I agree they fly better but the objective is limiting performance afterall and APC breakage is a nuisance, i spend hours of shop time just balancing props by the dozen (yes I hate it but feel is it a necessary evil to avoid fuel foaming, etc). I assume since you mandate "stock carb" but then allow carb swapping, that you just mean the carb has to be unaltered, i.e. bored out, spraybar cut off, etc, but by these rules i could put a ST carb on a Magnum, an OS 32 carb on a 25FX, etc. I feel this should be allowed especially since we have the rpm limit. I like the muffler rules and assume by their wording that reamed tailpipes (or even broken off ones) are acceptable, we are just avoiding internal pipes?? Overall, looks great!! thanks!

Scott Gilkey
Cajun
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Post by Cajun »

One quick question. Does the carb barrell have to be full open when doing the tach.

My suggestion is YES. I don't like to tach an engine with the barrell 3/4 open.[:(]

I don't wish to start this off with some controversy, but it will come up and just as well define it now.[:)]

CAJUN [8D]
Lone Star Combat State
AMA-CD 174052
RCCA 380
NACOGDOCHES, TEXAS
MY MIND WORKS LIKE LIGHTNING,,ONE BRILLIANT FLASH AND IT'S GONE!!
Jimbo
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Post by Jimbo »

Rule number 4 on my first post.

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

Bill,

That's my fault, I didn't get the wording corrected before posting it last night but as Jimbo mentioned it will be there. Very good catch though, I tried to proof my wording but it's difficult so stuff like that needs to be brought up. I'm certainly not an English major so things like wording or grammar issues or omissions please bring up now so they can be corrected.

Scott,

You're correct on each of your questions. With an RPM limit in place we can allow the other items. I have a OS 32sx carb on the 25fx that we tested last weekend and while definitely stronger than Jimbo's Irvine it still didn't come close to busting out...

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Admin
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Post by Admin »

I’ve had a couple thoughts while reading this development. They may be useful, may be a waste of bandwidth, you decide... [8D]

1) Larger diameter props have stronger hubs. Stronger hubs keep chomping longer on other planes before they break. A 10x5 MAS on a .40 will chop through rods, fuses, and radio gear. Granted, .25’s won’t have the torque of a .40, but keep this in mind as ya’ll work towards a spec prop. A weaker prop may not be such a bad thing.

2) Limited power will send innovators to work cleaning up drag. Less drag, more speed. The quickest way to do this is with thinner airfoils. Thinner airfoils lead to weaker wings and more fatal damage. A minimum wing thickness limits drag reduction and durability.

3) Higher aspect ratio wings are more efficient. To achieve higher aspect ratios, wing chords are reduced, spans are increased, and wing survivability suffers. A max span and wing area range would head this off at the pass.

4) The closer you are to the RPM limit the better. The tighter you can turn, the more fuel pressure is required to maintain the correct fuel mixture. Stock mufflers have limited muffler pressure especially with the baffles removed. A pressurized system will have an advantage. I know the Bladder Police will be here any minute, but I suggest eliminating pressurized fuel systems.

5) I suggest taking a look at www.nmpra.org under the rules section or in the AMA rulebook under pylon. These have been around for a long time and refined a bunch. A good place to start may be here:

http://www.nmpra.org/Aprarules/Aprarules.pdf

(The pylon rules aren't perfect and a couple loopholes have been exploited and have voided the original intent. Don’t make the same mistake.)

6) Set your targets low. Meaning if ya’ll decide 65 mph is a good speed. Shoot for RPM/pitch numbers that are lower, lets say 60 mph. Technology will march on and speed creep will be inevitable. Folks will always figure out a way to squeeze more performance out. Account for this up front and there shouldn’t be a problem.

7) Get as much of the bigger changes nailed down as soon as possible. The more time goes by, the harder it will be to make changes.

Finally, a good objective needs to be developed. An objective used to judge a proposed rule change with the following question, “Does this support the intent of this class as defined by the objective.â€
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