[SPAM] Re: SPAM Re: Rules Survey

Tue Feb 8 19:09:38 AKST 2005

Bill,

When it comes to this topic, a lot can be learned from the history of the event.  The limiting can be done with weight, displacement, or dimensions.  The 5 or 10% of top competitors/designers/innovators have always aggressively pushed right to one or more of the limits - and the majority of others in the event follow as fast as they can afford to - that is the very nature of competition.  Without going into a comprehensive review of historical rule changes and the effects, I'd strongly suggest the best way to limit size/expense is with displacement (of course electrics throw a big wrench into that one).  Simple FACT - Without exception, every single time a limit has been removed or raised, the average cost of the plane on the flightline at a pattern contest has gone up.

For a long time, the 2x2m limit was meaningless because it wasn't the factor that limited the size of the planes.  The 2x2m limit has a limited impact (and no, that is not a CompArf Impact on a diet) on the size of the planes today - most are at 2m length, but few are at 2m wingspan. For a long time, the displacement was the only real limit - and when that was recklessly thrown away, the planes got bigger (and more expensive) in response to the available power.  Now the limiting factor is weight.  Throw that away (or raise it) and the planes will get bigger again (and more expensive).  How much bigger?  Depends on how high the weight limit is raised.

At 12 lbs - The guys that don't build light will have the same stuff that is marginally over 11 lbs.  And some guys will stuff Moki's into pattern planes and find out they don't fly really well with heavier engines that they were not designed for.  And both will be at a disadvantage because you will see some HUGE monoplanes with DA50s that make the current day stuff look infinitely affordable.  Double Vision Bipes that are not fragile will be easy to do (an a major PITA to transport back and forth to the field, assemble, maintain, etc).  Fragile bipes bigger than the Double Vision will arrive on the seen.  Under Chips watchful eye, I put a few minutes on one of the Double Vision Bipes a while back - maybe it isn't an advantage in Sportsman, Intermediate, Advanced, or even Masters.  But in a sequence full of rolling circles, rolling loops, and integrated loop/roll segments, it is an advantage (as long as the horsepower is available, which it would be if the weight limit went up).  And what wins the top class, is what the majority will shift to.  The reason the Double Vision has not caught on more in pattern yet, is because the plane is fragile at 11 lbs, and it does require a strong powerplant to adequately power the plane (especially at 94 db).

If no weight limit - How about a 30% Ultimate style Bipe - give or take 70" span, 78" long, 1700 squ, and maybe 20 lbs???  Anyone who doesn't have a deeper checkbook, full sized stretch van or model model trailer, and model trailer will be at a disadvantage.  Check some IMAC kits - the numbers jive.  Minimally you will be adding 4 more servos (to maintain pattern standards of servo power to surface), and a monster cost increase in engine, muffler, softmount, prop, spinner for your DA50 or GT80 twin.  Increased cost of the kit, building, transporting, setup, and maintenance should be obvious enough.

Something that I think that has been overlooked in this thread is the "fourth" limiting factor in our event - noise - 96 db for AMA, 94 db for FAI.  In my opinion, 94 db is the real number because any manufacturer who wants to sell to the pattern market is going to want to be able to market/target FAI.  Displacement unchecked equals more noise.  Heavier planes require more power which equals more noise.  Unless of course additional money is spent on exhaust systems to keep things quiet.  And more and more the prop noise is diminished by going to 3 or 4 blade props (quieter, but less efficient, so now more power is needed again).  Very few large displacement sport engines (gas or glow) are equal to or quieter than a pattern setup (and most YS DZs running in their power band are also above 94 db) because of the larger displacement and larger diameter prop (increased tip speed).  Add up the costs for the quality exhaust systems, softmounts, and props to keep the DA50 quiet and I think you'll find a 140RX to be quite cheap.

Regards,

Dave Lockhart
DaveL322 at comcast.net

----- Original Message ----- 
From: "Bill Southwell" <bnbsouthwell at bellsouth.net>
To: <discussion at nsrca.org>
Sent: Tuesday, February 08, 2005 11:47 PM
Subject: [SPAM] Re: *SPAM* Re: Rules Survey

> 
> 
> Hi Dave,
> 
>     How do you mean bigger plane? Are you refering  to a little more sq 
> in? Didn't the older designs during the fourstroke 120-140 change adapt 
> too the power and wt with a bigger wing? We can't go any bigger if the 
> 2M requirment is in play. I am not trying to be difficult but the wt 
> problem at least in my mind ( what a crazy place that is!) is that the 
> power plants are doing all they can do due to the airframe size. The 
> larger  slower turning  engines might cause some evolutionary changes 
> but  not a  huge change in airframe layout.  The airframes are optimized 
> for the 2M size  the engines are tapped out. No beef to them!   If the 
> power becomes  easy to manage $$$ and more  reliable to the average guy 
> then we have  more interest and  a lot more fun flying.  Another thought 
> ...My Moki' 1.80 on a 20" prop were pretty quiet with very little in the 
> way of a  muffler. The bigger disk made a great brake on down lines and 
> landings and the engine ran like a sewing machine. Change is good! 
> 
> 
> David Lockhart wrote:
> 
> >Bill,
> >
> >The current set of rules basically establish a performance level that is a
> >target to shoot for.  I believe you are correct in that the current
> >performance level might be easier to approach if a 12 pound plane were
> >allowed.  BUT - if the 12 pound plane is allowed, the performance level will
> >increase and you will be in the same situation then as you are now, but we
> >all will be paying for the added expense of the bigger plane - and the
> >planes will get bigger if the weight limit is increased - bigger planes do
> >fly better and competitors will seek that advantage.
> >
> >Regards,
> >
> >Dave Lockhart
> >DaveL322 at comcast.net
> >
> >----- Original Message -----
> >From: "Bill Southwell" <bnbsouthwell at bellsouth.net>
> >To: <discussion at nsrca.org>
> >Sent: Tuesday, February 08, 2005 9:56 PM
> >Subject: Re: *SPAM* Re: Rules Survey
> >
> >
> >  
> >
> >>Tom how so?  If there are available engines that actually hold up but
> >>are a bit more porky....but also a lot cheaper to own both in intial
> >>purchase and in up keep how can it lead to a more expensive airplane.
> >>Cost of the present designs are due to the materials and mathods of
> >>production required tokeep the weight down. A little more room would
> >>make more pedestrian material like balsa , ply. and foam to come back or
> >>at least make the average builder have hope.
> >>
> >>
> >>
> >>
> >>
> >>Tom Shaw wrote:
> >>
> >>    
> >>
> >>>You guys need to leave well enough alone.  With the unlimited engines
> >>>a higher weight limit is just going to ecourage larger more expenseive
> >>>airplanes.  That will amount to fewer flyers.
> >>>
> >>>    ----- Original Message -----
> >>>    *From:* Gray E Fowler <mailto:gfowler at raytheon.com>
> >>>    *To:* discussion at nsrca.org <mailto:discussion at nsrca.org>
> >>>    *Sent:* Tuesday, February 08, 2005 4:25 PM
> >>>    *Subject:* RE: *SPAM* Re: Rules Survey
> >>>
> >>>
> >>>    Here comes the dreaded weight debate again....
> >>>
> >>>    Consider this-Anyone in the upper level classes would not be too
> >>>    smart to have a plane heavier than it needs to be.  But, lets
> >>>    pretend there is a hot new Sportsman named uh lets see..... Chuck.
> >>>    Chuck tears up 401 after 3 contests, and he is flying his best
> >>>    airplane that most FAI guys would consider a toy (and I do not
> >>>    mean the "foamie toys" pictured in last months Model Aviation
> >>>    being held by  a guy named "Chuck")  and so moving up to
> >>>    Intermediate halfway thru his first season, last 3 contests were
> >>>    quite a challenge, BUT he places in 402 anyway!
> >>>    In the off season, he saves his pennies, keeps his wife happy and
> >>>    gets a used REAL pattern plane, built by someone who has a slight
> >>>    heavy hand, and alas it weighs 11.5 lbs. Now this here Chuck is
> >>>    good and pumped up and I would place money that this theoretical
> >>>    person could place at the NATS, but his plane is over weight!!!!!
> >>>    one more !
> >>>
> >>>    Sorry Chuck, even though you are flying at a disadvantage, we will
> >>>    not let you play at the NATS........Oh unless you can spend $2k
> >>>    more on another plane.
> >>>
> >>>    The story you have just read is about to be true, once we do not
> >>>    let Chuck fly at this years NATS. But at least the French FAI rule
> >>>    makers are happy.
> >>>
> >>>    Consider a weight change. It does not need to be across the board
> >>>    and for the life of me I cannot imagine why it needs to align with
> >>>    FAI.  Chuck will have a 5Kg plane *BY THE TIME HE REACHES FAI-*and
> >>>    the French can be happy then*.*
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>      
> >>>
> >>=================================================
> >>To access the email archives for this list, go to
> >>http://lists.f3a.us/pipermail/nsrca-discussion/
> >>To be removed from this list, go to http://www.nsrca.org/discussionA.htm
> >>and follow the instructions.
> >>
> >>    
> >>
> >
> >=================================================
> >To access the email archives for this list, go to
> >http://lists.f3a.us/pipermail/nsrca-discussion/
> >To be removed from this list, go to http://www.nsrca.org/discussionA.htm
> >and follow the instructions.
> >
> >
> >  
> >
> 
> =================================================
> To access the email archives for this list, go to
> http://lists.f3a.us/pipermail/nsrca-discussion/
> To be removed from this list, go to http://www.nsrca.org/discussionA.htm
> and follow the instructions.
> 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.f3a.us/pipermail/nsrca-discussion/attachments/20050209/427977ee/attachment.html