E=MC3

[Jerry Budd]

Hi Jeff,

The E=MC3 is an E=MC2 with a bunch of modifications that I decided to 
implement to try to improve the baseline design.  I flew a used E=MC2 
for several years that I had purchased from Kirk Sutherland in 
Tennessee.  It exhibited a number of good-to-excellent flying 
qualities, but like most airplanes there was still room for 
improvement.  Also, I was wanting an airplane that was reminiscent of 
the classic Pylon Racer designs such as the Cosmic Wind as I think 
it's distinctive and presents well, both on the ground, and in the 
air.  Here's the construction mod's:

1)  Raise the wing 2".  No, that's NOT a typo.  2".  During 
construction I also had the wing moved forward 3/4" (bad idea), but 
it came out nose heavy so I had it moved back 1-1/8" from there to 
get it to balance properly.  My recommendation is if you're using a 
4-stroke, don't move the wing either fore or aft from stock.  If 
you're running a 2-stroke motor like I am (especially if you tend to 
build a bit heavy) you may want to consider moving the wing aft 1/2" 
from the location shown on the plans.  The wing dihedral was left at 
the stock amount.  The next one I build will have the geometric 
dihedral reduced by 1/3 to attempt to eliminate the small amount of 
residual proverse roll coupling.

2)  3-1/2 degrees right thrust, 1/2 degree down thrust (I believe the 
stock E=MC2 design is 0-0).

3)  Replacement of the stock pipe channel with a custom one 
fabricated from carbon fiber that allows the ES pipe to be completely 
flush mounted.  The channel is extremely long, extending aft ~42" 
from the glow plug, allowing for unobstructed experimentation of 
tuned pipe system(s) set to almost any length.  I've given some 
thought to offering the pipe channel for sale in limited quantities 
as it can likely be used on a number of planes other than the E=MC2/3 
(for those that are interested, please send me an eMail and let me 
know.  If these is enough interest shown I may go ahead and have some 
fabricated).

4)  Small cheek cowlings that while functional, are largely cosmetic in nature.

5)  I had the ailerons and elevator halves fabricated so that they 
didn't fully extend out to the wing/stab tips.  While counter to the 
current trend, I like being able to visually check whether a warp has 
crept into a flight control surface.

6)  Since the wing was raised and the pipe tunnel deepened, I was 
able to use a one-piece Chris Dalby carbon fiber landing gear 
(available from RC Model Enterprises, 
http://home.att.net/~rc-enterprises/rcme_017.htm) mounted external to 
the main fuselage.  It's much thinner and lighter than the two piece 
carbon fiber gear, and also has a torsion effect in that it "gives" 
in the fore and aft direction similar to the way wing-mounted wire 
landing gear relieve under loading.

Did the mods work?  I think so based on my own observations and also 
the comments I've gotten from those who have flown it:

Tony Frackowiak - "easily the best pattern airplane I've ever flown"
Greg Frohreich - "you've fixed everything that was wrong with the 
E=MC2 design and made it a competitive airplane again", "it flies 
just like my Smaragd"
Troy Newman - "this is by far the best E=MC I've ever flown"
Frank Kelley - "this flies exactly like my HydeOut/Away

There's a link to some photo's of the E=MC3 on my website:

http://www.buddengineering.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=E


Thx, Jerry


>Jerry,
>I've seen a couple of references now to the emc3. I assume its a variation
>of Dick Hansons' emc2? What is the difference?
>Jeff
>
>
>
>----- Original Message -----
>From: Jerry Budd <>
>To: <discussion at nsrca.org>; <pattern at rcmailinglists.com>
>Sent: Sunday, March 30, 2003 2:17 PM
>Subject: Re: [Pattern] 3M-140 For Sale
>
>
>>  >Hey Jerry,
>>  >    which engine do you prefer: the OS1.40RX or the Webra 1.45? Why?
>>  >    Thanks,
>>  >      Will B.
>>
>>  Hi Will,
>>
>>  I like the Webra a bit better than the OS but they both have their
>>  merits.  I'm running them interchangeably in the same airplane
>  > (E=MC3) on Magnum #1, OS-F or YS plug, ES-2C140L90 pipe set at
>>  23-1/4" baffle to plug, stock Mac's 2-1/4" rise header, and an APC
>>  17x12 prop.  Here's the differences:
>>
>>  Webra:  8200-8300 rpm with the Webra MC (mixture control) carb gives
>>  a dead linear throttle response with NO jump onto the pipe.  Setup
>>  this way the motor performs and throttles exactly the same as a DZ.
>>  With the stock ProMix carb it throttles a lot like the OS (see
>>  below).  This is with a relatively new, low time motor (~20 flights).
>>
>>  OS: 8300-8400 rpm with the stock OS carb, slight burble at mid-range
>>  transition, moderate jump onto the pipe around half throttle.  The
>>  motor goes slightly lean momentarily during inverted pushes during
>>  the second half of the 20 oz tank.  My first OS in the same airplane
>>  exhibited the same characteristic.  This is a motor with around 30
>>  flights on it.
>>
>>  The OS carb has a somewhat bigger throat than the Webra carb which
>>  probably explains the power difference, but may also cause the
>>  throttle linearity/burble/momentary lean discrepancy.  The OS also
>>  seems to have significantly more bearing problems, although that
>>  seems to be corrosion related and managed by switching to stainless
>>  steel bearings.
>>
>>  I think the 3M-140 motor is comparable to an average OS in power, but
>>  it throttles much better in the mid-range.  It would make an
>>  excellent motor for a 9.75-10.5 lb mid-body airplace such as a Focus,
>>  Temptation, HydeAway, Angel's Shadow, etc.
>>
>>  Thx, Jerry
>>  --
>>  ___________
>>  Jerry Budd
>>  mailto:jbudd at qnet.com
>>  =====================================
>>  # To be removed from this list, send a message to
>  > # discussion-request at nsrca.org
>>  # and put leave discussion on the first line of the body.
>>  #
>>
>>


-- 
___________
Jerry Budd
mailto:jbudd at qnet.com
=====================================
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