The Murphy Builders Site

I remember he told Jack to move it back 2" for the O-290 (which

turned
out to be heavier than an O-320 ...).

I was told to move mine back 1 1/2" for an 0-290. I asked how far if I

a lightweight starter,alternator and a warp drive prop. Then I was told
that should be OK with the firewall where it is.
Drew





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I just didn't ask, like the rest of the airplane, when I did mine! ) LOL

No reason IMHO to cut the firewall back at all. The extra "stress load" of
the engine being out 3" more, when it's already over 3 feet out from the
door posts, isn't going to make a tinkers damn when it comes to shearing
door post rivets/crumpling lower corner wraps/etc.

C of G range for the wing is 7.7 to 19.7"...even though the "operating"
range was changed in later documents. Anything you load into a Rebel moves
the C of G back...thus the more forward the empty C of G is the more you
can
load into the back and stay inside the envelope. I'd rather have a nose
heavy Rebel and carry a 5 gallon jug of water lashed down in the back when
flying solo/test flying etc...than having an EMPTY C of G way back around
the 14"+ mark like many 912 powered and firewall cut back O-320's are
flying
at...limiting their cargo loads considerably. You can also drink
water...but
U can't eat lead (at least not for long)!

Mine flys like a dream on wheels/hydraulic skis and now this summer on
Amphibs.

To give an idea of working numbers my empty weight:

on wheels.... with three fully adjustable seats, O-320, Warp Drive prop,
Alum flaperons (and their 16 lb c/balance penalty), full size Gill - 25 in
the tailcone (moved only in preparation of float install - was fine on
firewall for wheels with empty c of g = 10.2" AD), hydraulic system for
amphibs, full paint, upholstery, moulded headliner, Die spring compression
struts, Scott 3200 tail wheel, etc....Empty weight = 999lbs and empty C of
G
is 13.2" Aft of Datum

on Hydraulic Wheel Skis...same stuff as above + the skis/hyd lines/etc
Empty weight = 1104lbs C of G = 11.18"

on MAM 1800 Amphibs...same stuff + amphibs, 12 feet total length of
extruded
step, dual paddles/holders, wheels full of grease, etc Empty 1201lbs C
of
G = 12.76

In all configurations mine flies like a dream. I came home on amphibs this
morning at about 1700 lbs. I left glassy water in 8 seconds, climbed out
at
850 fpm @ ~ 45 MPH, cruised at 2475 doing 82Knots in no wind. Floats are
mounted 3* "throat" in relation to the cabin bottom. Note she flies faster
on Amphibs than when on the hydraulic skis !!

Howard's CYP has an empty C of G of about 9.7" AD. When low on fuel and
solo
needs to be "flown" onto the water...but not an issue. A gallon of water
in
each rear float compartment...like I did with FOKM when flying solo and
below half tanks...works like a dream for enabling you to hold the nose
wheels off the runway until you come to a crawl when landing.

Bob P's XWI after the O-320 replaced the Subaru..along with installing a
42
lb Sensenich prop weighed in with an empty C of G around 7.9" AD if I
remember correctly. Had to be careful on the brakes when solo and low on
fuel...but one heck of a rocket. When mounted to 1800 amphib floats (that
have an empty C of G of their own around 11.8") this will move his back to
around 9.5 to 10" and may require some slight H2O ballast for solo work
(to
hold the nose wheels off)...but will open the door for over 450 lbs of
baggage capability (read 1/2 a moose) before getting even close to the
rear
19.7 limit.Mine @ an empty CofG of 12.76" can have 385lbs in the baggage
area before going out the rearward limit when down to 45 minutes fuel and
solo.

Enough rambling...just thought these might be some useful #'s !

Cheers,
Wayne


----- Original Message -----
From: "Drew Dalgleish" <drewjan@cabletv.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, September 07, 2005 9:48 PM
Subject: Re: Engine Choice

I remember he told Jack to move it back 2" for the O-290 (which

turned
out to be heavier than an O-320 ...).

I was told to move mine back 1 1/2" for an 0-290. I asked how far if I

used

a lightweight starter,alternator and a warp drive prop. Then I was told
that should be OK with the firewall where it is.
Drew





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