[rebel-builders] Rebel - Should you move your firewall back 3
Posted: Sun Feb 19, 2012 11:38 am
WRT Daryl's letter,
I understand the efficiency gained by having a CG toward the aft of the
envelope, but the second loading example with the CG BEHIND the CP seems
extreme. I thought you had to have some down load on the tail to maintain
pitch stability, unless it's a fly-by-wire fighter where the computer makes
the elevator move 100 times a second just to fly level.
What Daryl talks about with the tail contributing to the wing lift, seems
like canard theory, only we're not flying backward.
I only have a basic theoretical understanding of this, and maybe some
airplanes have safe CG ranges in this realm, but is a CG of 18" on the Rebel
really AFT of the C of P?
Anyway, I'm not going to cut my firewall back, it seems like just using a
light prop is easier and better. Oh, and use thicker corner wraps.
Jesse
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I understand the efficiency gained by having a CG toward the aft of the
envelope, but the second loading example with the CG BEHIND the CP seems
extreme. I thought you had to have some down load on the tail to maintain
pitch stability, unless it's a fly-by-wire fighter where the computer makes
the elevator move 100 times a second just to fly level.
What Daryl talks about with the tail contributing to the wing lift, seems
like canard theory, only we're not flying backward.
I only have a basic theoretical understanding of this, and maybe some
airplanes have safe CG ranges in this realm, but is a CG of 18" on the Rebel
really AFT of the C of P?
Anyway, I'm not going to cut my firewall back, it seems like just using a
light prop is easier and better. Oh, and use thicker corner wraps.
Jesse
_________________________________________________________________From: Drew Dalgleish <drewjan@cabletv.on.ca>
Reply-To: <rebel-builders@dcsol.com>
To: <rebel-builders@dcsol.com>
Subject: Re: [rebel-builders] Rebel - Should you move your firewall back 3
Date: Tue, 30 Jan 2007 00:07:31 -0500
Yup It's easy to fix a forward C of G but not so if you're too far aft. My
most rearward loading is 17.66" without the firewall moved. I have a full
floor so if I really wanted to do math before each flight I could almost
always fly at the idea C of G. Daryl you say that 18" is well within the
envelope but the pilot operation manual you sent me gives the aft limit as
18.1"
At 11:27 PM 1/29/2007 -0500, you wrote:comingTypical FULL loading usage on mine going up to the lake (44 gallons fuel,
me, flight bag, clothes, couple of 5 gallon cans in back to top for3back home, tools, misc construction material, etc), on 1800 amphibs, puts
the operating C of G @ ~17" for a nice effortless/trimless cruise. Light
Warp drive prop, lightweight starter and O-320 Lyco on original firewall
positon. I did put my battery down the tailcone to be sure prior to the
float install...but I shouldn't have bothered as it would have been just
fine left on the firewall and when flying light a gallon of water in each
back float compartment would have fixed the nose heavy issue for me.
I also know it will recover from a spin...first I ever did with it in 10
years.....had to cork screw down thru a "hole" in August!
----- Original Message -----
From: "Walter Klatt" <Walter.Klatt@shaw.ca>
To: <rebel-builders@dcsol.com>
Sent: Monday, January 29, 2007 10:55 PM
Subject: RE: [rebel-builders] Rebel - Should you move your firewall backgWhen on amphibs, and even with the firewall cut back, hard to get much
more
than 13 c of g at 1730. But if you were to load it to 2000 (not saying
that
anyone does), that would also allow for some baggage, getting the c ofcourse,back to past 16, which is still well within the c of g. Again, that is
with
my 10.7 c of g empty amphib 0320 Rebel.
Best to use an excel spreadsheet to play around with different weights.
I like the idea of saving 80 pounds of wing lift by moving the c of g
back,
and also reducing/reversing the tail stress at the same time. Ofbackthat doesn't mean that the extra weight is free. Gross weight is still
gross
weight.
Walter
takesclonehavetheofftheIloaded.aboutBiggestthatwash.912SownIthesometimesleaninghavehavedetailedallRebel.LOTlongermorehave:-)Drew
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