The Murphy Builders Site

Hi Rick

Good to see that the Cheeze Grater is back on line ;-)

I don't have a cuffed airplane but, I'll take a crack at this just for fun.

1) The C of G should move forward my an almost unmeasurable amount - that is the (static) weight added by the cuffs will probably be added ahead of the previous C of G therefore moving it forward. I think you actually meant the centre of LIFT and it should move forward in proportion to the amount of wing area you added since the area added would be in
front of the previous C of L. I doubt that it would be a linear (with area) increase either since different parts of the wing contribute varied amounts of lift for a given area. Bottom line you may be able to lose some of that "balance enhancing mass".

2) Range of C of G. I think you're looking for an allowable C of G range increase and I think you're correct due to the added chord length. Since this is the first application of this design on this airframe you can now call yourself a test pilot! That'll be good for bragging at the pub!

3) You'll probably enjoy better low speed handling but as in 2), you'll have to do some testing to see how it turns out. Stalls may be different in nature from before.

Hope that rambling was useful!

Cheers,

Dave

Rick Harper wrote:

G'day from OZ Everyone !

We have just rebuilt our REBEL & received our new C of A & are just about to embark on a new flight test program to asses the planes' new handling characteristics with the leading edge cuffs that a friend (aircraft design engineer ) and I have installed - YAY !!!!!!!!!!!!

We'd really like a bit of input from those who have leading edge cuffs already fitted to their plane (Rebels or not) - as to what to expect / what the cuff did to :

1) The Centre of Gravity - ( did it move Fwd or Aft ? )

(my Neanderthal logic estimates that as the leading edge moves forward - the Centre of Pressure should move forward also (there's more wing chord / & area now) ... and therefore the C of G should move forward slightly - ( to keep in with the "most wings / planes will balance at about 1/3rd chord back from the Leading Edge" rule ) also ... Yes ?)

If that is so ..... then I reckon we should be REMOVING some of the 10Kgs of lead shot I have placed in the tailcone area ( to balance the "light weight" IO-320 with a NOT shortened firewall) ... Yes ???

2) The RANGE of C of G - (did it get bigger / smaller - or stay the same & move forward overall or aft overall)

3) Any salient points to keep an eye out for ?!?

AS always - your thoughts and opinions are gratefully received !

Biggus
541R

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G'day Dave !

Great stuff - thanks for the input

How's your beast coming along ???

Big
----- Original Message -----
From: Dave Ricker
To: rebel-builders@dcsol.com
Sent: Wednesday, January 31, 2007 10:40 AM
Subject: Re: [rebel-builders] C of G change advice


Hi Rick

Good to see that the Cheeze Grater is back on line ;-)

I don't have a cuffed airplane but, I'll take a crack at this just for fun.

1) The C of G should move forward my an almost unmeasurable amount - that is the (static) weight added by the cuffs will probably be added ahead of the previous C of G therefore moving it forward. I think you actually meant the centre of LIFT and it should move forward in proportion to the amount of wing area you added since the area added would be in
front of the previous C of L. I doubt that it would be a linear (with area) increase either since different parts of the wing contribute varied amounts of lift for a given area. Bottom line you may be able to lose some of that "balance enhancing mass".

2) Range of C of G. I think you're looking for an allowable C of G range increase and I think you're correct due to the added chord length. Since this is the first application of this design on this airframe you can now call yourself a test pilot! That'll be good for bragging at the pub!

3) You'll probably enjoy better low speed handling but as in 2), you'll have to do some testing to see how it turns out. Stalls may be different in nature from before.

Hope that rambling was useful!

Cheers,

Dave

Rick Harper wrote:

G'day from OZ Everyone !

We have just rebuilt our REBEL & received our new C of A & are just about to embark on a new flight test program to asses the planes' new handling characteristics with the leading edge cuffs that a friend (aircraft design engineer ) and I have installed - YAY !!!!!!!!!!!!

We'd really like a bit of input from those who have leading edge cuffs already fitted to their plane (Rebels or not) - as to what to expect / what the cuff did to :

1) The Centre of Gravity - ( did it move Fwd or Aft ? )

(my Neanderthal logic estimates that as the leading edge moves forward - the Centre of Pressure should move forward also (there's more wing chord / & area now) ... and therefore the C of G should move forward slightly - ( to keep in with the "most wings / planes will balance at about 1/3rd chord back from the Leading Edge" rule ) also ... Yes ?)

If that is so ..... then I reckon we should be REMOVING some of the 10Kgs of lead shot I have placed in the tailcone area ( to balance the "light weight" IO-320 with a NOT shortened firewall) ... Yes ???

2) The RANGE of C of G - (did it get bigger / smaller - or stay the same & move forward overall or aft overall)

3) Any salient points to keep an eye out for ?!?

AS always - your thoughts and opinions are gratefully received !

Biggus
541R

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Hi Rick

Well things on the build front have been faster, we've done virtually all but the fuselage up to the inspection point (about half of the first 90% right? LOL!) and that looks like a good point to move the pieces so we're planning on a new house shortly. Something about more space and a driveway without a hill. Remember that the stats show that the average
build requires two relocations before completion so we're still ahead of the curve!

The aviation fix has taken a slight detour as well with acquisition of a shiny new (to us) C-152 which will give Francine more seat time and me the chance to get my license (soloed so far). We'd been keeping an eye out for a while and another Elite builder introduced us to an RV builder who was close getting his project done and the rest is history (thanks
Ralph!)

The Elite will come up to speed again in due course and we'll have more seat time so it'll come out better for it.

Lots going on to provide distraction but we're keeping our eyes on the target.

Cheers,

Dave


Rick Harper wrote:

G'day Dave !

Great stuff - thanks for the input

How's your beast coming along ???

Big
----- Original Message -----
From: Dave Ricker
To: rebel-builders@dcsol.com
Sent: Wednesday, January 31, 2007 10:40 AM
Subject: Re: [rebel-builders] C of G change advice

Hi Rick

Good to see that the Cheeze Grater is back on line ;-)

I don't have a cuffed airplane but, I'll take a crack at this just for fun.

1) The C of G should move forward my an almost unmeasurable amount - that is the (static) weight added by the cuffs will probably be added ahead of the previous C of G therefore moving it forward. I think you actually meant the centre of LIFT and it should move forward in proportion to the amount of wing area you added since the area added would be in
front of the previous C of L. I doubt that it would be a linear (with area) increase either since different parts of the wing contribute varied amounts of lift for a given area. Bottom line you may be able to lose some of that "balance enhancing mass".

2) Range of C of G. I think you're looking for an allowable C of G range increase and I think you're correct due to the added chord length. Since this is the first application of this design on this airframe you can now call yourself a test pilot! That'll be good for bragging at the pub!

3) You'll probably enjoy better low speed handling but as in 2), you'll have to do some testing to see how it turns out. Stalls may be different in nature from before.

Hope that rambling was useful!

Cheers,

Dave

Rick Harper wrote:

G'day from OZ Everyone !

We have just rebuilt our REBEL & received our new C of A & are just about to embark on a new flight test program to asses the planes' new handling characteristics with the leading edge cuffs that a friend (aircraft design engineer ) and I have installed - YAY !!!!!!!!!!!!

We'd really like a bit of input from those who have leading edge cuffs already fitted to their plane (Rebels or not) - as to what to expect / what the cuff did to :

1) The Centre of Gravity - ( did it move Fwd or Aft ? )

(my Neanderthal logic estimates that as the leading edge moves forward - the Centre of Pressure should move forward also (there's more wing chord / & area now) ... and therefore the C of G should move forward slightly - ( to keep in with the "most wings / planes will balance at about 1/3rd chord back from the Leading Edge" rule ) also ... Yes ?)

If that is so ..... then I reckon we should be REMOVING some of the 10Kgs of lead shot I have placed in the tailcone area ( to balance the "light weight" IO-320 with a NOT shortened firewall) ... Yes ???

2) The RANGE of C of G - (did it get bigger / smaller - or stay the same & move forward overall or aft overall)

3) Any salient points to keep an eye out for ?!?

AS always - your thoughts and opinions are gratefully received !

Biggus
541R

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Fall River, Nova Scotia
Canada

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Yo Dave & Francine ! ....

Ha ! .... don't get too sidetracked on that spam can !
(and make sure you get a ride in a Rebel / Elite every now & then - just to remind yourself WHY you a building a "sport plane" rather than slugging it out with a slug !

..... When Greg (Gordon) came & asked me to take him for a run in the Rebel - he could not believe the difference in ground roll, climb out, handling, carrying capacity & stability that our Rebel had over his BELOVED "Traumahawk" (as we call 'em) / or Tomahawk as Mrs Piper calls 'em

Conversely, Greg took me for a run ( more of a fast walk actually ) in the "Trauma" one day ... and as we s.....l.....o.....w.....l.....y..... accelerated down the strip - I kept saying .....
"You know the Rebel would have been off & at 50', 100' etc' by now !"
- (and we almost did a 4WD excursion through the crap on the ground at the end of this strip too ...... thank Christ the farmer (who's strip we were on) cut down the trees in line with the runway - 'cause we went right through the middle of them !!! )
The Rebel by the way, was probably a few hundred feet over the top of those same trees when I flew out when I used the same strip later on -
(and I didn't have the advantage of a nice 5 knot headwind straight down the strip like Greg's Traumahawk had !!!)

Biggus


----- Original Message -----
From: Dave Ricker
To: rebel-builders@dcsol.com
Sent: Thursday, February 01, 2007 10:36 AM
Subject: Re: [rebel-builders] C of G change advice


Hi Rick

Well things on the build front have been faster, we've done virtually all but the fuselage up to the inspection point (about half of the first 90% right? LOL!) and that looks like a good point to move the pieces so we're planning on a new house shortly. Something about more space and a driveway without a hill. Remember that the stats show that the average
build requires two relocations before completion so we're still ahead of the curve!

The aviation fix has taken a slight detour as well with acquisition of a shiny new (to us) C-152 which will give Francine more seat time and me the chance to get my license (soloed so far). We'd been keeping an eye out for a while and another Elite builder introduced us to an RV builder who was close getting his project done and the rest is history (thanks
Ralph!)

The Elite will come up to speed again in due course and we'll have more seat time so it'll come out better for it.

Lots going on to provide distraction but we're keeping our eyes on the target.

Cheers,

Dave


Rick Harper wrote:

G'day Dave !

Great stuff - thanks for the input

How's your beast coming along ???

Big
----- Original Message -----
From: Dave Ricker
To: rebel-builders@dcsol.com
Sent: Wednesday, January 31, 2007 10:40 AM
Subject: Re: [rebel-builders] C of G change advice

Hi Rick

Good to see that the Cheeze Grater is back on line ;-)

I don't have a cuffed airplane but, I'll take a crack at this just for fun.

1) The C of G should move forward my an almost unmeasurable amount - that is the (static) weight added by the cuffs will probably be added ahead of the previous C of G therefore moving it forward. I think you actually meant the centre of LIFT and it should move forward in proportion to the amount of wing area you added since the area added would be in
front of the previous C of L. I doubt that it would be a linear (with area) increase either since different parts of the wing contribute varied amounts of lift for a given area. Bottom line you may be able to lose some of that "balance enhancing mass".

2) Range of C of G. I think you're looking for an allowable C of G range increase and I think you're correct due to the added chord length. Since this is the first application of this design on this airframe you can now call yourself a test pilot! That'll be good for bragging at the pub!

3) You'll probably enjoy better low speed handling but as in 2), you'll have to do some testing to see how it turns out. Stalls may be different in nature from before.

Hope that rambling was useful!

Cheers,

Dave

Rick Harper wrote:

G'day from OZ Everyone !

We have just rebuilt our REBEL & received our new C of A & are just about to embark on a new flight test program to asses the planes' new handling characteristics with the leading edge cuffs that a friend (aircraft design engineer ) and I have installed - YAY !!!!!!!!!!!!

We'd really like a bit of input from those who have leading edge cuffs already fitted to their plane (Rebels or not) - as to what to expect / what the cuff did to :

1) The Centre of Gravity - ( did it move Fwd or Aft ? )

(my Neanderthal logic estimates that as the leading edge moves forward - the Centre of Pressure should move forward also (there's more wing chord / & area now) ... and therefore the C of G should move forward slightly - ( to keep in with the "most wings / planes will balance at about 1/3rd chord back from the Leading Edge" rule ) also ... Yes ?)

If that is so ..... then I reckon we should be REMOVING some of the 10Kgs of lead shot I have placed in the tailcone area ( to balance the "light weight" IO-320 with a NOT shortened firewall) ... Yes ???

2) The RANGE of C of G - (did it get bigger / smaller - or stay the same & move forward overall or aft overall)

3) Any salient points to keep an eye out for ?!?

AS always - your thoughts and opinions are gratefully received !

Biggus
541R

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Hi Rick

Don't worry us about getting side tracked by a factory plane in fact I think it'll speed the process. House building may get in the way a bit though. I'm having fun working on my license and I'm looking forward to having a BRAND NEW plane when the Elite is done. The 152 is a nice little (and I mean little) plane to start with but if you remember I stand 6'-4"
so there isn't much room left for maneuvering with me and Francine in there! Good thing we're not both tall or wide. We stayed away from 172s because we didn't want to feel like we were stepping down (in size) to the Elite when it's done. Oh and getting rides in Rebels, there aren't any flying in our area so I haven't set foot in one since yours :o(

Heh heh, I can just picture you & Greg on a hot summer day (that's winter down there isn't it??) trying to get airborne, who was flapping their arms!?

Take care & let us know how the Rebel MkIII is working.

Cheers,

Dave


Rick Harper wrote:

Yo Dave & Francine ! ....

Ha ! .... don't get too sidetracked on that spam can !
(and make sure you get a ride in a Rebel / Elite every now & then - just to remind yourself WHY you a building a "sport plane" rather than slugging it out with a slug !

..... When Greg (Gordon) came & asked me to take him for a run in the Rebel - he could not believe the difference in ground roll, climb out, handling, carrying capacity & stability that our Rebel had over his BELOVED "Traumahawk" (as we call 'em) / or Tomahawk as Mrs Piper calls 'em

Conversely, Greg took me for a run ( more of a fast walk actually ) in the "Trauma" one day ... and as we s.....l.....o.....w.....l.....y..... accelerated down the strip - I kept saying .....
"You know the Rebel would have been off & at 50', 100' etc' by now !"
- (and we almost did a 4WD excursion through the crap on the ground at the end of this strip too ...... thank Christ the farmer (who's strip we were on) cut down the trees in line with the runway - 'cause we went right through the middle of them !!! )
The Rebel by the way, was probably a few hundred feet over the top of those same trees when I flew out when I used the same strip later on -
(and I didn't have the advantage of a nice 5 knot headwind straight down the strip like Greg's Traumahawk had !!!)

Biggus

----- Original Message -----
From: Dave Ricker
To: rebel-builders@dcsol.com
Sent: Thursday, February 01, 2007 10:36 AM
Subject: Re: [rebel-builders] C of G change advice

Hi Rick

Well things on the build front have been faster, we've done virtually all but the fuselage up to the inspection point (about half of the first 90% right? LOL!) and that looks like a good point to move the pieces so we're planning on a new house shortly. Something about more space and a driveway without a hill. Remember that the stats show that the average
build requires two relocations before completion so we're still ahead of the curve!

The aviation fix has taken a slight detour as well with acquisition of a shiny new (to us) C-152 which will give Francine more seat time and me the chance to get my license (soloed so far). We'd been keeping an eye out for a while and another Elite builder introduced us to an RV builder who was close getting his project done and the rest is history (thanks
Ralph!)

The Elite will come up to speed again in due course and we'll have more seat time so it'll come out better for it.

Lots going on to provide distraction but we're keeping our eyes on the target.

Cheers,

Dave

Rick Harper wrote:

G'day Dave !

Great stuff - thanks for the input

How's your beast coming along ???

Big
----- Original Message -----
From: Dave Ricker
To: rebel-builders@dcsol.com
Sent: Wednesday, January 31, 2007 10:40 AM
Subject: Re: [rebel-builders] C of G change advice

Hi Rick

Good to see that the Cheeze Grater is back on line ;-)

I don't have a cuffed airplane but, I'll take a crack at this just for fun.

1) The C of G should move forward my an almost unmeasurable amount - that is the (static) weight added by the cuffs will probably be added ahead of the previous C of G therefore moving it forward. I think you actually meant the centre of LIFT and it should move forward in proportion to the amount of wing area you added since the area added would be in
front of the previous C of L. I doubt that it would be a linear (with area) increase either since different parts of the wing contribute varied amounts of lift for a given area. Bottom line you may be able to lose some of that "balance enhancing mass".

2) Range of C of G. I think you're looking for an allowable C of G range increase and I think you're correct due to the added chord length. Since this is the first application of this design on this airframe you can now call yourself a test pilot! That'll be good for bragging at the pub!

3) You'll probably enjoy better low speed handling but as in 2), you'll have to do some testing to see how it turns out. Stalls may be different in nature from before.

Hope that rambling was useful!

Cheers,

Dave

Rick Harper wrote:

G'day from OZ Everyone !

We have just rebuilt our REBEL & received our new C of A & are just about to embark on a new flight test program to asses the planes' new handling characteristics with the leading edge cuffs that a friend (aircraft design engineer ) and I have installed - YAY !!!!!!!!!!!!

We'd really like a bit of input from those who have leading edge cuffs already fitted to their plane (Rebels or not) - as to what to expect / what the cuff did to :

1) The Centre of Gravity - ( did it move Fwd or Aft ? )

(my Neanderthal logic estimates that as the leading edge moves forward - the Centre of Pressure should move forward also (there's more wing chord / & area now) ... and therefore the C of G should move forward slightly - ( to keep in with the "most wings / planes will balance at about 1/3rd chord back from the Leading Edge" rule ) also ... Yes ?)

If that is so ..... then I reckon we should be REMOVING some of the 10Kgs of lead shot I have placed in the tailcone area ( to balance the "light weight" IO-320 with a NOT shortened firewall) ... Yes ???

2) The RANGE of C of G - (did it get bigger / smaller - or stay the same & move forward overall or aft overall)

3) Any salient points to keep an eye out for ?!?

AS always - your thoughts and opinions are gratefully received !

Biggus
541R

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Hello Dave & Francine,
Rick's is correct. There is a HUGE difference in performance. As for the scenic flight amongst the trees, well I did not collect any leaves or branches and the look on Biggus' face as I got an ag rating was maybe worth it!!!!! but I won't do it again. But the beloved "Traumahawk" has flown me half way around Australia and I have seen some beautiful country. I am sure my Elite will prove to be a far better platform for safely flying when I have finished building. The "Traumahawk" I now keep at RAAF Base Richmond, near my factory, so I have the luxury of 6000' of runway, air traffic controllers and get to mix and match with Hercules(C130s), F18s and F111s.

Kind regards,
Greg. G. Elite 724.



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