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  #41  
Old 03-14-2017, 09:46 AM
Chattin35 Chattin35 is offline
 
Join Date: Jul 2014
Location: Boise, ID
Posts: 185
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Quote:
Originally Posted by roadrunner20 View Post
IO360, 2005 catto 3 blade

Here's my morphed 7A to 7 data
7A CG = 81.88, empty weight 1081
7 CG = 81.11, empty weight 1065

Since I will be installing the landoll ring, I was looking at the data today, my cg moved forward on the conversion.

The 12# ring will help, but I will also keep my lead scuba bean bags on my inside firewall. I created a dam to hole them forward.
Very interesting. Thanks Dan.

I'm about a week away from weighing mine -- taildragger, IO-360-M1B, Hartzell BA, light VFR glass panel, built to plans. Should be interesting. I'll post the #'s when I have them.
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  #42  
Old 03-14-2017, 11:18 AM
rzbill's Avatar
rzbill rzbill is offline
 
Join Date: Nov 2005
Location: Asheville, NC
Posts: 2,399
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Quote:
Originally Posted by roadrunner20 View Post
IO360, 2005 catto 3 blade

Here's my morphed 7A to 7 data
7A CG = 81.88, empty weight 1081
7 CG = 81.11, empty weight 1065

Since I will be installing the landoll ring, I was looking at the data today, my cg moved forward on the conversion.

The 12# ring will help, but I will also keep my lead scuba bean bags on my inside firewall. I created a dam to hole them forward.
Interesting indeed. The CG change data is counterintuitive to me.

On the assumption that there were not any other items relocated unrelated to the 7A to 7 change, the CG moving forward indicates that the main gear relocation has a major effect on CG position between the 7 and 7A.

The nose gear removal and tail wheel addition are both "rearward CG" moves so the main gear repositioning had to more than compensate for both of them.

I have had recent "idle" thoughts about converting to a 7. It will take a mighty big "round tuit" though.

When I was building 7A 10 years ago, I had seen posts about rear CG tendency but I did not realize it was the taildragger being described. I pushed everything forward during construction and have an empty CG of 78.7" which is quite far forward. It is essentially impossible for me to load the craft out the back of the envelope. Downside is my nosewheel weight is high although still within Vans limits in all loading scenarios.

For reference:
7A unpainted tip up
IO-360-M1B/Hartzell
IFR Glass w/ steam BU
Some fabric interior by SWMBO
Kevlar/ceramic floorboards
1109 lbs
78.7 empty CG
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Bill Pendergrass
RV-7A: Flying since April 15, 2012. 650hrs
YIO-360-M1B, mags, CS, GRT EX and WS H1s & A/P, Navworx
Unpainted, polished....kinda'
My RV Construction Page

Last edited by rzbill : 03-14-2017 at 04:29 PM.
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  #43  
Old 03-14-2017, 12:32 PM
roadrunner20's Avatar
roadrunner20 roadrunner20 is offline
 
Join Date: Feb 2005
Location: Bay Pines, FL (based @ KCLW)
Posts: 1,746
Default

Quote:
Originally Posted by rzbill View Post
Interesting indeed. The data is counterintuitive to me.

On the assumption that there were not any other items relocated unrelated to the 7A to 7 change, the CG moving forward indicates that the main gear relocation has a major effect on CG position between the 7 and 7A.

The nose gear removal and tail wheel addition are both "rearward CG" moves so the main gear repositioning had to more than compensate for both of them.

I have had recent "idle" thoughts about converting to a 7. It will take a mighty big "round tuit" though.

When I was building 7A 10 years ago, I had seen posts about rear CG tendency but I did not realize it was the taildragger being described. I pushed everything forward during construction and have an empty CG of 78.7" which is quite far forward. It is essentially impossible for me to load the craft out the back of the envelope. Downside is my nosewheel weight is high although still within Vans limits in all loading scenarios.

For reference:
7A unpainted tip up
IO-360-M1B/Hartzell
IFR Glass w/ steam BU
Some fabric interior by SWMBO
Kevlar/ceramic floorboards
1109 lbs
78.7 empty CG
I also have the forward induction, but mine is a Superior model. But notice, my catto prop weighs in at 18# moving my cg considerable aft
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Dan "RoadRunner" Landry
Morphed RV7, N20DL, PNP Pilot
1010+ hours, hit 1000 enroute to Oshkosh
2017 Donation Paid
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  #44  
Old 03-24-2017, 02:31 AM
Pin 21 Pin 21 is offline
 
Join Date: Mar 2009
Location: South Australia
Posts: 16
Default VH-UER

Fairly disappointed in the results from a loooong slow build (10 years)

RH main = 531
LH main = 530
Tailwheel = 75

C of G = 80.8"

Painted and ALL parts fitted. RV-7 Io-360 parallel valve, Whirlwind prop. Classic interior.

Last edited by Pin 21 : 03-27-2017 at 03:08 AM.
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  #45  
Old 03-24-2017, 06:17 AM
roadrunner20's Avatar
roadrunner20 roadrunner20 is offline
 
Join Date: Feb 2005
Location: Bay Pines, FL (based @ KCLW)
Posts: 1,746
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I installed the landoll ring last weekend.
It moved my cg forward from 81.11 to 80.48
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Dan "RoadRunner" Landry
Morphed RV7, N20DL, PNP Pilot
1010+ hours, hit 1000 enroute to Oshkosh
2017 Donation Paid
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  #46  
Old 03-29-2017, 09:43 PM
Chattin35 Chattin35 is offline
 
Join Date: Jul 2014
Location: Boise, ID
Posts: 185
Default N437T #'s

RV-7
Quickbuild
IO-360-M1B
Hartzell BA CS Prop
VFR glass panel (dual GRT Horizons)
Classic Aero Sportsman seats
Built light and to the plans
Weighed on certified and calibrated scales
Equipped for 1st flight (see pic below)

Left: 492
Right: 494
Tail: 57

Total: 1043

Stoked!

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  #47  
Old 06-30-2017, 10:04 AM
EinEngineer's Avatar
EinEngineer EinEngineer is offline
 
Join Date: Jun 2017
Location: Lafayette, LA
Posts: 4
Default Same problem on the -14?

Quick question from the new guy:

I'm still a ways away from starting a build, but my mission includes light aerobatics, occasionally with a friend. While I'm just under 170#, some of my compatriots are around 220#. Playing with a few of the numbers you've listed, I just don't see how it'd be possible to stay within the aerobatics 84.5" aft CG limit if my empty CG comes out to anything above 80".

Does anyone know if the -14 suffers from a similar aft CG tendency? After a quick search I didn't see any discussion in the -14 forums about a similar topic, so I figured I'd address it here before starting something new over there.

Best,
Will

Note: I'm more concerned about Aerobatics CG comparison between the two. I know both the -7 and -14 will perform well for me during cross country flight.

Last edited by EinEngineer : 06-30-2017 at 10:47 AM. Reason: Note
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