VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #1  
Old 07-27-2019, 04:18 PM
N804RV's Avatar
N804RV N804RV is offline
 
Join Date: May 2013
Location: Mount Vernon, Wa
Posts: 493
Default Weight and Balance again

I'm looking for someone that built a -8 with a parallel valve O/IO-360 and fixed pitch prop that would be willing to share their W&B data with me.

I did a search of the site and didn't really see what I was looking for.

My questions are:

1) how much the SkyDesigns Aluminum landing gear will affect CG.

2) about where CG will fall with LiPo4 vs AGM battery and/or FWD/Aft location


My goal for the aircraft is to keep it light, and keep the CG optimum.
__________________
Ken W.
Mount Vernon, WA
2019 VAF Supporter
Reply With Quote
  #2  
Old 07-27-2019, 05:40 PM
Robin8er Robin8er is offline
 
Join Date: Sep 2015
Location: Socal
Posts: 322
Default

I have a wood prop and standard battery up front. My plane is tail heavy.

If your plane is some how nose heavy, it's easy to fix with ballast in the baggage compartment. If its tail heavy there isn't much you can do about it.

I vote keep the weight up front as much as you can if you plan on carrying passengers and baggage.

If you paint the plane it will tend to move the cg rearward as most of the paint goes behind the cg.
__________________
RV-8 N695RA flying
Working on an RV-4

Born to fly, forced to work
Reply With Quote
  #3  
Old 07-27-2019, 06:43 PM
springer springer is offline
 
Join Date: May 2012
Location: AZ/MN
Posts: 340
Default

Quote:
Originally Posted by Robin8er View Post
I have a wood prop and standard battery up front. My plane is tail heavy.

If your plane is some how nose heavy, it's easy to fix with ballast in the baggage compartment. If its tail heavy there isn't much you can do about it.

I vote keep the weight up front as much as you can if you plan on carrying passengers and baggage.

If you paint the plane it will tend to move the cg rearward as most of the paint goes behind the cg.
I don't understand how your -8 is tail heavy in the configuration as you describe. Mine is built light but with a metal Sensenich FP prop and Odessey battery on the firewall and I think it is too nose heavy solo even with 25# of ballast in the aft baggage compartment. The heavy stick pressure is not where I would like it especially when compared to my RV-4 which I thought was perfect. I would think yours with the wood prop would be near perfect as well.
__________________
Jim
RV-4 '88-'09 Built & Sold
RV-8 Purchased
Reply With Quote
  #4  
Old 07-27-2019, 06:52 PM
N804RV's Avatar
N804RV N804RV is offline
 
Join Date: May 2013
Location: Mount Vernon, Wa
Posts: 493
Default

Quote:
Originally Posted by Robin8er View Post
I have a wood prop and standard battery up front. My plane is tail heavy.

If your plane is some how nose heavy, it's easy to fix with ballast in the baggage compartment. If its tail heavy there isn't much you can do about it.

I vote keep the weight up front as much as you can if you plan on carrying passengers and baggage.

If you paint the plane it will tend to move the cg rearward as most of the paint goes behind the cg.
Quote:
Originally Posted by springer View Post
I don't understand how your -8 is tail heavy in the configuration as you describe. Mine is built light but with a metal Sensenich FP prop and Odessey battery on the firewall and I think it is too nose heavy solo even with 25# of ballast in the aft baggage compartment. The heavy stick pressure is not where I would like it especially when compared to my RV-4 which I thought was perfect. I would think yours with the wood prop would be near perfect as well.

Thank you!

Food for thought. And, a good argument for not painting till the initial W&B is sorted out.
__________________
Ken W.
Mount Vernon, WA
2019 VAF Supporter
Reply With Quote
  #5  
Old 07-31-2019, 10:22 PM
Lyle RV8 Lyle RV8 is offline
 
Join Date: Apr 2014
Location: Davis, Ca
Posts: 17
Default

I built my RV8 light so thought this might be helpful.

Build summary - O360, 3 blade Catto prop, PC680 mounted on the firewall, Grove airfoil gear, VFR avionics (GRT Sport EX, tablet for nav, Sandia transponder, single Garmin radio, Uavionix ADSB in/out), no autopilot.

Empty weight: 1,024 lbs (includes all paint, fairings, even fire extinguisher)
CG: 78.04"

I was concerned about aft CG as well and was careful not to add weight behind the wings. Minimal avionics aft of the baggage area (Uavionix ADSB, ELT) and no exterior paint aft of the wing. I hate polishing but that is the price to pay.

I am quite happy with the CG and performance.
__________________
Lyle McCarty

Slow build RV8
First flight March 2018, 180 hours and counting

Rans S-18 built and flying, 1,100 flight hours
Reply With Quote
  #6  
Old 07-31-2019, 10:46 PM
N804RV's Avatar
N804RV N804RV is offline
 
Join Date: May 2013
Location: Mount Vernon, Wa
Posts: 493
Default

Quote:
Originally Posted by Lyle RV8 View Post
I built my RV8 light so thought this might be helpful.

Build summary - O360, 3 blade Catto prop, PC680 mounted on the firewall, Grove airfoil gear, VFR avionics (GRT Sport EX, tablet for nav, Sandia transponder, single Garmin radio, Uavionix ADSB in/out), no autopilot.

Empty weight: 1,024 lbs (includes all paint, fairings, even fire extinguisher)
CG: 78.04"

I was concerned about aft CG as well and was careful not to add weight behind the wings. Minimal avionics aft of the baggage area (Uavionix ADSB, ELT) and no exterior paint aft of the wing. I hate polishing but that is the price to pay.

I am quite happy with the CG and performance.

Sounds very cool! Can I see pictures?
__________________
Ken W.
Mount Vernon, WA
2019 VAF Supporter
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 12:03 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.