VansAirForceForums  
Home > VansAirForceForums

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

- Today's Posts | Insert Pics

  #1  
Old 12-31-2018, 08:39 PM
Peter Grylls Peter Grylls is offline
 
Join Date: Oct 2018
Location: Eaglehawk, Australia
Posts: 10
Default Tail heavy.

Hi guys, happy new year.
I have recently purchased a very well built but rather "rotund" Rv4. It is a rather "vanilla", wooden prop, 150hp basic aircraft. After doing the w & b it has come in at a rather "portly" 1019 lbs. This seems pretty heavy for a pretty basic aircraft but I can't really figure where all the weight is.
My biggest concern is that it is carrying about 66lbs on the tailwheel which is very limiting as to rear passenger weight.
My question is what is a relatively normal weight on the rear wheel. I am aware that it will vary quite a bit from plane to plane, but is there a ballpark figure?
I have inspected the rear end for ballast etc. but apart from a strobe lamp everything is pretty basic. The aircraft has a pretty nice paint job, but wouldn't that add weight proportionally?
Thanks for any help you can offer.
Reply With Quote
  #2  
Old 12-31-2018, 08:59 PM
Christopher Murphy Christopher Murphy is offline
 
Join Date: Feb 2007
Location: colorado
Posts: 805
Default My RV4 numbers

Ew 975
Tailwheel 60lbs

Very light prop
Cm
__________________
RV-4 "Mr. Twister"
Pitts S1S "Mexican Red" sold and missed
Mr. Twister Airshows
Rocky Mountain Renegades
the mission... have fun.
Reply With Quote
  #3  
Old 12-31-2018, 09:09 PM
Kyle Boatright Kyle Boatright is offline
 
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 3,506
Default

Quote:
Originally Posted by Peter Grylls View Post
The aircraft has a pretty nice paint job, but wouldn't that add weight proportionally?
This doesn't count as help (as in help correcting the issue), but think about where the CG is on the airplane. Let's say it is roughly at the main wing spar. Now, consider the location of the majority of the airplane's surface area in comparison to the main spar. 2/3 of the wing is aft of the main spar, 2/3 of the fuselage is aft of the main spar, and all of the empennage is aft (far aft) of the main spar.

Where I'm going is that paint's weight is disproportionately located aft of the airplane's CG, so a heavy paint job will probably result in an aft CG.
__________________
Kyle Boatright
Atlanta, GA
2001 RV-6 N46KB
2019(?) RV-10
Reply With Quote
  #4  
Old 12-31-2018, 09:42 PM
SJordan SJordan is offline
 
Join Date: Sep 2016
Location: Scottsdale, AZ
Posts: 181
Default

Ok I have to ask. That 66lb number is with the tail up in the air right? Not in the three point attitude?
__________________
Shawn Jordan
KDVT
RV4. N11XZ
2018 dues paid.
Reply With Quote
  #5  
Old 12-31-2018, 10:50 PM
Peter Grylls Peter Grylls is offline
 
Join Date: Oct 2018
Location: Eaglehawk, Australia
Posts: 10
Default

Quote:
Originally Posted by SJordan View Post
Ok I have to ask. That 66lb number is with the tail up in the air right? Not in the three point attitude?
The figure was measured in flight position.
Reply With Quote
  #6  
Old 12-31-2018, 10:52 PM
Peter Grylls Peter Grylls is offline
 
Join Date: Oct 2018
Location: Eaglehawk, Australia
Posts: 10
Default

Quote:
Originally Posted by Kyle Boatright View Post
This doesn't count as help (as in help correcting the issue), but think about where the CG is on the airplane. Let's say it is roughly at the main wing spar. Now, consider the location of the majority of the airplane's surface area in comparison to the main spar. 2/3 of the wing is aft of the main spar, 2/3 of the fuselage is aft of the main spar, and all of the empennage is aft (far aft) of the main spar.

Where I'm going is that paint's weight is disproportionately located aft of the airplane's CG, so a heavy paint job will probably result in an aft CG.
Thanks Kyle, that makes sense to me.
Reply With Quote
  #7  
Old 01-01-2019, 09:11 AM
Sky Designs's Avatar
Sky Designs Sky Designs is offline
 
Join Date: Dec 2018
Location: Anacortes, Washington
Posts: 4
Default Add lightness to the tail

G’day Peter, you can add weight up front or you can remove weight from the back.

A quick and relatively easy way to remove one pound from the back of your bird is to replace your steel tailwheel spring with a Sky Designs titanium tailwheel spring. Go to: https://www.skydesigns.aero/titanium-tailspring

Given that the only item further aft than the tailwheel spring is the tailwheel itself, it is the second-most effective way to move your CG forward.

BTW: You’ll want to keep your old steel tailspring as it can be used for self-defense in case of a zombie apocalypse. 😉
__________________
Ken Krueger - Aircraft Designer
Sky Designs Engineering
skydesigns.aero
Reply With Quote
  #8  
Old 01-01-2019, 01:03 PM
rv7charlie rv7charlie is online now
 
Join Date: May 2006
Location: Pocahontas MS
Posts: 3,448
Default

My 1st (purchased) -4 weighed 930 lbs. The one I'm currently flying (also purchased) weighs 910 lbs. 1019 lbs for a wood prop 320 is pretty bad, if it's empty weight (was there fuel in the tanks?). With full fuel, there's not room for a normal sized pilot & still be below acro gross weight.

You didn't mention installed equipment or interior (insulation, carpet, seat cushion material, etc).

Charlie
Reply With Quote
  #9  
Old 01-01-2019, 03:38 PM
smokyray's Avatar
smokyray smokyray is offline
 
Join Date: Jan 2005
Location: TX32
Posts: 1,777
Default Weight a minute...

Quote:
Originally Posted by Peter Grylls View Post
Hi guys, happy new year.
My question is what is a relatively normal weight on the rear wheel. I am aware that it will vary quite a bit from plane to plane, but is there a ballpark figure?
Thanks for any help you can offer.
G'Day Pete,
My Sterba Wood Prop equipped RV4 weighed 925lbs empty the day of it's test flight. For it and many others I have inspected over the years I use 50lbs in level flight attitude on the tail-wheel as a good ballpark number for CG ballpark calculations.
There are many ways to help shift the CG on a wood propped Four and reduce weight. Use these suggestions to search for and evaluate your own 4.

1. Odyssey Battery (vice certified aircraft battery) mounted as far forward as possible. I mounted mine on the "shelf" forward of the firewall. R&R of your 26lb aircraft battery to an Odyssey or Lithium will save up to 15 lbs. If it's mounted in the baggage compartment, that will weigh heavily on the TW.
2. Radios, panel, unnecessary items. If you have old radios, power supplies, instruments, round dials, they all add up. Make a list of the heavier ones and look at digital (MGL) or even removal of the unneeded ones.
3. Insulation. Cockpit soundproofing, insulation, thick foam seat cushions add weight. My Four had minimum frills inside and NASA foam seats with light upholstery.
4. Heavy weight Starter/Alt and Mags. A full size Prestolite Starter and certified aircraft alternator weigh nearly twice that of a lightweight version. Bendix Mags weigh twice that of a P-Mag or most Electronic ignitions. There are many vendors out there and you might be able to sell your old ones online.
5. Prop extension. If you remove the heavier starter you can offset the less nose weight by going with a steel prop extension from Saber Mfg.

These are just a few "tricks" you can apply, email me anytime offline and we can start working the issues.
Fair Dinkum...

Smokey
smokyray@rocketmail.com

Last edited by smokyray : 01-01-2019 at 03:43 PM.
Reply With Quote
  #10  
Old 01-01-2019, 08:02 PM
FinnFlyer FinnFlyer is offline
 
Join Date: Aug 2018
Location: Bell, FL
Posts: 93
Default

Quote:
Originally Posted by Sky Designs View Post
G’day Peter, you can add weight up front or you can remove weight from the back.

A quick and relatively easy way to remove one pound from the back of your bird is to replace your steel tailwheel spring with a Sky Designs titanium tailwheel spring. Go to: https://www.skydesigns.aero/titanium-tailspring

Given that the only item further aft than the tailwheel spring is the tailwheel itself, it is the second-most effective way to move your CG forward.

BTW: You’ll want to keep your old steel tailspring as it can be used for self-defense in case of a zombie apocalypse. 😉
You guys are really from the future? Copyright 2023

Finn
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 04:02 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.