Actually, many mechanics weigh airplanes with full fuel, then subtract the weight of the useable fuel.

If you weigh without any fuel, you have to add the weight of the unusable fuel after weighing, or you'll come up with an artificially low figure.

MTV

1813

Good luck Kev! That spinner looks awesome too BTW.

1852

1812 #

1875

1905.

Can't wait for the prop comparison results; thanks for the thread.

1900 on the money.

Have fun on that 1st flight!

mtv wrote:Actually, many mechanics weigh airplanes with full fuel, then subtract the weight of the useable fuel.

If you weigh without any fuel, you have to add the weight of the unusable fuel after weighing, or you'll come up with an artificially low figure.

MTV

MTV-
Not really certain I understand that... Why not just add the 6.2lbs per gallon for the 5 that are or add the 5 gallons to get it accurate?

This is an interesting read...

DATA PERTINENT TO ALL MODELS (cont’d)
The basic required equipment as prescribed in the applicable airworthiness regulations (see Certification Basis) must be installed in the aircraft for certification. This equipment must include a current Airplane Flight Manual effective S/N 18052490, 18053001 and on. In addition, the following item of equipment is required.
1. Stall Warning Indicator, Cessna Dwg. 0511062 through S/N 18051823. 2. Stall Warning Indicator, Cessna Dwg. 0700185 effective S/N 18051824 and on.
The equipment portion of Aircraft Specification 5A6, Revision 34, or Cessna Publication TS2000-12 should be used for equipment references on all aircraft prior to the Model 180G. Refer to the applicable Equipment List for the Model 180G and subsequent models.
Current weight and balance report together with list of equipment included in certificated empty weight and loading instructions when necessary must be provided for each aircraft at the time of original certification. The certificated empty weight and corresponding C.G. location must include unusable fuel of 30 lb. at (+46) on Models 180, 180E, 180F, 180G, 180H, 180J, and 180K through S/N 18053000, and 60 lbs. at (+48) on Models 180A, 180B, 180C and 180D, and undrainable oil of 0.0 lbs. at -15.0 through S/N 1805260; full oil of 22.0 lbs. at -15.0 S/N 18052621 and on.
The certificated empty weight and corresponding center of gravity locations must include unusable fuel of 24 lb. at +48 (S/N 18052490, 18053001 and on).

Here is the link to the above: Interesting that early models say 24lbs unusable and later mods say 30lbs
http://www.john2031.com/photos/cessna/180/5A6.pdf

This is real interesting and explains what MTV is saying: http://www.skywagons.com/modelchgsweb.html
Fuel Tanks

The fuel system is a simple gravity-flow type with wing mounted fuel cells. Standard gas capacity is 60 gallons total for the 1953-56 models and the standard capacity is 65 gallons for the 1957-64 models. In 1961, large optional tanks totaling 84 gallons were offered for the first time on the 185, in 1962 they became available on the 180 also. The 1953-61 models have a single outlet in each tank. Beginning with the 1962 models, two fuel pickups are used in each fuel cell, fore and aft, rather than one. Addition of this second fuel outlet in each wing cell has the effect of giving less unusable fuel in some of the adverse attitudes of flight. The fuel outlets are coupled through a four-position selector valve and both tanks can be used at once or each separately. The fourth position is off.


Due to the high angle of climb and descent possible and being of the gravity feed type, the usable fuel of these tanks has to be rated as to all attitudes of flight. This causes confusion as some models are listed as carrying up to 5 gallons of fuel in each tank as unusable. This is true only in very unusual attitudes. In level or normal flight, the 180 will use all but 1- 1 1/2 gallons of fuel from each cell. Most of this could actually be used in an emergency by flying with one wing high and then the other wing high to allow this fuel to run to the pickup area.


In 1957, the gross weight of the 180 aircraft was increased by 100 lbs. and the fuel capacity increased from the original 60 gallons (30 per wing) to 65 gallons total. Due to the new all attitude requirement, the usable fuel was rated at 55 gallons. Since unusable fuel is part of the aircraft’s empty weight, it may be noted that the empty weight appears to have increased by about 50 lbs. and the useful load gain only 50 lbs. in the 1957 model - when actually the useful load is really increased about 100 lbs. except in unusual flight attitudes.
Regardless, she is getting weighed this am and I will let my mechanic choose what we are doing. This will definitely be a discussion prior.

Thanks for your input!

AKT

AKT, Although your blog post claims the plane weighs 1844 pounds empty.... based upon the weight of my bird... plus and minus your mods... I'm going with 1755lbs. Good luck on the weigh-in.

1825

1844

1865

I'm going with 1789lb

1884

1832

1788 Haha

mtv wrote:Actually, many mechanics weigh airplanes with full fuel, then subtract the weight of the useable fuel.

This is what I did when weighing my old 170.

aktahoe1 wrote:In level or normal flight, the 180 will use all but 1- 1 1/2 gallons of fuel from each cell. Most of this could actually be used in an emergency by flying with one wing high and then the other wing high to allow this fuel to run to the pickup area.

Has anyone ever done this? Held a wing high so as to use the unusable?

Sorry, I'm joining the heavy crowd: 1903#'s. She looks beautiful!! Can't wait to see the first flight vid.

CW

1814



Gump