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ACRO E-mail Archive Thread: [Acro] RE: S1S aux fuel tank capacity?

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ACRO E-mail Archive Thread: [Acro] RE: S1S aux fuel tank capacity?


Thread: [Acro] RE: S1S aux fuel tank capacity?

Message: [Acro] RE: S1S aux fuel tank capacity?

Follow-Up To: ACRO Email list (for List Members only)

From: "Seppanen, Kari J" <kari.j.seppanen at>

Date: Thu, 19 Sep 2002 01:52:08 UTC


The number we use for fuel expansion due to temperature is 0.0063 lb/gal/deg
C, so -40 to +40 deg C would give you about a half pound change as noted.
That's for Jet A but Avgas will be similar. We also get about a 3 pct range
in density depending on the refinery and batch. Still very much in the nits
for the original question. ;-)
Kari J. Seppanen

Flight Test Engineering Analysis 

Aerodynamic Performance Group

kari.j.seppanen at

-----Original Message-----
From: Fly [mailto:fly at]
Sent: Tuesday, September 17, 2002 6:10 PM
To: Seppanen, Kari J; petera at; acro at
Subject: [Acro] RE: S1S aux fuel tank capacity?

It is nitpicky for an aux 5 or main 19 gals, but something else like a twin
or jet with 200-400 gals. it makes a difference!
 When weighing something like that,  I measure by hydrometer.  Hot summer
months, its lighter than average so if you want the lightest legal weight,
use the average book figures.
Cold weather, always use the the actual weight.   
For jet fuel, something like a 1/2 pound difference per gallon summer to
Also..........Peter, thanks for your reply.  I missed your message at first
so couldn't answer directly..
Kent Felkins

----- Original Message ----- 
From: Seppanen, Kari J <mailto:kari.j.seppanen at>  
To: 'petera at' <mailto:'petera at'>  ;
'Fly' <mailto:fly at>  ; acro at <mailto:acro at>  
Sent: Monday, September 16, 2002 10:13 PM
Subject: [Acro] RE: S1S aux fuel tank capacity?

According to Chevron, Avgas is typically 0.715 Sg or 5.97 lb/gal (US) at 60
deg F if you want to get picky....
-----Original Message-----
From: Peter Ashwood-Smith [mailto:petera at]
Sent: Friday, September 13, 2002 7:56 PM
To: 'Fly'; acro at <mailto:acro at> 
Subject: [Acro] RE: S1S aux fuel tank capacity?

The stock smoke tank in the upper wing is 5 gallons. I'm looking at the
original 337 for my S-1T and it has all the details.

As for the weight of the smoke oil. You can get that from its specific
gravity. The canopus-13 data sheet from Texaco shows it's specific gravity
as .85, gasoline is shown on another materials site as having a specific
gravity of about .75. Therefore one can expect smoke oil to be .85/.75  as
heavy as gasoline per unit volume.  So, do you normal gasoline weight
calculations and then multiply by 1.13 and you should be in the ballpark.

After all this work you will find out you were over gross before you even
put a drop of water/gas/smoke oil or anything else in that top tank ;)


	BM__MailData-----Original Message----- 
From:   Fly [SMTP:fly at] 
Sent:   Friday, September 13, 2002 1:44 PM 
To:     acro at 
Subject:        [Acro] S1S aux fuel tank capacity? 

	Hi Folks, 

	I just weighed a plans-built Pitts S1S that was built in 1979.   It
has the 
aux fuel tank in the upper wing center section but it is being used as a 
smoke oil tank.     There is no documentation in the records for this tank. 
The temporary owners don't know.... plus despite my request, they filled the

tank instead of draining it. 

	It appears to have stock wings. 
Any guesses on the capacity of this tank? 
Also, what does smoke oil weigh? 

	In the papers, I saw a 1979 sales brochure for an "Ultimate poly
tank" that 
had a 4 gal capacity. 
It show a center drain.  This S1S had the lines coming down the left forward

center strrt. 

	Thanks for any help, 

	Kent Felkins 

	  fly at 


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