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  #11  
Old 02-21-2021, 08:20 AM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
 
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Default

Fair enough. But if you plug the values into a calculator as read (left to right) you get the number - which is what the OP asked.

Just trying to show the sequence within the limits of typing on a phone.
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  #12  
Old 02-21-2021, 09:31 PM
dmattmul dmattmul is offline
 
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Default Fuel Arm final answer

=82.58-((B15-5)*(1.22/45))

I'm not going to defend, elaborate or debate but you can judge for yourself. B15 is the input in gals to quantify the Fuel Arm in inches. Yes other assumptions as to where the baggage is placed also adds to the error. I just like to define as close as possible the inputs if possible. The weight (In lbs.) of the fuel still needs to be used to calculate the moment.
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RV-14A QB building, Lycoming 390 Thunderbolt arrived July 2019, Garmin avionics, Vertical Power, EFII-32 Ignition and Fuel, Whirlwind 300-72, Parts became a real airplane 8/15/2020.
Started RV-10 Nov 2020. Empennage arrived and now waiting (And waiting) for QB kits. Garmin avionics, Vertical Power, EFII-32 Ignition and Fuel, Whirlwind 3 blade, real airplane hopefully 2022.
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  #13  
Old 02-26-2021, 10:58 AM
sloengineer sloengineer is offline
 
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I made a spreadsheet that plots the W&B. This is not a real aircraft empty weight, I just used the Van's supplied demonstrator weights until ours is finished. Helps to see when you're in the aerobatic category or not. Also calculates Va at specific W&B. Here's a screenshot....
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  #14  
Old 02-27-2021, 07:53 AM
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jeffw@sc47 jeffw@sc47 is offline
 
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Default calc Va

Quote:
Originally Posted by sloengineer View Post
. . . Also calculates Va at specific W&B. Here's a screenshot....
What is the formula for calculating the Va?
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1946 Bellanca Cruisair 14-13-2 (74 YRS OLD 8/1/20)
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  #15  
Old 02-28-2021, 12:23 PM
sloengineer sloengineer is offline
 
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Quote:
Originally Posted by jeffw@sc47 View Post
What is the formula for calculating the Va?
Here's a link to the Van's website wherein they discuss the speed limitations of the RV-14 series.

https://www.vansaircraft.com/wp-cont...4_V_speeds.pdf

Short answer: Va=(stall speed)*squareroot(load factor) For example Va=62kt*sqrt(4.4g) or 130kt

Long answer: First you need to know if you're in the aerobatic load category (6g) or the utility category (4.4g). Then you need to know your stall. My spreadsheet extrapolates the stall speed based on the weight, then the load factor based on both weight and CG. Then Va as described above.

An interesting note about the load factor: depending on weight and fuel burn during the flight, you could start in the utility category, pass through aerobatic, then end up back in utility at landing. Thus my personal minimum is to calculate Va at my zero fuel weight and utility load factor. That's not a recommendation, just my personal preference.
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Last edited by sloengineer : 03-01-2021 at 09:11 AM. Reason: Added Van's web link.
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