Aircraft Moments of Inertia Analysis Report 1

[Kristina Sornikova]

Dear All,

I looking for something guidance document on preparing a mass moments of inertia analysis report, that compares what changed between two different aircraft based on mass changes happened between them. Any tips or links please?

Thank you much...

 

[rb1957]

it's just "simple" data isn't it ?

you may get into trouble if you're changing payload and installed equipment, if you're trying to compare.

if commercial you need to consider partial payloads and people moving around the cabin, some call this the "potato" diagram.

You will need to be clear about what is accounted for where (under which heading) ...
Basic empty weight is a very basic airplane, often without an interior
Minimum flight weight has the minimum (duh!) added, like flight crew and unusable fuel and oil.
Operational empty weight would add the interior (including seats) and more crew and fuel reserves.
Max Zero Fuel weight (with is a type restriction) adds so much payload
Max take-off weight adds fuel

You need these weight distributions before you can calc mass moments.

You're modifying an existing plane ? you should be able to get the mass distributions for the unmodified plane and then calc the mass moment, and then your modified plane's masses and then mass moments.

Some more clues as to what you're doing (and why) would help.

another day in paradise, or is paradise one day closer ?

 

[Kristina Sornikova]

Thank you rb1957 Sir, but the mass moments are from the aircraft global CG?

Basically looking to compare before and after moments of a helicopter, and then somehow use the difference information to find effects on life limited parts.

 

[WKTaylor]

Society of Allied Weight Engineers [SAWE] may have useful information on this subject...

SAWE Introduction to Aircraft Weight Engineering

https://www.sawe.org/technical/publications/aircrafttextbook

SAWE RP-6, 1999: Standard Coordinate Systems for Reporting the Mass Properties of Flight Vehicles

https://www.sawe.org/technical/rp/sawe_rp-6_1999

SAWE RP-7, 2004: Mass Properties Management and Control for Military Aircraft

https://www.sawe.org/technical/rp/sawe_rp-7_2004

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[Sparweb]

Some data specific to a rotorcraft (Bell 412 / UH-1Y) can be found in this paper:

http://pubs.casi.ca/doi/pdf/10.5589/q02-021

(I only ever had the paper copy.)

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

 

[rb1957]

"the mass moments are from the aircraft global CG" ...

yes, at the end of the day you want the mass moment about the CG, but to get there you sum masses and their moments about a datum point to determine the CG location. just like calculating the centroid of a section (1st and 2nd moment of area).

another day in paradise, or is paradise one day closer ?

 

[WKTaylor]

Also, may be useful...

SAWE-P-3020 MEASURING MASS PROPERTIES OF AIRCRAFT CONTROL SURFACES

https://www.space-electronics.com/contentAssets/Literature/Control_Surfaces.pdf

ASD-TR-79-5004 Inertia Calculation Procedure for Preliminary Design

http://www.dtic.mil/dtic/tr/fulltext/u2/a072679.pdf

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[Kristina Sornikova]

Thanks all for useful responses, this link seems to have useful info.

http://www.dtic.mil/dtic/tr/fulltext/u2/a072679.pdf