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Development and evaluation of a six degrees of freedom model of a 155 mm artillery projectile
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
2015 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Utveckling och evaluering av en sex frihetsgrads modell av en 155 mm artilleri granat (Swedish)
Abstract [en]

In this Master Thesis, the author has evaluated a six degrees of freedom model of a 155 mm artillery projectile commonly used in the Swedish Armed Forces and compared it to a modified point mass trajectory model of the same projectile. Uncertainties in the six degrees of freedom model were assumed to evaluate the precision of the model compared to the precision of the real fire data. The models were simulated using the software FLAMES, thatuses a spherical earth model, terrain data and measured atmospheric conditions. The real fire data comes from a number of fire series performed by the Swedish Armed Forces in 2001. The results showed that six degrees of freedom model was accurate in length but had an upwards 35 % error in drift when verified against a firetable. When the six degrees of freedom model was compared to a modified point mass model and real fire hits the mean distance to target was about 250 m. A plausible reason for this large mean distance is that the in data used in this thesis had to low order of accuracy. This thesis also showed a large difference in angle of attack between the models during high elevation simulations as well as when there was wind present. The results for the six degrees of freedom model with uncertainties showed that 90 % of all projectiles hit within a 50 m x 75 m ellipse, at a simulated fire distance of about 16 km.

Abstract [sv]

I detta examensarbete har författaren utvärderat en sex frihetsgrads modell av en 155 mm artillerigranat som används av den svenska Försvarsmakten och jämfört den med en modifierad punktmassa modell av samma projektil. Osäkerheter antogs i sex frihetsgradsmodellen för att utvärdera modellens precision mot verklig precision. Modellerna simulerades i programmet FLAMES, med en sfärisk jordmodell, terräng data och uppmätta atmosfäriska förhållanden. Skjutdatan som användes som jämförelse kommer från en skjutning i Boden år 2001 utfört av den svenska Försvarsmakten. Resultaten visade att sex frihetsgrads-modellen var korrekt i längd, men hade uppåt 35 % fel idrift när den verifierades mot en skjuttabell. När sex frihetsgrads-modellen jämfördes med skjutdata från en riktig skjutning var medelavståndet från riktigt nedslag till nedslag för sex frihetsgrads-modellen ca 250m. En trolig orsak till det stora medelavståndet är att indata som användes hade en noggrannhet som inte var tillräckligt hög. Detta examensarbete visade också en stor skillnad i anfallsvinkeln mellan modellerna under höga skjutvinklar samt när det fanns vind närvarande. Resultaten för sex frihetsgrads-modellen med osäkerheter visade att 90% av alla projektiler träffar inom en 50 m x 75 m ellips, vid skjutning på cirka 16 km avstånd.

Place, publisher, year, edition, pages
2015. , 40 p.
Series
TRITA-MMK, ISSN 1400-1179 ; 2015:94 MDA 523
National Category
Mechanical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-182753OAI: oai:DiVA.org:kth-182753DiVA: diva2:905698
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Examiners
Available from: 2016-03-07 Created: 2016-02-23 Last updated: 2016-03-07Bibliographically approved

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