This paper discusses the plausibility of the thruster in the Iron Man suit being used as weapons to push a human back. It was determined that the shock-wave produced by the change in temperature due to the thrusters would produce a force of $183$ kN on a person it was shot at, this would cause the person to accelerate at $2614$ ms$^{-2}$ killing the person

Cobley, Dillon

Fenlon-Smith, D

Jupp, M

Yeomans, K

English

University of Leicester Open Journals

Journal of Physics Special TopicsAn undergraduate physics journalP4 6 Wind sweptD.Cobley, M.Jupp, K.Yeomans, D.Fenlon-SmithDepartment of Physics and Astronomy, University of Leicester, Leicester, LE1 7RHDecember 6, 2016AbstractThis paper discusses the plausibility of the thrusters in the Iron Man suit being used as weapons to pusha human back. It was determined that the shock-wave produced by the change in temperature due tothe thrusters would produce a force of 183 kN on a person it was shot at, this would cause the person toaccelerate at 2614 ms−2, likely killing the person.IntroductionIn the Marvel extended universe the characterTony Stark (the ‘Iron Man’) uses a powered ex-oskeleton to fight crime. In recent incarnationsof the character the Iron Man suit provides thewearer with super strength, the ability to fly andis filled with an assortment of weapons. In thispaper we will be focusing on small energy-basedthrusters that sit in the palms of the hands andsoles of the feet. We will use the energy requiredto produce small bursts of ‘flight’ (more akinto jumps) to deduce whether or not they couldactually propel a person a short distance awaybackwards if ‘fired’ at them.To determine whether the Iron Man suit is capa-ble of such a ‘pushback’, the change in temper-ature of the air in front of the thrusters needsto be calculated. For this paper, the initial forceof lift-off is assumed to be provided by rapidlyheating the air under the suit’s thrusters, this‘∆T ’ is found by equating the weight of the suitto the force provided by an near-instantaneousincrease in pressure below caused by the tem-perature change.From visual inspection the thrusters are as-sumed to be circles of radius r = 0.03 m and thesuit taken as roughly 0.01 m thick, Tony Starkis assumed to weigh 70 kg with a surface area of1.9 m2 [1]. In the films the Iron Man suit is saidto be made from a ‘titanium-gold alloy’, this pa-per will use β−Ti3Au due to it being four timesstronger than pure titanium [2]. From Fig.1 ofthe referenced article, this compound has a den-sity of approximately 800 kgm−3 (from Fig.1 ofthe article). Using the density, surface area andthickness of the suit, we find it to have a mass of15.2 kg, giving an overall mass to be lifted, m,of 85.2 kg.P1 =nRT1V(1)P2 =mgA=nRT2V(2)n =ρairVMmol(3)The symbols in the ideal gas equations abovehave their usual meanings, with P1 and P2 beinginitial and final pressures, m is the mass of thesuit, A is the area over which the pressure changeacts, n is the number of moles of air, with ρairbeing the density of air at T1 of 1.225 kgm−3, andMmol the molar mass of air, 0.0290 kgmol−1.Rearranging equations (1),(2) and (3) gives anequation for the change in temperature requiredto change pressure by the requisite amount:∆T = T2 − T1 = mgVAnR− P1VnR(4)Using the above figures gives a ∆T of 258 K.C =(γP1ρ)0.5(5)P2 =2ρv2γ + 1(6)To calculate the push-back received by a personat range, we model the shock-wave caused bythe rapid increase in air temperature around thethruster, using equations (5) and (6)[3], we usethe sound speed C in the expanded gas (assum-ing instantaneous expansion) as the value for vin the second equation, using the density of airat T2 of 0.4 kgm−3 for P1 and a γ of 5/3, thisgives a sound speed of 948 ms−1.Using this velocity, the pressure of the shock-wave becomes 270 kPa. Over the full frontal areaof a human of 0.68 m2 [4], this amounts to aforce of 183 kN. If this force was applied to aperson within one meter, the radial fall off of theshock-wave would be negligible; because of thisthe force that the person would experience dueto the shock-wave would easily knock a personback, with an average acceleration , given by F =ma, of 2614 ms−2. This would likely kill anyonethat it would hit, as the human body cannotsurvive an acceleration of 266 g.ConclusionThe Marvel character Tony Stark’s Iron Mansuits’ energy-based thrusters use the tempera-ture change of the air under the thrusters to pro-vide an upward force to induce flight, this tem-perature change was found to be 258 K. Thesethrusters can also be used as weapons by pro-ducing a shock-wave, it has been calculated thata person hit by this would feel a force of 183 kN,this amount of force would result in an acceler-ation of 2614 ms−2, likely resulting in the deathof anyone hit by it.References[1] http://www.medicinenet.com/script/main/art.asp?articlekey=39851 accessed18/11/16[2] E.Svanidze at al, High hardness in the bio-compatible intermetallic compound β−Ti3Au(2016)[3] https://blackboard.le.ac.uk/bbcswebdav/pid-1415611-dt-content-rid-3655490_2/courses/PA4480/fluids2016.pdf ac-cessed 23/11/16[4] http://onlinelibrary.wiley.com/doi/10.1256/wea.29.02/pdf accessed 23/11/16[5] http://www.engineeringtoolbox.com/air-density-specific-weight-d_600.html accessed 18/11/16

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P4_6 Wind swept

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