Kufanana kwa rocket ndi delta-v

Mu 1903, Konstantin Tsiolkovsky, wophunzira wa ku Kaluga, adalemba zofanana zomwe mpaka pano zimatha kupanga ma roketi onse. Izi zikufotokoza chifukwa chake Falcon 9 ndi zokhudzana 89% propeller, chifukwa cha payload ndi okha peresenti zingapo za kulemera pa liftingoff, ndipo chifukwa chiyani roketi kugwa mbali ya iwo okha pa njira mpaka.

Nthawi zonse, rocket ndi mpikisano pakati pa liwiro mukufuna ndi maselo muyenera kunyamula kuti muyambe.

Onani

A Rocket amayenda ndi kumeta maselo m’mbuyo. Kudula mofulumira, kapena kudula zambiri za izo, ndipo inu mupite mofulumira. Pali kuswa: mafuta omwe simukuwonongabe ayeneranso kuthetsedwa ndi kufulumizitsa. Izi amachititsa kukhudzidwa logarithmic: kuti muwonjezere mlingo wofanana wa kufulumira, muyenera kuwonjezera mafuta, sikuti kuwonjezera pa izo.

Delta-v (Δv, “change in velocity”) is the currency of spaceflight. Mphamvu iliyonse imakhala ndi mtengo wake m’ma km/s:

• Kuchokera pamalo a dziko lapansi mpaka ku orbiti ya pansi: pafupifupi 9.4 km/s, kuphatikizapo kuwonongeka.
• Orbit Low mpaka geostationary orbit: pafupifupi 3.9 km / s.
• Orbit Low kuchoka padziko kuti Mars: za 3.6 km / s.

Mtengo wa mafuta ndi ndalama zomwe zimaperekedwa kuti zithandizire kugulitsa mafuta, mafuta a gasi ndi mafuta ena.

Kumvetsa

Δv = I_sp · g₀ · ln(m₀ / m_f)

• I_sp: kupweteka kokha, njira yowerengera chitetezo cha injini m’masekondi (mtunda wotulutsa wogawidwa ndi g₀).
• g₀ = 9.80665 m/s², standard gravity.
• m₀: maselo pamapeto pake; m_f: maselo pamapeto pake.

Mofananamo ndi gawo lachiwiri la rocket (Isp 348 s): lokwanira, limakhala ndi masentimita 112 kuphatikizapo 15-masentimita payload; lopanda mafuta oyendetsa, pafupifupi masentimita 19. Δv = 348 × 9.81 × ln(112 / 19) ≈ 6.0 km/s. M’malo mwake, gawo loyamba limawonjezera zina.

Mtundu wa 10 ndi Isp 350 s amapatsa 7.9 km / s, sichoncho chokwanira kuti chikhale m’mimba mwake pamene kuwonongeka kwachidziwitso kumawerengedwa, ndipo kapangidwe kake ndi kokha 10% ya zoposa zonse ndizozizira kwambiri. M’madera ena, mapiri amadzimadzi amagwiritsa ntchito njira ziwiri kapena zambiri.

Woyang’anira

Kusintha kwa magazi kumayambitsa kuwonjezeka kwa maselo a m’mawere. Kwa katundu awiri-stage,

Δv_total = I₁ g₀ ln(m₁₁/m_f₁) + I₂ g₀ ln(m₁₂/m_f₂)

pamene mlingo wachiwiri woyamba umatenga chilichonse chomwe chidatulutsidwa panthawi yoyamba. Kusintha kwa mfundo za m’madera (kwa Isp yofanana, pafupifupi Δv yofanana pamalo) ndi vuto lachikhalidwe: payload fraction imagwa mofulumira kwambiri ndi Δv yofunikira, chifukwa chake kuchepetsa Δv kuti ipite ku orbit ndi mamiliyoni angapo a m / s (kuyambira kum’mawa, pafupi ndi equator) ndikofunikira kwambiri.

Kufananaku kumafotokozanso mfundo ya ma stages oyamba omwe angagwiritsidwe ntchitonso: amayenda m’mbuyo pogwiritsa ntchito mafuta amene angagwiritsidwe ntchito pakupanga zonyamula, kugulitsa pang’onopang’ono pa kuchuluka kwa zonyamula kuti sizingawononge mbali yofunika kwambiri ya roketi.