Livros sobre o assunto:

1. Kenneth Munson. Helicopters and other rotorcraft since 1907. Littlehampton Book Services Ltd. 1973.

2. Robert Jackson. Helicopters: Military, Civilian and Rescue Rotorcraft. Grange Books. 2005.

3. Pedro Castillo, Rogelio Lozano, Alejandro E. Dzul. Modelling and Control of Mini-Flying Machines (Advances in Industrial Control). Springer. 2006. (página 39): https://www.google.com.br/books/edition/Modelling_and_Control_of_Mini_Flying_Mac/_aCpKOQgdYEC?hl=en&gbpv=1&dq=George%20de%20Bothezat&pg=PA39&printsec=frontcover

4. Helicopter Flying Handbook (FAA-H-8083-21A ed.). FAA. 2012. pp. 2-18–2-19.

5. Machado, Alessandro José. Conhecimento geral de helicópteros. Universidade do sul de Santa Catarina. https://cdn.hackaday.io/files/9638412352192/0000035D.pdf

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Artigos sobre o assunto:

1. J. Gordon Leishman; Bradley Johnson. Engineering Analysis of the 1907 Cornu Helicopter. Department of Aerospace Engineering. Glenn L. Martin Institute of Technology. University of Maryland: 

2. Hirschberg, Michael J. “A Perspective on the First Century of Vertical Flight.” SAE Transactions 108 (1999): 1113–36. http://www.jstor.org/stable/44729509

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Patentes:

1. Helicóptero de Bothezat: https://patents.google.com/patent/US1573228A/en?oq=US1573228+

2. Direct lift aircraft. Igor Sikorsky (1931): https://patents.google.com/patent/US1994488A/en?oq=US1994488A

3. Todas as patentes de Igor Sikorsky: https://patents.google.com/?inventor=Igor+I+Sikorsky

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Sites:

1. Leonardo da Vinci’s helicopter: 15th-century flight of fancy led to modern aeronautics. https://theconversation.com/leonardo-da-vincis-helicopter-15th-century-flight-of-fancy-led-to-modern-aeronautics-116241

2. History of the Helicopter from Concept to Modern Day. https://primeindustriesusa.com/history-of-the-helicopter/

3. Vórtices formados em uma pá de um helicóptero durante a rotação: https://www.nas.nasa.gov/SC15/demos/demo5.html

4. Helicopter- Invented by Igor Sikorsky. http://www.edubilla.com/invention/helicopter/

5. Enrico Forlanini’s experimental helicopter, detail: https://artsandculture.google.com/asset/enrico-forlanini%E2%80%99s-experimental-helicopter-detail/FAGGk-pZ_aWCOA

6. Desenvolvimento de helicópteros no início do século XX: https://web.archive.org/web/20120505230212/http://www.centennialofflight.gov/essay/Rotary/early_20th_century/HE2.htm

7. A invenção de De Bothezat sendo saudada por Thomas Edison como "o primeiro helicóptero de sucesso": https://time.com/vault/issue/1923-03-03/page/23/

8. Recorde de Étienne Oehmichen: https://www.fai.org/records?record=Oehmichen

9. Recorde de Pateras Pescara: https://www.fai.org/records?record=Pescara

10. Recorde do piloto Maurice Claisse com o helicóptero Bréguet-Dorand Gyroplane Laboratoire: https://www.fai.org/records?record=Maurice+claisse

11. Recorde do piloto Karl Bode com o helicóptero alemão FW-61: https://www.fai.org/records?record=Karl+Bode

12. Dissimetria de sustentação: https://stringfixer.com/pt/Dissymmetry_of_lift

13. Helicóptero S-46 / VS-300 / VS-300A: https://www.sikorskyarchives.com/S-46%20_VS-300_%20VS-300A.php

14. VS-300 Helicopter: https://sikorskyarchives.com/VS-300_Helicopter.php

15. VS-300 Helicopter (documentos históricos): https://sikorskyarchives.com/VS-300_Helicopter%20n.php

16. Vought-Sikorsky XR-4C: https://www.si.edu/object/vought-sikorsky-xr-4c%3Anasm_A19600307000

17. Reportagem da Times sobre o helicóptero de George de Bothezat https://time.com/vault/issue/1923-03-03/page/23/

18. Reportagem (1935) sobre o Bréguet-Dorand Gyroplane Laboratoire onde consta a potência do motor de 350hp: https://gallica.bnf.fr/ark:/12148/bpt6k6555250x.r=Br%C3%A9guet%20Gyroplane?rk=21459;2

19. Reportagem (1936) sobre Bréguet-Dorand Gyroplane Laboratoire onde consta a velocidade máxima de 120km/h: https://www.retronews.fr/journal/le-phare-de-la-loire/22-decembre-1935/1761/3132655/1

20. Aula de aerodinâmica do helicóptero: https://www.youtube.com/watch?v=S0viIHbNDgo&list=PLNViT7oNkRSWHXkCpQM_H4BYoLb_lOgzy&index=5

21. BELL 47G-2 (H-13H) “Sioux” | Bell Helicopter Corporation: https://www2.fab.mil.br/musal/index.php/aeronaves-em-exposicao/55-avioes/389-h-13h

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Consultas realizadas na wikipedia, com muito bom senso é claro:

1. Helicóptero: https://en.wikipedia.org/wiki/Helicopter

2. Gustave d'Amécourt (1861): https://pt.wikipedia.org/wiki/Gustave_d%27Am%C3%A9court

3. Enrico Forlanini: https://en.wikipedia.org/wiki/Enrico_Forlanini

4. Antoinette (fabricante): https://en.wikipedia.org/wiki/Antoinette_(manufacturer)

5. Antoinette: https://pt.wikipedia.org/wiki/Antoinette

6. Bréguet-Richet Gyroplane (1907): https://en.wikipedia.org/wiki/Br%C3%A9guet-Richet_Gyroplane

7. Paul Cornu: https://pt.wikipedia.org/wiki/Paul_Cornu

8. Paul Cornu: https://en.wikipedia.org/wiki/Paul_Cornu

9. De Bothezat helicopter (1922): https://en.wikipedia.org/wiki/De_Bothezat_helicopter

10. Motor rotativo: https://en.wikipedia.org/wiki/Rotary_engine

11. George de Bothezat: https://en.wikipedia.org/wiki/George_de_Bothezat

12. Rotary engine (motor rotativo): https://en.wikipedia.org/wiki/Rotary_engine

13. Étienne Oehmichen: https://en.wikipedia.org/wiki/%C3%89tienne_Oehmichen

14. Raúl Pateras Pescara (1921-1924): https://en.wikipedia.org/wiki/Ra%C3%BAl_Pateras_Pescara

15. Juan de La Cierva y Codorniu: https://pt.wikipedia.org/wiki/Juan_de_La_Cierva_y_Codorniu

16. Juan de La Cierva y Codorniu: https://es.wikipedia.org/wiki/Juan_de_la_Cierva

17. Dissimetria de sustentação: https://en.wikipedia.org/wiki/Dissymmetry_of_lift

18. Bréguet-Dorand Gyroplane Laboratoire: https://en.wikipedia.org/wiki/Br%C3%A9guet-Dorand_Gyroplane_Laboratoire

19. Bréguet Aviation: https://en.wikipedia.org/wiki/Br%C3%A9guet_Aviation

20. Bréguet-Dorand Gyroplane Laboratoire: https://en.wikipedia.org/wiki/Br%C3%A9guet-Dorand_Gyroplane_Laboratoire

21. Focke-Wulf Fw 61: https://pt.wikipedia.org/wiki/Focke-Wulf_Fw_61

22. Focke-Achgelis Fa 223: https://en.wikipedia.org/wiki/Focke-Achgelis_Fa_223

23. Henrich Focke: https://en.wikipedia.org/wiki/Henrich_Focke

24. Igor Sikorsky: https://en.wikipedia.org/wiki/Igor_Sikorsky

25. Vought-Sikorsky VS-300: https://en.wikipedia.org/wiki/Vought-Sikorsky_VS-300

26. Sikorsky R-4: https://en.wikipedia.org/wiki/Sikorsky_R-4

27. Sikorsky R-6: https://pt.wikipedia.org/wiki/Sikorsky_R-6

28. United Technologies Corporation: https://pt.wikipedia.org/wiki/United_Technologies_Corporation

29. BELL 47G: https://en.wikipedia.org/wiki/Bell_47

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A maioria das imagens e vídeos estão em domínio público, são autorais de Invenções na História ou são cortesia de:

Vídeos (Ampliados e restaurados utilizando Inteligência Artificial):

[A/V Geeks - Shell oil Company] History of the Helicopter (1952) (em domínio público): https://www.youtube.com/watch?v=83mGUnEsyF4

[U.S. Navy] U.S. Sailors and Marines Participate In Visit Board Search and Seizure Training: https://www.youtube.com/watch?v=SiSuUxg7yY0

[illustratormartin] Leonardo Da Vincis Helicopter Part2: https://www.youtube.com/watch?v=NPoV_vnidhw&t=1s

[VilleMontbeliard]. Interview d'Etienne Oehmichen, fondateur de l’hélicoptère: https://youtu.be/NrW3h3bvwPU

[EYE at Open Beelde via Wikimedia Commons]. Helicóptero de Pescara - Bits & Pieces - BP374 - Test flight of Pescara's helicopter - 1922 - EYE FLM7760 - OB105716.ogv:  https://commons.wikimedia.org/wiki/File:Bits_%26_Pieces_-_BP374_-_Test_flight_of_Pescara%27s_helicopter_-_1922_-_EYE_FLM7760_-_OB105716.ogv

[PublicResourceOrg]. HELICOPTER ORIENTATION - INTRODUCTION TO HELICOPTERS: https://youtu.be/xb05PyrvkAE

[PublicResourceOrg]. How Airplanes Fly (Como os aviões voam): https://www.youtube.com/watch?v=ocni_Whz5EA

[PublicResourceOrg]. AIR FORCE STORY, THE -- SUPERFORT, AUGUST 1943-JUNE 1944: https://www.youtube.com/watch?v=0ppMTANZolQ&t=731s

1937 Germany, Aviation 250188-09 | Footage Farm (em domínio público): https://www.youtube.com/watch?v=tjWH7D1rgCk

[Royal Aeronautical Society via National Aerospace Library]. Sikorsky XR-4: https://www.youtube.com/watch?v=Ff1TL5Fedog

[Royal Aeronautical Society via National Aerospace Library]. Sikorsky helicopters: https://www.youtube.com/watch?v=IioKuVUqhNA

[Royal Aeronautical Society via National Aerospace Library Sikorsky VS-300A and Sikorsky XR-4: https://www.youtube.com/watch?v=r0i1JD2sGvM

Hitler’s Secret Weapons 7/10 - 300315X | Footage Farm Ltd (em domínio público):https://www.youtube.com/watch?v=qQTkWWWBbOQ

[PublicResourceOrg]. HISTORY OF AVIATION - PART 1 (Igor sikorsky falando): https://www.youtube.com/watch?v=jXPzwTgINss

Sikorsky Helicopter Demonstrated - 250190-01 | Footage Farm Ltd. https://www.youtube.com/watch?v=hTDu6fs7VUI

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Imagens (Ampliadas e restauradas utilizando Inteligência Artificial):

[Museo Galileo - Istituto e Museo di Storia della Scienza]. Leonardo da Vinci, Manuscript B f 83 v: https://artsandculture.google.com/culturalinstitute/beta/u/1/asset/leonardo-da-vinci-manuscript-b-f-83-v/hgEHtqnKGl4gjw

Aerial screw Da Vinci: https://commons.wikimedia.org/wiki/File:Aerial_screw_Da_Vinci.jpg

Gustave d'Amécourt (Imagem ampliada e colorida por Invenções na História utilizando com inteligência artificial): https://upload.wikimedia.org/wikipedia/commons/0/0c/Gustave_de_Ponton_d%27Am%C3%A9court.png

[Imagem ampliada e colorida por Invenções na História] A "hélice de Amécourt", fotografada por Nadar:https://commons.wikimedia.org/wiki/File:Chere_helice.jpg

[wikimedia] Enrico Forlanini (Imagem ampliada e colorida por Invenções na História utilizando com inteligência artificial): https://en.wikipedia.org/wiki/File:Enrico_Forlanini.jpg

[wikimedia - Museu Nacional da Ciência e Tecnologia Leonardo da Vinci.] Elicottero sperimentale Enrico Forlanini Museo scienza e tecnologia Milano 01.jpg: https://commons.wikimedia.org/wiki/File:Elicottero_sperimentale_Enrico_Forlanini_Museo_scienza_e_tecnologia_Milano_01.jpg

[wikimedia - Museu Nacional da Ciência e Tecnologia Leonardo da Vinci.] Elicottero sperimentale Enrico Forlanini Museo scienza e tecnologia Milano 03.jpg: https://commons.wikimedia.org/wiki/File:Elicottero_sperimentale_Enrico_Forlanini_Museo_scienza_e_tecnologia_Milano_03.jpg

[wikimedia - Museu Nacional da Ciência e Tecnologia Leonardo da Vinci] Elicottero sperimentale Enrico Forlanini 1877 Museo scienza e tecnologia Milano.jpg: https://upload.wikimedia.org/wikipedia/commons/d/d7/Elicottero_sperimentale_Enrico_Forlanini_1877_Museo_scienza_e_tecnologia_Milano.jpg

[wikipedia - Museu Nacional da Ciência e Tecnologia Leonardo da Vinci] Motor Antoinette V8 aircraft: https://en.wikipedia.org/wiki/Antoinette_(manufacturer)#/media/File:Antoinette_8V_side_cropped_Museo_scienza_e_tecnologia_Milano.jpg

[gallica.bnf.fr / Bibliothèque nationale de France] 14-bis de Alberto Santos Dumont: https://gallica.bnf.fr/ark:/12148/btv1b8433366m/f32.item

[gallica.bnf.fr / Bibliothèque nationale de France]. Helicoptero de Cornu: https://gallica.bnf.fr/ark:/12148/bpt6k5326840d/f12.item.r=Paul%20Cornu.zoom

[Wikimedia]. Breguet Gyroplane 1907: https://commons.wikimedia.org/wiki/File:Breguet_Gyroplane_1907.jpg

[Musée des arts et métiers-Cnam/photo Michèle Favareille]. Breguet-Richet no. 1 gyroplane: https://artsandculture.google.com/asset/breguet-richet-no-1-gyroplane-louis-breguet/JwH1CFNu44563Q

[gallica.bnf.fr / Bibliothèque nationale de France]. Louis Breguet, in 1909: https://en.wikipedia.org/wiki/Louis_Charles_Breguet#/media/File:Louis_Charles_Breguet.jpg

[gallica.bnf.fr / Bibliothèque nationale de France]. Louis Breguet: https://gallica.bnf.fr/ark:/12148/bpt6k76254507/f1.item.r=Br%C3%A9guet-Richet.zoom

[Família de Cornu via Wikimedia]. Paul-Cornu.jpg: https://commons.wikimedia.org/wiki/File:Paul-Cornu.jpg

[National Air and Space Museum via Wikimedia]. Smithsonian Institution, National Air and Space Museum, Videodisc. 2B 5847, Public domain, via Wikimedia Commons. HE2G13.jpg: https://commons.wikimedia.org/wiki/File:HE2G13.jpg

[Família de Cornu via Wikimedia]. Paul-Cornu-1: https://commons.wikimedia.org/wiki/File:Paul-Cornu-1.jpg

[National Air and Space Museum via Wikimedia]. De Bothezat Flying Octopus: https://commons.wikimedia.org/wiki/File:De_Bothezat_Flying_Octopus.jpg

[National Park Service via Wikimedia]. De Bothezat Quadrotor: https://commons.wikimedia.org/wiki/File:De_Bothezat_Quadrotor.jpg

[gallica.bnf.fr / Bibliothèque nationale de France]. de Bothezat helicopter: https://gallica.bnf.fr/ark:/12148/bpt6k4605109v/f1.item.r=Bothezat%20helicopter.zoom#

[1000aircraftphotos via Ray Watkins Collection]. No. 8241. de Bothezat Helicopter: https://1000aircraftphotos.com/Contributions/WatkinsRay/8241.htm

[Library of Congress via Wikimedia]. Thomas Alva Edison, 1847-1931, left profile, seated at his desk, writing: https://commons.wikimedia.org/wiki/File:Thomas_Alva_Edison_I.png

[gallica.bnf.fr / Bibliothèque nationale de France]. Imagens de jornal mostrando o Oehmichen No 2: https://gallica.bnf.fr/ark:/12148/bpt6k97905066/f9.item.zoom#

[gallica.bnf.fr / Bibliothèque nationale de France]. Oehmichen No 2 ganha o prêmio de 90.000 francos franceses: https://gallica.bnf.fr/ark:/12148/bpt6k628815m/f1.item.r=Oehmichen.zoom

[gallica.bnf.fr / Bibliothèque nationale de France]. Capa da revista Le Petit Inventeur: https://gallica.bnf.fr/ark:/12148/bpt6k45270600/f1.item.r=helicopter%20invention.zoom#

[Christian de Pescara, archives personnelles via Wikimedia]: L'hélicoptère Pescara 2F fotografado em 29 de janeiro de 1924: 1924https://upload.wikimedia.org/wikipedia/commons/6/68/19_janvier_1924_R._Pateras-Pescara_pilote_le_2F.JPG

[Bundesarchiv via Wikimedia Commons]. Bundesarchiv, Bild 102-12592 / CC-BY-SA 3.0, CC BY-SA 3.0 DE <https://creativecommons.org/licenses/by-sa/3.0/de/deed.en>, via Wikimedia Commons: https://commons.wikimedia.org/wiki/File:Bundesarchiv_Bild_102-12592,_Schraubenflugzeug_beim_Senkrecht-Start.jpg

[Christian de Pescara, archives personnelles via Wikimedia]. Christian de Pescara, photo-montage de photos d'archives personnelles: https://commons.wikimedia.org/wiki/File:Le_Marquis_Raul_PATERAS_PESCARA_et_ses_2_H%C3%A9licopt%C3%A8res_2R_et_2F.JPG

[Narodowe Archiwum Cyfrowe via Wikimedia]. Avião de Cierva no Paris Air Show de 1934: https://commons.wikimedia.org/wiki/File:Paris_Air_Show_1934_Cierva.jpg

[Wikimedia]. Foto do Cierva: https://commons.wikimedia.org/wiki/File:Juan_de_la_Cierva,_Lasarte,_1930.jpg

[gallica.bnf.fr / Bibliothèque nationale de France]. Fotos do Bréguet-Dorand Gyroplane Laboratoire: https://gallica.bnf.fr/ark:/12148/bpt6k6555250x.r=Br%C3%A9guet%20Gyroplane?rk=21459;2

[gallica.bnf.fr / Bibliothèque nationale de France]. Reportagem com fotos do Bréguet-Dorand Gyroplane Laboratoire: https://www.retronews.fr/journal/le-phare-de-la-loire/22-decembre-1935/1761/3132655/1

[1000aircraftphotos via Ray Watkins Collection]. No. 8240. Breguet-Dorand Gyroplane Laboratoire: https://1000aircraftphotos.com/Contributions/WatkinsRay/8240.htm

[[1] Aquivo de Peter Kurze] Henrich Focke: https://www.kreiszeitung.de/lokales/bremen/hubschrauber-erfinder-henrich-focke-jahren-bremen-geboren-bedeutender-deutscher-ingenieur-5606724.html

[[2] Wikimedia]. Focke-Wulf Fw 61: https://commons.wikimedia.org/wiki/File:Fw_61_V.JPG

[German Federal Archive]. Reitsch in 1936 at Wasserkuppe: https://en.wikipedia.org/wiki/Hanna_Reitsch#/media/File:Bundesarchiv_Bild_183-W-0801-512,_Rh%C3%B6n,_Hanna_Reitsch_beim_Segelflug-Wettbewerb.jpg

[German Federal Archive / Imagem ampliada e colorida por Invenções na História]. Adolf Hitler awards Hanna Reitsch the Iron Cross 2nd Class in March 1941: https://en.wikipedia.org/wiki/Hanna_Reitsch#/media/File:Bundesarchiv_B_145_Bild-F051625-0295,_Verleihung_des_EK_an_Hanna_Reitsch_durch_Hitler.jpg

[Wikimedia]. Igor Sikorsky B&W.jpg: https://commons.wikimedia.org/wiki/File:Igor_Sikorsky_B%26W.jpg

[U.S. Coast Guard via Wikimedia Commons]. Igor Sikorsky in a U.S. Coast Guard HNS-1, 14 August 1944 (232-8): https://commons.wikimedia.org/wiki/File:Igor_Sikorsky_in_a_U.S._Coast_Guard_HNS-1,_14_August_1944_(232-8).jpg

[Library of Congress] Bain News Service, Publisher. Sikhorsky i.e., Sikirsky Aeroplane RUSSIAN KNIGHT, 1913. [Feb] Photograph. https://www.loc.gov/item/2014697436/.

[Library of Congress] Bain News Service, Publisher. Bailleul. , 1918. [Sept. 1] Photograph. https://www.loc.gov/item/2014708107/.

[SDASM Archives via Wikimedia Commons]. Sikorsky Russky Vityaz front with Nicholas II and Igor Sikorsky: https://commons.wikimedia.org/wiki/File:Sikorsky_Russky_Vityaz_front_with_Nicholas_II_and_Igor_Sikorsky_(5959299602)_(grayscale,_contrast_stretch).jpg

[SDASM Archives via Wikimedia Commons]. Sikorsky Russky Vityaz with Igor Sikorsky and others: https://commons.wikimedia.org/wiki/File:Sikorsky_Russky_Vityaz_with_Igor_Sikorsky_and_others_(5959299774)_(grayscale,_contrast_stretch).jpg

Entre tantas outras pesquisas que não lembrei de anotar aqui. Acredito que com estas referências, já consigo dar uma direcionada em quem tiver interesse de pesquisar sobre o tema.