(This post was originally intended to be published as an article in Ufologist Magazine, but unfortunately they have ceased publication.)
Ancient aliens believers claim there are descriptions of flying machines called vimanas and nuclear warfare in ancient Indian texts. These claims first appeared in the 1953 book Flying Saucers Have Landed by Desmond Leslie and George Adamski .
In a blog articles “Vimana Aircraft of India: More Sloppy Scholarship from David Childress”, Jason Calovito explains the origin of the word “vimana”,
“The word vimana means “that which was measured out”. The word was first applied to the palace of the monarch, and from that to temples. Because temples are the houses of the gods, the Hindu gods’ palaces could also be called vimanas. In the oldest texts the Vedas, these were drawn by flying horses, like the chariot of the sun god in most Indo-European cultures (see, for example, the myth of Phaethon.) In later epics, beginning with the Ramayana (c. 500 BCE), the chariots lost their horses and were flying on their own. The very first of these is the flying chariot of the earthly king Ravana called Pushpaka. By the time of the Mahabharata (c. 400 BCE), these flying machines had grown in size – one was now described as 12 cubits in circumference – but they never lost the large wheels that marked them as derived from earthly horse-drawn chariots.”
Because vimanas came to mean both Indian temples and the flying palaces of the gods, the flying vimanas were usually portrayed as having the same tall trapezoid shape as Indian temples, which do not appear at all aerodynamic.
As mentioned before, historians tend to regard earlier sources as more reliable because they have not become embellished over time, but ancient aliens believers tend to rely on the later sources which are less reliable and bear less resemblance to the original events if they happened at all.
The Ancient Aliens episode “The Evidence” claims that there are “ancient Sanskrit texts dating back as far as 6000 BC describing in vivid detail flying machines called vimanas.”
Actually, there were no Sanskrit speakers in India in 6000 BC. Instead of showing us any of these supposed 8000 year old texts, Ancient Aliens proceeds to show us illustrations from the Vimanika Shastra . This is not an ancient text. It was channelled by Pandit Subraaya Sastri between 1918 and 1923 . One would not learn this from Ancient Aliens who give their audience the impression this is an ancient text.
In 1974 the Indian Institute of Science published a study of the Vimanika Shastra and concluded that the aircraft described in the text could not have flown and it was apparently written by someone who did not understand aerodynamics;
“None of the planes has properties or capabilities of being flown; the geometries are unimaginably horrendous from the point of view of flying: and the principles of propulsion make them resists rather than assist flying.” 
In Weapons of the Gods Nick Redfern comments,
“There’s no doubt, however, that everything that ahs been circulated about vimanas – as fast-flying vehicles equipped with atomic bombs – does not come from the pages of the Mahabharata, even though that is clearly the assumption of many. It is an outgrowth and expansion on the words of an Indian mystic who, in the early 20th century, received messages in his mind from paranormal entities.” 
An authentic Indian text which mentions vimanas is the Samarangana Sutradhara, an 83 chapter treatise on Indian architecture and engineering, which was written by King Bhoja of Dhar (1010 -1055 AD). Chapter 31 discusses yantras, which can be translated as mechanical contrivances or machines, including two types of vimanas. The Laghu Dharu vimana was made of wood and shaped like a bird and had a pilot. It was powered by heating mercury which caused its wings to flap and fly. The Alaghu Dharu vimana was also made of wood and shaped like a temple, with a wooden car flying alongside. It was also powered by heating mercury and was used to scare war elephants
Bhoja assumed that an aircraft would fly by flapping its wings, much in the same way some people before the Wright Brothers assumed it was possible to fly by imitating birds and flapping man-made wings. This suggests they had no real experience with actual flying machines. Likewise, if the ancient Indians really did use vimanas for military purposes, they would surely do more than just scare elephants, such as dropping bombs.
The episode “The Evidence” also suggests that there was a “worldwide transportation system” and vimanas flew around the world in ancient times and landed at Nazca in Peru and on top of Masada in Israel . (The Nazca lines which some ancient aliens believers claim are runways, will be discussed in the next issue.) However, accounts of tall trapezoid-shaped flying machines can only be found in India, where they resemble the local temples. If they did fly around the world, surely we would expect there to be similar descriptions from elsewhere in the ancient world.
Likewise, Ancient Aliens do not explain why vimanas would need runways to land in Peru, but not in India.
In 2010 there were reports that a vimana had been discovered in Afghanistan and eight American soldiers had disappeared trying to remove it. Even David Hatcher Childress described these claims as “dubious” . In fact, this story seems to be based on a 2007 film The Objective about a patrol of America soldiers which disappears while looking for vimanas in Afghanistan. The Objective was directed by Daniel Myrick who co-directed The Blair Witch Project which also confused some people about what was real.
Nuclear war in the Mahabharata
The Mahabharata is an ancient Indian epic which is about 1.8 million words long and divided into 18 parvas or books. It tells the story of the struggle between two branches of a family, the Kaurava and the Panndava, for the throne of Hastinapura in northern India. This culminated in the Battle of Kurukshetra around Haryana which lasted for 18 days. Ancient aliens believers claim that the Mahabharata described the use of nuclear weapons during this battle.
In his book Vimanas, Flying Machines of the Ancients, David Hatcher Childress claims this is a passage from Karna Parva (Book 8) of the Mahabharata which describes a nuclear explosion,
“Gurkha, flying in his swift and powerful vimana, hurled against the three cities of the Vrishnis and Andhakas a single projectile charged with the power of the Universe. An incandescent column of smoke and fire, as brilliant as ten thousand suns, rose in all its splendour … it was an unknown weapon, an iron thunderbolt, a gigantic messenger of death, which reduced to ashes the entire race of the Vrishnis and the Andhakas, …The corpses were so burned as to be unrecognizable. The hair and nails fell out; Pottery broke without cause; And the birds turned white .. after a few hours all foodstuffs were infected … to escape the fire the soldiers threw themselves in streams to wash themselves and their equipment.” 
However, in Ancient Atom Bombs Jason Colavito shows that his passage is a combination of three separate passages. One passage is a vision which did not come true. The reference to hair and nails falling out is meant to sound like the effects of radiation poisoning, but it takes place three decades after the battle and actually says that rats and mice ate their hair and nails. This invented passage has been quoted by numerous ancient aliens believers who clearly have not checked the original source .
In Chariots of the Gods? von Daniken quotes another passage from the Mahabharata which he claims is describing a nuclear explosion,
“It was as if the elements had been unleashed. The sun spun round. Scorched by the incandescent heat of the weapon, the world reeled in fever. Elephants were set on fire by the heat and ran to and fro in a frenzy to seek protection from the terrible violence. The water boiled, the animals died, the enemy was mown down and the raging of the blaze made the trees collapse in rows as in a forest fire. The elephants made a fearful trumpeting and sank dead into the ground over a vast area. Horse and war chariots were burnt up and the scene looked like the aftermath of a conflagration. Thousands of chariots were destroyed, then deep silence descended on the sea. The winds began to blow and the earth grew bright. It was a terrible sight to see. The corpses of the fallen were mutilated by the terrible heat so that they no longer looked like human beings. Never before have we seen such a ghastly weapon and never before have we heard of such a weapon.” 
His account is admittedly unusual, but it does not sound like a description of a nuclear explosion. There is intense heat, but there is no blast wave. If elephants were close enough to the explosion to be set on fire, they would not be able to run around. They would also have been crushed by the blast wave and the trees, which caught fire, would have been knocked down by the blast wave.
Moreover, von Daniken left out part of this passage which reads,
“From all points of the compass, cardinal and subsidiary, from the firmament and the very Earth, showers of sharp and fierce arrows fell and issued, with the impetuosity of Garuda or the wind. Struck and burnt by the shafts of Acwatthamn that were all endued with the impetuosity of the thunder, the hostile warriors fell down like trees burnt by a raging fire.” 
This is not an account of a nuclear warhead exploding. It is describing a mass of flaming arrows raining down from all directions. They burn things, but there is no explosion or blast wave .
The ancient aliens movement would have us believe that aliens gave nuclear weapons to primitive humans to settle a family feud. Quite frankly, this does not strike me as particularly responsible. There has never been an episode of Star Trek where the Federation discovers a planet where primitive humans are fighting among themselves, so they give them nuclear weapons.
During the 1920s archaeologists began excavating the ruins of Mohenjo-Daro, which was occupied from around 2500 to 1900 BC, in Sindh, Pakistan. The Ancient Aliens episodes “Alien Power Plant” and “The Alien Agenda” claim that the city was destroyed by a nuclear explosion. Mohenjo-Daro is about 800 kilometres from Haryara where the Battle of Kurukshetra is supposed to have taken place, so any nuclear explosion would not be related to the events of the Mahabharata. In the footage, which Ancient Aliens show of Mohenjo-Daro, the walls are still about two to three metres high. They had not been knocked over by the blast wave of a nuclear explosion.
The episode “Alien Power Plants” also claims that radioactive skeletons were discovered in Mohenjo-Daro . An archaeologist Francis Taylor is supposed to have discovered these radioactive skeletons. Skeletons have been found at Mohenjo-Daro, but there is no evidence they are radioactive. Likewise, there is no evidence that there ever was an archaeologist Francis Taylor who excavated the site .
There is no denying that ancient Indian legends describe strange weapons and aerial vehicles. Ancient aliens believers assume that every myth and legend is true and meant to be taken literally, however it seems more likely they are just made-up stories. Jacques Vallee has suggested they are the ancient Indian equivalent of Star Wars .
 Desmond Leslie and George Adamski, Flying Saucers Have Landed, Werner Laurie, London, 1953, p 90-100
 Jason Colavito, “Vimana Aircraft of India: More Sloppy Research from David Childress”, http://www.jasoncolavito.com/blog/vimana-aircraft-of-india-more-sloppy-research-from-david-childress
 “The Evidence”. Ancient Aliens, History Channel, 2010, 15 min
 Ibid., 15-21 min
 David Hatcher Childress, Vimana, Flying Machines of the Ancients, Adventures Unlimited Press, Illinois, 2013, p 134
 H.S. Mukundas, et al., “A Critical Study of the Work Vymanika Shastra”, Scientific Opinion, 1974, p 11
 Nick Redfern, Weapons of the Gods, New Page Books, New Jersey, 2016, p 77-78
 “The Evidence”. op cit., 22-26 min
 Vimina, Flying Machines of the Ancients, op cit., p 218
 Ibid., p 27-28
 Erich von Daniken, Chariots of the Gods?, Corgi, London, 1972, p 80
 Ancient Atom Bombs, op cit., p 8-9
 Ibid., p 9
 “Alien Power Plants”, Ancient Aliens, History Channel, 2013, 31-32 min
 “The Alien Agenda”, Ancient Aliens, History Channel, 2015, 9-16 min
 “Alien Power Plants”, op cit., 31-32 min
 Weapons of the Gods, op cit., p 93-95
 Jacques Vallee and Chris Aubeck, Wonders in the Sky, Jeremy P, Tarcher/Penguin, New York, 2009, p 363