Scifi: men travel through subterranean world, parachute down deep cavern

There's a book I read at school that I've been trying to find for 40 yrs to find out how the story ended! It was published before 1975 (which is when we read the book), and was a science-fiction story. All I can remember of the plot are the following:

It was possibly set in the 1940's,
there were maybe 3 or 4 main characters,
they may have been former WW2 airmen,
they were travelling in a subterranean world,
they came upon a deep cavern at one point, and used their parachutes to jump down a large, deep hole.
The descent took a significant portion of the story, as the hole was very, very deep.
I can't remember if this took place on earth, or on another planet (I think at some point they still had their plane in the caverns).
I vaguely remember a subterranean civilisation, but I can't remember what they were like.
The edition I read had b&w line drawings as illustrations.

Some of the details sound different, but could it be A strange manuscript found in a copper cylinder by James De Mille? I looked at the contents online and it has b&w drawings inside.

Description:
Four sailors discover a copper cylinder containing a manuscript written by the adventurer Adam More, who was shipwrecked in the southern hemisphere. They read its contents out to one another, and the incredible story unfolds of his journey through a subterranean tunnel to a lost world which survives at the foot of a volcano. This strange utopian society, in which humans coexist with prehistoric animals, is the antithesis of Victorian England, as poverty is preferred to wealth and darkness to light.

Bump.

The De Mille book was published in the 1880s so not likely to be the book given the protagonists are using parachutes.

Additionally the book described in this posting seems similar to the post by ColtenBrown: https://www.librarything.com/topic/323496#n7247467 so perhaps the two can compare details?

"In more detail, a pilot crash lands on an island. He has his parachute on and the sand around him sinks in and he finds himself on the edge of a big hole with clouds below him. He can't get back up to the island, so he jumps with his parachute down the hole."

List to check out: https://www.librarything.com/tag/hollow+earth,+science+fiction

Bump

Have you checked out Journey to the Center of the Earth by Jules Verne?

I was going to say sounds like a Jules Verne book to me, although the part about a hidden society co-existing with prehistoric animals makes me think of Dinotopia. Long shot.

Just possibly a Pellucidar story by Edgar Rice Burroughs. At least some of those are set between the World Wars. (Disclaimer: I'm not very familiar with the Pellucidar stories, Pellucidar being Burroughs' name for his hollow Earth setting.)

Savage Pellucidar has an aircraft in it that's compared to a parachute, although it was experimental and may have ended in disaster.

Burroughs also had a hollow Moon setting, starting with The Moon Maid, and which is set in an alternate history wherein World War I lasted for decades (he wrote it during the war). I don't think the story you're asking about is The Moon Maid itself, but it has sequels that I haven't read.

Thanks for the various suggestions. It is not Jules Verne or ERB as from what I remember reading them the means of reaching the underground was via parachute vs. how Verne and ERB had it completed. In the former it was via hiking through lava tubes. In the latter it was generally via the 'metal mole'. I have not read The Moon Maid but that is not it as it was a hollow Earth setting.

Additionally, given the phrasing, how the parachutes were used, etc. I agree this would have been written in the 40s or later. Most of ERB's work pre-dated that timing. One of the latest was the recommendation of Savage Pellucidar with the plane. But this was definitely focused on the chute and no plane was involved.

Thanks.

The first recorded parachute jump was in 1783, so that would cover quite a large part of the "Lost Race" and "Hollow Earth" story period. Perhaps not the earliest, but probably most of them. If you read this 40 years ago in High School, I would not think it was one of the older stories though, nor one of the more obscure ones. It may just be that you are writing off some that you should not be.

bump

>2 WhoNeedsSleep:, >3 beichst:, confirming it's not the DeMille, I've read that one and there's no parachutes.

bump

The Perilous Descent by Bruce Carter? Illustrated by Janet Duchesne. 1952.

https://en.wikipedia.org/wiki/Into_a_Strange_Lost_World

Thanks MissSquish. This is the book I was thinking of. I remember the cover.

@SchmuelP does this look like the one you are seeking?