Military Orions (nuclear pulse propulsion)

[agricola64]

we can substitute the nuclear bombs previously used for the atmospheric stage of the flight for thermobaric bombs (FAB) like the Russian Father Of All Bombs (FOAB) since these have the same power as a small nuclear bomb but with no fallout

It's not raw power that matters, it's power per unit weight. FOAB has a mass of several tonnes - assuming Wikipedia is correct (the numbers seem to be referenced), 7 tons for 44 tons yield. Offhand, a multi-kiloton nuclear device will have a mass of a couple of hundred kilograms.

RP1

the only point where i could see chemical propellant used in an orion flight system would be if you insist on take off from ground without using chemical rockets for intal lofting ..

place the orion over a deep pit, fill it half with a few thousand tons of AMFO, ignite .. this might reduce fall out since the next pulse (the first nuclea pulse) would be already a little away from ground ..

but it is a silly application .. putting a few SRB boosters underneath would do the same thing at better performance

 

[Orionblamblam]

In practice, would the 2nd stage shock absorbers be enclosed in a shroud to protect them from space debris?

There would be individual meteoroid shields. That's why the upper portions of the tubes are so much larger in diameter than the pistons... they housed telescoping shields. Once the propulsion system was shut down, the shields would extend from the upper tubes to enclose te pistons. The first stage shock absorber "airbags" would be depressurized, and the plate pulled in tight against the intermediate platform to "hide" the airbags.

 

[Orionblamblam]

one thing i did not understand about the battleship orion reconstruction was the complex launcher system for the Casaba Howitzer with aimed launch tubes

What I tried to do was rationalize the design as described. Sadly, the description of the CH's was exceptionally vague, but both written and verbal descriptions of the CH's mention some sort of noticable "emplacements." Were they simple VLS-like launch ports.... as I did with the Minuteman warheads - then they would not really stand out.

Secondly, the presumption is that the safest place to be around a detonating CH would be directly behind it, as opposed to off to the side. This may, of course, not be accurate... for all I know there were weird "lobes" in the blast. If you fired straight out of a fixed tube and then oriented, the bomb would present some side aspect to the Orion. But if you directed the CH away from the ship with an aimable launcher, the chances are greater that the bomb will have to change its attitude much less prior to detonation, keeping the Orion more directly behind it.

Thirdly, with an aimable launcher, most of the important attitude control will be done by the launcher itself. The onboard ACS will be needed for fine control. But if launched from a fixed tube, the onboard ACS will have to do both coarse and fine attitude control. This will be both heavier and less reliable. An aimable "bazooka" should be pretty reliable.

Until more info on CH comes out (any decade now, I'm sure), this is all specualtion

 

[sferrin]

Something else to keep in mind is the timeframe the thing was conceived. Back in those days the only thing they used a VLS for was SLBMs. Everything else used trainable launchers (except for a few Russian launchers on the Kara and Krest II classes) so it would stand to reason they'd be in that mindset. Besides, you also have to remember that in space there's no atmosphere for wings to work with so any change in direction would have to come from onboard fuel which would increase the weight. Much simpler to train it in the direction of the target and fire so any course corrections are kept to a minimum.

 

[agricola64]

Secondly, the presumption is that the safest place to be around a detonating CH would be directly behind it, as opposed to off to the side. This may, of course, not be accurate... for all I know there were weird "lobes" in the blast. If you fired straight out of a fixed tube and then oriented, the bomb would present some side aspect to the Orion. But if you directed the CH away from the ship with an aimable launcher, the chances are greater that the bomb will have to change its attitude much less prior to detonation, keeping the Orion more directly behind it.

Thirdly, with an aimable launcher, most of the important attitude control will be done by the launcher itself. The onboard ACS will be needed for fine control. But if launched from a fixed tube, the onboard ACS will have to do both coarse and fine attitude control. This will be both heavier and less reliable. An aimable "bazooka" should be pretty reliable.

Until more info on CH comes out (any decade now, I'm sure), this is all specualtion

not necessarily ..

the idea is a little hard to explain without being able to draw on a sheet of paper, but consider this

the CH us ejected and reorients itself towards the target, then inites its engine for separation (this implies that the target is in the hemisphere visible from the VLS location on the orion)

now draw a line from the orion to the target - the threat axis .. after reorientation and igniting the CH will follow a course that is parallel to the thrweat axis, offset by the ragius (and a little something) of the orion

if the detonation safety distance is large enoug (lets say at least 100 times the radius of the orion) the gemetry beomes a very narrow trinagle with almost no difference between the threat axis and the line of view from orion to the CH .. the orion basicaly IS seeing the back end of the CH exclusively ..

i hope the explanation is clear ..

i do understand the idea of minimising the ACS role - it will use less fuel .. otoh it is there already and making the tank a little larger will very likely still be lighter then the mechanics of the launcher

 

[Orionblamblam]

the CH us ejected and reorients itself towards the target, then inites its engine for separation

This would require two separate propulsion systems... an ejector (likely either a cold or hot gas "gun" on the ship) and a warhead-based system. What I assumed in mine was a fast-acting hot gas thruster that operates entirely within the confines of the launch tube. In that case, any thrust misalignments or CG issues become moot, as those side forces are taken up by the launch tube... not expended in throwing the warhead off course.

i do understand the idea of minimising the ACS role - it will use less fuel .. otoh it is there already and making the tank a little larger will very likely still be lighter then the mechanics of the launcher

Maybe, maybe not. Without going through the whole design and optimization process, and numbers woudl be the purest unwarranted speculation. But if you have six CH launchers and, say, a hundred CH warheads on board, that's about seventeen warheads per launcher. So if the additional complexity of an aimable launcher is, say, 500 pounds, then to match the same total weight the additional weight for the more-capable-ACS warheads would be 29 pounds. Given that the CH warheads are almsot certainly very dense little nuggets weighing on the order of 500 pounds, in order to provide the sort of attitude control required might easiy add another 30 pounds. Remember, it's not just slightly larger fuel tanks, it's also substantially higher thrust (thus larger & heavier) thrusters, plumbing and power systems (and very likely larger nitrogen pressurization systems).


In general terms, if you have a large, fixed emplacement (such as a battleship), what you'd generally prefer if to have a weapons system that keeps the expensive and complex stuff on the ship, and chucks simple&stupid at the enemy. That's what you have with a gun... a complex, heavy item that stays behind. Even with missile systems, you generally try to leave as much of the complexity on the ship as possible... the most complex weapons, such as the Standard missile that was recently used to take out a satellite, leaves most fo the tracking functions to the ship, and only carries what it absolutely *needs.*

But... who knows. Hopefully someday we'll know for sure. Very likely if i ever do see photos of the Orion battleship model and/or diagrams of the complete CH weapons system, my reaction will be one of "Huh."

 

[Orionblamblam]

Something else to keep in mind is the timeframe the thing was conceived. Back in those days the only thing they used a VLS for was SLBMs. Everything else used trainable launchers (except for a few Russian launchers on the Kara and Krest II classes) so it would stand to reason they'd be in that mindset.

Back In The Day:

The missiles were stored vertically and rose up from below the launchers... you can see the doors to either side of the pedestal.

Today:

The missiles are launched straight out of the tubes.

My bet is that in 1960, the Orion was designed with 1960-era practices. Were the design done today, or the Orion battleships refitted today, they'd use more modern design practices.

 

[sferrin]

Yep. Well aware of how they use to do it and how they do it today.

 

[chimeric oncogene]

Would a similar gas launch system been used to toss out the warhead RVs?

If the Orion was used as a gargantuan MIRV bus (instead of carrying smaller MIRV buses, which might also work but would cost more), one would imagine that it would need a helluva precise altitude control system and RV launcher (can you make a gas gun with low acceleration and very precise adjustable muzzle velocity?) to put warheads on target with reasonable accuracy (100-300m CEP?). Would unguided rockets work equally well (methinks not, but I know but little)? Or would Orion just stick a warhead out on an arm, let go, and maneuver?

The same question could be asked of the DynaSoar bomber, or the AXE Pershing II hypersonic glide vehicle airfield attack weapon.

How were the nuclear RVs proposed to be ejected from the Orion battleship?

 

[flateric]

Andrei Stanavov on Instagram: "Сразу оговорюсь, это не плод моего больного воображения, а взрыволет Orion battleship - нереализованный проект начала 60-х. Не успел наш Юра слетать в космос, как американцы придумали нечто, от чего волосы стынут в жила

Andrei Stanavov shared a post on Instagram: "Сразу оговорюсь, это не плод моего больного воображения, а взрыволет Orion battleship - нереализованный проект начала 60-х. Не успел наш Юра слетать в космос, как американцы придумали нечто, от чего волосы стынут в жилах. Ядерный, мать его...

www.instagram.com

 

[sferrin]

 

[publiusr]

Something else to keep in mind is the timeframe the thing was conceived. Back in those days the only thing they used a VLS for was SLBMs. Everything else used trainable launchers (except for a few Russian launchers on the Kara and Krest II classes) so it would stand to reason they'd be in that mindset.

Back In The Day:

The missiles were stored vertically and rose up from below the launchers... you can see the doors to either side of the pedestal.

Today:

The missiles are launched straight out of the tubes.

My bet is that in 1960, the Orion was designed with 1960-era practices. Were the design done today, or the Orion battleships refitted today, they'd use more modern design practices.

Still, having them on rails might allow inspection. A sealed outer door…some clusters. I might want to attack tail first…still have some rocket capability.

 

[RanulfC]

Considering the idea was for them to be "space" based ICBM carriers the essential idea as they would spit them out of the tubes and the missiles would orientate and then fire up to drop on Earth.

Randy

 

[Christopher Wang]

Hi everybody

To Orionblamblam: Thanks for your reply !
After I read some Websites, I am very confused !

The Continent Buster
What is it ?
Is it only a very big nuclear bomb or a nuclear rocket carrier like the 12m Orion Bomber ? (or both)
Is it a 1650 ton vehicle or a 4000 ton vehicle ?
Any dimensions known ?
What is a Casana-Howitzer ? (The Pusher-Plate as Weapon ? )
The 1650ton Continent Buster is only the payload of a 4000ton Orion vehicle ?

"The so called continent buster would have been much less effective than a cluster of lesser bombs. The greatest part of the force of the explosion would have been lost in space."
Why ? Is the continent buster only a big nuclear bomb ?

Here the 12m Orion Bomber

Damon Moran Technical Illustrations

damonmoran.blogspot.com

Here the USAF 4000ton orbital platform

https://flic.kr/p/q5so6

View: http://www.flickr.com/photos/xeni/272465097/in/set-72157594329917915/

Are this the same ?

The Websites
http://www.make-digital.com/make/vol13/?pg=182 (Page 180-183)(Deep Space Force)

http://www.secretprojects.co.uk/forum/index.php/topic,3282.15.html

http://rhysy.plexersoft.com/orion/

Maybe we can answer some of my questions?

THANKS A LOT FOR HELP and Many greetings

Here is a larger 2064 x 1323 pixels version of the military Orion spacecrafts (http://www.projectrho.com/public_html/rocket/realdesigns2.php) as drawn by Damon Moran (http://damonmoran.blogspot.com/):

From Left to Right: 8-meter Emergency Command / Control; 10-meter Command / Control; and 12-meter Strategic Weapon Delivery

 

[XP67_Moonbat]

Just saw this on the Project Terminated group. It's supposedly a photo of the long-lost Battleship Orion model that spooked JFK.

Unfortunately my friend who posted it has always been kinda lousy at posting sources. So I did some digging and found the TwitX post it originated from:

https://twitter.com/x/status/1828478385711968640

View: https://x.com/LIM49Spartan/status/1828478385711968640

 

[sferrin]

Just saw this on the Project Terminated group. It's supposedly a photo of the long-lost Battleship Orion model that spooked JFK.

Unfortunately my friend who posted it has always been kinda lousy at posting sources. So I did some digging and found the TwitX post it originated from:

https://twitter.com/x/status/1828478385711968640

View: https://x.com/LIM49Spartan/status/1828478385711968640

Project Terminated group?

 

[XP67_Moonbat]

Yes, indeed.

 

[publiusr]

It's supposedly a photo of the long-lost Battleship Orion model that spooked JFK.

View: https://x.com/LIM49Spartan/status/1828478385711968640

That’s up there with finding the three-footer from Star Trek if true.

They should have had a completely clad model with both American and Soviet flags…something like this:

Amazon.com

-but with an asteroid scare.

That could have made all the difference—

Orion just might have flown…

“‘President Kennedy let us turn swords into plowshares by having an Orion manned Moon mission with something with no Nazi ties to it…’ —that sound good Admiral Heinlein?

“Yeah—that sounds swell—put it on his desk right after he gets his shot from Dr. Feelgood….then take those flaps covering the missiles off and paint “USAF” all over it and leave it with LeMay to make sure it gets funded…in double quick time, or we’ll be late for Rickover’s funeral…what was that—Proxmire that hit him in a head-on? No great loss.”

If only

The Space Review: Starfleet was closer than you think

 

[Michel Van]

another version of that photo

https://twitter.com/x/status/1835245891537482189

View: https://twitter.com/Amaury_Dufay/status/1835245891537482189

 

[Scott Kenny]

What is a Casana-Howitzer ? (The Pusher-Plate as Weapon ? )

Casaba-Howitzer.

Based on what has been said in open documents, it's a weaponized Orion pusher charge or nuclear shaped charge. Instead of a thick tungsten plate that vaporizes into a 22deg cone, it uses a much lighter material like aluminum or even beryllium(!) in a thinner plate or even foil to focus down to less than 1.5deg. Not great collimation when you really want everything focused into more like a minute of angle (1/60 degree) or a milliradian, but when you're talking kilotons the wider beam helps with inaccuracies in predicted speed and course. Plus, it's supposedly throwing some 85% of the total nuclear blast energy into that tiny cone.

If you fired one on earth, it'd blast a hole through solid rock for thousands of miles.

i just got the APR .. thnak you, orionblamblam for a very interesting issue

..............

one thing i did not understand about the battleship orion reconstruction was the complex launcher system for the Casaba Howitzer with aimed launch tubes .. the follwing is not a critism, just a question to understandt the rationale for the system chosen in the reconstuction

since a Casaba Howitzer round needs to have an attitude control system (acs) for aiming and a rocket engine for launch why not using it to launch it from fixes tubes .. either one-shot VLS or a reloadable "torpedo tube"

lauch from tube with a small gas generator, use acs to reorient for dispersal, fire rocket engine, coast a few seconds to get to safety distance from the orion, during the coast use the acs to reorient for aiming (that should give you enough time to get a stable aiming solution), initate bomb

this would eliminate the complex and prone to failure moving launch tube, keeping all the moving mechanical parts of the reload mechanism inside the ship where it can be serviced without a space suit - abd since the reload movements would also be simpler it might also speed up firing speed (no need for complex movents to align launcher tube with loading mechanism)

looking forward to your answers

My suspicion was that Casaba Howitzer charges would go through the usual propulsion charge launch system and get detonated on the far side of the pusher plate. As @Orionblamblam says, that's not ideal in terms of how much power you'd need to put into the reaction control system of the charge itself to aim. Using something like a USN Mk11 guided missile launcher would allow for offloading most of the coarse aiming onto the warship, which lets the charge itself just do final lineup.

Another weapon that would be usable by an Orion-drive warship would be x-ray lasers. Depending on how many X-rays are unused by the propulsion charge, it'd be possible to spit out a physically separate x-ray laser beam "crystal" in a pointable canister like the casaba howitzer, then follow it with either a propulsion charge or a plain nuke to get the x-rays flowing. This assumes a significant offset between the nuclear explosion that is the x-ray source and the laser unit. Other ideas for x-ray lasers (in the 1980s) bolted the laser rods directly onto the nuke.

 

[Dilandu]

Casaba-Howitzer

No. There is no such thing as Casaba Howitzer. It's an accidental mix of two real nuclear shaped charge weapon projects:

* Nuclear howitzer - a narrow plasma jet from nuclear shaped charge (i.e. what usually is considered "Casaba howitzer"

* Casaba project - a nuclear "shotgun", using nuclear shaped charge to propel metal shrapnel

The "deep space bombardment force" documents shows them as different weapons.

 

[publiusr]

Any leads on the whereabouts of the model?

Let me guess…in a storage unit.

Can we not clean this one with Pine-Sol?

 

[Firefinder]

No. There is no such thing as Casaba Howitzer. It's an accidental mix of two real nuclear shaped charge weapon projects:

* Nuclear howitzer - a narrow plasma jet from nuclear shaped charge (i.e. what usually is considered "Casaba howitzer"

* Casaba project - a nuclear "shotgun", using nuclear shaped charge to propel metal shrapnel

The "deep space bombardment force" documents shows them as different weapons.

You slightlt wrong there boss.

Both those projects Originally felled under the Projects Casaba Howitzer.

Which had to do with ALL the weaponize versions of Project Orion pulse modules.

The Nuclear shape charge beam of doom?

Casaba Howitzer

Nuclear EFP? The Shotgun?

Same.

This was the Project, which has both budget docs and personal statements, which made those.

Even the 1980s SDI refers to theses weapons, specifically the beam one, as Casaba Howitzers

And it very much existed.

A whole lot of people from the Scifi Guys at ToughSF to Scott Lowther who made a few models of the Space battleship have done massive deep dives on it.

 

[World B4]

Where are the shock absorbers?

 

[TheKutKu]

Any leads on the whereabouts of the model?

Let me guess…in a storage unit.

Can we not clean this one with Pine-Sol?

https://twitter.com/x/status/1835825639842095569

View: https://x.com/UnwantedBlog/status/1835825639842095569

 

[Paul Lloyd]

another version of that photo

https://twitter.com/x/status/1835245891537482189

View: https://twitter.com/Amaury_Dufay/status/1835245891537482189

Does anyone knowledgeable want to speculate on the lay out of the ship?

In the nose, are the three black triangles Dynosaur-like re-entry vehicles?
What's the conical gubbins tucked into the tip of the nose - is it a SNAP-II type nuclear reactor (on the end of a telescoping arm, like you see in some Phase 2 space station designs)?
What's up with the fins - are they radiators?
Where's the crew compartment - is it the ring between the nose and the weapons bay? Is it a carousel like in 2001: ASO?
What are those coils at the rear? Are they part of the retracted pusher plate?

 

[martinbayer]

As the son of a librarian, I consider the deliberate destruction of *any* artifacts of human endeavors an atrocity against mankind.

 

[MrTopaz]

Where are the shock absorbers?

The corrugated bit at the left/back end looks suggestive of a bunch of stacked inner tubes. OBB on his blog says this looks like an earlier version of the whole concept. Instead of the gas cannon ejecting a pulse unit through the center of the pusher plate, the fins are rails that would be used to drop the the units behind the plates at an angle. There’s a drawing of an early concept of the ship that uses this mechanism (rather than the system we’re more familiar with) somewhere in the George Dyson book, if memory serves. Not a detailed diagram, just a notional doodle, I think. I wonder if there was a time where they thought they could get away with a shock absorption system built entirely around pneumatic tubes stacked like tires. It’s been a while since I read the book, so I don’t remember if that’s covered in it, but that’s my guess as to where the shock absorbers can be found.

 

[martinbayer]

Did anybody ever even try to do just a purely mechanical quantitative evaluation of what that jackhammer on ultra steroids mode of propulsion would do to any humans unfortunate enough to be along for the ride?

 

[Scott Kenny]

Did anybody ever even try to do just a purely mechanical quantitative evaluation of what that jackhammer on ultra steroids mode of propulsion would do to any humans unfortunate enough to be along for the ride?

They said that with the long stroke of the shock absorbers, the total effect was 3 gees pretty constantly, with a ~60hz thrum you'd feel in your bones not so much as "hear"

 

[martinbayer]

Well, I guess there's people who would actually pay for something like that on some so-called "amusement" rides, though being subjected to such an environment 24/7 might change their minds...

 

[Atomic Coyote]

With a large enough vehicle and/or small enough yields you could dial back the acceleration to a lower level if you so desired. Back in college years ago when we looked at modelling the accelerations on an Orion you could get a decent but crude approximation with a spring+damper system between two masses (vehicle and pusher place). As a recall the acceleration plot looked roughly sinusoidal, with some larger transients at startup.

I doubt you'd want to be up walking around while acceleration was varying, but sitting on a couch while acceleration varies 0.5g-1.5g for some minutes doesn't sound like a terrible price to pay to get to one of the outer planets.

 

[Green Ninja Pro]

You slightlt wrong there boss.

Both those projects Originally felled under the Projects Casaba Howitzer.

Which had to do with ALL the weaponize versions of Project Orion pulse modules.

The Nuclear shape charge beam of doom?

Casaba Howitzer

Nuclear EFP? The Shotgun?

Same.

This was the Project, which has both budget docs and personal statements, which made those.

Even the 1980s SDI refers to theses weapons, specifically the beam one, as Casaba Howitzers

And it very much existed.

A whole lot of people from the Scifi Guys at ToughSF to Scott Lowther who made a few models of the Space battleship have done massive deep dives on it.

To further expand on this, my understanding is the fragmenting plate of the Casaba could be scored to the depth (thinness) needed to function as the plate in the Orion-style directed energy Howitzers, allowing a device to easily function as both. They are fundementally separate concepts, but so similar they combine very well, so it just became Casaba-Howitzer.

 

[MrTopaz]

I know the proposed long duration missions didn’t intend to be under thrust the whole time. Atomic Rockets has some illustrations showing the ship tumbling end over end to give some amount of spin gravity. As much as the Orion promised a nearly miraculous improvement over the other propulsion schemes of the time, it wasn’t so powerful that there wouldn’t be a lot of time either in zero-g or under some sort of spin. And although those are for the long duration missions (out to Mars and beyond), AFAIK the proposed Orion Air Force Space Fleet was going to be operating in cislunar space, and would probably be on ballistic flight paths for most of the time, too. Accelerating at even 1/2g for any extended period of time in between the Earth and the Moon would be like putting on ice skates, stepping out onto a rink, and strapping a medium size rocket to your back. Sure, it’ll move you, but in those comparatively confined spaces, that much thrust for too long is just gonna blast you clear across the ice and out of the rink entirely. The great power of the Orion would instead allow you to make nearly any course change at any time.

… I think.

 

[publiusr]

I wonder if there was a time where they thought they could get away with a shock absorption system built entirely around pneumatic tubes stacked like tires.

That might just be a skirt…my guess is that the far side of the model had deeper exposed areas that would show shocks, pulse unit storage…just a guess mind you.

The best use of the craft would be asteroid mitigation/mining.

Build up a lot of speed with no crew—a Falcon Heavy with Dragon atop the ISS de orbit type service module as a fast taxi.

Spare pulse units used for deflection

Nuking a huge asteroid could save Earth, lab experiment suggests

Humanity could use a nuclear bomb to deflect a massive, life-threatening asteroid hurtling towards Earth in the future, according to scientists who tested the theory in the laboratory by blasting X-rays at a marble-sized "mock asteroid".

phys.org

Proof-of-concept study uses X-rays to target mock-up asteroids in a vacuum

An X-ray pulse may be able to vaporize the surface of an asteroid and change its trajectory, according to a proof-of-concept paper published in Nature Physics. A laboratory experiment that mimics the deflection of an asteroid model using this technique suggests that this technology could...

phys.org

The pulse units going off could be a way to “ping” unseen asteroids in the dark.

 

[MrTopaz]

That might just be a skirt…my guess is that the far side of the model had deeper exposed areas that would show shocks, pulse unit storage…just a guess mind you.

I think this is correct. I was able to fish my copy of the book out, and my memory was not perfect. Some There are some drawings that look to have air filled tubes running around the bottom right up to what we might consider the hull, but there are others that are more diagram-like (without being full diagrams) which clearly show shock absorber springs, so there may very well have been a point where they were hashing out the design and had the tubes on as a skirt around the main springs.

 

[publiusr]

A combination of shocks and a tube skirt to ease things a bit.

 

[RanulfC]

Spare pulse units used for deflection

Nuking a huge asteroid could save Earth, lab experiment suggests

Humanity could use a nuclear bomb to deflect a massive, life-threatening asteroid hurtling towards Earth in the future, according to scientists who tested the theory in the laboratory by blasting X-rays at a marble-sized "mock asteroid".

phys.org

Proof-of-concept study uses X-rays to target mock-up asteroids in a vacuum

An X-ray pulse may be able to vaporize the surface of an asteroid and change its trajectory, according to a proof-of-concept paper published in Nature Physics. A laboratory experiment that mimics the deflection of an asteroid model using this technique suggests that this technology could...

phys.org

Ah yes, "GABRIEL" for the win. (Aka "Pulsed Plasma Propulsion" {aka Orion drive "technical" name} powered "interceptor" using "pulse units" for asteroid deflection. Only thing missing was a Nuclear Verne Gun for a launching system )

Randy

 

[publiusr]

That's what "manhole" covers are for (thunderwells).

 

[martinbayer]

That's what "manhole" covers are for (thunderwells).

The Out-of-Towners (1970 film) - Wikipedia

en.wikipedia.org