# Harrier jet and squash balls **URL:** \ **Category:** Factual Questions\ **Created:** [March 14, 2018, 12:40pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539 "2018-03-14T12:40:32Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![JacobSwan](https://avatars.discourse-cdn.com/v4/letter/j/a6a055/32.png) [@JacobSwan](https://boards.straightdope.com/u/JacobSwan)\ **Post date:** [March 14, 2018, 12:40pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/1 "2018-03-14T12:40:32Z")
An odd memory surfaced in my brain this morning. I vaguely remember some article about government (UK) spending that involved the Harrier jumpjet and one of its service items. There was some bush that needed to be replaced on a regular basis and the suppliers charged several thousand pounds each. But an investigation had revealed that the bush in question was literally a squash ball. Not a super military grade piece of rubber the same size as a squash ball, but an actual squash ball that you could buy from a sports shop for pennies. The supplier defended the cost with the usual BS about testing and supply chain authentication. Does this ring any bells for anyone? Google doesn’t help me as there is a strain of squash seeds called harrier! ---
**Author:** ![Tired\_and\_Cranky](https://avatars.discourse-cdn.com/v4/letter/t/a87d85/32.png) [@Tired\_and\_Cranky](https://boards.straightdope.com/u/Tired_and_Cranky)\ **Post date:** [March 14, 2018, 1:45pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/2 "2018-03-14T13:45:58Z")
I don’t know anything about the story or its veracity but I suspect the term for the part you are looking for is “bushing” rather than “bush.” Sorry I can’t be more help. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 14, 2018, 2:22pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/3 "2018-03-14T14:22:25Z")
Or possibly “bearing”. I’m pretty sure that a bushing has a hole through it, to fit on a shaft. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 14, 2018, 2:26pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/4 "2018-03-14T14:26:40Z")
I wouldn’t have thought a bushing or bearing would be made of rubber - those things are normally made of harder materials like metal or ceramic. Maybe a boot or a grommet, assuming the story has any sort of truth to it. ---
**Author:** ![busterpickle](https://avatars.discourse-cdn.com/v4/letter/b/258eb7/32.png) [@busterpickle](https://boards.straightdope.com/u/busterpickle)\ **Post date:** [March 14, 2018, 2:42pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/5 "2018-03-14T14:42:31Z")
Highly unlikely as parts for aircraft are tracked down to the smallest component, like tiny screws, washers, etc. Could a squash ball be made of a similar/same grade elastomer and be of the same shape as a bushing in an aircraft? Sure, but, is it actually a squash ball? No. Would the coast of making that bushing be the same as a squash ball? Probably a little more as the production runs would be smaller, but then, on top of that cost you have QA, certification, testing, assumed liability, etc. So, that’s where the high cost for aircraft parts comes from I believe. But, there are plenty of aviation enthusiasts who can correct us. ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [March 14, 2018, 2:46pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/6 "2018-03-14T14:46:10Z")
I agree that “bush” is unclear in that context, that “bushing” may be the word you are trying for, and that [neither](https://www.tstar.com/blog/bearing-nomenclature-101-when-to-choose-bearings-vs.-bushings) really work in that context, as a bushing has a hole through it and bearings tend to have a hole through them, too. I will say some bushings and bearings may have plastic parts rather than metal and grease. Plastic is self-lubricating and slides rather than locking up like steel on steel, which is why those need grease or oil. However, I am still puzzled how a squash ball could serve in that capacity. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [March 14, 2018, 2:58pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/7 "2018-03-14T14:58:30Z")
> [@electronbee](#): > > Would the coast of making that bushing be the same as a squash ball? Probably a little more as the production runs would be smaller, but then, on top of that cost you have QA, certification, testing, assumed liability, etc. So, that’s where the high cost for aircraft parts comes from I believe. In the U.S., aircraft parts have to be certified. I remember in the '70s my dad told me about the starter motor on (IIRC) Beechcraft Bonanzas. He said the starter was the same one used in Buicks. But where the Buick starter cost $50 (or whatever), the starter for the airplane cost $300 (or whatever – this was in the '70s). The difference was that the airplane starter had a little plaque on it saying it was certified for aviation use. Certification and testing are indeed costly. An airplane bolt and a hardware store bolt may be identical in every way. But only the airplane bolt may be used in an airplane because it’s been tested and certified. You’d have no way to know if the identical bolt actually does comply. Would you bet your life on it? (And there have been crashes caused by counterfeit bolts that do not meet specifications.) I agree that it’s unlikely that actual squash balls are used. I haven’t heard the story, but I suspect that the things are ‘identical’ to squash balls only they’ve been tested and certified. ---
**Author:** ![DesertDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/desertdog/32/11503_2.png) [@DesertDog](https://boards.straightdope.com/u/DesertDog)\ **Post date:** [March 14, 2018, 4:02pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/8 "2018-03-14T16:02:34Z")
> [@Mangetout](#): > > I wouldn’t have thought a bushing or bearing would be made of rubber Bearings, yeah, but [bushings?](http://www.midatlanticrubber.com/industrial-products/rubber-bushings) OTOH it is hard to imagine a holeless bushing, like a squash ball would be. ---
**Author:** ![TruCelt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/trucelt/32/523_2.png) [@TruCelt](https://boards.straightdope.com/u/TruCelt)\ **Post date:** [March 14, 2018, 4:11pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/9 "2018-03-14T16:11:09Z")
I recall having to look up what a squash ball looks like when I read the following. Top of page 30. It may have been conflated into the report you heard. WARNING - .PDF [spoiler] This link opens to a .pdf [http://airspot.ru/book/file/980/stealth\_warplanes.pdf[/spoiler]](http://airspot.ru/book/file/980/stealth_warplanes.pdf%5B/spoiler%5D) ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [March 14, 2018, 4:32pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/10 "2018-03-14T16:32:56Z")
> [@Mangetout](#): > > I wouldn’t have thought a bushing or bearing would be made of rubber - those things are normally made of harder materials like metal or ceramic. Maybe a boot or a grommet, assuming the story has any sort of truth to it. Bushings are made from all kinds of materials, [including rubber;](https://www.google.com/search?q=rubber+bushing&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiQ0bq9nuzZAhVFhOAKHQaBDHwQ_AUICygC&biw=1280&bih=893) the choice of material mostly depends on how rigidly you want to connect two components. ---
**Author:** ![ElvisL1ves](https://avatars.discourse-cdn.com/v4/letter/e/5daacb/32.png) [@ElvisL1ves](https://boards.straightdope.com/u/ElvisL1ves)\ **Post date:** [March 14, 2018, 5:19pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/11 "2018-03-14T17:19:37Z")
It’s possible a snubber or bushing, such as in landing gear where it would act as a shock absorber, could be made from \*the same material \*as a squash ball, but a sphere would probably not be a useful shape anywhere on an airplane. Hollow cylinders, yes. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 14, 2018, 5:39pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/12 "2018-03-14T17:39:15Z")
> [@Machine\_Elf](#): > > Bushings are made from all kinds of materials, [including rubber;](https://www.google.com/search?q=rubber+bushing&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiQ0bq9nuzZAhVFhOAKHQaBDHwQ_AUICygC&biw=1280&bih=893) the choice of material mostly depends on how rigidly you want to connect two components. Yeah, I did that search after posting above. I can’t find any kind of bushing that looks like a squash ball though. I did find some rubber boots for ball joints that were sort of ball-like - but if that’s what is being described in this story about military jets, it would still have to be a ball with some holes in it - and just punching a squash ball would probably result in something that fails prematurely. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [March 14, 2018, 5:47pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/13 "2018-03-14T17:47:22Z")
> [@JacobSwan](#): > > The supplier defended the cost with the usual BS about testing and supply chain authentication. Even if this story were true, testing & authentication is definitely _not_ BS. What if one batch of balls is defective in some way? Can the manufacturer track down the problem and tell you exactly which balls were affected by that problem? If not, you’ll have to inspect every single ball you’ve ever bought from that company and installed in your aircraft. Is there any guarantee that every ball you buy from that company, now and in the future, is similar to the ball you originally tested? The company may produce squash balls in different factories, perhaps with slightly different materials, and label them the same. They may change the design in the future and not tell you. They will all work fine as squash balls, but how do you know they all work well enough in your aircraft? Maybe their new and improved rubber becomes brittle when cold, or more elastic than your aircraft design calls for. ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [March 14, 2018, 10:37pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/14 "2018-03-14T22:37:24Z")
Bushing is done with bushes: bushes are made of bushing. [undercarriage bushes](http://www.hanleysmith.co.uk/2016/10/bush-removal-from-boeing-737-undercarriage-components/) ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [March 16, 2018, 1:44pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/15 "2018-03-16T13:44:24Z")
Lol. So you get given some landing gear, and you change one part, a rubber bushing containing as much rubber as a squash ball, and then xray the whole landing gear, and then return it, and the bill is $3000. Its $10 for the part, and $2990 for the xray,expertise, mechanics,handling,security,record keeping. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 16, 2018, 1:55pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/16 "2018-03-16T13:55:38Z")
I’m reminded of the LIGO detectors. They’re the most precise scientific instrument ever built by man, and involve (among other details) large masses hanging from wires. They needed wires that met a very exacting standard of vibrational properties, and discovered that exactly what they needed was already commercially available as piano wire. EDIT: Of course, other components, like the 40 kg flawless single-crystal sapphires, were slightly less commercially available. ---
**Author:** ![Hampshire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hampshire/32/4887_2.png) [@Hampshire](https://boards.straightdope.com/u/Hampshire)\ **Post date:** [March 16, 2018, 3:39pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/17 "2018-03-16T15:39:11Z")
I could see it if the tolerance specs on the part were very, very loose. If it was basically a concave rubber bushing that they could make by cutting a squash ball in half and drilling a hole in it and the drawing called out “butyl rubber no less than 50 durometer no greater than 80”, thickness of .25 +/- .05, etc. etc. again with some very loose tolerances and a squash ball fit the bill and all the parts passed inspection then why not? However, I’d think even something like a rubber bushing on a harrier jet has some extremely tight tolerances that must be adhered to. ---
**Author:** ![mixdenny](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mixdenny/32/2962_2.png) [@mixdenny](https://boards.straightdope.com/u/mixdenny)\ **Post date:** [March 16, 2018, 3:44pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/18 "2018-03-16T15:44:38Z")
> [@TruCelt](#): > > I recall having to look up what a squash ball looks like when I read the following. Top of page 30. It may have been conflated into the report you heard. > > WARNING - .PDF > > [spoiler] > This link opens to a .pdf > > [http://airspot.ru/book/file/980/stealth\_warplanes.pdf[/spoiler]](http://airspot.ru/book/file/980/stealth_warplanes.pdf%5B/spoiler%5D) I’m impressed that you have a 184 page document on how to design a stealth aircraft. Dennis ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [March 16, 2018, 7:04pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/19 "2018-03-16T19:04:14Z")
> [@Johnny\_L.A](#): > > In the U.S., aircraft parts have to be certified. [snip] The difference was that the airplane starter had a little plaque on it saying it was certified for aviation use. Certification and testing are indeed costly. > > An airplane bolt and a hardware store bolt may be identical in every way. But only the airplane bolt may be used in an airplane because it’s been tested and certified. You’d have no way to know if the identical bolt actually does comply. Would you bet your life on it? (And there have been crashes caused by counterfeit bolts that do not meet specifications.) > [@scr4](#): > > Even if this story were true, testing & authentication is definitely _not_ BS. > > What if one batch of balls is defective in some way? Can the manufacturer track down the problem and tell you exactly which balls were affected by that problem? If not, you’ll have to inspect every single ball you’ve ever bought from that company and installed in your aircraft. > [@Melbourne](#): > > Bushing is done with bushes: bushes are made of bushing. > [undercarriage bushes](http://www.hanleysmith.co.uk/2016/10/bush-removal-from-boeing-737-undercarriage-components/) I agree with these. There are different levels of functional requirement and different levels of certification depending on usage (at least in NASA), but supply chain documentation is very thorough. For instance, metal parts a traced back through the manufacturer listing the processes applied (heat treatment, etc) all the way back to the source metal. If something fails and they identify it was a bad batch, they want to be able to source _where_ the problem occurred, and what caused the bad batch, and how it missed quality control. > [@Isilder](#): > > So you get given some landing gear, and you change one part, a rubber bushing containing as much rubber as a squash ball, and then xray the whole landing gear, and then return it, and the bill is $3000. > Its $10 for the part, and $2990 for the xray,expertise, mechanics,handling,security,record keeping. You might x-ray the part or the rubber, or may use some other inspection technique. Some of that may go into verifying the rubber part meets it’s tolerances prior to and after installation, that the proper installation technique was used, that the rubber wasn’t damaged by improper installation. And that doesn’t get into design qualification and certification, which is another big expensive hassle. > [@Hampshire](#): > > I could see it if the tolerance specs on the part were very, very loose. > If it was basically a concave rubber bushing that they could make by cutting a squash ball in half and drilling a hole in it and the drawing called out “butyl rubber no less than 50 durometer no greater than 80”, thickness of .25 +/- .05, etc. etc. again with some very loose tolerances and a squash ball fit the bill and all the parts passed inspection then why not? > However, I’d think even something like a rubber bushing on a harrier jet has some extremely tight tolerances that must be adhered to. Not for an aviation critical part on, say, a landing gear. You wouldn’t grab a random squash ball and cut it in half and punch a hole in it, or even install the whole ball intact. Now on some non-safety critical parts, such as astronaut tools that are not mission critical, I’ve done some cheap off-the-shelf tools with minor mods (Snap-on T-wrench with some shrink tubing and a metal keyring). And using things like Sharpie markers requires getting Sharpie markers from Sharpie with paperwork verifying it meets it’s design standards. This is because of outgassing concerns and chemicals in the environment that the astronauts have to breathe. I have a real hard time with the elements of this story. ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [March 16, 2018, 7:22pm UTC](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539/20 "2018-03-16T19:22:04Z")
> [@Melbourne](#): > > Bushing is done with bushes: bushes are made of bushing. > [undercarriage bushes](http://www.hanleysmith.co.uk/2016/10/bush-removal-from-boeing-737-undercarriage-components/) I have never run across that use of terms. Then I looked and that site is from the UK. Ah, that must be the source of the distinction. In all my experience, the item is a “bushing”. “We need to install a bushing.” [Next page](https://boards.straightdope.com/t/harrier-jet-and-squash-balls/810539.md?page=2)