What are Hypergolic Rocket Fuels? (Other than Explosive, Corrosive, Toxic, Carcinogenic and Orange) 

Hypergolic fuels: Booms, Bangs and Bottles full of Nope since 1935.

“Ignition!” occupies a special place in my library.

As Derek Lowe once wrote in his 'Things I Won't Work With' column, "There aren't many gently sloping paths down to nitrogen gas."

Does anyone else kinda feel like sometimes when Scott says "fly safe" its almost like a threat or ominous advice that a supervillian will give?

ah Aerozine 50, the Arnold Palmer of hypergolics

When the chemical you're using to make your propellant safer is ***hydrofluoric acid***, that's a rocket fuel I'll take with a tall glass of nope!

"Oh no, we spilled some liquid oxygen! What do we do?" "Shut off any ignition sources and leave the area. Just wait it out."

I loved this video. It reminded me of the time way back when I was a kid when I was playing with some friends and we accidentally made a hypergolic mixture. Some other kids had raided a chemical storage building and we had gallon jars of reagent grade acid in just about every basic variety. Quarter of a small test tube filled with nitric acid and other "stuff" went boom. Burned a hole in the ceiling and through one kid's coat giving him the nastiest big green scab. We did a little research and figured out we'd accidentally made rocket fuel, but I had forgot about that until watching the fuming nitric acid in this video. Damn, I had a good childhood.

"Scott Manley, the hypergolucky guy!" (From "happy-go-lucky", in case you've never heard the term before!) Excellent video as always, Scott, thanks!

I've been reading Ignition! myself recently. Thank you for recommending it! It's a fantastic book!

This reminds me of an incident that happened some time back in the 90's when I worked at Rocketdyne in Canoga Park. Two scientists were killed in an explosion when they mixed some chemicals together. I don't know what they were mixing, but the initial story was that they were doing rocket fuel research. Later, the truth came out; they were actually illegally disposing of hazardous chemicals by combustion, and the company used "research" as an excuse to get around environmental laws. This happened at the Santa Suzanna Field Laboratory, which we called "the hill".

I'm a fan of the British Black Arrow's sort-of hypergolic system using the heat (600F) from decomposing H2O2 to auto-ignite the RP-1.

Wrote out a long comment on the Me163 and of course you covered it! What an absolutely insane machine. Used two fuels that when mixed they ignited... and the pilot sat in between the tanks in the wings, and right in front of the primitive, unstable rocket motor. The Me163 had to be refuelled from two separate trucks that had to stay far away from each other to prevent even the fumes from mixing. One drop in the wrong place, any unnoticed spill before the other fuel was loaded, and BOOM. (One fuel type per wing, they couldn't touch before reaching the rocket motor). You had to be a real mad lad to be on the ground crew, and clinically insane to be the pilot.

As a chemist, love these chemistry videos! When I watched that Boeing launch abort test I recognised the gas as NO2, glad you're here to explain how that came about because I was wondering! One small point - be careful how you use the terms "strong acid" and "weak acid" because although HF is very reactive it is not technically a strong acid. Strong acids are defined as acids that completely dissociate in water and HF does not because the bond is stronger and has more covalency due to better orbital overlap. Further to that, the 1% HF you're talking about is described as a dilute acid because a weak acid is defined as an acid that does not fully dissociate in water.

If you have to wear a space suit _on Earth_ the design of your spacecraft may need rethinking.

Using HF to protect the rocket plumbing from acid is like using Sodium Fluoride to protect teeth from acid, just a lot more extreme.

Great explanation, Scott! And thanks to all the commenters who suggested John D. Clark's _Ignition!_ I just bought it for my Kindle, and Asimov's Foreword had me laughing out loud!

In the Army we had to deal with a lance missile that had malfunctioned. It used UDMH and IRFNA. Both were a bitch because they could compromise the filters in a gas mask and then melt your lungs. We had to use full rubber tap suits with self contained breathing systems just to approach the missile. Then we had to render safe the damaged warhead and retrieve the telemetry package. This was probably the most dangerous thing I did.

We already have a "clean" hypergolic oxidizer. The jetpack they used at the Olympics used it as a monopropellant. It's Hydrogen Peroxide, and at a high enough purity (over 80%) it is referred to as High Test Peroxide, or HTP. Very suitable as a rocket fuel oxidizer. Problem is, it's not nice stuff to handle, and it's not long-term stable. The hydrogen peroxide you can buy in the drug store is 3-5% peroxide with the rest being water. Hair-bleach grade peroxide is 10%, and you don't want to spill that on you by accident. Peroxide you find in a chemistry lab supply catalog is commonly available up to 30% concentration, and if you get that on you you'll get a chemical burn. The rocket grade stuff is potent enough to eat the flesh off of your bones quite rapidly. On the bright side, hydrogen peroxide is not stable enough to be poisonous or carcinogenic, and many plants and animals have enzymes specifically to deal with decomposing hydrogen peroxide (so called Peroxidase enzymes). The primary problem with HTP is it's stability, or more correctly it's lack of long-term stability. Hydrogen peroxide at any concentration will spontaneously decompose to water and oxygen gas without the presence of a catalyst, so every vessel that is expected to store hydrogen peroxide has some form of pressure-relief valve or pressure accommodating features in it as a safety measure. Hydrogen peroxide is commonly stored in plastic bottles with the top section having a bellows or accordion shape, specifically so the oxygen that forms when hydrogen peroxide decomposes has somewhere to go without making the bottle explode. Britain used peroxide in many rocket engines with RP-1, and that combination might as well be hypergolic. Sure, it's not RELIABLY "ignites on contact" hypergolic, but if the peroxide is decomposed by running it thru a catalyst bed the resulting reaction products (water vapor and oxygen gas) exit the catalyst bed at a high enough temperature to ignite the RP-1, which will burn using the oxygen liberated from the peroxide, so you still get the end result of ditching the ignition system (unless you count the catalyst bed, however I don't count that because it's in constant operation while the engine is firing). With a similar approach, pretty much any standard non-hypergolic rocket fuel will work with HTP. I believe that combining HTP with one of these new green monopropellants would result in a green bipropellant, however I have no idea if anyone has investigated this. The reason hydrogen peroxide is not used for rocket oxidizer much today is that it has poor specific impulse. With the same fuel, Liquid Oxygen will provide superior specific impulse compared to H2O2 as you don't have to lug around all that water that can't react with the fuel. When a storeable propellant is needed, UDMH/NTO is preferred because it gives superior performance, however I do believe that there have been rocket engines that used the hypergolic combination of a hydrazine-type fuel and H2O2.

Starting the weekend with Scott Manley!

9:32 - and that's how Scott Manley told North Korea what they were doing wrong...

Thanks again Scott.. I always wondered about fuels and their properties.. Great class.. I even took notes.. carry on, be safe and have fun doing it!

Back in the early 1970's I worked for a watchmaker/jeweler who used fuming nitric acid to clean silver, he would put a little on cotton wool and then wipe the silver with it.He said it spread the silver about,one thing for certain it always gave him sore fingers as he never wore gloves and by the next day was complaining about not being able to work as his fingers were sore. He never learnt I said on many occasions he should wear gloves.

Missed these types of videos from Scott lately. Happy it’s back.

We tend to think of hypergolics as highly reactive fuels which ignite upon contact with highly reactive oxidizers, but then there is chlorine trifluoride which is hypergolic with rocket engines, rocket scientists and rocket launch pads...

The lighting was great and audio better! Content was fantastic as always too :D Top work!

Smelly too, in the case of aniline. Edit: And no love for Britain's RP-1/HTP engines? If you decompose the H2O2, the oxygen and steam are hot enought to be hypergolic with kerosene.

Great as always Scott. I'm just finishing reading Ignition!: An Informal History of Liquid Rocket Propellants and absolutely love it. Fascinating read on the history of rocket fuels.

Your video about propellants inspired me to start reading "Ignition!", and I literally read the chapter you just covered today!

Another great video Scott, always enjoy your content. Hope you have a good weekend!

Thanks for covering red- and white-fuming nitric acid. Long ago, I read references to them, but no one ever explained what they were, and you couldn't find it even in specialty shops! The "fuming" part should have tipped me off.

Thanks for the chemistry lesson Scott!

A lot of Europe is in a place right know where they would need someone from science instead of a politician. Know that I've made my nephews watch these videos of yours and they want to learn so much more. Yours sincerely iamthebeelzebub.

It's a good day when there's a new Scott Manley video!

Fascinating summary Scott, thanks!

That was a fantastic summary. This whole area of chemical engineering is pretty much a mystery to most other engineers. I had heard those propellant terms many times over the years without knowing what they really meant. THANKS!!

One nice thing is that their mach diamonds look beautiful!

Fascinating stuff! Thanks for this interesting summary! 🚀💥💨

I like the word "Hypergolic".

One of the handful of consistent channels where I don't feel less intelligent after watching a video, which is very much appreciated!

Thank you for this very informative video Scott.

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Now this is great stuff. Nobody does rocket science like Scott Manley. Fabulous fuel talk about stuff I really wanted to know. In my job I use strong nitric fuming like this. Never knew about inhibitor system using HF. Golden man! Top drawer!

Thanks, Scott. A very professional and understandable video!

Scott - you’re very close to 300,000,000 views on RU-vid. 🤯 Congratulations!! And thanks again for all the amazing content.... onwards to 1,000,000,000!! Fly safe!

My favourite video from this channel

The most amazing thing about the Hydrazines is that they figured out how to make them at all. as you say, Hydrazine tends to blow up at the drop of a hat. with a fairly high explosive velocity.

Great explanation, as always! Thanks.

I worked around the Titan II when I was in the USAF in the late 1960’s. Those propellant transfer guys didn’t fool around. If you haven’t seen “Command and Control,” the documentary about the time we almost had Armageddon in Arkansas, it is worth the time to watch.

Thanks. After one of your recent videos, I was left wondering about the term hypergolic.

ANY other person or RU-vidr would require 1hour to explain it. Scott does the job in 11minutes with lots of it coming from his memory.

Thanks for another really fascinating video!

Early congrats on 1M subs Scott, it won't be long now. Thanks for all of the great info on our space programs.

Good explanations - thanks!

very nice explanatory video!

Never looks away from the camera toward a prompt screen or says "err" whilst searching for the right word. He knows what he is talking about. Respect.

"The real name for Hydrazine is hard to say, but that's the least of your problems" lol

4:30 space shuttle in present tense - shall we tell him ?

Great job for this information

Don't forget that the British Black Arrow used a quasi-hypergolic mixture of catalyzed hydrogen peroxide and RP-1. Once passed over a catalyst, HTP decomposes into very hot steam (about 800F IIRC) and molecular oxygen, which readily combusts with RP1 and probably other fuels as well. This remains an under-utilized combination. Yes, it is lower performance, but it more than makes up for it by the lack of cryogenic qualities, low toxicity, and high density.

Yess more stuff on hypergolics!!! Starting the weekend the right way!

Classic Intro, GREAT =)

An alternativ to Aerozine 50, used by Ariane 2-4 is UH25, wich is a mix of 75% UDMH with 25% Hydrazine.

You are amazing Scott I love space because of you bro

You didn't mention the nastiest oxidiser of them all: Chlorine Trifluoride This stuff makes literally anything a hypergolic fuel.

More of the same in the book "Ignition!" It's a fun book.

Hi Scott. Thanks for the great content. Would you do a video on Reaction Engine's recent success in testing their pre-cooler?

When the footage of the dragon capsule escape system test failure came out and people on the news were talking about "clouds of smoke seen for miles" I just remember seeing the footage and saying aloud, "That's not smoke guys; that's nitrogen dioxide." Thanks for the "Ignition" recommendation; I'm so happy it was reprinted.

I'm currently writing a large assignment on hypergolic fuels. This has been such a good help, since getting a grasp of the subject is.. well, rocket science.

HF is not a very strong acid, it just happens to be able to etch glass and is very toxic. It's just a tad stronger than formic acid but nowhere near nitric acid. As you go down the halogen group the acids get stronger, so HF is actually the weakest of them, followed by HCl then HBr and HI. Fun fact as a side note: that part of the safety data sheet could very well also be from some of the nastier essential oils. (Though pretty much all of them are nasty when concentrated)

I'm not a chemistry expert, but I think "nitrogen tetroxide" should be a completely correct name. You can leave out the prefix when it's the "standard" mixture... mononitrogen tetroxide isn't really a thing as far as I can figure, so dinitrogen should be the correct default when you've got four oxygens.

Thank you Scott for this very informative video! I would, however, like to point one thing out: Hydrofluoric acid is not particularly strong, it is only about as strong (or, rather, weak) as citric acid. Despite this, it is dangerous to handle since it can penetrate the human skin. Additionally, it is the only acid able to corrode glass.

Thanks...Scott..!

incredible explanation. thank you

Scott Manley you are the man

Great video, Scott!😍 how about a follow up video about pyrophoric substances?🙌🏼

The knowledge drop is both intense and effortless, must be a Scott Manley video!

Nice, a video on monopropellant should be very interesting too :D

You rock Scott keep it up

Things spontaneously combusting seems to be a theme in rocket science.

Just learned what a methyl group is. Thanks Scott!

Yup. Used to work with MMH/NTO systems. Fun stories!

I misunderstood the title as being what are some hypergolic fuels that aren't like the rest, but still a good video.

Explosive, Corrosive, Toxic, Carcinogenic and Orange... I did not expected this channel to talk about politic. :D

Fantastic video, I wish you could have mentioned the necessity of sticking with hypergolic fuels for relighting rocket engines without fail. For when you absolutely positively need to get off the surface of the moon. That, and the problems with housing solid rocket motors in orbit.

Scott: Make a video on the advantages to remplace hypergolic control thrusters with cryogenic propellants with ignition for RSC and main propulsion, this allows higher isp, is not a nasty stuff and you can use all the fuel you have in what you most need (propulsion or RSC). Why few spacecraft took advantage of that? taking into account how easy is to store cryo fuels on space (in case you have clear enough how heat flow work on space, emission coefficients, reflection, etc)

While watching OLF I thought.. 🤔 Hmm I wanna brush up on my knowledge about hypergolics.. Aaaaand Scott just released exactly this 👍

I sensed this video coming when I saw you discussing this on the Twitter

RFNA was also part of the rocket that blew up on the pad during the event that would be called the Nedelin Disaster/Catastrophe (named after Field Marshal Mitrofan Nedelin).

Hey Scott, love your vids. Have you ever considered hanging up some sound panels to improve your sound quality? You can also diy them with old towels and cover it with a nice space or kerbal print ;o) Just a thought.

2:41 reminded me the "Only the good" episode of Red dwarf, when Rimmer was trying to memorize the name of some compound and then trying to say it.

I took a lotta antihistamines and I’m just trying not to fall into my phone but I can oddly comprehend 90% of everything chemistry he’s sayin

Don't know if you have seen this but it explains rocketry basics so easily, it's a good video. It's rocket science! With professor Chris Bishop

It's scary to see all these flasks of these chemicals so close together.

My Lance Missile systems back in the 80's used UDMH and IRFNA (Inhibited Red Fuming Nitric Acid) bad stuff! Safety suit colorations were very important!

I live in Titusville FL, within view of the VAB on KSC. A neighbor works out there and after a few beers likes to talk about all these chemicals stored out there....makes me wonder. I personally have seen that orange smoke after incidences out there..

Science Friday with Scott Manley!

What a great voice & content! 😉

The german DLR made experiments with a mixture of N2O (laughing gas) and ethylene/ethan. The mixture is not hypergolic by itself, but the laughing gas can be decomposed by a catalyst. The decomposition ist exothermic and the gas is hot enough to ingnite the resulting oxygen/fule mixture. Let's call it indirect hypergolic ... Both laughing gas and an ethylene/ethan mixture are only little harmfull to health and environment.

Rocket chemistry is best consumed while tipsy. Thanks Scott!