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

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

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?

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."

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!

ah Aerozine 50, the Arnold Palmer of hypergolics

"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!

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.

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

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.

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!

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.

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

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

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.

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 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...

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!

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.

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.

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

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

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

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.

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!

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.

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

It's a good day when there's a new Scott Manley 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 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.

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

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.

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

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.

One nice thing is that their mach diamonds look beautiful!

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

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.

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.

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

Thanks for the chemistry lesson Scott!

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

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

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!!

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!

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

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

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

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

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

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 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.

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.

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

Classic Intro, GREAT =)

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

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

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

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

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

Monomethyl hydrazine and Nitrogen Tetroxide... Fun, fun, fun. Working with that stuff on the shuttle program in the early 90's was exciting.

The safety training you receive when working at launch sites will always be funny to me no matter how many times I go through it. "A looks like B and smells like C; get the f*** out of the area.", "D looks like E and smells like F; get the f*** out of the area.", "G looks like H and smells like I; get the f*** out of the area."

You are amazing Scott I love space because of you bro

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).

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

My favourite video from this channel

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

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

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

When you've got to put on a moonsuit that rivals the newest generation of spacesuits just to be around these chemicals, most people generally look for another line of work.

When I'm debating people, I've been told I'm quite hyperbolic. Glad I know what they mean now. I'm very powerful.

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.

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!

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

A shout out for the book Ignition.... a great read on rocket fuel since the early years plus a big dash of humor to make it ‘palatable’, if you like reading how men perused the life of burning, singing, popping and banging, to massive explosions wrecking fume cupboards, labs, rocket engines and test sites or simply nothing at all.

I remember this from the first time, C-Stoff and T-Stoff from the Messerschmidt Me 162.

Last time I was this early, the Dyna-Soar was still being researched

Curious Droid has an interesting video on the Black Arrow rockets that used hydrogen peroxide (HTP) and kerosene. With a distinct lack of nitrogen in the reaction, that seems much safer. It strikes me as a suitable fuel for an aerospike since the HTP can be used to help aid cooling of the spike. Anyway, all useless speculation as current rockets are pretty damn well understood.

Isn't, as the old saying goes: "everything is a hypergolic if the percent oxygen is high enough"

Chinese still have a whole bunch of pre-Long March 5 (which finally switch over to non-hypergolic fuel) rockets that they're constantly using. They're using fun stuff like UDMH as fuel & N2O2 as the oxidizer, and they launch these rocket very close to populated area.

You need a model NCC 1701 Enterprise model on your shelf behind you:)

The trick, William Potter, is not minding that your fuel could go kaboom !!!

Science Friday with Scott Manley!

Its not often you get to say "added a bit of Nitric acid to make it LESS corrosive"

Rocket chemistry is best consumed while tipsy. Thanks Scott!

I miss the whoop sound of the turbo pumps firing up in the Titan II launch vehicles.

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.

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

I'm still waiting to see a clearer explanation of the N2O4 cloud that enveloped the Starliner a few days ago while still in the air. In addition to looking bad my concern is that it may have played a role in the failure of the third parachute. Additionally, when the capsule landed, quite close to the service module, the fumes blew towards the capsule and if they use venting to equalize the capsule pressure so they can open the door then fumes could easily get into the capsule and that would not be good for the crew. Something just didn't look right with the N2O4 cloud as the chutes were deploying.

A corrosive, volatile, carcinogenic and downright dangerous liquid going through a rocket turbopump and combustion chamber at very high speed and pressure and heat. what could POSSIBLY go wrong?!?!

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

The sight of flasks full of hydrazine and its derivatives on the same table as a flask of nitrogen tetroxide... is scary ☠️🤯☠️

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)

Thanks, Scott. A very professional and understandable video!

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..

Thank you for this very informative video Scott.

I've been working the F 16 for 25 plus years and they use H70 as a fuel for our emergency power unit that runs a generator and hydraulic pump just in case our single engine stops working. Never have heard of a "spill" so far. Seems pretty stable as long as it's contained...