You completely overlooked the 1910 Coanda plane, using a 4 cylinder engine to drive a fan, with fuel injected and ignited aft of the fan. While it is not clear whether the plane actually flew, it did lead Henri Coanda to note and explore the tendency of the flame to cling to the sides of the fuselage. Now we are well aware of the Coanda effect.

Frank Whittle initially thought of a piston engine to power the compressor in the 20s, but realised it wasn't necessary - a man way ahead.

Adding a pair of v10 engines to a turbofan sounds like a maintenance nightmare.

The all first motorjet engine was built by Henri Coanda in 1910: this engine was installed in a monoplane aircraft and tested from Coanda himself: it works well but Coanda was surprised from the power and the plane did crash during take off.Coanda was not seriously injured but did stop the experiences…Coanda had the help from the Gustave Eiffel and the mathematician Henri Painleve…

so in other words - some of the jets' plusses and all of the piston engine's negatives. Super expensive super complicated and only marginally better in some scenarios. Deadend.

I think it's funny how people drone on about complexity. The piston engine has soldiered on faithfully in so many apps and for 100 yrs in aircraft. Its numerical parts complexity is now just a given. They can all be made very well and not have to run at their ragged metallurgical edge to get the thermal efficiency; as does a turbine running almost at critical mass and can produce no meaningful power outside of that narrow parameter. On a more red neck note who would NOT want to fly in a Learjet that sounds like two Mclaren F1's in a dead heat either side of your cabin. Pod racers eat your heart out.

It’s rare that I see an aviation video with something I’ve never heard of and none of my books have referenced but today you rolled a Nat20.

It's worth also noting the Campini had a turbojet design that used a water cooled turbine. So did the Germans (to overcome alloy problems)

Very interesting, thank you. The various compound engines in the 40s are really fascinating. But when you look at so much complexity for 12% gain there are many other options.

I've been waiting for a video on the VRDK and motorjets in general. I believe if used a little earlier in the war and with more optimization, the tech would have had a nice 3-5yr period of being the best powerplant.

Rolls Royce’s patent of 1995 has long since expired. If anyone thought there was any merit in the engine they would have done something about it by now. I won’t hold my breath.

This channel absolutely rocks. Fact dense but lightly delivered.

This sounds like an interesting engine option to use in a fictional, dieselpunk-themed story setting while also reserving the early turbojet engines as something being experimented on in the background of the said story setting. Said early turbojet research could also be part of a story plot device alongside WW2 research projects like radar, radios, cryptography and early computers, rocketry, etc.

this time flight uploads before i go to work. another good day in the books. but on another note something makes me think these would be deafening.. im getting thunderscreech vibes *edit* 12.5% increase in efficiency 🔥🔥

When I was a kid I read a book on building flying model planes (wires only - decades before RC was common.) One design was a model F-86 with a similar set-up turning an internal ducted fan, but without the fire, of course. Woulda made balsa wood planes - interesting.

Imagine a compound cycle engine where the shaft for the compressor and turbine was also the eccentric shaft for a rotary engine sandwiched in between them

Great video man! Love this format with the voiceover and the various clips and pictures in the background!

Many thanks Flight Dojo, I was looking at Wulf II stepped piston engine last night. It's a delight to see another curious and unconventional engine.

you omited the Coanda 1910 aircraft. It was powered by a motorjet engine too.

Congratulations on the growth of your channel, I can see how interesting it is. Subscribed!

Try a small, compact, 3-rotor Wankel engine, mated directly (no gearbox) behind a 3-5 stage fan setup. Since a rotary engine runs best at about 5k RPM, you can mate it to fan, about 1.1m in diameter, which at 5k RPM would result in tip speeds, just below the speed of sound. Use cooling fins and air inlet in the duct for the engine. Route the fuel and electrical control lines through the struts. Use a jack-screw-mounted bulb in the exhaust nozzle to control exhaust airflow. If you can generate about 1000 lbs of thrust with such a setup, you could power a light GA plane with it.

Fascinating video...thanks..

Always love videos abou italian engines, theres way too little of them out there even though the italians were crazy as well.

First time I've heard of this engine layout. Thanks.

There are some new exciting developments being researched in rotary engines like the Wankel, and despite being a little less fuel efficient than pistons in their current state, rotaries are much smaller, much less complex. much lighter, and operate at much higher rpms... sounds like a better match for a Motorjet to me! Thanks for the excellent video Flight Dojo!

Excellent work.

Excellent channel, excellent video!

This looks like one of those times when you have established tech (piston engines) and new advanced tech (jet turbine engines) and there were a few engineers that understood one well and one not so well, and at that point, it was just natural for them to ask "What if?" and experiment. Each engine type has its pros and cons, and its own use and purpose. I call it scientific due diligence is seeing if it was possible to combine the strong points of each type into a single unit. Today, if you look hard enough on KZfaq, you will find the occasional garage guy that took a turbo charger off a car and made a crude but functional jet engine out of it. I think this was a necessary phase of aviation technology we needed to look at, and a part of what makes aviation history so damn cool.

1:27 didn't (Romanian) Henri Coandă try something like this in a plane in 1910?

Another great video

Love your content as always. Just a note on the Russians late start into Jet/Rocket plane development. They did in fact fly the Bereznyak-Isayev BI-1 rocket powered interceptor in May of 42 with some success.

I was searching for this information as an aviation nerd and didn't find anything so thank you very much.

Well done! And thanks!

10% increase in fuel efficiency is a lot, but i wonder what practical applications this might have for hybrid/electric drives. Electric motors might need less gearing and with many short distance aircraft there might be a sweetspot in between a larger battery and the wight of an electrically driven motorjet to boost range? Kind of like an afterburner for electric aricraft, which would optimally use regenerative fuels or at least fill the gap towards heavier and mid ranged aircraft with better efficiencies? Great video, my jaw dropped when i saw the inline ice which even had enough thrust on its own to power the plane. It's a logic step to use the excess heat but the idea of basically putting an entire engine inside another is really amazing

the exhausts on the spitfire were angled rearwards to get some measure of thrust from the exhaust

Nice one - I had never heard of a motor jet!!

Ive always loved the Italian WW2 and post war planes, beautiful lines

Thanks for showing me this aircraft flay that’s the only early jet I’ve never seen a video of

Thanks for this video, there isn't much out there about motorjets. I found them interesting because even today, with modern materials, temperature at the turbine blades is one of the biggest limiting factors in jet performance. Unfortunately, the tradeoffs don't appear to be worth it, and afterburners end up being a better solution for aircraft that need to go that fast. Maybe something will change, between a new interest in supersonic transportation and better battery technology, it might be possible.

goated with the sauce, great video

We built a compound cycle engine as an example and as a theoretical possible propulsion system for what is now known as the tomahawk cruise missile it was a V8 of about 250 CC's per cylinder running on compressed air produced over 1,000 horsepower! What made this particular compound cycle engine very interesting was a pair of clutches so you could use the turbine power to draw in more air and create more thrust as a conventional turbo shaft engine operates or with the flip of a switch you could add the turbines output to the crankshaft and make insane torque at the crankshaft. I believe it was an old German design from when they were having trouble creating a combuster section with materials of the day and lacking knowledge of modern engineering to create an air cushion between the flame and the metal so that the combustors did not melt through in a matter of seconds. All this contained in a 20-in diameter about 22 in Long it was actually very light, crazy powerful and produced a lot of thrust it was very efficient Considering it had all the modern engineering and materials made thrown at it. I don't know whatever happened to the test engine but it ran for 24 hours a number of times at Garrett Turbine Signal oil now Honeywell Phoenix Arizona.

How have I never come across this concept before... So thoroughly forgotten

I honestly never knew about that version of the Ohka. The various Japanese suicide craft have always been of interest to me to the point where one of my cats is named Kaiten, yet I never heard of that version.

Excellent.

I agree. Ludicrous and cool!

I'm new to this channel but I am definitely going to subscribe

My first visit to the Oshkosh convention was in 1974 and I recall a prototype on display that year or soon after of a one-half size F80 that used an automotive V8 driving an internal fan through a gearbox. I haven't seen or heard of it since then, and it wasn't ready to fly at that time, so I have no idea if it was successful. I suspect that that propulsion design would be less effective on a sport plane than a propeller would be, but the point of it was a jet-powered design without the high cost of a turbine power plant. It interested me a lot because it looked just like the fighter it replicated, only smaller.

You got my subscription with the title

The most practical combustion engine for the Motorjet might be the Wankel! Why?: small size, high rpm and excess burnt oil simply provide extra power to the jet engine stage! Great video!!

The Napier Nomad was also a very cool engine built on this principle.

From what I know about German engineers, and their love of insanely, needlessly complex and expensive overengineering of simple machines, I'd bet the German engineers watching this video experienced a markedly higher heart rate, increased respiration, and a far higher degree of interest when they saw this video.

Thank you

Interesting!

Just found the channel today✌

in the 60's i recall pop science magazines doing storys about putting big Buick engines in Sabre jets on a guy hobby basis.cold jets i think they were called.

I remember reading, as a kid, that during WW2, the Russians had developed an aircraft that employed a piston engine & propeller, and a ram-jet. It reached ~350 mph on piston power, then the ram-jet would kick in.

Yup, ducted fan with afterburner is exactly the thing that came to mind. That is, if there's no turbine, isn't that like an afterburner, except that ignition in the jet's combustion chamber wasn't from an upstream turbojet. Or, am I totally confused.

Thanx, I've learnt sth new. Regards.🤓🛩️

What about the exhaust recovery turbine used on Boeing B-50? I do not know if that’s a motorjet but it added thrust.

I bought one of these engines on the war surplus market and dropped it in my old Buick and it worked okay.

I think its so cool that i knew the name Caproni before watching this video but never having known much about airplane history. I watched an animated film by studio Ghibli that features Caproni as a person of admiration for the main protagonist, a Japanese boy growing up and then working as an aerospace engineer in japan, before ww2. He meets Caproni in his dreams and they talk about wanting to build beautiful aircraft. I dont know how historically accurate Caproni or even the whole era is represented, but it does follow the life of the eventual designer of the zero fighter. Its called The Wind Rises, if your interested. Porco Rosso is another film by Ghibli, set in a fantasy world full of custom bi-planes and skypirates. Iv always wondered how flight would develop in a slower or different environment than history has already proven. Maybe we would see interesting designs like this developed more and become more common place as a form of personal transport completely reshaping the world as we know it. Thanks for this tidy video essay. I really enjoyed learning about this engine!

I have always wanted to build an aircraft for GA that uses a piston engine to power a ducted fan but it will have many stages to the fan each spinning faster.

perhaps the Liquid Piston X3 mini engine could perform better at this task, being far more power dense while having the efficiency bonuses of internal combustion. they had a demonstration aircraft proving hybrid electric operation, with in flight starting and stopping, so perhaps an "Electro-Turbo-Motor-Jet" would be possible ahahaha

I think that this idea still has some validity. With modern piston engines and compressors you could create something that is both efficient at low speeds, and yet possesses turbojet performance for brief periods. All at a relatively low cost.

@Flight Dojo >>> 👍👍

Thank you for the info on the Ohka "motorjet" version. I have seen a Smithsonian photo of their "motorjet" Ohka 22 (the Japanese Navy Air Research Bureau designation - the plain rocket version was Ohka 11) which designates the engine as a "Campani jet" engine. The Smithsonian photo states that their Ohka 22 was "recovered in Japan in 1945 -- I have seen a photo of an Ohka-22 sitting on an assembly trestle in a factory in Japan with piles of Ohka parts and partially assembled Ohka aircraft in the background -- this may (or may not) be the same motorjet Ohka. I'm interested in the Ohka because I have a photo taken of my father and his high school friend standing in front of an Ohka at Yontan airfield on Okinawa. The photo is framed to show his tent in the background. The photo showing my dad includes the Ohka with Identification number I-18. There are also photos around the Internet with good images showing the numbers I-10 and I-13. I was in contact with a correspondent who sent me a copy of two photos, one of his father helping to move Ohka I-10 along a dirt track on a low dolly and another of his father standing next to the rocket engine of I-10 with a date on the photo of 4 April, 1945. This correspondent says that he visited an aviation history museum in Chino, California, to see an Ohka that they have (had??) on display and a curation expert at the museum told him that the invading US troops found five Ohkas, fueled and armed, in a cave on Okinawa and they were removed to an open area at Yontan so that they could safely be disarmed. There are photos of I-18 with its external nose removed while the warhead is being removed. There are also photos showing the solid rocket fuel tubes being removed from an Ohka (this aircraft is not identified but the background surroundings seem to indicate that it is likely also I-18). I do not have any information about any other Ohkas that were captured on Okinawa.

Hmm, this sounds like something of a fun project to try out.

So fascinating, amazing channel, I'm subscribing. Are you still going to buildt a ww1 plane when you reach 100k?

Reminds me of the F 35 with the fan running off a shaft...interesting!

reminds me of that weird prop-jet hybrid in the game IL-2 1946.

Why was there a red image of Ba’al above the test tunnel in the first few couple of scenes?

Interresting that could be implemented in VTOL/STOL configuration. Maybe the F-35 B have that aplication to its wing lifting jets?

Napier Nomad next then please!

Interesting. didn't the Junkers Jumo 004 turbojet used in the Me-262 fighter use a 2 cycle piston engine to start their compression cycle before transitioning to a 'pure' turbojet?

I was a professional pilot for 38 years and never heard of a motorjet? Thanks for letting me know.

If the MTU concept adds efficiency at the cost of weight, it should work on a land-based turbine used to drive a generator. Those utility guys are really, really interested in efficiency. Today they use the output of a turbojet to boil water to make steam to drive a steam turbine, but the steam turbine is taking energy out on the low-temperature side of the cycle, which is less efficient. The MTU concept, if I understand properly, is proposing to take some energy out of the fuel on the high-temperature side of the turbojet cycle, by raising the initial temperature. That improves the Carnot efficiency!

Gille St Hillaire designed a positive displacement motor called the Quasi Turbine. It is 1/5 the size and weight of a piston engine. The engine is empty in the centre and could house a transmission or generator. Multiple units can be ganged together like Wankle. Rotating eliminated vibration and this airplanes could be lighter again

You mite like to look at the Napier Nomad for a presentation, that would definitely add to this presentation

Got here so fast it wasn't loaded

Modern materials science is progressing at breakneck pace, so it's very possible internal combustion engines will become light enough for the combined cycle engine to become practical.

He S 50 was a Motorjet developed at Heinkel by Wunibald Kamm, with inherent better features than the Caproni, that actually was an afterburner reinforced version of Stipa duct fuselage. However, at Heinkel failed in obtaining enough cooling for the 2-Stroke engine, and never reached production. Gesund +

Surprised Harry Ricardo didn’t get more of a mention with the crecy

Almost reminds me of the ThunderScreech

iza gooda looking plane!

Ich finde den Lippenmotor genial.

The air turbo rocket is the turbine version of this concept: a small turbine powered a large high bypass compressor, with most of the massflow going outside of the turbine. The majority of the air of combusted behind the turbine, resulting in high thrust without much thermal stress on the turbine. Only good for high speed aircraft, really

Rolls-Royce began working on a sleeve valve two stroke “sprint” engine aka Crecy. It was all about power at the expense of fuel consumption. Once it was running they realised it could be a great compressor stage for a jet engine. Ultimately, the turbojet was easier to develop so the Crecy was cancelled.

It's pretty neat what Italy did with the "thermo jet", they even tried making fighters and bombers using the concept but the armistice came before any could be produced, though the Caproni campini ca.183 bis was supposedly quite fare along in construction.

There is a mistake at 9:27. There is no turbine in the high pressure section. What you called the turbine is in fact the *radial* compressor section.

0:04 A young Grampa Munster.

A turbocharged multi-rotor engine sounds like it'd be perfect in this sort of application. Better packaging, power to weight and reduced complexity vs piston engines.

In the RC Airplane world we use EDFs Electric Ducted Fan in a wide variety of scale airplane models

I suggest you to study also Henri Coanda . Best regards

If we had 2x atmosphere on earth this would be very practical.

I don't know the aero terminology but would base bleeding the wings help any?

The Napier Nomad of the late 1940's / early 1950's was a brillient implimentaion of a turbocompound engne that at the time offered record breaking fuel efficiency at the expence of horrendouse complexity en.wikipedia.org/wiki/Napier_Nomad. I came accross some drawings when I was an apprentice and the Nomad was much more advanced than the engines we were producing for the HS125 loco's. Unfortunately cheap oil and simple turbojets killed it stone dead. The Nomad was reall a gas turbine using a 2 stroke diesel engine as the combustion chamber with the net result of massive overall compression ratios. Power was taken from both the turbine and the engine via a compley hydraulic friction drive variable gearbox which overcame the matching problems described in the RR patent. Takeoff power could be supplimented with afterburning and water-methonal injection, it was a true beast.

I knew about this engine, or thought I did anyway. I'm sure I remember reading that the Italian's had created an engine that provided thrust just from the exhaust of a piston engine. Either article I read was wrong, I misunderstood, or there are 2 similar types of engine.

i would really like a video about the soviet Bi-1

I think rotaries might be the potentially best engine pairing for a motorjet.

Seems like a rotory engine would be a better option than a piston engine for this kind of layout. They are much smaller, lighter and simpler than a piston engine and they spin at a much higher rpm which I have to think would be better than the slower speed a piston engine needs to run at. They can also put out a lot of power when designed and built well. And are stackable so if you want a larger stack you just need a few longer tie rods and crankshaft and you can essentially bolt two or more engines together. The only downside is that when not built perfectly they can have reliability issues and the engine technology isn't nearly as far developed as piston engines.