Indian Private Defence Sector

[Ayan Barat]

In coming months or an year you'll see multiple Indian start-ups pop-up with "jet engines".

These are definitely jet engines but there are some caveats, these are small RC hobby engines

And are extremely simple to make as you've just 10-15 major assemblies and with rise of CNC machining services in India you can get everything in a day or two. These are the typical parts, that's it...

You can even find TDPs for older designs on all the different RC plane hobbyist forums and sub-reddits. And if nothing else, you always have AliExpress.

On paper this may sound very encouraging; a small firm is making an small engine, then they'll absorb the technology, scale it up, ultimately have an afterburning low-bypass engine...but for almost 95% of such, that's never going to happen. Because that's how most Indian tech firms work.

These may have some limited applications in niché loitering munitions but other than that they don't have much in defence. In missiles, comparatively higher quality engines are used despite being single use. You also have the fuel; missiles generally tend to use a higher energy and more importantly, insensitive long term storage capable fuel compared to Kerosene.

So next time you hear some news, don't get too excited. Except for just one or two guys like Prateek Dhawan, all these are pretty much the jet engine version of AliExpress drone/UAV boom that we're seeing.

incase anyone finds the source of this statement, do post it here

Hehe...even Rajnath Singh himself won't be able find the source; it's just Indian defence reporting at its best.

The actual statement was from the new DefSec Rajesh Kumar Singh.

View: https://x.com/ANI/status/1876642394155962672?s=19
Listen from 1:40

 

[Anants]

In coming months or an year you'll see multiple Indian start-ups pop-up with "jet engines".

These are definitely jet engines but there are some caveats, these are small RC hobby engines
View attachment 21234
And are extremely simple to make as you've just 10-15 major assemblies and with rise of CNC machining services in India you can get everything in a day or two. These are the typical parts, that's it...
View attachment 21235
You can even find TDPs for older designs on all the different RC plane hobbyist forums and sub-reddits. And if nothing else, you always have AliExpress.

On paper this may sound very encouraging; a small firm is making an small engine, then they'll absorb the technology, scale it up, ultimately have an afterburning low-bypass engine...but for almost 95% of such, that's never going to happen. Because that's how most Indian tech firms work.

These may have some limited applications in niché loitering munitions but other than that they don't have much in defence. In missiles, comparatively higher quality engines are used despite being single use. You also have the fuel; missiles generally tend to use a higher energy and more importantly, insensitive long term storage capable fuel compared to Kerosene.

So next time you hear some news, don't get too excited. Except for just one or two guys like Prateek Dhawan, all these are pretty much the jet engine version of AliExpress drone/UAV boom that we're seeing.

Hehe...even Rajnath Singh himself won't be able find the source; it's just Indian defence reporting at its best.

The actual statement was from the new DefSec Rajesh Kumar Singh.

View: https://x.com/ANI/status/1876642394155962672?s=19
Listen from 1:40

Ayan can these small turbine be combined with small dynamo to replace batteries in 50 to 100 kg + mtow drones ?

 

[ezsasa]

Hehe...even Rajnath Singh himself won't be able find the source; it's just Indian defence reporting at its best.

The actual statement was from the new DefSec Rajesh Kumar Singh.

View: https://x.com/ANI/status/1876642394155962672?s=19
Listen from 1:40

this one is fine i suppose, it will take a few more cycles for this to be sorted. arriving at consensus on prioritisation of historical backlogs while having to deal with current scenarios within available resources, is creating this mess.

 

[Ayan Barat]

Ayan can these small turbine be combined with small dynamo to replace batteries in 50 to 100 kg + mtow drones ?

Yup, but must consider two factors:

• Normally it's something like [turboshaft > gear > propeller] where energy is not getting converted though there'll be a slight loss in the gearbox. But now it'll be [turboshaft > dynamo > motors > propellers]; so the question is how efficient would this mechanical to electrical to mechanical conversion would be? If it something like 90-95% then it's all fine because that's pretty much the case of gearboxes, but if lower than that then...

• The other is overall efficiency; thermal and fuel consumption especially. Proper, full sized turboshaft engine generally have better efficiency than these smaller engines so they'll consume less fuel. This translates to the overall weight of a "system" capable of flying for a specific time. So you'll have to compare all three
[Fuel worth 1hr + turboshaft] Vs [Fuel worth 1hr + one dynamo + atleast two BLDC motor + turboshaft] Vs [battery worth 1hr + atleast two BLDC motors]

For full sized applications like say a quadcopter-bike capable of carrying two passengers this is a very lucrative propulsion system as you can use Honeywell's turboshaft to generate power and then use simple wires to transfer it to eight motors.
But for smaller roles I don't think there's much application. Because you also have things like high powered Wankel engines which come somewhere in between turboshaft and motor in terms of fuel consumption and power output.

 

[Anants]

Yup, but must consider two factors:

• Normally it's something like [turboshaft > gear > propeller] where energy is not getting converted though there'll be a slight loss in the gearbox. But now it'll be [turboshaft > dynamo > motors > propellers]; so the question is how efficient would this mechanical to electrical to mechanical conversion would be? If it something like 90-95% then it's all fine because that's pretty much the case of gearboxes, but if lower than that then...

I am not aware of that efficiency comparison studies. But as you said they may not be good for small applications. I dont have great Mechanical knowledge. Just an enthu. Here is a patent I found:
https://patents.google.com/patent/EP3004564A1/en

• The other is overall efficiency; thermal and fuel consumption especially. Proper, full sized turboshaft engine generally have better efficiency than these smaller engines so they'll consume less fuel. This translates to the overall weight of a "system" capable of flying for a specific time. So you'll have to compare all three
[Fuel worth 1hr + turboshaft] Vs [Fuel worth 1hr + one dynamo + atleast two BLDC motor + turboshaft] Vs [battery worth 1hr + atleast two BLDC motors]

For full sized applications like say a quadcopter-bike capable of carrying two passengers this is a very lucrative propulsion system as you can use Honeywell's turboshaft to generate power and then use simple wires to transfer it to eight motors.
But for smaller roles I don't think there's much application. Because you also have things like high powered Wankel engines which come somewhere in between turboshaft and motor in terms of fuel consumption and power output.

Thanks Ayan for lucid explanation. Actually I was also musing that if unmanned Sub Mi 32 type of helicopter could be built with Rotors powered by (Kaveri kind of Turbine + Dynamo ) driven large BLDC electric motors. These type of helicopters would be immensely useful for Infra building and Indian construction can eschew S-64 skycranes.

 

[hollowdonuts13]

Drone dropped munition (guided?) from Zues Numerix

 

[Ayan Barat]

View attachment 21294
Drone dropped munition (guided?) from Zues Numerix

Nope, observe the rear fins...there're no movable surface to steer it. It's a simple unguided bomb with only difference being that there's a laser proximity sensor behind that clear plastic dome. It's used for air-burst mode.

Thanks Ayan for lucid explanation

Ayyyee Bhai...no need for all these formalities. I love yapping and you give me a topic to do so; that's it

I am not aware of that efficiency comparison studies.

Larger engines often operate at higher pressures and temperatures, improving thermodynamic efficiency. Also the ratio of surface area to volume decreases with size, reducing relative heat losses. And lastly frictional losses in bearings also scale more favorably in larger engines.

But instead of all these heebie-jeebies we can get a rough idea of it by just taking a look at some turboshafts
•PBS TS100; 60kg producing 240hp - 0.4kg/(hp⋅h)
• PW200; 110kg producing 560hp - 0.25kg/(hp⋅h)
• T700; 250kg producing 2,400hp - 0.2kg/(hp⋅h)
• T408; 500kg producing 7,500hp - 0.18kg/(hp⋅h)
Noticed how as the engine's getting bigger, the more fuel efficient it's becoming. Like we can say that be it 500hp or 7,500hp the fuel consumption is more or less just 0.2kg for each hp for every hour.
Now RC engines
• SPT15-RX; 5kg producing 20hp - 1.32kg/(hp·h)
• Wren Turboshaft; 1.7kg producing 7hp - 9.8kg/(hp·h)

So this is one big issue with any kind of turbine engines and these miniatures ones are just the extreme low. Even in big F-35 and Typhoon type engines, you'd notice this same thing

Actually I was also musing that if unmanned Sub Mi 32 type of helicopter could be built with Rotors powered by (Kaveri kind of Turbine + Dynamo ) driven large BLDC electric motors. These type of helicopters would be immensely useful for Infra building and Indian construction can eschew S-64 skycranes

So now the problem would be bit different.
• you need high power, small turboshaft engines generating electricity - check, we already have engines generating 1MW of power.
• you need high efficiency BLDC motor to convert this back to mechanical energy - and now we start to run into problem. Up to a certain limit we've insanely powerful BLDC or even AFM motors but even they won't be sufficient for these kinds of applications. Even the industry leading AFM motors are somewhere around 200kW of continuous power. For comparison, just to match the power of HAL Dhruv (2x800kW) you'll need 8 such motors.

With time we'll definitely have even MW class motors but as of now light applications like personal quadcopter, light plane, helicopters are the only feasible application.