Turboprop Cessna 172

Sure, it’s sfc is half that of the avgas burners (supposing we believe that we always operate them at the most efficient spot – which we obviously do…). However it weighs less than a third of a comparable piston engine so between that and higher JetA1 density the problem isnt unsolvable (added benefit – less weight on the nose, smaller arm required for the stab, less effort on the nose gear).

Add to that far smaller frontal area and no cooling drag and one might actually go a bit faster on less power.

Having said that Gnome rotary engines work perfectly, no reason to change.

LeSving wrote:

Is there anything such as SEJ-rating?

Jet means type rating. But something like this is Annex II, I have no idea what you need (depends on national law).

tomjnx wrote:

I don’t know where you have your prices from

It was from Sonex. A long time ago though as a guesstimate (I guess ) . 44250 € is also a lot of money, but no more than a standard 540. There is at least one RV-10 with a TP-100 flying a couple? of years ago, maybe several today. Ahh, I remember Kitplanes had a recent article about the Subsonex. Here is the utube version where they talk a lot about the engine also, they mention US$ 55k for the engine.

I don’t know where you have your prices from, but Desert Aerospace LLC seems to offer the TJ-100 for 44250€. Far from 100k$, and getting cheaper in $ because I’m sure Goldman Sachs will do anything they can to get the € far below dollar parity 8-)

It’s not cheap. The turbojet version, which is a very much simpler machine, costs about US$ 100k or close to it. It’s used in the SubSonex (the same kit manufacturer making the Sonex series and the Onex)

I would guess the turboprop is at least US$ 150k, maybe 200k. Then it has to be installed, so the whole thing will probably cost at least 300k + the C-172 itself.

The SubSonex looks supercool, and anyone can build it. It also requires jet rating though, and I wonder how to do that in EASA land. Is there anything such as SEJ-rating?

Talking of W&B: do I rightly observe the engine (and firewall) have been moved further forward, to make up for the reduced engine weight? Same happened when the Pilatus Porter was upgraded into the Turbo Porter, leaving a curious empty space between cockpit and firewall. If so, that space could neatly serve for extra fuel storage – even with a cork & needle level indicator!

No, but it comes with an optional CAN to RS232 converter, which features cheap Sub-D connectors, which are known to be no good.

More seriously, here’s some more data about the engine. I wonder whether they’re going to increase the tank size, given that their SFC is 0.82 lb/hp/h, i.e. almost double that of a piston engine.

Nice! The noise of a TP is alone worth every penny

Doesn’t the downward-pointing exhaust affect the W&B envelope?

Does the turboprop come with manual fuel pressure adjustment to adjust for ambient air pressure and temperature fluctuations? Because such a thing would come in handy in cruise where no adjustments are needed. And electronic turbine FCUs are vastly known to fail very frequently.