New Piper Seminole powered by DeltaHawk

[toto]

I missed this when it was unveiled at Airventure last month. 

It sounds like Piper is planning to sell brand new Seminoles with DeltaHawk engines, using an STC that Piper owns. 

https://generalaviationnews.com/2025/07/24/piper-unveils-seminole-powered-by-diesel-deltahawk-engine/

This is the more mature 180hp variant, not the more interesting 200 or 200+ variants. But still, getting more of these in the wild in certified aircraft will tell us a lot more about the long term viability of the powerplant. 

https://www.deltahawk.com/engines/

Given all of the painful recent decisions on UL avgas, I’m happier thinking about diesel again …

[Flyler]

It may be worth losing 20hp for some IO-360 pilots as (and I'm just assuming here without reading tech specs) you get that 20hp back pretty quickly at altitude due to the turbo.

My pipedream here is that MOSAIC gets expanded to allow "decertification" of our Mooneys and we can use experimental engines.  The Deltahawk concept looks great to me.

[N201MKTurbo]

If you are willing to give up 20 HP, you could probably detune an IO-360 to run on UL94.

[Hank]

1 hour ago, Flyler said:

It may be worth losing 20hp for some IO-360 pilots as (and I'm just assuming here without reading tech specs) you get that 20hp back pretty quickly at altitude due to the turbo.

My pipedream here is that MOSAIC gets expanded to allow "decertification" of our Mooneys and we can use experimental engines.  The Deltahawk concept looks great to me.

It's a wash for my C. What is the engine weight? 

[toto]

37 minutes ago, Hank said:

It's a wash for my C. What is the engine weight? 

335 pounds, including the starter, turbo and exhaust

 

SpecSheetBack-April2025.pdf

[Hank]

Wow! Just over half the displacement, and almost a third heavier. Not sure I can take an extra 75 lb on the firewall, and they cleverly don't say if the 335 lb weight includes oil and coolant. Lycomung advertises 258 lb dry weight, and 6 quarts of oil is ~9-10 more pounds. 

[Gee Bee Aeroproducts]

Stc and product liability killed the 6 cylinder Rotax 

 

Shame 

[Crawfish]

The 235HP variant seems like an awesome replacement for the TSIO360LB1B 65# lighter than the TCM as well.  Pick up 25HP and lose a little weight. Automatic waste gate. Burn Jet A sounds like all amazing things. 
 

Could potentially solve all the issues with the 231’s engine management. And useful load. Maybe even give an option for a second alternator!
 

 There is an option to vote for the 231 to be their next STC. 
 

https://www.deltahawk.com/survey/

 

 

Edited yesterday at 03:35 AM by Crawfish
More thoughts

[1980Mooney]

10 hours ago, Hank said:

Wow! Just over half the displacement, and almost a third heavier. Not sure I can take an extra 75 lb on the firewall, and they cleverly don't say if the 335 lb weight includes oil and coolant. Lycomung advertises 258 lb dry weight, and 6 quarts of oil is ~9-10 more pounds. 

One reason it is heavy is because of the mechanical supercharger.  Everyone, even Deltahawk, keep highlighting "turbocharging and supercharging" as if it provides additional power while flying.  The mechanical supercharger is there for starting on the ground and restarting at altitude.  Once the engine rpm increases and the turbocharger spins up, the mechanical supercharger is disengaged via an electric clutch.  If you run a tank dry in cruise, the Deltahawk engine cannot restart without the supercharger.  It also provides 50% power if the turbocharger fails.  So once you hit the throttle, the supercharger just becomes dead weight.

Also Piper says "the aircraft will have an advanced cabin temperature control system utilizing the engines’ liquid cooling,".  That sounds like running coolant into the cabin utilizing heat exchangers inside the cabin like a car.  That is more complexity, more weight and the chance for a leak.

[Slick Nick]

8 hours ago, 1980Mooney said:

One reason it is heavy is because of the mechanical supercharger.  Everyone, even Deltahawk, keep highlighting "turbocharging and supercharging" as if it provides additional power while flying.  The mechanical supercharger is there for starting on the ground and restarting at altitude.  Once the engine rpm increases and the turbocharger spins up, the mechanical supercharger is disengaged via an electric clutch.  If you run a tank dry in cruise, the Deltahawk engine cannot restart without the supercharger.  It also provides 50% power if the turbocharger fails.  So once you hit the throttle, the supercharger just becomes dead weight.

Also Piper says "the aircraft will have an advanced cabin temperature control system utilizing the engines’ liquid cooling,".  That sounds like running coolant into the cabin utilizing heat exchangers inside the cabin like a car.  That is more complexity, more weight and the chance for a leak.

Diesels don't run nearly as hot as gas engines, and they take forever to warm up. An electric heater would be the best option, but I also come from the Janitrol era of aviation, so I'll see how this works in practice. 

[EricJ]

10 hours ago, 1980Mooney said:

Also Piper says "the aircraft will have an advanced cabin temperature control system utilizing the engines’ liquid cooling,".  That sounds like running coolant into the cabin utilizing heat exchangers inside the cabin like a car.  That is more complexity, more weight and the chance for a leak.

I was thinking they could leave the heater core in the nacelle, or even in the wing root, and just run air through it into the cabin rather than run coolant into the cabin.  I'm curious to how it is actually done.