Jet-A fuelled 180HP piston-engine type-certified

[Garfly]

 

 

 

DeltaHawk Gains Type Certification on Jet-Fueled Piston Powerplant - FLYING Magazine

WWW.FLYINGMAG.COM

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The ‘upside down’ DeltaHawk DHK180 piston powerplant set to run on jet-A has gained FAA type certification.

 

[Thruster88]

I really like 2 stroke engines. It might be a turn off for some potential buyers.  

[Garfly]

To me, it's interesting that big investment continues to go into new alternative-fuel ICEs just as unleaded petrol is coming online.

I wonder at the business model but it must make sense, somehow.  

According to the article "according to the company" there's significant interest from the military and also from "kit builders".

It'll also have to compete with the new similar sized, similar priced (?) turbines using the same fuel - and maybe not all that much more of it per mile.  

[skippydiesel]

I wonder why both turbo & super charged?

 

Surly one or the other (particularly super charger) would achieve the desired pressures

[onetrack]

Ohhh!! ... the noise!! ... my ears!!!  Notice how no-one - especially the DH manufacturing people - have even made a passing reference to the engine noise!!  The Detroit Diesel of aviation!!

 

You'll need double levels of insulation, double-layers of window polycarbonate - and the "aircraft noise" whiners on the ground, will have a whole new major level of opposition!!

 

In addition, I didn't notice anyone asking about the cabin heat levels associated with having a glowing cherry-red turbocharger mounted right against your firewall!! Double levels of heat insulation needed, too!!

 

 

 

[Thruster88]

2 hours ago, skippydiesel said:

I wonder why both turbo & super charged?

 

Surly one or the other (particularly super charger) would achieve the desired pressures

My guess is the air doesn't go into the crank case like a regular 2 stroke so it needs an external air pump at all times. Super charged for starting, turbo for altitude performance.  

 

Super chargers sap horsepower so that needs to be kept to the minimum required.  

Edited May 21, 2023 by Thruster88

[facthunter]

You have to scavenge a two stroke positively, especially IF you are not involving the crankcase as away of doing it.. You don't need a lot of boost to do that if that's the way you go. You can use a more normal OIL system as well. Starting would have to provide boost before the motor was started. Either a rotor(s) positive displacement engine driven blower or electric? The TURBO only works once the motor is running.  Lots  of turbo's will damage your ears.  Nev

[skippydiesel]

6 minutes ago, Thruster88 said:

My guess is the air doesn't go into the crank case like a regular 2 stroke so it needs an external air pump at all times. Super charged for starting, turbo for altitude performance.  

 

Super chargers sap horsepower so that needs to be kept to the minimum required.  

Hmmm!

They both "sap" power.  It a trade-off,  in that the increase in volumetric efficiency, more than compensate for the lost power.

Without knowing the reasoning, I think your "starting" suggestion may be on the ball as its delivering  air compression from the moment the engine moves,  whereas an exhaust turbo will deliver little until the rpm rises.

I have no experience with superchargers (positive displacement air pumps) but would have speculated that it would be possible to use a single pump , regulated (like a waist gate) so as to perform as desired over an rpm/altitude range.

I understand that 2/ benefit, in particular,  from a blown system, as it helps both with air in and removing spent air/fuel out/exhaust (scavenging).

It would be interesting to know the unswear/thinking from the manufacturer

[facthunter]

Using words like SAP implies something very wrong with the idea.  any Pump has losses and requires energy. The dead strokes on a four stroke are pumping losses.  and you miss out on an extra power stroke the two stroke gives  but 2 strokes are nearly always less efficient. Nev

[Area-51]

5 hours ago, Thruster88 said:

My guess is the air doesn't go into the crank case like a regular 2 stroke so it needs an external air pump at all times. Super charged for starting, turbo for altitude performance.  

 

Super chargers sap horsepower so that needs to be kept to the minimum required.  

2 stoke diesels are generally supercharged to ensure enough air gets forced up through the ports to achieve required compression ratio and the turbo charger is there to restore and add to the drive energy the supercharger requests and robs.

 

It appears a well thought out piece, but it could be junk; hit n miss with yank built stuff often with disappointing quality seldom meeting expectations or advertised greatness.

[facthunter]

The blower is there to scavenge the products of combustion. You can only BOOST the volume if the  other port is closed at the same time. Just forcing more AIR in  doesn't do it.   Nev

Edited May 22, 2023 by facthunter

[Thruster88]

These guys have a turbocharged 2stroke.

 

https://www.rotax.com/en/products/rotax-powertrains/details/rotax-850-e-tec-turbo.html

[facthunter]

Nearly 200 HP? In your DREAMS. Be for a very short burst. Nev

[Blueadventures]

1 hour ago, facthunter said:

Nearly 200 HP? In your DREAMS. Be for a very short burst. Nev

121kW is about 160hp

[facthunter]

Still wouldn't be able to get the heat out of it for use in a plane. Pistons are problems in that type of motor when they are not boosted.  Nev

[BrendAn]

On 21/05/2023 at 10:35 AM, skippydiesel said:

I wonder why both turbo & super charged?

 

Surly one or the other (particularly super charger) would achieve the desired pressures

 

1991 – THE KAD CONCEPT

In 1991 Volvo Penta first launched the KAD concept. Combining a mechanical compressor and turbocharger produced both high maximum power and massive torque directly from low revs for impressive acceleration. The first two engines were the KAD42 with Duoprop and the inboard KAMD42. Both were a tremendous success, and the KAD42 quickly became the world’s best selling diesel Aquamatic.

volvo used a supercharger and turbo combination on a 4 stroke diesel. they have heaps of power to. this was actually for performance not as a blower like a gm.

Edited May 22, 2023 by BrendAn

[BrendAn]

2 hours ago, facthunter said:

Still wouldn't be able to get the heat out of it for use in a plane. Pistons are problems in that type of motor when they are not boosted.  Nev

well it is boosted and its in a snowmobile.  or are you talking about the diesel engine

Edited May 22, 2023 by BrendAn

[onetrack]

General Motors fitted turbochargers to their 2 stroke supercharged GM Diesel in the early 1960's. The GM nomenclature for the engine models was 1, 2, 3, 4, 6, 8, 12, 16 and 24 for the number of cylinders, "V" for Vee engines, "53", "71" or "92" for the cylinder size in cubic inches, and the last letter was either "N" for Naturally Aspirated, or "T" for turbocharged. So, a turbocharged 71 series V8 GM diesel was referred to as an "8V-71T". Around 1967, the GM Diesel became the Detroit Diesel.

 

The history of GM's 2 stroke diesel engines -

 

https://www.curbsideclassic.com/automotive-histories/truck-history-1939-gmc-first-year-for-the-legendary-jimmy-detroit-diesel-its-still-being-built-85-years-later/

 

 

And of course ... only in America - a V16, 2 stroke, 71 series turbocharged Detroit Diesel engine producing 875HP, installed in a homebuilt hotrod.

 

 

[BrendAn]

11 minutes ago, onetrack said:

General Motors fitted turbochargers to their 2 stroke supercharged GM Diesel in the early 1960's. The GM nomenclature for the engine models was 1, 2, 3, 4, 6, 8, 12, 16 and 24 for the number of cylinders, "V" for Vee engines, "53", "71" or "92" for the cylinder size in cubic inches, and the last letter was either "N" for Naturally Aspirated, or "T" for turbocharged. So, a turbocharged 71 series V8 GM diesel was referred to as an "8V-71T". Around 1967, the GM Diesel became the Detroit Diesel.

 

The history of GM's 2 stroke diesel engines -

 

https://www.curbsideclassic.com/automotive-histories/truck-history-1939-gmc-first-year-for-the-legendary-jimmy-detroit-diesel-its-still-being-built-85-years-later/

 

 

And of course ... only in America - a V16, 2 stroke, 71 series turbocharged Detroit Diesel engine producing 875HP, installed in a homebuilt hotrod.

 

 

listen to that sound, magnificent.   i used to have a detroit diesel ringtone.  they are not supercharged though. its a scavenger blower. even a naturally aspirated gm still has one. won't run without it, not very well anyway.

Edited May 22, 2023 by BrendAn

[skippydiesel]

Most ground based vehicle engines are optimised for acceleration -

Single turbo charged engines use"compromise" turbos, that is they will spool up fast enough to achieve an acceptable amount of power, from low rpm and still be delivering a bit of puff at higher rpm.

Fancy sports care started using two turbos, one to get things going from low rpm and a second to keep the power coming at higher rpm (less compromise but way more complexity). The technology trickle down effect has meant that less exotic cars now may have two turbos.

The power delivery demands of a road vehicle  and most boats (closer) can not be easily compared with that of an aircraft.

I would suggest that two turbos, in an aircraft application, will have more to do with the availabity of space, than performance. Most aircraft do not accelerate from low rpm (like a car/motorcycle) - if they are turbo'd it is for increased power from a nominated cylinder capacity (volumetric efficiency) and or altitude performance (turbo normalised).

As I understand 2/ they have a great power to weight (compared with a 4/) but are not so fuel efficient and generally have poor torque characteristics. Add a blower, of any description and you greatly increase the 2/volumetric efficiency (power/torque) while also improving scavenging (the removal of waist gas/exhaust) - the combination brings the 2/ close (better?) to the fuel efficiency of a 4/ while maintaining its excellent power:weight.

I can understand the desirability/need for the Delta Hawk to be blown but not why it needs/benefits from two .

[onetrack]

It's all about maximising the power output for the engine size/weight. The more air (oxygen) you can pump into a diesel, the more power you get, it's really that simple. And with more air available, you can ramp up the level of fuel delivery by way of injecting more diesel on each injection stroke. In addition, turbochargers utilise the energy in exhaust gas flow that is otherwise simply wasted.

 

Furthermore, the hotter the exhaust gas temperature, the more efficient a turbocharger becomes, as the exhaust gases expand, and this drives the turbo faster.

 

One of the things that surprised me about the DeltaHawk engine is that they're not utilising staggered injection pulses. This system is common on many diesels today, and it reduces diesel "rattle" and "knock", improves fuel economy, and it is reliable, despite using electronics to govern the number of injection pulses. 

 

Edited May 22, 2023 by onetrack

[walrus]

Onetrack, it has mechanical injection. No electronics.

 

 

[skippydiesel]

10 hours ago, onetrack said:

It's all about maximising the power output for the engine size/weight. The more air (oxygen) you can pump into a diesel, the more power you get, it's really that simple. And with more air available, you can ramp up the level of fuel delivery by way of injecting more diesel on each injection stroke. In addition, turbochargers utilise the energy in exhaust gas flow that is otherwise simply wasted.

 

Furthermore, the hotter the exhaust gas temperature, the more efficient a turbocharger becomes, as the exhaust gases expand, and this drives the turbo faster.

 

One of the things that surprised me about the DeltaHawk engine is that they're not utilising staggered injection pulses. This system is common on many diesels today, and it reduces diesel "rattle" and "knock", improves fuel economy, and it is reliable, despite using electronics to govern the number of injection pulses. 

 

 

I am not questioning the purpose of air charging/boosting, I am asking why the need for two methods (turbo & super charging) of achieving this on the one engine - I am sure there is a logical reason I just don't know what it is.

[onetrack]

Skippy - Because the supercharger is simply necessary to scavenge the combustion chambers - but the turbocharger is there to improve the power level and efficiency, by utilising the waste exhaust gases. Two different accessories with different jobs to do. 

[onetrack]

Walrus - Yes, I got that part about the DeltaHawk design and design principles being mechanical fuel injection and for simplicity/reliability. But the bottom line is that electronically-controlled common rail diesel fuel injection, with piezo injectors, is a highly efficient, mature and reliable arrangement, that is used on virtually every current model diesel engine, and there's no real reason why the system can't be used on a new design aircraft engine.

 

Even the major aircraft engine manufacturers are now turning to FADEC controls on their latest engines - they simply need to be dragged out of the dark ages of 1930's engine design that they won't let go of, and embrace the fact that modern electronic controls are highly reliable, if properly designed, properly installed, and properly maintained.