Modern avionics in bush planes : Overkill?

[ckyliu 1,749]

2 hours ago, Dominique_K said:

 Nobody ever tried to design an electronic regulated  fuel injection in a piston engine  ?

There are electronic fuel injected and electronic ignition engines with FADEC available for GA use that have automatic mixture control. But aviation customers are conservative, R&D and certification is expensive which is why there's still plenty of newish stuff using carburettors, magnetos, fully air cooled, pushrod, lead fuelled, low compression, low rpm direct drive. Also aircraft tend to be quite long lived, so plenty of GA airframes from the 70s and 80s flying about.

Lycoming (e.g. O-360. Most of the O-540 are at least injected but I don't think it's electronic) and Continental (e.g. O-320. O-520 generally injected but again mechanical, the IO-360 has been available with FADEC for a while) design isn't all that far removed from the 1960s, and those two engine builders power the bulk of the world's general aviation. The power density on these engines is frankly rubbish, the O-360 you get in a new Archer needs 5.9L displacement to give just 180 hp.

A more modern piston aero engine would be Rotax 912 which has twice the power density (80 hp from just 1.2L without a turbo) or an Austro diesel.

Edited August 5, 2020 by ckyliu

[Dominique_K 10,149]

1 hour ago, ckyliu said:

There are electronic fuel injected and electronic ignition engines with FADEC available for GA use that have no mixture control. But aviation customers are conservative and certification is expensive which is why there's still plenty of newish stuff using carburettors, magnetos, fully air cooled, pushrod, lead fuelled, low compression, low rpm direct drive. Also aircraft tend to be quite long lived, so plenty of GA airframes from the 70s and 80s flying about.

 l.

Thanks for putting it in perspective. Chris remarks puts light on something under my nose that I never thought of. That piston engines are somewhat way behind turboprops which do have automatic barometric  fuel control ! Even with expensive avionics. Weird.

[snglecoil 1,828]

@Dominique_K, building on what @ckyliu so perfectly laid out. As someone contemplating an airplane purchase, it really comes down cost. Piston engines are really very simply designed for the most part. That helps to keep the cost of maintenance...and inspection...low-ish enough to give a person at least shot at affording to own and operate one. For any potential upside that an electronically controlled engine may offer, the additional cost associated with certification, purchase, and complexity of maintenance hasn't really driven demand for it. And now that electric propulsion is showing that it may be viable in the next 10-20 years (optimistically), maybe that will prove to be the true successor to the current engine technology. Electric could definitely be more expensive to purchase, but my understanding is that the cost to operate would make up the difference and give the compelling case to drive demand.

[Dominique_K 10,149]

1 minute ago, snglecoil said:

@Dominique_K, building on what @ckyliu so perfectly laid out. As someone contemplating an airplane purchase, it really comes down cost. Piston engines are really very simply designed for the most part. That helps to keep the cost of maintenance...and inspection...low-ish enough to give a person at least shot at affording to own and operate one. For any potential upside that an electronically controlled engine may offer, the additional cost associated with certification, purchase, and complexity of maintenance hasn't really driven demand for it.  

I am sure that you and @ckyliu reflect the general thinking in the aviation world.  

Lets put aside turbines which are expensive pieces of kit and somewhat more fragile than your rugged piston engine. Comparaison n'est pas raison, as we say in French, but cars have had electronic fuel injection for a long time now. The effects on price, reliability and maintenance are not obvious.  Also somebody able to put, say 150K USD in a plane, couldn't pay a few thousand more to have a a barometric controlled fuel injection instead of doing  the mixture manually from the cockpit (which is fun btw) ?  Again, I do not deny that you are right and don't want to be argumentative as it is the world as it is right now but it just seems weird to me. 

[snglecoil 1,828]

43 minutes ago, Dominique_K said:

don't want to be argumentative

I would never classify any discussion with you as argumentative, Dominique.

55 minutes ago, Dominique_K said:

Also somebody able to put, say 150K USD in a plane, couldn't pay a few thousand more to have a a barometric controlled fuel injection instead of doing  the mixture manually from the cockpit (which is fun btw) ?

There's a saying that the cheapest part of owning an airplane is the initial purchase 😢

[BrianW 124]

Don't forget weight is a very important part of the equation too. Every little bit impacts both performance and operating cost.

[n4gix 4,947]

18 hours ago, Dominique_K said:

I think that it was a wrong manipulation of a mod  but I would like to be sure.

Dom, to solve the mystery this happened because I tried (and obviously failed) to move/merge those two post back to the correct thread. So, throw any rocks at me... <blush!>

Mea maxima culpa. +