This is pretty sweet!

[Robbiee]

You Tube

For when AVGAS goes the way of the Dodo.

[Ascend Charlie]

Doesn't compute...

[aa777888]

Holy crap! I want one! That's awesome!

[tartare]

What's the small tube running down the rear of the right skid that seems to be venting a small amount of exhaust?

[gulliBell]

Why might it need a clutch if it has a turboshaft engine?

[krypton_john]

Originally Posted by gulliBell

Why might it need a clutch if it has a turboshaft engine?

It's probably a fixed spool turbine so the output shaft is the same as the compressor...

[212man]

Originally Posted by krypton_john

It's probably a fixed spool turbine so the output shaft is the same as the compressor...

Yes, correct - as you would expect for an APU.

I see the same idea has been used elsewhere: https://www.laehelicopterscyprus.com/piranha.html

[Bell_ringer]

APU driven ultralights aren't new.
https://www.famahelicopters.com/index.php/en/kiss-216

[212man]

It seems like pretty dodgy ground really, as these units are not designed as propulsion devices and are not designed or certified as such. Here is an extract from the FAA TSO qualification standards:

The standards of TSO C77b apply to gas turbine engines intended to provide auxiliary electrical, pneumatic, or mechanical power to support airplane systems operations. These standards do not apply to gas turbine engines intended for aircraft propulsion nor do they address the integration of the APU into the design of the airplane.

[Bell_ringer]

Originally Posted by 212man

It seems like pretty dodgy ground really, as these units are not designed as propulsion devices and are not designed or certified as such. Here is an extract from the FAA TSO qualification standards:

That's why they fit into experimental or restricted use categories.

[SASless]

The FAA used to require systems like PBA on the Sikorsky 76....but no longer do.

Just because the FAA requires something does not mean they are on top of things....it just shows what the current regulation requires.

I remember when Soloy began to add Turbine Engines to Hillers and General Aviation Airplanes....that caused the FAA some discomfort but we see how that turned out.

Technology moves forward.....Certification Authorities always lag behind technological advances.

A good example is the FAA and helicopter fly by wire designs....industry had the engineering to move forward and the FAA did not have the equal expertise to craft the certification requirements and the industry had to teach the FAA what it needed to know to accomplish that.

Bottom line....it is still a Robbie that can carry a hundred kilo's of useful load due to the lighter engine.

[212man]

The FAA used to require systems like PBA on the Sikorsky 76....but no longer do.

The PBA was for a specific requirement about longitudinal stability and stick force gradient - I don't think the requirement to demonstrate compliance, has gone, it just depends on the type and how it is achieved, whether naturally or artificially.

Technology moves forward.....Certification Authorities always lag behind technological advances

This is hardly a question about technology. We are talking about a 50+ years old APU that was designed to run for short periods, and fairly steady demand, whilst on the ground, with a much lower requirement for component failure probability. It is now being used with variable power demand, over long periods, in widely changing atmospheric conditions and experiencing dynamic loads, such as gyroscopic precession (64,000 RPM turbine!), it MAY not have been demonstrated or designed to meet.

[SASless]

Quoting from an earlier post by Bell Ringer......

That's why they fit into experimental or restricted use categories.

Perhaps in time it be certified for its new use.

As to PBA....plenty of discussion about that another thread.

[MarcK]

APU powered experimental helicopters have been around for a long time: Rotorway JetExec

[Ascend Charlie]

a Robbie that can carry a hundred kilo's of useful load due to the lighter engine

So, now those porky Murricans can train in this instead of the R44 Cadet.

[Robbiee]

Originally Posted by Ascend Charlie

So, now those porky Murricans can train in this instead of the R44 Cadet.

,...and build up that turbine time while doing it.

[Agile]

With 100Kg less at the back and Claude in front you better watch your CG
Now get on to fix the mast bumping limitation...

[Ascend Charlie]

Yeah, spend the money putting a Hughes/ Schweizer 300 rotor head on it, or even a (barrff!) Enstrom head.

[cattletruck]

This one even has a C20 inside.

https://en.wikipedia.org/wiki/Schweizer_S333

[Robbiee]

Originally Posted by Ascend Charlie

Yeah, spend the money putting a Hughes/ Schweizer 300 rotor head on it, or even a (barrff!) Enstrom head.

We're trying to upgrade the 22 here, not downgrade it.