Although it's taken awhile, I've come to appreciate the "styling" of the HJ - including the bulbous nose and overwing engines. It should give the Phenom and Citations a run for their money. I'm also looking forward to seeing the "real" numbers of those HF120's

Patrick, I think you should post the picture of the CJ with Honda engine conversion.

Will it be available as single pilot? Maybe someone on here will test fly one and give a report in the near future.

Here it is Brent

Treating this as a serious idea, a Citation retrofit, I have to say that it will never work. The routing of controls, fuel, bleed air, electrical is simply not allowed for in the wing design, nor the application of thrust at that point in the airframe.

If a Citation gets Honda engines, they will be mounted on traditional tail pylons where the original engines were. That may make sense depending on the cost and performance of the Honda jet engines.

Mike C.

Hey Mike,

Sierra Industries is already working on an HF120 re-engine program for the CJ 525 - and no, it's not an overwing design


Treating this as a serious idea, a Citation retrofit, I have to say that it will never work. The routing of controls, fuel, bleed air, electrical is simply not allowed for in the wing design, nor the application of thrust at that point in the airframe.

If a Citation gets Honda engines, they will be mounted on traditional tail pylons where the original engines were. That may make sense depending on the cost and performance of the Honda jet engines.

Mike C.

Treating this as a serious idea, a Citation retrofit, I have to say that it will never work. The routing of controls, fuel, bleed air, electrical is simply not allowed for in the wing design, nor the application of thrust at that point in the airframe.

If a Citation gets Honda engines, they will be mounted on traditional tail pylons where the original engines were. That may make sense depending on the cost and performance of the Honda jet engines.

Mike C.

It will be interesting to see what the economics of the Honda engine is. That could shake up the industry if it is materially more cost effective than the Williams.

Mike C.

Bottom line in economy for fanjets is really easy to spot: when the fan stage is this small, there can be no greater fuel economy. To have a fuel efficient fanjet you need to do two things - have a big fan that moves a lot of air, and a high compression stage core. A high bypass ratio. That's why the airliners with the GE9x 777's, Airbus new Neo program etc, have ever bigger fan stages. The new fanjets are basically becoming ducted multiblade turpoprops. The core, the pure jet stage, contributes very little to the propulsion of the engine today, it's the cold stage, the big fan that does almost all the propulsive lifting.

It works for props as well. What every helicopter engineer will tell you is that the bigger the rotor, the less hp is required to hover for any given weight combo. Same for aircraft - a bigger prop will always be more efficient than a smaller one. You want to displace as much air as possible.

The Hondajet engines looks just as big as the FJ44 which makes me pretty certain it's no more fuel efficient than that. There might be other advantages to it, like price or build quality, but fuel efficiency compared to others will not be it's selling point.

So by this measure, the Tbone should be the most efficient light twin on earth.

Why?

The HF120 utilizes next gen technology, including advanced metallurgy and a few other advances in this class of turbofan powerplant. Still interested in the long term efficiency of the engine...

Why?

Doesn't run out like TKS/Alky can
Doesn't load up the generators like electric would.
Generally works better than boots.[/quote]

What is bad about it? Do most jets use bleed air?

The small turbojets like the PW610 on the Eclipse and Mustang don't have excess bleed air to give to the wing heat so they used boots.

Using bleed air for wing heat reduces thrust and performance. Some jets have tried to get max performance by using TKS on the leading edges. But that turned out to not be very popular.

Using wing anti-ice in my CJ2+ reduces climb by about 500 fpm. Not a big deal near SL but if in the clouds at FL300 and above with high ISA climb rate can get real doggy.