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NEWS Drop-in wonder engine?

Pags

Pope of Chili Town
pilot
The big improvement to engines that could actually be used in legacy airframes is better high/hot performance (read that as less/no degradation not an increase in max output) and better fuel economy. I would argue improving the latter by a significant amount would yield better results.
Is it even possible to develop a turbo shaft that doesn't degrade at high altitude?

My education says I should know this but it's been awhile. I know there are types of jet engines that are optimized for high altitude performance but they suffer at low altitude. Same thing for piston engines; it's hard to develop an all around performing engine due to the changing properties of air.
 

Beans

*1. Loins... GIRD
pilot
Is it even possible to develop a turbo shaft that doesn't degrade at high altitude?
No. Simple matter of how much air you can get through the hole in the front of the engine. Speed, size, density are the factors. As you go up (or get hotter, or get less dense), the less O2 you can get in that hole. The less O2 you suck in, the less fuel you add to it (lest you "roll coal" on your climb, compensating for something while looking like you're on fire). The less fuel you add, the less energy you get out of your engine.

I'm washing over a bunch of other factors (not even getting to the prop side of things)... but none of that's inaccurate.

My education says I should know this but it's been awhile. I know there are types of jet engines that are optimized for high altitude performance but they suffer at low altitude. Same thing for piston engines; it's hard to develop an all around performing engine due to the changing properties of air.
Optimized =/= more power. Those engines might have a better specific fuel consumption (how much thrust you get per pound of fuel burned) at certain altitudes and temperatures.
 

busdriver

Well-Known Member
None
I was thinking a FADEC controlled de-rated engine. Control the spool up time, max torque, and whatnot to make it mimic a lower powered engine at low altitude to keep the dynamic components from fragging, but give you more oomph at altitude. Most pilots would probably shit if their new engine was capable of XXXX horsepower, but "they" decided to de-rate it to YYYY.

I still think improved burn rates would be more beneficial, a 25% reduction in fuel flow would get you something like 550 lbs/3.3%/40 minutes depending on how you chose to use it.
 

Gatordev

Well-Known Member
pilot
Site Admin
Contributor
I'm asking this in the hope the answer uses simple, one or two-syllable words written at the high-school level...

How is a FADEC different from the combination of the CEDECU/HMU combination? I understand the HMU is a hydro-mechancial adjustment, and not an electrical one, but with the ECUs in the mix, does that constitute some sort of pseudo FADEC? At the end of the day, the fuel has to be regulated by a valve with either system, so I'm just trying to understand where the distinction is.
 

Beans

*1. Loins... GIRD
pilot
I'm asking this in the hope the answer uses simple, one or two-syllable words written at the high-school level...
ON IT.
How is a FADEC different from the combination of the CEDECU/HMU combination? I understand the HMU is a hydro-mechancial adjustment, and not an electrical one, but with the ECUs in the mix, does that constitute some sort of pseudo FADEC?
Yes.
At the end of the day, the fuel has to be regulated by a valve with either system, so I'm just trying to understand where the distinction is.
Take out HMU, put HMU inputs and outputs in new, more better DECU. Now DECU is FADEC.

We're probably using DECUs because they allow us to use the T700s with their carburetor-era HMUs without changing too much about the engines.
 

IKE

Nerd Whirler
pilot
Like many other terms, FADEC has a specific definition and very fuzzy or wide usage. As I understand it, there are three features generally included in FADECs which are not currently implemented in the T700 (including (C)EDECU models):

1) Fully automatic start (single button push)

2) Torque limiting (and possibly other limiting that isn't traditionally handled automatically)

3) Improved accel/decel performance. Without getting too nerdy, the FADEC has a better model of the engine in its brain and can better monitor numerous parameters, so it can push closer to stall/surge limits. This gets you more power, more quickly without choking.
 

jtmedli

Well-Known Member
pilot
Is it even possible to develop a turbo shaft that doesn't degrade at high altitude?

My education says I should know this but it's been awhile. I know there are types of jet engines that are optimized for high altitude performance but they suffer at low altitude. Same thing for piston engines; it's hard to develop an all around performing engine due to the changing properties of air.
I was thinking about this and the only thing I can think of is maybe if you actively control the compressor vanes then you could optimize the intake for higher PA. But as others mention, I think we're also talking about better rotor blades being just as necessary as better engines also (?).
 

Gatordev

Well-Known Member
pilot
Site Admin
Contributor
Take out HMU, put HMU inputs and outputs in new, more better DECU. Now DECU is FADEC.
DECUs? That's SO legacy. Now we have what I refer to as "LMNOPECUs." Disclaimer: IKE might have a more accurate nomenclature in his post.
 

Beans

*1. Loins... GIRD
pilot
Well, the current setup for T700s, with an HMU and whatever computer you've strapped on it, is like taking a modern automobile engine control (circa 90's is what I mean by modern) and using it to control a carburetor. So you can optimize the carburetor's performance, but it's still a carb, and not fuel injection.
 

IKE

Nerd Whirler
pilot
Is it even possible to develop a turbo shaft that doesn't degrade at high altitude?

My education says I should know this but it's been awhile. I know there are types of jet engines that are optimized for high altitude performance but they suffer at low altitude. Same thing for piston engines; it's hard to develop an all around performing engine due to the changing properties of air.
It's also hard, I imagine, to meet arbitrary specs. The most fuel-efficient operating point for a typical engine is in the higher ranges of Ng (N1). This is why singling up gives you better range (and why -53 dudes I've asked hate that their leadership won't let them shut down #3 in flight).

If you build an engine that puts out enough power to hover at 6k ft and 95 °F, it probably sucks down too much fuel at SL and 59 °F. All of this can get better with fancier engines (more moving parts and more complicated engine control), but in the end, any engine has a single "design operating point."
 

Randy Daytona

Cold War Relic
pilot
Super Moderator
Another interesting development if no one else has seen it pertaining to the Bell 212 (Twin Huey)

The Eagle conversion for the Bell 212 - basically pull out both P&W PT-6's and the C-Box and install a single, much bigger engine. T-53 Engine HP rating is 1800 at sea level, transmission rating (at takeoff power) is 1290 HP.

http://www.eaglecopters.com/pdf/Eagle Single Certs/Brochure_SINGLE.pdf

I was thinking about this and the only thing I can think of is maybe if you actively control the compressor vanes then you could optimize the intake for higher PA. But as others mention, I think we're also talking about better rotor blades being just as necessary as better engines also (?).
I am sure they are working on that. As it stands, every blade design is a compromise between hover performance and forward flight. NASA may be able to change that for us - I will leave this for the test pilots here to expound upon.

http://www.nasa.gov/topics/aeronautics/features/smart_rotor.html
 
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