Settle the Bet

[FlyFlyFly]

Anyone know of a turbofan engine other than the GE CF700 where the priumary measure of power is EPR?

 

[Gulfstream 200]

How about the BMW-Rolls Royce BR700?

 

[cheater1239]

most any pratt&whitney uses EPR jt8, jt9, 2037, 2040, etc

 

[falcon20driver]

Do you remember the Air Florida 737-200 crash?

They set takeoff EPR, that is the primary power setting in the 737-200 Pratt JT8D, if they would have crosschecked the N1 and seen they were only at around 60 percent they would have added power and said the heck with the EPR setting, and they wouldn't have crashed and went into river.

 

[falcon20driver]

Here are the Air Florida NTSB reports

http://ntsb.gov/ntsb/GenPDF.asp?id=DCA82AA011&rpt=fa

http://ntsb.gov/ntsb/GenPDF.asp?id=DCA82AA011&rpt=fi

 

[falcon20driver]

I was wrong, they did note an engine instrument reading anomaly, so they new something wasn't right but they continued the takeoff instead of aborting. The new 737 primary power setting is N1, no more EPR gage.

Here is the Synopsis

http://ntsb.gov/ntsb/brief.asp?ev_id=20020917X01907&key=1

 

[gear_guy]

I think he said turbo fan.

 

[falcon20driver]

I think he said turbo fan.

I didn't catch that part.

Now I have a question, is the CF700 the only turbofan with the fan in the back?

 

[mattpilot]

i'm a fan of any angine that has a turbine

 

[Brett Hull]

Hopefully a Tri-Star driver will confirm this, but I think the RB-211 is another one.

And the GE CJ805 on Convair 990's is another aft-fan engine.

 

[Typhoon1244]

I think he said turbo fan.

Uh, the JT8D is a turbofan.

 

[DCitrus9]

jt8d is considered a jurboJET. The fan does not produce any appreciable thrust (5%?) compared to a turbofan. With the BR715 EPR is the primary control for the fadec, N1 is the reversion when sans computer.

 

[TrafficInSight]

jt8d is considered a jurboJET. The fan does not produce any appreciable thrust (5%?) compared to a turbofan. With the BR715 EPR is the primary control for the fadec, N1 is the reversion when sans computer.

Hmm... I don't think I've ever seen it called anything but a low bypass turbofan...

can you provide some sources?

 

[furloughfodder]

How 'bout the JT9D Pratt & Whitney dual-spool \ axial flow \ high bypass Turbofan?

Fan produces 75% of the 52,000 lbs of thrust with a 5 to 1 bypass ratio.

...at least that's what somebody told me

 

[TrafficInSight]

How 'bout the JT9D Pratt & Whitney dual-spool \ axial flow \ high bypass Turbofan?

Fan produces 75% of the 52,000 lbs of thrust with a 5 to 1 bypass ratio.

...at least that's what somebody told me

That's fine for a JT9D but we're talking about JT8D's

 

[Torqued]

The JT8-D is a turbofan, but has a low bypass ratio of about 1.7 to 1. Never heard of it called a turbojet.

 

[dash8driver]

some people like their cucumbers pickled...

 

[Typhoon1244]

jt8d is considered a jurboJET.

By who? You?

The fan does not produce any appreciable thrust (5%?) compared to a turbofan.

The JT8D is a turbofan. The 1.7-to-1 ratio Torqued mentioned is about right.

Now if it had no fan at all, then you could consider it a jurbojet.

(You have actually flown the '9...right?)

 

[FlyFlyFly]

OK, this is a neat discussion, let me try my question again:

Are there any turboFAN (I did say FAN and not JET) engines out there where the primary measure of power is EPR, other than the CF700?

I conclude that the JT8 is arguably a turbofan, so it would qualify, therefore do you set power on it primarily by EPR? I assume the JT8 is that ultra low bypass affair of a stovepipe slung under the wings of 737-100 & 200s.

It also appears that the BR715 has a FADEC that uses EPR to set power, so I would assume the BR710s on a GV would have the same.

Any others?

 

[DCitrus9]

Doh!

Disregard, I was coming in broken and stupid!

Due to the late hour and several coors lights, my post is factually innaccurate regarding turbojet. I've been off of the 9 for a few years, and am simply too lazy to look it up.

 

[DCitrus9]

Low bypass (3%) vs high bypass is what I was thinking of when I inserted foot into mouth. I know that the jt8d is a turbofan.

 

[TriStar_drvr]

Hopefully a Tri-Star driver will confirm this, but I think the RB-211 is another one.

That is true on both the -22B and the -524B4 installed on the -100 and -500 series L-1011s. I think a varient of RB-211 is installed in many 757s. As many times as I've ridden in the cockpit of Rolls Royce powered 757s, I can't remember if power is set by EPR or N1. My guess is N1.

 

[TonyC]

Pratt & Whitney TF-33's on the RC-135's I used to fly set EPR's...


(I don't recall any specific numbers about ratios, etc., but I'm sure we called them turbofans....)


Some MD-11's and some Airbus products on our ramps use the P&W 4462's, and they use EPR as the primary reference to set power.

(Again, I don't know specific ratios, but I'm certain they're much higher than the TF-33's)

As the only TRUE direct measure of thrust, I kinda like EPR's.