Real Thrust Reverser for CitationJets
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Real Thrust Reverser for CitationJets
So the various models of CJs have thrust attentuators, but no real thrust reversers. If you fly a CJ (CJ, CJ1, CJ1+, CJ2+, CJ3, CJ4) or Premier I would you pay for actual thrust reversers for contaminated runway controllability, reduction of brake/tire wear, etc?
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Pretty slow flying jets, are reversers really needed on Citations?
Not that effective anyway. Some big jets never had 'em.
Like having anti-skid on a C-172, sure ya need that..?
Not that effective anyway. Some big jets never had 'em.
Like having anti-skid on a C-172, sure ya need that..?
It's all relative surely?
Yes a relatively slow Jet ( slotation ) but how big are the brakes? How long are the runways it flies into?
It's approach speed must still be around 110kts or so?
Runways 4000' look short I imagine, especially when wet.
Yes a relatively slow Jet ( slotation ) but how big are the brakes? How long are the runways it flies into?
It's approach speed must still be around 110kts or so?
Runways 4000' look short I imagine, especially when wet.
“reverse is very important, even life saving” and are you aware of the risks to be considered when relying on reverse?
The certificated landing performance for commercial aircraft does not normally consider the use of reverse unless the system can be shown to be highly reliable.
Reverse credit might be allowed for contaminated operations, but this is mitigated by reduced exposure where crews are expected make every effort to avoid the conditions, and that they know the risks and have procedures to minimise them.
Relying on reverse on contaminated runways can be like relying on a leaky life boat.
The certificated landing performance for commercial aircraft does not normally consider the use of reverse unless the system can be shown to be highly reliable.
Reverse credit might be allowed for contaminated operations, but this is mitigated by reduced exposure where crews are expected make every effort to avoid the conditions, and that they know the risks and have procedures to minimise them.
Relying on reverse on contaminated runways can be like relying on a leaky life boat.
It's all relative surely?
Yes a relatively slow Jet ( slotation ) but how big are the brakes? How long are the runways it flies into?
It's approach speed must still be around 110kts or so?
Runways 4000' look short I imagine, especially when wet.
Yes a relatively slow Jet ( slotation ) but how big are the brakes? How long are the runways it flies into?
It's approach speed must still be around 110kts or so?
Runways 4000' look short I imagine, especially when wet.
The 2's also had the option of target-type reversers (like on DC-9's but they added something like 180 kg to the ZFW so weren't a popular option.
Another option was a drogue parachute that was operated by a big hand-brake style lever on the cockpit floor. In the disarmed position the front of it was close to the Captain's seat, to arm it you pulled the end out towards the centreline of the cockpit so it could be lifted up. Sometimes they wouldn't work because the airframe was repainted in between parachute inspections and the drop-down door would be painted shut.
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CJ Reversers
I think what the op is trying to ask on this forum is whether or not operators would want such an option. Maybe he is trying to pursue an STC for the CJ and Premier line. Obviously reversers are are nice to have or almost every other manufacture out there wouldn't put them on in the first place. Yes I know that we aren't given credit for having them when determining landing performance (or at least all the types I have flown), but any help that one gets on stopping is a good thing. So it brings us back to questions at hand. Why didn't Cessna and Raytheon put them on to begin with? Was the weight and performance penalty too much to overcome for the small advantage of extra stopping? CJ's typically don't have a lot of extra payload to play with anyway. I'm not a CJ expert but didn't Cessna do away with the thrust attenuators after the CJ2? Seems to me that with such slow approach speeds, low mass, and good brakes that the engineers at Cessna deemed the advantage of reversers did not outweigh the disadvantages of the weight and performance (ie climb and cruise) penalty. My 2 cents worth.
Last edited by g450cpt; 13th May 2014 at 18:03.
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Basically brakes are cheaper, lighter, less complicated and more reliable than thrust reversers. Reversers only really work well at higher speeds and I don't think 100 kts counts (do these things really come in so fast?). Another thing to think about is the possibility of FOD damage. A proper reverser would pick up various bits rubbish which would either damage the airframe and/or the engine by way of re-ingestion. When operating into small airports, I would suggest that the chance of having moveable FOD in the braking zone would be quite high.
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(do these things really come in so fast?)
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All Cessna's basic weights are for one pilot, since it is a single pilot certificated aircraft. Still quite an optimistic figure for 1 + stores, though 
Also, for CJ2+ Vref at MLW is 106. The 86/112 figure would be for MTOW.
Also, for CJ2+ Vref at MLW is 106. The 86/112 figure would be for MTOW.
Last edited by BizJetJock; 13th May 2014 at 14:35. Reason: Added data re CJ2+ Vref
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CJ Thrust Attenuators
Thrust attenuator were used to eliminate idle thrust so you didnt have to ride the brakes and to reduce ground idle thrust during landing roll. That was it. Subsequent versions of the FJ44 engines allow for a different flight idle v ground idle thrust especially with the advent of the FADEC so attenuators went away.
You miss the point Saftyp.
While reverse is not factored into dry runway calculations it certainly is for wet or contaminated.
Besides that, most pilots like to have a little extra up their sleeve for when their performance is not perfect or conditions are worse / more critical than planned.
If you are planning everything to the razors edge you may be in for a
surprise
While reverse is not factored into dry runway calculations it certainly is for wet or contaminated.
Besides that, most pilots like to have a little extra up their sleeve for when their performance is not perfect or conditions are worse / more critical than planned.
If you are planning everything to the razors edge you may be in for a
surprise
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Single pilot trs
I believe that the main reason all those jets don't have trust reverses is because they are designed for single pilot operations...
Removing the TRs reduces a big problem when it comes to rejected takeoff single piloted because of tr, just one less thing to think about/do.
I've been flying a S/II for around 4 years in and out 900m runways, the tr sure make a difference.
Also, aerodynamic barke (such as tr and liftdump on a hawker) is always better because you save brakes and you can really feel the difference on wet runways..
Imri
Removing the TRs reduces a big problem when it comes to rejected takeoff single piloted because of tr, just one less thing to think about/do.
I've been flying a S/II for around 4 years in and out 900m runways, the tr sure make a difference.
Also, aerodynamic barke (such as tr and liftdump on a hawker) is always better because you save brakes and you can really feel the difference on wet runways..
Imri
