|Quoting BrowntailWhale (Reply 5):|
The way it works is this, with the gear up, only #2 and #3 can be reversed. They can go up to max thrust. With the gear down all four can be reversed up to max thrust
Actually, what you wrote does not apply to all DC-8s, and is not true regarding any of the 60-series and older DC-8s that UA
had. Perhaps what you said applies to the 70 series with the CFMs? Here's a breakdown of the models I have information on:
THRUST BRAKE LIMITATIONS--IN FLIGHT
--The -10 series, with JT3C engines could go to max continuous power on all four, regardless of the gear position.
--The -20 and -30, with JT4A engines could go to max continuous power on #2 and #3, and had mechanical stops which limited #1 and #4 to approx. 31% of max continuous power (gear up or down) until there was weight on wheels, at which point #1 and #4 could go to max continuous.
--The -40 I have no information about. Sorry RR
--Most -54F, and all -61, with JT3D turbofans could use #2 and #3 up to max continuous. On #1 and #4, no reverse with gear up, limited to idle reverse by mechanical stops with gear extended. With weight on wheels, #1 and #4 could to go max continuous.
--All the other -50 series not covered above, and all -62 with JT3Ds could use #2 and #3 up to max continuous, #1 and #4 were locked out of reverse, even with gear down, until there was weight on wheels.
--I have no info for the -63 or any of the -71/72/73.
--Max speed for extending ejectors and/or using thrust brakes: 390kts.
--Max speed for retracting ejectors (JT4A): 250kts.
--Thrust reversers must not be used in flight below a speed of 200kts.
--Wing flaps must be completely retracted for all inflight thrust brake applications.
FYI, all this information was taken from a UA
DC-8 flight manual.
Don't blame me, I don't work here...