Turbo Prop go around
Thread Starter
Turbo Prop go around
I have been lucky enough to have to fly quite abit with my job, as I like aviation that's a plus.
Mostly flown on mainline jets but have always enjoyed the occasional trip on a turbo prop inc Viscount , F27/F50 Dash 7/8s and ATRs .
Turbo props can do col things like very short landings , very steep take offs, reversing on the runway to get every available foot of take of run (Anguilla) and I know they can control speed when slowing for an approach far better than jets can.
One thing , which I have not experienced though is what happens when a TP crew face a go around? I know that around 1500-100 ft on approach TPs go into fine pitch with a big change in engine note and what feels like quite an increase in revolutions.
So if we get to say 100 feet and a cow , pig , donkey. child on bicycle suddenly appears on the runway (since TPs often go to places where these things happen) what does the crew do , I don't think there is a TOGA button , or is there, I presume the intent is the same as on a jet, pitch up, incease power and clean up as it accelerates but how is that achieved with respect to the engines. Sorry for asking such a basic question but the thought struck me and has puzzled me all day.
Thanks
PB
I have experienced rather more than my share of jet go arounds but it never yet happened to me on a prop
Mostly flown on mainline jets but have always enjoyed the occasional trip on a turbo prop inc Viscount , F27/F50 Dash 7/8s and ATRs .
Turbo props can do col things like very short landings , very steep take offs, reversing on the runway to get every available foot of take of run (Anguilla) and I know they can control speed when slowing for an approach far better than jets can.
One thing , which I have not experienced though is what happens when a TP crew face a go around? I know that around 1500-100 ft on approach TPs go into fine pitch with a big change in engine note and what feels like quite an increase in revolutions.
So if we get to say 100 feet and a cow , pig , donkey. child on bicycle suddenly appears on the runway (since TPs often go to places where these things happen) what does the crew do , I don't think there is a TOGA button , or is there, I presume the intent is the same as on a jet, pitch up, incease power and clean up as it accelerates but how is that achieved with respect to the engines. Sorry for asking such a basic question but the thought struck me and has puzzled me all day.
Thanks
PB
I have experienced rather more than my share of jet go arounds but it never yet happened to me on a prop
I know that around 1500-100 ft on approach TPs go into fine pitch with a big change in engine note and what feels like quite an increase in revolutions.
Join Date: Apr 2012
Location: Colchester
Age: 40
Posts: 454
Likes: 0
Received 0 Likes
on
0 Posts
Turbo Prop go around
The Reduced NP on the Mighty Q tells the FADEC that you want to come in with lower power settings to sneak up on said cows and pigs. The condition levers are set already in the 1020rpm range and the FADEC is instructing the governors to maintain 850(or 900 if you're weird)rpm UNLESS the power levers are advanced above 50% torque. Then you get an automatic increase to 1020rpm for go-around.
Thread Starter
Many thanks folks, I did think that changing the pitch would do it but as nothing is for free I was not sure where the extra power would come from-ie the increase in fuel flow. Would that have been true in the days of RR Darts like Viscounts and F27s or would the crew have had to do a bit more work?
Thanks again PB
Thanks again PB
Join Date: May 2001
Posts: 10,815
Likes: 0
Received 0 Likes
on
0 Posts
The power out put of the prop is rpm times the torque.
So to get max power you need the props to be going as fast as possible and the torque to also be at max.
As for the go-around itself the aircraft with flight directors do have a GA button on the power levers which then command straight ahead and what ever is the best pitch for the GA.
The actual flying of the GA according to my mates who are now on jets is exactly the same apart from their auto throttle takes care of the power where as us TP drivers have to set it manually. The jet boys do say though that sometimes getting the full whack of power is more work than the manual setting of about 70-80% and asking the PNF to trim it if required.
So to get max power you need the props to be going as fast as possible and the torque to also be at max.
As for the go-around itself the aircraft with flight directors do have a GA button on the power levers which then command straight ahead and what ever is the best pitch for the GA.
The actual flying of the GA according to my mates who are now on jets is exactly the same apart from their auto throttle takes care of the power where as us TP drivers have to set it manually. The jet boys do say though that sometimes getting the full whack of power is more work than the manual setting of about 70-80% and asking the PNF to trim it if required.
Join Date: May 2001
Posts: 10,815
Likes: 0
Received 0 Likes
on
0 Posts
Aye true if they have dings in them it will cut your power transfer down.
Maybe you will know Dave but I was told that having the prop heat mats on also dropped their efficiency due to heating the boundary layer or some such.
Can't see it making that much difference myself and if it needs to be on, it needs to on.
Maybe you will know Dave but I was told that having the prop heat mats on also dropped their efficiency due to heating the boundary layer or some such.
Can't see it making that much difference myself and if it needs to be on, it needs to on.
Can't see it making that much difference myself
But the aerodynamic efficiency of a typical prop, as defined by work output (thrust x TAS) divided by work input (your torque x RPM value) is only about 80-85% max.
At least some of the Darts (only flew 542s) had a fuel trimmer system. You either used a chart or a whiz wheel and input the field elevation and temperature and came up with a percentage between 20 and 80. Set that number, move the condition level to CRUISE LOCKOUT and voila, you shove the power levers to the stops and the engines (shouldn't) overtemp.
