Geared engines and inflight operation?

[Tom-D]

Read back through this thread -- several other points were raised, and even agreed to by you.

Nice dodge.

Now answer the question.

 

[PPC1052]

How does this discussion apply to, say, a PT6A turbo prop with a reduction gear assembly? I presume the discussion about abrupt changes in throttle setting could similarly result in stress and failure of the planet/sun gears, true?

 

[poadeleted20]

Nice dodge.

Now answer the question.

Already did. :bye:

 

[OkieFlyer]

Henning, Tom, Ron, I'm going to kidnap all of you, throw you in a padded room together, and not let you go until you hug it out.


"Come on peope now, smile on your brother. Everybody get together. Try to love one another right now." -The Youngbloods-




That's right, a 32 year old ultra conservative redneck just quoted some hippie crap from the 60s.

 

[OkieFlyer]

FTFY.

but not all 175s swing the long prop, there is a version that has a constant speed prop.

Very true. The C model had the constant speed prop.

I suppose we shouldn't forget the P172D Skyhawk Powermatic.

 

[Tom-D]

Very true. The C model had the constant speed prop.

I suppose we shouldn't forget the P172D Skyhawk Powermatic.

That was described in "Cessna wings for the world" as the best 172 that the company ever built, and the natural carry on to the 172, with the IO360K, which became the XP.

 

[Pilawt]

That was described in "Cessna wings for the world" as the best 172 that the company ever built, and the natural carry on to the 172, with the IO360K, which became the XP.

The P172D (1963 model year only) was just a '62 175C with the 172's new "Omni-Vision" rear windows and cut-down rear fuselage, and wider-span horizontal tail. Only 65 were built.

The R172 series, built with the Continental IO-360 engine under the 175's type certificate, came along a few years later. The first iteration was the R172E sold to the US Army as the T-41B. Then in 1968 a civilianized version, the FR172E Reims Rocket, went into production at Reims, France. Finally a US-built version of the Reims Rocket, the R172K Hawk XP, was offered for the 1977 model year. R172/FR172 production in both France and USA ended after the 1981 model year.

The C-172RG Cutlass RG also was built under the 175's TC.

 

[Henning]

The P172D (1963 model year only) was just a '62 175C with the 172's new "Omni-Vision" rear windows and cut-down rear fuselage, and wider-span horizontal tail. Only 65 were built.

The R172 series, built with the Continental IO-360 engine under the 175's type certificate, came along a few years later. The first iteration was the R172E sold to the US Army as the T-41B. Then in 1968 a civilianized version, the FR172E Reims Rocket, went into production at Reims, France. Finally a US-built version of the Reims Rocket, the R172K Hawk XP, was offered for the 1977 model year. R172/FR172 production in both France and USA ended after the 1981 model year.

The C-172RG Cutlass RG also was built under the 175's TC.

Does the HaxkXP share the split cowl with the Cutlass?

 

[Pilawt]

Does the HaxkXP share the split cowl with the Cutlass?

I gather you mean the 172RG Cutlass RG (the fixed-gear 172Q Cutlass has the same cowl as the 160 hp 172P). No, they're completely different all the way back to the firewall. The 172RG firewall is a different shape, to support the retracting nose gear, and the cowl is three or four inches longer than the R172K's. 172RG cowl fits a 4-cylinder Lycoming and a nose wheel well, so it looks more bulbous on the bottom, with small cowl flaps on either side of the wheel well. R172K has a six-cylinder Continental, so the cowl is a bit higher and wider at the top, and there is a single, wider cowl flap just ahead of the nose gear strut.

I know the nose cap of the 172RG is split; not sure about the R172K offhand.

 

[Henning]

I gather you mean the 172RG Cutlass RG (the fixed-gear 172Q Cutlass has the same cowl as the 160 hp 172P). No, they're completely different all the way back to the firewall. The 172RG firewall is a different shape, to support the retracting nose gear, and the cowl is three or four inches longer than the R172K's. 172RG cowl fits a 4-cylinder Lycoming and a nose wheel well, so it looks more bulbous on the bottom, with small cowl flaps on either side of the wheel well. R172K has a six-cylinder Continental, so the cowl is a bit higher and wider at the top, and there is a single, wider cowl flap just ahead of the nose gear strut.

I know the nose cap of the 172RG is split; not sure about the R172K offhand.

Learn something new every day, I did not know that they called a FG version Cutlass, I thought they were all RG. I always loved that bonnet, made it so much easier to uncowl by yourself.

 

[N747JB]

How does this discussion apply to, say, a PT6A turbo prop with a reduction gear assembly? I presume the discussion about abrupt changes in throttle setting could similarly result in stress and failure of the planet/sun gears, true?

The PT-6 is a free shaft turbine, meaning the engine isn't mechanically attached to the prop. The engine drives the prop by forcing air across the gearbox, not by a drive shaft. You can start it and hold the prop with your hand, or so I'm told I've never seen the need to try it! There is a gearbox for the prop, but I've never heard of any damage from sudden power reductions.
I've owned a 421B and the engines are as reliable as any big bore Continental, and you fly them the same way, with care! I flew the 421 the same way I fly my 425 and my 182, push the power up slowly, reduce power slowly and plan my decents.

 

[flyingron]

That's not how the PT-6 works. It works by blowing the hot gases across a TURBINE (well two turbines actually) not the gears themselves. The latter wouldn't work very well. The thing that's different about the PT-6 is that the turbines that are connected to the gear box are not connected to the other turbines in the engine, hence you get the behavior sort of like an automatic transmission where you can rev the engine while standing on the brake.

Still once things are spinning, you're probably well advised not to abuse the gearing in the PT-6 just as with any other geared engine. Of course turbines don't have quite as fast throttle response (no matter how they're coupled) as piston engines, but I suspect you still don't want to go from driving the prop to having the prop drive the gears.

 

[RotorAndWing]

That's not how the PT-6 works. It works by blowing the hot gases across a TURBINE (well two turbines actually) not the gears themselves. The latter wouldn't work very well. The thing that's different about the PT-6 is that the turbines that are connected to the gear box are not connected to the other turbines in the engine, hence you get the behavior sort of like an automatic transmission where you can rev the engine while standing on the brake.

Still once things are spinning, you're probably well advised not to abuse the gearing in the PT-6 just as with any other geared engine. Of course turbines don't have quite as fast throttle response (no matter how they're coupled) as piston engines, but I suspect you still don't want to go from driving the prop to having the prop drive the gears.

I would say from experience that the Garrett's have equal if not better throttle response as a piston.

 

[Henning]

That's not how the PT-6 works. It works by blowing the hot gases across a TURBINE (well two turbines actually) not the gears themselves. The latter wouldn't work very well. The thing that's different about the PT-6 is that the turbines that are connected to the gear box are not connected to the other turbines in the engine, hence you get the behavior sort of like an automatic transmission where you can rev the engine while standing on the brake.

Still once things are spinning, you're probably well advised not to abuse the gearing in the PT-6 just as with any other geared engine. Of course turbines don't have quite as fast throttle response (no matter how they're coupled) as piston engines, but I suspect you still don't want to go from driving the prop to having the prop drive the gears.

The TPE-331 doesn't have any difference, it's not a free turbine, and it spools lickity split.

 

[Pilawt]

Learn something new every day, I did not know that they called a FG version Cutlass, I thought they were all RG.

Retractable 172RG ("Cutlass RG") built 1980-1985, 180 hp Lyc. O-360-F1A6 with constant-speed prop and 2650 lb MGW.

Fixed-gear 172Q ("Cutlass") built 1983-85, initially at the request of Embry-Riddle for use at its Prescott AZ facility. It's just a 172P with a 180 hp Lycoming O-360-A4N with fixed-pitch prop and 2550 lb MGW -- essentially a factory-built Air Plains or Penn Yan conversion. Slightly bigger carb air intake on the lower cowl is the only external feature distinguishing it from a 172P.