How long should the engines last?

[TheFinn88 13]

The rule is good, the BMEP indicators are better and way more easier.  Just keep a positive reading on your BMEP instruments (over 60) and you'll be fine. For descending, I keep my BMEP readings between 80 and 100. That's a setting of about 25" @ 2250RPM. 

[downscc 1,327]

Good topic... descents require planning.  Not at all like waiting for TOD based on some distance rule of thumb, but you actually should be calculating time distance and speed even if only in your head.  A good example was my recent trip in the C118 from Lake Tahoe KTVL to Montery KMRY.  Tahoe is on the edge of a 6000 ft elevation lake surrounded by mountains and Montery on Southwest about an hour on the coast.  Departure requires a climb above 11000 to clear the mountains, and I climbed to 12500 in VMC conditions. Once over the central valley, it is time to start a 500 fpm descent and that put me at just over 3500 ft crossing Salinas SNS with enough room to slow down, get dirty and land on the LOC28L.  In summary, this flight is essentially one constant descent.  It is also very beautiful with Orbx and AS16, and a basic familiarity with the area (I got my PPL in Sacramento in 1975).

[metzgergva 28]

If you run the engines at 2000 rpm your manifold ptressure should be above 20 in. If you fly 130 kts with that setting it is fine. If you do a descent with 200 kts you should add a bit more MAP, like 22 in.

All this to avoid that the airflow will drive the prop to drive the engines with not enough power from lack of throttle position. 

[PMSoares 7]

On ‎10‎/‎17‎/‎2017 at 7:20 PM, metzgergva said:

If you run the engines at 2000 rpm your manifold ptressure should be above 20 in. If you fly 130 kts with that setting it is fine. If you do a descent with 200 kts you should add a bit more MAP, like 22 in.

All this to avoid that the airflow will drive the prop to drive the engines with not enough power from lack of throttle position. 

Alexander... I have noted that the plane is quite difficult to slow down to max flap speed (174 kt) from speeds above 220/230 knots with power settings at 25/2050. Sometimes it requires more thn 15 Nm in level flight to slow down from 230 to 174 in order to select flaps 20. Is the real DC-6 that hard to decelerate? Is it acceptable to reduce the RPM to, let's say, 1800 RPM in order to help it to lose speed more quickly? 

[RonnieDuck 10]

2050 RPM reduce more drag than 1800RPM due to the prop pitch!

[TheFinn88 13]

5 hours ago, RonnieDuck said:

2050 RPM reduce more drag than 1800RPM due to the prop pitch!

I can confirm that from my experience. Higher RPM equals to more drag, which results in faster deceleration. One part of the before landing checklist is to set the props to 2400 RPM. You could do this step earlier than on final approach to slow the Six down. But you have to keep an eye on the BMEP gauges and your throttle settings when increasing RPM, as the BMEP will drop quite a bit. So you might have to add a more power to stay in positive range. But it will still help you to slow down a little bit faster. A RPM setting of 1800 will make you even faster in descent, as there is less drag from the props. Proper descent-planning in the Six is crucial. I mostly use the TOD calculator of the GTN650, works pretty well with a programmed descent rate of 500 FPM. And I always try to go for the lowest possible altitude on a STAR. Once I had to tell a VATSIM-ATC that my descent rate is limited to 500 FPM, after I called for an early descent and he thought that it is way too early. I think I have to add an additional RMK to the flight-plan.

[metzgergva 28]

First rule is to keep the engine settings as described. Going down to 1800/20 is a valid procedure and good if you are light to slow down. 

RW pilots said that they calculate 10 NM to slow down from 200 to 175 in level flight approaching the airport. If you take that into your decent calculation you are fine.

Typical decent rates in cruise are 300 ft/min and max 500 ft/min. If you want to fly an ILS (todays procedure not in the 50s) you need to slow down to 110 kts and be configured with gear down and flaps 30 to maintain speed on the glide and have 500 ft/min descent rate. Final slow down by applying flaps down to full for landing.

[TheFinn88 13]

21 hours ago, metzgergva said:

RW pilots said that they calculate 10 NM to slow down from 200 to 175 in level flight approaching the airport. If you take that into your decent calculation you are fine..

Interesting to read that part, because from my experience in the sim, I ended up calculating 5 to 10 NM level flight before the IAF for slowing down from about 200 to 175 KIAS. Thats why I always use the lowest possible altitudes on STARs, so I end up getting some level-flight sections. And as soon my KIAS drops below 175, I drop the flaps to 20°. Because in many flights I've ended up way too high and too fast on approach after waiting for too long with dropping flaps and gear. And when the ATC messes up my calculated descent-profile, I mess up his traffic flow by requesting a hold to slow down.

[metzgergva 28]

When we fly first times with our DC-3 into GVA we messed up the approach every time and we are 80 in the glide. Now ATC knows the plane and typical gives us radar vector in parallel and low or a short visual, but still then it happen that we have 3-5 five waiting for departure...