How realistic is it?

[DC3]

Here's a direct quote from FSAviator's tutorial for Stratocruiser.

If we departed at 147,000 pounds then burning those 23,000lbs of fuel at 3200 PPH will take more than seven hours. It is possible to accelerate a B377 to 264 KTAS using cruise power, but in average weather it will take more than seven hours of skilful step climbing. Of course if we depart at 124,000lbs we could get up to FL250 and accelerate skillfully to 264 KTAS (in average weather) in under 50 minutes, but we will never make a profit, or win a war, carrying almost no payload.

All KIAS assume standard conditions at the given flight level

264 KTAS = 190 KIAS @ FL210
264 KTAS = 192 KIAS @ FL200

264 KTAS = 168 KIAS @ FL250

In all case with no headwind or tailwind it is equivalent to 264 kts across the ground.

[Cormack]

I've just made another experiment and with maximum permittable weight on start I was able to easily climb to FL160 in 37 minutes and i was with 140.700 lbs of weight while doing so (36.900 lbs of fuel alone). My attitude indicator showed 3 degrees up and dropped to 2 degrees after about 2 minutes. All in all, in about 5 minutes I was able to reach 180 KIAS and 1 degree up pitch. And about 7 minutes after, 185 KIAS and no degree either way. After waiting another minute, it reached 189 KIAS.

Correct me if I'm doing something wrong. During cruise I am holding 38 in MAP and 1700 RPM, while for climb I am changing it to 45 MAP and 2350 MAP, rejecting climb before KIAS reaches 165 KIAS, as was stated in the handling notes from Cal Classic site.

At 140.200 lbs of weight I have began my second altitude change to FL180 and reached it after 49 minutes since I've departed. I was flying at 164 KIAS upon reaching FL180. This raised to KIAS 173 in about 3 minutes. After 6 minutes since altitude at FL180 hold I reached 186 KIAS. My weight was 139.500 lbs, fuel 15.760 lbs. Not a single degree in pitch.

As to weather conditions I had headwind of about 11 kts and right Xwind of about 62 kts. Mag. Heading 245.

I reached FL200 after 59 minutes, weight 139.000 lbs, fuel 35.280 lbs, at the moment of setting altitude hold I had 163 KIAS. After about 2 minutes I had 170 KIAS. Pitch 2 degrees up after 2 minutes. "Live engineer" AI set turbos to 61%.

4 minutes later - 180 KIAS, not a single degree pitch either way. I've noticed that I was setting MAP to 35,5 - 36 in, not 38 all the time. I will set it to 38 in from now on.

Anyway, after 1hr5mins I've reached 192 KIAS and began transition to FL220. Reached it 1 hr 9 or 10 mins from the start. Pitch 2 degrees up, weight 138.100 lbs, fuel 34.330 lbs. Turbos at 67 percent, turbo temp - 122 degrees celcius.

Reached 185 KIAS after 1hr 13 mins since the start. 190 KIAS a minute later. Turbos were still at 67%.

After 190 KIAS I began to change my altitude to FL240, I won't go any higher. Stopped at FL230 as my KIAS dropped to 167. Reached FL230 at 1hr 17 mins since the start.

Then again, I reached KIAS 190 at 1 hr 20 mins since the start and started to move to FL240. I reached FL240 at 1 hr 23 minutes from the start. My weight was 136.900 lbs, fuel 33260 lbs. Distance traveled - 320 nm, attitude indicator showed not a single degree, free air temp -25 degrees celcius, turbo at 74%, turbo temp - 104 degrees, engine temp 201 degrees. At 1700 RPM and about 36 MAP I am able to maintain speed of about 180 KIAS.

Doesn't it seem excessive that I managed to get to FL240 in as little as 1 hr and 23 minutes, when in real life it was supposed to take hours?

[Cormack]

Perhaps someone who knows better could help me by analysing data I've provided to find any mistakes?

Mainly, perhaps that I am setting auto lean only after reaching my final altitude of FL240/250 is responsible for too fast climb?

[FAC257]

This doesn't answer any question directly, but I just ran a "by the manual" climb to 30K. Straight to altitude, without stepping on the way up.

Took off with 72 passengers at a TOW of 147,000 lbs. The text in red are my actual numbers compared to the manual (page 94).


I was flying almost directly against the wind on the way up and by the time I reached 30K, she was fighting a 50kt headwind. I think that may account for the extra miles.


I tend to only watch two numbers on a climb. The IAS and the Torque Pressure. 170KIAS @ 197PSI

IAS:
I don't let the IAS drop below 170 KIAS. That tends to be the trigger level for high carb temps in warmer air and from what I remember, that was the number we went by during testing. It also seems to be the fine line airspeed between wallowing versus accelerating nicely, after leveling off at cruise altitude.

Torque Pressure:
Whether I'm climbing or at altitude, this is the engine parameter I go with. During a climb - max 197PSI. Once at cruise altitude - max 168PSI.

This formula has been giving me pretty consistent costs per mile under 90 cents. My last flight was a 9:45 long flight, 72 passengers, MTOW at 80 cents.

[DC3]

I have some Boeing charts done by Boeing engineers in 1946 that show with 4 engines at 2650 BHP and a weight of 140,000 lbs the B377 required 35 minutes to climb to 25,000 ft (ave 715 fpm). The climb velocity was 190 mph (165 kts) and fuel use was approximately 4400 lbs at (126 lbs/min). Distance traveled was approximately 136 miles. This was all on a standard day.

The B377 is capable of achieving the climb you describe.

One thing to realize is the B377 could actually climb a little better than it's contemporaries so it was able to get to altitude quicker. Also, climb restrictions by airlines more often were dictated by babying the engines to reduce maintenance costs. The dictates of the airlines didn't necessarily match IAS targets. In the case of the B377 torque targets were more likely to be the specified limiter as well as engine temp limits.

I have collected some original Boeing data which matches the performance of the A2A B377 pretty closely.

If you search these forums you can find the same info.

PM me and I will email the pdfs to you.

[Scott - A2A]

I have some Boeing charts done by Boeing engineers in 1946 that show with 4 engines at 2650 BHP and a weight of 140,000 lbs the B377 required 35 minutes to climb to 25,000 ft (ave 715 fpm). The climb velocity was 190 mph (165 kts) and fuel use was approximately 4400 lbs at (126 lbs/min). Distance traveled was approximately 136 miles. This was all on a standard day.

....I have collected some original Boeing data which matches the performance of the A2A B377 pretty closely.

Bingo and thanks for posting this, as we designed this aircraft's performance using the manuals. If someone is going to post some other numbers that contradict the manual performance sections, there are just way too many variables that we don't know about (can't know about) that affect performance.

Flight testing is a very delicate operation that can be completely messed up with the smallest factors. Even large factors can play a part. For example, as far as we know, the superchargers or turbochargers were modified, or some aerodynamic changes or made, etc. So we made a conscious decision to make the Accu-Sim 377 by the book where flight testing was professionally done.

Also, as Cody said, Tim Choppe of the Berlin Airlift who is restoring a C97 has been flying our 377 almost daily, for many years now. Tim as as capable and meticulous as any pilot in existence and in all of this time, after many hours of discussion, performance has never been raised as an issue.

Scott.

[DC3]

On the forums here are the documents related to rw ops of B377
http://a2asimulations.com/forum/viewtop ... 67&start=0

[Cormack]

What about FSAviator's operational ceiling rules? Are those entirely untrue?

Also, it seems that I was able to reach Hawaii in 8 hrs 30 mins, which is very close to the real-life 8 hrs 45 mins schedule. I wonder, how could PAA pilots stick to the timetable if they were flying at 10.000 feet or so, where the ground speed is entirely different?

[Scott - A2A]

Cormack,

I am not familiar with what fsaviator does - they are just not on our radar. The only things we look at when developing an airplane is:
- The physical aircraft
- Our first hand testing and experiences
- POH and Maintenance manuals

So if there is something you think that may be wrong with the flight model, we need to refer to actual flight manuals for either the 377 or C97. And if you find something, we will always look into it. And also, thanks ahead of time for your posting and interest in our products and making them better.

Scott.

[DC3]

What about FSAviator's operational ceiling rules? Are those entirely untrue?

Also, it seems that I was able to reach Hawaii in 8 hrs 30 mins, which is very close to the real-life 8 hrs 45 mins schedule. I wonder, how could PAA pilots stick to the timetable if they were flying at 10.000 feet or so, where the ground speed is entirely different?

According to this Pan Am schedule actual flight time was 9 hours 35 minutes between SFO and Honolulu.
http://www.timetableimages.com/ttimages ... 0/pa50.pdf

The distance from SFO to Hawaii according to skyvector.com is 2082.4 nm, which I will round to 2300 on general principle.
To travel that distance in 9h35m requires an average ground speed of 240 kts. This would also be the average TAS without any tail or head wind component.
At 10,000 ft on a standard day this is equal to 206 kias.

For a takeoff weight of 140,000 lbs:
Set RPM to 2100 and Torque to 165 PSI and the B377 will cruise to Hawaii at around 206 KIAS burning a little more than 3500 pph of fuel. (set mixture to lean)
This is by the book and the COTS B377 will come pretty close to this. (Book specs are predicated on new engines, good piloting, weather conditions, etc.)
Total fuel burn will be approximately 34,000 lbs. If fuel burn is 4,000 lbs per hour the total burn will be approximately 38,000 lbs.
At 134,000 lbs enough fuel can be carried plus 45 passengers to make it from SFO to Hawaii.
At 140,000 lbs a full load of passengers can be carried.

As an aside the skyvector.com website is showing tailwinds today from SFO to Hawaii at 10,000 ft. This is unusual for a west to east flight.

I personally like the calclassic.com web site and have read the fsaviator information. My comment about the fsaviator information is some of it is good and some of it should be questioned by the reader. In the study of history it is always better to go to the original source material. I would recommend that course f action in reply to all the questions you have about the B377. FSAviator is not a primary source whereas there is a lot of primary source material available on the web. The material used by A2A to create their flight model is primary source material.

I think the A2A B377 and the primary source material will produce good questions to ask on the calclassic sight, which I have noticed that you have done.

[Scott - A2A]

Cormack,

I read some of your posts on other forums, and you seem to be needlessly beating yourself up.

The site admin even told you that he has little flight information on the Stratocruiser, yet you seem to hold anything this guy says higher than actual independent flight tests from Boeing and the U.S. Military. You have access to the real flight manuals. Use them, that is what they are for. If someone else's simulated aircraft is not climbing as well as the manual indicates, then their flight model is probably wrong.

Also, remember, the 377 is turbosupercharged. They designed it this way because turbochargers are far more efficient than multiple stage superchargers. As long as temperatures are OK, turbocharged aircraft climb strongly all the way to very high altitudes. It's supercharged-only airplanes that tend have more difficulty at very high altitudes.

Scott.

[Emil Petecki]

Transocean Air Lines Flight Operations Manual for B-377 states:

Climb

(1) Normal climb speed is 170 IAS, 2400 BHP (2350 RPM, 238 TOP)
(2) In order to facilitate control of cylinder head temperatures under high outside air temperature conditions, increase climb speed to 185 or 190 IAS. The increase in time required to reach cruising altitude will for the most part be compensated for by the increase in distance covered during the climb.
(3) The cowl flaps should be set to 225 deg CHT up until 3" CFG is reached. Maximum continuous CHT at normal climb power is 232 deg C. Maintain CAT as desired. Turbo-superchargers should be utilized to maintain power for climbs to initial cruising altitudes.
Observe 1.5" minimum CFG in climb to allow CHY below 225 when possible.
(4) TBS override switches to "Climb & Cruise". Monitor EBP gages for no rise.
(5) Apply turbos when required and adjust calibrator pots to maintain 238 TOP. Rate of TBS application should be such as to avoid cabin pressure surges. Observe cabin R/C. Open intercoolers as required.
(6) Air conditioning "As required".
(7) #3 Inverter "To lighting bus"
(8) En route climb
Spark advance "Take off & Climb"
Mixture Control "Auto Rich"
Cowl, oil and Intercooler flaps - "set"

Maximum performance
(1) Maximum performance climb configuration immediately after take-off is V2 speed for gross weight of aircraft, maximum power, gear up and flaps 25 deg.
(2) When clear of obstructions accelerate in the climb and retract flaps same as normal.
(3) Continue acceleration to and maintain 160 IAS with METO power.

Unbalanced power
(1) When an engine fails, the normal feathering procedure will be accomplished as outlined in Emergency Check List. Where feathering an engine is required, take the time necessary to definitely identify the inoperative engine and the corresponding feather button or switch. A slight delay in feathering is more desirable than feathering an operating engine with the malfunctioning engine still windmilling.
(2) Adjust power on the remaining engines if necessary to climb to and maintain the desired altitude consistent with gross weight and terrain clearance. Do not use altitudes higher than required due to excess power required, higher fuel consumption and increased wear and tear on the remaining engines.

Normal cruise
(1) To establish cruise, the instant the desired altitude is reached apply sufficient forward elevator to stop the altimeter. Maintain climb power until increased airspeed has caused desired engine cooling and the approximate cruising airspeed has been reached, then reduce to cruise power. Trim aircraft as required.
(2) Establish in accordance with Cruise Control Manual - DO NOT EXCEED MAXIMUM CRUISE POWER LIMITS.
(3) Except for weather or traffic consideration, avoid operation at altitudes too high for best true airspeed. The speed loss of a "slow" airplane will be magnified by attempts to operate too high and the airplane will be less stable and more difficult to trim. When high temperatures give an excessive density altitude performance will be improved by descending.
(4) Set desired cruising power
Adjust throttle (full open if possible) RPM & TBS for desired BHP and approximately 221 TOP.
Adjust cowl, intercooler and oil cooler flaps to approximate desired settings. Set intercooler flaps by opening beyond that required then close gradually until CAT rise is detected. Open slightly to recover rise.
Determine and set lean best power point with mixture control using primer if necessary.
Readjust calibrator pot and/or throttle for 221 TOP.
Lean out mixture control to 206 TOP.
Set spark advance to Cruise (Check pattern shift individually on analyzer)
Lean mixtures further to re-establish 206 TOP. Check for proper fuel flow.
For normal operation use Rear Fuel Boost Pumps outbound and Front Pumps inbouns to main base.
Sweep analyzer ignitoon patterns every hour.
Record instrument readings at least once every two hours.

Turbulent air
(1) Before encountering turbulent air, the airspeed must be reduced to a speed range of 165 to 190 IAS.
(2) In view of the fact that the airplane is more capable of withstanding a severe gust with the flaps retracted, it is recommended that the airplane be operated in turbulent air with the flaps and gear retracted at the above recommended airspeeds.
(3) The design load factors used in transport category aircraft are based on the premise the pilots will use good judgement in the avoidance of areas of severe turbulence and will handle the aircraft in such a manner as to avoid inducing large maneuvering loads by abrupt and excessive control movements.
(4) Barometric instruments can give false readings due to rapid changes in pressure encountered in a thunderstorm thereby indicating greater changes in altitude than actual. False readings are also cause by high wind velocities in mountainous terrain.
(5) Heavy rain or hail may reduce indicated airspeed readings considerably by partial blocking of the pitot tubes.

Hope that helps!

[DC3]

I thought I would try flying from ksfo to phnl at 10,000 ft to see what time it would take. I had a crosswind with a tailwind component much of the way. It should be noted this is unusual for the ksfo to phnl flight. One of the reasons for flying lower was to minimize the typical headwinds which were much stronger at higher altitudes.

My final flight mileage was 2397 sm over the ground and 2447 sm through the air, i.e. I overflew phnl and turned back for a straight in on 40R.
My flight time was 8h 53m with a tailwind. This was a little quicker than the scheduled 9h 35m. My passengers were happy about this as they could hit the beach earlier.
Average ground speed 275 mph.

2397 sm = 2084 nm 2447 sm = 2127 nm 275 mph = 239 kts

The initial climb to 10,000 ft was made at 170 kias and lasted a bit less than 20 minutes

Flight was made with 65 passengers and a full fuel load 46,740 lbs. Total fuel burn was 38,688 lbs equal to 4355 lbs/hr. Actual cruise burn was 4000 lbs/hr @ 160 psi torque on each engine.
RPM was set at 2100 during cruise.

Takeoff weight was 146,879 lbs. My engine condition at the end of the flight was Good, Fair, Good, Good, for 1,2,3,&4 respectively.