My 2 Cents:

I’ve been poking around in the air file with airwrench, and comparing the acft.cfg files. I’m a Flight Engineer by trade and have 5,000 hours flying USAF aircraft. I’m not a BUFF guy, but I slept at a Holiday Inn Express last night so this should be easy.

Conceptually, the mighty BUFF was created as a high altitude, long range, nuclear bomber. It performed admirably at this, but as the world changed, so did BUFFs missions. Over the last 50+ years it has been used (just to list a few) as a low altitude conventional penetrator, high and low altitude cruise missile delivery platform, and mainstay of the Manned Strategic Bomber portion of the (MSB) Single Integrated Operation Plan (SIOP). What do all of these roles have to do with the choice of high or low altitude performance? They all start out at high altitude, and the transition to the low altitude mission profile. I.E., A B-52C departs after a Klaxon en route on the assigned mission profile. They take off, climb, and maintain high altitude for the entire sortie. A B-52C departs after a Klaxon en route on the assigned mission profile. They take off, climb, and maintain high altitude up to the IP, then they descend to low level for mission execution, climbing back to high altitude for the trip home. Substitute a B-52H and these two scenarios are the same profiles flown today. In both cases, it’s the high altitude, not the low altitude that drove performance. The low altitude portion is simply considered a performance penalty similar to flying with a landing gear down, and the tanker schedule is adjusted as necessary.

Most simmers seem to fly high altitude long range as an MO. I have tried a few low-level routes with the CS B-52, and it is possible. The new radar works well but requires some creative interpretation to figure peaks and ranges. I still haven’t taken it to the Grand Canyon yet…

Wheeeew, ok, after that diatribe here is what I can see from a quick skim of the .cfg and.air currently supplied. All external numbers quoted are from 1B-52H-1 5DEC1982, and 1B-52H-1-1, 1JUN2006.

I have done a little bit of testing so far, here is what I have:

Takeoff Trials:
Computed: EPR=1.745, S1=125, S2=162, S2 Distance=7300 ft Minimum Runway Available= 8400ft, 18 Seconds from 70KIAS too S1 @ KJFK 22L (8400Ft):

Attempt 1: Abort at S1 (Using 1.74 EPR indicated)= Data Invalid. 1.74 EPR is 65% N2, basically flight idle.

Attempt 2: Abort at S1 (Artificially using 1.85 EPR, maximum for 25F)=Data Invalid, never reached 125 before running out of runway.

Attempt 3: Abort at S1 (Artificially using full throttle)= Data Invalid, Acellerated to S1, (125), aborted using idle thrust, drag chute, full spoilers and brakes. Departed runway at 70Knots.

Attempt 4: Abort at S1 (Artificially using full throttle)= Data Invalid, Accelerated to S1, (125), aborted using idle thrust, no drag chute, full spoilers and brakes. Departed runway at 55Knots. (Apparently the drag chute is only for show)

Attempt 5: 70Kt to S1 timing (Artificially using full throttle)=Data Indeterminate, time= 13 seconds, 5 seconds faster than predicted.

Attempt 6: 70Kt to S1 timing (Artificially using full throttle)=Data Indeterminate, time= 14 seconds, 4 seconds faster than predicted.

Attempt 7: S2 7300 foot unstick point (Artificially using full throttle)=Data Valid, unstick and liftoff occurred at about 7300 ft, albeit in a nose up attitude

I have yet to get the flaps in starting at 180Kts, and full up by 200. You have to almost go to idle after gear retract to keep from over speeding the flaps.

I have not done any climb, cruise or fuel trials yet.

Thrust:
Both in .air and .cfg, 30,000 lbs per pod is almost perfect. Charted thrust for the TF-33-P-3 (JT-3D) at standard day (Sea Level, 15C, 29.92) is 14,550lbs / engine, which is 29,100lbs/pod. 900lbs of thrust per pod X4 pods is a net difference of 3600 lbs of thrust, not enough to keep us over speeding so consistently. The absolute thrust could be tweaked a little, but that’s not the root. However; Takeoff EPR at KEDW (My preferred test base) was computed at 1.82, that setting was reached with the throttles at 12 o’clock (about ½ travel); from there until full throttle a maximum of 2.0 EPR was reached. There is an issue with the scalar (not the .cfg, the .air) somewhere that needs to be tweaked.

Drag:
I suspect that this may be a factor in the “over performance” but nothing jumped out at me from a quick scan, other than default values for tuning etc.

Weight:
A minor tweak, crew members should be 270lbs, not 170. Don’t forget all of the ancillary equipment that goes with each crew member. Heck, I weigh more than 170 nekked, and I’m in shape according to the USAF fitness regs. The current acft.cfg doesn’t allow for any weapons load. I would like to see stations for weapons added. The BUFF can only carry a full fuel load with no weapons. This was the result of the concept of carrying 1 or 2 nukes weighing a couple of thousand pounds each. When you pack on 70,000lbs of old fashioned iron headache, you must reduce the fuel load to compensate. This was a part of every B-52 mission planning phase, determining fuel loads, tanker points etc. How does this affect performance? See the next section, balance.

Balance:
The nose down climbing attitude of the B-52 is a well-established characteristic.  FSX is reporting a full-load CG of about  30% MAC, which is within limits of 22.9-35% MAC. Airwrench is reporting a 50.57% MAC for the same conditions. The visual model is performing as if it has a 50% MAC CG. The fuel tanks are currently not located realistically. I assume this is to keep it easy to fly; by locating the centroids so close together you essentially can’t run the CG out of limits. I am willing to bet the takeoff attitude will be corrected with a CG adjustment.

In light of this, here is my vote:

Make two .cfg and .air files available. Why?

The mighty and venerable BUFF is a handful when operated realistically, it requires a crew, much more so than a 777 or A340. Therefore, to keep a “Fun” model available the master set should be left alone, so that folks who don’t want to worry about fuel sequence and CG, wing flutter and bingo fuel prior to AR can fly a masterfully created model and enjoy it.

The second set should be added as a separate .cfg and .air for the realism craving airplane geeks like myself. I think it is safe to say that most of the enthusiasts out there would have no trouble swapping these two files.

--Dan