G-IV and G-IV/SP differences
For inquiring minds - G-IV and G-IV/SP differences
s/n 1000 to s/n 1213 are G-IV
s/n 1214 starts G-IV/SP
73,600 lbs AUGW vs 75,000 lbs AUGW (1,400 lbs)
73,200 lbs MTOW vs 74,600 lbs MTOW
- all Gulfstreams are 400 lbs taxi fuel
58,500 lbs Max Landing vs 66,000 lbs Max Landing
Va of 170 KIAS vs Va of 206 KIAS (Max Maneuvering Speed)
All other speeds limitations are identical.
SPZ-8000 FMS vs SPZ-8400 FMS
SPZ-8400 FMS introduces some real niceties for the crew - selectable DH or MDA on the PFDs with alerting, vastly better and truly usable GPWS terrain display on the PFDs, but otherwise are pretty much the same. Same software version numbers for each. ASC-190 typically aircraft remain SPZ-8000 aircraft; the ASC does not involve the SPZ (except for the perf computer)
G-IV BBW Brake-by-Wire (absolutely horrible) vs /SP HMAB (Hydro-Mechanical Analog Braking) (smooth)
- just the difference in braking is almost worth the difference in price bewteen -IV and /SP
G-IV thrust reverser use limited to 1 minute in 30 minutes vs no restriction on /SP.
- open T/Rs heat up the solenoids, lots of failures
- ASC-166 available to mod straight G-IV
Terminology - Gulfstream uses Aircraft Service Changes instead of Service Bulletins, etc.
ASC-190 modifies G-IV to G-IV/SP weights and performance.
- thus there are G-IV's, G-IV/SP's and G-IV ASC-190 a/c - you cannot visually tell them apart. No s/n change, no -dash modifiers, no suffixes, no logos. You have to read the logbooks for ASC-190.
- (actually, on US a/c, check the left side of the tail cone for the TSA required s/n plate, then look at the MLG wheels - different # of slots and rim diameter on the higher gross weight a/c)
Virtually everything /SP is retrofittable to base G-IV through ASC kits if you can afford the dollars and the downtime. ASC-190 is the biggie among ASC's.
G-IV/SP and ASC-190 aircraft have published shorter landing differences because they get official FAA Flight Manual Performance Section credit for automatic ground spoiler deployment on landing. The auto deployment system is essentially the same on G-II, G-III, G-IV, ASC-190, and G-IV/SP aircraft, but only the /SP gets to move the not-legal-for-planning-purposes demonstrated performance pages out of the manufacturers handbook and into the offically sanctioned Flight Manual. There is no real world performance difference. However, in an FAA paperwork world, it becomes important to a -135 charter operator, and for the -91 operator, it "legalizes" what the aircraft can actually do vis-a-vis runway requirements.
The /SP is unique in that it can be operated in two Instrument Approach Categories, Category C or Category D, via an ASC that consists of a reversible placard in a little clear plastic holder for the cockpit and a Flight Manual page insert. You can depart and operate at /SP weights with the placard turned to 66,000 lb MLW, and after burning enough fuel to reduce your landing weight to 58,500 lbs or less, you turn the placard the other way round and become a straight G-IV for approach category purposes. An /SP or ASC-190 aircraft cannot conduct an IFR approach into the ever popular Aspen, Colorado (Approach Categories A,B,C, but no D), but at a Landing Weight of 58,500 lbs or less with the ASC placard installed and turned the right way, they legally may! Not suprising, it's referred to as the Aspen ASC.
(I'm told, this came about because the straight G-IV was delivered at the 58,500 lb Max Landing Weight, and so all the performance data was developed during initial certification of the aircraft.)
Fuel capacities, ranges, speeds, operational altitudes at weight for weight are the same for each variant, though purists like to argue that the straight G-IV is fractionally lighter and so may be a knot or two faster. I have several thousand hours in the beasts and wouldn't take that bet. One cycle through paint and interior and avionics fattens up a lean straight G-IV nicely.
Mmo is .85. Normal Cruise is .80 (460 Kts) in the 40's. Hi-speed cruise is .82, though .83 is do-able if you like the low 30's for flight levels. You need a compelling reason to slow below .80; endurance only really. The difference between KTEB to KVNY (2412 nm) at .82 vs .80 is 20 minutes and 2000 lbs of fuel. At an ISA +10 atmosphere and AUGW take-off, you can go straight to FL380, then FL400 30 minutes later. FL450 is max, and either versions are happy at FL430 or FL450. Climb is 300 KIAS to .75, or 320 and .78 if needed. Descent is Mmo to 300 KIAS, then hold that to 10,000 feet.
Teterboro to Paris is common, and the reverse is okay if hold times aren't excessive. I've done Minneapolis - Hilo many times with legit PSR and landing reserves. (No old bold pilot here!)
Do not sell the G-IV vs /SP weight differences short. I frequently captained both a straight G-IV and a G-IV/SP out of Tokyo. Both aircraft could make the flight from Tokyo to Honolulu non-stop, but in the straight G-IV you could not take passengers with you. One thousand four hundred lbs difference in carrying capacity equals 8 passengers at the FAA's standard 170 lbs, or 6 passengers and their baggage at our Charter Op Spec weight of 210 lbs per passenger. I had actual weights on our Japanese passengers and their luggage, and 1400 lbs amounted to 11 passengers!
If the end user is purely regional or domestic, a straight G-IV is great. If you are going max range or wish or need to tanker fuel frequently, the ASC-190 option or the G-IV/SP becomes the more desirable aircraft.
Please feel free to correct any error here.