Ambassador Class

Universe :	Prime Timeline
Affiliation :	Federation
Class Name :	Ambassador Class [1]
Type :	Enhanced scientific/diplomatic explorer
Unit Run :	NCC 10521 USS Ambassador - Active NCC 1701-C USS Enterprise - Destroyed [1] NCC 26136 USS Zhukov [2] - Active NCC 26198 USS Valdemar [3] - Active NCC 26510 USS Yamaguchi [4] - Destroyed NCC 26513 [5] USS Exeter [6] - Active NCC 26517 USS Excalibur [7] - Active NCC 26632 [5] USS Gandhi [8] - Active NCC 26849 USS Adelphi [9] - Active NCC10532 [5] USS Horatio - Destroyed [10] plus 48 others built in total. 27 have been lost in all.
Commissioned :	2330 - 2357, class remains in service
Dimensions :	Length : 564 m [11] Beam : 338 m [12] Height : 132 m [13] Decks : 36
Mass :	2,350,000 metric tons
Crew :	550
Armament :	10 [14] x Type IX phaser arrays [14], total output 30,000 TeraWatts 2 x Type 1 burst fire photon torpedo tube with 250 rounds
Defence Systems :	Standard shield system, total capacity 2,025,000 TeraJoules Standard Duranium / Tritanium Double hull plus 7 cm High density armour. Standard level Structural Integrity Field
Warp Speeds (TNG scale) :	Normal Cruise : 6 Maximum Cruise : 8.8 Maximum Rated : 9.2 for 12 hours.
Strength Indices : (Galaxy class = 1,000)	Beam Firepower : 600 Torpedo Firepower : 700 Weapon Range and Accuracy : 860 Shield Strength : 750 Hull Armour : 800 Speed : 852 Combat Manoeuvrability : 2,500
Overall Strength Index :	723
Diplomatic Capability :	6
Expected Hull Life :	120
Refit Cycle :	Minor : 1 year Standard : 1 years Major : 25 years

Notes

During the 2320's the Ambassador class was developed as a replacement for the ageing Excelsior and Constellation classes as Starfleets front line Explorer type vessel [15]. Several innovative new features were included in the new design, most notably for the diplomatic and scientific missions. The USS Ambassador included high quality guest quarters and was equipped with elaborate conference facilities. Many of these areas were capable of maintaining a wide range of environments, a vital prerequisite for a vessel which would spend a great deal of its life dealing with non standard life forms. These facilities allowed her to host a much wider range of diplomatic functions than the more cramped Excelsior class, although it did lead to the class being dubbed "space hotels" in some quarters.

The scientific facilities of the Ambassador class were equally well equipped. The ships contained the most powerful space borne sensor arrays of their time, including eighteen modular sensor pallets for mission specific equipment. Twenty eight large dedicated laboratory facilities are included in the ship, along with facilities to convert three of the cargo bays to hold extra scientific equipment if necessary. This gave the Ambassador an estimated 450% increase in research capabilities over an Excelsior class vessel.

While the primary purpose of a starship is exploratory and scientific, the Ambassadors also have teeth. The class introduced phaser arrays to Starfleet in place of the ball turret phasers carried by previous designs. This measure greatly increased the ability of the Ambassador class to fire sustained bursts, and greatly reduced the recharge and cool down times. The use of an independent power system for every group of ten emitter segments in the array triples the survivability of the array compared to a ball turret, while there are also benefits to the reaction time, greater control of thermal effects, field halos and target impact. Overall the phaser arrays of the Ambassador are over 65% more effective than ball turrets of similar power. The concept of burst firing photon torpedoes was another first; although fitted with only two torpedo tubes, the Ambassador's ability to fire five torpedoes at a time from each tube effectively gave her ten tubes in place of two.

After the first batch of Ambassadors was delivered, Starfleet requested a series of modifications for the second batch. The USS Yamaguchi pioneered these changes. The engineering hulls aft end was widened to allow the shuttle bay to be enlarged, and a third shuttle bay was added to the underside of the engineering hull. This allowed the Yamaguchi to handle over 30% more shuttle craft than the standard Ambassador, making the ship more effective in colony establishment and support operations or emergency evacuation scenarios.

The siting of the Ambassadors saucer forward on the neck had led to some structural problems with early members of the class. Although these had largely been fixed by modifications to the structural integrity field, the changes had led to considerable complication of the layout of the ships connecting neck structures. Starfleet took the opportunity to shift the Yamaguchis saucer section back by six metres, allowing them to eliminate return to the original SIF modification without further difficulties. The nacelles were also shifted back in order to keep them at minimum safe distance from the saucer. The bussard collectors are a different model on the Yamaguchi, with a cap on the top and bottom of the inlet system which allows a less turbulent flow into the collectors, so increasing their efficiency by 12%.

The deflector dish was modified to allow more sensor systems to be installed, and to provide additional protection at high warp speeds. Additional sensor systems were installed in the main sensor dome on the saucer section, necessitating a housing to be installed between the dome and the hull to hold the extra equipment. This allowed the sensor range and sensitivity to be increased by over 20% compared to the original Ambassador. The layout of lifeboats within the saucer section was also modified to allow increased evacuation speed in an emergency.

Perhaps the most important change was the installation of a new model of impulse engine. The original Ambassadors had always been considered to have low speed and agility at impulse and the new engines provided almost 30% greater thrust, largely correcting this problem. The only exterior change caused by this alteration is that the engine exhaust is red rather than blue.

The Yamaguchi subtype proved highly successful in service, and all existing vessels began to upgrade to this standard from 2350. The only ship which was not so refitted was the USS Enterprise-C, which was destroyed in 2346 while defending a Klingon outpost from attack by the Romulans. The action secured peace between the Federation and the Klingon Empire. [1] The ships destruction came some six months before it was due to return to Spacedock for modification.

The USS Ambassador was launched in 2330 and commissioned in 2332. Series production continued at a slow but steady pace until 2357, when the sixty eighth vessel was launched. Production was then suspended in favour of the new Galaxy class.

Colour key

References

#	Series	Season	Source	Comment
1	TNG	3	Yesterday's Enterprise
2	TNG	4	Data's Day
3	DS9	2	Tribunal
4	DS9	1	Emissary
5			Star Trek Encyclopedia
6	VOY	2	Non Sequitur
7	TNG	5	Redemption, Part 2
8	TNG	6	Second Chances
9	TNG	3	Tin Man
10	TNG	1	Conspiracy
11			Star Trek Encyclopedia	3rd Edition, calculated from scale diagram on Page 686 using 641 m Galaxy class as a referant
12			Star Trek Encyclopedia	3rd Edition, calculated from scale diagram on Page 686 using 641 m Galaxy class as a referant (assuming circular saucer)
13			Star Trek Encyclopedia	3rd Edition, calculated from scale diagram on Page 686 using 641 m Galaxy class as a referant
14			Visible on the shooting model
15			Star Trek The Next Generation Technical Manual	Page 1

Comments

The Ambassador isn't my favourite of ships. I can see that she needed to be a stepping stone between the Excelsior and the Galaxy, but I think she came out just plain ugly. However, the Enterprise-C was an Ambassador and it's the unwritten rule of Trek that every Enterprise must be the best! So I made her a big step forward from the Excelsior in almost every way. The class name makes me think that she was mostly designed for non combat, so I emphasized her diplomatic and scientific capability as much as I could. The ships phasers as seen in "Yesterday's Enterprise" are very short phaser arrays, so I decided to say that the Ambassador pioneered these weapons, as well as the burst fire torpedo tube.

It's not all that clear just what advantages phaser arrays have over phaser banks; at first I thought an array was like hundreds of old style banks joined together, giving hundreds of times the overall firepower. However, if that was the case then phaser arrays should be as long as possible - the ideal weapon would be one gigantic phaser array that went all around the ship! But the trend these days seems to be for larger numbers of smaller arrays, which contradicts this idea. So I've tried to think up realistic advantages to be gained from using phaser arrays; many thanks to the members of rec.arts.startrek.tech for their rather lengthy debate on this issue, which provided a great deal of help in this area.

One problem with the Ambassador is their relative rarity. Starfleet generally seems to use today's super ships as tomorrow's workhorse, so really we should see lots of Ambassadors out there - but we don't. My guess is that the ship has been phased out by the Galaxy/Nebula combination, with the Galaxy as super ship and the Nebula as workhorse. I suppose that Starfleet might also have experienced some problems with such an innovative design and been forced to retire most of the ships early, though I'm reluctant to say that any Enterprise might have suffered from such problems.

As with many ship classes, we know remarkably little about the Ambassadors. Yet I can't possibly believe that a 24th century databank wouldn't know details such as the size, mass, number in service, etc. Hence, I've been forced to speculate a lot here.

All the images are taken from "Yesterday's Enterprise", which as far as I know is the only time we've seen any good close-up views of the Ambassador. However, this leads to something of a problem. Rumour has it that the Enterprise-C model was broken somehow after the episode was made - I don't know how, somebody may have dropped it or it may just be that the battle damage put on for the show made it unusable. Whatever the reason, the makers built a new version of the Ambassador which was used for all future appearances of the ship. And this new version was significantly different. The first appearance was as the USS Yamaguchi in the DS9 pilot episode "Emissary". Compared to the Enterprise-C there are many small changes : The Yamaguchis saucer section and nacelles are shifted back by about 6 metres. The Yamaguchis deflector dish has a darker spot of some sort in the middle of it. The lifeboats have been re-arranged on the saucer section. The Yamaguchis sensor dome sits on another structure which is absent from the Enterprise-C. The Yamaguchi has a cap on top of and beneath the bussard collectors. The Yamaguchi has a third shuttle bay located on the 'overhang' at the back of the Engineering hull. The aft end of the Yamaguchis engineering hull is broader. The Enterprise C's impulse engines glowed blue, the Yamaguchis glowed red.

The Ex Astris Scientia site is responsible for spotting these changes, and has an excellent article on the different variants of the Ambassador. You can access it via the links page of this site.

Explaining the Yamaguchi variant is the thrust of some of the notes on my own entry for the ship.

Page views : 181,997

Last updated : 29 Mar 2014

Series :	TNG Season 3
Episode :	Yesterday's Enterprise

Series :	TNG Season 4
Episode :	Data's Day

Series :	DS9 Season 2
Episode :	Tribunal

Series :	DS9 Season 1
Episode :	Emissary

Series :	VOY Season 2
Episode :	Non Sequitur

Book :	Star Trek Encyclopedia
Comment :	3rd Edition, calculated from scale diagram on Page 686 using 641 m Galaxy class as a referant