View source for Delta III

{{short description|Space launch vehicle}}
{{about|the rocket|the submarine|Delta III-class submarine}}
{{Infobox rocket
|name           = Delta III
|logo           = Delta logo.png
|logo_upright   = 0.3
|image          = Delta III.svg
|upright        = 0.4
|caption        = Delta III rocket diagram
|function       = Orbital [[launch vehicle]]
|manufacturer   = {{Unbulleted indent list
   | [[Boeing]] (design, manufacturing and assembly)
   | [[Mitsubishi Heavy Industries]] (RP-1 tank and upper stage manufacturing)
   | [[NASDA]] (upper stage design)
   | [[Beyond Gravity|Contraves]]/[[European Space Agency|ESA]] (fairing and payload adapters)
   }}
|country-origin = United States

|height         = {{cvt|35|m|ft}}
|diameter       = {{cvt|4|m|ft}}
|mass           = {{cvt|301,450|kg|lb}}
|stages         = 2 or 3
|capacities     = 
  {{Infobox rocket/payload
  |location =  [[Low Earth orbit|LEO]]
  |kilos    =  {{cvt|8,290|kg}}<ref name="Datasheet" />
  }}
  {{Infobox rocket/payload
  |location =  [[Geostationary transfer orbit|GTO]]
  |kilos    =  {{cvt|3,810|kg}}<ref name="Datasheet" />
  }}

|family         = [[Delta (rocket family)|Delta]]
|status         = Retired
|sites          = [[Cape Canaveral Air Force Station|Cape Canaveral]], [[Cape Canaveral Air Force Station Space Launch Complex 17|SLC-17B]]
|launches       = 3
|success        = 0
|fail           = 2
|partial        = 1
|first          = 26 August 1998
|last           = 23 August 2000
|stagedata      = 
  {{Infobox rocket/stage
  |name       = [[Graphite-Epoxy Motor|GEM 46]]
  |type       = booster
  |number     = 9
  |solid      = yes
  |thrust     = {{cvt|628.3|kN}}
  |SI         = {{convert|273|isp}}
  |burntime   = 75 seconds
  |fuel       = [[Ammonium perchlorate composite propellant|AP]] / [[Hydroxyl-terminated polybutadiene|HTPB]] / [[Aluminium|Al]]
  }}
  {{Infobox rocket/stage
  |type       = stage
  |diff       = <!--variant of rocket this is used on, optional-->
  |stageno    = First
  |name       = <!--name of the stage/booster, optional-->
  |engines    = 1 × [[RS-27A]]
  |thrust     = {{cvt|1085.79|kN}}
  |SI         = {{convert|254|isp}}
  |burntime   = 260 seconds<ref name=d3ppg>{{cite web|url=http://www.boeing.com/defense-space/space/delta/docs/DELTA_III_PPG_2000.PDF|title=Delta III Payload Planner's Guide|archive-url=https://web.archive.org/web/20011119102909/http://www.boeing.com/defense-space/space/delta/docs/DELTA_III_PPG_2000.PDF|archive-date=19 November 2001}}</ref>
  |fuel       = [[LOX]]/[[RP-1]]
  }}
  {{Infobox rocket/stage
  |type       =  stage
  |diff       =  <!--variant of rocket this is used on, optional-->
  |stageno    =  Second
  |name       =  [[Delta Cryogenic Second Stage|DCSS]]
  |engines    =  1 × [[RL10]]B
  |thrust     =  {{cvt|110.03|kN}}
  |SI         =  {{convert|462|isp}}<ref name=slrd3>{{cite web|title=Delta III Data Sheet|url=http://www.spacelaunchreport.com/delta3.html|website=Space Launch Report|access-date=26 July 2014}}</ref>
  |burntime   =  700 seconds<ref name=d3ppg />
  |fuel       =  [[LOX]] / [[LH2]]
  }}
  {{Infobox rocket/stage
  |name       = [[Star 48B]]
  |type       = stage
  |diff       = Optional
  |stageno    = Third
  |solid      = yes
  |thrust     = {{cvt|66.723|kN}}
  |SI         = {{convert|286|isp}}
  |burntime   = 87 seconds
  |fuel       = [[HTPB]]
  }}
}}

'''Delta III''' was an [[expendable launch vehicle]] made by [[McDonnell Douglas]] (later acquired by [[Boeing]]). Development was canceled before the vehicle became operational. The vehicle is the third generation of the [[Delta (rocket family)|Delta rocket family]], developed from the highly successful [[Delta II]] to help meet the launch demand of larger satellites. While the Delta III never had a successful launch, some of the technologies developed were used in its successor, the [[Delta IV]].

The Delta III was the first to use the [[Delta Cryogenic Second Stage]], which was designed by the [[National Space Development Agency of Japan]] based on the second stage it developed for the [[H-IIA]] rocket and built by [[Mitsubishi Heavy Industries]]. [[Beyond Gravity|Contraves]] built the fairing and payload adapters based on designs it used on the [[Ariane 4]].

The first Delta III launch was on August 26, 1998.<ref name=wired>{{Cite magazine|url=https://www.wired.com/1998/08/delta-iii-takes-a-dip/|title=Delta III Takes a Dip|magazine=Wired |access-date=2018-10-24|language=en-US}}</ref> Of its three flights, the first two were failures, and the third, though declared successful, reached the low end of its targeted orbit range and carried only a dummy (inert) payload. The Delta III could deliver up to {{convert|3,810|kg|sp=us}} to [[geostationary transfer orbit]], twice the payload of its predecessor, the Delta II.<ref name="Datasheet">{{Cite web|url = http://www.boeing.com/defense-space/space/delta/delta3/delta3.htm|title = Delta III Launch Vehicle|date = 2001|archive-url = https://web.archive.org/web/20011114221110/http://www.boeing.com/defense-space/space/delta/delta3/delta3.htm|archive-date = November 14, 2001}}</ref> Under the four-digit designation system from [[Delta (rocket family)#Delta numbering system|earlier Delta rockets]], the Delta III is classified as the Delta 8930.

== History ==
Due to the continual size and mass growth of commercial satellites in the late 1980s, McDonnell Douglas realized the need for a higher-performance rocket than even their new [[Delta II]]. New satellite bus offerings from [[Hughes Aircraft Company|Hughes]] required a launch vehicle with a 4-meter diameter payload fairing as well as the ability to send 3.5 tons of payload to a [[geostationary transfer orbit]] – neither of which Delta II offered.<ref name=slr>{{cite web |last1=Kyle |first1=Ed |title=Thunder Lost – The Delta 3 Story |url=https://www.spacelaunchreport.com/thorh13.html|archive-url=https://web.archive.org/web/20220321061514/https://www.spacelaunchreport.com/thorh13.html |url-status=dead |archive-date=March 21, 2022 |website=spacelaunchreport.com}}</ref>

Multiple options for evolving the Delta II to support larger payloads were considered in the late 1980s and early 1990s, namely using higher-performing liquid hydrogen/liquid oxygen upper stages. Eventually, the Delta III was announced in 1995, boasting an evolved Delta II first stage and a second stage based on that of the Japanese [[H-II]] rocket. This led to Delta III being similar in size to Delta II, meaning that the existing Delta II infrastructure at [[Space Launch Complex 17|SLC-17B]] could be used after some modifications. Soon after the announcement, Hughes placed an order for 13 Delta III launches.<ref name=slr />

Delta III would only fly three times. The first two launches, both carrying live satellites, ended in failure. The third and final launch, carrying a dummy payload, was only partially successful after the RL-10B second-stage engine shut down prematurely. After commercial interest declined, the Delta III program was officially ended in 2003. Boeing then transitioned their focus to the new [[Delta IV]] rocket, which was much more capable than Delta III.<ref name=slr />

Multiple Delta III rockets were already built and would have been unused, but they were cannibalized for parts for both Delta II and Delta IV.<ref name=slr />

== Description ==
Delta III was developed from the Delta II rocket. The new vehicle sported a modified first stage and a new, more efficient upper stage. This led to Delta III having around double the payload capacity of Delta II. However, the consecutive failures of the initial Delta IIIs, combined with the more advanced [[Delta IV rocket|Delta IV]] program and the continuing success of the Delta II, left the Delta III as an interim vehicle.<ref name="slrd3" />

=== First stage ===
Like the Delta II, the first stage of the Delta III burned kerosene and liquid oxygen and was powered by one [[Rocketdyne]] [[RS-27A]] main engine with two [[LR-101]]-NA-11 vernier engines for roll control.<ref name=anx>{{cite web|title=Delta 3|url=http://www.astronautix.com/lvs/delta3.htm|website=Astronautix|access-date=January 5, 2015|url-status=dead|archive-url=https://web.archive.org/web/20131112150745/http://www.astronautix.com/lvs/delta3.htm|archive-date=November 12, 2013}}</ref> The vernier engines were also used for attitude control after the main engine shut down, just before the second stage separated.<ref name=d3ppg /> While the propellant load and gross mass of the stage were nearly identical to the Delta II, the diameter of the kerosene tank was increased from 2.4 meters to 4 meters, while its height was reduced. The liquid oxygen tank and engine section remained largely unchanged. The redesigned kerosene tank reduced the overall length of the stage and, combined with the increased height of the second stage, allowed Delta III to use the same launch facilities as Delta II with only minor modifications.<ref name="Datasheet" />

The first stage thrust was augmented by nine [[Graphite-Epoxy Motor|GEM]]-46 solid rocket boosters, sometimes referred to as GEM LDXL (Large Diameter Extended Length). These were {{cvt|14.7|m}} meters in length, 1.2 m (46&nbsp;inches) in diameter, and had a mass of 19 metric tons each, about six metric tons more than the Delta II's standard GEM-40 motors. Six were ignited on the launch pad, while the remaining three were ignited just before burnout and separation of the ground-lit boosters. To maintain steering authority, three of the ground-lit boosters had [[Thrust vectoring|vectoring nozzles]].<ref name="Datasheet" /> GEM-46 boosters would later find use on Delta II, creating the Delta II Heavy variant.

=== Delta Cryogenic Second Stage ===
[[File:Delta III second stage.jpg|thumb|left|upright|A Delta III [[Delta Cryogenic Second Stage|DCSS upper stage]] undergoing testing at [[Glenn Research Center#Plum Brook Field Station|Plum Brook Field Station]] in January 1998]]
The second stage of the Delta III was the newly developed [[Delta Cryogenic Second Stage]] (DCSS), which burned liquid hydrogen and liquid oxygen. It was developed and manufactured partly by Mitsubishi Heavy Industries and was based on the second stage of [[JAXA]]'s H-IIA rocket. Boeing was in charge of preliminary design and the development of new technologies, while Mitsubishi Heavy Industries was responsible for manufacturing. The liquid hydrogen tank was {{cvt|4|m}} meters in diameter while the separate liquid oxygen tank (attached by a truss to the bottom of the hydrogen tank) was around {{cvt|3|m}} meters in diameter. This stage offered significantly better performance than the Delta II's second stage, the [[Delta-K]], which burned hypergolic propellants.<ref name="Datasheet" /> The DCSS was powered by a [[Pratt & Whitney]] [[RL10]]B-2 engine, derived from the RL10 powering the [[Centaur (rocket stage)|Centaur]] upper stage but featuring electromechanical actuators for gimbal control and an extending nozzle for increased performance.<ref name=anx /> After Delta III's retirement, the DCSS design was modified for use as the Delta IV's second stage in both the original 4-meter diameter form factor as well as a larger 5-meter diameter stage.<ref>{{cite web|title=Delta 3 Rocket Falls Short, but Still a Success Boeing Says| publisher=SpaceFlightNow| date=August 24, 2000| url= http://spaceflightnow.com/delta/d280/000824loworbit.html}}</ref> A further refinement of the 5-meter diameter DCSS, known as the Interim Cryogenic Propulsion Stage, is used on the Block I [[Space Launch System]] rocket.

Control of the second stage was provided by 4 sets of hydrazine thrusters installed around the bottom of the liquid oxygen tank. During engine burns, these thrusters only provided roll control (as the engine itself could gimbal for pitch and yaw). During coast periods, these would then provide 3-axis control.

=== Star 48B third stage ===
Delta III was offered with an optional [[Star 48]]B solid-fueled third stage. It would have been attached on top of the DCSS and contained inside the payload fairing. The Star 48B would have been used for high-energy orbits, like geostationary or interplanetary missions.<ref name=d3ppg /> It was never flown on Delta III but was commonly used on Delta II missions. The Star 48B has also seen use on Delta IV and Atlas V.

=== Payload fairing ===
Delta III's payload fairing was a new [[composite material|composite]] design, matching the upper stage hydrogen tank's {{cvt|4|m}} diameter and allowing larger payloads than the Delta II's 9.5 or 10-foot-diameter fairing. Delta III's 4-meter fairing was derived from Delta II's 10&nbsp;ft composite fairing.<ref name=d3ppg /> This fairing design would later be repurposed on the Delta IV Medium.

== Launches ==
{{transcluded section|source=List of Delta III launches}}
{{#section-h:List of Delta III launches|Launch history}}

== See also ==
* [[Comparison of orbital launchers families]]

== References ==
{{Reflist}}

== External links ==
*[http://kevinforsyth.net/delta/ History of the Delta Launch Vehicle]
*[http://www.spaceflightnow.com/delta/d280/000821delta.html Spaceflight Now article 8/21/2000]

{{Expendable launch systems}}
{{US launch systems}}
{{Thor and Delta rockets}}

{{Use American English|date=January 2014}}

{{DEFAULTSORT:Delta 3}}
[[Category:Boeing spacecraft and space launch systems]]
[[Category:Delta (rocket family)]]