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Topic: 717 Compared To DC-9
Username: BigGiraffe
Posted 2000-02-19 03:06:27 and read 1400 times.

The new Boeing 717 (not the old USAF KC-135) is an updated version of one of the Douglas DC-9 models. Which one is it closest to, and what are the major differences?

Topic: RE: 717 Compared To DC-9
Username: Matt D
Posted 2000-02-19 03:28:15 and read 1226 times.

The 717 is probably closest to the DC-9-20 in terms of size. The external differences are the blunt tail cone, the extension of the tail above the horizontal stabilizers and the much "fatter" engines.
Other differences include updated avionics and better more efficent and quieter engines.

Topic: RE: 717 Compared To DC-9
Username: Dl_mech
Posted 2000-02-19 03:41:48 and read 1218 times.

I thought it was a few inches longer than a -30, I could be wrong. Does anyone know if the wing i from the -80 or if it is new.

Topic: RE: 717 Compared To DC-9
Username: Dc-9-10
Posted 2000-02-19 04:15:17 and read 1214 times.

all I can see that is a difference is that the 717 has huge ass engines that make the plane look tiny

Topic: RE: 717 Compared To DC-9
Username: USAirways737
Posted 2000-02-19 04:23:03 and read 1210 times.

Boeing says the 717 is similar in size to the dc9-30. But a lot more efficient, better technology, and more spacious, comfortable interior. Oh and the "huge ass" engines.

Topic: RE: 717 Compared To DC-9
Username: Acvitale
Posted 2000-02-19 04:23:22 and read 1213 times.

The B-717 MD95 is a size similar to the DC-9-40 series. Slightly larger than a 30 slightly smaller than a 40....

It has a hybrid wing that is neither from the MD80/MD90/nor DC-9 but a bit larger than the 9 wing and smaller than the MD80/90 wing...

Type rating is still DC-9 for the type to my knowledge with only a changes course required for 9 rated pilots...

Topic: RE: 717 Compared To DC-9
Username: Critter
Posted 2000-02-19 13:54:12 and read 1184 times.

The B717 is actually 124 feet long, that is 1 1/2 feet shorter than the DC9-40. It was originaly to be the same size as the DC9-32 but was stretched at the launch customer Airtran's request. The stretch was placed forward of the wings to compensate for the additional weight from the BMW/Rolls Royce BR715 engines.

The wings are the same size as the DC9-32 with a span of 93 feet 4 inches however they are more of a high lift wing very similar to that on the MD-80. In fact I thought I heard that it is actually the outer portion of the MD-80 wing minus the first 48 inches of the inboard root.

The engines are BMW/Rolls Royce. The B717 comes with two options for thrust rating, 18k and 21k. The thrust rating can be changed by simply changing a data plug on the Engine Electronic Controller (EEC) which may take all of fifteen minutes with no trimming required.

The basic design of the B717 is very similar to that of the tried and true DC-9. However there were alot of changes made particulary in the navigation funtions and capabilities. There is only one analog gauge in the cockpit, it is for the crew oxygen pressure. Everything else is either on one of six LCD displays acroos the front of the cockpit or a small LCD Integrated Standby Instrument System (ISIS). Most of the general systems such as Hydraulics, Fuel, Air Conditioning, and Pressurization maintain the same idea, but are now controlled by computers that allow for interogation by a Centralized Fault Display System (CFDS), allowing easier maintenance and troubleshooting.

From a maintenance and operational standpoint it is a dream for any DC-9 fan. I can say that I truly enjoy maintaining this A/C and our flight crews love it. I think that you will be seeing alot more of this aircraft for a very long time.

critter

Topic: RE: 717 Compared To DC-9
Username: BigGiraffe
Posted 2000-02-19 15:26:22 and read 1177 times.

Since the DC-9-30 was the most popular model prior to the DC-9-80, renamed MD-80, it sounds like I can say the 717 is an updated version of the -30 and be about right. That will help me keep it straight in the future. (Hadn't realized what an improvement it was over previous versions, Critter).

Interesting: I had heard a long time ago that the DC-9-80 wing was the DC-9-30 wing with an extension at the base and new tips. But that may have had more to do with converting a -30 plastic model to a -80 than it did the actual aircraft.

Thanks,
BigGiraffe

Topic: RE: 717 Compared To DC-9
Username: TEDSKI
Posted 2000-02-19 15:54:39 and read 1173 times.

To me it looks like an updated DC-9 series 30 model.

Topic: RE: 717 Compared To DC-9
Username: Critter
Posted 2000-02-19 15:54:54 and read 1171 times.

BigGiraffe,

If you want to find some more information on the B717 you can go check out the "Unofficial B717 Homepage" @ http://www.geocities.com/capecanaveral/hangar/4595/index.html This site has lots of great information and some pretty good links to other B717 related information. Here are a couple of pictures of the B717 form the air and also of the cockpit.

Click for large version
Click here for full size photo!

Photo © Lawrence Feir


Click for large version
Click here for full size photo!

Photo © Brian Stevenson



critter

Topic: RE: 717 Compared To DC-9
Username: B727
Posted 2000-02-19 22:23:59 and read 1154 times.

I wonder why Boeing has kept this design? Along with the 737, all they are doing is "re-creating the wheel" At one point boeing stated they were going to scrap the MD-80 project.
Heres a news flash----The 717 (MD-95) is a DC-9/MD-80 highbird. Why not create an aircraft similar to the 727? It was a great work horse for 3 decades. Why are we now phasing out a
great aircraft, and it replacing it with a bird that was supose to compete with the 737, 757?
I guess I feel this way because it is sad to see the 727 say goodbye. These are just my opinion
on the situation.

Glenn

Long live the 727

Topic: RE: 717 Compared To DC-9
Username: D L X
Posted 2000-02-19 23:58:06 and read 1149 times.

Yes, the 717 is a hybrid of the DC9. However, it is smaller than the 737 (much smaller than the 757) and serves a completely different purpose. It is also much more efficient than its predecessor for the task it was designed to do.

Why don't we see a rehash of the 727? The 727 is being phased out because it is very inefficient compared to modern jets. It requires 3 pilots while most other jets require two. It also utilizes 3 engines which are rather inefficient by themselves, but the mere fact that the third engine has to be placed in the fuselage makes maintenance very difficult. So, what to do? Make a 727 that only needs 2 pilots, and 2 engines. Make the engines more efficient, which means they have to be high-bypass. The size of a high bypass engine for a plane the size of a 727 prohibits putting them on the fuselage, so put them under the wings. Without having rear mounted engines, there is no need for a T-tail, so pull the horizontal stabilizers down to the fuselage. Now, make all of these changes, and look at what you have: a Boeing 757. Fact is, the 757 began life as the 727-300 and evolved into the most cost-efficient jet on the planet.

Topic: RE: 717 Compared To DC-9
Username: BigGiraffe
Posted 2000-02-20 00:16:19 and read 1146 times.

Speaking of 757, it was originally going to have the 727 fuselage section (that part is still true), standard 707/727/737 Boeing nose, the 727 wing, and the 727 T-tail. But you save a lot of weight by moving the stabilizers to the fuselage, and the newer nose is more aerodynamic, and they wanted commonality with the 767, so the design evolved...

Topic: RE: DLX
Username: B727
Posted 2000-02-20 00:22:21 and read 1148 times.

I agree with you on your statement above. I am just depressed about the 727 leaving.
I know the 757 is a great plane

Glenn Korec
Long live the 727

Topic: DLX
Username: NKP S2
Posted 2000-02-20 09:02:36 and read 1133 times.

Actually,the #2 engine on the 727 has relatively easy access in spite of it's appearance as being "buried" in the fuselage. Access is through 4 wide opening cowls (2 on each side),and provide more or less top to bottom access without the "fixed cowl" that makes access on some areas of the inboard sides of the #'s 1 & 3 position less than pleasant. (a common malady on rear mounted engines). Engine changes are much easier than the #1 or #3 positions IMO.

Topic: Critter
Username: NKP S2
Posted 2000-02-20 09:30:02 and read 1131 times.

Hi,I wonder if you could answer a question that I have about the 717. I've worked on DC9's and "80's" for years as a mechanic,and still like them and I'm really curious whether the 717 has retained certain "diesel nine" features. Is the rudder throw limiter still a pitot actuated bellows/counterweight deal or did they change it? Are hydraulics still: Left--engine pump/PTU Right---engine pump/electric pump? I wonder if they dispensed with the PTU and went with two electric pumps. I don't know if you had your planes long,or if you got a chance to work on those areas yet,but I would much appreciate any info you can give me. You can E-mail me at: tr2unit@webtv.net if you prefer. Thanks in advance.

Topic: RE: DLX
Username: D L X
Posted 2000-02-20 09:40:39 and read 1129 times.

Okay, but try that #2 engine with hi-bypass engines and it's a different story. For that matter, you realize that the plane has to be designed around that engine, right? It would be too expensive to make a different design for each engine type, and that's why planes like the L1011 only offer one. On top of that, the hi-bypass engines are much larger, of course, and that leaves much less room for the structure to support it. For a narrowbody, that penalty may be unsurmountable.

Also think about ducting issues. For an embedded engine, the plane's #2 must have even spread of air across the surface of the #1 compressor stage (or you'll have a Very Bad Thing). The ducting issue was a very big deal on the L1011, and caused the DC10 folks to just give up and place the whole thing on the tail (another maintenance and structural nightmare of its own).

Basically, you want large engines on the wings for structural reasons, and ease of maintenance.


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