FredT From United Kingdom, joined Feb 2002, 2184 posts, RR: 26 Reply 1, posted (6 years 3 months 2 days 2 hours ago) and read 4467 times:
I'd say it is mainly down to ground clearance. The penalties associated with rear engines are less severe than the penalties of heightening the main landing gear.
It is also a very fashion sensitive segment.
I thought I was doing good trying to avoid those airport hotels... and look at me now.
N231YE From , joined Dec 1969, posts, RR: Reply 2, posted (6 years 3 months 2 days ago) and read 4426 times:
Back in the 1950s, the Douglas Corporation did develop a small, wing-mounted engine Business Jet, powered by 4 Westinghouse turbojets in individual pods (consider it a "pocket sized-DC-8" ). I cannot find a picture of the sole prototype on the internet...let alone, the model number.
I'll leave this job up to 2H4 to find the aircraft!
Also, don't forget the HondaJet, the ABJ, and the BBJ, all have wing mounted engines, though I know these aren't what you are picturing.
To answer your question, I believe clearance and quietness in the cabin are contributing factors as to having the engines mounted to the rear fuselage.
Flyf15 From , joined Dec 1969, posts, RR: Reply 4, posted (6 years 3 months 1 day 23 hours ago) and read 4404 times:
Quoting N231YE (Reply 2): Back in the 1950s, the Douglas Corporation did develop a small, wing-mounted engine Business Jet, powered by 4 Westinghouse turbojets in individual pods (consider it a "pocket sized-DC-8" ). I cannot find a picture of the sole prototype on the internet...let alone, the model number.
That'd be the McDonnell 220. Sweet little jet... I'd like to find the (sole) existing example and buy it... if I win the lottery.
N231YE From , joined Dec 1969, posts, RR: Reply 5, posted (6 years 3 months 1 day 23 hours ago) and read 4379 times:
Quoting Flyf15 (Reply 4): That'd be the McDonnell 220. Sweet little jet... I'd like to find the (sole) existing example and buy it... if I win the lottery.
You beat 2H4 to it, that was the aircraft that I was looking for!
Flyf15 From , joined Dec 1969, posts, RR: Reply 6, posted (6 years 3 months 1 day 20 hours ago) and read 4322 times:
Quoting N231YE (Reply 5): You beat 2H4 to it, that was the aircraft that I was looking for!
One very neat tidbid about the McDonnell 220 is that they originally tried to market it to airlines as a high speed luxury jet that would seat around 10. They were in talks to sell 170 of them to PanAm, but that fell through and later on, so did the entire program. Can you imagine that thing as the first true, small jet airliner? Would've been awesome...
KELPkid From United States of America, joined Nov 2005, 5932 posts, RR: 4 Reply 8, posted (6 years 3 months 1 day 20 hours ago) and read 4310 times:
Quoting Flyf15 (Reply 4): That'd be the McDonnell 220. Sweet little jet... I'd like to find the (sole) existing example and buy it... if I win the lottery.
Sitting on the ground at ELP currently...tucked away out of the public's view between the T-hangars and US Customs.
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
N231YE From , joined Dec 1969, posts, RR: Reply 10, posted (6 years 3 months 1 day 18 hours ago) and read 4279 times:
Quoting Flyf15 (Reply 6): One very neat tidbid about the McDonnell 220 is that they originally tried to market it to airlines as a high speed luxury jet that would seat around 10. They were in talks to sell 170 of them to PanAm, but that fell through and later on, so did the entire program.
Interesting. I remember reading about the program, which was originally intended as a jet trainer for the USAF. When that fell through, McDonnell (prior to the Douglas merger) tried to market it as a business jet (and for the airlines). Then of course, the whole project failed.
Quoting Flyf15 (Reply 6): Can you imagine that thing as the first true, small jet airliner? Would've been awesome...
Just stretch it a little bit and you'd have the world's first RJ!
KELPkid From United States of America, joined Nov 2005, 5932 posts, RR: 4 Reply 13, posted (6 years 3 months 1 day 16 hours ago) and read 4245 times:
Quoting 2H4 (Reply 12): Who is the current owner? That thing should be in a museum.
2H4
I tried to look up N4AZ in the FAA database, and got this:
Quote:
ATTENTION!
This aircraft's registration status may not be suitable for operation.
Please contact the Aircraft Registration Branch at 1-866-762-9434 for additional information.
Continue
D'oh!
EDIT: got this by clicking the "Continue" link:
Quote:
Aircraft Description
Serial Number 1 Type Registration Individual
Manufacturer Name MCDONNELL DOUGLAS Certificate Issue Date None
Model 220 Status In Question
Type Aircraft Fixed Wing Multi-Engine Type Engine Turbo-Jet
Pending Number Change None Dealer No
Date Change Authorized None Mode S Code 51124007
MFR Year None Fractional Owner NO
Metroliner From United Kingdom, joined Jan 2007, 1058 posts, RR: 1 Reply 20, posted (6 years 3 months ago) and read 3933 times:
to come back on topic, isn't FOD a major hazard with mounting jets that low to the ground? if you can imagine a citation-seized jet with wingmounted pods a la the 737, it would basically be a great hoover just churning up all the guck off the floor.
business jets are generally operated into more demanding fields than commercial jetliners, therefore lowering the risk of FOD is more vital. whereas 737s can afford to have their blades whirling inches off the deck, because they operate mostly from carefully checked runways and aprons, private jets running medivacs sometimes even have to land on grass fields, where FOD is obviously a much greater concern.
KELPkid From United States of America, joined Nov 2005, 5932 posts, RR: 4 Reply 21, posted (6 years 2 months 4 weeks 1 day 23 hours ago) and read 3927 times:
Quoting Metroliner (Reply 20): whereas 737s can afford to have their blades whirling inches off the deck, because they operate mostly from carefully checked runways
Well, the 737-200 did have an "unimproved" landing surface kit available, used extensively by AS off of many gravel runways up in Alaska...IIRC, it consisted of a fender for the nosegear wheels, and vortex generators whose job was to redirect airflow from areas where gravel could be kicked up away from the "suck zone" around the engine inlets...
However, as a former lineboy, I'd be very hesitant about marshalling a jet where the engines are much closer (like under the wings) as opposed to on the tail...
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
i've heard that those things could be a right pain in the neck sometimes! i doubt they'd work on citation-sized scale, though... it's just easier to build tail-engined jets and not have to worry about further complicating the design.
also, another reason might be that tail-engined small jets have a clean wing that improves their performance?
Lightsaber From United States of America, joined Jan 2005, 10685 posts, RR: 100 Reply 23, posted (6 years 2 months 4 weeks 1 day 21 hours ago) and read 3893 times:
Quoting FredT (Reply 1): I'd say it is mainly down to ground clearance. The penalties associated with rear engines are less severe than the penalties of heightening the main landing gear.
Exactly. If a door is (IIRC) 5'6" or more off the ground, the expense of a slide is also required. Hence why many small aircraft opt for tail mounted engines.
I myself am a fan of wing mounted engines for a variety of reasons:
1. The structure to transfer the thrust from the tail to the wing is pretty heavy. Do not forget that the wing is most of the airframe drag.
2. Moment at the wing root. Basically, by having the engines on the airframe, the wing must be reinforced at its root to transfer that weight to the landing gear. In the case of the Hondajet, having the engines above the wing reduces that stress. Thus... a potential weight savings. And weight is always the enemy of aircraft.
Another reason why tail engines are usually employes is that if the thrust is not on the airframe centerline, thrust adjustments will pitch the aircraft. In small airframes this is often very undesirable. Hence why the Do328 jet and Honda jet both have their pylons bring the engines back to the aircraft centerline (or close enough). In an engine out scenario, a short aircraft with the thrust off of the centerline would be a bear to fly.
I'm going to be very curious to see how the Hondajet does vs. the existing business jets and the Phenom 300.
Quoting FredT (Reply 1): It is also a very fashion sensitive segment.
Viscount724 From Switzerland, joined Oct 2006, 21488 posts, RR: 24 Reply 24, posted (6 years 2 months 4 weeks 1 day 19 hours ago) and read 3876 times:
Quoting KELPkid (Reply 21): Quoting Metroliner (Reply 20):
whereas 737s can afford to have their blades whirling inches off the deck, because they operate mostly from carefully checked runways
Well, the 737-200 did have an "unimproved" landing surface kit available, used extensively by AS off of many gravel runways up in Alaska...IIRC, it consisted of a fender for the nosegear wheels, and vortex generators whose job was to redirect airflow from areas where gravel could be kicked up away from the "suck zone" around the engine inlets...
Two Canadian carriers, Pacific Western and Nordair, which later became part of Canadian Airlines, ordered several 737-200Cs (combi model with main deck cargo door) with the gravel runway kit. Canadian North and First Air, the two current jet operators serving the far northern regions of Canada, still operate the type into several airports which lack paved runways, and to gravel airstrips serving mine sites etc.
The gravel deflector attached to the nosegear retracts into a housing ahead of the gear doors and the bleed air nozzles protruding from the lower front edge of the engine intakes blows air down and forward to reduce debris ingestion. Both are visible in the following photos. I believe the kit also included reinforced main landing gear with slightly larger wheels/tires/brakes and a special Teflon coating on the lower fuselage/wings to reduce damage from flying gravel. They also had the most powerful -17 version of the JT8D.
25 FredT: Not to mention the structure needed to transfer the weight of the engines to the wing. Rgds, /Fred
26 LimaNiner: Couldn't one "spiff up" the appearance of engines mounted above the wing by enclosing them in a smooth little "bump", like the engines on the B-2? I
27 KELPkid: How about embedding the engines into the wing root/fuselage junction, like the DeHavilland Comet did? Any reason this wouldn't work for a bizjet? How
29 FredT: You provided your own answer. Junk hanging below the wing doesn't damage the aerodynamic performance much, but junk on top of the wing will. That's w
30 HangarRat: I'd be interested to see a video of a 732 taking off from a gravel strip. I know there was a video posted of a 727 taking off from a dirt strip somewh
31 2H4: I've never seen it myself, but I suspect that if the nozzles are doing their job, nothing apparent would be happening. 2H4
32 N231YE: They're designed to take bleed air off of the compressor and and break up vortices that form in front of the engine (as pictured). These vortices hav
33 FredT: And if you have ever stood in front of a taxiing heavy, watching that engine get closer and closer while it is sucking a thick funnel of water up fro
34 KELPkid: I'm sure it was a telephoto lens...airport security would've stopped anyone foolish enough to be that close to a taxiing heavy Unless the photo wa
36 Ferrypilot: From an aircraft handling point of view and especially if you lose an engine, ...centerline thrust is the far superior configuration. View Large View
37 Lightsaber: There are a few more certification issues though... a pylon is inherently a vibration isolator. Engines embedded into the wings now require a lot mor
Sponsor Message: 
From United States of America, joined Jan 2006, 245 posts, 
From United Kingdom, joined Feb 2002, 2184 posts, 
From Hong Kong, joined Feb 2004, 15870 posts, 
From Germany, joined Apr 2004, 2530 posts, 
From Switzerland, joined Oct 2006, 21488 posts, 
Sponsor Message: 
Printer friendly format
