New big prop, facing the A320 & 737: TurboLiner.
Keesje, my comment re the name was really tongue-in-cheek. That sort of thing is usually done by testing random groups of travelers anyway, not by asking a hoary sampling of ppruners.
In your #58 you said
Quote
If this is to be a 737/A320 replacement dedicated for short high frequency flight, as I stated in the opening post, very short airfield performance is not a basic requirement. It could be an optional package.
Unquote
I wonder. My earlier comment about getting the airplane closer to the passenger really meant getting it into smaller regional airports provided the demographics are right. That seemed sensible to me partly from of the fuel consumption aspect: small airports where turnoff to gate is two-three minutes vs big ones where it could be ten, fifteen, plus holding for other traffic to pass. I realise that would require big rethinking of ATC, terminal facilities, who pays for the new navaids etc but with fuel going the way it is, those little things seem likely to make a big difference in overall operating costs.
I'm probably with Atreyu re electric drives if only based on there being one more thing to go tech.
And I’m totally with mcnuggit re the windows. Hell on the spine having to scrunch down to see outside. Yes you can hear me muttering “Viscount, Electra….”
In your #58 you said
Quote
If this is to be a 737/A320 replacement dedicated for short high frequency flight, as I stated in the opening post, very short airfield performance is not a basic requirement. It could be an optional package.
Unquote
I wonder. My earlier comment about getting the airplane closer to the passenger really meant getting it into smaller regional airports provided the demographics are right. That seemed sensible to me partly from of the fuel consumption aspect: small airports where turnoff to gate is two-three minutes vs big ones where it could be ten, fifteen, plus holding for other traffic to pass. I realise that would require big rethinking of ATC, terminal facilities, who pays for the new navaids etc but with fuel going the way it is, those little things seem likely to make a big difference in overall operating costs.
I'm probably with Atreyu re electric drives if only based on there being one more thing to go tech.
And I’m totally with mcnuggit re the windows. Hell on the spine having to scrunch down to see outside. Yes you can hear me muttering “Viscount, Electra….”
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Atreyu, broadreach, thnx for your ideas. Regarding the failure rate of the electric drive system, I guess a suitable MTBF could be engineered in. If it is not functioning a (slow) push back on one drive should be possible, or a conventional tug could do the job. It's not a no go item.
Still if it works 99.x % of the time it means a dramatic reduction of airport noise & air contamination. It might pursuade airport authorities to allow more flights or at early/late hours or alternative runways. For e.g charter and low cost airlines this would add value compared to existing types.
Of course a lighter simplified ATR / BAE 146 type of gear could be specified. I included it in the sketch.
Changes compared to earlier sketch:
Still if it works 99.x % of the time it means a dramatic reduction of airport noise & air contamination. It might pursuade airport authorities to allow more flights or at early/late hours or alternative runways. For e.g charter and low cost airlines this would add value compared to existing types.
Of course a lighter simplified ATR / BAE 146 type of gear could be specified. I included it in the sketch.
Changes compared to earlier sketch:
- Additional escape window (required)
- Alternative simplified main landing gear
- Wing - engine pylon fairing
- Belly access doors
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I am sure that this is not the sort of feedback that you are looking for but it may nevertheless be useful. Speaking as a passenger, I used to commute regularly between Lagos/Ibadan/Kaduna/Benin, over a period of 4 years, some time ago.
The workhorse of these routes was the F27 but occasionally an F28 was used.
There was a huge difference in ‘comfort’ between these two. The noise/vibration/harshness of the F27 was not something that one looked forward to. But more importantly, IMO, it was the limited service ceiling or cruising ceiling that made the F27 particularly uncomfortable because most of the time it could not rise above the bumpy air. The type of discomfort I am talking about is not just a regular jolt or two that people nowadays seem to refer to as turbulence. No, this was the real difficult stuff that could pin the cabin staff to the ceiling for a good few seconds, and leave one's hips bruised and chaffed by the seatbelt. I therefore developed an aversion to the F27 and their ilk. In the F28, I could often see the weather well below, and could walk straight when I got off.
Would your design be better than this for comfort? If not, passengers will eventually shun it. The answer is to design one that can get above the weather, easily. Is a 25,000ft service ceiling enough? Wasn't that the service ceiling of the Bristol Britannia in the 1950s? Surely engine and propeller technology has improved since then.
I follow your posts with interest, on Airlinersnet as well, if I am allowed to say that.
rgds
The workhorse of these routes was the F27 but occasionally an F28 was used.
There was a huge difference in ‘comfort’ between these two. The noise/vibration/harshness of the F27 was not something that one looked forward to. But more importantly, IMO, it was the limited service ceiling or cruising ceiling that made the F27 particularly uncomfortable because most of the time it could not rise above the bumpy air. The type of discomfort I am talking about is not just a regular jolt or two that people nowadays seem to refer to as turbulence. No, this was the real difficult stuff that could pin the cabin staff to the ceiling for a good few seconds, and leave one's hips bruised and chaffed by the seatbelt. I therefore developed an aversion to the F27 and their ilk. In the F28, I could often see the weather well below, and could walk straight when I got off.
Would your design be better than this for comfort? If not, passengers will eventually shun it. The answer is to design one that can get above the weather, easily. Is a 25,000ft service ceiling enough? Wasn't that the service ceiling of the Bristol Britannia in the 1950s? Surely engine and propeller technology has improved since then.
I follow your posts with interest, on Airlinersnet as well, if I am allowed to say that.
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Turboliner
Re Jstflyin, the Russians were quite good at it. Have a look at the IL 18 http://en.wikipedia.org/wiki/Ilyushin_Il-18 of 50 years ago. The oxygen mask argument which I have heard or seen before is a bit flat-earth, imo. I like Keejse’s design proposals, but I also like my comfort, and so do most people. Comfort costs money but is appealing to the customer and therefore good for business. The more that can be demonstrated the more likely someone will look seriously at such designs. Is it impossible to incorporate the comfort factor and keep down operating costs? Maybe. But on a much smaller scale Saab appear to be making a good job of it.
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I assume the door will be >6ft above the ground when on the gate... if that's correct, then I think you'd need means to assist evacuation from the emergency windows (as there is no wing there). Given this, I think a smaller door (739 style) will be better to be put where the emergency exit windows are, or maybe move it clear off the sponsons... as you need a slide from the exit and you don't want it to get poked by the wheelbay door or landing gear mechanism.
Anyways, nice stuff Keesje, although I was wondering if someone would do a mini Tu114 twin... *grin*
Anyways, nice stuff Keesje, although I was wondering if someone would do a mini Tu114 twin... *grin*
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Some comments on the aerodynamic configuration, if I may.
Control System Architecture
Looks like the elevator and rudder are manual, or at best hydraulically-boosted manual. (Tabs on both surfaces, horns on the elevators). Yet the ailerons have no tabs of any kind, and you've got "high speed" ailerons, which implies to me a purely hydraulic solution for roll control. I don't think that's a consistent approach; you're going to have to build in a level of hydraulic redundancy to address the roll axis, so you may as well use the same systems for the other axes too.
I'm not convinced of the need for a "high speed" aileron option, nor am I convinced that not having spioilerons is a good choice.
I see no provision for ground lift dumping, other than the slightly oddly located "direct lift spoilers". Why are they so far forward - they are going to infringe on the fuel tank volume sat in the middle of the chord. Usually they'd go just ahead of the flaps so they could mount on the rear spar.
The h tail looks a bit small, as indeed does the rudder.
The wing isn't "dressed" so I'm guessing you're assuming artificial stall protection?
It looks like you've got AI protection only either side of the nacelle - with the new rules for icing that unprotected outboard wing is going to be a real drag, no pun intended. If you're going to leave the wing unprotected you'll need a big wing, and still may have problems.
The wing/body fairing looks too small, just by eye.
Re the emergency exits: maybe you can argue that the UC door is the step-down surface and avoid slides? Need to align the forward exit with the gear door in that case.
Control System Architecture
Looks like the elevator and rudder are manual, or at best hydraulically-boosted manual. (Tabs on both surfaces, horns on the elevators). Yet the ailerons have no tabs of any kind, and you've got "high speed" ailerons, which implies to me a purely hydraulic solution for roll control. I don't think that's a consistent approach; you're going to have to build in a level of hydraulic redundancy to address the roll axis, so you may as well use the same systems for the other axes too.
I'm not convinced of the need for a "high speed" aileron option, nor am I convinced that not having spioilerons is a good choice.
I see no provision for ground lift dumping, other than the slightly oddly located "direct lift spoilers". Why are they so far forward - they are going to infringe on the fuel tank volume sat in the middle of the chord. Usually they'd go just ahead of the flaps so they could mount on the rear spar.
The h tail looks a bit small, as indeed does the rudder.
The wing isn't "dressed" so I'm guessing you're assuming artificial stall protection?
It looks like you've got AI protection only either side of the nacelle - with the new rules for icing that unprotected outboard wing is going to be a real drag, no pun intended. If you're going to leave the wing unprotected you'll need a big wing, and still may have problems.
The wing/body fairing looks too small, just by eye.
Re the emergency exits: maybe you can argue that the UC door is the step-down surface and avoid slides? Need to align the forward exit with the gear door in that case.
Hasn't the idea of Wheeltug" been done to death somewhere else on Pprune? Seems like a needless complication. But, the design does look promising.
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Fascinating effort, just great. I like the DLC (from the 1011?) that mitigates the low level burbling. I think you're off base on the "wheeltug" concept, though. Anything that incorporates ground handling costs in favor of the Landing authority is not a good economic design. In other words, once my aircraft is on the deck, it's a truck. Airplanes are not good trucks (or tugs), and logically it is counter design to try to mitigate what is arguably the ground's duty. I would try to interest others in building new tug designs, vehicles that are more versatile and can be designed to travel (while towing) greater distances. If you look at the cost of carrying around (wheeltug) extra weight, over the useful life of your aircraft, then add maintenance, I don't see the advantage. I guess I'm saying tugs don't fly, A/C don't tug. Offering an expensive perk to the ground authority without payment, is not good business. If you're flying into tugless strips, be happy with your propellors, not your Jet sucking hot pipes. I think you'll like Hotel. Keep going, all the best.
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Simplifications
Would your design be better than this for comfort? If not, passengers will eventually shun it.
The new engine / prop I proposed is the TP400. It is developed to turn slower and avoid the typical tip effects and has better turbine noise isolation.. http://www.youtube.com/watch?v=h-V5jzSslZo It will allow the A400M to use civil airways flying M0.7 at up to 37.000 ft.
Apart from that it seems passenger comfort is really moving down the priority list as airlines struggle to survive the constantly rising fuel prices. http://www.iht.com/articles/2008/03/24/business/turbo.php
As said earlier, the shorter the trip, the better the turboprops look. I summarized a selection of city pairs in Europe. More then 700 million people live in Europe, but the more wealthy ones live in the western part, all very close together. As can be seen most major city pairs are closer then 400nm. Very high frequency flights are flown, often even by twin aisles.. Then there are flogs of 737 / 320 aircraft doing low cost flights within the same area. The big hubs are seriously restricted. A different situation then e.g. the US or Asia..
I think you'd need means to assist evacuation from the emergency windows (as there is no wing there). Given this, I think a smaller door (739 style) will be better to be put where the emergency exit windows are, or maybe move it clear off the sponsons... as you need a slide from the exit and you don't want it to get poked by the wheelbay door or landing gear mechanism.
PK-KAR good point. The doors won't very very high, but high enough to have some kind of slope. I moved them and made them bigger.
I was wondering if someone would do a mini Tu114 twin
http://video.google.com/videoplay?docid=7136291503511317285&q=&hl=en
I don't think that's a consistent approach; you're going to have to build in a level of hydraulic redundancy to address the roll axis, so you may as well use the same systems for the other axes too.
I'm not convinced of the need for a "high speed" aileron option, nor am I convinced that not having spioilerons is a good choice
I see no provision for ground lift dumping, other than the slightly oddly located "direct lift spoilers". Why are they so far forward - they are going to infringe on the fuel tank volume sat in the middle of the chord. Usually they'd go just ahead of the flaps so they could mount on the rear spar.
The DLC is something different then ground spoilers. They are used inflight to decent is a very precise without changing angle.The lift distribution on a supercritical wing is spread out over the chord. Placing close to the flaps would have limited effect. Aircraft like the L1011, F14 and gliders have a DLC system. The spoilers on the Turboliner are not as big as conventional spoiler and can be fully extended when the gear is on the ground.
On the wheeltug system: most see it as a burden. I guess if you fly an aircraft priorities are reliability and performance. When buying and aircraft and negotiating with airport authorities on landing right & evening slots, rising fuel prices, environment targets, growth and noise pollution, other priorities come in. In terms of weight and reliability electric systems aren't what they used to be (ref. 787). The installation would be a few hundred lbs but save fuel.
Still I changed the design to a conventional ARJ type of gear to satisfy concerns put on the table by many (airfoilmod)
thnx for the comments! rgds keesje
I quite like the idea of DLC, but in practice on the L1011 - it wasn't so useful. It was designed to prent big lift changes with small attitude changes on the approach. In practice, it was awkward, added weight, difficult to maintain and was eventually disabled by a lot of L1011 operators. As for the crews, you either loved it or hated it. And when activated, it made the landings somewhat firm in a lot of instances.
Also, have you thought about the effect of positioning the spoilers in the accelerated flow behind the props? If they're used in flight, I reckon you will get quite a bit of buffeting.
Also, have you thought about the effect of positioning the spoilers in the accelerated flow behind the props? If they're used in flight, I reckon you will get quite a bit of buffeting.
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Airbus to test electric drives this year on A320.
No that you'll have convinced me electric drive maybe isn't a good idea:
Maybe it is a good idea afterall ?
Dan, I've got to take a closer look at DLC & buffeting. As I mentioned the Turboliner is made to do high frequency short flights from busy airports.
The L1011 was developed nearly 40 years ago without 7-8 approaches a day in demanding airport environments in mind. Fly-by-wire wasn't on the capability list either. (great machine though).
I was thinking on more subtile spoiler system then the conventional big plates killing lift after touchdown. More of a very responsive automated system continuously translating pilot inputs into a combination of various controlsurface movements to achieve smooth height adjustments without gaining speed or changing pitch..
Airbus could run electric taxi demonstration on A320 this year.
Airbus could undertake a demonstration of an electric taxi system on an A320 this year as part of studies to reduce fuel burn and emissions.
http://www.flightglobal.com/articles...a320-this.html
Airbus could undertake a demonstration of an electric taxi system on an A320 this year as part of studies to reduce fuel burn and emissions.
http://www.flightglobal.com/articles...a320-this.html
I quite like the idea of DLC, but in practice on the L1011 - it wasn't so useful. It was designed to prent big lift changes with small attitude changes on the approach. In practice, it was awkward, added weight, difficult to maintain and was eventually disabled by a lot of L1011 operators. As for the crews, you either loved it or hated it. And when activated, it made the landings somewhat firm in a lot of instances.
Also, have you thought about the effect of positioning the spoilers in the accelerated flow behind the props? If they're used in flight, I reckon you will get quite a bit of buffeting.
Also, have you thought about the effect of positioning the spoilers in the accelerated flow behind the props? If they're used in flight, I reckon you will get quite a bit of buffeting.
The L1011 was developed nearly 40 years ago without 7-8 approaches a day in demanding airport environments in mind. Fly-by-wire wasn't on the capability list either. (great machine though).
I was thinking on more subtile spoiler system then the conventional big plates killing lift after touchdown. More of a very responsive automated system continuously translating pilot inputs into a combination of various controlsurface movements to achieve smooth height adjustments without gaining speed or changing pitch..
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I think you are on target with DLC. It is an effective enhancement to stability and ride. Don't get too excited about wheel motors. Keep in mind it is early on, and the French (EU) obsession with IPCC and Climate change is a bit behind the curve (not in front). If I had the space I'd offer my arguments against the concept. It doesn't make sense even if the APGW arguments do. My suggestion to all who are interested is to enhance ground movers, they are more in their realm pulling heavy A/C and could be much improved, even to the extent of meeting heavies at the High Speed exit and transporting them to Gate (Stand) with A/C engines shut down. Or for that matter, tugging them out to the penalty box for runup prior to launch.
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Hi Keesje, Thanks for the u tube and other link. I am partially relieved. I can see the sense in what you propose; just flagging up passenger comfort. I look forward to the increased short sector convenience.
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Interesting discussion, some quick remarks (doesn't claim to be complete) concerning the current configuration:
- Range: You have to offer more. Take a look at the history of the Mercure and it's lack of range.
- Weight: Your assumptions concerning the OEW are very optimistic.
- Wing design: Right now not comprehensible.
- Space: During the detailed design-process, it's much easier to scale something down, than adding additional things. From my point of view, there is a lack of space for everything, especially for avionics and several supply units. Possibly, parts of the main landing gear an the wing will extend into the cabin and you have to remove some seats and you have to add an extra row: Add one or two meters of length to be prepared.
- Emergency Exits: The current configuration is inflexible for cabin design. And try to avoid the use of emergency slides.
- "roof top windows": You have allready mentioned the problems concerning high tension. It's not impossible to install some windows, but be prepared for a lot of problems.
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I'm not kidding, just trying to find more customers 
.
Short Version of the argumentation:
By offering more range, the airlines could boost their cycle ratio by flying alternatly short hops and medium haul routes.
.Short Version of the argumentation:
By offering more range, the airlines could boost their cycle ratio by flying alternatly short hops and medium haul routes.
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But then all your accomplishing is carting around unnecessary Fuel. Parallel to my Wheel tug argument: Why carry around in the air that which is better suited at the Gate (or in the Truck)? If your long sector includes stops, assumed, otherwise buy n Fly 73-, then Uplift on the go. The most expensive place to store fuel (or a tug) is ONBOARD.
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Shrink option, TP400 engines further testing testing picture
#1 Many people say the Turboliner as specified might be too big. I envision the Aircraft as a direct 737 / A320 replacement on shorter stretches <800nm4), not for long stretches. The A320 /737 are optimized for routes up to 3000nm.
Obviously offering a shrunk version of the Turboliner, would be an option. Europrop says the TP400 has growth potential so a future stretch would be possible also.
I sketched a shrink of about 150 inch / 5 seatrow / 30 seats.
#2 the TP400's first flights in getting closer finally. The Herc that has been modified is doing test runs (photo flightglobal). Note the additional struts that have been added to transfer loads/moments, damp vibrations, add structural stiffness or a combination..
A part throttle setting at lower speeds / take-off seems neccessary.
Obviously offering a shrunk version of the Turboliner, would be an option. Europrop says the TP400 has growth potential so a future stretch would be possible also.
I sketched a shrink of about 150 inch / 5 seatrow / 30 seats.
#2 the TP400's first flights in getting closer finally. The Herc that has been modified is doing test runs (photo flightglobal). Note the additional struts that have been added to transfer loads/moments, damp vibrations, add structural stiffness or a combination..
A part throttle setting at lower speeds / take-off seems neccessary.
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I've followed your work and think highly of it. With respect I'd like to play Devil's advocate for a moment. Your attention to detail is impressive, and you innovate on the fly, a very admirable quality in design. Let me ask you a couple simple and sincere questions. The Hercules is approaching sixty years of age, yet is present in large numbers, relied upon by both military and civilian owners, and has a pedigree and fact sheet that remains unequalled in many ways. Would you discuss by way of affirming your approach the need for wildly complex "improvements" and "tweaks" when an airframe of the 130's record of performance stands alone? Imagine 13k horsepower per side and fans you propose on an airframe that can be configured to carry ~250 pax (or more) transcontinental? A Twin Herc? Again, this is what if? To further Frame your work, if you will.
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thnx for your kind words. I agree with you the C130 has a place of its own. I think it is becoming clear to its operators that its cargo deck and load carrying capasity is reaching its limits. Airforces want to move heavier / bigger equipment than the C130J can handle.
Its 20t capasity doesn't have much competition, the A400 is significant larger, the C27 significant smaller. The Brazilians smell an opportunity and seem to step in with the C-390 that has already attracted interest.
For passenger use I think a good militairy cargo aircraft will have a hard time becoming a good passenger aircraft. A big cross section / large cargo deck & heavy landing gear seems to contradict low drag / frontal surface. Then there is big door in the back. Structural weight & aerodynamics are probably not optimal for passenger service.
News today is that GE foresees its new heavy 8000 hp turboshaft under development for the CH53K to potentially play a role on fixed wing aircraft..
GE plots GE38 engine's future in emerging heavylift market
Its 20t capasity doesn't have much competition, the A400 is significant larger, the C27 significant smaller. The Brazilians smell an opportunity and seem to step in with the C-390 that has already attracted interest.
For passenger use I think a good militairy cargo aircraft will have a hard time becoming a good passenger aircraft. A big cross section / large cargo deck & heavy landing gear seems to contradict low drag / frontal surface. Then there is big door in the back. Structural weight & aerodynamics are probably not optimal for passenger service.
News today is that GE foresees its new heavy 8000 hp turboshaft under development for the CH53K to potentially play a role on fixed wing aircraft..
GE plots GE38 engine's future in emerging heavylift market