New big prop, facing the A320 & 737: TurboLiner.
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Seems to me that what Airbus really needs is something to fit in between the A321 and the A330-200. At the moment there is a big range/payload gap which we are having to fill with two leased 757's. A310 is now out of production and there seems to be no replacement planned.
I think it is telling how many carriers decided to introduce their older 757s on the Atlantic in the last few yrs. BA, UA, AA, NW, US, DL.. but thats the other thread. Feel free to add aditional comments / ideas there.
Last edited by keesje; 27th Mar 2008 at 08:39. Reason: spelling
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Improving the Turboliner..
Guys, you are making it too easy on me. I didn't want this concept to be trashed & laughed at but a some constructive comments are more then welcome..
Some improvements I think have yet to include (see current configuration above):
Hinged wings outside of the flaps starting inbetween flaps with the flaperons, any thoughts? Think of the total center wing including engine mounting as one big, composites, stiff section.. combined with electric drive it could park anywhere and create a lot of space / better density on restricted airports (LCY).
Thnx in advance !
Some improvements I think have yet to include (see current configuration above):
- Prop - fuselage clearance is large in relation to the size of the vertical stabilizer. Moving the props closer to the c.o.g & reshaping the stabilizer would improve handling during an engine failure at low speed (V1) I think. I'll check what the clearance will be at the A400M & how the vert. stabilizer size compares to other twin props..
- Landing gear in the side view is more of the vertical retracting kind. For a aircraft this size it would require a lot of structure / fairings to accomplish a wide enough wheel base. Better adjust it to the more realistic type as can be seen in the front view (e.g. BAE146).
- Vert. stab. dissapeared in top view (graphic typo)
- Airbrakes. I think aircraft like BAE146 and F100 really benefit from those during steep approaches, any experience? (APU sits in the way though..)
Hinged wings outside of the flaps starting inbetween flaps with the flaperons, any thoughts? Think of the total center wing including engine mounting as one big, composites, stiff section.. combined with electric drive it could park anywhere and create a lot of space / better density on restricted airports (LCY).
Thnx in advance !
Last edited by keesje; 28th Mar 2008 at 16:58. Reason: completion/spelling
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Thnx erikN!
I changed the Turboliner a bit
I think this aircraft would be aimed at the <800 nm market replacing 737-300, A319, BAE146, F100, 717, MD80 and other aircraft used in these markets. Ryanair (and e.g Clickair
) would put in a few more seats..
Other technical details would be:
I changed the Turboliner a bit
- The engines are placed closer to the fuselage to improve asymmetric thrust stability during one engine out situations. The vertical stabilizer is enlarged / reshaped for the same reason.
- Landing gear doors and vertical stabilizer have been corrected from the earlier drawing
- Biggest change: cross section. I think the cargo belly was unnecessary large for the foreseen use of such an aircraft : short range flights to busy places. Cargo is unimportant here and people prefer hand luggage over check-in luggage. The floor was lowered enabling the luggage bins to be enlarged and the lower fuselage was flattened, resulting in a further reduced frontal area ( lower drag) and more space in the cabin.
- The APU Silencer was smoothened out and speed brakes added to assist in steep approaches reducing acoustic footprint in populated airport areas.
- Seat count was increased by 6 seats to 168 in single class 6 abreast, by reducing the seat pitch from 32 to 31 inch. No need to get spoiled
.
I think this aircraft would be aimed at the <800 nm market replacing 737-300, A319, BAE146, F100, 717, MD80 and other aircraft used in these markets. Ryanair (and e.g Clickair
) would put in a few more seats..Other technical details would be:
- Fly by wire
- Sidestick (creating room in relative small cockpit)
- Advanced gust elevation & noise reduction for passenger comfort
- Glass cockpit, low nose, dual HUD for better situational awareness
- Two entrance doors with integrated stairs which together with the self towing capability help reduce turnaround times and ground support dependability.
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Keesje,
I've followed this for a while and I have a few questions :
1/- Why the leading edge flaps ? The #1 behind the props seem to be both an overkill in terms of aerodynamics, weight and dimensions ( they are also subject to the prop wash). I would have thought that the wing behind the engines will already be in a good lift-generating position.
2/-the shoulder wing choice : as a pilot, I've loathed the crosswind susceptibility of airplanes like the Nord 262 or the ATR, because of their narrow landing gear. See the balance of weight savings on a comparison between A/- structural gains in getting away from the project as it is now and B/-the advantages of a low wing, wide landing gear, wing bending moments...etc...
Another advantage of the low wing is the easier integration of the airplane with existing airport gates - that will allow you to do away with at least one integrated airstairs, hence a further weight saving.
Lastly, the fuel system would be simpler, with the added possibility of a centre tank.
Just my two euro cents.
I've followed this for a while and I have a few questions :
1/- Why the leading edge flaps ? The #1 behind the props seem to be both an overkill in terms of aerodynamics, weight and dimensions ( they are also subject to the prop wash). I would have thought that the wing behind the engines will already be in a good lift-generating position.
2/-the shoulder wing choice : as a pilot, I've loathed the crosswind susceptibility of airplanes like the Nord 262 or the ATR, because of their narrow landing gear. See the balance of weight savings on a comparison between A/- structural gains in getting away from the project as it is now and B/-the advantages of a low wing, wide landing gear, wing bending moments...etc...
Another advantage of the low wing is the easier integration of the airplane with existing airport gates - that will allow you to do away with at least one integrated airstairs, hence a further weight saving.
Lastly, the fuel system would be simpler, with the added possibility of a centre tank.
Just my two euro cents.
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My 5 Cents.
Being the pilot of a flying snowball, I welcome the idea of a bigger, better TP.
I like the design! But make the nose looke a little more like the Saab and less like the Dornier and you're home free!
It's all very nice with the electrical tug system, but I feel it will function just as all the other "nice to have capabilities" I have so far seen, and that is occasionally/sporadically. Having complex electronics in an area that will take up a lot of force in everyday operations just doesn't feel sound to me. Reliability and ease of maintenance is very important and any factors compromising this must be taken into consideration.
Also I feel a little sceptic to the gear/wing configuration. It would feel more sturdy having the gear in the nacelles (Fokker and Dash) instead of the ATR-type placement. A high wing I argue will make the plane more sensitive to strong crosswinds.
I also notice you have given the plane speedbrakes similar to the Bae. You would save more just getting rid of them. Remember, it's a turboprop. Not only are they inherrently slow, but they also have a fantastic stopping capability by means of the props... Having liftdumpers/flight spoilers though (Dash) makes a little sense considering manouverability and landing the wing upon touchdown.
By the way, what is all of this for? Looks the buisness, can't be just for fun or is it?
/LnS
Being the pilot of a flying snowball, I welcome the idea of a bigger, better TP.
I like the design! But make the nose looke a little more like the Saab and less like the Dornier and you're home free!
It's all very nice with the electrical tug system, but I feel it will function just as all the other "nice to have capabilities" I have so far seen, and that is occasionally/sporadically. Having complex electronics in an area that will take up a lot of force in everyday operations just doesn't feel sound to me. Reliability and ease of maintenance is very important and any factors compromising this must be taken into consideration.
Also I feel a little sceptic to the gear/wing configuration. It would feel more sturdy having the gear in the nacelles (Fokker and Dash) instead of the ATR-type placement. A high wing I argue will make the plane more sensitive to strong crosswinds.
I also notice you have given the plane speedbrakes similar to the Bae. You would save more just getting rid of them. Remember, it's a turboprop. Not only are they inherrently slow, but they also have a fantastic stopping capability by means of the props... Having liftdumpers/flight spoilers though (Dash) makes a little sense considering manouverability and landing the wing upon touchdown.
By the way, what is all of this for? Looks the buisness, can't be just for fun or is it?
/LnS
Last edited by low n' slow; 30th Mar 2008 at 18:50. Reason: forgot a slight detail
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Hello thnx for all comments / ideas / insights sofar!
Some have commented on the landings gear, should it be located in nacelles.. I have to find out how long they would have to be for a high cabin / big prop. With the required strenght / stiffnes they could become very heavy..
Other comments on the wing location, it could be higher on the fuselage to stay out of the cabin (important for a suggested freighter version), like An-32..
If I have a little time I will list all your suggestions, make trade-offs and incooperate them in a mark III versions.
Please stay tuned / keep your comments / ideas coming to improve the concept.
thnx & rgds
keesje
Some have commented on the landings gear, should it be located in nacelles.. I have to find out how long they would have to be for a high cabin / big prop. With the required strenght / stiffnes they could become very heavy..
Other comments on the wing location, it could be higher on the fuselage to stay out of the cabin (important for a suggested freighter version), like An-32..
If I have a little time I will list all your suggestions, make trade-offs and incooperate them in a mark III versions.
Please stay tuned / keep your comments / ideas coming to improve the concept.
thnx & rgds
keesje
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Keejse,
Very interesting idea. Not sure how hard hotel is on the engine, the ATR seems to do alright, is a lot lighter than an APU.
Some of the problems with it in the ATR sense are you can not refuel with hotel running. It is limited to only 10kts tailwind, and dependent on wind direction we have to turn the bleed off to stop the exhaust gas being sucked in.
If you do go with the apu, something that you can leave running unattended would be great. As I understand most props with apu's require someone on the flightdeck or at the least in the cabin as they don't have automatic fire extinguisher capabilities. I stand to be corrected.
Have you dug around for info on the ATR 92 concept that is on the drawing boards at ATR at the moment. The Q400X is another one in concept at the moment. I personally think the ATR concept is better as it will be a clean sheet design, with a gear design similiar to yours.
I agree with a earlier comment about crosswinds, the problem with the ATR is the wing continues to fly to around 40-50kts, spoilers that dump lift on landing would start to solve some of the issues surrounding the interesting crosswind handling techniques.
Look forward to more concept ideas.
Cheers
Very interesting idea. Not sure how hard hotel is on the engine, the ATR seems to do alright, is a lot lighter than an APU.
Some of the problems with it in the ATR sense are you can not refuel with hotel running. It is limited to only 10kts tailwind, and dependent on wind direction we have to turn the bleed off to stop the exhaust gas being sucked in.
If you do go with the apu, something that you can leave running unattended would be great. As I understand most props with apu's require someone on the flightdeck or at the least in the cabin as they don't have automatic fire extinguisher capabilities. I stand to be corrected.
Have you dug around for info on the ATR 92 concept that is on the drawing boards at ATR at the moment. The Q400X is another one in concept at the moment. I personally think the ATR concept is better as it will be a clean sheet design, with a gear design similiar to yours.
I agree with a earlier comment about crosswinds, the problem with the ATR is the wing continues to fly to around 40-50kts, spoilers that dump lift on landing would start to solve some of the issues surrounding the interesting crosswind handling techniques.
Look forward to more concept ideas.
Cheers
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I'm not sure if Hotel mode generates enough energy for the electric drive.
The aircraft is supposed to push back & taxi without the main engines (props : noise) running as illustrated in the first picture.
http://i191.photobucket.com/albums/z...g?t=1207130960 The engines would be started at a TBD time and place close to the runway. Arrival the same: engines out after leaving the runway.
Idea is electric drive would ease environmental concerns / restrictions but also ease push back requirements, even allowing a certified cabin crew member to perform it, boarding the aircraft by airstairs after ground control approval..
The aircraft is supposed to push back & taxi without the main engines (props : noise) running as illustrated in the first picture.
http://i191.photobucket.com/albums/z...g?t=1207130960 The engines would be started at a TBD time and place close to the runway. Arrival the same: engines out after leaving the runway.
Idea is electric drive would ease environmental concerns / restrictions but also ease push back requirements, even allowing a certified cabin crew member to perform it, boarding the aircraft by airstairs after ground control approval..
Last edited by keesje; 2nd Apr 2008 at 10:15. Reason: additional info
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UDF
Congrats for thinking laterally.
As others advised previously - pax appeal for a turboprop is not as great as a jet. But the economics......
By the way the unducted fan (UDF) did actually work and worked quite well. Refer http://www.flightglobal.com/articles...-propfans.html and maybe another that might lead you to more details http://pdf.aiaa.org/preview/1987/PV1987_1733.pdf
Perhaps a rear mounted UDF similar to the MD80 test might have a greater appeal.
As others advised previously - pax appeal for a turboprop is not as great as a jet. But the economics......
By the way the unducted fan (UDF) did actually work and worked quite well. Refer http://www.flightglobal.com/articles...-propfans.html and maybe another that might lead you to more details http://pdf.aiaa.org/preview/1987/PV1987_1733.pdf
Perhaps a rear mounted UDF similar to the MD80 test might have a greater appeal.
Last edited by an3_bolt; 2nd Apr 2008 at 11:11. Reason: url reference
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Might have posted a little bit hasty 
Recognising APU would be far better...
Since the idea is to taxi WITHOUT the main engine running by means of an electric drive.
Beside that hotel mode seems to have some major disadvantages, as some pointed out: safety issues (prop bake / hot exhaust gases), noise, wind lim. and engine wear.
Nevertheless ATR believes strongly in this system:
Recognising APU would be far better...Since the idea is to taxi WITHOUT the main engine running by means of an electric drive.
Beside that hotel mode seems to have some major disadvantages, as some pointed out: safety issues (prop bake / hot exhaust gases), noise, wind lim. and engine wear.
Nevertheless ATR believes strongly in this system:
Why ATR has not developed an APU for its aircraft?
“ATR offered an innovative alternative to the APU known as the "Hotel Mode". The Hotel Mode concept (i.e. offering air conditioning and electrical power on the ground) was made possible through the application of a propeller brake on the right hand side engine turbine. Thus the weight and added maintenance cost of an APU is spared.
A survey of 20 customers (214 a/c) has been made to gather information about the rate of utilization and the effectiveness of Hotel Mode. The data gathered from ATR Customers have confirmed that Propeller Brake installation is a smart and effective solution welcomed by Airlines due to tangible advantages over APU.
“ATR offered an innovative alternative to the APU known as the "Hotel Mode". The Hotel Mode concept (i.e. offering air conditioning and electrical power on the ground) was made possible through the application of a propeller brake on the right hand side engine turbine. Thus the weight and added maintenance cost of an APU is spared.
A survey of 20 customers (214 a/c) has been made to gather information about the rate of utilization and the effectiveness of Hotel Mode. The data gathered from ATR Customers have confirmed that Propeller Brake installation is a smart and effective solution welcomed by Airlines due to tangible advantages over APU.
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An_3, you may be right about the pax appeal of jet vs props but I have not come across a travel/booking website which gives you the option of choosing which aircraft type you can fly on. Most give the price option, then the date specific option. If you did want to fly only jet it would take a fair bit more digging to find out.
We fly CHC-WLG vs B737, they pass us in the climb/cruise/descent, but generally we are pulling up on the gate in the ATR about the same time as there passengers are getting up out of there seats. No more that 10mins in it, and pax do prefer the ATR as door to door it is debatable who is quicker, no security checks, quicker boarding and deplaning, and they get a cup of coffee as well.
If Cook get a different type Q400/ATR92, then it will be just as quick if not quicker. As airspace gets more congested for NZ standards, speed control increases and jets on short sectors are only really gaining in the cruise, sometimes in the climb and descent, but if they are above us, there is sometimes not the distance to run to get them thru infront. We can go 250kts to about 8nm final, so we get to catch them up near the end a bit.
Keesje the ATR in Hotel mode is supplied by the same engine driven generators so can supply normally 400A DC.
My 10cents worth.
We fly CHC-WLG vs B737, they pass us in the climb/cruise/descent, but generally we are pulling up on the gate in the ATR about the same time as there passengers are getting up out of there seats. No more that 10mins in it, and pax do prefer the ATR as door to door it is debatable who is quicker, no security checks, quicker boarding and deplaning, and they get a cup of coffee as well.
If Cook get a different type Q400/ATR92, then it will be just as quick if not quicker. As airspace gets more congested for NZ standards, speed control increases and jets on short sectors are only really gaining in the cruise, sometimes in the climb and descent, but if they are above us, there is sometimes not the distance to run to get them thru infront. We can go 250kts to about 8nm final, so we get to catch them up near the end a bit.
Keesje the ATR in Hotel mode is supplied by the same engine driven generators so can supply normally 400A DC.
My 10cents worth.
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By the way the unducted fan (UDF) did actually work and worked quite well.
Might have posted a little bit hasty..
......
Nevertheless ATR believes strongly in this system:
......
Nevertheless ATR believes strongly in this system:
Keesje the ATR in Hotel mode is supplied by the same engine driven generators so can supply normally 400A DC
I think an APU optimized for moving the aircraft around could be equally limited in size and weight. Its doesn't have to produce the bleed air to start up a big turbo fan engine. An serious effort to really reduce noise to a minimum by means of a silencer would add some weight.
Your experience on flying ATR versus 737 on short routes confirms my airline experience. The shorter the flight the less difference between gate to gate times between props & jets. Props are often allowed to use secondary runways too.
This week-end I'll try to summarize & do a Turboliner mark III based on all input
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Can't wait to see the UDF concept.
I firmly believe if you can come up with a M0.75 - M0.77 @ 30,000 UDF you will have a winner - especially if it is rear mounted away from the interference with a super critical wing using a counter rotating design to remove swirl effect. Something along the lines of the GE36 UDF might be workable (although a little small for you as suitable more for the 100-160 seat range) Side benefit is lower cabin noise, high propulsive efficiency and excellent specific fuel consumption.
Might need some good software or access to a wind tunnel for optimum location free of interference/other airframe effects at all AoA.
I am sure your fresh lateral thinking is going to take you a long way.
Cheers.
I firmly believe if you can come up with a M0.75 - M0.77 @ 30,000 UDF you will have a winner - especially if it is rear mounted away from the interference with a super critical wing using a counter rotating design to remove swirl effect. Something along the lines of the GE36 UDF might be workable (although a little small for you as suitable more for the 100-160 seat range) Side benefit is lower cabin noise, high propulsive efficiency and excellent specific fuel consumption.
Might need some good software or access to a wind tunnel for optimum location free of interference/other airframe effects at all AoA.
I am sure your fresh lateral thinking is going to take you a long way.
Cheers.
Last edited by an3_bolt; 4th Apr 2008 at 11:21.
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nothing new yet
All my research and that of my colleagues is published in the leading journals. But you have to buy it. It is not free.
But reasonable. It is a shame you are not using it.
But reasonable. It is a shame you are not using it.
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Regarding the overhead storage, we're always being told what the maximum size is. And with loco's we're being educated that you're a burden for bringing checked baggage. On the third hand, one of the problems with this type of aircraft is that one can board with a carryon-sized item for which there is no longer any space. So my suggestion is, a check-in - side check that one's roller case is the correct size, which gives one a chit for an overhead slot on the aircraft. It doesn't matter when you board, that slot will be there. Those with the random-sized packages get to stuff them below the seat in front. One would receive a boarding pass with a seat number and baggage slot number.
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Refinements & adjustments based on input : Turboliner mark III
Hello folks,
I promised to do an updated mark III based on all your input last week-end. Kids & home improvement caused a small delay. I went through the comments and implemented some suggestions .
Result is the Turboliner Mark III
1. lemurian
Why the leading edge flaps ? The #1 behind the props seem to be both an overkill in terms of aerodynamics, weight and dimensions ( they are also subject to the prop wash). I would have thought that the wing behind the engines will already be in a good lift-generating position.
True I took the Embraer 190 wing as a startingpoint. I removed the leading edge flaps on mark III. Ice protection plates are now situated behind the prop.
2. lemurian
The shoulder wing choice: as a pilot, I've loathed the crosswind susceptibility of airplanes like the Nord 262 or the ATR, because of their narrow landing gear. See the balance of weight savings on a comparison between A/- structural gains in getting away from the project as it is now and B/-the advantages of a low wing, wide landing gear, wing bending moments...etc...
3. low n' slow
Also I feel a little sceptic to the gear/wing configuration. It would feel more sturdy having the gear in the nacelles (Fokker and Dash) instead of the ATR-type placement. A high wing I argue will make the plane more sensitive to strong crosswinds.
I took a long & hard look at gear in the nacelles. To keep the size of the main landing gear within a reasonable envelope it becomes necessary to make the fuselage as flat as possible like on An32, Q400 and F50. This aircraft is meant to replace 737 and A320 on shorter legs. Also leisure / low cost flights where people take a lot of luggage. Doing a Google on Q400 and luggage I found a lot of complaints. It is a major restriction on this aircraft caused by the aircraft cross section. The Turboliner doesn’t have to have cargo container / pallet capability like the A320 and I did flatten the lower fuselage. However it has to have enough space to stow 160 serious bags. This would result in a very long and heavy main landing gear. Also including electric drives on it could create issues. So I decided to stick with the ATR / military style landing gear. I included the Q400 cross section for reference in the drawing.
4. lemurian
Another advantage of the low wing is the easier integration of the airplane with existing airport gates - that will allow you to do away with at least one integrated airstairs, hence a further weight saving.
Having the very large prop would create some ground clearance issues requiring very high main landing gear legs. I did a lot of different studies and in the end concluded a high wing isn't so bad for a prop.
5. lemurian
Lastly, the fuel system would be simpler, with the added possibility of a centre tank.
True for narrowbody aircraft, but they can do flights up to 3000nm. The Turboliner is an uncompromised short haul aircraft, mostly up to 1000nm. I think the long un-interrupted wings would provide enough space for its limited payload range requirements.
6. low n' slow
Make the nose looke a little more like the Saab and less like the Dornier and you're home free!
:-) I see you have a national preference. I drew the nose low to maximize the viewing angle for the pilots. This aircraft is driving over airports a lot during the day.
7. low n' slow
It's all very nice with the electrical tug system, but I feel it will function just as all the other "nice to have capabilities" I have so far seen, and that is occasionally/sporadically. Having complex electronics in an area that will take up a lot of force in everyday operations just doesn't feel sound to me. Reliability and ease of maintenance is very important and any factors compromising this must be taken into consideration.
The assumption is the silent aircraft will be allowed to operate where noise restriction are important. Fuel will be saved by running the APU instead of two engines and not requiring push back tugs.. (less lost slots too I guess..)
8. low n' slow
I also notice you have given the plane speedbrakes similar to the Bae. You would save more just getting rid of them. Remember, it's a turboprop. Not only are they inherrently slow, but they also have a fantastic stopping capability by means of the props... Having liftdumpers/flight spoilers though (Dash) makes a little sense considering manouverability and landing the wing upon touchdown.
9. kiwilad
I agree with a earlier comment about crosswinds, the problem with the ATR is the wing continues to fly to around 40-50kts, spoilers that dump lift on landing would start to solve some of the issues surrounding the interesting crosswind handling techniques.
I removed the speed brakes. I installed a patented (Lockheed) system called DLC (direct lift control). In combination with other control surfaces & black boxes it allows to decent without changing pitch or engine settings. Gliders have something similar and Lockheed used it on the L1011 Tristar. For an high winged aircraft doing steep approaches up to 8 times a day, its seems very useful interms of comfort and limiting noise (no engine thrust variations). During landing they act as additional spoilers.
10. kiwilad
If you do go with the apu, something that you can leave running unattended would be great. As I understand most props with apu's require someone on the flightdeck or at the least in the cabin as they don't have automatic fire extinguisher capabilities. I stand to be corrected.
If it is allowed it should be possible. It is a relative small and high placed APU.
11. kiwilad
Have you dug around for info on the ATR 92 concept that is on the drawing boards at ATR at the moment. The Q400X is another one in concept at the moment. I personally think the ATR concept is better as it will be a clean sheet design, with a gear design similiar to yours.
I could not find sketches, do you have any links?
12. Bushfiva
Regarding the overhead storage, we're always being told what the maximum size is. And with loco's we're being educated that you're a burden for bringing checked baggage. On the third hand, one of the problems with this type of aircraft is that one can board with a carryon-sized item for which there is no longer any space. So my suggestion is, a check-in - side check that one's roller case is the correct size, which gives one a chit for an overhead slot on the aircraft. It doesn't matter when you board, that slot will be there. Those with the random-sized packages get to stuff them below the seat in front. One would receive a boarding pass with a seat number and baggage slot number.
I have experienced this issue with regional jets often. I think the Turboliner offers handluggage space comparable to narrowbody jets (cross section is narrower but rectangular).
13. James (Fleetbuzz)
Some details which become apparent include that the wing box will conflict with the overhead bins. The fuselage cross-section is similar to a typical low wing aircraft and would be slightly different in a high wing aircraft. In a low wing aircraft the cargo bay is the natural location for the wing box to intersect the fuselage. In this high wing aircraft the thin side-walls will not be enough between the wing box and the landing gear and also have a cut-out for an emergency exit at the same time. There is a lot of load in the frames especially in the area between the rear spar and the landing gear.
The wing box may limit headroom unless the wing is located higher on top of the fuselage. High enough to allow headroom, overhead bins, and for a cargo version an unlimited cargo volume. Also the fairing around the landing gear and the wing to fuselage would be much bigger to smoothly cover the box and gear. One benefit of the larger fairing is it allows for structural supports and some system components to be located outside of the fusealge skin under the fairing. External structural features under a fairing are more efficient so the designer will use them whenever possible as soon as the fairing is deep enough to allow them.
I took a look and you seem to be right. I heightened the wing a bit, it comes into the cabin / bins. The fuselage height in the lowest point of the aisle should still be better then 2.1 meters (it's a big cabin for a prop.) Height is about similar to the BAE146 only Turboliner cross section is more rectangular shaped.
14. James
Early design decisions include arranging the structure to allow for a side cargo door and sizing the cabin for standard containers. A swing nose or tail would allow full access to load cargo but may be too complicated. Swing nose/tail has only been used on very specialized aircraft.
I think a conventional side door would be sufficient for typical short haul parcel loads, like the BAE 146 Quiet Trader..
15. James
A high wing may end up with the slight dihedral shown in the illustrations and the vertical stabilizer looks almost big enough to react a one-engine-out yaw. The top of the vertical stabilizer would also need a fairing big enough for the screw to adjust the horizontal stabilizer pitch trim. Also the aft fuselage may be longer/forward fuselage shorter to react the weight of the engines forward of the wing.
The mark II had your concerns covered. I think the place of engines, wing, tail and the fuselage length is pretty accurate. I measured many top views of twin props for reference.Of cause I could have made a spreadsheet estimating all weights & load arms and determine the Lift locations but decided someone else might want to pick up that challenge..
16. James
The wing box may need to be thicker to take the engine loads. Try to avoid the limited life problems seen on the C-130 and P-3; easier said than done. A thicker wing immediately impacts the cruise speed....and many, many other design parameters all of which influence each other.
A thicker wing box has consequences for the aerodynamics high speed performance of the wing. I think it should be a CRFP wingbox. There would be indeed serious loads from the big engines and long fuselage.
17. James
If the overhead windows are to allow light in the cabin to save exectricity for cabin lights, then the windows should be minimal in size and make use of a reflector/diffuser and not make a hole in the fuselage any larger than necessary. Side windows are subjected to pressurization and shear loads, the top of the fuselage also has bending loads in either tension or compression and a large window may have a weight penalty.
I made the drawing a bit clearer, small windows indeed and brackets to take the loads. The 4 overhead windows came in place of 20% / 12 windows deleted in comparison to the A320/737. It is mainly a weight reduction combined with a better space experience / admosphere for people sitting in middle / aisle seats.
18. James
It remains to be seen if the TP400 lives up to it's potential in-service. An excellent engine design that delivers the fuel burn and thrust can still fail if it costs too much to maintain.
The Turboliner should become available years after the A400M enters service. Child deceases could be engineered out of the TP400.
19. James
Composite fuselage?
Personally I have my doubts on CRFP for short haul, airport intense operations. Damage, ramp rash is a fact of live for an aircraft that does 6-8 flights a day.. Also not sure if layered composites and prop resonance go together well..
BTW I adjusted cabin for 6 more seats reducing pitch from 32 to 31 inch. (some low cost airlines I flew do 28 inch
..)
20. James
TP400 implies bleed air.
The TP400 use a microjet as a starter. I hope this could limit the size of the APU and save a lot of piping.
21. James
Props can shed ice of there is usually a reinforced skin next to the props.
Indeed. I included protection plates behind the props like most turbo prop aircraft have.
22. enicalyth
All my research and that of my colleagues is published in the leading journals. But you have to buy it. It is not free. But reasonable. It is a shame you are not using it.
I have no reference, may you could lift a tip of the curtain / provide some keywords?
23. James
A clever design will address the issues with solutions which solve multiple needs at the same time and do it with elegant simplicity. The 777 would not exceed performance specs unless it included very clever design solutions.
I would be interested in hearing any other comments on the design details implied by this configuration. The details help clarify the accuracy of the overall performance analysis so as to avoid overestimating.
Agreed, any comments / ideas are welcome!
I promised to do an updated mark III based on all your input last week-end. Kids & home improvement caused a small delay. I went through the comments and implemented some suggestions .
Result is the Turboliner Mark III
1. lemurian
Why the leading edge flaps ? The #1 behind the props seem to be both an overkill in terms of aerodynamics, weight and dimensions ( they are also subject to the prop wash). I would have thought that the wing behind the engines will already be in a good lift-generating position.
True I took the Embraer 190 wing as a startingpoint. I removed the leading edge flaps on mark III. Ice protection plates are now situated behind the prop.
2. lemurian
The shoulder wing choice: as a pilot, I've loathed the crosswind susceptibility of airplanes like the Nord 262 or the ATR, because of their narrow landing gear. See the balance of weight savings on a comparison between A/- structural gains in getting away from the project as it is now and B/-the advantages of a low wing, wide landing gear, wing bending moments...etc...
3. low n' slow
Also I feel a little sceptic to the gear/wing configuration. It would feel more sturdy having the gear in the nacelles (Fokker and Dash) instead of the ATR-type placement. A high wing I argue will make the plane more sensitive to strong crosswinds.
I took a long & hard look at gear in the nacelles. To keep the size of the main landing gear within a reasonable envelope it becomes necessary to make the fuselage as flat as possible like on An32, Q400 and F50. This aircraft is meant to replace 737 and A320 on shorter legs. Also leisure / low cost flights where people take a lot of luggage. Doing a Google on Q400 and luggage I found a lot of complaints. It is a major restriction on this aircraft caused by the aircraft cross section. The Turboliner doesn’t have to have cargo container / pallet capability like the A320 and I did flatten the lower fuselage. However it has to have enough space to stow 160 serious bags. This would result in a very long and heavy main landing gear. Also including electric drives on it could create issues. So I decided to stick with the ATR / military style landing gear. I included the Q400 cross section for reference in the drawing.
4. lemurian
Another advantage of the low wing is the easier integration of the airplane with existing airport gates - that will allow you to do away with at least one integrated airstairs, hence a further weight saving.
Having the very large prop would create some ground clearance issues requiring very high main landing gear legs. I did a lot of different studies and in the end concluded a high wing isn't so bad for a prop.
5. lemurian
Lastly, the fuel system would be simpler, with the added possibility of a centre tank.
True for narrowbody aircraft, but they can do flights up to 3000nm. The Turboliner is an uncompromised short haul aircraft, mostly up to 1000nm. I think the long un-interrupted wings would provide enough space for its limited payload range requirements.
6. low n' slow
Make the nose looke a little more like the Saab and less like the Dornier and you're home free!
:-) I see you have a national preference. I drew the nose low to maximize the viewing angle for the pilots. This aircraft is driving over airports a lot during the day.
7. low n' slow
It's all very nice with the electrical tug system, but I feel it will function just as all the other "nice to have capabilities" I have so far seen, and that is occasionally/sporadically. Having complex electronics in an area that will take up a lot of force in everyday operations just doesn't feel sound to me. Reliability and ease of maintenance is very important and any factors compromising this must be taken into consideration.
The assumption is the silent aircraft will be allowed to operate where noise restriction are important. Fuel will be saved by running the APU instead of two engines and not requiring push back tugs.. (less lost slots too I guess..)
8. low n' slow
I also notice you have given the plane speedbrakes similar to the Bae. You would save more just getting rid of them. Remember, it's a turboprop. Not only are they inherrently slow, but they also have a fantastic stopping capability by means of the props... Having liftdumpers/flight spoilers though (Dash) makes a little sense considering manouverability and landing the wing upon touchdown.
9. kiwilad
I agree with a earlier comment about crosswinds, the problem with the ATR is the wing continues to fly to around 40-50kts, spoilers that dump lift on landing would start to solve some of the issues surrounding the interesting crosswind handling techniques.
I removed the speed brakes. I installed a patented (Lockheed) system called DLC (direct lift control). In combination with other control surfaces & black boxes it allows to decent without changing pitch or engine settings. Gliders have something similar and Lockheed used it on the L1011 Tristar. For an high winged aircraft doing steep approaches up to 8 times a day, its seems very useful interms of comfort and limiting noise (no engine thrust variations). During landing they act as additional spoilers.
10. kiwilad
If you do go with the apu, something that you can leave running unattended would be great. As I understand most props with apu's require someone on the flightdeck or at the least in the cabin as they don't have automatic fire extinguisher capabilities. I stand to be corrected.
If it is allowed it should be possible. It is a relative small and high placed APU.
11. kiwilad
Have you dug around for info on the ATR 92 concept that is on the drawing boards at ATR at the moment. The Q400X is another one in concept at the moment. I personally think the ATR concept is better as it will be a clean sheet design, with a gear design similiar to yours.
I could not find sketches, do you have any links?
12. Bushfiva
Regarding the overhead storage, we're always being told what the maximum size is. And with loco's we're being educated that you're a burden for bringing checked baggage. On the third hand, one of the problems with this type of aircraft is that one can board with a carryon-sized item for which there is no longer any space. So my suggestion is, a check-in - side check that one's roller case is the correct size, which gives one a chit for an overhead slot on the aircraft. It doesn't matter when you board, that slot will be there. Those with the random-sized packages get to stuff them below the seat in front. One would receive a boarding pass with a seat number and baggage slot number.
I have experienced this issue with regional jets often. I think the Turboliner offers handluggage space comparable to narrowbody jets (cross section is narrower but rectangular).
13. James (Fleetbuzz)
Some details which become apparent include that the wing box will conflict with the overhead bins. The fuselage cross-section is similar to a typical low wing aircraft and would be slightly different in a high wing aircraft. In a low wing aircraft the cargo bay is the natural location for the wing box to intersect the fuselage. In this high wing aircraft the thin side-walls will not be enough between the wing box and the landing gear and also have a cut-out for an emergency exit at the same time. There is a lot of load in the frames especially in the area between the rear spar and the landing gear.
The wing box may limit headroom unless the wing is located higher on top of the fuselage. High enough to allow headroom, overhead bins, and for a cargo version an unlimited cargo volume. Also the fairing around the landing gear and the wing to fuselage would be much bigger to smoothly cover the box and gear. One benefit of the larger fairing is it allows for structural supports and some system components to be located outside of the fusealge skin under the fairing. External structural features under a fairing are more efficient so the designer will use them whenever possible as soon as the fairing is deep enough to allow them.
I took a look and you seem to be right. I heightened the wing a bit, it comes into the cabin / bins. The fuselage height in the lowest point of the aisle should still be better then 2.1 meters (it's a big cabin for a prop.) Height is about similar to the BAE146 only Turboliner cross section is more rectangular shaped.
14. James
Early design decisions include arranging the structure to allow for a side cargo door and sizing the cabin for standard containers. A swing nose or tail would allow full access to load cargo but may be too complicated. Swing nose/tail has only been used on very specialized aircraft.
I think a conventional side door would be sufficient for typical short haul parcel loads, like the BAE 146 Quiet Trader..
15. James
A high wing may end up with the slight dihedral shown in the illustrations and the vertical stabilizer looks almost big enough to react a one-engine-out yaw. The top of the vertical stabilizer would also need a fairing big enough for the screw to adjust the horizontal stabilizer pitch trim. Also the aft fuselage may be longer/forward fuselage shorter to react the weight of the engines forward of the wing.
The mark II had your concerns covered. I think the place of engines, wing, tail and the fuselage length is pretty accurate. I measured many top views of twin props for reference.Of cause I could have made a spreadsheet estimating all weights & load arms and determine the Lift locations but decided someone else might want to pick up that challenge..
16. James
The wing box may need to be thicker to take the engine loads. Try to avoid the limited life problems seen on the C-130 and P-3; easier said than done. A thicker wing immediately impacts the cruise speed....and many, many other design parameters all of which influence each other.
A thicker wing box has consequences for the aerodynamics high speed performance of the wing. I think it should be a CRFP wingbox. There would be indeed serious loads from the big engines and long fuselage.
17. James
If the overhead windows are to allow light in the cabin to save exectricity for cabin lights, then the windows should be minimal in size and make use of a reflector/diffuser and not make a hole in the fuselage any larger than necessary. Side windows are subjected to pressurization and shear loads, the top of the fuselage also has bending loads in either tension or compression and a large window may have a weight penalty.
I made the drawing a bit clearer, small windows indeed and brackets to take the loads. The 4 overhead windows came in place of 20% / 12 windows deleted in comparison to the A320/737. It is mainly a weight reduction combined with a better space experience / admosphere for people sitting in middle / aisle seats.
18. James
It remains to be seen if the TP400 lives up to it's potential in-service. An excellent engine design that delivers the fuel burn and thrust can still fail if it costs too much to maintain.
The Turboliner should become available years after the A400M enters service. Child deceases could be engineered out of the TP400.
19. James
Composite fuselage?
Personally I have my doubts on CRFP for short haul, airport intense operations. Damage, ramp rash is a fact of live for an aircraft that does 6-8 flights a day.. Also not sure if layered composites and prop resonance go together well..
BTW I adjusted cabin for 6 more seats reducing pitch from 32 to 31 inch. (some low cost airlines I flew do 28 inch
..)20. James
TP400 implies bleed air.
The TP400 use a microjet as a starter. I hope this could limit the size of the APU and save a lot of piping.
21. James
Props can shed ice of there is usually a reinforced skin next to the props.
Indeed. I included protection plates behind the props like most turbo prop aircraft have.
22. enicalyth
All my research and that of my colleagues is published in the leading journals. But you have to buy it. It is not free. But reasonable. It is a shame you are not using it.
I have no reference, may you could lift a tip of the curtain / provide some keywords?
23. James
A clever design will address the issues with solutions which solve multiple needs at the same time and do it with elegant simplicity. The 777 would not exceed performance specs unless it included very clever design solutions.
I would be interested in hearing any other comments on the design details implied by this configuration. The details help clarify the accuracy of the overall performance analysis so as to avoid overestimating.
Agreed, any comments / ideas are welcome!
Last edited by keesje; 11th Apr 2008 at 20:23. Reason: spelling / extra info
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Excellent work
I am a believer in the future of turboprops.
The theory of "turboprop avoidance" is sheer myth. Besides, people will fly any equipment, provided it meets their schedule, price and preferably DIRECT routing. Recently in Toronto, Porter has been a booming success!
Only turboprops have the economics to do this task going forward. Jets, like RJs have had to get bigger and bigger to maintain economic leverage. Turboprops, with a slight speed push, can replace jets on many routes. You only have to look at Horizon canceling CRJ00 orders in lieu of Q400s, Luxair refleeting their EMB145s with Q series...ATR can't accomplish this as they don't have the scoot of the Q400.
So, I love the highspeed high cap concept you have. I agree you'd need to push over M.7 tho..the P3 has a max of 400kts, and the Q400 is only 360, you should hop up the speed on this.
Also, pax HATE entering the AC from the rear and it reduces the chance of boarding with Jetways.
As far as bringing IN teh engines...bad call. By bringing the props close to the fuse, you're inviting a larger blade pass vibration as the blade tip shockwaves won't have time to abate. Keep them away from the fuse or you'll end up with a noisy shakey fuse. IMOHO
Anyway, this look alot more than just a hobby to you...where'd you do your design training?
The theory of "turboprop avoidance" is sheer myth. Besides, people will fly any equipment, provided it meets their schedule, price and preferably DIRECT routing. Recently in Toronto, Porter has been a booming success!
Only turboprops have the economics to do this task going forward. Jets, like RJs have had to get bigger and bigger to maintain economic leverage. Turboprops, with a slight speed push, can replace jets on many routes. You only have to look at Horizon canceling CRJ00 orders in lieu of Q400s, Luxair refleeting their EMB145s with Q series...ATR can't accomplish this as they don't have the scoot of the Q400.
So, I love the highspeed high cap concept you have. I agree you'd need to push over M.7 tho..the P3 has a max of 400kts, and the Q400 is only 360, you should hop up the speed on this.
Also, pax HATE entering the AC from the rear and it reduces the chance of boarding with Jetways.
As far as bringing IN teh engines...bad call
. By bringing the props close to the fuse, you're inviting a larger blade pass vibration as the blade tip shockwaves won't have time to abate. Keep them away from the fuse or you'll end up with a noisy shakey fuse. IMOHOAnyway, this look alot more than just a hobby to you...where'd you do your design training?