You mentiond the protection plates behind the props for ice. As James mentioned previously, you may also need the reinforce the skin of the fuselage to protect from ice impact.

As seen in this image: http://www.airliners.net/photo/Banco-de-Mexico/De-Havilland-Canada/1364184/M/

keesje

Your design idea has a fuselage diameter & length and wingspan almost identical to an A320 -- but its empty weight is 35% lower!

Where will your design save the 15 tonnes? Seems particularly difficult since the T-tail and high-wing/low-gear arrangements are heavier.

CFM56's weigh about 2400kg each, TP400's about 1900kg each, so there's a ton of savings per airframe. 14 to go!

Hi Machada,

the Turboliner and A320 share the same seat capasity, but that's about all.

Thw A320 is a heavy aircraft for short haul passenger service.

The MTOW of the Turboliner is much lower because it is not a medium haul aircraft like the A320.

The Turboliner would have significantly less then half the range / fuel capasity. (1500nm vs 3200 nm)

No serious cargo capability is foresee, contrary to A320 which has containers/pallet capability and loading system.

Turboliner wings, tail section and floor should be CRFP like all modern designs but unlike the A320.

The fuselage cross section would be narrower then A320, 3.7 m vs 3.95 m. Turboliner fuselage & cabin are closer to the BA146.

The service ceiling of the Turboliner would be around 25.000ft vs 40.000ft and max speed are lower influencing the pressure cabin / structure weight.

Lighter galleys (no ovens) just small meals, less lavatories etc, no IFE, etc.

Basicly everything is lighter because its a dedicated passenger short range turboprop without the medium haul flexibility (& MTOW) the A320 and 737 offer.

I would like to think that ovens and IFE would be in the offering as the market takes a turn downwards, the airlines are looking toward better product offerings rather than just cheap seats. they are still offering cheap seats but are now looking at adding IFE etc to ensure that what market share is available they get the maximum out of it.
Air NZ is just re-fitting the A320 & B767 fleets with IFE in the seat backs. I was surprised that they ordered the A320 without it?!?
As this technology gets lighter and lighter it maybe able to be used with out a major weight penalty.

The Atr 72 MTOW is 22800kgs that we fly and the Q400 is closer to 29t, for a difference of about 6-10seats.

Will be interesting to finally see what ATR offers as a 90seat turbo-prop concept. Also hear that Embraer are talking/planning a 90seat turbo-prop as well. So I would guess that the current fuel price issues may be the start of a very strong push toward turbo-prop flying.

Soon our fleet will be getting upgraded/replaced and the contenders were the ATR600, Q400 and ERJ190. The 600 and 400 were most likely with a view to the 90seat products ATR and DASH are looking at building, one a stretch of a old technology the other off a clean sheet with all new technology available.

My money would be on keeping the ATR!!

But wouldn't mind if they bought your turbo-prop keesje:ok:

kiwilad
 

It would seem Bombardier could use the new CSeries 5 abreast fuselage and many systems as a starting point. They did the same with the Q and CRJ series. C110 fuselage / cabin:

http://www.bombardier.com/en/3_0/3_8/img/C110_LOPAs.gif

A new wing & tail would be neccesary (althoung Embraer plans to use the E190's wing for the above mentioned high winged C-390)

Also good news from the engines front new heavy turbo shafts : GE38-1B (7500 hp), Honeywell a new T55 version : 55-L-71X (>5000 hp) and Rolls keeps improving the AE2100 (max 5000 hp).

GE plots GE38 engine's future in emerging heavylift market

I'm not too sure what you are getting at here, but there's no real design commonality between the dash 8 and CRJ fuselages. The dash started development long before Bombardier/Canadair had any involvement in Downview, and the CRJ fuselage of course is a direct development of the Challenger. So there's no common ancestor to the designs.

Keesje - I'm unclear on your response to my question regarding weight:

They share the same physics and math too.

Yes, I agree the A320 is a bit heavy for max efficiency short-haul pax service. So how do you carry the same # of pax with 14 tonnes less airplane?

Certainly. However, I asked about OEW.

This is mostly determined by wing volume available for the fuel tanks and powerplant fuel burn.

I don't agree with your cargo market evaluation, but for the sake of it let's dispense with the pallet/container sytems. OK, that'll save 1.5 more tonnes. 12.5 to go!

So what are the calculated weight savings due to use of CFRP? The A320 is already 28% composites by weight, including the entire tail structure. The A380 saved almost 15 tonnes by the use of composites, including a CFRP wing center wing box and entire tail structure - that shaved its OEW by 5% to 277 tonnes!

Why? Your OEW kg per seat is lower than a Cessna 172!How much weight does this shed and from where - fuselage skin thickness?

OK, galleys just like a Q400 & ATR-72 (can't cut the lavs or pax will spend entire flight in the queue!). So how does the Turboliner get to be so much lighter?

I really like the idea of a 150 seat twin TP-400 powered airliner, but more hard numbers are needed to assess its feasibility.

Machaca
 

Thanks for the good look you took at the number

I don't think we have to go to deep for that one.

I took some data from a nice MIT study of the various relevant efficiencies influencing overall efficiency for different aircraft & propulsion types.

Report by Raffi Babikian, Stephen P. Lukachko and Ian A. Waitz can be found at: http://web.mit.edu/aeroastro/people/...s/Babikian.pdf, 2003?

http://i191.photobucket.com/albums/z...g?t=1214911705

As can be seen in the graph Turboprop engines tend to be 15-20% more fuel efficient then turbofans. main driver of this is the very high BPR of over 1:30. The engines used on 737 and A320 (CFM56 / V2500) are improved versions of 20-30 year old designs, the limited BPR is only 1:5. The TP400 with the latest technology build into a blank paper design is probably closer or even over 20%. SFC probably around around .4

As you mentioned Turboprops are also structurally more efficient then jet aircraft. This has to do with their limited flight envelope and dedicated short haul passenger design.

http://i191.photobucket.com/albums/z...g?t=1214911991

This structural efficiency results in lower weights and lift induced drag. Taxiing efficiency is also much better for high frequency operations. Other efficiencies are of a lower order. These considerations made me conclude a 25 % more fuel efficient operation should be possible with the Propliner compared to e.g. a similar sized 737 or A320.

Question arises why it hasn't been tried earlier. I think fuel was a smaller part of total operating costs. Increased speed (=frequencies) and medium range flexibility were more important. Nobody felt the need to develop a higher BPR engine like open rotor or real big turboprop.

Keesje
How about wading into the shallow part and providing some basic answers? How will you shed the weight? This is the Tech forum, not the brochure-speak dream forum.

No you didn't. You extrapolated wildly from a graph to guesstimate a desired outcome.

The graph represents aircraft, not engines. I asked about airframe weight, not BPR.

How did you derive such a claim?

I mentioned no such thing. Short haul aircraft are structurally reinforced to handle their high cycle operating environment. This adds weight.

The MIT study you linked to contradicts your statement:Time to reconsider what conclusions are possible!

Keesje, there are many highly experienced and knowledgeable aviation professionals willing to contribute meaningfully to your idea if you are willing to engage in a honest dialogue.

Machaca
 

Machaca, excuse if I angered you, if I appeared dishonest> I did not intend to avoid basic answers!

As I mentioned in earlier posts (#6) I did not take the B737 or A320 as a starting point. I took the BAE146 family (fuselage) and TP400 engine (MTOW) as starting points. As you can see in the first post the Turboliner shares the tail, landing gear and general wing configuration. If we look at the last biggest ever BAE146 variant, the RXJ100, it has an empty weight of about 25.450kg (56,108lb). The max 120 seat Fokker 100 is a tonne lighter.

http://cdn-www.airliners.net/aviatio.../0/0240073.jpg
This photo no doubt creates sad feeling for UK readers.. sorry, the only RJX100. Specs: http://www.airliners.net/aircraft-data/stats.main?id=48

The RJX has a 1500 kg lower OEW then the Turboliner. The RJX basic airframe & wing were developed about 35 years ago.

Taking the RXJ1000 & TP400 as a starting point (as I did: http://i191.photobucket.com/albums/z...g?t=1214997582 ).

• Replacing the 4 engined BAE 146 wing with a new CRFP wing with 2 engines will save weight. : 1500 kg?
• Replacing the the RXJ's Al tail with a CRFP one will save weight 1000 kg?
• Replacing floor and floor beams and torsionbox with CRFP : 1000 kg?
• The Turboliner has less range, max speed, lower ceiling : xxx kg?

That leaves ~5000kg for the 6 meters fuselage stretch (2 plugs) and seats / cabin and other adjustments that come with it. Not an unreasonable estimation I think.

Maybe I'm optimistic and the OEW is higher. An OEW close to the A320 as you suggest would be to high IMO. I don't think its like comparing a SUV to a compact car, but the designs have different missions for sure. ;)

kind regards,
keesje

RR talking up 150 seater with TP400 !
 

Rolls-Royce promotes turboprop solution for new civil airliners

:ok:

And I bet they've been looking at your thread, or are you connected with them?

But this is the engine manufacturer looking at the possibility of increasing the market for it's product. They do mention that they haven't spoke to the airframe producers yet. I suspect those companies have some drawings for aircraft similar to yours. But I suspect the reason they haven't come to light is that it's just not yet viable. With oil heading for $200, it may just yet.

The A320/B737 designs have evolved from a design concept which fits the current market requirements. Your high capacity TP design looks like it is trying to justify it's design by stealing the business from the current designs. But it's going to have to fill a niche, and I don't think the market is quite ready to change just yet. But who knows what the air travel market will be like in 10 years time.




Just one point about the reduced size cargo holds. A lot of routes need freight business to stay profitable. I fly A320s around China and we nearly always have at least 2 tonnes of freight in the holds.

Interesting thought - when does a turboprop become an open rotor / unducted fan and vice versa?

Dan
 

No, I've never had anything to do with RR.

I think the strenght of the A320 is that it is able to load cargo containers and a full passenger load and fly it over medium distances like in the Chinese market. But it is also the reason that it is relatively heavy / overpowered for short trips. On short trips cargo is less important. Door to door trucks / didicated transport chains in populated areas are hard to beat for the shorters sectors the Turboliner would serve.

I tried to dimension the cargohold to be just big enough to handle the luggage for a full load of holiday travellers. Lowering the floor created room for big luggage bins enabling more hand luggage for short haul / day business trips to e.g. LCY.

No that's not the intent. The intent is to provide a feasible low risk way to reduce fuel costs by at least 20% in the important 150 segment. Airlines are begging for that. :{

Airbus and Boeing have enormous backlogs and are in no hurry, saying breakthroughs are neccessary that can not be done before 2020. :hmm:

Quote: I tried to dimension the cargohold to be just big enough to handle the luggage for a full load of holiday travellers. Lowering the floor created room for big luggage bins enabling more hand luggage for short haul / day business trips to e.g. LCY.

Then the design is going to be restricted in it's use. You are consigning it to a limited market. I don't think it would fit in the Asian market, which is the biggest emerging market at the moment and can't be ignored by any manufacturer.

Dan
 

Yes, that's basicly the trick. One aircraft that can do it all is an inherent compromise. On shorter distances (e.g Europe) you pay a high price for this flexibility. With fuel prices approaching 35% of total airline costs it is becoming no longer acceptable for the operators.

The NB market is so big dedicated types for various markets will probably be a smarter solution. So no 1-1 replacement, but a split. In the narrowbody market we allready see the Superjet, CSeries, Embraer 190/195, ARJ pushing out the heavy 737-600-700 and A318/319 where the payload range capasity of those types is not needed.

http://gc.kls2.com/cgi-bin/gcmap?RAN...NGE-COLOR=navy

1200 NM ranges from MIA, JFK, AMS, DXB and PVG.

Luckely people live together in populated areas. Even in China most traffic is concentrated around the East Coast. Ghuanzou is little more then 1000nm away from PEK. Inbetween most activity seems concentrated. A320/737s could take care of longer / cargo included flights.

Sorry, but thats becomes more and more the basic problem.


Even with a perfect aircraft, short flights are bad for business. On the one hand, there are a lot of other means of transport, on the other hand, a lot of costs of a flight accumulate per flight/per cycle and not per flight hour (e.g. landing fees, maintenance costs). The limit of 1500NM is leaving only a small spectrum of ranges, where airlines earn money. Take a look at the BAe146 and the lack of range and the lack of success of this aircraft.


A smaller and very light airframe could be the first step to a more fuel efficient aircraft. But while the whole aviation world is talking about the fuel price, airlines are paying leasing rates (or interests), spendig a lot of money for maintenance, paying fees and give money to the crew.

Saving 500kg fuel from LHR to AMS woud be great, but if the other costs are to high, you can't sell even one Turboliner.

Again, here arrives the weight at the scene. You want to offer a short range aircraft, which is flying thousands of cycles (round about 100.000 cycles in 30 years ?!). And the weight is lower than anything known today. This could work, but the mechanicians would have to change a lot of structural parts during the life cycle. In this case, the maintenance costs would hit the roof.

Take the average structure weight of some comparable modern aircrafts (320/737) and subtract 10%. This would be more serious than scaling up from a very special kind of aircraft like the BAe146.

MadDogFlyer
 

Of course saving any 500 kg would be great, however that's not the situation on short haul >120 seat operations at this moment.

A ~120 seat Boeing 737-600 weighs empty : 80,031 lb (36,378 kg), A318 more.
A ~110 seat Fokker 100 weighs empty : 53,510 lb (24,272 kg)

Difference in OEW is 30% or 12.000 kg. That's the same as the payload weight of the 120 passengers + their luggage.

1500NM easily covers the 700 million Europeans and 800 millions Chinese living on the East coast and more then a billion people from Delhi.

IMO Aircraft made for short haul operations are all significantly lighter then 737/A320. Thing is aircraft like the BAE146, F100, 737-100, DC9 and BAC One-Eleven where never replaced. Bigger aircraft offered more payload / range flexibility & fuel prices weren't a real issue (in the sense that it killed airlines).

I have the feeling Bombardier with its lighter dedicated more fuel efficient 110-130 seater will have a ball next week and in the coming years.. ATR is looking at stepping in too with a 100 seat prop. ATR refers to new turboprop study as '-900'. At this moment Embraer is king of the hill. Airlines simply had no alternative during the last 10 years.

http://www.skycontrol.net/UserFiles/...be-08_alta.jpg

True. Knowing in advance the aircraft will be used shorthaul, high frequency would be a design requirement. On the other hand giving in at range, payload, ceiling and speed would make everything lighter, aslo the structural loads. Adding metal in the places where it should be is a matter of good design, as well as e.g. good accessibility for inspection & repair.

hiya

I see madog's point but I also think that at this stage it would be interesting to know why the F100 is so much lighter than the B737-600.

On balance I think you are on to a goos thing keesje, but I am going to throw a few spanners.

My most basic question is why you are using such a conventional layout when there is a layout that rather clearly is a very good fuel saver and is happily competing with jets in it's field: the Piaggio Avanti II.

Details for the config are here: Showcase

25% better than a normal turboprop sounds too good to miss if you are planning to compete on fuel cost. Scaling could get interesting, but the Avanti is not that unknown an aircraft anymore. And I am sure Piaggio could be persuaded to a joint venture.

The other problem I have is that as a passenger I have a severe dislike of the BAe 146 in 6 abreast layout. I once sat in a row with 2 other big guys and we actually had to tile our shoulder in order to fit! I consider 737-width to be the bar minimum. What I am wondering is why you are not using an ovoid fuselage such as the A350 in order to make more space?

On a very basic level I'd also say that the income from freight is so significant that that rather makes the space for it worthwhile.

Other points from this discussion:

- I would support a ceiling of at least FL320 or so to be able to avoid the weather.

- Speed: 380 kts or so I am thinking. For the jet proponents:

SAS are already flying slower with their jets in order to save fuel:

SAS flies slower to save costs and emissions | Environment | Reuters

So I would not think that that is any kind of criterium for these kind of flights.

Overall I love this idea and am looking forward to the further development of this. I have also seen the posts on airliners.net

cheers

Bernhard

What's the noise target of the Turboliner? In the 1990's Saab promised 76dB to Crossair but achieved only 78 dB, much to Crossair's annoyance.

Sunho