Jump to content

Twin Otter Extended Preview (FSX,P3D)


Mathijs Kok

Recommended Posts

  • Replies 1.9k
  • Created
  • Last Reply

Very few aircraft can make me feel Giddy like a little school girl. Tee heee !!! :bow_down2_s:

You said it, bro! Especially us, caribbean, island-hopping fans. We were thankful enough as it were to have the first version. Flew beautifully. Now this! Superior modelling! Awesome!!

Link to post
Share on other sites

just three questions abaut the real twinotter

a chalange for readers!

Q1 what is the max takeoff weight of the twinotter if it was an expierimentel aircraft?

Q2 how much weight can the twinotter wing handle befor it stops creating lift?

Q3 what speed is the true max for the airframe and wing of the aircraft?

chad hittenberger

Link to post
Share on other sites

This info comes straight from Viking Aircraft in Victoria, B.C. They have the Twin Otter type certificates now, Chad.

GENERAL INFORMATION:

Max. Takeoff Weight:

12,500 lbs. (5,670 kg.)

Max. Landing Weight:

12,300 lbs. (5,579 kg.)

Number of Crew: 1 or 2

Number of Passengers: 19

Fuel Capacities:

Total – 378 US Gallons (1,432 litres)

Optional Long Range – 89 US Gallons

(336 litres

PERFORMANCE SUMMARY:

STOL Takeoff and Landing Distance

Takeoff distance to 50 ft.: 1,200 ft (366 m)

Landing distance from 50 ft.: 1,050 ft (320 m)

Maximum Cruise Speeds, TAS

Sea Level: 170 kt

5,000 ft.: 181 kt

10,000 ft.: 182 kt

Enroute Rate of Climb at Sea Level

(both engines at max. climb power):

1,600 ft./min

Service Ceiling (Rate of climb 100 ft/min)

(both engines at max. climb power):

25,000 ft. (7,620 m)

Fuel Burn at Economy Cruise

146 KTAS at 10,000 ft.:

468.2 lbs/hour (0.311 nm/lb of fuel)

Payload Range – at max cruise speed

Payload for 100 nautical mile (185 km) range:

4,061 lbs. (1,842 kg.)

Payload for 400 nautical mile (741 km) range:

3,031 lbs. (1,375 kg.)

Maximum Range (Zero Payload)

With standard tankage (2,576 lbs. (1,169 kg.) fuel):

799 nm (1,480 km)

With long range tankage (3,190 lbs. (1,447 kg.) fuel):

989 nm (1,832 km)

Maximum Endurance

With standard tankage (2,590 lbs. (1,175 kg.) fuel):

6.94 hrs.

With long range tankage (3,190 lbs. (1,447 kg.) fuel):

8.76 hrs.

Link to post
Share on other sites

these are the certifid specs what i want to know is could you takeoff at higher weights i think it could but they did not spend the money to test that theory they derated the engines so that the full 750 shp could be used only on takeoff that is not cool with me. they should have put the p&w pt6a140a on the airplane it is an 867shp engine.+2 engines =1734hp high power twinotter.

chadhittenberger

Link to post
Share on other sites

these are the certifid specs what i want to know is could you takeoff at higher weights i think it could but they did not spend the money to test that theory they derated the engines so that the full 750 shp could be used only on takeoff that is not cool with me. they should have put the p&w pt6a140a on the airplane it is an 867shp engine.+2 engines =1734hp high power twinotter.

chadhittenberger

Well with that power there would be a little weight increase if the engines were the same size, the only gains mostly would be climb and "Hot and High operations". The wings, Wing roots and struts only have so much strength. As for speed, the huge straight wings are not desinged to go fast, they are more for lift. The way Vicking aircraft adds more usefull weight to the -400 series is to lighten the plane with carbon fiber in some areas as well as lighter doors and other improvements.

Link to post
Share on other sites

There are a number of issues at play when designing an aircraft, such as role and operating costs. In this case, the Twotter is designed for relatively short flights into short semi prepared runways. For an operator, you want a reasonable payload and the operating costs are such that it is possible to make money. The engines are derated because you actually reduce the operating costs not only in fuel used but it also reduces the wear and tear on the engine thus preserving its working life. As for weights, it is not necessarily a case of what the wing can lift but as the weight in the airframe increases, you have to strengthen the wing roots and the wing/fuselage joins otherwise the weight of the aircraft will be too much and the wing will break at the root. Furthermore, you may have to strengthen the undercarriage. All this adds weight and increasing the shp doesn't necessarily give you the same economics. So the increased weight, both empty and payload, in a small aircraft such as the twotter does not necessarily increase the revenue capability of the aircraft because of the increased costs associated to higher fuel burn and a likely reduction in range. Another consideration is performance, such as runway length needed for Tkoff and Ldg, single engine performace at max weight, and engine performance at the different weights at different temperatures and altitude.

Just my two bits worth to the discussion

Craig

Link to post
Share on other sites

Craig hit on a lot of excellent points but out of the original questions, Q2 is fundamentally flawed. Weight does not affect how much lift a wing can produce - weight only changes how much lift a wing MUST produce. It will never stop producing lift because of weight but may enter a stall trying to produce enough lift to compensate for weight if that is what you asking.

The amount of lift a wing generates relates to speed and angle of attack for airflow and pressure differential. There is of course a given envelope for both aspects with in which the wing must operate to continue producing lift. To high an angle of attack or too little airspeed to generate sufficient airflow and the wing will stall. Of course it is a combination of the two that induces a stall because angle of attack must be increased to compensate for lack of airspeed.

I think what you really want to know is how much lift does the Twin Otter wing produce at Vne at max angle of attack and for that one I don't have an answer for but you would be hard pressed to get into that part of the envelope anyway...

Link to post
Share on other sites

IGrant. Good points. I thought about going into aerodynamics but you covered it very nicely.

One additional point would be that if the aircraft is too heavy on takeoff, it probaby wouldnt get airborne because it can't obtain sufficient speed to generate enough lift.

Interesting topic though :D

Link to post
Share on other sites

my next Question is if viking has the production certificate why didn't they bring the plane 100% into the 21st century with a 787 style efis panel with fadec,boeing style yokes,electronic nose wheel steering,carbon fiber divider between the cabin and the cockpit. the 867 shp non derated engines are for the float version not the wheeled one.the last statement i want to make is that the strat floats should have rudders on them because opposing thrust steering is to difficult in close quarters.

chad hittenberger

Link to post
Share on other sites

most probably cost. You have to remember that the companies who buy this aircraft are not large. The more complicated you make the aircraft the higher the purchase price, the higher the running cost and the more highly trained your maintenance team has to be. Remember this aircraft's general role is so it has to be rugged and need very little support.

Link to post
Share on other sites

Well I for one am waiting on this. the last version was excellent this can only be better. As for fancy cockpits, I dread the day, the GPS system looses a few milliseconds in timing, and all of a sudden all the new generation pilts are lost because they cant read a compass. I still fly mostly VFR, that way I know where I am and dont need to be told where I should be.

Still waiting, but im patient.

Link to post
Share on other sites

Chad: Remember that avionics are more than just what displays you can fit into the panel. There are a lot more components that aren't seen like AHRS, sensors, wiring and more. If you open up the nose on something like say a 1990's Citation with a minimum of EFIS, there are still A LOT of avionic components in there taking up space, power and cooling. It also comes down to cost and application. Mach hold would be silly in a plane that will never reach .50 for example so it doesn't justify the cost. It is definitely a case of more than meets the eye.

Craig: Definitely interesting! I enjoy aerodynamics and was quite happy when I saw this topic being discussed. I think the only caveat is when you have a grossly over powered aircraft like something in the aerobatics category that can literally hover because of the power to weight ratio. At that point though, the wing has been completely taken out of the equation. It does turn into a cascading list of problems though: The wing can generate the lift if there is speed. New, more powerful engines can generate the speed but now we need to props to put that power to use. New props (if they aren't too big) can generate the thrust needed to attain the potential speed but now the wings just get ripped off... and so on. And on a semi-related note, the power to results ratio is not linear but actually exponential. I was reading some where about trying to make a Dodge Viper go faster and with a 1000hp engine, they would have to add another 500hp to see anymore appreciable speed gains because they just needed that much more power to push the car through the air any faster because of built up resistance.

So in light of all that, I for one, and perfectly happy with the standard Twin Otter that Aerosoft are producing!

Link to post
Share on other sites

how much difference does the glass cockpit make in the weight of the aircraft in the current generation aircraft, then the old steam gades like in the aerosoft twin otter. Why did viking go with the old yokes and control system instead of a more modern one more like the boeing 737 original series then they could have moved the throttles to a floor center pedestal between the pilots, the radios right beside the pilots behind the throttles like modern airliners.

chad hittenberger

Link to post
Share on other sites

hi guys,

did any twin otters ever have a apu in them?

is this model windows 7/8 compatible?

mathijs please have a correctly operating load manager with the extended version because the current one does not work right it does not interface with flight sim at all. thus the weight and balance is not correctly doeble realistically pleas make this one more interactive with flight sim.

chadhittenberger

Link to post
Share on other sites

Chad

Depends what you select as your glass cockpit.

Viking were probably happy to leave the flight controls as they were. Having the throttles in the overhead requiures less wire to the engines and saves a little weight. Another reason could be that because the aircraft were designed for remote, semi prepared surfaces, there is a greater chance of debris to be caught in throttle, pitch or mixture linkages causing them to stick. The throttles were in the overhead for the caribou (DH4) and the I think also for the Buffalo.

As far as I am aware, the twotter never had an apu. They use a ground cart or batteries to start. In reality it doesnt need one because the electrics don't draw that much current and it's not air conditioned like a commuter turboprop or jetliner.

Craig

Link to post
Share on other sites
  • Root Admin

most probably cost. You have to remember that the companies who buy this aircraft are not large. The more complicated you make the aircraft the higher the purchase price, the higher the running cost and the more highly trained your maintenance team has to be. Remember this aircraft's general role is so it has to be rugged and need very little support.

And it has been shown a few times that glass cockpit and rough landing are not a good mix. I believe Viking had it's problems with that.

Link to post
Share on other sites

Derated engine discussion: Whether you know it or not, the same principles apply to modern automotive design. For instance, the 2.0L turbo in my car produces about 200bhp. That same engine in other applications by the same manufacturer produces close to 300bhp, and with some relatively minor modifications is capable of producing much more. The factory derates for various reasons; more than 250bhp may not be appropriate for a front drive application, but is perfectly acceptable in a rear, or awd vehicle. It may also allow the factory to charge more for what is basically the same technology. Of course, I could go down and get an ecu reflash tomorrow and add 50bhp just like that. The price paid would be reduced durability, fuel economy, and possibly driveability. Aircraft engine manufacturers derate for many of the same reasons.

As far as putting a more "modern" type cockpit into the Twotter: Remember that Viking is re-certifying an existing aircraft, not building a new one. There are some very restrictive rules imposed by various national aviation authorities when it comes to redesigning an aircraft. Costs tend to escalate rapidly with this process. Something seemingly simple like moving the throttles to a pedestal could be a shockingly expensive proposition. In addition to finding room for cables, wires, and mechanical components, Viking would have to prove that their new cockpit is more reliable than the old (certification standards have become stricter since the Twotter was first certified). This would lead to a more drawn out and much more expensive flight test program. And for what? The current system has been around a long time and proven reliable. Viking decided it could drop some weight and add some capability by introducing a basic glass instrument panel. My guess is that the benefits of doing this barely outweighed the costs. They would be silly to make any major changes to the plane that didn't significantly add to a potential operator's profit. A 787 panel certianly wouldn't have done so.

Aerosoft's version: The Twotter is a somewhat iconic aircraft with a LOT of character. In choosing the versions it has, I think Aerosoft is going to capture as much of that character as is possible with a joystic and a 22" LCD screen. This sentiment is further confirmed for me by the fact that Aerosoft have put such a great team to work on this plane. I haven't touched FS in a couple months as I haven't really found anything to get too excited about lately. Not that there haven't been some great releases, but I fly complex airplanes for a living and don't really have the time to properly learn the excellent FS airliners (there's a new DC-9 that's really been tempting me though). The Twotter will be just about my perfect FS aircraft. Complex enough to be interesting, good for IFR or VFR, medium or short hops, It will be the perfect distraction from life at 370.

Link to post
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Guest
This topic is now closed to further replies.



×
×
  • Create New...