PPRuNe Forums

PPRuNe Forums (https://www.pprune.org/)
-   African Aviation (https://www.pprune.org/african-aviation-37/)
-   -   Brand New Twotters (https://www.pprune.org/african-aviation/269831-brand-new-twotters.html)

Fat Reggie 28th Mar 2007 04:56

Brand New Twotters
 
Looks like its going to happen. New Twin Otters with -34 engines manufactured by Viking Aircraft.

http://www.vikingair.com/content.aspx?id=320

$3.2 mil a copy for the new dash 400 Twotter. Thats 60 lbs of Tq on the dial and MUCH better hot & high performance.

To hell with junk, I want New.

Solid Rust Twotter 28th Mar 2007 08:24

Have the operators expressed enough interest and made the deposits required to make the new Twotters a worthwhile project for Viking and are they finally going ahead?

Edited to add:- Can't see that G1000 panel lasting long in the tougher areas of operation. At least the old steam instruments were reasonably bulletproof and capable of getting through a week or two of abuse at a time without input from an engineer. It'll be great for the commuters, though...:ok:

B Sousa 28th Mar 2007 15:15

Remember , never fly an A model of anything........

V1... Ooops 28th Mar 2007 21:56

No, it won't be 60 torque on the dial. The -34 engines have been chosen because the -27s are out of production - the -34 is the only small PT6 still in production, thus the only engine available as new/zero time.

The flat rating will continue at 620 SHP, same as horsepower remains flat rated at 620 SHP on existing series 300 Twin Otters that have been retrofitted with -34 engines by STC. The horsepower limitation is an aerodynamic issue - the fin and rudder are not large enough to handle an asymmetry greater than 620 hp. This is why the -27 engine, which has a thermodynamic rating of 680 hp (equal to 53.3 pounds of torque) was flat-rated down to 620 at the start of series 300 production almost 40 years ago. You will note that the series 300 aircraft have the same size fin and rudder as the original series 100, which was equipped with 550 horsepower -21 engines. Rudder travel was increased on the series 300 and additional vortex generators were added to the fin (above the horizontal stabiliser), but the greatest asymmetry that the engineering flight test team could accept was 620 hp - hence that red line at 50 torque that we all know so well.

Trust me on this one, I was there in Victoria at the operators' conference when the Series 400 was announced last September, and there were lots of questions about this exact issue posed to the Viking engineering staff by the attendees at the conference.

V1... Ooops 28th Mar 2007 22:02


Originally Posted by Solid Rust Twotter
Have the operators expressed enough interest and made the deposits required to make the new Twotters a worthwhile project for Viking and are they finally going ahead?

We were told at the conference in September 2006 that a final go / no-go decision would be made during the first half of 2007. Viking is very well financed, very solidly backed, so if sufficient deposits can be converted into firm orders and the overall economics look good, there is no reason to prevent them from going ahead with the project.

The key issue, of course, is how many operators are willing to ante up three an a half large for a new Twin Otter. For non-commercial operators who need the specialty capabilities of the aircraft (e.g. governments, military, oil industry, research), the capital cost is not a significant issue - it's half the price of a new King Air. For commercial operators who charter the aircraft out by the hour or on an ACMI basis, the cap cost is a fairly big pill to swallow.

V1... Ooops 28th Mar 2007 22:11


Originally Posted by Solid Rust Twotter
Can't see that G1000 panel lasting long in the tougher areas of operation.

On the contrary, as far back as the early 1990s, bush operators such as Merpati in Indonesia (a VFR only operation) were retrofitting first generation glass cockpits (Collins displays) precisely because these displays had far lower MTBF (mean time between failures) and far lower costs of ownership than conventional electro-mechanical instruments. In the late 90s, I worked for an operator that retrofitted 12 Twin Otters with dual Garmin 430 stacks to replace the original com/nav units. They bought 3 additional 430s to keep as line spares, and to the best of my knowledge, these three are still in the store in the original shrink-wrap.

The Garmin 1000 panel is well proven now - it's basic equipment on everything from Cessna 172s to the new Cessna Mustang Jet. The system architecture is very straightforward - when you release a couple of fasteners and tilt the panel aft (it is hinged at the bottom), you see a rack of LRUs (Line Replaceable Units). As for the display itself - it is substantially the same as a high quality notebook computer display. That is certainly 'tough enough'. The display can be replaced with a new one, if needed, in about 15 minutes. The replacement cost (cost of a whole new display screen) is less than what it costs to ship a conventional electro-mechanical AI or HSI out of Africa to where it can be repaired, and ship it back again.

Solid Rust Twotter 29th Mar 2007 05:55

Howdy Mike, good gen. Ta muchly.

Still a bit suspicious of this noofangled electronic skullduggery and would prefer steam for basic engine and flight instruments. Know the G430 well and had no probs with it so far but not sure chucking the entire dash into a single display gives enough redundancy for the grottier ops. Fine for the softer machines like C206, L410 and such:E that don't really get about much, but reckon the mighty Twotter deserves something more bulletproof.

Fat Reggie 29th Mar 2007 13:45

I don't think 3.2 mil is to much for a new twotter. Sounds darn resonable to me. There is certainly a demand for this type. Is the demand enough to start production? I don't know, but rumor has it...yes. Though we all know that twotter rumors are lengendary. Whats a new Pilatus Porter cost and where do they get their new -27 engines? (price including oar locks please)

Solid Rust Twotter 29th Mar 2007 14:03

What new -27 engines are these of which you speak, Earthling? Heard they're out of production, hence the switch to -34s for the new Twotter. (Unless those cunning Swiss have a warehouse full of -27s stashed somewhere.)

Spoke to a driver who'd been flying one with a -34 upgrade and he said the same thing. 50 psi torques max but better hot and high performance and torque remained high up to an increased altitude. Sounds like a bargain to me...:ok:

Sir Osis of the river 29th Mar 2007 16:19

Instruments
 
Must say that I would side with SRT on the choice of instruments in a Twotter. Some of the places I've taken them and seen other people take them are not suited to modern Electrics.

It might suit some airline type operations like Merpati, Lesotho in the old days, or even sightseers in the Grand Canyon who most probably have ongoing daily maintanence.

However your average bush operator in Africa, maybe except Zimex, does not have an engineer on sight, let alone an avionics specialist. Day in and day out operating on dusty, bumpy and muddy conditions will take their toll with thje a/c only seeing an engineer maybe once a month.

Add to that, flying tons of maize in leaking bags, (Man, that fine dust gets into everything), high humididty, etc and I figure it wont be too long before you are flying partial panel.

(That all said, I do agree that your average African operator would be unlikely to be able to afford the sticker price of a new one)

Fat Reggie 30th Mar 2007 05:36

I better do some deeper checking. Some dummy told me 60 Tq and I bought it. I'm sceptical of a glass cockpit in the bush. Better to go with what you know I'd say...unless you want to risk money for experimenting. As for weight, there are a couple of different MTGW ups of a thousand pounds if you have the thick skinned wings. I wonder if Viking is going to up the weight limit? (not so sure it would be such a good idea for the bush) The wing hard point mod for external stores in interesting. Might get something besides a relief work contract with that mod, say something that pays $3000+ a flight hour maybe?

V1... Ooops 31st Mar 2007 02:26

Contemporary flat panel avionics are bulletproof - far, far more reliable than any electro-mechanical instrument could ever be.

Think of it in this context: Have you ever seen a Garmin 430 or 530 that has failed? Not likely, and Garmin has sold over 80,000 of those pieces of kit now. I use a Garmin 496 aviation portable on my motorcycle, leave it out in the rain, toss it in the saddlebag, never had any problems. Even the satellite antenna (the round XM antenna for the real-time meteo information) sits out in the rain on one side of the handlebars. The larger Garmin systems such as the G-1000 are just evolutions of the same technology.

I think that when many of us consider the question of glass displays in remote operations, we think of the first generation of displays that came out in the late 1980s and early 1990s. We are way, way ahead of that now.

Given a choice between contemporary 'glass' avionics and electro-mechanical for bush operations, I'd take glass every time without a moment of hesitation.

V1... Ooops 31st Mar 2007 02:35


Originally Posted by Fat Reggie
there are a couple of different MTGW ups of a thousand pounds if you have the thick skinned wings. I wonder if Viking is going to up the weight limit?

The MTOW increase to either 14,500 lbs (for wheel operations) or 15,000 lbs (for water bombing operations, on floats) is accomplished by way of an engineering order. de Havilland only made that E.O. available to military customers (for the wheel configuration) or to government operators (e.g. state registered aircraft) for the water bombing operations.

There is no intent at all to look at any kind of approval for weights over 12,500 lbs. That would move the aircraft out of FAR 23 and into a different category for both aircraft certification and crew certification, and there's no upside benefit to the manufacturer to go down that route.

The military operators don't have to be concerned about weight because they have no concerns about civil regulations - they can do whatever they want to do. de Havilland didn't certify those military aircraft for operations over 12,500 - they just incorporated the E.O., sold the aircraft to the military customer, and wished them a good day. As for the water bombers - they work on the understanding that if you encounter any problems, you just push a little button on the yoke, and 4 seconds later, instead of weighing 15,000 lbs, you now weigh 9,000 lbs. There are a whole bunch of other issues involved - wing life is reduced, wing tip tanks must be kept full to reduce wing bending moments, etc., but there is really no point in getting into that.

I.R.PIRATE 31st Mar 2007 09:11

I am also for steam driven instrumentation in the bush, but for a slightly different reason.

IF your G1000 packs up when out in the sticks, there is no one that has ever seen something like that, let alone worked on it.

For steam gauges there are always 'mechanics' and loaner units.

Another thing I love about steam is the fact it it is not driven by electrical power.

Woof etc 31st Mar 2007 09:42

Beats me why someone doesn't come up with a clean sheet design in this category. (17-19 seat twin turbo-prop). There seems to be a ready market for this type of aircraft but few contenders.

Solid Rust Twotter 31st Mar 2007 15:25

You can't beat perfection...:ok:

AT502B 31st Mar 2007 16:12

Small pt-6's in production
 
V1 Quote:"The -34 engines have been chosen because the -27s are out of production - the -34 is the only small PT6 still in production, thus the only engine available as new/zero time."

Thats not exactly true, in the ag-flying business the are 3 small pt-6's in production the PT6-11 (550shp), PT6-15 (680shp) and the PT6-34 (750shp). These are available from Pratt brand new in a crate. There is also the PT6-145 they put in the Piper Meridian which is 5-600shp if I remember correctly.

Very_Low_and_Fast 1st Apr 2007 08:43

9 hrs endurance?
 
Is Viking going to remove "9 hrs endurance" from the web page??
"Maximum Endurance
with Standard Tankage (2583 lb (1172 kg) fuel): 7 hr 10 min
with Long Range Tankage (3190 lb (1447 kg) fuel): 9 hr"

Or is the fuel flow going to be half what is it now?

:}

Very_Low_and_Fast 1st Apr 2007 08:58

for Osis
 
"However your average bush operator in Africa, maybe except Zimex, does not have an engineer on sight, let alone an avionics specialist. Day in and day out operating on dusty, bumpy and muddy conditions will take their toll with thje a/c only seeing an engineer maybe once a month."

Osis,
Have you heard of ANY other company in Africa flying Twotters??

:rolleyes:

Sir Osis of the river 1st Apr 2007 09:18

out of touch
 
Low and Fast,

Your handle suggests that you dont fly twotters:confused:

I must admit I am now a bit out of touch with the contract scene, so was not refering to specific operators, but rather the operation of Twotters in unfriendly environments.

In the good old days Rossair had a few, MAF had in Angola, the Marion brothers had at least one in Kinshasa and I recall seein a few in West Africa.

What the present status is, I have no idea?:cool:


All times are GMT. The time now is 23:08.


Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.