acjbbj
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(Theoretical) re-engine of An-225

Sat Apr 14, 2018 1:48 am

If the An-225 were to get new engines that are more efficient than the current D-18T's, which one of today's engines would be suitable?

Could it use four larger engines instead of the six? I'm imagining four Trent 895/Trent XWB-97, GE90-94B/upsized GEnx, or PW4090/4098 or something based on the PW1000G series.

Six Trent 560's could work, but I feel like I've posted too much about the A340 in too short of a time period.

Ideally, it would use two engines, but getting a 690-750 kN engine working? I doubt. Too big, too wide, too heavy, and too much drag.

Any thoughts?

I know it's gonna need a major design change, and it's gonna involve new wings and new engine control systems, etc. It's gonna be expensive. I would just like to see what your thoughts are, so please don't say "it's not possible", "it's too expensive", "what are you thinking", etc. I would just like to know what engines you think could be used on an An-225 with four engines.
Favourite plane: "L-1011-800 TriStar Next Generation" :mrgreen:
(3-Engine cargo jet approximately the size of a 77F, with three Trent XWB-97. Two engines on the wing, the third in the tail with an S-duct.)
 
hitower3
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Re: (Theoretical) re-engine of An-225

Sat Apr 14, 2018 9:17 am

Technically, there are many points to consider - including the vastly different interface architecture between D18T's and any western FADEC powerplant. Next is the issue around wing load balancing. Next is the whole certification stuff around performance, engine out procedures etc. And the list of potential issues is likely much longer.
Economically, things are very clear: if you need the An225, you will be ready to pay the price for it. The variable cost would be somewhat (2000USD? 3000USD?) lower by using modern engines, but this is more than offset by the whole development and certification cost (several 100 million USD?) that needs to be absorbed by one or two aircraft flying very low hours.

In short: makes no sense.

best regards,
Hendric
 
stratclub
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Re: (Theoretical) re-engine of An-225

Sat Apr 14, 2018 9:45 am

The real deal breaker is the age of the airframe. 30 years? Aging Aircraft Maintenance will throw any thoughts of economical operation out the window. And then a 1 of ? Even if all the outcomes were good, a 1 of would make zero economic sense especially with the age of the airframe.

New wings? Why? New Pylons with needed structural modification to the wings would work. It's not like we are asking the wings to do anything it didn't do before.
 
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Re: (Theoretical) re-engine of An-225

Sat Apr 14, 2018 10:12 am

I think the cheapest option would be to go with the six engines. With six you are still left with 5 if one goes down. With four, you are left with three and considerably less power by ratio and a high chunk of power lost if one goes down.

I don't see a current modern engine on the market that could service this aircraft - once the MOM comes to fruition, then we could see something that would work. Possibly a scaled PW1100G up UltraFan or something along those lines but the prosepct as you know it zero.
 
WIederling
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Re: (Theoretical) re-engine of An-225

Sat Apr 14, 2018 10:49 am

acjbbj wrote:
If the An-225 were to get new engines that are more efficient than the current D-18T's, which one of today's engines would be suitable?


The D-18T has
sealevel tsfc of .36 ( lb/lbf/h )
in cruise tsfc is .57 ( lb/lbf/h )

compare to Trent 7000 with
cruise tsfc of 0.506 lb/lbf/h

That is just 12% more fuel for a frame that does not show
the utilization profile to make fuel a significant expenditure.
It is not unduly short legged either.

If you want to do something about tsfc you'd probably be better
served with an engine PIP to the D-18T.
Murphy is an optimist
 
jetblueguy22
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Re: (Theoretical) re-engine of An-225

Sat Apr 14, 2018 5:17 pm

Be willing to bet if you need the services of the AN-225, cost isn't really a factor.
Look at sweatpants guy. This is a 90 million dollar aircraft, not a Tallahassee strip club
 
VSMUT
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Re: (Theoretical) re-engine of An-225

Sun Apr 15, 2018 2:02 pm

Btblue wrote:
I think the cheapest option would be to go with the six engines. With six you are still left with 5 if one goes down. With four, you are left with three and considerably less power by ratio and a high chunk of power lost if one goes down.


I would agree with this. The engine out requirements are just as valid on the An-225 as they are on the A340 and 777. Having fewer engines means that you have to limit your potential payload more. It's the exact same reason why 777s can struggle on hot and high airports, while the "underpowered" A340 can handle the same airports with few issues.

You would also have to solve the wing bending issue once you remove several tons of engine from the wings.
 
acjbbj
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Re: (Theoretical) re-engine of An-225

Sun Apr 15, 2018 6:39 pm

So, aside from Trent 560's maybe (six) CF6's or Trent 700/7000?
Favourite plane: "L-1011-800 TriStar Next Generation" :mrgreen:
(3-Engine cargo jet approximately the size of a 77F, with three Trent XWB-97. Two engines on the wing, the third in the tail with an S-duct.)
 
WIederling
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Re: (Theoretical) re-engine of An-225

Sun Apr 15, 2018 8:47 pm

acjbbj wrote:
So, aside from Trent 560's maybe (six) CF6's or Trent 700/7000?


Why change to an engine that has similar tsfc?
Murphy is an optimist
 
gtae07
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Re: (Theoretical) re-engine of An-225

Mon Apr 16, 2018 12:44 am

You'd never make back the cost of the conversion. Why bother?
 
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LA704
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Re: (Theoretical) re-engine of An-225

Mon Apr 16, 2018 9:57 pm

A GENx-2B would be the closest thing among the newer engines IMHO.
One could dream about gearing up a LEAP (different companies, I know) to get the thrust and spectacular TSFC...
Thirdly the russian military could decide to order some new, updated 225s with 6 upsized PD-14 engines.
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Re: (Theoretical) re-engine of An-225

Tue Apr 17, 2018 10:30 am

LA704 wrote:
A GENx-2B would be the closest thing among the newer engines IMHO.
One could dream about gearing up a LEAP (different companies, I know) to get the thrust and spectacular TSFC...
Thirdly the russian military could decide to order some new, updated 225s with 6 upsized PD-14 engines.


Following Russia's invasion against Ukraine in 2014, Antonov will refuse their orders for An-225, with or without imagined derivatives of the (incredibly overhyped) PD-14 program.

(On the engines, just to make things clear, there seems to be a great much noise in the engine building circles in Russia, about PD-14. There seem to be three pro-PD-14 factions: 1) sings that PD-14 is the next best thing since the sliced bread, and Russia should finance its development ASAP, with unlimited budget; 2) agrees with (1) but adds that all other available resources have to be thrown into building a smaller, de-rated derivative, with approximately 7 ton thrust (cough... SSJ ... cough); 3) agrees with (1) but insists on urgency of building an up-rated larger derivative, to power everything else in sight.

Of course, there is a fourth faction, insisting that the whole PD-14 story is a diversion, instigated by Russia's enemies, whose purpose is to kill the glorious PS-90 family.)
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neutrino
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Re: (Theoretical) re-engine of An-225

Tue Apr 17, 2018 2:17 pm

Phosphorus wrote:
Following Russia's invasion against Ukraine in 2014, Antonov will refuse their orders for An-225, with or without imagined derivatives of the (incredibly overhyped) PD-14 program.

If there's any resumption of An-225 production, its going to be made in China. Dependent on the details and fruition of the plans between Antonov and the Middle Kingdom of course.
Potestatem obscuri lateris nescitis
 
VSMUT
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Re: (Theoretical) re-engine of An-225

Tue Apr 17, 2018 9:51 pm

Phosphorus wrote:
LA704 wrote:
A GENx-2B would be the closest thing among the newer engines IMHO.
One could dream about gearing up a LEAP (different companies, I know) to get the thrust and spectacular TSFC...
Thirdly the russian military could decide to order some new, updated 225s with 6 upsized PD-14 engines.


Following Russia's invasion against Ukraine in 2014, Antonov will refuse their orders for An-225, with or without imagined derivatives of the (incredibly overhyped) PD-14 program.


If the Russians really had som massive need for a unique one-off airlifter, they would just build it at the Aviastar facility in Ulyanovsk, where half the An-124s were built. They have all the blueprints and know-how anyway.
 
strfyr51
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Re: (Theoretical) re-engine of An-225

Tue May 15, 2018 9:50 pm

acjbbj wrote:
If the An-225 were to get new engines that are more efficient than the current D-18T's, which one of today's engines would be suitable?

Could it use four larger engines instead of the six? I'm imagining four Trent 895/Trent XWB-97, GE90-94B/upsized GEnx, or PW4090/4098 or something based on the PW1000G series.

Six Trent 560's could work, but I feel like I've posted too much about the A340 in too short of a time period.

Ideally, it would use two engines, but getting a 690-750 kN engine working? I doubt. Too big, too wide, too heavy, and too much drag.

Any thoughts?

I know it's gonna need a major design change, and it's gonna involve new wings and new engine control systems, etc. It's gonna be expensive. I would just like to see what your thoughts are, so please don't say "it's not possible", "it's too expensive", "what are you thinking", etc. I would just like to know what engines you think could be used on an An-225 with four engines.


I THEY used the PW, GE or Rolls engines They would be beholden to the west. And the integration technology that comes with installing the engines.
They have NO intention of releasing that technology anytime soon as a LOT of it is owned by Boeing. This would include the FADEC engine controls.
 
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Re: (Theoretical) re-engine of An-225

Fri May 25, 2018 6:24 pm

VSMUT wrote:
Phosphorus wrote:
LA704 wrote:
A GENx-2B would be the closest thing among the newer engines IMHO.
One could dream about gearing up a LEAP (different companies, I know) to get the thrust and spectacular TSFC...
Thirdly the russian military could decide to order some new, updated 225s with 6 upsized PD-14 engines.


Following Russia's invasion against Ukraine in 2014, Antonov will refuse their orders for An-225, with or without imagined derivatives of the (incredibly overhyped) PD-14 program.


If the Russians really had som massive need for a unique one-off airlifter, they would just build it at the Aviastar facility in Ulyanovsk, where half the An-124s were built. They have all the blueprints and know-how anyway.

Do they have all the blueprints? I hear conflicting details. The breakup of the Soviet Union was messy.
You only have the first amendment with the 2nd. If you're not going to offend someone with what you say, you don't have the 1st.
 
VSMUT
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Re: (Theoretical) re-engine of An-225

Sat May 26, 2018 2:24 pm

lightsaber wrote:
VSMUT wrote:
Phosphorus wrote:

Following Russia's invasion against Ukraine in 2014, Antonov will refuse their orders for An-225, with or without imagined derivatives of the (incredibly overhyped) PD-14 program.


If the Russians really had som massive need for a unique one-off airlifter, they would just build it at the Aviastar facility in Ulyanovsk, where half the An-124s were built. They have all the blueprints and know-how anyway.

Do they have all the blueprints? I hear conflicting details. The breakup of the Soviet Union was messy.


With 99.99% certainty they kept copies of everything in Moscow, especially for high-value technical projects like aircraft. The breakup of the USSR wasn't messy in that way. It wasn't like the DDR where the people raided the Stasi archives. The archives of the aviation authorities, design offices and test and development centres like TSAAGI should remain intact.
 
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Matt6461
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Re: (Theoretical) re-engine of An-225

Mon May 28, 2018 10:21 am

WIederling wrote:
acjbbj wrote:
If the An-225 were to get new engines that are more efficient than the current D-18T's, which one of today's engines would be suitable?


The D-18T has
sealevel tsfc of .36 ( lb/lbf/h )
in cruise tsfc is .57 ( lb/lbf/h )

compare to Trent 7000 with
cruise tsfc of 0.506 lb/lbf/h

That is just 12% more fuel for a frame that does not show
the utilization profile to make fuel a significant expenditure.
It is not unduly short legged either.

If you want to do something about tsfc you'd probably be better
served with an engine PIP to the D-18T.


What's your source for D18 SFC?
That's a surprisingly good figure for an older Russian engine.
 
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Matt6461
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Re: (Theoretical) re-engine of An-225

Mon May 28, 2018 10:44 am

On reflection, the T7000 - D18 cruise SFC figures are probably apples-oranges: An225 cruises at ~.73M so there's less ram drag for D18 at the specified cruise. T7000's figure would be lower than listed for a slower cruise, but the engine would be off-optimum if not adapted to the platform (and it wouldn't be possible to perfectly adapt it).

Wiederling gives a -11% SFC delta for T7000 over D18, which imply Soviet parity with the best versions of the CF6. D18's topline numbers for OPR and BPR are competitive with CF6 but it seems unlikely the component efficiencies were similar.

I'd guess An225 could see something approaching 20% SFC delta with a re-engine. That'd be cool and very useful for its operator but of course not warranted by the economics.

But maybe when/if China restarts production it'll just dump a pile of cash into a re-engine for pride's sake .
 
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Matt6461
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Re: (Theoretical) re-engine of An-225

Mon May 28, 2018 12:19 pm

Just to play around with this idea a little more:

acjbbj wrote:
Could it use four larger engines instead of the six?


As a matter of physics, yes. And given existing engine options, that would be the most attractive route.
The issue would be how much modification the wings would require for the altered load/bending characteristics and whether such modifications would be feasible within the current wing (to stay within remote feasibility, let's assume no new wing).
Every NEO/MAX project has involved alterations of this general type, though not involving the removal of engines. Let's just say it's possible and then look at thrust requirements.

For one-engine-inoperative (OEI) conditions, our quad An225 would require something approaching current OEI thrust, but not quite as much. That means higher total thrust: more than the current 6 * 51,600lbs = 306,400lbs.
We need not quite as much OEI thrust as current 5-engine thrust because our higher total thrust means that, on an equal takeoff run at equal MTOW, we're going faster at a given distance down the runway. Faster speed (V2 is the critical speed for OEI) means higher L/D, which means less drag, which means less thrust needed to maintain an acceptable OEI climb rate.
I'd guess that ~330,000lbs total thrust would be adequate to retain field performance: ~8% higher total thrust and ~4% less OEI thrust. Takeoff L/D increases roughly with the square of speed, which increases roughly with the square root of total thrust for a given field length. That rough relationship roughly matches our OEI thrust and drag deltas.
That means four ~82k engines - just about perfect for TXWB, with room to grow if we need more OEI thrust.

Per Ivchenko-Progress, the newest version of D-18T has .546 SFC at cruise. http://ivchenko-progress.com/wp-content ... d18s34.pdf That's probably several % better than the older engines fitted to An225.

As I said above, we have to "penalize" the D-18T's SFC figure for its slower cruise on An-124/225. A linear penalty for .75M versus .85M would escalate its SFC to ~.64, but we know there's a propulsive efficiency benefit to higher cruise speed (lower specific thrust from lower exhaust overspeed). That effect doesn't dominate the ram drag SFC impact of course... Idk how to quantify the effect but I'll just stick with a -20% SFC guess for D-18T --> TWXB delta. That's in line with .6X speed-normalized SFC for D-18 and low .5's SFC for TXWB.

What about the weight/drag of four TXWB's?
D-18T is a ~9,400lbs dry, TXWB-84 is ~16,000lbs. So there's a net ~7,600lbs delta for engine dry weight.
We're losing a pair of pylons, however, and those Antonov pylons are awfully large (anyone know why? Did they not master managing wing/engine interference effects very well, requiring greater vertical separation?). All-in, after accounting for nacelles and fuel system (piping etc.), the OEW delta probably wouldn't exceed 10,000lbs?
The wetted area of four TXWB's would probably exceed that of six D-18's (can't find physical dimensions, any sources?), but again we're losing a big pylon so overall drag effect shouldn't be impactful.

Meanwhile, any restart of production and re-engine would involve moving from the current H tail to a normal tail or T-tail. The current tail is built that way because the Soviet space shuttle would have interfered with the V-stab. Moving to a normal/T-tail would likely save thousands of pounds in empennage weight, so overall OEW delta would be close to neutral. You'd need a little more tail volume for OEI conditions given our greater thrust imbalance but that's much easier to implement via a normal empennage than with the current layout.

So I could see a re-engined quad An-225 with TXWB engines having about the same L/D and OEW, with ~20% lower SFC. Again, that's assuming the wing can be adapted to the new load paths.

That means ~25% greater range for a given payload, which puts the An-225 in striking distance of a 200t TATL load, which would be pretty awesome.
 
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Channex757
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Re: (Theoretical) re-engine of An-225

Mon May 28, 2018 1:35 pm

Aviadvigatel PD-35.

Russia's new 77,000lb turbofan is in development and can be scaled to the required size. It's an 8 tonne and 120 inch diameter stab at the Trent/GEnx market for the CRAIC C929.
 
acjbbj
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Re: (Theoretical) re-engine of An-225

Tue May 29, 2018 3:38 am

Just ]to note, the way the An-225's pylons are designed (long and big, engines are mounted low) prevents (or at least reduces) loss of control in case an engine reverses thrust in flight. Someone pointed out somewhere else that the engines on "today's" planes being mounted so high up (almost in front of the wing) make them extremely vulnerable to crashing if reversers come on in flight. Keep the big pylons. You're flying in the air with a 180,000 kg load, and one of your engines reverses thrust, and your engine pylon is today's short and stubby design? Disaster.

Had you kept the longer pylons, you would probably still have control.
Favourite plane: "L-1011-800 TriStar Next Generation" :mrgreen:
(3-Engine cargo jet approximately the size of a 77F, with three Trent XWB-97. Two engines on the wing, the third in the tail with an S-duct.)
 
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Matt6461
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Re: (Theoretical) re-engine of An-225

Tue May 29, 2018 8:34 pm

acjbbj wrote:
Just ]to note, the way the An-225's pylons are designed (long and big, engines are mounted low) prevents (or at least reduces) loss of control in case an engine reverses thrust in flight. Someone pointed out somewhere else that the engines on "today's" planes being mounted so high up (almost in front of the wing) make them extremely vulnerable to crashing if reversers come on in flight. Keep the big pylons. You're flying in the air with a 180,000 kg load, and one of your engines reverses thrust, and your engine pylon is today's short and stubby design? Disaster.

Had you kept the longer pylons, you would probably still have control.


Seems like there are better ways to address this. You're proposing a big aero penalty for the chance of surviving something that should never happen in the first place.

I also question the extent of pylon impact on control retention during reverser activation. The critical moment is rotational, not on the horizontal plane. I'm sure I'm missing some subtle effect but the forest is yaw, a few trees of pitch moment don't fundamentally change the picture.
 
WIederling
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Re: (Theoretical) re-engine of An-225

Wed May 30, 2018 12:40 pm

Matt6461 wrote:
What's your source for D18 SFC?
That's a surprisingly good figure for an older Russian engine.

caveat: Afair: and unsorted:
https://books.google.de/books?id=_5vA_5 ... fc&f=false
http://www.motorsich.com/eng/products/a ... /tde/d-18t
https://www.flightglobal.com/FlightPDFA ... 202250.PDF
http://www.buran-energia.com/mriya-anto ... -carac.php

the google book link has both sealevel and cruise tsfc.
kgf/h*kg_fuel and lbf/h*lb_fuel is equivalent. ( units force/weight units cross out )
Murphy is an optimist
 
acjbbj
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Re: (Theoretical) re-engine of An-225

Wed May 30, 2018 1:45 pm

I meant that the blast created by in-flight reversal with the An-225's current pylon design goes mostly under the wing. But today's pylons are so much shorter and the engines are up higher which means that now a lot of the blast now goes over the wing. Therefore you will enter an uncontrolled dive and you're dead.
Favourite plane: "L-1011-800 TriStar Next Generation" :mrgreen:
(3-Engine cargo jet approximately the size of a 77F, with three Trent XWB-97. Two engines on the wing, the third in the tail with an S-duct.)
 
WIederling
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Re: (Theoretical) re-engine of An-225

Wed May 30, 2018 5:51 pm

acjbbj wrote:
I meant that the blast created by in-flight reversal with the An-225's current pylon design goes mostly under the wing. But today's pylons are so much shorter and the engines are up higher which means that now a lot of the blast now goes over the wing. Therefore you will enter an uncontrolled dive and you're dead.


why would you do "short pylons" on a high wing aircraft!?

Engine displacement relative the wing ( forward, downward ) is a function of installation limitations.
Not dependent on the current rage :-)
Murphy is an optimist
 
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Matt6461
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Re: (Theoretical) re-engine of An-225

Wed May 30, 2018 6:37 pm

Wiederling wrote:
why would you do "short pylons" on a high wing aircraft!?


Because objects moving through a fluid create drag in rough proportion to their size. https://en.wikipedia.org/wiki/Parasitic_drag
 
WIederling
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Re: (Theoretical) re-engine of An-225

Wed May 30, 2018 6:56 pm

Matt6461 wrote:
Wiederling wrote:
why would you do "short pylons" on a high wing aircraft!?


Because objects moving through a fluid create drag in rough proportion to their size. https://en.wikipedia.org/wiki/Parasitic_drag


probably a minor issue vs. the perfect position relative the wing.
you want to optimize on ‰ effects while squandering performance in the % range?
Murphy is an optimist
 
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Matt6461
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Re: (Theoretical) re-engine of An-225

Wed May 30, 2018 6:59 pm

WIederling wrote:
Matt6461 wrote:
Wiederling wrote:
why would you do "short pylons" on a high wing aircraft!?


Because objects moving through a fluid create drag in rough proportion to their size. https://en.wikipedia.org/wiki/Parasitic_drag


probably a minor issue vs. the perfect position relative the wing.
you want to optimize on ‰ effects while squandering performance in the % range?


You've posted in the past about induced drag being separate from L/D analysis and about winglets only impacting airflow around wingtips. So I don't exactly trust your conclusion that the Swet contribution of an engine pylon is minor relative to airflow disruption over the wing.

In any event, you asked for a reason to do X, I gave such a reason. Where the cost/benefit of smaller pylons falls out is another issue.

And it's besides my main point in the TXWB analysis post: It's not so much that we'd shrink pylons, but that by going from 6 to 4 engines we'd remove one pylon pair entirely. And, by the way, the removed pylons are large. Even you, I suspect, will recognize that removing a pylon - whatever its size - is optimal when it is no longer attached to an engine.
 
WIederling
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Re: (Theoretical) re-engine of An-225

Thu May 31, 2018 10:16 am

Matt6461 wrote:
So I don't exactly trust your conclusion that the Swet contribution of an engine pylon is minor relative to airflow disruption over the wing.


The lawyer pushing through?
Scientific observation is not dependent on trust but on reason. ( That was the big intellectual step taken at the time. )
Murphy is an optimist

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