Why is the AH-64d so slow?

[v2tec]

For me it seems, that the ka-50 is much faster than the apache.

Most of the time I can fly 300 km/h w/o problems (~161 kts) with the ka-50 but the highest speed with the apache was ~124 kts (~229 km/h). According to some tech sheets on the internet, the helis should have very similiar ias values.

[bies]

This is 1990s Ka-50 variant. 2000s Ka-52 is slower, heavier, less maneuverable.

Contrary we have 2000s AH-64D. Original Cold War/Desert Storm AH-64A was faster (some 20kts / 37km/h), lighter, more maneuverable.

Edited May 28, 2023 by bies

[Tom Kazansky]

Both have similar max weight. Ka-50 has ~10% more power and retractable gear which could be an advantage at high speeds.

edit: I also wonder if the Kamov's coaxial rotors are better for top speeds. There is no loss of energy like the Apache needs with its anti torque tail rotor.

Edited May 28, 2023 by Tom Kazansky

[Hobel]

 

According to the statement of bradmick

Zitat

120 to 130 knots for a loaded aircraft with an FCR, 2 hellfire launchers and 2 rocket pods is accurate.

 

rel:

 

[bradmick]

[Hiob]

I was just about to say - just from the looks of it the KA looks more aerodynamic. Also a tail rotor eats like a couple percent of propulsion power, doesn't it?

[some1]

1 hour ago, v2tec said:

Most of the time I can fly 300 km/h w/o problems (~161 kts) with the ka-50 but the highest speed with the apache was ~124 kts (~229 km/h).

First of all, that 300 km/h you get in DCS is probably with the engines in takeoff range. You wouldn't normally fly like that for a longer time, though I think there's no penalty to do so in DCS. Also take note that the Kamov HUD and ABRIS show GS, which will be higher than IAS shown on AH-64 instruments, unless you're testing on the deck.

Coaxial rotor system is said to be more efficient than conventional. The tail rotor robs you of 10-20% of engine power. On the other hand, the tall main rotor mast of the coax system causes more drag. But the shorter tail that doesn't need to carry tail rotor, with smaller stabilizers that don't need to counter asymmetric torque, all reduce drag. So it's a balancing act.

Overall, Ka-50 probably has less drag. It has narrower fuselage, shorter tail, retractable gear and no dangling gun turret underneath. 

Ka-50 is heavier than AH-64 in typical configurations, but has more powerful engines to offset that a bit. Also I'm not sure how much of the nominal engine power is actually available to the pilot in both machines. IIRC AH-64D is normally limited by its gearbox, not the engines. The transmission won't take the full power of both engines at the same time, that extra power is reserved for engine-out situations.

To sum up, the difference in top speeds between AH-64 and Ka-50 looks plausible. Now you may ask why UH-1 after the latest patch can do 150 kts, or why a fully loaded Mi-8 with external pylons is even faster in DCS, but I don't have answers to these questions.

Edited May 28, 2023 by some1

[FalcoGer]

I read that gearboxes and tail rotor takes up to 20% of power away from lift and forward motion. Not sure where I read that number though. Getting 20% more useful power and less drag certainly would seem like it could make such a difference. In the end though it doesn't really matter if you get there in 30 minutes or 35. Stepping on the gas all the time isn't good for the environment and isn't worth the stress. Take it easy. Maybe take the bike or the bus instead of your personal helicopter.

[petsild]

Otherwise, why is the Apache slow without ammo/fcr with minimal fuel?

[Rhinozherous]

37 minutes ago, petsild said:

Otherwise, why is the Apache slow without ammo/fcr with minimal fuel?

Read posts above, it is not only weight what makes the helo slower. 

[petsild]

There must be a significantly larger speed difference without FSR and full armament, just read the notes of real pilots!

[Amarok_73]

There's another important factor - retreating blade stall. The faster the rotor spins, the higher speed he can get without getting into RBS. Of course olny to some extent, as too high speed of rotor advancing blade will cause it to get to transonic speeds, where the blade will start to deform.

According to the ChatGPT (sorry, couldn't get more reliable sources), the maximal RPM for copters are:
AH-64  - 265
Mi-8/Mi17 - 260-300
Ka-50 - 350.
So it seems, that Kamov should be able to go way faster before getting into RBS, especially, taking in account, he's coaxial, meaning that avearaged forces at this state are equalized, so he's still relatively stable.
 

Edited June 6, 2023 by Amarok_73

[admiki]

3 hours ago, Amarok_73 said:

There's another important factor - retreating blade stall. The faster the rotor spins, the higher speed he can get without getting into RBS. Of course olny to some extent, as too high speed of rotor advancing blade will cause it to get to transonic speeds, where the blade will start to deform.

According to the ChatGPT (sorry, couldn't get more reliable sources), the maximal RPM for copters are:
AH-64  - 265
Mi-8/Mi17 - 260-300
Ka-50 - 350.
So it seems, that Kamov should be able to go way faster before getting into RBS, especially, taking in account, he's coaxial, meaning that avearaged forces at this state are equalized, so he's still relatively stable.
 

 

Ka-50 does not suffer from RBS, but it does get to the point where rotor blades intermesh.

[Amarok_73]

1 hour ago, admiki said:

rotor blades intermesh

...at which point the pilot begins to appreciate the creativity of the designers, who foresaw the need for the ejection seat.

[AlphaOneSix]

5 hours ago, Amarok_73 said:

Mi-8/Mi17 - 260-300

Try 192. No idea where you got 260-300?

[Amarok_73]

5 minutes ago, AlphaOneSix said:

No idea where you got

Like I said, from ChatGPT, did not asked about his source. But i know what You refer to with 192 and can't argue as no any more reliable sources could find.

[AlphaOneSix]

2 hours ago, Amarok_73 said:

Like I said, from ChatGPT, did not asked about his source. But i know what You refer to with 192 and can't argue as no any more reliable sources could find.

Well thankfully, on this subject at least, I am the source.

[Hiob]

6 hours ago, AlphaOneSix said:

Try 192. No idea where you got 260-300?

I think he was talking kilometers per hour. And he‘s right as far as DCS goes. The Hip will reach 260 kph easily. (In game! In reality - no clue)

[Raptor9]

12 hours ago, Amarok_73 said:

According to the ChatGPT (sorry, couldn't get more reliable sources)

ChatGPT may be able to pull "information" from the internet, but it is far from reliable. ChatGPT has no way of knowing what is fact or fiction, it just filters and parrots what it finds on the internet.

As an example, websites like Wikipedia, globalsecurity.org, fas.org, and deagel.com are all "circular reporters." Meaning they post the same crowd-sourced answers that are aggregated from various places; and then when each of these sites have the same "facts", it appears to be corroborated by multiple sources when it really is just a bunch of websites repeating the same thing that the other is saying.

An AI program looks at this and sees corroborated sources as evidence and then outputs it as fact, when in reality it is nothing more than a really fast internet search engine that aggregates and filters data. But like any other computer program, if the data that is input is wrong, so is the output.

I bring this up because there have been several occasions recently where users have quoted ChatGPT as evidence. But caution should be used before any information on the internet is treated as fact, regardless of whether it comes from a human or an AI program.

[AlphaOneSix]

1 hour ago, Hiob said:

I think he was talking kilometers per hour. And he‘s right as far as DCS goes. The Hip will reach 260 kph easily. (In game! In reality - no clue)

He was specifically talking about rotor RPM. Although whatever he was asking may not have understood that.

Edited June 6, 2023 by AlphaOneSix

[Amarok_73]

1 hour ago, Raptor9 said:

ChatGPT may be able to pull "information" from the internet, but it is far from reliable.

I know, that's why I apologized for this source.

I've asked GPT specificaly for RPM, but having in mind his famous confabulation tendency, he could "assume" that I wanted to ask about the maximal speeds.

Edited June 6, 2023 by Amarok_73

[Raptor9]

1 minute ago, Amarok_73 said:

I know, that's why I apologized for this source.

 Fair enough.

[Hiob]

1 hour ago, AlphaOneSix said:

He was specifically talking about rotor RPM. Although whatever he was asking may not have understood that.

 

Oh sorry - misunderstood this one.... I though we were talking airspeed. My bad.

[Dragon1-1]

1 hour ago, Raptor9 said:

An AI program looks at this and sees corroborated sources as evidence and then outputs it as fact, when in reality it is nothing more than a really fast internet search engine that aggregates and filters data. But like any other computer program, if the data that is input is wrong, so is the output.

It's worse than that. It has no context whatsoever, it's just a language model. It answers the question of "what's most likely to follow the words 'Max rotor RPM' and 'Mi-8/Mi-17'?" Answers it gives contain no genuine information. Everything that it says is essentially a guess, if it's correct, it's either by pure luck, or because that particular set of words is unique enough that the right answer is the most likely one to follow it. It's inherent in the very nature of the model, even the most advanced ones do not understand anything about what the words mean.

A perfect replacement for politicians, middle managers (then again, so is a potted plant), lawyers, gossip "journalists" and more than a few higher officers out there (you know the type, I'm sure).  For anyone who has use a brain once in a while, it's basically a souped-up autocorrect. The real danger it poses is that it encourages the "garbage in, gospel out" phenomenon when people don't understand it's inherent limitations.

[Amarok_73]

1 hour ago, Dragon1-1 said:

(...)A perfect replacement for politicians, middle managers (then again, so is a potted plant), lawyers, gossip "journalists" and more than a few higher officers out there (you know the type, I'm sure).  For anyone who has use a brain once in a while, it's basically a souped-up autocorrect. The real danger it poses is that it encourages the "garbage in, gospel out" phenomenon when people don't understand it's inherent limitations.

Very accurate summary, I'd say...