CH-47 vs CH-53

[Tony Williams]

I thought I'd ask this question here given the level of aeronautical expertise on this site.

(That's the flattery over with, now to the question ;D )

In most western countries, the go-to choice when heavy vertical lift is wanted is the CH-47 - nothing else seems to be considered. Yet on a paper comparison basis, when comparing roughly similar generations, the CH-53 seems to show up very well, being more powerful and having a greater payload. Also, I vaguely recall seeing stats which suggested that the CH-53 was less expensive to buy and run. Despite this, AFAIK only the USMC and the German Army (now Air Force) make significant use of it (and they seem to like it).

So why is the CH-53 ignored? Do I have my figures wrong, or is there some other factor working in the CH-47's favour (greater load-carrying tolerance with two rotors, or something?). What are the pros and cons of the two types?

 

[fightingirish]

IMHO the basic CH-47 Chinook is in the medium heavy lift class for a helicopter, and the basic CH-53 Stallion is in heavy lift class.
The Chinook may not carry the loads and have the speed like a CH-53, but it has better peformance at higher altitudes.
BTW, Israel has a large CH-53 fleet, too.
Anyway, I am looking forward to the Sikorsky CH-53K Super Stallion for the USMC. But I only can see Israel and Japan as export customers for the CH-53K.
Germany will wait for the Heavy Transport Helicopter (HTH) in 2020's.

 

[CostasTT]

I thought I'd ask this question here given the level of aeronautical expertise on this site.

(That's the flattery over with, now to the question ;D )

In most western countries, the go-to choice when heavy vertical lift is wanted is the CH-47 - nothing else seems to be considered. Yet on a paper comparison basis, when comparing roughly similar generations, the CH-53 seems to show up very well, being more powerful and having a greater payload. Also, I vaguely recall seeing stats which suggested that the CH-53 was less expensive to buy and run. Despite this, AFAIK only the USMC and the German Army (now Air Force) make significant use of it (and they seem to like it).

So why is the CH-53 ignored? Do I have my figures wrong, or is there some other factor working in the CH-47's favour (greater load-carrying tolerance with two rotors, or something?). What are the pros and cons of the two types?

Going just from memory here, the CH-47 is favored since all power can go to both rotors for lift, whereas the tail rotor of the 53 draws some power that would have otherwise been used to provide lift. In addition, the 47 is less sensitive to side winds and generally easier to load to/from trucks, since it doesn't have a tail boom.

 

[Sea Skimmer]

The tandem rotor is a very stable helicopter configuration which counts for a lot operationally, though the drawback is less agility to deal with enemy attacks. The twin engine CH-53 models main advantage is size, with folding tail boom it fit on amphibious warfare ships better for the performance. That's why the Sea Stallion existed, and why the smaller Sea Knight was the same tandem configuration as Chinook, and why the V-22 is so complicated in how it folds up.


If you don't have the space limitation you don't care, you buy Chinook because it can accomplish the missions you need while being extensively supported world wide. Only people who need the utter edge of vertical lift at low altitude considered Sea Stallion as a land helicopter, which is functionally just been Germany and Israel. The former for that airborne anti tank brigade concept, the later seemingly because of the ranges involved in a small country favoring it. Most people would rather have more aircraft.

You don't for example see many artillery pieces that a Chinook couldn't lift but a Sea Stallion could meanwhile. I've never seen a thing to suggest Sea Stallion has ever been cheaper to buy or fly, and that really doesn't even start to make sense. Presently a Chinook is under half the price projected for CH-53K, though the later is by any standard a completely new aircraft. CH-53E was certainly not a remotely cheap thing either. Extra engines cost money!

 

[Tony Williams]

Thank you for your responses, gentlemen, some light is shed.

I went on a hunt for helicopter running costs and the best I could find was this: http://www.washingtoninstitute.net/ftpFiles/StudentFinalProjectReports/TFM24/WardHiesterman.pdf , which has a table at the end indicating that in 2009 the cost per flight hour of the BV-234 (commercial CH-47) was $6,576 and that of the CH-53D (mislabelled OH-53D) was $6,417, so not much in it. The figures I recall were buried in a more general official document so not very amenable to googling.

 

[Abraham Gubler]

Only people who need the utter edge of vertical lift at low altitude considered Sea Stallion as a land helicopter, which is functionally just been Germany and Israel. The former for that airborne anti tank brigade concept, the later seemingly because of the ranges involved in a small country favoring it. Most people would rather have more aircraft.

I'm not sure about the Germans but the Israelis brought the CH-53D before the CH-47C was available. Earlier models of the Chinook had some significant problems and no one except the US Army wanted to touch them. When the CH-47C became available the market scape changed significantly.

 

[yasotay]

Only people who need the utter edge of vertical lift at low altitude considered Sea Stallion as a land helicopter, which is functionally just been Germany and Israel. The former for that airborne anti tank brigade concept, the later seemingly because of the ranges involved in a small country favoring it. Most people would rather have more aircraft.

I'm not sure about the Germans but the Israelis brought the CH-53D before the CH-47C was available. Earlier models of the Chinook had some significant problems and no one except the US Army wanted to touch them. When the CH-47C became available the market scape changed significantly.

Indeed it was not until the CH-47D that many of the issues with the Chinook were overcome. Early on no one wanted the "Boeing Body Bag" because their combining gearbox (the one that kept the intermeshing rotors from meshing) was not fully reliable with the expected results. That was mostly fixed on the CH-47C. The early Chinooks were very leaky with hydraulic fluid and gearbox fluids all over the place, especially the rear ramp. CH-47 crew chiefs were easy to spot because they were the ones wearing the flammable flightsuits (unidated with hydraulic fluid). The old joke was not to get on a Chinook that was not dripping because that meant the hydraulic fluid was all gone.
Both aircraft fill a similar mission but have very different requirements. As mentioned above, like all naval aircraft the CH-53 series had to fold up. Between that and the anti-corrosion requirements it is a very heavy aircraft with more maintenance required. The Navy and the Army look at maintenace very differently. The H-53 has a lot of kit on it that most countries in the market for medium/heavy lift are not interested in buying. That is why there are more CH-47 in the world than CH-53.
The point about taking power away from lift is also relevant when it comes to utility. This is why CH-47 (and Kamov products) are able to operate at higher weights at heigher altitudes because they do not have to expend power to overcome torque.

 

[Tony Williams]

Both aircraft fill a similar mission but have very different requirements. As mentioned above, like all naval aircraft the CH-53 series had to fold up. Between that and the anti-corrosion requirements it is a very heavy aircraft with more maintenance required. The Navy and the Army look at maintenace very differently. The H-53 has a lot of kit on it that most countries in the market for medium/heavy lift are not interested in buying. That is why there are more CH-47 in the world than CH-53.
The point about taking power away from lift is also relevant when it comes to utility. This is why CH-47 (and Kamov products) are able to operate at higher weights at heigher altitudes because they do not have to expend power to overcome torque.

Do similar factors apply to the Mil Mi-8/17 family as compared with the Kamov Ka-27+? Both seem to be around the same size but the Mils have been far more successful in international sales.

 

[CostasTT]

They may appear to be similarly sized, but the cabin of the Kamovs is much smaller (capacity 16 troops in the Ka-29TB vs 30 in the Mi-17). The lower cabin roof, the relatively small side doors and total lack of rear doors/ramp limits their overall utility compared to the Mils. There is also their history to consider: Traditionally, Kamov has been focusing on naval applications, leaving Mil to cover the land based field. The stability of the coaxial rotor configuration favored by Kamov means that there is a niche for their product for more specialized roles, but as a general utility helicopter the Mi-17 wins hands down.

 

[yasotay]

I suspect that the simplicity of the Mil over the Kamov is another reason for the favoring of the ubiquitous Mi-8/17 over the Ka-27. Although the Ka-27 has found a niche in the logging industry in the west. I will leave it to the aero-engineers out there, however I suspect that a coaxial (Kamov) designed to the same specs as the Mi-8/17 would be about the same size but might be heavier due to the transmission and rotor system. Newer technology might reduce that though.
Ka-92 versus Mi-8/17? Size? Installed power?
Still same situation applies, the naval rotorcraft with all of its preculiar needs does not appear as marketable overall.

 

[sferrin]

Germany will wait for the Heavy Transport Helicopter (HTH) in 2020's.

I wonder if they'd bother to spend the money to develop one when the CH-53K would be available off the shelf.

 

[Avimimus]

Doesn't the Ka-29TB have improved armour and a host of naval/safety features? It also has the built in turret and can be quickly re-equipped with a 30mm cannon. I always saw it as more of a commando transport and support helicopter gunship (similar to the Mi-24 but larger/slower and navalised). The Mi-24 also failed to gain a substantial civilian market if I recall...

 

[Tony Williams]

The Mi-24 also failed to gain a substantial civilian market if I recall...

I thought that the export Mi-35 was one of the most widely used combat helos? There seem to be some around in just about every country which uses Russian equipment.

 

[Sea Skimmer]

The old joke was not to get on a Chinook that was not dripping because that meant the hydraulic fluid was all gone.

Funny, people pass around the same joke about the CH-53E. Makes you wonder.

I thought that the export Mi-35 was one of the most widely used combat helos? There seem to be some around in just about every country which uses Russian equipment.

Its very popular for combat use yes, but for civilian use its almost unheard of even though the Soviets did make a small range of civilian models for domestic use. I think though most were conversions. Kinda not surprising considering that it just can't be very economical in a utility role, though it does have the ability to take a cargo hook and lift non trivial loads.

 

[bobbymike]

http://www.americanmachinist.com/machining-cutting/boeing-modernize-increase-lift-us-army-helicopters