Iran Military Forum

So you're saying that the Shahed 285 is lighter than the Bell 206, therefore it must have a lower range and payload? I think you'll find it is the other way around.

They use the same engine, if the shahed 285 weighs less than the bell 206, then basic common sense would indicate that the payload and range are higher.

What I state is based on general principles for Iran has not released any technical date on it's own and I doubt it shall given a historical precedence of not doing so. Also, concerning aircraft, the proportionality between different figures isn't as simplistic and nor is it always as reciprocal-- i.e a reduction in size and weight would result in increased payload if other attributes are same. To point one example, a reduction in size reflects a decreased amount of space for fuel storage with it being made to compete with space for other equipment more. Also, fuel adds to the maximum take-off weight. If the aircraft has been made lighter and more condensed without a more improved powerplant, it would indeed have a bearing on it's operational range. If not, then most probably it would sacrifice weight by reducing what other payload it carries. Point being, changing one attribute affects others. The problematic issue for me in developing a real consensus is the lack of technical information.

The engine is still the same therefore the decrease in weight will increase its payload and range. That is a basic rule of thumb.

Shirazi, point is, the decrease in weight has to be brought about by sacrificing atleast one weight characteristic-- fuel capacity, payload or more noticeably here, the reduction to a single operator. If we are to assume that the range has been significantly enhanced even with reduced weight and significant reduction in size, it could be said what would have been the ability to hold more equipment (or munitions) has been sacrificed for that purpose. 

Now remember those specs I posted are not the attack helicopter (Shahed 285) but the Shahed 278 for which the Shahed 285 is 'evolved' from. I posted those specs so we can at least have a starting point for which we can gauge the possible specifications of the Shahed 285. The specifications I posted came from the ACIG's report of the Iran Airshow 2005 in which they claimed the specifics were given publically.

I apologize that I added some confusion without being more specific.

Now clearly from images we have of the Shahed 285 we can conclude it is likely lighter since it now has a smaller cockpit and doesnt appear to have a passenger cabin anymore. How much lighter I honestly couldnt tell ya though.

But I did find any interesting image to help us make an educated guess about the difference in size. The image shows a comparision of the OH-58 Kiowa Warrior (essentially an armed JetRanger), the Shahed 285 and the CH-14 (an Argentine design using a similar engine but with a much different seating arrangement).

Now from this, its clear the Shahed 285 is slimmer and possibly a bit shorter than the original JetRanger. This combined with likely being built with composites (Carbon fiber) means the empty weight of the Shahed 285 would likely be at least 100-200kg lighter. Therefore, being lighter and slimmer but with the same engine as the original design means the Shahed 285 is likely faster and more agile than the Jetranger but how its range and payload would be affected I am not certain. The slimming of the airframe would in theory reduce the amount of fuel but the elimination of the passenger cabin could more than make up that difference.

The real trick is the Shahed 285 is rather unique by most standards. Being manned by a single pilot is quite rare in its own..It being build for observation and light attacks adds to this further. Long story short, its makes it pretty damn hard to guess its capabilities.

You guys forgot to add the weight from the weapons and on the Kosar variant

Remember that a full load of fuel would weigh 287 kg and the pilot and gear would weigh roughly 80 kg. Rocket pods with 14 Hydra 70 rockets add another 91 kg while the 12.7 mm machinegun would probably also be around 80-90 kg though that's really just a stab in the dark although i know for sure the gun and ammunition would make up 50-60 kg alone. I have no idea how much the pylons and wing stubs would weigh.

I'm not positive because i haven't seen a technical drawing, but in the 206/278 i'm guessing there would be fuel cells in the floor and maybe behind the passenger compartment. In the 285 the frontal profile is reduced so the floor fuel capacity would be reduced as well, but then again, it could be moved to rear of the cockpit. I guess at this point it's a tossup with regards to fuel capacity. I'd be willing to bet that a 287 liter fuel tank could be made to fit into the Shahed 285 without significant sacrifice.

Looking at the pictures, i'm guessing the gun used is an NSVT or perhaps even PKMT.

Kosars weigh about 100kg each.

Shirazi that is another assumption put forward by you about arguing. Regardless, Shirazi the Bell 206 does have a 'payload' which is reflected in the amount of extra weight it can hold, crew inclusive. Also, you underestimate the weight chracteristics of fuel. Furthermore, given how compact the Bell 206 was to begin with, a reduction in dimensions and weight would have been brought about by the sacrifice of some element.

As to the last part, it may be possible but it isn't a rule of thumb as you purport. Refer again to my earlier post on proportionality of aircraft attributes and how changes aren't always reciprocal as you are willing to assert. 

The payload has nothing to do with the weight. You are saying that the shahed 285 has sacraficed the possible weightload of the bell 206 to become lighter, this just does not make sense, i don't see how anyone could get to this conclusion.

The payload has nothing to do with the weight.

Shirazi, payload itself is a type of weight with the added dimension of space.

Shirazi,

Payload has everything to do with weight. There are always three elements of weight when discussing any aircraft including helicopters: Empty weight, Fuel load, and Payload

1. Empty Weight- The actual weight of the airframe and internal systems without any fuel or passengers
2. Fuel Load- Maximum amount of fuel that can be carried internally.
3. Payload- This is any extra cargo or weight that can be carried while still allowing the helicopter to still achieve flight.

All these elements added together are what makes up an aircrafts Maximum Take-Off Weight.

Now, the Fuel load and Payload can vary depending on mission but their combined weight cannot exceed the MTOW when added to empty weight of the helicopter.

Now assuming the Shahed-285 uses the same engine as the Bell 206 and Shahed 278 (Rolls Royce 250-C20), and the Shahed 285 does have a lighter airframe (which is highly likely), determining its possible payload or fuel load is problematic.

For example, the likely reason the Shahed 278 was some 95kg lighter than the original Bell 206 is because its airframe probably uses some composites in its construction resulting in a 12% decrease in empty weight but maintaining the MTOW.

Now the Shahed 285 likely uses even more composites in its construction considering its appearance which would further lighten the airframe and combine that with the slimming of the airframe we are looking a helicopter that could have a Empty weight of <600kg. This would put the Shahed 285 in the same weight class as the various members of the MD-500 family of helicopters.

The fuel load is also tricky to determine because while the airframe has gotten dimensionally smaller, the areas for fuel have possibly increased because now there is only one pilot and there is no passenger cabin anymore so its even possible the Shahed 285 could carry more fuel than the original Bell 206.

So, I can’t say with any certainty whether the Shahed 285 will have a greater payload or greater MTOW compared to the original Bell 206 but considering what it could be armed with I don’t think it matters that we don’t know for certain. A helicopter of this size and relative class can carry plenty of usable armament (such as rockets, missiles, or gun pods). If my guess at its Empty weight is right, we are talking about a helicopter that would be similar in performance and possible armament to a MD-500MD Defender and possibly better.

Eagle, that is not what Ruhollah is saying. He is saying that the Shahed 285 has reduced its weight by sacraficing the payload of the bell 206, therefore the shahed 285 has reduced its payload by reducing its weight. This does not make sense any way you look at it.

You can't save weight by reducing the possible payload of a helicopters. Whgat he is saying doesn't make sense, so much so that it is even hard to explain what he is trying to say.

Essentially he is saying that the shahed 285s empty weight is lower than the empty weight of the bell 206 because it carries less payload than the bell 206.

Well, the fact that you are having difficulty explaining it is because you haven't quiet understood what I have stated, which also explains what you have put above is also incorrect. If I must, I'll state my self again, much more briefly this time though.

Firstly,

The engine is still the same therefore the decrease in weight will increase its payload and range. That is a basic rule of thumb.

1) No, it's isn't a rule of thumb. The proportionality between different attributes of a helicopter aren't simplistic thumb rules whereby they would be reciprocal as you believe above-- i.e altering one attribute influences others (either incrementing or decreasing them) rather than them staying stationary or unchanged.

Then,

They use the same engine, if the shahed 285 weighs less than the bell 206, then basic common sense would indicate that the payload and range are higher.

2) Not necessarily, a reduction in overall dimensions alongside overall weight doesn't characteristically result in increased payload if other attributes are same. In the absence of figures-- for instance we do not know how much of the reduction in size and overall weight has been matched by the elimination of cockpit space-- a statement as above cannot readily be made, that is what common sense would dictate at least. Also refer again to the first point on the balance of the various elements of a helicopter-- just because the power plant is identical yet all other elements have been altered, it doesn't lead to a conclusion that there would be a reciporal increase in range and holding capacity. Also, when you bring in range, you put in the relation with fuel and we have no way of judging how much the fuel capacity has been altered.

Lastly,

That is hilarious.

3) I am sorry you see it that way but payload has direct correlations with weight, being itself a characteristic of weight and space (area) combined. In a much larger sense, all of these have a bearing on the efficient operation of the helicopter.

As you know I am not a native English speaker. I therefore cannot put it more clearly then above but if there are stills some specifics, I could oblige further. 

One thing that i haven't noticed before is the different hardpoints. While the models that were on display showed two ejector racks for rockets mounted about halfway along the wing , the video of the helicopter flying shows the ejector racks being moved to the far end of the 'wings'. These means that each helicopter potentially has 4 hardpoints instead of two, although i doubt you could mount anything else on there with the Kowsars.

I do not understand why this is not the weapon used. This is in here. 2 pieces. Easy and fast.
Akhgar machinegun
http://64.130.220.65/Multimedia%5Cpics%5C1389%5C7%5CPhoto%5C110.JPG

Here's a great find that was posted by a member of the Iran Defense Forum (username UNKNOWN)..Enjoy!