Aero Commander 680 Super - Next

[Milton Shupe]

The AC680S is the next and last in line for the Aero Commander series of conversions to FSX Native.

This one will be a different challenge as there are actually 3 models and two or three different panels / VCs involved.

Not sure how I will proceed, but its more at 3 different projects. But some time should be saved by sharing the exterior model, I hope.

Seeing the liveries posted, the 680S Pegasus is also to be included but the alphas will need an artists FSX touch before it can be released.

This project will likely require 2 weeks.

 

[PhantomTweak]

Wow!
Can't wait. I'm wondering when I'll have time to fly all these beauties. Well, I will figger it out somehow.
I'm sure glad I have a very understanding (and beautiful!) wife or I'd be in trouble

Pat☺

 

[Henry]

I cannot wait!

BUT I HAVE TOILOVE THOSE LIVERIESH

 

[Willy]

Milton, will the texture mapping remain the same? If so, let me see what I can do with the Pegasus one.

 

[Milton Shupe]

Milton, will the texture mapping remain the same? If so, let me see what I can do with the Pegasus one.

Yes, compatible with all the original textures on the exterior.

But you must wait for the model with the FSX materials settings.

Thanks

 

[Milton Shupe]

BUT I HAVE TOILOVE THOSE LIVERIESH

LOL Thanks H

 

[Willy]

Yes, compatible with all the original textures on the exterior.

But you must wait for the model with the FSX materials settings.

Thanks

I just ported over the FS9 vc version Pegasus for a quick look. The metal is a bit "washed out", but that's nothing that's not fixable. I'm going to see what I can do about getting it ready to work on by getting it into the paint kit for conversion.

 

[blanston12]

Excellent! I really have been loving these aero commanders, thanks so much for updating them.

 

[Craig Taylor]

Yay! Thanks Milt and Willy!

 

[Milton Shupe]

I just ported over the FS9 vc version Pegasus for a quick look. The metal is a bit "washed out", but that's nothing that's not fixable. I'm going to see what I can do about getting it ready to work on by getting it into the paint kit for conversion.

Willy, Nigel started redoing the Pegasus back in 2012 but it was not completed. I am looking for that work.

Excellent! I really have been loving these aero commanders, thanks so much for updating them.

I am happy to do it and really appreciate that people still can enjoy these old standards.

Yay! Thanks Milt and Willy!

You bet!

I am still tweaking things based on beta test feedback but still hope to get the 500 out tonight as most of these things are very minor adjustments.

 

[Willy]

Willy, Nigel started redoing the Pegasus back in 2012 but it was not completed. I am looking for that work.

Ok. Hopefully he still has it.

Speaking of old Aero Commander paints, there was one years ago of one that two young men flew around the world. Any idea of where that paint could still be found? Last time I had it, I had a hard time finding it.

Edit: Found it. It's included in the FSX native package.

 

[BendyFlyer]

This was my first encounter with AC680 way back in 1978. It was very impressive then and still is today. They used to call it the mini-airliner. With good reason you needed an airline budget to look after the geared supercharged engines which were maintenance hogs and prone to being overboosted by hamfisted pilots with a lot of damage as a result. They performed allright but expensive to maintain which is why there are so few of them about today.

 

[expat]

Silly question time, but was also thinking about those Lycomings Were they geared up or down? My guess is down, but not sure why props with so little friction vs road wheels or ship screws would need or benefit from the extra torque/pulling power of a "low gear" whereas higher prop rpm (geared "up") would deliver greater performance? Or, maybe it's the same principle of reducing prop pitch - and rpm - in cruise, and squeezing out that extra IAS?

 

[Milton Shupe]

Silly question time, but was also thinking about those Lycomings Were they geared up or down? My guess is down, but not sure why props with so little friction vs road wheels or ship screws would need or benefit from the extra torque/pulling power of a "low gear" whereas higher prop rpm (geared "up") would deliver greater performance? Or, maybe it's the same principle of reducing prop pitch - and rpm - in cruise, and squeezing out that extra IAS?

BendyFlyer is probably in the best position to answer your question.

The 680 engine Geared and supercharged made its best power at TKOF of course at 3400 rpms. Props are restricted typically to <2100 rpms.

Generally, you do not want the prop tips to go supersonic (noise and efficiency) and blade length plays into tip speeds.

So you will often see geared props on larger prop length aircraft. and they will use more blades at a shorter length to reduce prop tip speeds while achieving the desired thrust.

The 680 is geared to restrict tip speeds to .792 mach and with 3 shorter blades, there is plenty of thrust.

 

[Milton Shupe]

I mentioned that the AC680S has 3 different models and two different panels.

I have one model and panel converted.

The later model panel and the cargo version for the FEDEX livery are still pending.

In these screen shots, the PT-BUF and IKE versions are converted, and the Pegasus is temporarily using the converted model so Willy can work on the livery.

The cargo version is using the newer panel/vc version and is shown using the FS9 portover model.

 

[BendyFlyer]

BendyFlyer is probably in the best position to answer your question.

The 680 engine Geared and supercharged made its best power at TKOF of course at 3400 rpms. Props are restricted typically to <2100 rpms.

Generally, you do not want the prop tips to go supersonic (noise and efficiency) and blade length plays into tip speeds.

So you will often see geared props on larger prop length aircraft. and they will use more blades at a shorter length to reduce prop tip speeds while achieving the desired thrust.

The 680 is geared to restrict tip speeds to .792 mach and with 3 shorter blades, there is plenty of thrust.

The engines were generally and are today geared down to do a number of things, first is the rotational force of the weight of a propeller rotating about a shaft and hub, which is why as engines became more powerful the blade numbers increased, there was a weight increase but the blade length was critical because the speed of the air over the blade varied from the hub join to the tip as did the blade section or angle of attack, so as Milton correctly points out beyond a certain speed the tips can go supersonic if the rotational speed is not reduced. Increasing the number of blades increased the weight but meant you can reduce the blade length, and it also reduced the noise generated by the props (two blade props are inherently noisier than 3 blades etc.).

The engine gearing was to keep the egnine speeds down and for props this is ideally about 3400 RPM max , on a lot of high powered pistons used in say a car you could have an engine that would do say 6000 RPM at max power but you had to keep the prop speed back to about 3000 RPM, it is one of the reasons V8 and car engine conversions were never really successful because while you would get good power you had to gear the engine down via a gearbox which sort of defeated the whole exercise. Supercharging and turbocharging was a neat way to develop power out of an engine with decreasing atmospheric pressure and to get the most you could out of an engine without having to build a very large engine. All aircraft piston engines are by design long stroke engines with low compression ratios which keeps them operating at low RPMs without the need for gearing. Needed more power? add more cylinders. Boat propellors are a different problem again because they are operating a dense liquid water, so you want the propeller rpm to stay low and the blade or prop section to develop maximum push (note how broad and large they are) and they were designed to go on low speed engines. The other problem with a boat propeller is cavitation, where if the prop rpm gets to high it begins to trap oxygen bubbles about the blades caused by the water flow and turbulence and that leads to loss of thrust to the point the prop could be at very high rpm but generating no thrust.

Another consideration is engine over-speed so if the aircraft is in a dive the prop RPM can increase very rapidly and over-speed the engine. Effectively a propeller is just another airfoil designed to produce lift but rotating the blade the lift is translated into thrust via a helical slipstream of air pushing the air back. A good example of prop noise and supersonic is the RR Dart Engine such as used on the Fokker Friendship, the distinctive high pitched whine of this engine-aeroplane was not the engine but props generating a noise and they were basically very close to being supersonic all the time.

Propeller design is a very technical field indeed which is why even today the propellers are made by specialist companies.

 

[Willy]

by design long stroke engines with low compression ratios which keeps them operating at low RPMs without the need for gearing. Needed more power? add more cylinders

Ala 1930's automobiles. Which is why there were V-12 & V-16 engines in luxury automobiles back then. They needed more power to pull those big heavy cars and the engine technology (and octane levels) just wasn't up to it back then. So, they added more cylinders.

 

[Milton Shupe]

The 680S package is ready except for some panel textures that need the attention of a painter.

I need some shading and some text added to the left and right side panel bmps.

I have a package ready to share if someone has the time.

Thanks for your help in advance.

EDIT: The request has been answered. Thank you

 

[gribouil]

Hi Milton,
manny thanks for your beautiful native Commanders!
I have a question though:
Do you intend to release a native version of your Shrike Commander 500S?
I especially think about your "Bob Hoover" texture...
Cheers,

Stéph.

 

[Milton Shupe]

Steph,

The 500S Shrike was done by a team member I mentored in gmax back in 2003-4 and I do not have the gmax source to it.
I have looked at it in MCX to export a 3dsmax file and convert to gmax but the conversion mesh looks really bad.
It would be easier to rebuild it with much better results in my opinion than to convert it.

So, I am not likely to convert that one.