Community A-4E

Great!

Was that PPL or CPL?

Instrument Rating is not license specific in the US, but it is category/class specific. Mine is ASEL. I don't have my CPL, but that's my next goal.

--gos

Excellent!

Lol....methinks you are following the Zach Brown Band recipe for vaction...

"I got my toes in the water, ass in the sand, not a worry in the world, cold beer in my hand...."

Getting close to monthly update time ;)

Yeah, I'm starting to get that clammy skin feeling! I'm getting all nervous and twitchy and I can't seem to settle down. I......I need....a sssScooter fix!! :cry: :helpsmilie:

a-4e development is on hold, we're all too busy crashing our harriers

/s

a-4e development is on hold, we're all too busy crashing our harriers

:(

a-4e development is on hold, we're all too busy crashing our harriers

 

 

 

/s

I approve.

a-4e development is on hold, we're all too busy crashing our harriers

 

 

 

/s

ROFL!

:joystick:

Community A-4E: November 2017 Update

Community A-4E: November 2017 Update

So, not much to report this month. A lot of small 3D/2D changes are being made, but since we have multiple artists working together and sharing the work, the pipeline isn't the most efficient. We just aren't quite ready to share any of the new images just yet.

Code wise, building upon a debug interface first created last year, we added dynamic logging of certain flight parameters. While in the past we could tune some of our systems live while flying, having a data feed we can import to excel allows for offline analysis of dynamic conditions in a way that is hard to "see" and address live.

This infrastructure is flight model independent, but for now we're using it to tune the SFM, and I thought I would post just one simple example.

The following plot was our first use of this logging, prior to tuning any flight coefficients. We have are 3 datasets which plot lifting force in terms of load factor * gross weight in 1000s of pounds on the Y axis, and mach number along the X axis. These were (are?) the units for NATOPS maneuverability plots from that era.

• Orange squares are the design maximum lift.
  
• Grey triangles represent the projected buffet onset.
  
• Blue diamonds are measured datapoints from our SFM.
  

As you can see, maneuverability between mach 0.3 and mach 0.5 is pretty close to accurate. Above mach 0.5, our model essentially splits the difference between buffer onset and absolute lift capability. Additionally, it's obvious we haven't implemented a lift-force limit yet, given the higher lifting force possible beyond the airframe's design limit at higher speeds.

It isn't obvious (yet) whether this is a function of the test environment used for the wind tunnel data we referenced, or whether we interpreted some of it incorrectly, or whether the NATOPS estimates have errors in this regime, but we'll sort it out.

Oh, and since we know a lot of people wish we would release this mod sooner rather than later, the team thought we could better explain our progress graphically:

As you can see, lack of progress isn't our fault. :lol:

Thanks again for everyone's support!

--gos

I look forward to crashing the A-4 upon completion. :)

Thanks for update guys!

Sure !

Code wise, building upon a debug interface first created last year, we added dynamic logging of certain flight parameters. While in the past we could tune some of our systems live while flying, having a data feed we can import to excel allows for offline analysis of dynamic conditions in a way that is hard to "see" and address live.

As you know, I have been developing an A4 Skyhawk https://forums.eagle.ru/showthread.php?t=123434 prior to yours. my mod is a bit older and currently only in use by airshow teams, but yours is further along. I have firsthand working knowledge with this aircraft. I was a jet engine mechanic in the Navy in the middle to late seventies. I Had the unique opportunity of having been stationed at Miramar . "Top Gun" during its heyday when these aircraft were in use daily. as a 3-D modeler with close to 10 years experience, I would even join forces with your team. you guys have done an amazing job. I have a number of different aircraft that I'm currently working on , which could benefit from your ability to track the flight model in Excel. Since this is a "community mod" would you be willing to share some of your development technology specifically your ability to data log, with the community?

Keep it up!!! I personally like the update pics but Don't need them. Happy to know you are working to bring us a really nice Scooter. Y'all take all of the time y'all need, it'll be better for everyone in the end!!

... as a 3-D modeler with close to 10 years experience, I would even join forces with your team. you guys have done an amazing job. I have a number of different aircraft that I'm currently working on , which could benefit from your ability to track the flight model in Excel. Since this is a "community mod" would you be willing to share some of your development technology specifically your ability to data log, with the community?

We appreciate the offer for assistance, however, at this point in time, we prefer to stick with the team of contributors that we assembled almost exactly two years ago. To us, the process of working together and learning what it takes to make a mod for DCS is more important than the final mod itself.

As to releasing our source lua code, we plan to release most of it. We are not planning to release any of our code ahead of the mod being available to everyone.

--gos

Based on your interpretation of the charts; at 10,000 ft the A-4 can hit a load factor of 87,500 lbs at mach .56. This would require a Cl of 1.05. Roughly 25% above where NASA places it. If you also look at the sea level performance charts for the A-4. The slowest velocity you can hit the structural limit at is mach .53. With a wing area of 260 feet, that put’s the Cl at .8. This matches the Cl max from NASA. This this leads me to believe, the area in the “maximum lift” section, are not part of the actual flight envelope, but possibly the theoretical limits of the 2-d airfoil.

There this other good evidence to this effect too. For example, the corner velocity for the 10,000 ft chart on the “buffet onset” gives a load of 60,000 lbs, at Mach .51, at 10,000ft. With a wing area of 260^2 ft, the Cl needed to hit the load factor, for a wing of this size comes out to .8. Again it’s same NASA found for Cl Max with a full scale wind test of an A-4.

Based on your charts, I would say your Cl max is to high you should tune to target the buffet onset. If you try and adjust the Cl to hit “maximum lift” limit up at the slower speeds, you’ll need more Cl to hit those structural limits, which is counter-intuitive.

I also would like to try and head off any discussion about slats. At the speed these instantaneous turns are being flown, the slats would not be deployed. The slats on the A-4 were like those on the Bf-109, on rollers and held up by the on coming airflow. At corner velocity, mach .5 they will be up. It really doesn’t take much speed to hold them up. They come most of time before the catapult shot is over.

Based on your interpretation of the charts; at 10,000 ft the A-4 can hit a load factor of 87,500 lbs at mach .56. This would require a Cl of 1.05. Roughly 25% above where NASA places it. If you also look at the sea level performance charts for the A-4. The slowest velocity you can hit the structural limit at is mach .53. With a wing area of 260 feet, that put’s the Cl at .8. This matches the Cl max from NASA. This this leads me to believe that those area’s in “maximum lift” are not part of the actual flight envelope, but possible the theoretical limits of the 2-d airfoil.

 

 

This other good evidence to this effect too. For example, the corner velocity for the 10,000 ft chart on the “buffet onset” gives a load of 60,000 lbs, at Mach .51, at 10,000ft. With a wing area of 260^2 ft, the Cl needed to hit the load factor, for a wing of this size comes out to .8. Again it’s same NASA found for Cl Max with a full scale wind test of an A-4.

 

Based on your charts, I would say your Cl max is to high you should tune to target the buffet onset. If you try and adjust the Cl to hit “maximum lift” limit up at the slower speeds, you’ll need more Cl to hit those structural limits, which is counter-intuitive.

 

I also would like to try and head off any discussion about slats. At the speed these instantaneous turns are being flown, the slats would not be deployed. The slats on the A-4 were like those on the Bf-109, on rollers and held up by the on coming airflow. At corner velocity, mach .5 they will be up. It really doesn’t take much speed to hold them up. They come most of time before the catapult shot is over.

Agreed with most of what you wrote, especially about re-tuning for buffet onset to give a more typical experience.

Slat extension (and changes in Cl) begins below M0.3 at sea level, based on descriptions that the slats were expected to be fully retracted by 200 KIAS. Due to SFM table limitations, we cannot calibrate this effect directly to KIAS, so it will only be accurate at a single altitude. We chose sea level.

We can also add a hard cutoff for Cl (Clmax), a bit above the buffet onset at a mix of airspeeds, but I've done no testing in that area.

These graphs were (are) our first attempt at actual testing and calibration of our FM.

thanks!

--gos

Based on your interpretation of the charts; at 10,000 ft the A-4 can hit a load factor of 87,500 lbs at mach .56.

One comment. Our FM tuning so far was merely mapping in the experimental lift/drag polar data from a scale wind tunnel test. No tuning to the performance charts has been attempted yet, this was our first comparison.

--gos

One comment. Our FM tuning so far was merely mapping in the experimental lift/drag polar data from a scale wind tunnel test. No tuning to the performance charts has been attempted yet, this was our first comparison.

 

--gos

Cool, thanks for all your work on this. I really dig the project. The A-4 is a really interesting aircraft. That NASA doc I linked is a pretty good read too. Full scale wind tunnel tests, to evaluate various battle damage on the polars. They actually had the Air force shoot two different sets of wings with 25mm and 30mm guns, to asses the effects on the craft. There is even a polar for the approach config.

The depth and intelligence of this conversation is mind-blowing. I'm totally nerding out to it right now. Keep it up guys and figure this girl out!

Did they seriously put 3 Zuni pods strapped together on a single hardpoint on something the size of the Scooter? I was looking for any evidence of multiple Zuni pods on a single hardpoint 'cause they're the best rocket for the Harrier (until APKWS is implemented) when I came across this and figured you folks would enjoy the chuckle.

Yup, A-4E/F allows 1 rocket launcher tube on the outboard stations, 2 on each of the inboard stations, and 3 on the centerline. A-4C has the same allowances on the inboard and centerline.

Allowed types are the LAU-3A/A (19-tube 2.75"), LAU-10A (4-tube 5" 'zuni') and LAU-32A/A.

It's quite the capable bomb & rocket truck.

--gos

SHUT UP AND TAKE MY MONEY!!1!

I <3 bomb trucks! Especially those called “Scooters”!