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Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Aug 2014, 04:49
by sprstdlyscottsmn
mixelflick wrote:Amazing analysis.

How long did that take?

Hmm, I would have to guess around a hundred hours or so. The problem is I never had more than about 3 hours to work on it at any one time.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Aug 2014, 02:01
by zero-one
This is awsome Sprts, just a few questions.

The Empty weight for the F-35A is registered as 29,400 lbs, however Config 240-3 is 29,300 lbs I believe and 240-4 is less than 29,100 if Im not mistaken,

the fuel capacity is also listed as 18,200 lbs, however
Wikipedia has it at 18,498 lbs supported by a credible source

Was just wondering what your source for these figures were :mrgreen:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Aug 2014, 02:26
by KamenRiderBlade
zero-one wrote:This is awsome Sprts, just a few questions.

The Empty weight for the F-35A is registered as 29,400 lbs, however Config 240-3 is 29,300 lbs I believe and 240-4 is less than 29,100 if Im not mistaken,

the fuel capacity is also listed as 18,200 lbs, however
Wikipedia has it at 18,498 lbs supported by a credible source

Was just wondering what your source for these figures were :mrgreen:


http://www.lockheedmartin.com/us/produc ... riant.html

Their webpage lists the Fuel Capacity as 18,200 lbs as well.

I'm more willing to believe LockHeedMartin than Wikipedia in this case

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Aug 2014, 05:32
by zero-one
KamenRiderBlade wrote:http://www.lockheedmartin.com/us/produc ... riant.html

Their webpage lists the Fuel Capacity as 18,200 lbs as well.

I'm more willing to believe LockHeedMartin than Wikipedia in this case


I agree, the Wikipedia source was reportedly this one

http://www.jsf.mil/f35/f35_variants.htm

it does say the fuel capacity is 18,498 over there, and I usually just list it down as 18,500 lbs

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Aug 2014, 05:59
by KamenRiderBlade
zero-one wrote:
KamenRiderBlade wrote:http://www.lockheedmartin.com/us/produc ... riant.html

Their webpage lists the Fuel Capacity as 18,200 lbs as well.

I'm more willing to believe LockHeedMartin than Wikipedia in this case


I agree, the Wikipedia source was reportedly this one

http://www.jsf.mil/f35/f35_variants.htm

it does say the fuel capacity is 18,498 over there, and I usually just list it down as 18,500 lbs


Maybe that 298 lb difference is the emergency fuel for reserves or APU or something else, something that is not normally used for normal flight calculations

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Aug 2014, 14:12
by sprstdlyscottsmn
zero-one wrote:This is awsome Sprts, just a few questions.

The Empty weight for the F-35A is registered as 29,400 lbs, however Config 240-3 is 29,300 lbs I believe and 240-4 is less than 29,100 if Im not mistaken,

the fuel capacity is also listed as 18,200 lbs, however
Wikipedia has it at 18,498 lbs supported by a credible source

Was just wondering what your source for these figures were :mrgreen:

Given the multitude of sources and their varied values, I went pessimistic and used the higher empty weight and the lower fuel weight.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Aug 2014, 12:28
by hornetfinn
Great job, greatly appreciated! :D

I think in real world the range and endurance of F-35A will be even better as you seem to have used rather pessimistic TSFC number of 0.886 lb/lbf/hr. I think it most probably will have significantly lower TSFC as that TSFC number is more consistent with fighter engines produced in 1960s than current times. Modern (but older design) engines (like EJ200, M88) tend to have TSFC numbers of about 0.74 to 0.8 on dry thrust and I doubt F135 will be any worse than those. It might well be that F-35A has maybe even up to 25% better range/endurance than your calculations show. Or am I missing something obvious?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Aug 2014, 14:24
by sprstdlyscottsmn
hornetfinn wrote:Great job, greatly appreciated! :D

I think in real world the range and endurance of F-35A will be even better as you seem to have used rather pessimistic TSFC number of 0.886 lb/lbf/hr. I think it most probably will have significantly lower TSFC as that TSFC number is more consistent with fighter engines produced in 1960s than current times. Modern (but older design) engines (like EJ200, M88) tend to have TSFC numbers of about 0.74 to 0.8 on dry thrust and I doubt F135 will be any worse than those. It might well be that F-35A has maybe even up to 25% better range/endurance than your calculations show. Or am I missing something obvious?


No, you are not missing anything obvious. In my research I have found that TSFC is not a static value either so I had to come up with a formula that approximates how it changes with speed and altitude. I am using the publicly available figure of .886 as the base and it only gets worse from there. I always try to go pessimistic if I have incomplete data.

However I don't think it would matter RIGHT NOW as much as you think. I had to use the TSFC to generate the drag model, so if the current TSFC is lower, than the base drag would have been higher, and this would have given worse acceleration and sustained turning performance. So if the data I have is for a pessimistic value, so be it.

I have heard someone, somewhere on the threads, say that a future block will get new avionics hardware and that the new hardware will have reduced cooling needs. Less bypass air cooling the electronics means for the same fuel burn you are getting a higher trust output and thus better TSFC (more range, better acceleration, etc). It might be true, I don't know. So in the effort to "play fair" I use publicly available numbers wherever I can and conservative choices.

I'm glad you all are enjoying this. I have already started gathering Super Hornet data.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Aug 2014, 16:43
by spazsinbad
"Spurts" I guess you have this Super Hornet Performance Data?

NATOPS FLIGHT MANUAL PERFORMANCE DATA
NAVY MODEL F/A-18E/F
1 AUGUST 2006

http://info.publicintelligence.net/F18-EF-200.pdf (29.6Mb)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Aug 2014, 19:39
by sprstdlyscottsmn
I do. It has the most complex drag matrix of any flight manual I have ever seen.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Aug 2014, 03:14
by zero-one
spazsinbad wrote:"Spurts" I guess you have this Super Hornet Performance Data?

NATOPS FLIGHT MANUAL PERFORMANCE DATA
NAVY MODEL F/A-18E/F
1 AUGUST 2006

http://info.publicintelligence.net/F18-EF-200.pdf (29.6Mb)


Downloaded it loads of info, but Im a bit confused about the turn rate graph, it looks so different from the typical buldge looking ones.

30 degrees per second at 7Gs at around ~280 knots?
am I reading this correctly?

What's the altitude and laod for this?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Aug 2014, 04:01
by spazsinbad
I had to memorise the A4G NATOPS - hahah - but I'm not going to do that for a Super Hornet I'll never fly. With 408 pages - OK not all are graphs/tables/charts/whatever - it would be pleasant if you give a page number for what is being referenced by your 'turn rate' reference. Thanks. For example: Are you referring to the "TURN CAPABILITIES CHART"?

There is an explanation on the beginning page of that section which explains some stuff I hope: PAGE XI-10-1 OR the beginning of Chapter 10 (bookmark pane is helpful or use search for this string TURN CAPABILITIES CHART

Are we in the same ball park? Beginning of CH.10 is page 367 - chart referenced above is page 372.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Aug 2014, 07:00
by hornetfinn
sprstdlyscottsmn wrote:No, you are not missing anything obvious. In my research I have found that TSFC is not a static value either so I had to come up with a formula that approximates how it changes with speed and altitude. I am using the publicly available figure of .886 as the base and it only gets worse from there. I always try to go pessimistic if I have incomplete data.


Ok, thanks for the explanation. I definitely agree with your approach of going pessimistic with incomplete data. It definitely seems that F-35 is designed to have a very long range/endurance and be very maneuverable especially with A/G loads. Of course this translates to having both very long range and good maneuverability with A/A loads.

Wish you could make similar comparison with F-22... :)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Aug 2014, 07:41
by zero-one
spazsinbad wrote:I had to memorise the A4G NATOPS - hahah - but I'm not going to do that for a Super Hornet I'll never fly. With 408 pages - OK not all are graphs/tables/charts/whatever - it would be pleasant if you give a page number for what is being referenced by your 'turn rate' reference. Thanks. For example: Are you referring to the "TURN CAPABILITIES CHART"?

There is an explanation on the beginning page of that section which explains some stuff I hope: PAGE XI-10-1 OR the beginning of Chapter 10 (bookmark pane is helpful or use search for this string TURN CAPABILITIES CHART

Are we in the same ball park?


Well, its my 1st time to view this type of graph so Im seeing that the load is 2 slammers 2 sidewinders and at 10,000 feet.

but 30 deg\sec at 7Gs around 280 knots,

considering that a block 50 viper at angels 10, with 100% internal fuel and 4 missiles makes only around 18 degrees pulling 8Gs albeit at a higher speed, I think 30 deg\sec on a Rhino seems a little too high, or am I missing something?

can the Rhino pull 7Gs at those slow speeds, I know slow speed maneuvering is one of the Rhino's strong suit, but 280 knots?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Aug 2014, 07:52
by spazsinbad
I'll just post what I think is the chart to which you refer. What do you think NATOPS is all about? Misinformation? Probably eh. Bank Angle 81.8°