Operational Performance Comparison: Viper, Beagle and Stubby

sprstdlyscottsmn · by **sprstdlyscottsmn** » 31 Dec 2014, 09:54

That's big news to me. It tells me I was rather conservative with transsonic wave drag. I was off by over 7%, which is huge for engineering. I wish I had that data when I was starting.

hornetfinn · by **hornetfinn** » 31 Dec 2014, 11:39

It has been stated that F-35 burns about 4,600lb fuel in an hour while cruising with combat load. If it does so by cruising at Mach 0.94, then the range figures seem to be extremely conservative.

optimist · by **optimist** » 31 Dec 2014, 13:18

hornetfinn wrote:It has been stated that F-35 burns about 4,600lb fuel in an hour while cruising with combat load. If it does so by cruising at Mach 0.94, then the range figures seem to be extremely conservative.

AFAIK the range figures are for a specific mission and covers various altitudes, speeds and has afterburner as well in a dogfight on the way home

hornetfinn · by **hornetfinn** » 31 Dec 2014, 14:28

Very true optimist. Maybe instead of conservative, I should've said they are realistic. Problem is that many people think that these range figures are comparable to some other aircraft where the max range figures are truly max range figures in perfect conditions without use of AB or any combat maneuvering. I see F-35 having extremely long range compared to aircraft it's replacing and most other fighter aircraft also.

sprstdlyscottsmn · by **sprstdlyscottsmn** » 31 Dec 2014, 16:16

the 4600pph had a very specific speed, altitude, and payload (.75M, 32,000ft, and 2500lb). This was also listed as being the max endurance speed (induced drag and parasite drag are equal). That was a very critical piece of info as it allowed me to estimate the Cdo.

hornetfinn · by **hornetfinn** » 02 Jan 2015, 07:30

Thanks Spurts, that explains it perfectly. Can you tell where those specs (altitude, speed and payload) are from?

sprstdlyscottsmn · by **sprstdlyscottsmn** » 03 Jan 2015, 03:07

hornetfinn wrote:Thanks Spurts, that explains it perfectly. Can you tell where those specs (altitude, speed and payload) are from?

Originally posted here, link in post doesn't really go anywhere anymore however.

bumtish wrote:Post03 Oct 2011 15:03

Hi guys,

Energo wrote this on the Ares Blog. Is it of any help? Or perhaps if Energo tuned in on the thread?

"According to Col. Rob Simms at the US embassy in Oslo the F-35s optimal cruise is around 32000 feet and 0.75 mach where it burns about 4600 pph. Simplified this gives about 4 hours of fuel or 1600+ nm effective range (3000+ km) on internal fuel -- still with a 2500 pound internal tactical loadout."

http://www.aviationweek.com/aw/blogs/de ... 234d227276

viewtopic.php?p=205043#205043

eskodas · by **eskodas** » 03 Jan 2015, 03:13

Source link isn't working, here's the cached. http://web.archive.org/web/201108120449 ... 234d227276

sprstdlyscottsmn · by **sprstdlyscottsmn** » 03 Jan 2015, 03:25

arrow-nautics wrote:
Is Spurts your call sign? (I know, likely a dumb question)

Oops, I missed this on the first pass through. I was never fortunately enough to be a military pilot (despite wanting to fly F-16s since I was 6). "Spurts" however was given to me in the same manner as a call-sign.

Back in the day...
viewtopic.php?f=36&t=10031
I hung on every word Gums, johnwill, and Roscoe would share with me. So naturally when johnwill complains about the length of my "name" and Gums decides to shorten it... well then a "callsign" it became.

smsgtmac · by **smsgtmac** » 03 Jan 2015, 05:50

sprstdlyscottsmn wrote:That's big news to me. It tells me I was rather conservative with transsonic wave drag. I was off by over 7%, which is huge for engineering. I wish I had that data when I was starting.

That's not data without a source or altitude. I'd be very surprised if there IS a reliable source for it as AFAIK that KPP data has not been publicly released. No need to factor it into your equations yet. :wink:

Added 3 Jan: I should probably add that the 'Bowman Paper' makes reference (pp 7-8) to a mil power cruise capability of "greater" than .96 Mach 'threshold' and M1.0 'objective' with "internal weapons only" at 30K ft and at an unspecified weight/fuel load. Given that Air Vice Marshall Osley came close to stating the F-35A's trans-sonic acceleration KPP as also described in the Bowman Paper, Bowman data could be seen as increasingly credible, but still incomplete.

dee · by **dee** » 06 Jun 2015, 04:31

sprstdlyscottsmn wrote:Alright, here it is! I will take some of the initial feedback on this before doing the SHornet, ASHornet, and Sea comparison. There were several times where the performance results surprised me (both high and low) for all the aircraft. I welcome technical/process questions and constructive criticism about the layout and such. Enjoy!

Would you permit me to copy and post this on another blog? I would do so and credit you as the author of course.

Dee

sprstdlyscottsmn · by **sprstdlyscottsmn** » 07 Jun 2015, 18:49

dee wrote:
sprstdlyscottsmn wrote:Alright, here it is! I will take some of the initial feedback on this before doing the SHornet, ASHornet, and Sea comparison. There were several times where the performance results surprised me (both high and low) for all the aircraft. I welcome technical/process questions and constructive criticism about the layout and such. Enjoy!

Would you permit me to copy and post this on another blog? I would do so and credit you as the author of course.

Dee

Certainly, but I will let you know that part of my initial analysis has changed (not the main comparison numbers though) as it was pointed out to me that I was misinterpreting the C.G. data for the Strike Eagle. It is not highly stable and is more "neutrally" stable so it's Drag area is not as big as I had initially calculated but it is still around 16-17ft^2 IIRC. I don't have my data in front of me right now. Feel free to comment as such as I do not have a current revision of the data finished.

sprstdlyscottsmn · by **sprstdlyscottsmn** » 07 Jun 2015, 18:51

smsgtmac wrote:
sprstdlyscottsmn wrote:That's big news to me. It tells me I was rather conservative with transsonic wave drag. I was off by over 7%, which is huge for engineering. I wish I had that data when I was starting.

That's not data without a source or altitude. I'd be very surprised if there IS a reliable source for it as AFAIK that KPP data has not been publicly released. No need to factor it into your equations yet.

Added 3 Jan: I should probably add that the 'Bowman Paper' makes reference (pp 7-8) to a mil power cruise capability of "greater" than .96 Mach 'threshold' and M1.0 'objective' with "internal weapons only" at 30K ft and at an unspecified weight/fuel load. Given that Air Vice Marshall Osley came close to stating the F-35A's trans-sonic acceleration KPP as also described in the Bowman Paper, Bowman data could be seen as increasingly credible, but still incomplete.

I agree to an extent, but my intial estimation was SO pessimistic that no cruise speed higher than .92M was possible and any weight or altitude. By .9M my initial wave drag was fairly overwhelming.

quicksilver · by **quicksilver** » 08 Jun 2015, 11:17

Use of the term "cruise" is problematic. Be specific, are we talking max endurance or max range?

sprstdlyscottsmn · by **sprstdlyscottsmn** » 08 Jun 2015, 13:48

I will always use Cruise for max range. Loiter speed is max endurance. You want to Cruise to the target using the least fuel to cover the distance and then Loiter around once you get there using your lowest fuel flow possible.