 | Spit or ME ?? Rumors revealed and busted !| Aviation Discuss Spit or ME ?? Rumors revealed and busted ! in the World War II - Aviation forums; SPITFIRE TURNING DIAMETER = 1,760 feet. BF 109 TURNING DIAMETER = 1,500 ft.
This particular statistic I question.
The RAE ... |
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12-01-2006, 03:31 AM
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#76 | | Senior Member
Join Date: Jul 2005 Location: Japan
Posts: 451
| Quote: |
SPITFIRE TURNING DIAMETER = 1,760 feet. BF 109 TURNING DIAMETER = 1,500 ft.
| This particular statistic I question.
The RAE tested a Spitfire Mk I in September 1940 and found that the minimum radius of turn without loss of height at 12,000 feet was 696 ft.
For what version of the Spitfire and what version of the Bf-109 is that 1,760/1,500 comparison, I wonder? | 
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12-01-2006, 03:57 AM
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#77 | | Junior Member
Join Date: Oct 2006
Posts: 11
Country:  | At 3g DATCOM is listing at max AoA at SL
Hurricane Mk1 (7691lbs)
Speed = 162mph
Rate = 21.9dps
Radius = 621ft
Bf-109E-4T (5851lbs)
Speed = 164mph
Rate = 21.6dps
Radius = 635ft
Note the radius varies with speed generally reducing with higher speeds assuming the pilot was strong enough to pull max AoA.
I don't currently have a Spitfire Mk 1 entered into the program. A Spitfire Mk 14, but that is a totally different animal.  | |
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12-01-2006, 12:39 PM
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#78 | | Banned
Join Date: Nov 2006
Posts: 215
| Wow, 109E is dangerously close to Hurrie - the slats overcome the big wingloading deficit?
What is DATCOM? Would this program be based on reported stall #s? Clmax or Clman? Wing properties?
How does any aircaft acheive high alpha? I heard one aero engineer say that once you are into high angle it is less airfoil section and more about wingload/powerload. | |
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12-01-2006, 02:28 PM
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#79 | | Senior Member
Join Date: Jul 2005
Posts: 307
| Quote:
At 3g DATCOM is listing at max AoA at SL
Hurricane Mk1 (7691lbs)
Speed = 162mph
Rate = 21.9dps
Radius = 621ft
| That's far too high a weight for a Hurricane I. Normal loaded weight, with a variable pitch prop, was about 6,300 lbs. | |
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12-02-2006, 06:57 AM
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#80 | | Junior Member
Join Date: Oct 2006
Posts: 11
Country: | Quote:
Originally Posted by Chingachgook  Wow, 109E is dangerously close to Hurrie - the slats overcome the big wingloading deficit? | My own theory is the slats were more an an anti-spin device since they don't increase the lift until you are at a high Alpha. Don't forget at the AoA where the slat is working the center wing is stalled and not producing a lot of lift. Of course exceed this and you get a violent spin entry. Quote:
Originally Posted by Chingachgook What is DATCOM? Would this program be based on reported stall #s? Clmax or Clman? Wing properties? | We got tired of anecdotal evidence producing fantasy aircraft. After using DATCOM the best key phrase to describe it is “brutally honest”. It’s about 4000 pages of hard core math. https://oscommerce.darcorp.com/produ...a38a9050314dea
The purpose of the Datcom (Data Compendium) is to provide a systematic summary of methods for estimating basic stability and control derivatives. The Datcom is organized in such a way that it is self-sufficient. For any given flight condition and configuration the complete set of derivatives can be determined without resort to outside information. The book is intended to be used for preliminary design purposes before the acquisition of test data. The use of reliable test data in lieu of the Datcom is always recommended. However, there are many cases where the Datcom can be used to advantage in conjunction with test data. For instance, if the lift-curve slope of a wing-body combination is desired, the Datcom recommends that the lift-curve slopes of the isolated wing and body, respectively, be estimated by methods presented and that appropriate wing-body interference factors (also presented) be applied. If wing-alone test data are available, it is obvious that these test data should be substituted in place of the estimated wing-alone characteristics in determining the lift-curve slope of the combination. Also, if test data are available on a configuration similar to a given configuration, the characteristics of the similar configuration can be corrected to those for the given configuration by judiciously using the Datcom material.
On top of this you’ll need Dr Roskam’s enhancements. https://oscommerce.darcorp.com/produ...products_id=42 Quote:
Originally Posted by Chingachgook How does any aircaft acheive high alpha? I heard one aero engineer say that once you are into high angle it is less airfoil section and more about wingload/powerload. | Max AoA is where te wing stalls. Wingloading and power effects also effect turn rates/radius. | |
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12-02-2006, 02:16 PM
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#81 | | Senior Member
Join Date: Feb 2005
Posts: 5,024
| Very interesting Sarge714, however on top of this I've got to ask; Are you an educated aerodynamicist ?
__________________  We have built a total of about 1250 of this aircraft (Me-262), but only fifty were allowed to be used as fighters - as interceptors. And out of this fifty, there were never more than 25 operational. So we had only a very, very few.
- Adolf Galland | |
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12-02-2006, 08:34 PM
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#82 | | Banned
Join Date: Nov 2006
Posts: 215
| Sarge,
How close is DATCOM calculations to known real world test results? If you put data in for a Cessna 152 how well do the numbers line up with the real aircrafts performance? | |
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12-03-2006, 01:37 AM
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#83 | | Junior Member
Join Date: Oct 2006
Posts: 11
Country: | Quote:
Originally Posted by Chingachgook Sarge,
How close is DATCOM calculations to known real world test results? If you put data in for a Cessna 152 how well do the numbers line up with the real aircrafts performance? | Roskam has a data list for several aircraft that you can compare against. The DATCOM manual compares the quality of each computed stability derivative. Most fall in the instrument noise from flight test. A couple derivatives have larger margins. For example control force has a 30% margin. And subsonic calc's are more accurate than trans/super sonic.
The most impressive I've worked with so far was the Zero roll rate. The data in NACA 868 says is in the 55dps at 160mph. DATCOM says the A6M5 could do 109dps at 183 mph (30 lbs of stick force).
If you watch this video of Steve Hinton flying the A6M5 it supports the DATCOM roll rate. YouTube - Mitsubishi A6M Zero airshow
DATCOM has been a good tool to help separate the BS/Propaganda from reality. | |
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12-03-2006, 02:34 PM
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#84 | | Banned
Join Date: Nov 2006
Posts: 215
| This may be why Hinton rated Zero just behind Bearcat among his fav warbirds when I talked with him. His Zero has no wing gunz - that may have some effect? | |
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12-03-2006, 02:41 PM
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#85 | | IP/Mech THE GREAT GAZOO
Join Date: Apr 2005 Location: Colorado, USA
Posts: 13,587
Country: | Good information Sarge - but as discussed here before, what happens to that roll rate at 300+ mph?
__________________ "IF ITS RED OR DUSTY, DON'T TOUCH IT"  | |
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12-03-2006, 11:48 PM
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#86 | | Junior Member
Join Date: Oct 2006
Posts: 11
Country: | Quote:
Originally Posted by FLYBOYJ Good information Sarge - but as discussed here before, what happens to that roll rate at 300+ mph? | DATCOM shows for the A6M5 about 57dps at 300mph IAS at SL. The NACA data shows about 42+ dps for the same speed at 10,000ft. | |
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12-10-2006, 07:02 AM
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#87 | | Junior Member
Join Date: Nov 2006
Posts: 9
Country:  | the japs called the bau whispering death | |
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12-10-2006, 09:13 AM
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#88 | | Minister of Whoopass
Join Date: Jul 2004 Location: Long Island Native in Mississippi
Posts: 13,306
Country: | Its Japanese, not Japs... Please refrain from using derogatory racial slang terms here...
__________________  "After That Second Kill, I Knew It Was Time To Get The Hell Outta There..."-- Lt. William Northrop Case
To See My IL2 Sturmovik Video Tribute to My Grandfather, Click Here: http://www.youtube.com/watch?v=HtzN5RuNNJk | |
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12-10-2006, 10:35 AM
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#89 | | Master of Ewes
Join Date: Dec 2003
Posts: 19,959
Country: | he wouldn't have ment it to cause any offense we use the term readily and freely over here without compalaint.............
__________________ 
"Reminds me of the time I sank the Tirpitz" comments a Spitfire pilot, "One pass of course, old boy." | |
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12-10-2006, 12:21 PM
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#90 | | Minister of Whoopass
Join Date: Jul 2004 Location: Long Island Native in Mississippi
Posts: 13,306
Country: | Thats not true, everytime that word is used I say something... Its derogatory and demeaning and has no use here....
__________________ "After That Second Kill, I Knew It Was Time To Get The Hell Outta There..."-- Lt. William Northrop Case
To See My IL2 Sturmovik Video Tribute to My Grandfather, Click Here: http://www.youtube.com/watch?v=HtzN5RuNNJk | |
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