« previous next »
Pages: [1] 2   Go Down

Author Topic: Interesting test results  (Read 1097 times)

Offline bloom25

  • Silver Member
  • ****
  • Posts: 1675
Interesting test results
« on: October 22, 2000, 04:37:00 AM »
(Reposted from "Couple of quick numbers" thread on the General Discussion board.)

Ok, here are some more results from testing. I tested nearly all of the planes by the following method:
First of all, take off at a1 offline and proceed to 7k EXACTLY. Loadout was always the very top guns package, 25% fuel, NO ordinance of any kind( bombs, rockets or dts). At 7k stabilize speed at 200mph and turn off the engine, be sure not to allow the speed to be accelerating in any way, this would cause errors. CT was off (I tested with it on and it didn't seem to effect anything though.)

Here are my results:
plane: Time (seconds):
A6M5 11
109F4 21
109g10 19
c202 48
c205 52
f4u-1c 25
f4u-1d 26
190a5 26
190a8 23 *
la5 1:42
N1k 1:17
P51d 20
P47-d30 30 **
spit9 15
spit5 13
yak9u 15
typhoon 18
p38l 1:18 ***
c47  58

* 190A8 stalled at this time
** P47-d30 is unable to finish test, stalls at time stated
*** p38l will not finish test, stalled at 105 mph at the stated time.

Error: +/- 2 seconds max
___________________________

I don't want to make any conclusions at this point. The results certainly surprised me.
Please test yourself and post your results so we can average them.

------------------
bloom25
THUNDERBIRDS

Seems to me a lot of these results run counter to what you would expect.  Given that F=dp/dt, p being momentum, that the heaviest plane with the least amount of drag should perform well.  This would be the p51.  Yet it performs horribly.  The only thing I can figure is that the high wingloading is penalizing the heavy airplanes.  If this was the case I would expect the spitfires to perform very well, yet they are among the worst performers.

Perhaps someone can run this test at 300mph to 100 mph to get another set of data.  (LOL, I might just stay up and do it.   )

------------------
bloom25
THUNDERBIRDS

[This message has been edited by bloom25 (edited 10-22-2000).]
Logged

Offline RAM

  • Parolee
  • Zinc Member
  • *
  • Posts: 38
Interesting test results
« Reply #1 on: October 22, 2000, 05:34:00 AM »
Makes you think, that for sure...

I guess you did test it while trimming the plane, isnt it? (guess so as you say that the comparison with CT on was identical)
Logged

funked

  • Guest
Interesting test results
« Reply #2 on: October 22, 2000, 05:56:00 AM »
P-51 is the heaviest plane with the least drag?  You're going to have to prove that to me.  P-51 has very low parasitic drag but IIRC is nothing special in the induced drag department.  And below 175 mph or so induced drag is dominant.  Also the P-51 is far from the heaviest plane in the set even at 25% fuel load.

I'm not saying your tests or your conclusions are wrong, just that it's not as simple as you make it out to be.  You can't just say "this plane is OK, this plane is off" without doing some hard core analysis of lift and drag and gravity and momentum.  And since it is transient behavior, you're going to need to create your own sim to get meaningful theoretical predictions.

PS Did you hold the planes at 7,000 feet or did you use auto-level?  Unfortunately these are not the same thing.

[This message has been edited by funked (edited 10-22-2000).]
Logged

funked

  • Guest
Interesting test results
« Reply #3 on: October 22, 2000, 06:37:00 AM »
I'm getting 24 seconds for N1K2.  It stalls right as I hit 100 mph.  I'm guessing you used autolevel.
Logged

Offline Vermillion

  • Platinum Member
  • ******
  • Posts: 4012
Interesting test results
« Reply #4 on: October 22, 2000, 09:52:00 AM »
All the discussion about the Corsair, but no one mentions that the obvious outlying data is the C.202, C.205, and the La5FN ?

------------------
Vermillion
**MOL**, Men of Leisure
Logged

Offline hitech

  • Administrator
  • Administrator
  • *****
  • Posts: 12425
      • http://www.hitechcreations.com
Interesting test results
« Reply #5 on: October 22, 2000, 11:26:00 AM »
In the test you gents are running prop drag is a large component.

HiTech
Logged

Offline Maverick

  • Plutonium Member
  • *******
  • Posts: 13958
Interesting test results
« Reply #6 on: October 22, 2000, 02:12:00 PM »
 
Quote
Originally posted by hitech:
In the test you gents are running prop drag is a large component.

HiTech


HT,

F4U has the largest prop of all planes in his list on top of the drag from a radial engine and a larger airframe. Yet they still maintain E better than the 51?!?!?!?!

Prop drag aside I think a sleeker airframe will have less drag than a larger frontal airframe and should shed E slower. These "tests" indicate otherwise.


Mav
Logged
DEFINITION OF A VETERAN
A Veteran - whether active duty, retired, national guard or reserve - is someone who, at one point in their life, wrote a check made payable to "The United States of America", for an amount of "up to and including my life."
Author Unknown

Offline Pyro

  • Administrator
  • Administrator
  • *****
  • Posts: 4020
      • http://www.hitechcreations.com
Interesting test results
« Reply #7 on: October 22, 2000, 02:22:00 PM »
Mav, there's a lot more at work than prop diameter.  Number of blades and blade angle for example.  The problem with this particular test is that it doesn't really test what it purports to.  Airframe drag is probably the smallest factor in the results of this test.



------------------
Doug "Pyro" Balmos
HiTech Creations
Logged

Offline Maverick

  • Plutonium Member
  • *******
  • Posts: 13958
Interesting test results
« Reply #8 on: October 22, 2000, 04:14:00 PM »
 
Quote
Originally posted by Pyro:
Mav, there's a lot more at work than prop diameter.  Number of blades and blade angle for example.  The problem with this particular test is that it doesn't really test what it purports to.  Airframe drag is probably the smallest factor in the results of this test.


Pyro,

Just responding to the only variable that HT brought up.

F4U  - 4 blade prop

P51  - 4 blade prop.

P47  - 4 blade prop

Only variable in prop drag (as topic HT brought out) was the size of the prop disk diameter and blade width. The Jug had wider blade than 51 but the hog had largest overall diameter prop disk.

Airframe drag should still be a factor.

Mav
Logged
DEFINITION OF A VETERAN
A Veteran - whether active duty, retired, national guard or reserve - is someone who, at one point in their life, wrote a check made payable to "The United States of America", for an amount of "up to and including my life."
Author Unknown

Offline bloom25

  • Silver Member
  • ****
  • Posts: 1675
Interesting test results
« Reply #9 on: October 22, 2000, 06:49:00 PM »
Yes, I used auto level for all planes.  Perhaps repeating the test and only cutting the throttle instead of killing the engine will make a difference?



------------------
bloom25
THUNDERBIRDS
Logged

funked

  • Guest
Interesting test results
« Reply #10 on: October 22, 2000, 06:58:00 PM »
I commented on the other thread, looks like it is indeed mostly prop drag we are measuring.
Logged

Offline StSanta

  • Gold Member
  • *****
  • Posts: 2496
Interesting test results
« Reply #11 on: October 22, 2000, 07:44:00 PM »
Look at the size of the prop in the c202 and 205.

I did in the snapshot. My first whine: "I want a BIGGR prop on my c202!"  

Seems only way to test that kind of glide thing is to remove the prop  .

------------------
StSanta
9./JG 54 "Grünherz"
Logged

Offline bloom25

  • Silver Member
  • ****
  • Posts: 1675
Interesting test results
« Reply #12 on: October 22, 2000, 07:57:00 PM »
I did some more testing.  Here is the method I followed:

Offline, go to a1, take off on N runway.  When the plane reaches 7k, go to auto level.  Allow the plane to reach 300 mph.  Stabilize plane at 300mph at 7k.  Now very quickly chop throttle to idle.  (Stay on auto level!)  Record the time for the plane to decelerate to 100 mph.

My results for a few of the planes:

p51d 43s
f4u-1c 48s
f4u-1d 49s
n1k 50s
la5 45s
c205 37s
spit9 28s
109g10 39s

Error +/- 2 seconds maximum

This should remove the fact that the prop windmills for some of the fighters after the engine is turned off.




------------------
bloom25
THUNDERBIRDS
Logged

Offline juzz

  • Copper Member
  • **
  • Posts: 193
      • http://nope.haha.com
Interesting test results
« Reply #13 on: October 22, 2000, 10:52:00 PM »
Hands up who thinks the Spitfire really retains energy the worst of those planes tested above?
Logged

Offline RAM

  • Parolee
  • Zinc Member
  • *
  • Posts: 38
Interesting test results
« Reply #14 on: October 23, 2000, 03:41:00 AM »
 
Quote
Originally posted by juzz:
Hands up who thinks the Spitfire really retains energy the worst of those planes tested above?

And the Niks and the Hogs the best?  
Logged
Pages: [1] 2   Go Up
« previous next »