Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: M0nkey_Man on January 02, 2011, 03:11:26 PM
-
One question about turning in it. Is it better to turn with or without flaps in the J ?
-
One question about turning in it. Is it better to turn with or without flaps in the J ?
Yes it does, the flaps will make u loose speed, but you get a MAJOR boost I turning only plane I recommend not using flaps in would be a typhoon
-
One question about turning in it. Is it better to turn with or without flaps in the J ?
Only use the flaps as you need them because it does burn "E". Flap usage is a feel thing that you pick up with practice. I think Ak-Ak posted basic speeds of when to deploy each set of flaps once, maybe he'll stop in a post them again just to give you an idea of where to start.
-
Badboy has posted charts on flap usage in this forum,you may want to search for it.
Basically,the first 2 notches of flaps indeed increase turn performance but any more than that and the drag penality becomes a loosing factor.
So go ahead and experiment on your own,use flaps when speeds allow but dont just drop them and wait for them to retract,you must retract them yourself if you wish to maintain your energy state.
:salute
-
One question about turning in it. Is it better to turn with or without flaps in the J ?
It really all depends on the situation. There are some times in a fight where deploying flaps to get an angle or to tighten up a turn isn't the right thing to do and there are other times where it's absolutely necessary to deploy flaps, it all depends on the situation.
If you are forced to use flaps, then use the use of flaps will greatly aid in maneuvering but as noted by Fugitive and morfiend, only use the flaps when you need them and retract them as soon as your done with your turn, don't leave them out unnecessarily.
Ideally in a fight, you never really want to deploy more than two notches of flaps but you'll find that there are some fights were you need to deploy more flaps and that's okay but remember to retract them as soon as your done.
If you use your flaps improperly, you'll find out that you're going to end up fighting more than just the enemy you're trying to shoot down.
ack-ack
-
ok thanks for the help :)
-
rule of thumb: Use as little flat as necessary to turn on one attacker. If you only use one notch for a short period you'll burn less E. If multiple attackers you better think quick. If you slow too much the others will line you up. One the other hand, when you get enough practice you"ll be able to out turn & shoot a lot of them, then raise flaps up quickly.
-
Here's Badboy's diagram Morfiend mentioned.
(http://i547.photobucket.com/albums/hh473/cactuskooler/P38LFlaps.jpg)
I also made this with Badboy's Bootstrap Calculator. It's at 25% gas, at sea level, with the big gun package in a P-38J. I believe it's reasonably accurate.
(http://i547.photobucket.com/albums/hh473/cactuskooler/38_Flap_Turn_Data_25_Big_Guns.jpg)
Learning for the first time when to use flaps is difficult to do solely from numbers and graphs though. In my opinion the best way to learn, and the way I learned, is to examine films from the 38 gurus. You can watch the needle on the flap gauge to see which flap setting they're at, then observe what kind of turn they're in and what speed they're at. Eventually I watched enough films that I could predict how they would use their flaps, at which point I had an idea how to work my own flaps.
Also, don't be afraid to stick all the flaps out when you need to, especially in a 1v1. Your plane won't fall out of the sky. It's not the best idea to do in a furball if you value your virtual life though.
(http://i547.photobucket.com/albums/hh473/cactuskooler/S_i6p4i1.jpg)
-
Rule of thumb:
If you can pull off the maneuver you want without flaps:
don't use them.
else:
use them to complete the maneuver and retract.
-
Only good thing bout a 38 and using flaps I noticed is when your at like 80mph strait up chop throttle and it flips over strait back down for an easy HO shot or rope shot. 38 awesome bird just wish I would fly it more instead of a 109
-
Here's Badboy's diagram Morfiend mentioned.
(http://i547.photobucket.com/albums/hh473/cactuskooler/P38LFlaps.jpg)
I also made this with Badboy's Bootstrap Calculator. It's at 25% gas, at sea level, with the big gun package in a P-38J. I believe it's reasonably accurate.
(http://i547.photobucket.com/albums/hh473/cactuskooler/38_Flap_Turn_Data_25_Big_Guns.jpg)
Learning for the first time when to use flaps is difficult to do solely from numbers and graphs though. In my opinion the best way to learn, and the way I learned, is to examine films from the 38 gurus. You can watch the needle on the flap gauge to see which flap setting they're at, then observe what kind of turn they're in and what speed they're at. Eventually I watched enough films that I could predict how they would use their flaps, at which point I had an idea how to work my own flaps.
Also, don't be afraid to stick all the flaps out when you need to, especially in a 1v1. Your plane won't fall out of the sky. It's not the best idea to do in a furball if you value your virtual life though.
(http://i547.photobucket.com/albums/hh473/cactuskooler/S_i6p4i1.jpg)
Thx for posting that Cactus. :aok
The diagram clearly shows the diminished returns for using "too much" flaps.
:salute
-
nice graph :aok ,like the pic too :lol ...time to go watch some film :x
-
Here's Badboy's diagram Morfiend mentioned.
(http://i547.photobucket.com/albums/hh473/cactuskooler/P38LFlaps.jpg)
I also made this with Badboy's Bootstrap Calculator. It's at 25% gas, at sea level, with the big gun package in a P-38J. I believe it's reasonably accurate.
(http://i547.photobucket.com/albums/hh473/cactuskooler/38_Flap_Turn_Data_25_Big_Guns.jpg)
Learning for the first time when to use flaps is difficult to do solely from numbers and graphs though. In my opinion the best way to learn, and the way I learned, is to examine films from the 38 gurus. You can watch the needle on the flap gauge to see which flap setting they're at, then observe what kind of turn they're in and what speed they're at. Eventually I watched enough films that I could predict how they would use their flaps, at which point I had an idea how to work my own flaps.
Also, don't be afraid to stick all the flaps out when you need to, especially in a 1v1. Your plane won't fall out of the sky. It's not the best idea to do in a furball if you value your virtual life though.
(http://i547.photobucket.com/albums/hh473/cactuskooler/S_i6p4i1.jpg)
is it just me or do those "luftwaffe" planes look like cartoon p40s?... :headscratch:
-
I also made this with Badboy's Bootstrap Calculator. It's at 25% gas, at sea level, with the big gun package in a P-38J. I believe it's reasonably accurate.
(http://i547.photobucket.com/albums/hh473/cactuskooler/38_Flap_Turn_Data_25_Big_Guns.jpg)
I suspect something was missed in the calc. Your 'no flap' minimum turn radius/max turn rate turn seems way low for 108mph stall speed.
That manuever would be close to 3g, pretty good banked turn and it should be stalling ~ 165-170mph not 108.
-
Here is some more information about the use of flaps and maneuvering in general while flying a P-38.
Hanger Flying Issue #6 (http://jamesreese.org/hangarflying/Issue6.htm)
"MANEUVERING FLAPS SHOULD BE EXTENDED ONLY LONG ENOUGH TO COMPLE PARTICULAR MANEUVER AND THE BE RETRACED IMMEDIATELY"
-Ray Meskimen (Lockheed test pilot)
Maneuvering flaps increase your lift, thus assisting you in making tighter turns. For greatest maneuverability we have found that the maneuvering flaps should be extended only long enough to complete the particular maneuver and then be retracted immediately. For example, in an effort to stay on an enemy's tail, you might feel in a tight turn the buffeting which is characteristic of an accelerated stall. You can "reef" her in and tighten your turn by lowering the maneuvering flaps until you have completed the maneuver, then retract them. By doing so immediately, little air speed is lost, and the plane is set again for maximum operations.
Don't be caught with your flaps down for any length of time in combat; the reason being that with maneuvering flaps down you can unknowingly get down to such low speeds that all the power in the world won't do you much good should you need sudden acceleration. From 25,000 feet to 35,000 feet the maneuvering flaps become increasingly helpful. Due to the thinness of the air you can't turn as sharp nor can you pull as many G's as can be done below 20,000 feet. As you go higher you find that you are stalling more frequently. You will be surprised at the increased maneuverability resulting from extending your flaps at this altitude.
ack-ack
-
I suspect something was missed in the calc. Your 'no flap' minimum turn radius/max turn rate turn seems way low for 108mph stall speed.
That manuever would be close to 3g, pretty good banked turn and it should be stalling ~ 165-170mph not 108.
I think you're misreading it. The 108 straight and level stall speed is a calculation based on cactuskooler's measured turn rate of 17.83 at 198 MPH. If you look at Badboy's EM diagram his no flaps best sustained turn is at 3.2 G at 190 MPH and you would be stalled at 185 at 3 Gs. At 165 you could only pull 2.4 Gs.
-
I think you're misreading it. The 108 straight and level stall speed is a calculation based on cactuskooler's measured turn rate of 17.83 at 198 MPH. If you look at Badboy's EM diagram his no flaps best sustained turn is at 3.2 G at 190 MPH and you would be stalled at 185 at 3 Gs. At 165 you could only pull 2.4 Gs.
I did misread it, seeing only the reference to 108mph in your tables. Having said this, IIRC the 3g stallspeed for the P-38J/L @17500 GW is approximately 165-170 per Dean's tables - but I have not fooled with P-38 calcs. I have not yet been able to see the actual notes from the October 1944 Patuxent River Fighter Pilot Convention to see what references Dean used for his tables.
I don't question the EM plot or Badboy's derivations but curious regarding the boundary conditions.
They are easy enough to derive (for my understanding) with another couple of questions
What are you using for Limit Load for a P-38J/L at 15,483 pounds and what CLmax are you using for clean config and at what Bhp? Did you derive 'eta' for efficiency at high Hp/low speed or use something like .85? Did you derive CD0 from a flight test result for 15,483 pounds @Bhp for this model at SL?
-
We fly the Aces High aircraft and time the turns. I don't know what Badboy used for his Bootstrap Calculator. I don't know why we'd be concerned with limit loads. There is a 6 G limit for the pilot. We are mostly concerned with shooting each other down. Have you tried Aces High?
-
We fly the Aces High aircraft and time the turns. I don't know what Badboy used for his Bootstrap Calculator. I don't know why we'd be concerned with limit loads. There is a 6 G limit for the pilot. We are mostly concerned with shooting each other down. Have you tried Aces High?
No, but Brooke's calcs on the internet brought me to the site because I was curious to ask how he treated the aerodynamics of high AoA and lower speed range to stall - in context of the use of Oswald efficiency, Power efficiency and the unchartered drag rise at near stall high G manuevers. IMO, Oswald efficiencies as used in the game models understates the significant increases to viscous drag which are related to angle of attack (instead of the Oswald factor associated with the smaller parasite drag of lower angles of attack).
The V-n diagrams are all about limit loads. And stated Limit loads are deceptive. For example the orginal P-51 was designed to 8G Limit/12 G Ultimate... but at 8,000 pounds for P-51A... so as the airplane grew, say to ~10K for a P-51D. As a result the Limit load reduced to (8,000*8G)/10,000=6.4g
Ergo - if 8g Nmax is used, the resulting Vc=~ 11.8% too high... = f(sqrt(8/6.4))
-
In this discussion on the use of flaps we're just looking at how different flap settings change the turn rate and radius. The 6 G limit in the diagram is the pilot limit modeled in AH not the airframe limit.
It would be interesting to know the practical effect of "significant increases to viscous drag" and if the effect is the same for all aircraft or if it would change the relative performance under your conditions.
-
In this discussion on the use of flaps we're just looking at how different flap settings change the turn rate and radius. The 6 G limit in the diagram is the pilot limit modeled in AH not the airframe limit.
It would be interesting to know the practical effect of "significant increases to viscous drag" and if the effect is the same for all aircraft or if it would change the relative performance under your conditions.
Short answer, should raise the minimum stall speed/turn radius as well as relative energy losses - and no, I don't believethat the behavior between a draggy 109 and a very clean 51 would continue in a linear fashion.. but no proof points as yet
I started a thread on discussions regarding Oswald efficiency factor. Candidly, I am a graduate aero and practising aero (and airframe structures), looong out of the biz after a stint at lockheed and Bell, but know for a fact that we did nothing related to changes in CDo due to changes (moderate to high) in angle of attack related viscous drag. Everything was focused in preliminary design on range, take off and landing performance, climb, max speed, cruise speed, and ceiling - but symmetrical flight...
I have looked at a lot of spreadsheets out there and have problems with detail assumptions - and particularly in the behavior of high throttle/fine pitch prop behavior in low relative speeds (near stall), as well as assuming Oswald efficiency estimates behave as a constant as the AoA increases to CLmax.
Summary - My thesis is that the effects are significant - and vary in the significance between a draggy beast like a 109 and a clean 51 at the bottom of the drag bucket where the high G turns are played out in the games.
-
Once you figure out what the model should be doing you can try Aces High and see how it compares. The Aces High flight model hasn't been published so I assume Brooke published something general and not specific to the Aces High flight model.
-
Once you figure out what the model should be doing you can try Aces High and see how it compares. The Aces High flight model hasn't been published so I assume Brooke published something general and not specific to the Aces High flight model.
I have no quarrel with Brooke's model or his internet publication. I came to this forum to exchange ideas.
Having said this, it is just a game but seems to have a lot of thought built into the model.
-
I didn't think you were quarreling. I don't know what's in the Aces High flight model but I'm interested in how it could be improved.