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Blutarski2004
03-22-2005, 01:09 PM
Just had some thoughts on the importance of roll rate. This is what roll rate means approximately -

30 deg bank = 1.15G turn (barely turning)
45 deg bank = 1.4G turn
60 deg bank = 2G turn
70 deg bank = 3G turn
75 deg bank = 4G turn
80 deg bank = 6G turn

Assume an a/c flying at an airspeed which = a 60 deg/sec max roll rate. Ignore inertia and assume a constant roll rate value for the sake of simplicity (inclusion of inertia would make the results worse). In the first second of the roll, the a/c will display an AVERAGE bank angle of only 30 deg (0 to 60 in one second). After two seconds time has elapsed, the average bank angle is only 45 deg. Only in the 3rd second of elapsed time is the a/c turning really hard (4 to 6 G's).

An a/c attacking from behind will basically have at least 2 seconds to close range. A 100 mph overtaking speed will mean closing the range by 100 yards before the target a/c can even start to really maneuver. In the 3rd second of time, the target a/c is just starting to pull a hard turn, but the attacking a/c can stil line up with a much looser turn and will also close the range by an additional 50 yards.

That's why a bounce was so dangerous. If not detected at all, you were dead meat. If the attacking a/c was less than 500 yds (300 yds effective firing range + 150 yards closure after detection) when first detected, you were probably still dead meat. You had to detect the attacker when he was still at least a half mile away in order to have a good chance of evading the attack.

It's so interesting to analyse the nuts and bolts of aerial combat.

fherathras
03-22-2005, 02:10 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Blutarski2004:
Just had some thoughts on the importance of roll rate. This is what roll rate means approximately -

30 deg bank = 1.15G turn (barely turning)
45 deg bank = 1.4G turn
60 deg bank = 2G turn
70 deg bank = 3G turn
75 deg bank = 4G turn
80 deg bank = 6G turn

. <HR></BLOCKQUOTE>

That depends on the lift of the aircraft in question.

but yes, bananas tastes **** http://forums.ubi.com/images/smilies/16x16_smiley-indifferent.gif

LEXX_Luthor
03-22-2005, 02:21 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>The Ki-43 was, in some ways, more dangerous to deal with than the A6M, chiefly
because it had a better rate of roll...
:
:
In practice, Oscar and Zero drivers both generally preferred to snap up into tight loops when bounced... <HR></BLOCKQUOTE>

Blutarski2004
03-23-2005, 08:42 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by fherathras:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Blutarski2004:
Just had some thoughts on the importance of roll rate. This is what roll rate means approximately -

30 deg bank = 1.15G turn (barely turning)
45 deg bank = 1.4G turn
60 deg bank = 2G turn
70 deg bank = 3G turn
75 deg bank = 4G turn
80 deg bank = 6G turn

. <HR></BLOCKQUOTE>

That depends on the lift of the aircraft in question.

but yes, bananas tastes **** http://forums.ubi.com/images/smilies/16x16_smiley-indifferent.gif <HR></BLOCKQUOTE>

..... Actually not so.

Any two aircraft at the same bank angle and speed will turn in exactly the same manner. Both turn radius and rate of turn values will be exactly the same.

Going further along my original topic, this might be helpful in picturing what is happening under various G turn conditions. Assume the a/c in question is at 280 mph. Approximate rates of turn are:

30 deg bank = 1.15G turn = 2.5 deg/sec
45 deg bank = 1.4G turn = 4.5 deg/sec
60 deg bank = 2G turn = 8 deg/sec
70 deg bank = 3G turn = 13 deg/sec
75 deg bank = 4G turn = 20 deg/sec
80 deg bank = 6G turn = 25 deg/sec

More evidence as to why a bounce was so dangerous. Counting the seconds after becoming aware of the bounce, the target a/c (60 dge/sec max roll rate at 280 mph) can turn:

after 1st sec: 2.5 deg total (all approx)
after 2nd sec: 22.5 deg total
after 3rd sec: 47.5 deg total

Tooz_69GIAP
03-23-2005, 09:35 AM
How is this a definition of Roll Rate?? You are discussing the forces enacted on the airframe by the rate of turn at a given angle of bank.

Blutarski2004
03-23-2005, 09:40 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Tooz_69GIAP:
How is this a definition of Roll Rate?? You are discussing the forces enacted on the airframe by the _rate of turn_ at a given angle of bank. <HR></BLOCKQUOTE>

..... Perhaps it was not compeltely clear. It is a consideration of the time required for a given a/c of certain roll rate characteristics to roll into a maximum turn rate bank angle and what degree of turn can be accomplished while doing so.

AWL_Spinner
03-23-2005, 09:55 AM
Absolutely Toonz_69GIAP.

Given the pilot's position in the centre of the longitudinal rotational plane, rolling without turning will hardly induce any G.

You could merrily whizz round and round around your longitudinal axis until you made yourself very dizzy but you're not going to load yourself up with much G if that's the only rotational plane you're working.

Positive G comes when, having rolled your wings perpendicular to your desired direction of travel, presuming that desired direction isn't just "up", you pull back on the stick - i.e. trying to point the nose of the aircraft somewhere other than it's currently going.

Just rolling and rolling and rolling leaves the nose pointing exactly where it was before you decided to make yourself barf.

Roll rate is of chief importance in rotating the aircraft longitudinally so the elevators can most effectively move the nose through the desired turning arc. Hence it's importance in combat.

In effect G is a function of elevator effectiveness with regard to your airframe's velocity, not aileron effectiveness ("roll rate").

Some mixed terminology in this thread. EDIT: I see it's now been tidied up a little but still, ROLL RATE in itself has little relation to G.

RATE OF TURN on the other hand, degrees per second through a turning arc, that's what builds the G. These are not the same degrees per second as defined in the roll rate.

With regard to the initial post, there's importance in control input order dependant on your aircraft match-up - when bounced you'd mebbe perform something like a split-S in a high roll-rate a/c ie. ailerons first to put yourself into the desired turning plane and then full back-stick. Whereas in an a/c with crappy roll-rate and decent elevators you'd maybe just snap up into a loop as described above.

Blutarski2004
03-23-2005, 11:51 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by AWL_Spinner:
Absolutely Toonz_69GIAP.

Given the pilot's position in the centre of the longitudinal rotational plane, rolling without turning will hardly induce any G.

You could merrily whizz round and round around your longitudinal axis until you made yourself very dizzy but you're not going to load yourself up with much G if that's the only rotational plane you're working.

Positive G comes when, having rolled your wings perpendicular to your desired direction of travel, presuming that desired direction isn't just "up", you pull back on the stick - i.e. trying to point the nose of the aircraft somewhere other than it's currently going.

Just rolling and rolling and rolling leaves the nose pointing exactly where it was before you decided to make yourself barf.

Roll rate is of chief importance in rotating the aircraft longitudinally so the elevators can most effectively move the nose through the desired turning arc. Hence it's importance in combat.

In effect G is a function of elevator effectiveness with regard to your airframe's velocity, not aileron effectiveness ("roll rate").

Some mixed terminology in this thread. EDIT: I see it's now been tidied up a little but still, ROLL RATE in itself has little relation to G.

RATE OF TURN on the other hand, degrees per second through a turning arc, that's what builds the G. These are not the same degrees per second as defined in the roll rate.

With regard to the initial post, there's importance in control input order dependant on your aircraft match-up - when bounced you'd mebbe perform something like a split-S in a high roll-rate a/c ie. ailerons first to put yourself into the desired turning plane and then full back-stick. Whereas in an a/c with crappy roll-rate and decent elevators you'd maybe just snap up into a loop as described above. <HR></BLOCKQUOTE>

..... I never imagined this would get so confusing. A very common counter to a bounce from astern was to turn into the attack. In order to turn hard, the target a/c must first roll to a suitable bank angle. Banking is an essential part of the control input necessary in performing a turn (or a split-S for that matter). My intent was simply ro demonstrate the vulnerability of an a/c to a bounce when it had even a moderate roll rate performance - i.e., it needed about 3 seconds execute a meaningful counter-maneuver.

As far as a sharp sudden loop goes, it was certainly a valid counter for those a/c capable of performing it. But that was not my focus.

Blackdog5555
03-23-2005, 11:55 AM
Very interesting data..would be interesting to see if OLEG uses a similar table in his program algorithms for blackouts. //// For some reason Oleg's BO model will have the pilot BO while rolling in a dive. In level filght you sometimes redout or BO in a roll. . maybe because of Yaw?. Some (most)planes (P-38) dont roll logitudinally because of yaw.
But yes, Being able to spot a plane as soon as possible was criticle. I've read pilots accounts of the value of haveing a guy with "Eagle Eyes" in your flight. Some guys were better at picking out enemy a/c better than others. and getting the 2 second head start meant all the difference in the world. So a guy with a good eye was worth his weight in gold. The Golden rule was "NEVER FLY IN A STRAIGHT LINE FOR MORE THAN 15 SEC." As we all know, most dangerous attacks happened by being "bounced" from an unseen a/c. Good post. BD