Best Fighter III

[Crumpp]

I am most often told that the pilot's guide is a guideline,

You won't find pilots telling you that.

However, I'm assuming that the full 50 degrees of flaps somehow help aid in lift-off at least on carriers?

Many aircraft use full flaps to shorten a take off. This is not the same thing as using full flaps to improve turning ability.

I use full flaps for STOL take off's in my airplane. It's not good for the plane or the engine but you can do it. It is expressly authorized and the instructions are given in the POH.

Turning is a different condition of flight. Remember our coefficient of lift is reduced in a climb and a portion of thrust will offset lift.

In a turn we need to not only provide lift force to offset weight but it has to meet the force required to offset centripetal force.

Full flaps are used in some instances for turning too! If you take a mountain flying course, you will learn and practice "canyon turns".

This is an emergency procedure done preferably from a cruise flight condition where you find yourself boxed in by terrain. You pull the aircraft up and bank into a climbing turn. At the top of it, add full flaps until you reverse 180 degrees and pick up speed.

The idea is not that full flaps improve your turn over other configurations. What gets pilots killed in mountain flying turns is speed. Radius is a function of speed.

Look at the chart again and compare both rates and radius:

Minimum Radius of Turn

We don't care if our rate of turn falls well below our best turn and it takes us all day to turn 180 degrees. What we care about is shortening the radius so we don't hit a mountain. Without the flaps, our airplane's rate of turn would be much better and we would make the 180 degree in much less time.

Because of our speed <cruise condition> we have too much speed and our radius will be much larger. The flaps allow us to lose the speed and make our turn with a smaller radius.

That does not mean that full flaps will show a turn improvement in fighter aircraft.

Look at the Buffalo turn test and let's do some math. The arrow's point to the data points used in the calculations.

Here is the sustained envelope with no flaps at 13,000ft:




Here is the sustained envelope with full flaps at 13,000ft:




Using the BGS system:

Radius = Vk^2 / 11.26 tan<a>

ROT = 1091 * tan <a> / Vk

Angle of bank = arc cos <a> * 1/Nz

No flaps, Nzmax turn at 140mph

Radius = (140 * .869)^2 / 11.26 * tan 63
r = 531 ft


ROT = 1091 * tan 63 / (140 * .869)

ROT = 17.59

20.5 seconds to complete 360 degrees



Full Flaps, Nzmax turn at 140mph

r = (140 * .869)^2 / 11.26 * tan 57
r = 854 ft

ROT = 1091 * tan <a> / Vk

ROT = 1091 * tan 57 / (140 * .869)

ROT = 13.8 deg/sec

26 seconds to complete a 360 degrees

The aircraft with full flaps is at a substantial disadvantage.

Stall boundary turn at Nzmax with no flaps

r = (115 * .869)^2 / 11.26 * tan 57

r = 576 ft

ROT = 1091 * tan 57 / (115 * .869)

ROT = 16.8

21.4 seconds to complete 360 degrees

Stall boundary turn at Nzmax with full flaps

r = (85 * .869)^2 / 11.26 * tan 48

r = 436 ft

ROT = 1091 * tan 48 / (85 * .869)

ROT = 16.4

21.94 seconds to complete 360 degrees

The turns are for all practical purposes are equal. Rate being the most important characteristic of a turn to a fighter, the aircraft without flaps has a slight advantage.

That is the effect of dropping full flaps. Your radius will decrease but your rate is increased because you have less Power available.

You can check the math easily with a universal turn chart. Remember all aircraft at the same angle of bank and velocity will make exactly the same turn. Even a Corsair and a Spitfire Mk XIV!





All the best,

Crumpp

 

[lesofprimus]

Man, my head hurts now, and my eyesight is blurring...

 

[Crumpp]

Sorry!

 

[Crumpp]

Except as provided in paragraph (d) of this section, no person may operate a civil aircraft without complying with the operating limitations specified in the approved Airplane or Rotorcraft Flight Manual, markings, and placards, or as otherwise prescribed by the certificating authority of the country of registry.

Federal Aviation Regulation Sec. 91.9 - Civil aircraft flight manual, marking, and placard requirements.

The Military also makes compliance with Flight Manuals, markings, and placards mandatory:





As with any Military regulation, a service member can always add to it but not take away. In other words, units can supplement the information by further restrictions. They cannot take away for example by saying, "Our unit will raise the listed dive limitations".

Those supplemental instructions must be forwarded to the appropriate authority listed in the Manual.

Technical Orders are just that, orders and not Technical guidelines or suggestions.

Only game players view these instructions as "guidelines". To pilots, me included as I am a pilot, they are mandatory and non compliance has both legal and very real safety consequences.

All the best,

Crumpp

 

[mad_max]

^^^^

Yep they sure were doing the war. Your delusional if you think these "mandatory"
orders were strictly followed. They were broken and not just a few times.

As it was on both sides. Between getting shot to death or maybe living; the "rules"
go out the window.

 

[Crumpp]

And how many hours do you have flying real airplanes before we conclude I am delusional?

Dead is dead, whether it comes from the airframe failing in mid flight because we exceeded the flutter limits, botched crash landing from engine failure, or the enemy's bullets.

There are many ways to die in an airplane that do not involve aerial combat.

All the best,

Crumpp

 

[Sgt. Pappy]

That's true but it also depends what guidelines. Some can be more important than others.

For example, you're not going to want to go past dive speed limits or G load limits because you'll be screwed either way. However, WEP limits have been gone over quite a bit during the war.

 

[Crumpp]

That's true but it also depends what guidelines. Some can be more important than others.

Hi Pappy,

I did not see your post. Your correct in that some maybe "more important" than others as their are different margins of safety on certain things on an airplane. However who is qualified to make that call? I may have mentioned this story but I know of guys who thought the flight manuals are guidelines too. They put a different oil in their motor that had the latest and greatest additive. Well the crank spun in the bearing races and now the guy is buying a new motor. About a 40,000 dollar mistake for not checking and following the guidelines. Scared the crap out of me because I used the same oil. I have different engine and it is ok to use in mine. However I changed it back to oil specified in the Flight Manual.

Go tell an A&P you want to use some WD-40 on your airplane to lube the canopy rails or control surfaces or some windex to clean your windshield.

So the question becomes who is qualified to decide what can be violated and what cannot? They are betting that they know more than the folks who designed and built the airplane.

The limitations found in the Flight Manuals are not put there on a whim. There are solid technical and engineering reasons for them. Facts are unlike a terrestrial vehicle, the margin of safety on an airplane has to be very small otherwise it just won't fly.

This is what made the Wright Brothers successful despite all the competition. They correctly chose an engine that ran at 100% of it's capacity assuming risk to shed weight. Their competition chose raw power without regard to weight.

This same formula is in use today. Unlike your car engine, which runs at ~30% capacity, all airplane engines run at 100% capacity for their maximum continuous rating. Any rating above that is over 100% of the engines power production capacity and we are stressing the motor.






Sure mechanics on all sides tinkered at the request of the pilots. It wasn't often and when it was discovered it was shut down.




All the best,

Crumpp

 

[Crumpp]

Facts are guys, to think the Flight Manual instructions are only guidelines to be routinely violated is born of a gamer's fantasy and not the reality of airplanes.

Go tell the Air Force recruiter you want to be a pilot but don't need those Flight Manuals as they are just guidelines!

All the best,

Crumpp

 

[Crumpp]

If you haven't seen the Allison memo PM me and I will give you a copy too.

 

[Sgt. Pappy]

hehe, I'm more on the fence here, Crumpp. I support your airframe guidelines but many pilots have over-WEPed it before. Just saying. I remember Charlie Fox telling me that he's overWEPed by about 30 seconds during the war.

And since we're on the gaming topic, I noticed a few things about AHII.

After playing Aces High II for quite a while, I've felt that the Spitfire VIII (1943, Merlin 66, Griffon tail, b-type arm; c-type wing) is a much heavier plane than the Spitfire IX (1942, Merlin 61, Merlin tail, b-type arm; c-type wing), and that the Spitfire XVI (1944, Merlin 266, Griffon tail, e-type arm; clipped e-type wing) is too light. I know that the Spitfire VIII has hydraulic fluid for its retractable tailwheel, extra wing fuel tanks (don't know if they self-seal) and wing strengthening but when the IX and VIII are at tare weight, there's only a 182 lb. difference. Does that hydraulic fluid really add some extra 350 lbs. + weight?

The weights are displayed as such:
Spitfire VIII: full ammo/100% fuel (124 Imp Gal) - 7807 lbs.
full ammo/25% fuel (31 Imp Gal) - 7137 lbs.
light (no ammo/fuel/bombs) - 6679 lbs.

Spitfire IX: full ammo/100% fuel (85 Imp Gal) - 7303 lbs. - should be 7445 lbs.
full ammo/25% fuel (21.25 Imp Gal) - 6843 lbs.
light - 6455 lbs.

Spitfire XVI: full ammo/100% fuel (85 Imp Gal) - 7241 lbs.
full ammo/25% fuel (21.25 Imp Gal) - 6781 lbs.
light - 6329 lbs.

Are these figures close to accurate?

 

[Soren]

Hehe, Sgt. Pappy those figures should be easy to check for yourself.

 

[Crumpp]

Hi Pappy,

You can check them yourself here:

Spitfire Performance Testing

I hope you understand that I could care less what AHII has in their game and no desire to find out.

All the best,

Crumpp

 

[Sgt. Pappy]

Yea, Soren, I've looked around all over the place, including Spitfireperformance.com but I haven't found the weights of hydraulic fluid and such.

Meh it's just a brain fart, since I'm a mad Spitfire fan.

Crumpp, do have similar charts for the running of the Merlin 66? I've been looking everywhere, and google has failed me on all occassions haha.

 

[mad_max]

Sgt. Pappy,

According to Robert Gruenhagen in his book Mustang The Story Of The P-51 Fighter
the 1650-7 has the equivalent British rating of R.M. 10 S.M. Comparable
British engines
are the Mark 65, 66, 67 and 85.

The 1650-3 was derived from the Merlin 61 and doesn't have a comparative British rating.

I have some data you may want. PM me your email if you want them.

 

[mad_max]

Crumpp,

Doesn't matter how many hours I have in a cockpit of civil aircraft. It would have to
be how many hours I have in a WW2 aircraft during the war years; in combat, which
I'm betting is the same amount as you have.

There are numerous accounts of using WEP for more than 5 min. and there are a
few with 20+ min with Merlin's. Was it normal? NO, but it was done and not one of
them said they were busted and Dishonorably Discharged. Of course we don't know how
many of them paid the price for doing it.

Then the other accounts of having bent/buckled skins wings from diving for jets or trying to
close the distance on an enemy.

There are too many accounts for them to be stories made up.

I agree that in a normal situation I'd be operating within the guidelines and Tech orders,
but if it was a life or death situation I'd be doing what had to be done. As it happened
in the war.

 

[Crumpp]

No MadMax it does matter how much experience you have in a real cockpit.

All aircraft operate under exactly the same principles whether they are Boeing 747, P51, or a Piper Cub.

Of course we don't know how
many of them paid the price for doing it.

it was a life or death situation I'd be doing what had to be done.

Exactly, only the success stories lived to tell about it.

All the best,

Crumpp

 

[Crumpp]

Let's look at accident statistics and put some perspective on the importance of following the "guidelines".






Facts are if you sidestep the proper procedures laid out in the Technical instructions for the design, it will in all probability become the cause of your accident.

Modifications outside the approved standards were rare exceptions during the war and cannot be classified as anything close to the norm. While the success stories lived to tell about we will never know how many died when their engine failed them just when they needed it the most.

Statistics tell us about 80% of those who step outside the approved procedures end up in an accident.

Good reasons why compliance with the Technical instructions is mandatory despite the fantasy of gamers.

All the best,

Crumpp

 

[Crumpp]

Crumpp, do have similar charts for the running of the Merlin 66?

I have some original spitfire documents including all the POH's for type. What similar chart are you needing?

Power? ratings? Aircraft Performance?

All the best,

Crumpp

 

[mad_max]

Oh if you really must know...I have just the right amount of hours in Civil Aircraft
to be dangerous. 225.5 hours in a Cessna. Still has no bearing on a life or death
struggle in WW2 air combat. They did what needed to be done.

Posting all the Civil aircraft data and such means nothing for the gents in combat.
We all know the largest percentage of accidents are caused by pilot error.