F-86F NDB Approach into Mozdok.

[Justin Case]

Hello! I've made a little video showing how you may use the F-86F to fly an NDB approach in IMC.

 

As I say in the video, I don't follow RL procedures to 100%. Mostly because this is a game/simulator and I haven't got all day :)

 

This could be a bit boring but I hope that some of you will enjoy it!

[Dachs]

Nice :thumbup:

[Justin Case]

Thanks!

[Corrigan]

Very cool.

[White Owl]

I commented on the video, but I'll say the same thing here:

 

We lack any kind of "official" documentation for instrument approaches with planes that lack ILS equipment, but the method you've devised should work in any plane with an ADF, at any airfield with an NDB. (I think all the airports in the current map have NDBs lined up with the runways, don't they?)

 

Nice work.

[Justin Case]

Thank you and yes, it works anywhere. Just make sure you check the terrain in the F10 map before.

I think only Gelendzhik and Novorossiysk are missing navaids.

 

I've made this approach chart for Mozdok RW08 for RSBN and PRMG use in the MiG-21. It's incomplete and ugly but at least it explains a possible procedure and makes it understandable for someone who's never done anything like this before.

 

https://docs.google.com/file/d/0B9CtArHAgeXEY1cxejh1c2M0Q28/edit?usp=docslist_api

(I'm at a hotel right now, so I wasn't really able to upload the image in a proper way so I hope you can see it.)

 

The terrain in the near vicinity of Mozdok is also very flat but at other places with inconvenient winds, altitude discipline would be more critical. Maybe strong northeasterly winds in Nalchik forcing you to approach from the mountains.

[kontiuka]

Nice vid. Looking forward to trying it. I'm sure I'll end up in a cow field though.:)

[Corrigan]

Nice vid. Looking forward to trying it. I'm sure I'll end up in a cow field though.:)

 

When I did this with Justin here for the first time I got lost in the clouds on approach, fell out of the sky and died. Still had fun! We can't all be natural pilots. :P

[jocko417]

Having spent a few hours of my career doing real life NDB approaches into various airports, both in training and later in 3rd-tier airline operations, I must say the Sabre's instruments SUCK :) 1950s ergonomics... Or lack thereof...

 

It's one thing to have a fixed-card ADF, but quite another to have a fixed-card Heading Indicator... One can easily transpose the relative bearing picture from an ADF to a modern Heading Indicator in order to calculate a magnetic bearing, not so much when the heading indicator's compass rose is, for all intents, fixed, while the pointer rotates instead! Effectively the opposite from today's standards. Ridiculous to have to fly the airplane with one hand while "flying" the heading indicator knob with the other, just so left and right corrections make more sense on the approach!

 

Here is a period ADF approach chart for RCAF Station Marville, near the end of the Sabre era:

 

 

Note the minimum altitude is 900 feet above field elevation, and the beacon is located on the field, not aligned with the extended runway centerline.

 

This is purely a "cloud busting" procedure, designed to hopefully get you below the cloud base within sight of the airfield so you can circle to land visually. Imagine shooting the approach at night, with visibility down to a mile...

 

Being essentially a day VFR aircraft, the Sabre depended more on ground controlled radar approaches when the weather was REALLY bad, as it had no ILS or TACAN. A radio failure in bad weather would have been cause for a rather tight sphincter... ;) The GCA operators in Europe got lots of practice and were very, very good at their trade.

 

I've only flown one GCA approach, and it's interesting to be "talked" down through the cloud :)

 

After 1963 the RCAF's Sabres were replaced overseas by the CF-104, which had both TACAN and ILS capability.

[Justin Case]

Yeah...moving to the MiG-21 was a relief with RMI, DME and "ILS". Besides that it seems to be more stable to fly on instruments.

 

Though I will try not to forget to give the 86 some love every now and then.

[CoBlue]

Nice flying there Justin:thumbup: You're IFR rated in RL?

NDB approaches are truly challenging & difficult with those old instruments!

I did my own NDB app. at Sochi, NDB 06, freq. 761. Weather 800m vis in fog cloud ceiling OVC 300m...see track below.

[Justin Case]

I've made similar approaches to the one Jocko posted with other less experienced DCS players and I think they enjoyed just being able to get below a rather high cloud cover in a somewhat controlled manner.

 

Yes I am but since I passed my exam 5 years ago I've only flown raw data NDB approaches in simulators!

I'll have a look at your track on Wednesday when I get back home again :)

[wernst]

Hello! I've made a little video showing how you may use the F-86F to fly an NDB approach in IMC.

 

 

perfect, Justin - NDB approach even without DME, calculating time, sink rate and speed "free-handed", that is true IFR fidelity. IFR check passed.

 

Yes, it's annoying that neither the radio compass nor the heading indicator has a reference mark on top of the instrument.

How can I set the appropiate course on each instrument properly? Even a few degrees off may guide me into wilderness.

 

I assume you are a real pilot. I have a question.

As soon as I apply flaps in the F-86F the nose goes up distinctly and I have to trim nose down quite a bit.

This attitude is opposite what I experience in other planes (virtual and real ones)

Applying flaps in other planes have generally a nose down effect of different intensity which I compensate with trimming nose up.

Do you have any explanation for the nose up behavior of F-86F when setting flaps?

[Justin Case]

I'll have a look at your track on Wednesday when I get back home again :)

Well I completely forgot about that...but I have seen it now!

Good track keeping!

Maybe you should trim a bit more, and also do it in anticipation of flaps and gears.

 

If you fly outbound at say 300 kts for 2 minutes at 3000 feet, you can be pretty sure to end up way low very early if you fly inbound at <200 kts with descent rate of 1000ft/min.

If you instead fly outbound for 2 minutes at 200 kts and inbound at 160 kts, 1000 fpm should have you over the beacon closer to 500 feet.

This is just shooting from the hip but it gives you a nicer descent profile :)

 

How can I set the appropiate course on each instrument properly?

IIRC the compass itself seems to give a correct indication regardless how the rose is set.

If you look carefully at the top of the radio compass, there is actually a small inverted triangle there to aling with...though it's hard to see.

 

Do you have any explanation for the nose up behavior of F-86F when setting flaps?

Hmm...in some aircraft this happens due to increased downwash on the tailplane, but since the stabilator is located above the wing this is probably not the case here.

Could it be due to wing sweep? Effte? <- a member on this forum who usually knows too much about these kind of things.

[effte]

Going to make a quick educated guess here, but if the pitch-up is a correct representation of the aircraft I'd guess at two main factors:

 

The elevator in the downwash. Yes, the elevator is out of the main downwash, but there's still downwash. It's just not as intense as if the stab was in the main flow off the wing.

 

Wing planform. The flaps increase the lift over the inboard section of the wing, which is also the foremost section. The lift increases forward of the center of pressure, moving it forward and creating a pitch-up moment.

 

Could have done with a cup of coffee, so don't shoot me if I bot it all gackwards. :)

[theGozr]

In Yak9's Pitch goes down that make easier to see landing strip, gently throttling up make the plane pitch up.. I rather trim up than trim down on landing ;) There are tones of reason for. All WW2 sims got it wrong.

[wernst]

. . . The flaps increase the lift over the inboard section of the wing, which is also the foremost section. The lift increases forward of the center of pressure, moving it forward and creating a pitch-up moment.

Could have done with a cup of coffee, so don't shoot me if I bot it all gackwards. :)

 

I found earlier forum threads regarding "F-86F flaps and nose-up attitude“

http://forums.eagle.ru/showthread.php?t=127873

 

An extended description of flaps’ flight physics can be found here:

http://www.pilotfriend.com/training/flight_training/fxd_wing/use_of_flaps.htm

 

In short:

“Flaps contribute primarily to the landing approach angle by increasing the 'braking effect' of drag.

The drag is used initially to increase the approach angle without a corresponding increase in speed.”

 

Yes, that is what I 'm expecting as the main feature of flaps. Increasing the angle of descent (with better runway sight

and obstacle clearance) without increasing speed.

Other behavior than that seems to make no sense or may even be dangerous (nose up and stall)

[Lib]

(I think all the airports in the current map have NDBs lined up with the runways, don't they?)

 

Except Batumi :smilewink:

[chaos]

 

An extended description of flaps’ flight physics can be found here:

http://www.pilotfriend.com/training/flight_training/fxd_wing/use_of_flaps.htm

 

In short:

“Flaps contribute primarily to the landing approach angle by increasing the 'braking effect' of drag.

The drag is used initially to increase the approach angle without a corresponding increase in speed.”

 

I wouldn't put too much faith in what the owner of that website claims. Also, the quote doesn't make any sense to me. English is not my first language, so I might be completely mistaken, but... using flaps to increase approach angle is not the intended use-case. You should be using speedbrakes instead...

 

Interesting discussion regarding pitch-up moments while using flaps. I was taught that in high-wing aircraft (like a Cessna) you'll experience a pitch-up moment whereas in a low wing aircraft (like a Piper) you'd experience a pitch-down moment. Of course these are straight wing aircraft and so it might be different in an F-86. I'll investigate further although I'd be surprised if Belsimtek got this behaviour wrong. It's fundamental aerodynamics which all these flight-models are based on.

 

Thats one of the things I like about these sims. Besides blowing stuff up it also makes me question and get back into the theory of systems and aerodynamics. It's an educational tool as well! :D

[wernst]

... using flaps to increase approach angle is not the intended use-case. You should be using speedbrakes instead...

 

Do you really want to claim, that not the flaps but the speedbrakes of the F-86F are primarily intended for increasing the angle of approach???

What do you guess is "the intended use-case" of the flaps?

 

The speedbrakes do what the name suggests - only.

How can shape and position (on fuselage) of the speedbrakes increase the curvature of the wing in order to raise lift and reduce stall speed during approach?

[saybahluvah]

Reason for pitch-up when flaps are extended

 

The reason the aircraft pitches up when flaps are applied is because the center of lift of the wing shifts forward substantially when the flaps are extended. Since the center of gravity of the plane doesn't change, the new imbalance of forces causes pitch-up which must be trimmed out.

 

The center of lift moves forward because the flaps are on the innermost trailing edge of the wings, and since the wings are swept back, the forward portion of the wings suddenly produces more lift when the flaps are extended. More lift in the center-most/forward section of the wings without an increase in lift in the outer-most portion of the wings causes the center of lift to move forward.

 

If the flaps occupied the entire length of the wing trailing edge, then the center of lift wouldn't move anywhere near as much.

 

If the flaps were only on the outermost trailing edge of the wings (where the ailerons are), then there would be a pitch down when they are extended because the center of lift would move aft.

[chaos]

Do you really want to claim, that not the flaps but the speedbrakes of the F-86F are primarily intended for increasing the angle of approach???

What do you guess is "the intended use-case" of the flaps?

 

The speedbrakes do what the name suggests - only.

How can shape and position (on fuselage) of the speedbrakes increase the curvature of the wing in order to raise lift and reduce stall speed during approach?

 

Flaps are meant to increase Lift-coefficient thereby allowing to fly at a lower IAS and thus shortening the landing distance (amongst other things). It has absolutely nothing to do with 'angle of approach' (I assume you mean approach angle i.e. 3deg. glideslope). The fact that you may have better visibility over the nose is a byproduct and, again, has nothing to do with approach angle...

 

Speedbrakes increase drag and thereby allowing you to descend at a steeper angle with equal speed or decrease speed at constant altitude.

[wernst]

 

The fact that you may have better visibility over the nose is a byproduct and, again, has nothing to do with approach angle...

 

 

Increasing approach angle = increasing angle of approach = steeper approach = increasing angle of descent

 

you may even find more terms for the same effect.

Do you still claim flaps have nothing to do with this effect?

[Justin Case]

Increased drag enables steeper descent angels, flaps increase drag.

[chaos]

Guys...

 

I don't deny that flaps increase drag and therefore allow a steeper decent angle. The point I'm making is that this is not the primary function of a flap which some of you seem to be thinking. The flap was not designed to allow a steeper approach angle.

 

What would you do if you were established on approach, above the glideslope, with full flaps trying to re-intercept? We're talking F-86 here... not a Cessna...