Saab Draken WHIF Ideas

[Weaver]

Two-seat Drakens had small ventral fins at mid-wing:

Not the Danish TF-35's. I haven't been able to find out why, though, as both Swedish and Finnish trainer Drakens did.

The small ventral mid wing fins were added for stability. The danish TF-35s had the long rear fuselage, which gave the necessary stability needed for a trainer front. So no mid wing fins on the danish TF-35.

So the combination of ventral fins and a long rear fuselage might give you enough side area for a raised cockpit area, suitable for a stepped-seat trainer or a fighter with a bubble canopy and a bigger radar.

Well - almost. A bigger radar was tested in a wind tunnel, and found to severely deteriorate not only the longitudinal stability, but also the so called zero resistance, or, as we say in automotive the Cw-value. The twoseater canopy did not, it only affected the longitudinal stability somewhat, and one should remember that the Swedish and Finnish Draken trainers flew a lot without these ventral fins as well. They were prefered as they improved the stall exit characteristics, but the aircraft was still more stable without them than any Starfighter was. Especially in the transsonic regime.

The swivel chair I'm sitting on right now is probably more stable at transonic speeds than a Starfighter. No, I'm not going to prove it.

Not sure what you mean by zero resistance/Cw-value? Is it the drag from cross-sectional area?

[Pellson]

The swivel chair I'm sitting on right now is probably more stable at transonic speeds than a Starfighter. No, I'm not going to prove it.

Not sure what you mean by zero resistance/Cw-value? Is it the drag from cross-sectional area?

I have to admit it is somewhat tempting to ask you to prove the stability of your chair in the transsonic regime.. 

Anyway - Aerodynamic resistance for an aircraft consists of two parts:
- the zero resistance, or inherent drag. Thats what the aircraft would experience if it fell through the atmosphere without having to lift itself, or fly. This comes from the design, shape etc
- the induced resistance, i.e the resistance that is indiced by the lifting devices on the aircraft, like wings, flaps etc. This varies with attitude, deployment of flaps, brakes etc.
Together they form the total aerodynamic resistance.

In our case above, the bigger radome increased the zero resistance while the induced resistance wasn't affected. Are you with me?

[Rheged]

The swivel chair I'm sitting on right now is probably more stable at transonic speeds than a Starfighter. No, I'm not going to prove it.

Not sure what you mean by zero resistance/Cw-value? Is it the drag from cross-sectional area?

I have to admit it is somewhat tempting to ask you to prove the stability of your chair in the transsonic regime.. 

Now that I would like to see........a trans sonic swivel chair!!

   From what ridiculously little I know about the trans sonic stability of the Starfighter, but having considerable experience of swivel chairs at slow speed,   there is an arguable case that the chair  would win!

[Weaver]

The swivel chair I'm sitting on right now is probably more stable at transonic speeds than a Starfighter. No, I'm not going to prove it.

Not sure what you mean by zero resistance/Cw-value? Is it the drag from cross-sectional area?

I have to admit it is somewhat tempting to ask you to prove the stability of your chair in the transsonic regime.. 

Anyway - Aerodynamic resistance for an aircraft consists of two parts:
- the zero resistance, or inherent drag. Thats what the aircraft would experience if it fell through the atmosphere without having to lift itself, or fly. This comes from the design, shape etc
- the induced resistance, i.e the resistance that is indiced by the lifting devices on the aircraft, like wings, flaps etc. This varies with attitude, deployment of flaps, brakes etc.
Together they form the total aerodynamic resistance.

In our case above, the bigger radome increased the zero resistance while the induced resistance wasn't affected. Are you with me?

Right, gotcha - the zero resistance is therefore a combination of cross-sectional area, skin friction etc....

So yeah, of course a bigger radar would increase zero resistance because it would mean more surface area and a greater cross-section. On the other hand, the increased length (assuming a nice, pointy radome) would improve fineness ratio and thereby lower transonic drag. Trade-offs, trade-offs...

Have to say, I've always liked the idea of ventral fins under a delta wing. They're not blanked by either the fuselage or wing at high angles of attack, so they should improve directional stability, which should improve stall behavior (devil's in the details, of course).

[Jesse220]

How about a Redesigned Drakken as a 6th generation stealth fighter with twin tails, and VTOL capabilities like the F-35?

[jcf]

Two-seat Drakens had small ventral fins at mid-wing:

Not the Danish TF-35's. I haven't been able to find out why, though, as both Swedish and Finnish trainer Drakens did.

The small ventral mid wing fins were added for stability. The danish TF-35s had the long rear fuselage, which gave the necessary stability needed for a trainer front. So no mid wing fins on the danish TF-35.

So the combination of ventral fins and a long rear fuselage might give you enough side area for a raised cockpit area, suitable for a stepped-seat trainer or a fighter with a bubble canopy and a bigger radar.

Well - almost. A bigger radar was tested in a wind tunnel, and found to severely deteriorate not only the longitudinal stability, but also the so called zero resistance, or, as we say in automotive the Cw-value. The twoseater canopy did not, it only affected the longitudinal stability somewhat, and one should remember that the Swedish and Finnish Draken trainers flew a lot without these ventral fins as well. They were prefered as they improved the stall exit characteristics, but the aircraft was still more stable without them than any Starfighter was. Especially in the transsonic regime.

The swivel chair I'm sitting on right now is probably more stable at transonic speeds than a Starfighter. No, I'm not going to prove it.

Not sure what you mean by zero resistance/Cw-value? Is it the drag from cross-sectional area?

The Starfighter is very stable at transonic speeds, it was designed to be so.
All of the continual whinging about the Starfighter ignores the fact that the
majority of the German losses were pilot error due to poor training -  their
loss rate with the F-84F was just as bad and for the same reason, number two
was weather - something that effects all aircraft, number three was the J79
engine.
There's nothing inherently wrong with the Starfighter and the G version was
developed specifically for the low level strike role.

[Pellson]

The Starfighter is very stable at transonic speeds, it was designed to be so.
All of the continual whinging about the Starfighter ignores the fact that the
majority of the German losses were pilot error due to poor training -  their
loss rate with the F-84F was just as bad and for the same reason, number two
was weather - something that effects all aircraft, number three was the J79
engine.
There's nothing inherently wrong with the Starfighter and the G version was
developed specifically for the low level strike role.

No one has discussed the Starfighter losses (which actually were rather similar to most first generation M2 fighters), but the Starfighter snaking has been described by several pilots, among them Bee Beaumont.
That said, I think the Starfighter provided good service for many years. It had its vices, but also qualities, as did its European counterparts. The Draken, f.i, superstalled relatively easily, and that was something that couldn't be corrected but had to be mitigated by pilot training. The MiG-21, especially the later versions, had serious CoG issues but still performed admirably in Vietnam, f.i.

Basically, no one is claiming the Starfighter was bad. But snake it did.

[jcf]

The Starfighter is very stable at transonic speeds, it was designed to be so.
All of the continual whinging about the Starfighter ignores the fact that the
majority of the German losses were pilot error due to poor training -  their
loss rate with the F-84F was just as bad and for the same reason, number two
was weather - something that effects all aircraft, number three was the J79
engine.
There's nothing inherently wrong with the Starfighter and the G version was
developed specifically for the low level strike role.

No one has discussed the Starfighter losses (which actually were rather similar to most first generation M2 fighters), but the Starfighter snaking has been described by several pilots, among them Bee Beaumont.
That said, I think the Starfighter provided good service for many years. It had its vices, but also qualities, as did its European counterparts. The Draken, f.i, superstalled relatively easily, and that was something that couldn't be corrected but had to be mitigated by pilot training. The MiG-21, especially the later versions, had serious CoG issues but still performed admirably in Vietnam, f.i.

Basically, no one is claiming the Starfighter was bad. But snake it did.

"Snaking" is an oscillation in yaw, the nose laterally "hunts" across the direction of flight.
It's an irritation not a critical issue and easily damped.

[Pellson]

The Starfighter is very stable at transonic speeds, it was designed to be so.
All of the continual whinging about the Starfighter ignores the fact that the
majority of the German losses were pilot error due to poor training -  their
loss rate with the F-84F was just as bad and for the same reason, number two
was weather - something that effects all aircraft, number three was the J79
engine.
There's nothing inherently wrong with the Starfighter and the G version was
developed specifically for the low level strike role.

No one has discussed the Starfighter losses (which actually were rather similar to most first generation M2 fighters), but the Starfighter snaking has been described by several pilots, among them Bee Beaumont.
That said, I think the Starfighter provided good service for many years. It had its vices, but also qualities, as did its European counterparts. The Draken, f.i, superstalled relatively easily, and that was something that couldn't be corrected but had to be mitigated by pilot training. The MiG-21, especially the later versions, had serious CoG issues but still performed admirably in Vietnam, f.i.

Basically, no one is claiming the Starfighter was bad. But snake it did.

"Snaking" is an oscillation in yaw, the nose laterally "hunts" across the direction of flight.
It's an irritation not a critical issue and easily damped.

I was not aware of the definition of "snaking" as you describe it. Thanks for sorting me out on this. And I'm not trying to be smart, I really do appreciate when I get to learn linguistic nuances. 

The "hunting" was, as you point out, not really dangerous, but annoying, and it did persist even if the bigger fin, introduced on the two seater and carried over to the F-104G, improved it somewhat, at least as far as I have been told by Danish and Norwegian pilots.