I'm just wondering if the unability to attain high slip angles is because the ailerons weren't very effective in most of these planes? If so, you should be able to do it a lot better in the Fokker DVII ? I'm at work right now, so I can't test this...

Great to see the old Udet footage again though!

Just to be clear, I know nothing, well very little.

Wouldn't a planes weight to lift ratio affect how well a plane slips and this might be a factor with early planes, hi lift/low weight ?

Thanks all for your replies, particularly Gunloon. My actual hands on experience is mostly with Gliders, including the Blanik, K8, K13 Gliders. And all too brief hands on in a Janus. Brilliant. Interestingly check out this vid http://www.youtube.com/watch?v=5t7xnls2w5k. Some of the comments mirror those on our forum!

I think we should be careful, in general, to think that modern flight characteristics also apply to WWI aeroplanes. A lot of progress has been made in handling and aerodynamics since then. They were difficult beasts to handle and often flight characteristics weren't foremost in the minds of designers.

VERY interesting thread, by far the best in this forum!

I don't really look at it from an aeronautical engineering point of view, I make the distinction between forward and side slips based upon a very simple criteria: in a side slip, the longitudinal axis of the plane stays parallel with whatever reference line you're using, and in a forward slip it does not. Yes, from a certain perspective they're aeronautically the same, but I maintain they're entirely different in a practical sense.

The side slip is used to line up on a runway (or target), adjusting laterally, with a normal or shallow glidepath.

The forward slip is used to quickly dump altitude and airspeed, and involves a steeper angle of descent. When I was learning to fly, my instructors were very clear on the differences and I was expected to be competent in each type of slip...I still have the notations in my first logbook that mention specific practice in each type, I might add.

As far as the slips not feeling right, I can't agree. I've slipped every aircraft I've flown, from Cessna 152s to Beech Barons and Piper Navajos, and even those like the Mitsubishi MU-2 where involved forward slips were frowned upon...something to do with the full span flaps interfering with the airflow or some such, I don't recall exactly.

The MU-2, dirtied up with flaps 20 degrees and gear down, with power at flight idle, would literally drop like a stone in a forward slip! It was something I would never do with passengers aboard lest their brains implode...nose way down, yawed way over, with anyone aboard practically floating in their seats...frankly, I loved it

Now, that sort of maneuver would give lots of people a coniption fit if they were there to see it (company instructors used to sedate corporate flying and the FAA come to mind), but we were in a Pony Express sort of business, very time critical, and we were expected to mix it up with heavy jets in the pattern, keep our speed up, and get in on time. We routinely flew what would be considered horribly unstabilized approaches to do this too, given the volume of traffic at Atlanta Hartsfield where we hubbed.

Most 'approved' MU-2 schools teach flying the pattern at 120 knots or so, but this would be darn near suicidal in the environment we were in; if you're closely spaced on a loaded MD-11 or Super DC-8, the wake vortices trailing behind them are quite violent, enough to roll you onto your back if you're too slow...at low speeds you just don't have enough air over the flight surfaces to provide sufficient control authority to compensate.

So, we'd usually fly 250 knots in the pattern, stay above the wake turbulence until turning final, then chop power and haul the nose up in the base-to-final turn to bleed airspeed down to a safe gear/flap extension speed, throw everything out, then fly a very steep final to land past the point of the preceding heavy jet's touchdown point.

The point of this story is that with this fast flying and tight spacing, it was inevitable that we'd often end up not only high, but pretty fast when we turned final...hence the need for a deep forward slip.

Chop power, rudder to the stop, spoilers keeping you level or slightly banked depending on the lateral vector needed to keep you lined up with the runway or to compensate for a crosswind, and you'd drop out of the sky, with all that side area presented to the relative wind rapidly bleeding off excess airspeed at the same time, then straighten up to emerge at the flare doing a mere hundred knots or less for touchdown. It was very exhilarating, and worked beautifully.

And that's how slips in ROF feel to me; I get the same sort of rush, the same giddy feeling as I used to...so shoot me...it honestly feels just like it used to in the 3-D world

[MF] Gunloon

Hello Gunloon,
thanks for a real pilot's input, but how is that with planes that have no spoilers, air breaks (ok forget the 1 1/2 strutter) or flaps at all ?

Re the side slip thing - in all simulations (maybe apart RedBaron version 1 lol) i was astonished how the plane behaved when i used rudder and a bit of ailerons to compensate for the rudder, for flying "level" (both wings horizontally). The plane flew a bit sideways ok, wings level, bleeding away speed, but is also felt as if the tail of the plane wanted to swing back all of the time, and it almost went "elastic" when i did so. It would not simply return to the original line of flight, but would tend to go back and forth, or better left and right repeatedly. I always wanted to know whether this behaviour is realistic in any way ?

Thanks and greetings,
Catfish

My experience to the above post;

In the Dr.1 I flew, it would, but with very little oscillation about 4 wiggles. In the D.VIII, real none at all. Difference, Dr.1 no fin, D.VIII fin.

Modern planes fly very different then WW-1 planes. Most modern pilots have a hard time with airspeed, level flight and coordinated turns, just to name a few.

Hello K.-A.,
thanks a lot - so it is indeed the fin stabilizes the fuselage (and rest of the plane) in a way it will not "oscillate" (as you called it), or wiggle. So the finless planes should show at least some of this behaviour, while the "normal" planes should not. Hah, finally got it thanks !

B.t.w. i doubt that the SE5a could have used a forward slip (gas cut, elevators up) without breaking left or right sooner or later, all the way down ? But then in some historical clips you can see some shot-up and burning planes indeed go down almost horizontally "on the spot", if not intentionally. I will look and post if i find this sequence.

Thanks and greetings,
Catfish

The MU-2 was an extreme example, but I've flown and slipped J-3 Cubs, Citabrias, C-120s and so on as well...no spoilers, no flaps, fixed gear (not that any of those really matter; a maneuver is a maneuver, the extras only modify the aerodynamics). I'm just saying the gut feeling I get in ROF is the same.

I'm sorta getting the impression that some folks are entirely convinced that the FM in ROF doesn't feel 'right' and are getting somewhat irritated by my disagreement...ok, I yield and will shut up, but all the aero engineering quotes ain't going to beat me into submission and get me to reverse what I've said. If it doesn't feel right to you, swell...it doesn't. It does for me...I was just sharing my own experience.

Regarding the yawing phenomenon you mention, there is the factor of yaw instability and oscillation...I really haven't played with it much in ROF but it does exist; the V-tail Beech Bonanza was always known for its tail wiggle, for one example. Several of the planes I flew professionally, like the Beech Baron, had a bit of a 'hunting' tendency in yaw as well, where even in trimmed level flight the nose would swing a bit. That's why in almost any larger high performance airplane you'll find a yaw damper to keep that swinging in check.

Speaking of: I never flew Learjets, but my friends who did told me that without a yaw damper, the Lear could become dangerously unstable about the yaw axis...about every one of them would refuse to fly one with the yaw damper inop and considered that a grounding item. A more extreme example, again, but there it is.

The amount of instability and the tendency to oscillate varies all over the place with every aircraft, influenced by tail surface area and planform, wing loading, center of gravity, trimmed airspeed, and many other factors...but it is real, FWIW.

[MF] Gunloon

Hello Gunloon,

" ... a maneuver is a maneuver, the extras only modify the aerodynamics). I'm just saying the gut feeling I get in ROF is the same.
I'm sorta getting the impression that some folks are entirely convinced that the FM in ROF doesn't feel 'right' and are getting somewhat irritated by my disagreement...ok, I yield and will shut up, ..."

By all means, don't !! Why should you ?
I have got an entirely different impression, it seems as if this sim is the very first one that does it right !

"...
Regarding the yawing phenomenon you mention, there is the factor of yaw instability and oscillation...I really haven't played with it much in ROF but it does exist; the V-tail Beech Bonanza was always known for its tail wiggle, for one example. Several of the planes I flew professionally, like the Beech Baron, had a bit of a 'hunting' tendency in yaw as well, where even in trimmed level flight the nose would swing a bit. That's why in almost any larger high performance airplane you'll find a yaw damper to keep that swinging in check.
..."

Thanks for explaining. Maybe the Lear is especially prone because of its "rear drive", pushing (?) Maybe applying power and the jets pushing the whole airframe there is only a slight dose out of alignment necessary to get this effect working - certainly all speculation from my side.

" ...The amount of instability and the tendency to oscillate varies all over the place with every aircraft, influenced by tail surface area and planform, wing loading, center of gravity, trimmed airspeed, and many other factors...but it is real, FWIW. ..."

Hello, so it is not necessarily ONLY connected to finless planes, and RoF feels quite right here - well that's all i wanted to know - thanks a lot.

Greetings,
Catfish