kingaltair

My Feedback: (4)

Which fuse is "widened by 0.5"? The fuse is only 3-1/4" wide, (not very wide). Is the MAN plan only 2-3/4" wide outside edge to outside edge?

Duane

UStik

Sorry, was a typo, had to be 0.25". The MAN plan shows exactly 3" wide outside. This copy is a bit distorted vertically so the fuse length dimensions are not quite accurate, but the horizontal dimensions are. (Compare also #1161, the measurements are even more accurate now and match the measurements.)

Sorry again, 3.0" in the plan was a typo as well, has to be 3.25" so fuse width is standard. (Plan is corrected now.)

UStik

The "Flop" is a modified Orion with a 1" longer nose and a 2.5" shorter tail. The tail moment arm was measured from wing trailing edge former to elevator hinge line (a "mean" hinge line). The The RCM&E Taurus has 23.5" and MAN Taurus 24.5", which is even 3"/4" more than the MAN Orion and 5.5"/6.5" more than the "Flop". (The differences are slightly exaggerated by perspective, though.)

Maybe the tail moment arm from wing trailing edge to elevator hinge line at stabilizer root is even the same as on Orion. But the forward sweep makes for a shorter effective moment arm. On Orion, the vertical tail and rudder hinge line are raked and the moment arm is longer than that of the stab. On the "Flop", the rudder hinge line is vertical and has the same moment arm as the elevator at root.

A bit guesswork. Seems span of wing and stab are like on Orion, but both incidence angles are zero and the wing is thicker (17% ?) and has less dihedral. That would qualify the model as a Taurus. The Orion ailerons are still there as well as 12" root chord, but the tip chord is even longer than on Orion what is seen on no other model. Fuselage shape is not really modified, but the engine is inverted. Still the thrust line is not that high, seems it's 2" from top, only 0.5" higher than on Taurus. (Vertical dimensions are arguable.)

Obviously, main problems were moment arms and empennage shape. Intermediate step between Orion and "true" Taurus, bashfully called "a modified version" of the Taurus, "strictly experimental", in contrast to the "final Taurus".

hILLVILLE

My Feedback: (64)

I was able to visit with the Taurus today at the Toledo show. The gentleman sitting with (a.k.a. guarding) it were very friendly and nice to talk to. They weren't really aware of all the gibber-jabber going on in this forum. It was great to see the model in person.

cygnet

My Feedback: (33)

Hi guys sorry for the slow reply W1 is 11-3/16 but you have to add 3/32 leading edge sheeting and 1/8 trailing edge square, W12 is 7-5/16 plus the 3/32 leading edge sheeting and the 1/8 trailing edge square. F 24 is 5-1/8 high and 2-13/16 wide, the over all fuse is 3-1/4 out side dimentions, hope this helps keep up the posts as us old Taurus flyiers are spell bound, by the way I'm just finishing up a scratch built Taurus its going to be electric all dope finish.

pimmnz

I may be able to clear up the '12 x 6' prop issue for you Duane, all the texts, and even supplied in the kit of the Orion, mention a 12 x 6 prop for the K&B/Veco/Lee 40/45 engines of the time. Small props and high revs are a much later aberration, to extract maximum horsepower from a small engine. Even my LA.46 likes an 11 X 6 in preference to anything smaller, and Taurus flies much better with the bigger props too.
Evan. (Purchasing wood)

UStik

cygnet, thanks a lot for the check, now we know for sure which dimensions in the plans are correct. You just verified our latest assumptions! Good luck with your build and please report how electric goes!


Adjusted now, aren't they?

pimmnz

Yep!
Evan.

UStik

Does anyone of you guys know the throw of the old Transmite servos? I'd just like to know the MAN Taurus control throws, and with the linkage geometry in the plan and the Transmite throw I could calculate them.

In the articles, Ed consistently specifies the throws as fractions of one inch, e.g. 5/16" per inch, what makes 18.2 degrees. This way he specifies both aileron (with 20% differential) and elevator (kick-up 34 deg), the latter a bit more down for outside loops. Rudder throw is not specified.

In the simulator, I have now the MAN/TF Taurus and the 1962 Nats (contest) Taurus flying (with a dummy appearence). The airfoil parameters are adjusted (approximated) so that the suspected problem occurs: hard to spin (Ed mentions it). The control throws are: aileron 20 degrees (20% differential), elevator 20 degrees (up and down) and kick-up to 40 degrees (dual-rate), rudder 45 degrees. That's the same for both versions, but the 1" more tail cone length makes much difference (much more than I expected).

The MAN Taurus has the rearward c/g location given in the plan (says 4.75" to 5" behind center leading edge). It needs the slightly rearward c/g both for level-flight trim and for spinning. Despite the elevator throw even bigger than specified and the "terrific" (as Ed calls it) rudder throw, it doesn't spin in the forward c/g position and hardly in the rearward. The Nats Taurus is a bit more stable with the forward c/g position, is still trimmed for level flight, and with the rearward c/g position spins even docile. It's a bit more dampened as well.

I wouldn't sweat the flight characteristics in the simulator too much, they are simply adjusted as descibed by Ed so they can't be completely wrong. After all Ed himself says in the articles that even each model of the same type is slightly different. Now the simulator gives us one important benefit (compared to reality): We can make two models exactly the same and then modify only one parameter (e.g. tail cone length) to assert the differences in flight behavior (e.g. easier spin).

RFJ

UStik - the output arm of a Transmite moved through an arc of about 40 degrees which gave a (near) linear movement of +/- 5/16"

Ray

UStik

Thanks!

pimmnz

And your assessment of the handling pretty much mirrors the real one, at close to Ed's weight and power. My T/F plan Taurus weighs 5.5 lb and uses an LA.46. The ailerons are precise, both in terms of roll rate vs applied amount and in the very good damping, ie the roll stops immediately the ailerons are centered. Pitch control is soft, but, given the size of the elevators, very powerful. It will, under power almost loop in its own length. Unfortunately the spin is, as you have found out, a bit of a hit and miss affair. When it spins, the spin rate is quite quick, with the nose well down, and stops immediately when any of the controls, (you need elevator, rudder and aileron to initiate and maintain the spin) is centered. Rudder is the least effective of the controls, it will slip, and given full rudder at the right time, a good stall turn can be done, but you need a bit of slipstream to make it work properly. Of course, there was not a lot of 'rudder' maneuvers in the pattern back then either. You might have to work on the landing too, cause as the thing is really difficult to stall, and you can only spin it with a bit of power on, you can't actually get the thing too nose high on approach and landing, A bit too much power and it keeps flying, idle right down and as it slows the elevator will run out of authority, before it touches the ground. It takes a bit of practise to figure out that it isn't seeming to hover, with the nose way up, then you are probably flying too fast to land it. Of course, as soon as the nosewheel touches it just sticks to the ground, as intended for the 'Touch and Go'. Once the programme is sorted you will be able to do the full pattern, within the confines of a normal landing strip. The thing is almost '3D' in standard trim. Of course, at 7lb with a .60, all bets are off.
Evan.

UStik

Nice!

Actually, I aimed to reproduce the "reeds experience" and tried spinning without ailerons. This configuration is a borderline case so any small modification may make a difference. In any case I found it helps to use the trick that makes even a C172 spin: slow down maintaining level flight and when approaching stall (or here: full elevator) apply full rudder. Works and is even needed for the simulated Taurus to get spinning without ailerons.

No problem with landing, but I think I know what you mean. With the 40 degrees kick-up elevator the plane approaches butt-down and settles softly. Due to the slender wing, it flares better than e.g. the Kwik-Fli but still lands short. Ed's landing procedure is possible, a bit up trim and power gives a nose-up attitude and low sink rate, it just plops down and sticks to the runway, needing quite a bit of it.

Not tried the rudder maneuvers, but I think the simulator doesn't render the rake. []

pimmnz

Dunno if the rake on the rudder actually makes much difference, at the low speed required to stall, the rudder is probably almost unresponsive, so at the point of spin entry (You have to stall before you can spin) the slow speed isn't going to make the rake important. At high speed with full rudder quickly applied there is a little tail down 'kick' before the roll and pitch occur, but really it is difficult to detect any other effect at any other speed. You can simply ignore anything other than the yaw, so far as the sim programme is concerned. Certainly, so far as I can tell, the supposed 'benefits' of the rudder sweep are practically undetectable.
Evan.

UStik

Glad to hear that, just my sentiments! I always thought the rake was a rave of the time and the simulator programmer rightly neglected it.

As to spinning, I meant you have to slow down just near stall so the yaw induced by full rudder lets the "inner" wing stall and the "outer" wing not. If you stall first, both wings stall but not at their tips and no autorotation occurs. Of course you know this trick, but I wanted to say that the simulator stunningly renders it. At least I'm still stunned because I imagine this effect being there in the simulator.

By the way, not only the blunt-nose airfoil makes Taurus hard to spin. Also the wing planform is not that tapered as seen on modern models to let the stall begin more outboards to the wing tips. Compare the elliptical lift distribution drawn over the trailing edge of the right wing. In the fuselage, red point is neutral point and green point is c/g, shown in the forward 4.75" position giving about 15% static margin. Rearward 5" c/g gives about 13% static margin. Tail area is 25% of wing area, another nice round number (and rule of thumb).

pimmnz

As you say, if you stall first, assuming everything is square, you don't necessarily spin, but, and I believe even back then, if you fly an aerobatic competition which includes a spin, if you do not first stall, then spin, you get a 'zero' for the maneuver. The judges watch for the 'break' then for the rotation, and they count the turns etc. In other words, the controls are at centre at the point of stall, and are at the extreme after the nose drops. If the model is 'wingovered' into the spin, you get nothing. So the Taurus problem is the first bit, you have to stall it straight ahead, then bang everything into the corner to set up the autorotation. Get it wrong and you get a spiral dive, zero points. I find that a bit of power at the stall so that the elevator has a bit more 'bite' helps, then back to idle as you slam the sticks into the corner. Still, the succe4ss rate is only about 50%. Funnily enough the Orion is remarkably good at this trick, and will spin and stop on request. This gives me another recollection, the Orion will also 'flick', the Taurus will not. Something else to feed into the mix...
Evan.

UStik

Again stunning, I can copy that! A bit power helps to stall first, and yet another method is just holding full up elevator (kick-up) and waiting till the model decides to bank on its own (to the left due to torque) and then slamming the rudder stick to the left (I'm still doing without ailerons). But the "trick" just does not mean the model is wingovered into the spin, it only means you see no stall buffeting. Lowering the nose and starting the yaw happen at the same time. Regardless of method, I get no buffeting and not even that nose dropping in the simulator at all.

The propwash seems to be essential for spinning. If it's reduced the model doesn't spin anymore - too less elevator and rudder effect. Likely, Ed knew that and right from the start provided the pusher with a better stalling wing (though even thicker, it had a sharper nose). After all he built the pusher to avoid the propwash. And of course he chose a symmetric airfoil to avoid an airfoil pitching moment which is stall-obstructive as well.

Indeed the Orion is another thing to feed into the mix, other than the T2, the Japan T2, the Flop and the Simla. It's the best-known model next to the Taurus. At least we have the MAN article/plan for the Orion with all of Ed's considerations for its design (like for the Taurus). And seems to me Ed was completely candid about all details and didn't conceal anything. There are no hidden secrets of the contest pilot. Makes him really likeable.

kingaltair

My Feedback: (4)

What about the Taurus-2 with the Bosch(sp) airfoil. The wing is 1" more forward than the others, (making 1" longer tail moment, and the longest of all the Taurus versions)? Do you have that one in that simulator? Do you need measurements, since I now have the plane home wth me.

It would be interesting to see how it vaies with the longer movement and altered airfoil....should spin better.

Picture this photo, (only up in the air).

Duane

UStik

Yeah, that's the next one! But it's a long way to ... have it as a visible rendering and to see it in the simulator. But the flight behavior is more interesting, anyway. We have the wing dimensions and airfoil, I have the two measuring photos for the fuse and tail dimensions, if you have no corrections I can do the flight characteristics. Now I am where I wanted to be: figuring Ed out.

kingaltair

My Feedback: (4)

I already pointed out one figure...the height at the leading edge. I'll try to get some final figures ASAP, but can't guarantee it will be in a day or so.

Duane

UStik

Not much time here as well. Soon is Easter and we're awaiting the maiden flight of the Wester Taurus, that's more interesting for now.

I don't remember the figure, but I think I figured the dimensions out, anyway. The exact fuselage dimensions aren't important, either, except the tail moment arm. I think it's exactly 1.5" longer, the missing 1/4" due to differences in wing saddle. The stab leading edge is 1/4" more forward, slightly enlarging the area. Fin/rudder tips are 1"/1" instead of 1.25"/1.75", fin root leading edge is 0.75" forward, lowering the vertical's aerodynamic center. The fuse nose is shortened by 1.25", the thrust line 0.5" lower and the wing 1" higher. That's why the fuse is nearly 1" flatter at the trailing edge.

The rest is the same, more than you might think. Compare the drawings with the Windows Viewer and it seems the T2 is basically the same layout as the T1, only adapted to the swept wing. Maybe the fuse is that flat because it was made for the very thick carrier wing. The unfinished fuse could be meant as a T2 kit prototype, the wing simply being 1" more aft and the fuse having the "normal" height and vertical moments for the "normal" airfoil thickness. But that's again speculation...

UStik

Oh well, couldn't wait, T2 flies virtually.

As you may expect, it spins very well and even snaps/flicks like crazy! In fact, you can stall it in level flight and it will bank and try to spin, so be careful. I set elevator throw to 30 degrees (25 is enough) instead of the 40 degrees kick-up (is no longer needed because T2 was proportional). It's not vicious though, just stay one mistake high when coming near stall, should be enough to pull out safely. I can't guarantee for the realism of the virtual model, but it surely shows general behavior.

I'm sure because the better spinning doesn't come from the airfoil, at least not directly. The airfoil's stall behavior is not very different from that of the NACA 2419. The wing planform isn't that spin-promoting, either, even though the point of first stall is a bit more outboards. If the model is set up with the very stable 15% static margin (forward c/g) like the T1, it is just as reluctant to spin as the T1.

If it is set to 6% static margin, though, which is still a bit stable, it will spin and snap gracefully. Besides, it's dead "neutral", meaning trimmed for level flight both upright and inverted. OK, only with a small shim under the wing trailing edge to get a bit positive incidence (a trick described by Ed in one of the articles). Of course, snapping is good due to the strong ST 58 engine as well.

The small static margin and neutral behavior is possible because there is no airfoil pitching moment. The elevator is more effective as well. The wing is a bit sleeker than the T1 wing and you have to plan your landing approach to bleed off the speed. The ST 58 will not pull "faster" because rpm and propeller are the same, but it pulls much more (0.94 thrust/weight, 6 lb overall weight) than the Veco 45.

T2 is a much more modern model than T1, neutral, smooth and powerful, predictable, soft landings. Still terrible couplings, much belly pitch and positive roll. Not vicious, just be careful with stalling maneuvers. Don't be scared, c/g is 8.5" behind center leading edge on the virtual model. Again, no guarantee, but expect a great flier!

P.S.: You can start with the c/g 3" more forward (or even more), the model is still under control, just with substantial elevator. Then gradually approach the right c/g position. Just in case you intend to fly the T2 at Easter.

UStik

double post deleted

pimmnz

Looks like Ed was on the right path for the modern propo model, would have been interesting to see where the Taurus development would have ended up. One thing you can say, development of the ideas was pretty rapid, I don't see that sort of concentrated change (Astro-hog, Orion, Taurus) in such a short time happening these days. Have to say the modern Pattern or IMAC models all look pretty much the same, to me anyway. I like models with character.
Evan.

cygnet

My Feedback: (33)

Lots of talk about the spin I flew a Taurus for many years in competition and never had a problem with the spin or the snap, as a matter of fact you have to be careful when doing snaps the stab has very little gluing area and I blew the tail right off mine, you had to see what happen next, the whole tail was hanging on by the rudder clevis, the old Taurus just weather viened and I cut the power and she came down like a heilcopter, put the tail back on that night and was flying the next day, unreal plane. If it won't spin move the CG back until it does, one other thing with the CG back a little it will land just about hands off, if you are brave enough it will land hands off but thats another story.