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Ed Kazmirski's Taurus

Old 04-07-2009, 03:03 AM
  #1201  
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Default RE: Ed Kazmurski's Taurus

Interesting, Cygnet, but what did yours weigh, and what was pulling it along? We're talking here about a 5.5lb airplane with an old .45 up front, and no matter where you put the cg, it ain't easy to stall. Speaking of which, I have started making a 'kit of bits' for my 'PCM' Taurus, and I can only find a couple of unemployed engines, a K&B series 73 .40 (with Perry carb!) NIB, and an OS .40 RC (the old baffle piston engine) also NIB. The OS comes with its own little muffler, but the K&B still has the exhaust baffle holes in the side exhaust stack, and will likely need a Macs or similar muffler. I need to redraw the bearers to fit one of these engines, but which one? What say you, chaps?
Evan.
Old 04-07-2009, 07:01 AM
  #1202  
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Default RE: Ed Kazmurski's Taurus

Yeah thanks cygnet, very interesting, and are you an old-school spinner/snapper or did you cheat with ailerons?

Did you shim the wing to a new incidence angle when moving the c/g back?


Evan, if it's the OS [link=http://www.osengines.com/history/ostimeline04.html]H40P[/link] I'd vote for it.
Old 04-07-2009, 07:35 AM
  #1203  
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Default RE: Ed Kazmurski's Taurus


ORIGINAL: 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.

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 inted to fly the T2 at Easter.
Thanks Burkhard...you're bringing a new perspective to this thread with your simulations. Thanks for the "heads-up" about how the plane SHOULD FLY.

I would think the airfoil changes would be significant, and that was the motivating factor behind the switch to the Bosch airfoil and tapered wing...to correct for the high degree of stability, and lack of a good spin. The less blunt leading edge with the widest point of the airfoil further back would help the plane to spin, along with the taper nature of the wing.....but I am not that knowledgable about aerodynamics, so I defer to others with more knowledge.

One of the questions I still have is just where to put the C/G. The "Japanese" Taurus-2 had its C/G 6-3/4" back according to the text by the pictures.

Duane
Old 04-07-2009, 08:21 AM
  #1204  
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Default RE: Ed Kazmurski's Taurus

ORIGINAL: kingaltair
One of the questions I still have is just where to put the C/G. The "Japanese" Taurus-2 had its C/G 6-3/4" back according to the text by the pictures.
Well, as I wrote last but not least in #1197, I would say c/g is right at 8.5" behind center leading edge. You can start 3" more forward (or even more), the model is still under control, just with substantial elevator. Then gradually approach the right c/g position. But you have the landing gear as a clue. 1" in front of the wheel axles could be a good c/g position as well. Just in case you intend to fly the T2 at Easter.

I believe the Japan T2 was one of Ed's first attempts in swept wings. As measured in an earlier post, it was a standard TF fuselage, only the wing built with straight trailing edge. So the c/g had to be 2" more aft and the tail moment arm was effectively shorter by that amount. Still the wing had the NACA 2419 airfoil and the plane had the big stability margin. That means it must have been a dog to spin.

Next attempt was the even thicker carrier wing, but with a special fuselage which reconstituted the tail and nose moment arms of the straight wing contest (Nats/VRCS) Taurus. That's your T2 fuse. Due to the very thick wing, Ed reduced the vertical moment arms (wing higher, thrust line and empennage lower). Maybe it didn't spin well either due to the very thick and blunt wing.

Then he had also the pusher and obviously planned to use its wing on a T2. Maybe therefore he built the unfinished fuse with the old vertical moment arms because this wing is "normally" thick, and only 1" longer tail / shorter nose moment arm because it was planned for proportional and he believed that needed shorter tail moment. For some reason, he gave up and simply used the carrier fuse which was built earlier with long tail moment for reeds.
Old 04-07-2009, 09:29 AM
  #1205  
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Default RE: Ed Kazmurski's Taurus

ORIGINAL: UStik

I believe the Japan T2 was one of Ed's first attempts in swept wings. As measured in an earlier post, it was a standard TF fuselage, only the wing built with straight trailing edge. So the c/g had to be 2" more aft and the tail moment arm was effectively shorter by that amount. Still the wing had the NACA 2419 airfoil and the plane had the big stability margin. That means it must have been a dog to spin.

Next attempt was the even thicker carrier wing, but with a special fuselage which reconstituted the tail and nose moment arms of the straight wing contest (Nats/VRCS) Taurus. That's your T2 fuse. Due to the very thick wing, Ed reduced the vertical moment arms (wing higher, thrust line and empennage lower). Maybe it didn't spin well either due to the very thick and blunt wing.
Wait just a minute; I think we need to get the time line correct:

1) The Taurus-2 fuselage was (regardless of whether it's oldest or not) was definitely in its present state by the summer of 1963. Remember the dated "Carrier photos" say Aug 1963.
2) It originally had the thick, (Carrier) wing, which was Ed's back-up for the '63 W/C
3) The Japanese T-2 came along later in the early months of 1964. It was testing Ed's theories on a shorter tail moment, (2"shorter), and more dihedral.
4) The second T-2 wing came next. I don't know if the "pusher" was first or the modified Taurus-2, (that accepts the thinner wing). This wing HAD to have built AFTER the 1963 W/C since Ed got the airfoil from Bosch. I would say the T-2 striped wing came about early in 1964.

Duane
Old 04-07-2009, 02:00 PM
  #1206  
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Default RE: Ed Kazmurski's Taurus

ORIGINAL: kingaltair
3) The Japanese T-2 came along later in the early months of 1964. It was testing Ed's theories on a shorter tail moment, (2"shorter), and more dihedral.
Maybe, but wasn't important for me. I considered what the unfinished fuselage could be built for. I don't doubt the dates, and maybe the Japan T2 was for testing the winter 1963/1964 theories, as mentioned in the Grid Leaks Monitor. The pusher was a project in this winter. But anyhow, the unfinished fuse is made for the pusher wing and has neither the very long tail of your T2 nor the very short Japan tail. In fact, it reconstitutes the proven moment arms of the contest T1 (as well as the dihedral), just for swept wing. So both carrier T2 and Japan T2 were errors in Ed's trial and error sequence.
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Old 04-07-2009, 02:18 PM
  #1207  
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Default RE: Ed Kazmurski's Taurus

Maybe, but wasn't important for me. I considered what the unfinished fuselage could be built for. I don't doubt the dates, and maybe the Japan T2 was for testing the winter 1963/1964 theories, as mentioned in the Grid Leaks Monitor. The pusher was a project in this winter. But anyhow, the unfinished wing is made for the pusher wing and has neither the very long tail of your T2 nor the very short Japan tail. In fact, it reconstitutes the proven moment arms of the contest T1 (as well as the dihedral). So both carrier T2 and Japan T2 were errors in Ed's trial and error sequence.
I feel the time line is important for all of us , just to keep the sequence straight.

I think I know what you mean, but I would not call the Carrier Taurus-2 an "error", because the fuselage went on to be part of the final Taurus in the evolutionary line. Even the Japanese T-2 could be considered partially successful because it looks like the same wing as the final T-2 was part of that variant. They were both "partial successes".

I consider the Taurus-2 in the auction that he flew during the 1964 season to be the most successful plane in the series from a flying standpoint. It was the last in the line, (I am not counting the Simla here as it is a whole different project due to the size difference).

The Taurus-2 in the crate was the final Taurus.

Duane
Old 04-07-2009, 04:52 PM
  #1208  
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Default RE: Ed Kazmurski's Taurus

Ustik, the instructions call it Max-40 R/C, I believe the H40P was the racing (P=pylon) engine. I am already running one of these old 40 R/C's in a 362 delta where it works very well and this one was to be my 'spares' engine (You can't get the bits any more, you know). I still don't know which to use, but as the bearer spacing is very similar I can continue cutting bits and decide later. The same mounting hole spacing would be too much of a coincidence to expect, so it might end up with the engine I can find spares for.
Evan.
Old 04-07-2009, 05:35 PM
  #1209  
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Default RE: Ed Kazmurski's Taurus

Duane, if I read you correctly, does this mean that Cees has built a model of the Last Taurus, not the First?

On a slightly different tack, does anyone know when the 'crate' piccie was taken? I haven't got that article, and I'm too lazy to try and find it. Just thinking that if it was taken specially for the article, it could have been taken after the adventure, in Ed's back yard, possibly with the PCM removed and the new T2 in place in preparation for the next W.Champs. Just a thought...
Evan.
Old 04-07-2009, 09:06 PM
  #1210  
cygnet
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Default RE: Ed Kazmurski's Taurus

Mine was 6lbs and had a Gold cup 61 in it. The CG was just ahead of the landing gear block if you pushed the tail down it would stay down.
Old 04-07-2009, 09:16 PM
  #1211  
cygnet
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Default RE: Ed Kazmurski's Taurus

I always entered the sping with just the elevator and rudder but you could tighten up the spin with the ailerons, as for shimming up the wing no just left it stock. The only time that spinning was really hard was in wind it would just want to keep flying but in calm conditions just slow it down and pull back on the elevator the left wing would always drop first then kick the rudder I used dual rates on rudder so the spin was on high rate I used low rate for all rolling manouvers, the snap was done on low rate rudder also if I used high rate the tail would get to deep and it was ugly.
Old 04-07-2009, 10:31 PM
  #1212  
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Default RE: Ed Kazmurski's Taurus

OK Cygnet, mine is 1/2 lb lighter with a .46 in it. As I said, it won't spin without aileron as well, and even then only about 50% of the time, regardless of the wind (which shouldn't make any diff any way). Obviously the lighter loading and smaller engine are not helping the situation. Oh well, back to Perigee for that sort of stuff.
Evan.
Old 04-08-2009, 03:30 AM
  #1213  
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Default RE: Ed Kazmurski's Taurus

Thanks again cygnet, that cleared it up entirely! As Evan said, it has to do with weight, and a powerful engine even adds to the snap-ability (nice word). But crucial ist c/g position. Following your specifications, I took the virtual Top Flite Taurus and set the c/g 1" back. The static margin is only 3.5% now, what I get as well when I balance a later pattern model, e.g. Kwik-Fli, for neutral behavior. Taurus would require negative wing incidence in addition to become neutral. Anyway, the standard static margin is even 15%, just to show why it's crucial. Engine power was left unchanged.

Now I can copy the (even very) good spinning and snapping in the simulator. By contrast, the stock Top Flite Taurus at 5.5 lb weight barely spins, and the 1" longer "contest" Taurus at 5.25 lb weight barely spins as well. And yes, the model is now balanced for slow flight and will grease in for landing. You can control the approach with power, without elevator.


Duane, I have to apologize, I was wrong about the Japan T2 (should have waited till I had it simulated). It flies noticeably better than the stock TF Taurus. Maybe it was intended to show a simple means how everybody could be up to the mark in early 1964 (dawning proportional times): Take a stock TF kit, build the wing with straight trailing edge and 3.25" dihedral instead of 2.25" (5.0/3.3 degrees), and set the c/g back by 2" to 6.75". As it turns out in the simulator, that gives a nicely balanced model, still quite stable but spinning and snapping even easily (due to "only" 10% static margin).

Top views of the 1" longer "contest" Taurus 1 (auction 1) and the "contest" Taurus 2 (auction 2) for comparison. Size your browser window to show 4 (thumbnail) pictures in a row.
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Old 04-08-2009, 04:38 AM
  #1214  
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Default RE: Ed Kazmurski's Taurus

No Evan, nice idea but I think can't be because the vertical tails are different. Compare the picture of the carrier T2 and Cees' picture. The carrier / existing T2 has the same rudder hinge line rake as the standard Taurus, just the vertical tail outline is different. On Cees' model, it's the other way around, same outline as standard but more rake.

The Africa article was not posted entirely, I think Ray posted the picture and the first page (#298 p12, #341 p18). I pondered about the shadow print in the crate picture. It seems to show a rather high solar altitude. End of April was nearer to mid-summer in Chicago than in Africa, but I really don't know. Anyway, I think the picture was shot immediately before or after a journey to document the secure crate packing and the intact condition of the models. I'd say the journey to Africa for the reason given above, and I'd guess after the journey due to traces of use on the crate.

Still only Cees has the hi-res scan of the original picture, I think he got it from Chuck.
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Old 04-08-2009, 06:05 AM
  #1215  
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Default RE: Ed Kazmurski's Taurus

Thanks UStik. I see the date of publication as December 1962, so the piccie could have been taken at any time up to November 1962, the trip being in May. Gives Ed a bit of time to put almost anything in there. I know, I'm just playing devils advocate here, but much has been made of the contents of the crate, and yet we still ain't sure when the photo was taken, or where. I still believe that Ed's first two recognisable Taurus were in the box when he went to Africa, but that does not mean that the photo shows those two models, for the reasons given. I seem to remember that the right hand model, on the high-res image, showed a dark marking on the r/h side of the fin that just might have been the bunny on the MAN cover model, which then only leaves the identification of the left hand fuselage. If by some magical computer trickery you could compare the lengths of the two and the L/H one is shorter, then you would have to say that it was the prototype Taurus, as there isn't enough side view of either to compare the fuselage heights. Anyway, enough of this stuff, I need to get on with part cutting and get an original Taurus under way. It will be an interesting exercise to be able to fly the models 'back to back' for comparison and see if your computer predictions match the reality.
Evan.
Old 04-08-2009, 07:19 AM
  #1216  
kingaltair
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Default RE: Ed Kazmurski's Taurus

ORIGINAL: pimmnz

From Evan: I see the date of publication as December 1962, so the piccie could have been taken at any time up to November 1962, the trip being in May. Gives Ed a bit of time to put almost anything in there. I know, I'm just playing devils advocate here, but much has been made of the contents of the crate, and yet we still ain't sure when the photo was taken, or where. I still believe that Ed's first two recognisable Taurus were in the box when he went to Africa, but that does not mean that the photo shows those two models, for the reasons given. I seem to remember that the right hand model, on the high-res image, showed a dark marking on the r/h side of the fin that just might have been the bunny on the MAN cover model, which then only leaves the identification of the left hand fuselage. If by some magical computer trickery you could compare the lengths of the two and the L/H one is shorter, then you would have to say that it was the prototype Taurus...

From UStik: ....I was wrong about the Japan T2 (should have waited till I had it simulated). It flies noticeably better than the stock TF Taurus. Maybe it was intended to show a simple means how everybody could be up to the mark in early 1964 (dawning proportional times)....
We have no way to be sure exactly when a lot of the details happened. You can't measure "history", it unfolds, and can't be repeated. To reconstruct history you need to look at the overall evidence, (including articles and testimony of eyewitnesses, which now are few). I think what we have to do is look at the most LIKELY time sequence rather than something more unlikely. For that reason, I would assume the crate picture in the article to have been taken sometime during the trip rather than later. The photographer was with them on the trip. Ed had a very busy year in 1962, and not a lot of time for building alternative models, plus there is a minimum of two months, and most likely 3-4 months from when an article is submitted, to when it's published; therefore I feel the safest assumption is the picture was taken just before, during, or immediately after the trip to Africa.

About the Playboy bunny, we have a picture showing the right side of the fin of the Taurus during the 1962 NATS, and there is NO BUNNY; it must have been added between the NATS and the cover photo shoot for the Jan 1963 MAN issue.

About the Japanese Taurus-2. The ONLY time we see it is during the trip to Japan during the cooler months of late 1963 or early 1964. We also know Ed converted the original configuration of the Taurus-2 with the thick wing to the second striped wing, and he used that combination for the 1964 season, and afterward. I wish I could pinpoint exactly when the photo taken by my Dad was shot, but I believe it was 1965...maybe even 1966. At any rate, it was the FINAL configuration of the Taurus-2. Now the question...why didn't Ed stay with the shorter tail moment/increased dihedral version of the Taurus-2 we see in Japan; there must have been a reason for Ed to go to the trouble of switching back, (converting to) the much longer tail moment version using the converted T-2 fuselage. In the end, he must have preferred the longer tail moment over the shorter Japanese T-2.

Duane
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Old 04-08-2009, 08:13 AM
  #1217  
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Default RE: Ed Kazmurski's Taurus

Well, I wanted to offer an explanation by seeing the Japan T2 as an easy way for normal people to upgrade to T2 standard. In this case/phase that meant swept wing, more dihedral and shorter tail. As you wrote before, Ed soon realized this to be wrong, and even though the Japan T2 flies quite well the final T2 is noticeably better. If Ed had reduced the dihedral further he would have had an even better ship.

A more technical explanation could be the symmetric airfoil. Due to the absence of down pitching moment quite small static stability margins are practicable, and they are desirable for neutral flight behavior. But this in turn might require a longer tail and shorter nose for better damping. (Still have to check that.) It was no trouble to take the carrier fuse and put a few balsa strips on the wing saddles to make the pusher wing fit. And seems Ed completely stopped building after the sad Simla affair.
Old 04-08-2009, 08:48 AM
  #1218  
kingaltair
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Default RE: Ed Kazmurski's Taurus


ORIGINAL: UStik

..... normal people to upgrade to T2 standard. In this case/phase that meant swept wing, more dihedral and shorter tail. As you wrote before, Ed soon realized this to be wrong, and even though the Japan T2 flies quite well the final T2 is noticeably better. If Ed had reduced the dihedral further he would have had an even better ship.

A more technical explanation could be the symmetric airfoil. Due to the absence of down pitching moment quite small static stability margins are practicable, and they are desirable for neutral flight behavior. But this in turn might require a longer tail and shorter nose for better damping.
HUH???[:-]

Define "static stability" and "damping" auf English bitte

Duane
Old 04-08-2009, 09:26 AM
  #1219  
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Default RE: Ed Kazmurski's Taurus

Static stability margin is the ratio of two "moment arms":

distance between the c/g (mass center) and the neutral point (aerodynamic center) of the airplane
divided by
mean wing chord length (in the sketch simplified to root chord)

A big static margin means the plane's weight pitches down heavily so the horizontal stab has to push down heavily as well - very stable setup.

Damping is another cup of tea. Imagine the airplanes tail is wagging, then damping means how soon this oscillation is reduced to zero. Much damping - no oscillation at all but just returning to straight and level.
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Old 04-08-2009, 02:35 PM
  #1220  
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Default RE: Ed Kazmurski's Taurus

Duane, just flew the virtual T2. Maybe the c/g 0.25" more forward to 8.25" feels a bit more solid (it's more stable, 8.5% static margin). Just in case you don't like neutral setup. (But even 3" more forward works, it's the safe side.)

The plane seems to do some tail wagging as it comes out of a stall turn, not much but not nice either. So I tried the tail modifications (the end plates), set 2/3 more vertical tail area and 1/4 less horizontal. It seems to cure this problem, looks smoother.

As to the carrier wing (I have to try), are you sure it has a semi-symmetrical airfoil? Seems 22% thickness correct? Would be 2.75".
Old 04-08-2009, 03:24 PM
  #1221  
kingaltair
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Default RE: Ed Kazmurski's Taurus

ORIGINAL: UStik

Duane, just flew the virtual T2. Maybe the c/g 0.25" more forward to 8.25" feels a bit more solid (it's more stable, 8.5% static margin). Just in case you don't like neutral setup. (But even 3" more forward works, it's the safe side.)

The plane seems to do some tail wagging as it comes out of a stall turn, not much but not nice either. So I tried the tail modifications (the end plates), set 2/3 more vertical tail area and 1/4 less horizontal. It seems to cure this problem, looks smoother.

As to the carrier wing (I have to try), are you sure it has a semi-symmetrical airfoil? Seems 22% thickness correct? Would be 2.75".
This is great, (assuming you can take all these measurements, stick them in a simulator, and it accurately represents the real thing). I'm still a little skeptical that it is exactly like the real plane. I will print out your drawing and test all the measurements heute abend. Do you feel the T-2, (as closely as you can simulate it), flys better of worse compared to the Japanese, (short tail moment) Taurus-2)? Or could it be the PILOT's fault??

I just got back from an SPA judges clinic, designed so we will all judge the maneuvers the same way. The clinic also points out places for improvement when we fly the maneuvers. I had heard a lot of debate in the past about whether a "tail wag" was or wasn't a bad thing. Some people, (like me), don't mind the "wag" if it happens because it indicates without a doubt that the plane was in a truly stalled condition. The wag is not something I am TRYING to achieve, but I like to see the stall either way. The instructor made a point of saying there should be no downgrade if the tail wags some, (at least you know there was no "wingover"). If Jim Kimbro is viewing this message, I'd appreciate his imput on the subject.

The thick wing has a SYMMETRICAL AIRFOIL, but very thick and very blunt, (ie round leading edge). The T-2 (Bosch) airfoil, as you pointed out has its greatest thickness at 37%, so it has a "sharper" leading edge. I'll measure it as well.

Duane

Old 04-08-2009, 04:58 PM
  #1222  
pimmnz
 
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Default RE: Ed Kazmurski's Taurus

Duane, down our way if you get a bit of 'tail wag' it's generally because you got off the rudder a bit too soon, and quick, and you get downgraded for it. They (judges) also like a good vertical after the turn, so generally you have to push a little down and hold just a bit of rudder until the turn is truly completed and the vertical dive properly established, then gently off the rudder so they don't see the tiny slip correction. Takes practise, but gets good points when you get it right. Perhaps if UStik tries this wheeze it might make the thing look better?
As for the crate picture, I did say I was playing devils advocate, I wasn't trying to muddy the waters. My instinct tells me that the fuselages are the first two Ed built, but we must test the theory in the proper manner... I have no idea how long after the '63 W.C Ed kept flying as the press seemed to have lost interest in him, he pops up on the Carrier, then in Japan, but after that, unless it is personal recollection, he seems to have disappeared. I can't think that he just stopped, but after the Simla affair, and the comparative ease of transport of the Taurus vs Simla, it is not so surprising that T2 was used, and it would have been a better flyer than the other versions, so it was, more likely, his 'everyday' model. Again, perhaps a quiz of some of the long serving members of the Chicago club might give a better picture of the last years of Eds active participation in the hobby.
Evan.
Old 04-08-2009, 05:20 PM
  #1223  
UStik
 
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Default RE: Ed Kazmurski's Taurus

It's good to be sceptical, belongs to the engineering mindset. The simulator is not 100% realistic, even though it comes very close if I have all necessary information/data. The airfoil data are always uncertain so I just compare several cases to see which parameters are important.

The contest T2 flies better than the Japan T2, no doubt, and no doubt due to the symmetric airfoil. I'm interested in the 35% airplane influence and not in the 65% pilot influence (sounds better than error), at least for now.

The tail wag was still there after the modification, it was just more damped, meaning there was only one wag instead of oscillations.

Please check the carrier wing airfoil carefully because it is hard to see if a thick airfoil is really symmetrical. If you compare a 2415, 2419, and 2422, the camber is all the same (2%) but it seems less (or even none) the thicker the airfoil is. It's important because it makes all the difference. I just tried a NACA 2422 for the T2 and even if I set the airfoil parameters for a decent stall behavior (what this airfoil really doesn't have) the plane won't stall with normal elevator throw, only with kick-up (as any Taurus with a semi-symmetrical airfoil).

The problem is the 0-0 wing-stab setup Ed chose for the Taurus. Zero incidence is not zero lift for a semi-symmetrical airfoil, so there is some decalage (about 1.5 degrees). This requires the very stable setup (big static margin, forward c/g) and the stab has to work hard against this forward c/g and the airfoil pitching moment. Without kick-up, there's just not enough elevator/stab effect left to accomplish a stall.

Seems this point is the most important. All others are not that influential, like dihedral, sweep, moment arms, and so on. Phil Kraft wrote somewhere that he tried several semi-symmetrical airfoils but was not satisfied with all of them, so he changed to symmetrical airfoils.
Old 04-08-2009, 07:50 PM
  #1224  
pimmnz
 
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Default RE: Ed Kazmurski's Taurus

Yep, the problem with using the standard Taurus in any aerobatic comp is the unpredictability of the spin. In competition the airplane must be able to stall, and 'on command'. Regardless of its other attributes this one failing is what prevents it being the competition aerobatic airplane it could be, or should have been. I did not know, before this thread started, that a symmetric airfoil was developed for it and it seems strange that Ed persisted with the 2400 series wing for so long, Dunham had flown a symmetric airfoil on the Voltswagen, deBolt had started using them, and Ed would have known about it for sure. Oh, well, anothe Taurus mod to be done, I guess.
Evan.
Old 04-08-2009, 11:48 PM
  #1225  
cygnet
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Default RE: Ed Kazmurski's Taurus

I think Ed stayed with the airfoil beacuse of the radio equipment of the day, if you have ever flowen a reed radio you will know what I mean, you want all the stability you can get things move really slow with a reed radio.

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