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Author Topic: P30 D/T  (Read 3624 times)
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betocastrucci
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« on: November 12, 2013, 04:36:03 PM »

Last Sunday lost another Saturno P30, this time launched by my son Luiz in a local contest, luck that it's gone after the last flight (Luiz gotta 3rd). The dt stuff (viscous timer on estab) worked well, the model did a loop, but wasn't effective, the model was still climbing after several minutes.
Our group have lost many models at the same field, with the same problem: dted, but still flying.
I'm finishing another duo of Saturnos, and this time I intend to use wing dt. What system is the most effective with viscous timer?
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DaddyO
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« Reply #1 on: November 12, 2013, 05:33:10 PM »

Sorry to hear of Luiz' lost model.

Just working on a new P30 myself and I intend to use the same DT as I did on my CO2 ships which seems pretty effective. I think there are details on my CO2 build thread)  The DT is mounted amidships (I use a fuse) and the wing and tail both operate from the same DT. (wing leading edge upwards and tail trailing edge upwards) You can use either one or both and by varying the angles you can alter the nose down attitude.

I also understand that a pop OFF wing works very effectively, but I've not tried one myself. (Wing is attached to the rear of the fuse on a swivel and the model helicopters down under it)

Hope these ideas help
Paul
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Tmat
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« Reply #2 on: November 12, 2013, 05:40:00 PM »

Beto,
The most effective DT for a P30, that will always bring the model down is to DT the wing off of the airplane, and have it attached to the wing tip and the back of the fuselage with monofilament line. The fuselage points down and the wing streams behind it spinning to slow the descent. The monofilament must be attached to the fuselage with a swivel type fishing device so that the spinning wing will not twist the monofilament.
I'm sure that others here can show details of how such a mechanism can be actuated from a viscous timer.

Tony
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applehoney
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« Reply #3 on: November 12, 2013, 06:33:35 PM »

Total agreement with Tony.  I use a drop-off wing on my Saturno and it's 100% effective
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Dave Andreski
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« Reply #4 on: November 12, 2013, 07:20:02 PM »

Beto,
Does this help?
Dave
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craig h
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« Reply #5 on: November 12, 2013, 09:29:39 PM »

I have always used wing d/t with just the trailing edge pop up..and the use of fuse...it came down everytime..some don't like this for it comes down in
 a spiral nose first..and was usually found upside down on it's back on the ground...but I never lost a plane and never had a broken prop nor wing.

    Craig h
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Tmat
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« Reply #6 on: November 12, 2013, 11:31:16 PM »

I use a very similar method that Dave showed on my Pirate P30 (see the attached photo) only I used a band burner E-timer instead of a viscous timer. Works every time and has never failed to bring the model down.
As in the sketch Dave supplied, the DT hold down line runs through a plastic straw inside the pylon and around a wire turn around behind the pylon before coming forward to the timer. FYI, parts were supplied by Starlink.
I used Spiderwire for the DT line, which is a non stretch Spectra based fishing line. The turnaround is very important if you use a Viscous timer as it is needed to take some of the load off of the timer.


Tmat
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Rewinged
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« Reply #7 on: November 13, 2013, 12:51:22 AM »

Since it appears the Saturno uses PGI trim and doesn't have a pylon, you might look at what I did for the TitanK.  See this post for pictures; the DT is shown reasonably well:
http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=861.msg119117#msg119117

This is a pop-off wing approach that puts all the bits forward of the CG.

The line from the viscous timer goes over a lever/force multiplier.  The wing tie-down is rubber over the rear of the wing, tied to 30-lb Spectra, over the LE and under a portion of the wing LE platform, and then to the other end of the lever/force multiplier.  The lever/force multipler is just a piece of music wire through an aluminum tube.

This has worked very well.  I'm going to change the bends in the force multiplier a bit to make sure the line from the timer doesn't slip off when I'm fiddling with things, but that is the only change I think I need.

You can also see my wing tether from the right wingtip, over the stab, to the fuselage.

Regards,
Bill
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Tapio Linkosalo
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« Reply #8 on: November 13, 2013, 02:19:04 AM »

The pop-off-wing -DT is probably a good solution for pampa, but in Finland it is a killer: most high flights see a considerable risk of landing in the woods, and if the model does, the line that connects the fuselage and wing hanging around the branch is really hard to get out if the tree. Don't ask me how I know.

A friend of mine has a model where the center joiner of the wing pivots so that the wings turn tip-to-tip. To slow down too fast descent, he also pops the tail up some. The DT is funny to look, the model looks like a goose that has been shot, with wings folded it really falls off the sky....

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Dave Andreski
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« Reply #9 on: November 13, 2013, 04:19:22 PM »

the line that connects the fuselage and wing hanging around the branch is really hard to get out of the tree. Don't ask me how I know.

I agree. It's happened to me.
Dave
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applehoney
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« Reply #10 on: November 13, 2013, 04:43:32 PM »

I remember that well.   That tree's a model magnet
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Dave Andreski
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« Reply #11 on: November 13, 2013, 04:59:32 PM »

I remember that well.   That tree's a model magnet

Jim,
I actually miss that tree! I need to get there more often.
Thanks to you and Bob Morris my Rodger Dodger only suffered minimal damage where the tether line attached to the rear of the fuselage.
Outcome would have been different had I used Kevlar or some other super strong synthetic line. Bob's razor blade rig worked well on my Coats and Clark 'button thread'.
Dave
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betocastrucci
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« Reply #12 on: November 14, 2013, 04:31:33 PM »

Got a Saturno V3 and changed dt systems from stab to wing. Use the same viscous timer with long 1/16" SS rubber, that goes to the motor peg and back to leading edge of wing. Trailing edge with rubber rings. Let´s try the new system.

http://lh4.googleusercontent.com/-Q8NpGZ5nxgw/UoU7Lh9-_LI/AAAAAAAABCM/PpyRTXZ8imQ/w782-h576-no/satv3_17.jpg

http://lh6.googleusercontent.com/-lCIglXq7Sng/UoU7Nel9sHI/AAAAAAAABCc/nZQ9QoDrB80/w973-h576-no/satv3_18.JPG

http://lh5.googleusercontent.com/-NgjFR52FJlY/UoU7NCLotFI/AAAAAAAABCY/VlzaDbXVrBU/w826-h576-no/satv3_19.jpg
P30 D/T
P30 D/T
P30 D/T
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atesus
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« Reply #13 on: November 14, 2013, 05:56:33 PM »

I was under the impression that the tilt-up wing DT would essentially be the same thing as the tilt-up stab however after installing the DT on the wing on my Veron Sentinel, I can say that tilt-up wing is significantly more effective than tilt-up stab for the same tilt angle. I believe the main difference is that with tilt-up wing, once the wing tilts up the plane also experiences a CG shift and becomes nose heavy thus even less flyable. Not so with the tilt-up stab.
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Tapio Linkosalo
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« Reply #14 on: November 15, 2013, 02:24:20 AM »

Ah-ha. Good point. I have seen friends' tilt-up wind model descend real fast, but never got to think why it would be more efficient way to DT. Your explanation makes sense.

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Hepcat
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« Reply #15 on: November 15, 2013, 07:19:19 AM »

Atesus (reply #13).

I am not wanting to be 'picky' because substantially I agree with everything you say but isn't it not that the CG moves forwards but that the centre of lift moves a long way back?

John
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craig h
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« Reply #16 on: November 15, 2013, 07:33:22 AM »

 Since I use the tilting of the leading edge of my P-30's to d/t...my simple thought is: by breaking the linear flow of the wing it casues the wing not to have
 lift...thus the plane will not fly! I may be wrong..I try to keep things simple.. Smiley

   Craig h
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Tapio Linkosalo
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« Reply #17 on: November 15, 2013, 08:23:10 AM »

John is of course right: tipping the tail moves the CG forward (ever so slightly), while tipping the wing actually moves it aft! :-)

Having a second thought, could it be that the difference is all about the fuselage drag? If you consider conventional DT (on models that do not spiral, like F1B), the tailplane angle affects things a lot, and in general it seems that at 45 degrees the model shows more horizontal movement than at higher tail angles. It seems to me that during DT the tail is actually still flying, pushing the model forward (the faster the lower the DT angle). Therefore, with tip wing DT, the model is coming down with fuselage pointing the direction of the airflow = less drag = faster descent?

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Bargle
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« Reply #18 on: November 15, 2013, 05:10:33 PM »

I found this type of viscous timer in a club newsletter and wondered if anyone had any experience with it?
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Dave Andreski
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« Reply #19 on: November 15, 2013, 05:43:07 PM »

Bargle,
I first saw this on the old 'Windy Sock' site over ten years ago and wondered why they didn't include an example of how it's rigged on any particular model.
Looks simple at first but arriving at the correct size of silly putty pellet is frought with difficulties.
Here's the text that went with the pic.
Dave
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Bargle
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« Reply #20 on: November 15, 2013, 09:12:38 PM »

Thanks, Dave. I was kinda wondering about the pellet size thing myself. The newsletter I saw it in wasn't the Windy Sock one. It just had the illustration. I think I could come up with a linkage setup, but I wondered how consistent it would be.
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frash
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« Reply #21 on: November 15, 2013, 10:36:11 PM »

Sometime about 1970-1972 I used the Type Cleaner Pellet DT on either a Bob Stalick 0.020-powered Mini-Rod and/or a Dave Lindstrum 0.020-powered PayLater. This DT worked sometimes, but one of these planes flew away, probably the Mini-Rod and most likely due to DT failure by a novice modeler.

http://www.airplanesandrockets.com/airplanes/mini-rod-article-plans-feb-1969-aam.htm

Fred Rash
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atesus
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« Reply #22 on: November 16, 2013, 04:43:40 AM »

John, Tapio, I may have inadvertently oversimplified things in my mind, it comes naturally with lack of knowledge Grin.

John, did you mean to say that the CG moves "back" but the CL moves even further back (both with respect to their non-tipped position)? If that's the case, I think I see how this is happening. This is so because the mass of the wing shifting backwards due to the tilt is only one of the constituents in the overall CG whereas since CL is solely defined by the wing (is it so?), so its shifts back directly in proportion with the apparent movement of the wing.  Or is this all non-sense I'm saying?
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Tapio Linkosalo
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« Reply #23 on: November 19, 2013, 07:34:15 AM »

Quote from: Tapio Linkosalo
Having a second thought, could it be that the difference is all about the fuselage drag? If you consider conventional DT (on models that do not spiral, like F1B), the tailplane angle affects things a lot, and in general it seems that at 45 degrees the model shows more horizontal movement than at higher tail angles. It seems to me that during DT the tail is actually still flying, pushing the model forward (the faster the lower the DT angle). Therefore, with tip wing DT, the model is coming down with fuselage pointing the direction of the airflow = less drag = faster descent?

Carrying on the train of thought, pop-off wing is said to be efficient. The wing comes along behind the fuselage more or less edge-on, so that cross section is less than with tip-up wing, but on the other hand the wing also tumbles, which probably adds a lot of drag. So again, maybe the fuselage is a major contributor for drag, and therefore tip-up-wing an efficient way to get light models out of lift?


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applehoney
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« Reply #24 on: November 19, 2013, 03:20:39 PM »

As a flyer of P30's for many years I have used tip-tail, tip-wing, drop-off stab and drop-off wing d/t systems.     I am confident that the drop-wing is by far the most effective, followed by the drop-off stab.   

The tip stab is least effective of all, slow descent and readily overcome by thermal activity; the tipping wing a little better but still prone to loss .. better on heavier models around Senator size.
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