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Author Topic: Show us your P-30's  (Read 61650 times)
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Tmat
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« Reply #425 on: June 15, 2011, 03:11:28 PM »

What do you plan to use for the DT actuator?

 Have not tried to rubber band burners, but the large current consumption to make the wire glow worries me.
I too am interested in this project Pappy (small timer for clg with beacon/altimeter) and await further details with saliva dripping on the keyboard.... Grin
My opinion is that a timer is unneccessary for clg and a RDT is far more useful. Being able to chose when you DT has proven to be very useful for tip launch gliders and most RDt equipped birds now have no timer, just use a signal from the RDT to actuate the DT (servo or pager motor). The Burley band burner is a very lightweight mechanism that works very well. (see attached photo). Weight is 1.4 grams with battery.
The power consumption of the burning circuit is not that great Tapio because it only requires a few milliseconds (I'm guessing) to heat the wire and burn through the band.

Tony
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Pappy
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« Reply #426 on: June 15, 2011, 07:55:34 PM »

Good Evening Gentlemen,

Tapio, I have done an initial follow-up on Jerry Murphy’s suggestion in his 2008 NFFS symposium article to use Muscle Wire (Flexinol)
as a DT actuator. This looks very promising. This stuff weighs almost nothing. The diameters that look suitable for our purposes require
roughly the same current as a 1.5 gm servo to actuate. I plan to do more work with this material during the winter building season.
Please let me know your results if you try it out before I can get to it.

OtF’er, I am still pretty overloaded with work, etc., but maybe I can kick back in a few years and have the time to offer some electronics
to the free flight community. However, I really hope some of the existing suppliers will offer an integrated timer/RDT/beacon product for
small models in near future. Starting with the RDT receiver function, it takes very little to add the timer and transmitter beacon
functionality. Perhaps this discussion here will get them thinking.

Tmat, I just scanned over your F1B article in May-June issue of the NFFS Digest. Awesome. I timed Jan Langelius several times at our May
contest and I noted he is now using RDT on his TLG’s just as you describe. Even the smallest TLG I have seen can easily carry a 5 gm
electronics package. My dilemma concerning a MidMat size CLG is the allowable electronics weight for a nominal 20 gm glider. A beacon
transmitter-timer-altimeter can be made really small and lightweight. Adding the RDT receiver is a major increase in size and weight. That
reminds me, I saw one of your photos where you put a fulcrum under the desired CG location and a scale under the end of the glider’s tail
to obtain the inch-grams (love those mixed imperial-metric units) needed in front of the CG for balance. Do you happen to recall what a
typical value is for a MidMat? The electronics are going to have to comprise most of the nose weight. If you need, say, only 10 inch-grams
for balance, adding the receiver would probably be dead weight. If you need 20 inch-grams to balance, the receiver can go along for the
ride with little overall impact on the glider’s weight. I am guessing the receiver can ride OK in a large CLG, but might be iffy for the popular
16 to 18 inch span gliders.

Thermals,

Pappy
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albisko
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« Reply #427 on: June 16, 2011, 03:56:17 AM »

I add some "hi-tech" photos to my picasa  Grin

https://picasaweb.google.com/100588849894345200054/P30BuiltAndFlying#5618698867492845554

palo
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OZPAF
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« Reply #428 on: June 17, 2011, 12:53:12 PM »

Good pics palo and good looking models.Very steep launches as well. How does the low mtd fin model compare to the conventional models.
John
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Tapio Linkosalo
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« Reply #429 on: June 19, 2011, 01:07:33 PM »

We had a small national contest yesterday night, in flat calm conditions and occasional slight drizzle. The airfield that the contest was held on is small (only one runway), so when the drift is not along the runway you are likely to fly into the woods. The good thing is that the "woods" is a swamp, and the trees are small and sparse. Of my three contest flights, every one was out of the runway, but only one in a tree, and that one was 1m tall :-)

But before the contest started I test-flew the new model. Was not quite in a trim, but flew straight downwind for the climb, to enter the woods. And hit a pine tree, more than 20 meters high. Had to leave it there for the contest. After the contest, with the help of a local junior, we managed to throw a towline over the shoot where the model rested, and managed to shake the model down with only minor damage. But not much trimming of that model on that occasion.

The older model was also equipped with VIT, and this was the first occasion I managed to fly it in calm condition. What can I say, wow what a difference. The model tended to be sensitive for launch, and after I built a torque meter the problems were even more severe. Not any more! I wound the 6-strand motors to 600g*cm (it might bear 800, but decided not to break any motors on this occasion), and with the VIT no trim problems whatsoever, just a firm launch straight up, and the model made a steep half-turn spiral before the VIT triggered and the normal spiral climb continued. Even better, I can not throw the model, as the launch position is not as sensitive as it used to be.
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Hepcat
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« Reply #430 on: June 19, 2011, 03:41:06 PM »

Tapio
Thanks for the informative postings that you so often give us.  However just to be absolutely clear in reply #429, am I right in thinking that 'not' in the penultimate line should be 'now'?
John
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Tapio Linkosalo
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« Reply #431 on: June 19, 2011, 11:50:26 PM »

Quite right; it should be "now" (the first one, the second "not" is correct). I.e. it should read:

"Even better, I can now throw the model, as the launch position is not as sensitive as it used to be."

The reason is that without VIT, the model was very sensitive to launch position; launch it too flat or too much bank and it would turn to the right and dive towards the ground before settling to spiral climb while the power fades from burst to cruise. Or launch too steep and you end up on the back after half a loop. WITH the VIT the pitching up is gone, so when launched straight up the model keeps going that way until the power fades off. Towards the end of the burst the prop right pitch starts to kick in, so that even if the launch was slightly to the left, it will start to rotate to the right and establish the right-hand spiral climb. A P-30 has such a small prop that it is practically impossible to have the prop stall, and this helps a lot keeping the model going throught the burst and attaining the proper position for the spiral phase. Also, even at my burst setting, the model is not totally ballistic, but rather I had a couple of flight where the actuator servo jammed (hope to have fixed that now), the tailplane stayed in climb position all the time. The climb seemed a little flatter than normal towards the end of the climb and the glide was steep, slightly diving. But no vertical dive-of-death. SO even during the initial phase the trim of the model is positively stable (meaning that the model corrects errors in the attitude), but due to reduced decalage the looping tendency at higher initial speed is controlled.
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Tmat
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« Reply #432 on: June 20, 2011, 12:35:36 AM »

Tapio,
Do you know how much decalage your P-30 has for the burst and glide?


Tony
-enquiring minds you know.... Grin
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Tapio Linkosalo
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« Reply #433 on: June 20, 2011, 01:35:33 AM »

Do not have the model here at work, but I'd guess about 3 degrees for the glide. In the new model it was 4mm under tailplane that is 70mm wide, i.e. 3.2 degrees. The VIT movement is less than four, maybe 2.5 to 3mm, which means that the decalage will be reduced close to 1 degree for the burst. I can measure later today.
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Tapio Linkosalo
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« Reply #434 on: June 20, 2011, 03:11:26 PM »

The glide decalage of both models is about 3.5mm per 70mm wide tailplane, roughly 3 degrees (measured along the botton tangent of the airfoils, but the LE radius for wing and tail is about the same, so not much difference). For the old model the VIT down incidence is about 2mm = 1.5 degrees, for the new one it is 1mm = 0.8 degrees. However, the latter is not fully trimmed, so the setting may change once I get the right amount of right thrust so that I can get the climb turn right. But the current initial climb with slight left rotation goes straight, so I gather the decalage is about right.

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Tmat
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« Reply #435 on: June 20, 2011, 03:20:37 PM »

Does that mean that for the new one you only reduce the decalage for the climb by 0.8 degrees from the glide setting? That sounds like a very small amount to me. The older model sounds about right to me.


Tony
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Tapio Linkosalo
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« Reply #436 on: June 20, 2011, 11:56:15 PM »

No, the incidence is 1mm = 0.8 degrees, i.e. less incidence than in the old models.  But as the trim is not finished, it might be that changes in thrust angle may still dictate a change in that angle.

I plotted some climb patterns from the two flights I did with the old model where the VIT did not seem to trigger (although I'm not sure of the first one, as that was not coming too fast down in the glide), but anyway the overall altitude did not seem to differ much between the two, and the overall height (50-52 meters) was comparable to climbs with proper incidence. I started to wonder if a much longer VIT setting would work, seems like up to 20 seconds the climb speed was as good or better with VIT down as up. Hm, this suggest a rather different setup from my F1B's where even with step-less transition I run the VIT from burst to glide until 8 seconds. Ok, a F1B has a much larger prop relative to the model size than a P-30.
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albisko
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« Reply #437 on: June 21, 2011, 06:41:18 AM »

more in picasa...

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Tmat
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« Reply #438 on: June 21, 2011, 07:13:54 AM »

Nice! What is the covering?

Tony
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albisko
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« Reply #439 on: June 21, 2011, 07:20:14 AM »

cover is litespan/airspan ,glued balsaloc

http://www.horejsi.cz/Pages/ListProdukt.aspx?kategorie=9&subkategorie=51&fraze=
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albisko
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« Reply #440 on: June 22, 2011, 03:55:06 AM »

new photo Smiley from airfield , model no.3

PGI system is a brilliant set (right-left)
prop -2degrees
wing -2degrees
tail -4degrees
(relative to centre line)
CG 65% of root chord
rubber 3x1mm 6strands
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OZPAF
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« Reply #441 on: June 22, 2011, 05:45:48 AM »

Its interesting to see that you have chosen to use the PGI trim approach after reading tapio's comments. I'm still a student of PGI and i'm wondering what the still air difference would be between your model and the VIT one of Tapio. Both models are fairly similar otherwise. Very nice looking model.
John
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albisko
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« Reply #442 on: June 27, 2011, 04:43:18 AM »

I won Slovak national championship 2011 in category P30 Smiley
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PeeTee
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« Reply #443 on: June 27, 2011, 05:09:21 AM »

Congratulations. Nice looking model, and I  just love underfins. Any chance of publishing a plan or  dimensioned 3 view in the plans section...please Grin

Peter
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albisko
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« Reply #444 on: June 27, 2011, 06:27:12 AM »

Peter,
fuselage,underfin and tail are the same as the previous plans
only  change is in wing dihedral ,centroplan 5degrees and tip 20degrees (relative to centronplan)
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PeeTee
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« Reply #445 on: June 27, 2011, 06:51:23 AM »

Pavol

Many thanks

Peter
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CometsGallor
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« Reply #446 on: September 17, 2011, 12:06:13 AM »

Here is version III of "O' Sugar" P-30. I keep making changes to hopefully improve looks, weight and performance. I am within a few grams of the 40 gram target, and already I have some new ideas for the next version. If it is calm tomorrow it will get its first test glides. Hopefully first flights this Sunday at Eloy AZ for the first contest of our season (to hot to fly during the summer). The fuselage is 1/16 warren truss covered with Microlight. The Stab frame  and wing tips are laminated 1/32.
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Tapio Linkosalo
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« Reply #447 on: September 17, 2011, 01:11:28 AM »

All elliptic, that is pretty!

Is the wing saddle similar to glider tailplane attachment, rubber bands pull the wing forward to a slot in the pylon, and at DT it rotates TE up?
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CometsGallor
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« Reply #448 on: September 17, 2011, 03:08:12 PM »

Tapio,

Thanks I have always liked elliptical shaped wings and stabs.  The DT system uses a drop off wing tethered to the fuselage because here in Arizona we get some very strong thermals and a pop-up tail may not be effective on light models. I have attached a couple detail photos of the pylon. The orange loop is pulled forward which then will pull the white nylon piece in the front snug against the pylon. The wing hold-down rubber bands connect onto the white nylon. When the fuse (in the front of the plane) releases the orange loop, the tension holding the white nylon against the pylon is released and it pivots to release the wing bands.

Bruce
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Eduardo Yamin
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« Reply #449 on: September 18, 2011, 07:26:14 PM »

... Jean Wantzenreither wrote many, many articles on the basics of PGI trim (and the improved TOP variant)...

Tony if you allow me to.

Since the FAI worlds occurred in Embalse i am fully involved to PGI technics by Edgardo Figueroa, perhaps the most dedicated student of Jeans´s materia. I just began to post in my blog some information about it. Just put in (poor) google translator,hope it helps:

My way to view PGI method


My first experience

Elements in the design and trimming

As you can see in this short period i already am an enthusiast and fully satisfied with the results of this technique, I intend to apply it whenever possible in my future models. Incredible not see more of these models flying around ...
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