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Author Topic: Show us your P-30's  (Read 61736 times)
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Tapio Linkosalo
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« Reply #275 on: September 20, 2010, 09:26:57 AM »

Sorry, have been in flu, so my English has been below par. Meant Burdov of course. Bunches/knots in the rubber. And I suspect that the fuselage is molded on a round mandrel, but with the laminate between plastic sheets, so that the overlap does not laminate together, but can be opened to release the tube easily from the mandrel. Such small, thin-walled tube would be otherwise quite hard to release from the mandrel. But if the seam is open, then it is simple to take off the mandrel, only to finalize the seam later.
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Tmat
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« Reply #276 on: September 20, 2010, 09:43:14 AM »

Tapio,

I've molded some cylindrical parts with the method you describe and it is quite easy as you say. The Burdov tube might be made that way as the seam if very noticeable.

The knots and bunches are easily accommodated within the motor tube.

Tony
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danberry
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« Reply #277 on: September 20, 2010, 09:53:54 AM »

The fin's clear!
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Tmat
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« Reply #278 on: September 20, 2010, 10:14:06 AM »

Oh yeah, I forgot. Yes, Dan, I'll get on that as soon as possible. Wink Dan sure likes to see some color on a fin...

Tmat
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danberry
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« Reply #279 on: September 20, 2010, 10:21:08 AM »

Actually, I like WHITE on the fin. Shocked
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DerekMc
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« Reply #280 on: September 20, 2010, 10:45:43 AM »

I like aluminized Mylar on the fin. It's amazing how light flashing off the fin can keep it in sight on those long maxes. If the sun is out and it is at the right angle and your timer is not blind...
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« Reply #281 on: September 20, 2010, 11:00:47 AM »

Isn't White a color? (well all the colors?)

Metallized mylar is both good and bad. At the right angle it can flash. At other times it becomes invisible. Maybe white on one side and metallized on the other? Wink

Tmat
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danberry
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« Reply #282 on: September 20, 2010, 02:10:32 PM »

A mirror looks just like what it is reflecting. Any mylar will flash. I'm looking for something that shows against the treeline or the ground. Visible in the upper air isn't the problem. Low to the ground is when it's needed.
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Tmat
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« Reply #283 on: September 20, 2010, 02:32:19 PM »

I agree Dan. At the 2009 World Champs I spotted a very nice all carbon fiber F1B from a Swiss flyer. Very visible in the air overhead (as it was black). However, when the model flew against the backdrop of a mountain he was clocked off because it went invisible!

Tony
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Tapio Linkosalo
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« Reply #284 on: September 20, 2010, 02:50:06 PM »

... or the other way around: At a World Cup just before the Euro- or World Champs, in Odesa, a local chap won the F1B contest with a gull-winged, all white F1B. I do not think the model would have been especially visible in normal conditions, but the fly-off was flown against a real dark thundercloud in the distance, and the white model just shined, unlike all the other models in those conditions...
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danberry
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« Reply #285 on: September 20, 2010, 02:59:54 PM »

Don't get me wrong. The white fin shows up against a blue sky and a lot of clouds. When I see the Wakefields with a brown pylon and a clear fin setting up for a flyoff to the ground, I am simply amazed. There isn't much to see to begin with, help us timekeepers out with some visibility aids. Clear ain't the answer.

My CLGs now have white on the tops of the tip panels and the fin. Easy to see against the ground clutter/background.

Clear ain't the answer. You could not weigh the added mass of putting white ink on one side of a mylar fin.
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Tmat
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« Reply #286 on: September 20, 2010, 03:23:06 PM »

I use fluorescent yellow for the entire wing tip panels on my wakefields Dan. I've always felt that the surface area of the wing tips is far greater than the fin area, so I've not really bothered with the fin. However, most of my models have red fins, and my new Coupe uses a clear fin with bands of fluorescent yellow for visibility.

Visibility is something to pay attention to if you hope to be seen in a fly-off. I'm always amazed when I see a plain, natural polyspan covered model with no high visibility colors at all.

Tony
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DerekMc
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« Reply #287 on: September 20, 2010, 05:21:05 PM »

With all the variables due to visibility and visual timing, how long till somebody proposes using GPS to time flights? I know it is possible with some of the electronic timers.
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« Reply #288 on: September 20, 2010, 10:22:48 PM »

There has been discussion about this already with some of the flyers. Even an altimeter could work if calibrated correctly (starts when the model reaches 2 meters high and shows the time when the model touches down). Using my Airtek Altimeter (from Ken Bauer) I can time my test flights very accurately without a stop watch even if I can't see the model!

Tony
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Tapio Linkosalo
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« Reply #289 on: September 21, 2010, 01:31:20 AM »

We had quite a terrible final fly-off for Finnish Championships in F1A earlier in March, with all models disappearing to the skies in low clouds and darkening evening. This raised quite some discussion on using altimeters to measure flight time. I ended-up taking the technology-sceptic role in the discussion, pointing out possible shortcomings in the new system, and unfortunately the promoters were not too ready to solve the problems....

The biggest concern, IMO, using on-board electronics to measure flight time is the time delay (and to lesser extend, needed equipment) to get the measurements. One may not realize it, but the big advantage of out current, visual-based time-keeping is that it is real-time: once the model lands, you immediately know the score, can compare to others, and can prepare for the (possible) next flight. If, instead, you measure time with a logger onboard, it will be a delay until you retrieve the model, possible have to find it, then bring it back, download and interpret the data. It could easily take one hour after the flight before the results are known, so the time gaps between fly-off rounds would be longer than they currently are. And then there is the question of fly-aways: how long would you wait for the guy, who took the best thermal and was first lost into the cloud, to retrieve his model and claim for victory, until you decide that he cannot find his model (and hence the logger data) in time, instead his visual time remains, leaving him last in the fly-off? What if he finds the model and comes back, but 15 minutes after the time-frame for returning data has passed?

No problem, some suggest. Let's just build a wlan onto the flying field. 10 square kilometres of wlan outdoors? Get real....

Some less serious shortcomings are:
- equipment to read the data from loggers. Every owner of a logger has this, but can it be used for contest purposes; if not, where does the contest manager get 30 units to handle data parallel?
- how to make sure that the logged data is current,, not something planted into the logger beforehand? None of the units that I know use time-stamps in the data...
- I have tried to estimate flight times, and I claim that you can get absolute accuracy of the time only to resolution of about 5 seconds. So, when you probably would use visual timing as the first method, and loggers only as secondary means in case of OOS flight, how can you then match the two methods with different resolution?
- Most loggers are based on microchips with internal resonators. At least some of these (PIC-series) have quite bad temperature stability, which means that there timing may drift a few percent when temperature changes. So I have my doubts about the accuracy of timing of these loggers. Probably for timing purposes you would need specially-made loggers, with separate clock-chips to make the timing accurate enough.

So overall I see that the visual timing can be under certain circumstances a real big problem, but unfortunately there are several problems with using loggers as surrogate that need to be solved. I am not sure if they all can be solved at all.

Sorry for taking this string seriously off topic.
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DerekMc
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« Reply #290 on: September 21, 2010, 01:37:12 AM »

Sorry for taking this string seriously off topic.

My apologies as well. Hardly applies to P-30's!
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« Reply #291 on: September 21, 2010, 10:31:30 AM »

With all the variables due to visibility and visual timing, how long till somebody proposes using GPS to time flights? I know it is possible with some of the electronic timers.

That'l happen about 4 days before I quit the event.
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Tmat
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« Reply #292 on: September 21, 2010, 10:50:10 AM »

Very good points Tapio and good discussion material. We should move the posts to a new topic so that we don't disturb the P-30 thread. Roll Eyes

Tony
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Tapio Linkosalo
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« Reply #293 on: November 06, 2010, 05:46:19 AM »

Several months ago I promised to post a pic of my "Kultasiipi" ("Golden wing") P-30. Finally, here it is.

The design dates back to yearly 1980's, the prototype was my 5th P-30. It turned out to be a good performer, so a couple of years later a friend who ran a small model airplane firm asked to kit the model, and it has been built in quite large numbers in Finland since. Unfortunately when he sold his firm the new owner does not produce it any more.

The kit had a composite fuselage (the same one that we discussed about lately, of kevlar and more lately glassfibre and carbon paper, but alas, it is not produced any more either) and the rest of the structure was balsa. The model is straightforward, with constant-chord wing. Thanks to large dihedral it is very spiral-stable; the model which I fly has no auto-surfaces, and the rudder is campered to make the glide turn, yet it shows no tendency to spiral-in. It could use VIT to make the launch less sensitive, but with careful launch attitude goes well with 6 strands of SS rubber even without.

My version of the model is home-brewn development. It uses the kitted fuselage (actually this is an old one from a model that was built from a kit), while the wing and tailplane are a bit developed further. The ribs are laser-cut, and the wing has 5.5mm Burdov carbon tube for main spar, the tips are with 3.5mm tube. Trailing edge is also "updated" to a carbon strip, therefore there are short carbon caps to support the back of the ribs. The wing is in 2 parts, with a 2mm carbon joiner. Most of all this helps to pack the wing into the model box, in one piece the wing with large dihedral was quite bulky. This version still uses Snoopy timer, but I plan to replace it with a electronic one, as all my larger models now have digital timers.

BTW, our national P-30 rules state a minimum airframe weight of 50 grams (instead of the more common 40). I feel that this rule change was a good one, now even the beginners can built their models to weight, and the slightly larger weight does not harm performance to mention (we can still easily max out with decent rubber), but makes it possible to built a little sturdier models, or add a tracker. 10 grams of additional weight does not harm the sinking speed with DT either, which is a good thing with these tiny models.
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Jukka Juslin
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« Reply #294 on: November 11, 2010, 07:48:01 PM »

Dear All,

Your P-30 planes are absolutely so cute! My P-30 was called "Robin" in early 1990's, but what I recall it was very heavy. Later I have bought RTF PeeWee's, but now I am working a little bit more "own" Peewee and Knarren incarnation.

Here in Finland we have usually in national P-30 contest usually 4 contestants and the competition is once a year. So, proof of this 50 grams concept is not that fool-proof. It is very hard to judge or decide from my point of view, if I would go 40 grams or 50 grams. Certainly I do not believe that adding 25%, which is 10 grams of weight to a light rubber powered airplane wouldn't affect the performance. This must not be true, to believe I need solid hard data with DOE setting. Another point is, that changing one point of the rules might justify changing something more also and this would become a snowball effect. It would be nice to respect the tradition of the class and stable rules, since 1970's or something (just received the FFQ P-30 survey 2010 and read something about the history).

On the other hand, I think it is extremely cool that I think it is possible now to fit Salzer beeper, RAM 3 logger, tracker and timer (burlov) in the model and make it 50 grams. This brings in my motivation for the event. Though the best motivation would be if somebody would compete in this event and fly actively. So, there are pro's and con's in any decisions. What disturbs me is the claim without presenting solid data, that the performance is not affected. But I can forgive that, no hard feelings Smiley.

For national sport in Finland it certainly is a miss that "Kultasiipi" is not produced anymore. This was a nice collaboration with a designer and the producer. Quite rare, at least in Finland - I think. I bought one "Kultasiipi" and still have it, I think, but I never built it - and seems to be will never build it. That is not fault of the plane though Smiley. I am not that big fan of using composites on a P-30, but since we don't practically have any hobbyists in Finland it is better little activity than no activity. What makes making really competitive F1H models for the beginner really hard is the fact that they have gone all-composite. This being said, personally I am not doing any "witch hunt" on composites, I was some sort of pioneer in vacuum bagged carbon+glass fibre wings in Finland in early 1990's. Since then my building accomplishments have been less great Smiley.

I have been building this balsa box fuselaged P-30 and plastic covered (Indoor film, covered with a neon orange spray on the upper surface) lately. I showed my models today in a local sauna evening of the PIK aeronautics club. They thought I am crazy, grown up man building these. But, I guess it might be fun being crazy or different - then Smiley. I don't enjoy building that much though usually and even less with composites nowadays - and chances are pretty sure that I would never finish a composite plane.

I also agree, that it might be good idea to ban moving surfaces during the flight other than the D/T.

Jukka Juslin,
From Finland
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DerekMc
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« Reply #295 on: February 04, 2011, 02:34:25 PM »

Getting ready for the Issacson

Two P30's, a Pirate and a PZaz with matching fuselages, almost ready for the Mylar. Got to love the smell of Velcro glue in the morning!
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« Reply #296 on: February 04, 2011, 03:23:12 PM »

Don't ya just love last minutes? Grin Shocked Wink

Looking good!

Tony
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« Reply #297 on: February 04, 2011, 03:38:32 PM »

Don't ya just love last minutes? Grin Shocked Wink

Looking good!

Tony

Tell me about it! I'll probably finish one of them by the Issacson but you never know Grin
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« Reply #298 on: February 04, 2011, 07:04:45 PM »

Derek, You beat me to my question of whether one of them would fly at the Ike. Would be neat to see one in the bones and mylar/tissue. Cheesy

Caley
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« Reply #299 on: February 04, 2011, 07:12:19 PM »

Derek,

Does the Velcro glue require that you wash the bones before gluing? Haha... noticed the background.

Are the main spars carbon tubes or capped spars? I take these structures have enough torsional rigidity to just use mylar. I'm still planning what I'm going to do when I get time to build a good P-30. I'm almost certain I'm going to build Hannah's Titan--be fun to use his design--but I may modify structure to handle mylar covering.

Five more days!

--Bill
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