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Author Topic: Show us your P-30's  (Read 61691 times)
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Tapio Linkosalo
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« Reply #450 on: September 20, 2011, 12:49:58 AM »

Had a nice weather on Sunday morning to eventually log the sinking speed on my new P-30. Well, so I thought. It was flat calm, overcast in the morning then patches of sun, but the flight profiles did not indicate lift until at noon. The logs, however, show some variation in the sinking speed, so I really do not know how reliable these are.

After my previous problems with the digital timers I had re-built the triggers to get maximum movement from the servos, this way trying to overcome there less-than-perfect resolution. This had worked with my older model, that had worked OK for the Finnish Champs a few weeks ago, did not fly the new model there. So it was time to sort that out.

Got 4 or 5 flight ok with the new one, sorted the climb pattern. The logs still suggest maximum climb altitude with 6 strand motors to be a little short of 50 meters, so about the same as the old one does. The glide had a tendency to stall, had to reduse the decalage, and when I got a stable glide is seems to be sinking around 50cm/s. Again about the same as the old one! So it looks like my fancy new model, with elliptical lift distribution and Eggleston profile is no better than the old, with constant wing chord, USA-5 airfoil, and designed some 25 years ago. Phuueiy! After the successfull flights my timer (or servo, rather) started acting up, failing to trigger anything, so the last flights were with straight rudder and no VIT. No DT either, but luckily it was not lifting!

To finalize, I tested the model with a 5 strand motor and no gadgets, flying in "glide" settings. The initial climb was a little too "turny", but after that the model flew OK. Climbed almost 90 meters (2nd pic), and glided in after almost 5 minutes, landing 5 meters away from the start site. Super trims? Naah, from the log you can see that it climbed for 100 seconds, while with a 5-strander the motor run should be 70. Must have been a bubble of lift taking the model that last 30 seconds up, and who knows how much extra it gave for the rest of the climb?

In the picture legends "II" refers to old model, "III" to the new, and the numbers (5s or 6s) give the motor strands. The flight with the old model is given on both graphs as a reference.
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PeeTee
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« Reply #451 on: September 20, 2011, 02:36:48 AM »

Tapio

Sounds as though you had the best of the weather on Sunday (England - wind 15+ mph & rain). Thanks for posting the information, even though it makes slightly depressing reading after all your efforts. I'm about to cover a wing with a 6% version of one of the Eggleston foils and am beginning to wonder if I should have bothered. For P30 sized models perhaps there is more to the USA 5 and NACA 6409 foils than we think - or the prop is a great leveller Wink

Once again, thanks for the info.

Cheers

Peter
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RalphS
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« Reply #452 on: September 22, 2011, 11:26:48 AM »

Lots of people flying P30's it seems.  Lots of variety.  Put any of them into lift and they go up - but can take a time to come down.  My present stable is an old large area model "SE" and a less old (not new!) "No 4 ".  Both have had some successes.  I fly them on 4 strands of 1/8" wound to about 2000 turns.  Wind them tight and they climb well with a nice long motor run.  Both models use the Peck propeller that seems well suited to 4 strands.  The downside of 4 strands is the number of turns needed.  To cut down the winding time I made my winder.  It has a 2:1 gearing above the usual ancient donor drill gear set.  I guess that the time spent making the winder has not yet recovered the time saved on winding - but it is a hobby.
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ricardo
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« Reply #453 on: September 22, 2011, 06:32:22 PM »

Tapio, I give up.  How do you do the logging?
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Tapio Linkosalo
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« Reply #454 on: September 23, 2011, 12:03:24 AM »

RAM3 (SoaringCircuits.com) onboard. Taking the power from the digital timer battery, and replacing the tracking beacon (for fair weather only - no risk of flyways!), so no weight penalty. We have a minimum airframe weight of 50 grams here in Finland, so you can use a bit more gadgets in the model than with 40 grams minimum.

Ps, nice looking winder (and the models, of course). That extra 2:1 gear to the standard hand-drill gear is a great idea!
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applehoney
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« Reply #455 on: September 23, 2011, 12:58:41 AM »

Quote
To cut down the winding time

I use the standard 10:1 yellow case winder for P30's ... takes a 6 strand motor up to 1100/1200 before it starts to grunt, depending upon rubber
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Tapio Linkosalo
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« Reply #456 on: September 23, 2011, 02:16:09 AM »

I hate it when the winder starts to grunt.... My winder (about 1:Cool modified from Horejsi line winch has served me well this summer, the "shortcoming" is that it has similar tran gear as indoor winders, meaning that you stand sideways to the model. This seems OK indoor but feels unnatural outdoors, so I should get/make one similar to that of Spadge to get into "natural" outdoors winding position. Facing the model and the wind.
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Tapio Linkosalo
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« Reply #457 on: November 20, 2011, 10:12:27 AM »

Looks like I need to modify my P-30 props to have a pressure washer, as with tightly-would motors there may be bunching that keeps the rubber tight also during glide - no pro turning. The problem is how to attach the washer? If it is soft-soldered, the joint tends to break loose. If I use silver, the shaft gets hardened and brittle. I would not dare grinding a slot to the shaft to grimp a piece of brass tube onto it. Any other solutions?
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applehoney
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« Reply #458 on: November 20, 2011, 10:30:20 AM »

Hmm, unusual.   I use spring stops on my P30's (as with all rubber models) and soldering a tiny piece of brass tube to the shaft behind the prop, to free it from motor tension, has never given me any problem.
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PeeTee
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« Reply #459 on: November 20, 2011, 10:43:02 AM »

With Igra props I've always used a short piece of brass tube (soft soldered) with a cup washer behind it. I must have made the best part of 100 flights over the years and it's still OK. I now use Gizmo front ends which obviate the need, but they are  rather coarse pitch for 4 strands (I get about a minute motor run with 6 strands of 1/8" SS).

It occurs to me that a tube in a tube used by some on vintage freewheel props might also work. I've never used this method so can't speak from experience.

Peter
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Tapio Linkosalo
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« Reply #460 on: November 20, 2011, 11:04:35 AM »

Ok, maybe a piece of tube does the trick instead of a washer.

I think I have also seen use of tightly wound spiral of piano wire, that needs to be slightly opened to slip the shaft in, and the let tighten to grip the shaft?


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Tmat
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« Reply #461 on: November 20, 2011, 04:39:47 PM »

The coil spring deal is often a wire wheel retainer and probably works. I would prefer to use that as a prop retainer only though. I've used an aluminum wheel collar (1.57 mm I.D or 1/16") and a small flat filed on the side of the shaft instead of brass tubing. It works perfect and is allows me to easily replace the shaft if necessary.
http://www.radicalrc.com/category/Wheel-Collars-263


Tony

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Tapio Linkosalo
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« Reply #462 on: November 21, 2011, 12:38:45 AM »

Ah, neat. When the shaft is replaceable, it does not harm even if the flat part makes the shaft bend more easily. But with a spring retaining the prop, there is no room for the winding loop, so you need to wind without the prop?

What size of shaft are you using? 1mm dia or thicker?

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PeeTee
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« Reply #463 on: November 21, 2011, 02:53:25 AM »

I use 18 swg (1.2mm). I like to sleeve the prop with brass tube, and anything thicker than 18swg takes too much meat off the prop hub for my liking.
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Tmat
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« Reply #464 on: November 21, 2011, 08:26:41 AM »

Winding loop?
You mean you don't wind with a half tube? Grin
Seriously, I do use a half tube (home made) for winding my P-30, but regardless I'd still wind without the prop.
I use 1/16" (1.6 mm) wire for the shaft and it leaves enough meat imo for a bushing in the prop Pete. I just got some teeny tiny 1.5 mm diameter ball bearings for a new prop hub next year so I'll be switching to 1.5 mm wire for the shaft.

Tony
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Tapio Linkosalo
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« Reply #465 on: November 21, 2011, 11:15:22 AM »

No, I do not wind even my F1B's with a winding tube. I do not seem to need one, as I do not tend to break my motors (even though I wind them tight enough that they break several strands on the second wind-up), but I prefer to be ready to launch the model quickly in the fly-off. Therefore I have decided not to adopt the tube. Same with P-30, although there I would on some occasions prefer to have the model protected from the wind...

I have used 1mm shaft for P-30 and it seems to suffice, but would not take the flat for locking the washer. Maybe I should use a larger/longer tube-washer to support the shaft over the flat spot.... Could use carbon for that purpose?
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Hepcat
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« Reply #466 on: November 21, 2011, 04:38:12 PM »

On the matter of the spiral of piano wire to grip on a propeller shaft;  way back, around the early 1940s, many top English flyers used a ‘buckle’ type of freewheel, often fitted behind the propeller, inside a spinner.  As in my sketch below although for convenience my indication of the spinner and noseblock are much too small.

The buckle wire is wound tightly onto the propeller shaft and in such a direction that when the torque load is applied to the buckle it is such as to tighten the coils even more.  The wisdom at the time was that these buckles should not be soldered to the shaft because that would solder the coils together , that would prevent the coils from moving and tightening on the shaft and leave the soldering to take all the load.

I have used this principle on release arms on a Tomy timer winding shaft.  (The type where the arm releases a thread when the shaft has unwound so far.)  The arm can be adjusted for its rotary position by twisting it round the shaft in one direction, in the other direction it locks as the coils wind up.  However the loads in the Tomy application are tiny compared to the torque of a rubber motor and I have never tried an unsoldered freewheel mechanism.  I forgot to mention that locking the buckle against rotation also allows it to take end loads, which are usually much lower than the torques.

John
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Tapio Linkosalo
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« Reply #467 on: November 22, 2011, 02:20:52 AM »

Thanks John,

I think this was the stuff I was trying to recall. Interesting, will have to try that. I also have used the same thing on Tomy timers (even two arms as their relative positions are easy to adjust, the coil is rather free to rotate when twisted to "open" it. Just wonder if it would grip tight enough to take the torque and pull of a P-30 motor?
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Victor
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« Reply #468 on: November 25, 2011, 07:07:26 PM »

Been fiddling with my ON28...Caley had suggested removing the 7 grams of solder I had stuck in the nose of my ON28 to make it balance at the point suggested on the plans.  So I did that, and cut off the back half of the fuselage, and made another rear half, 2.5 inches longer, so that, when I move the wing back to a balance point (with no nose weight), there is more room between the wing and the tail.  So the first pic is the new rear fuz half, compared to the old half, and I also made it wide enough in the back to install the fuse tube without having to cut through the vertical sticks, as I had previously, which left the rear of the fuz too flexy.  Now I also had room to glue in a tiny nylon screw for adjusting the stab.  The last two pics show the reassembled ON28, longer, with the wing moved back until it balances at the point along the wing chord as suggested by the plans.  I also moved the rear motor peg forward one bay. Weight is 43.5 gms without a motor; I stuck in an 8 gram 4 x 3/32 (rubber from the kit) while I'm waiting for the gizmo geezer to arrive and I'll put in a proper length/weight motor.

I took it out this evening for some low power test flights, up to 300 winds.  I could get 30 seconds from 300 winds.  All seems to be in relative order.  I'm hoping to try a new sports park a couple miles down the road, which has 6 back to back soccer fields; it looks to have around 800 x 1000 feet of open space.  Still tight, but maybe a little better for low power test flights until I find a big field.

I tried my Square Eagle out again at the community college across the street, Thanksgiving morning early, as it was quite calm out.  Got 1:10 on 550 winds of the 6 x 1/8, so it seems to be OK so far at half power.  That GG winder I ordered should be here any day now...can't wait to to try it out at full winds.

Victor
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crashcaley
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« Reply #469 on: November 25, 2011, 08:03:46 PM »

Victor,  I did say to remove the nose weight and slide the wing back and forth on the fuselage until it balanced.  But I didn't say to cut the end of the fuse off and add more length.  That is clairification to those who might have thought I told you to cut the thing up and add things.
  Kind of late now, but one thing about having a tail heavy model is usually the tail feathers are heavy.  You have to build light, but still be strong.  That is where wood selection comes in.  You can get some fairly light wood, that still has good strength.  If you cannot get good wood, there are those who build from kits, Guillow's to mention one brand that usually comes with some pretty poor quality wood, or at least used to.  What you can do is sand down the wood a little to lighten things.
   But the problem might not be the wood alone.  You may have to just put one coat on of dope to keep things light.  I've done that.
  But I know others can provide better advice to help you skinny things down on the tail feathers.  I can't remember exactly, but there is a formula that says that for every gram of tail heaviness, you have to add 4 grams of nose weight.  Might be three grams, not sure.  So you don't need to lose a lot of weight in the rear to reduce needed nose weight.  I am still puzzled as to how you got such a heavy tail weight model.  My ON28 was around 55 grams.  Of course, it was one of the very first models I ever built, and I didn't know a thing about wood.  But, if I remember correctly, I never had to add nose weight.  I just moved the wing until it balanced, and it flew just fine, though probably never got more than 90 seconds.
  Good luck on the new version of the ON28.  Hoping you get your G-G soon, as I can tell you are frothing at the bit to wind things up and toss.   Grin  Caley
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Victor
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« Reply #470 on: November 25, 2011, 08:26:05 PM »

Ha!  Yep, cutting off the rear half was my idea...  I noticed the fuz was about 3 inches shorter than my Square Eagle, and I wondered if that was part of the problem...I wonder if it was really meant to balance (at the point located on the plans) with the shorter motor option.  But since my fuz was already so torn up, with about a dozen patches from the blown motor, and the unfinished rear half, which was now having pieces work loose because it wasn't very rigid, I decided it would be a good time to experiment.  I also removed the 1/8" shim under the wing LE, and put it on the fuz flat, like the Square Eagle, which then gave me room to use the rear of the stab to adjust decalage.  I wonder if the only reason that the ON28 had the shim under the wing LE, was because the plan showed the stab glued down flat on the fuz.  So I thought I would experiment with that, too.  We'll see how this all works out, hopefully tomorrow.

Next project will be to tackle the Majestyk; I already have the kit, just need to get started.

Victor
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crashcaley
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« Reply #471 on: November 25, 2011, 08:54:30 PM »

Victor, I think I now know one of the problems.  I do believe the ON28 was originally designed with wire and wheels landing gear.  That is a couple of grams right there.  By leaving that off, it was much easier for the model to become tail heavy.  Of course, the ON28 is probably a better flyer without that landing gear.  If the kit came with the LG, keep the wire and wheels for some other project requiring it.
  I will say that you definitely have a better brain for this than I did at your point.  You are thinking about things like differences in design and trying changes to the model.  I never did that for probably my first five years.  Too busy trying to build things properly.   Grin
  Look forward to your Majestyk.  As I said before, it is a very good flyer.  Build everything staight.  Make sure you follow the instructions for the way to build the wing.  That is a key.  Just to let you know, in dead, and I mean dead air, you should be able to achieve very close to two minutes with a well wound motor.  I typically get 1:53 to 1:57 in those conditions.  Caley
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Victor
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« Reply #472 on: November 26, 2011, 09:03:48 AM »

Caley,
Yes, the plane did come with wire and a wheel for landing gear, which I left off.  I'm fiddling with the ON28 design primarily because it didn't have the sort of features that the Square Eagle has, and I was seeing if I could retrofit those sorts of things like adjustable stab, stab stop, fuse, nylon stab trim screw, etc. onto the ON28 design.  I'm still making plenty of building errors, too; hopefully not repeating too many of them.

If I make the Square Eagle again, the one thing I would change would be to have the rear of the fuz stay just wide enough to hold the fuse tube, so I wouldn't have to cut into the rear of the fuz to install the fuse tube, as the current plan shows.  That way, I could also install a nylon stab trim screw, too, in that gap, like I did for this ON28 mod.  I noticed the Majestyk plans show the rear of the fuz just wide enough to hold the fuse tube, instead of coming to a point, too.  But I can't complain at all about the Square Eagle, so far it has been a very consistent and smooth flier.  Everything I've read says that the undercamber wings, like on the Majestyk, have a better float than the flat bottom wings; but as slow as this Square Eagle floats down, with its flat bottom wing, it is hard to imagine something floating better.  Will see shortly when I try out the Majestyk, and try to make this my best built model yet, and have it right at 40 gms.

This morning's flight at the new location, a sportsplex field, went well with the ON28.  After a few trimming flights (I needed to add a 1/64th ply "plate" under the rear of the stab, and add an extra dental band to reduce the pressure of the nylon screw on the bottom of the stab, which had been boring a hole in the bottom of the stab, and not holding trim) I hand wound it to 500 winds and got a nice 55 second flight, and able to catch it a few feet from where I launched it.  It was starting off too steep, so it wasn't an optimal trim for the climb, but it didn't stall, and the glide seems good now.  I broke a motor again, trying to wind it up again, so back to the building board for some fuz repairs.  But overall, it seems to be going in the right direction.  The sportsplex field, about two miles from my house, has about 1000 x 1000 feet of open area, but with soccer goals dotting the field.  But that is better than trees.

Victor

 
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crashcaley
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« Reply #473 on: November 26, 2011, 01:07:16 PM »

Victor,  You gotta get or make a blast tube so you don't have to keep repairing things.  Well, unless you really enjoy repairing things.   Grin
  Even making a tube from thick cardstock and using scotch tape around it to hold would be better than nothing.  Do that if funds are short for purchasing those clear plastic aquarium tubes you heard about elsewhere.  Caley
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Victor
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« Reply #474 on: November 27, 2011, 09:49:37 AM »

Here is my Square Eagle.  My Gizmo Geezer winder and prop unit arrived yesterday, so, for the first time, I was able to wind it up beyond just a few hundred winds.

I put in 6 strands of 3/32, and worked up to 1600 winds.  Got a couple 2:05 flights at 1600.  It was just starting to get into the power burst on launch, and I had to make some tweaks to the GG.  But further fiddling will have to wait until I make up a blast tube set up.  A nice morning out here, started at about 30 degrees with frost on the ground, no thermals, and almost no wind; maybe a half a mile an hour drift.  A nice morning for trimming flights.

Victor
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