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Author Topic: Show us your P-30's  (Read 61658 times)
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Victor
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« Reply #475 on: December 03, 2011, 12:05:24 PM »

Well I cobbled up a blast tube, from a couple sections of my crappie pole that I broke earlier, getting the ON28 out of a tree.  Now I need to get a longer, and stronger pole for "fishing" planes out of trees.  This time I tried a 4 strand 1/8" motor.  Started off with 1000 winds to see if there was any breeze or thermals (I'm avoiding them, given the small field), and got a 1:10 flight on that, with the Square Eagle hitting a soccer goal post on the way down, but no harm done.  Then I wanted to try a 2000 wind, but I think my technique was a little off, I felt like I had to stop at 1800, given the torque noticeably going up.  Probably needed to stretch longer before starting to walk in.  Anyways, there definitely was a bit of power burst, but I know 4 strands should be able to get wound up to 2000-2200, from what I read.  But it worked well, got a 2:30 flight out of that, for an early morning (half hour after dawn) flight.  I didn't fiddle with the trim, I'll wait until I get a full power wind up, and see how it handles it. So far things are looking OK.  I stopped after that, as there was a hint of a little wind starting up, so I decided to wait for another dawn.  This field is pretty small, about 1000 ft. square, so starting in the middle of the field, even a couple miles an hour drift could move the plane into the trees pretty quick, if you get over a two minute flight.  The last flight drifted about 200 feet, which, with 1mph being about 88 feet/minute, shows almost a 1mph drift.  And it drifted in a different direction that the first flight ten minutes earlier, so it wasn't acting too predictable, otherwise I would just launch at one end of the field, and plan on 800 feet of drifting room.  But I'm happy I have a field a couple miles down the road from the house.

Now to start up again with the ON28, I'm going to make some more mods, and will post a picture of it once it is done.

Victor
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crashcaley
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« Reply #476 on: December 03, 2011, 01:43:00 PM »

Victor,  good to hear things are going well.  If the rubber you used is the stuff I sent, then that is why you are feeling that it is very tight.  I doubt it will take more than 2000 turns, and probably less.  But it will deliver more torque than the old rubber.  Another thing about the rubber.  Once you've wound the motor once to high torque, it will not perform quite as well if used the second time.  That is why I usually will add more turns.  That is the way I wound my motor for my Coupe.  First use was at 430 turns, then I went up to 450, and finally 470, to get the same torque.  2.5 was my goal on the torquementer each time, and the rubber needed those extra turns to achieve that torque.  Not scientific, but it worked.
  Look forward to seeing you pseudo ON28.  Smiley Caley
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What's stall speed?  Undecided
Victor
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« Reply #477 on: December 03, 2011, 09:16:04 PM »

Caley,
Yes, that is the rubber you sent me, and you're right, that might be close to the max.  When I went to replace the motor, I found that it had actually broke, with maybe a couple hundred winds left in it, a little bunched up in the back.  So that last wind was a max effort.  I'm sure better winding form would have allowed me to pack more in earlier, but I guess I was right to stop when I did.

I'll keep experimenting with the 4 strand 1/8, and the 6 strand 3/32, and see which works best.

Victor
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crashcaley
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« Reply #478 on: December 03, 2011, 10:09:16 PM »

Victor,  I'm not too up on this, but here goes.  If you are going to use the equivalent of four strands of 1/8 rubber, then you probably can remove a little of the downthrust to compensate for the shallower climbout.  But you need to be careful that you don't put it into a power stall.  I think you just need to play around with the prop incidence until you find the best climbout for the motor you are using. 
  The problem with the longer motor is exactly what you mentioned, bunching towards the rear on some flights.  Did you get any kind of stalling effect on the glide?  If not, then things must be ok.  I use a bobbin over my rear motor peg.  What I use is a piece of aluminum tube that the rear motor tube slides through.  From what I hear, that helps the motor unwind a bit more evenly.  Other, more experienced people can tell you exactly what happens when using a bobbin.  Caley
 
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What's stall speed?  Undecided
Victor
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« Reply #479 on: December 04, 2011, 09:06:43 AM »

Caley,
I went out this morning, with a fresh 4 strand motor.  I've never had the plane properly trimmed yet for the burst, as I never felt like I had a full wind up to see how it would handle it.  With 1000 winds to start, got 1:15.  Second time, I got up to 1750 winds, and got a 2:15 flight.  It seemed to almost stall on the burst, so I checked again.  Third flight I got in 1900 winds, it seemed to work out like you said, at the near max winds the rubber needed a few more turns to reach the same torque.  This time I could clearly see that the plane was climbing too steeply during the burst, as it almost came to a stop, dipped down to horizontal, then started climbing again.  Nothing dramatic like standing on the tail (it can't with only the 4 strand oomph), but clearly needs more down trim.  I don't think it needs any more right trim, as right now the right hand turn during the power phase is about twice as sharp as the turn during the glide (15 second circles under power, and about 30 second circles just gliding). And it is turning, even during the burst, as I was able to see it do the mild stall when it had done a quarter turn and was sideways to me. 

I am having bunching problems, as the third flight saw the plane coming down pretty early, around 1:40.  I looked in the fuz, and saw the motor all bunched up in big knots, near the tail - there was lots of power left, but stuck.  That might explain the couple times I saw the plane bobble, start to bob a little... otherwise, as it was dawn, and there was fog on the ground and almost no air movement at all - the plane was very stable, and circling like clockwork.  So the uneven unwinding is causing some bobbling, it would appear.  I've included a couple pictures, and you can see I forgot to light the fuse for the last flight, but didn't need it luckily.

I thought 4 strands might be a little weak anyways, but wanted to toy with the long run to see how it worked.  I was getting 2 minute motor runs with the 4 strand. Next weekend I'll start back to trimming for the 6 strand 3/32, with a little more down thrust. 

Victor
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crashcaley
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« Reply #480 on: December 04, 2011, 09:31:57 AM »

Sounds like your trim is right on.  Great to hear you having so much success.

  I know of one person who flys the qualifying rounds using a four strand motor because of that very long motor run,  He gets a max each time just on the motor run.  For the flyoffs, he changes to a six strand motor which turns his model into a rocket.  He gets it quite high on the initial burst, and then just hopes.  Of course he has wond quite a few contests with this method, club types that is.

Sounds like you're really having fun.  Keep playing with things.  That is the fun of it all.  Caley
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What's stall speed?  Undecided
OZPAF
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« Reply #481 on: December 05, 2011, 08:21:47 AM »

Hey Victor it sounds like you are having a lot of fun.Thanks for the indepth reports, they are very interesting. On the flying field a 1/2 hr after dawn with frost and 30deg. Thats keen - good on you.
I once built a ON28 for some rels kids in limerick  in Ireland on a holiday. I had to use nail polish(clear) for dope as it couldn't be found for love or money! It was just a little thick as i didn't have a good thinner and the tissue covering was very stiff. It flew well.
John
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RalphS
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« Reply #482 on: December 05, 2011, 11:22:26 AM »

clearly see that the plane was climbing too steeply during the burst, as it almost came to a stop, dipped down to horizontal, then started climbing again.  Nothing dramatic like standing on the tail (it can't with only the 4 strand oomph), but clearly needs more down trim. 
 
Victor  -  not trying to cut in on your talk with Caley but I wonder if just a touch of extra downthrust would cure that problem.  A fully wound 4 strand motor will still provide a good initial climb out depending on the state of the rubber, etc.

I am having bunching problems, as the third flight saw the plane coming down pretty early, around 1:40.  I looked in the fuz, and saw the motor all bunched up in big knots, near the tail - there was lots of power left, but stuck. 

I have found that this problem is usually cured by pre-tensioning the motor.  Are you doing this?

Ralph
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Victor
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« Reply #483 on: December 05, 2011, 07:04:25 PM »

Hello Ralph,

All info, thoughts and observations are appreciated.  Yes, I'm going to try more downthrust, until I see that the plane isn't stalling on the initial burst.  With any luck, I may get out tomorrow morning to try some more.

Not sure what you mean by pre-tensioning, is that the stretch when you first start winding?

Victor
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danberry
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« Reply #484 on: December 05, 2011, 07:18:09 PM »

Try a bit of right thrust instead of the down thrust.
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crashcaley
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« Reply #485 on: December 05, 2011, 11:06:59 PM »

Victor, What Dan is saying is that a tad more right thrust will take it out of the more straight ahead line, causing the model to spriral up.  Just visualise a corkscrew.  That is what your airplane will do on the initial power burst, then it will come out of that into a normal powered flight.  Caley
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RalphS
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« Reply #486 on: December 06, 2011, 05:29:46 AM »

Try a bit of right thrust instead of the down thrust.

Victor said the power turn was fairly tight already.  As downthrust is less "powerful" than side thrust I would still try it first.
We all know that a combination of down and side thrust is usually needed to overcome the burst.  It is getting it just right that takes us years of practice to get right.  So Victor, why not try both?
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RalphS
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« Reply #487 on: December 06, 2011, 05:47:23 AM »

Not sure what you mean by pre-tensioning, is that the stretch when you first start winding?

Hello Victor.  This difficult to explain without using hands!  In the simplest form - as you make the motor up you start with your 4 strands and put the bobbin or tube in place and hold tightly with a rubber band.  Put the motor in the stooge and you should have 2 loops each with 2 strands. In the case of a 4 strand P30 motor wind 100 turns on one loop and attach to the front hook.  Making sure the first loop cannot unwind put 100 turns on the second loop and attach this to the front hook.  Now apply the winder to the front hook, stretch the motor about 50% and allow the motor to unwind itself against the winder pressure and move the winder towards the motor to return to the original length.  This braids the motor into one of the most beautiful sights in aeromodelling.  What it does is to allow the fully wound motor to unwind, but keep tight between front hook and rear fixing in the model, without going slack.  Different models and different motors need different pre-tension turns.   

I bet that somewhere on here there is a better description.   Hope this helps.
Ralph
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« Reply #488 on: December 06, 2011, 10:23:02 AM »

Quote
downthrust is less "powerful" than side thrust I would still try it first.


Hehe .. amazing how approaches diiffer.  Me .. I'd try sidethrust first !

Take your choice    !!      Grin
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« Reply #489 on: December 06, 2011, 11:27:56 AM »

Ralph,  Thanks for explaining pretensioning.  You did it just fine.  Yes, braiding a motor can help to prevent motor bunching.  Just a matter of practise to find out the correct number of turns on the motor for braiding.  Caley 

PS,  Victor, it is a good idea to lube your motor before braiding, but not totally necessary. I've gotten both points of view from others. 
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« Reply #490 on: December 06, 2011, 03:27:25 PM »

But ... it's so fiddly and time consuming doing it to all your motors - and to my mind not as easy to keep them fully lubed thereafter - whereas a few minutes work incorporating a spring stop to the shaft when making the 'front end' takes care of everything.  

Which doesn't help Victor right now, I know .. but something for him to consider for the future
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danberry
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« Reply #491 on: December 06, 2011, 06:17:07 PM »

I really think a 4 strand motor on that plane isn't tghe way to go. The peg to hook distance isn't long enough. The guys using 4 strands and the long motor run are using long fuselages. Also, the plane MUST be at absolute minimum weight to optimize the long run.

A 6 strand motor won't give the bunching problems and will haul the plane up faster. The extra right thrust will pull it through that power stall. Launch it left of the wind.
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Victor
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« Reply #492 on: December 06, 2011, 10:38:52 PM »

Thanks everyone for the helpful comments and the explanations.  In this case, my Square Eagle has a Gizmo Geezer, so that accomplishes the pre-tensioning, right?  There definitely is a bit of slack to take up with the 4 strand.  The positive side is that I get a two minute motor run, so 2:30 flights are a bit easy (if the motor doesn't bunch up).  On the other hand, it really doesn't get that far up, so it probably isn't a good winning strategy for working a thermal.  But we'll see once it is properly trimmed.  The 4 strand doesn't have a rocket burst, so if you don't use it to full efficiency, you are left with a slow climb for my overweight plane.  In my particular tiny field, I like the "stepping my toe in the water" ability to launch a half-max wind flight, make sure there aren't any strong breezes, then do a full wind up, where the model doesn't really fly up too high, and it can land in the field.  I'm trying to avoid any thermals or surprise winds, so I'm usually flying right after dawn, like this morning.

I got out this morning with a 6 strand 3/32 motor, which is probably about the right length...about two or three inches longer than the hook to peg length, and the GG needs slack to function.  A 6 strand 1/8 is actually a little snug, and won't free wheel.  It started raining, and I went ahead and launched it with 1600 winds, after putting in a little more downthrust.  It climbed out better, looked like about the best climbout yet (for these two motor sizes I've been trying).  But I think it got pretty wet, and I noticed it started to do mild stalls during the glide, so it came down pretty fast for the glide phase, for a total of 2 minutes.  It was all wet, so I suspect that that affected the trim.  I got home and weighed it, and after the ride home, it still weighed an extra five grams.  The water was beaded up, so it wasn't making everything soggy, but it definitely was completely covered with beaded up water drops.  I'll wait until dry weather and try again before making a judgment on the current trim.  Funny, on the cold mornings with fog and frost, when it wasn't raining, the tissue did get a little wrinkly and loose (in two spots primarily, the center sections of the stab and wing, where I used the stock tissue from the ON28 kit instead of Esaki.)  The Esaki definitely handles the humidity better than the other tissue.  Dry, this plane weighs 56.2 g with the motor, so it is a bit overweight; but I like how stable and predictable it seems to fly, and respond to trimming adjustments.  

It still turns in 15 second circles under power, I'm not sure if you want it circling any tighter than that; but if I understand the principle right, if given a choice, right thrust doesn't slow down the cruise/climb as much as down thrust, so if you are just trying to handle the initial burst, try to use right thrust, right?

It is fun having a model that flies.

Victor
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danberry
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« Reply #493 on: December 07, 2011, 09:14:01 AM »

Correct on the right thrust. It jist pulls through the stall.
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« Reply #494 on: December 07, 2011, 09:15:53 AM »

Thanks everyone for the helpful comments and the explanations.  In this case, my Square Eagle has a Gizmo Geezer, so that accomplishes the pre-tensioning, right?  

I got out this morning with a 6 strand 3/32 motor, which is probably about the right length...about two or three inches longer than the hook to peg length, and the GG needs slack to function.  A 6 strand 1/8 is actually a little snug, and won't free wheel.
Victor

The gizmo geezer does not pre tension the motor. It works independently of the tension of the motor. Therefore it does not need slack to work. If the GG is not freewheeling under tension there is something wrong with it.
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« Reply #495 on: December 11, 2011, 09:47:54 AM »

This will be my last post in this thread, which is supposed to be about pictures.  But to close this trimming issue out, I got out yesterday at dawn with a 6 x 3/32 motor.  With 1750 winds, I got a nice strong burst, with a tailstand, and a loss of altitude in the stall recovery.  So clearly needed adjustment. Still got around a two minute flight.  The glide is fine again, so the mild stalling last time out was from the plane getting wet.  I put in some downthrust, and got a very mild stall on the second flight, and around a 2:15 flight.  That last flight showed a broken motor, so I put in a fresh one, and it broke right at 1740, so it was very nice to have made that blast tube; first time it has come in handy like that.

This morning, with my last section of 3/32 rubber, and a little more downthrust, got a 2:40 flight; a second one on that motor reached 2:20, but I saw that the motor had broke.  I had brought along a replacement 4 x 1/8, to see if the slightly milder torque might work fine with this trim (and all I have now is 1/8 rubber).  For some reason, it seemed about as tight as the 6 x 3/32, it seemed to be fully wound up at around 1700; I was hoping to get closer to 2000.  So I made two flights with the 4 strand, both around 2:30.  In both cases, the initial burst gave a nice climb, but probably still a touch too steep.  There wasn't a loss of altitude, but a hesitation at the end of the burst, and a lowering of the nose to level flight, until it gained speed and started to climb again.  So it is getting close.  I'd like to see what this plane could do if it was only 40 grams.  I'll probably build a second one, and try to do better.  There are a few things I could do better.

I've got my Majestyk about half done; I'll post some pics when it is finished, in a week or two.  It definitely is more challenging to build than the Square Eagle; and there are a few things I could do better a second time around on that one, too.  But I'm excited to see the Majestyk fly.  It definitely is a lighter plane, and from what I've read, should come out at 40 grams if I do things right.

Derek, I haven't tried the 6 x 1/8 with this Gizmo Geezer; I had one in it while I was waiting for the GG and the winder to arrive.  According to the GG instructions, it is supposed to have some slack for the mechanism to work, but I haven't tried the 6 x 1/8 with the GG, and probably will stick with the 3/32 motor, once I order some more rubber.  

I would like to experiment with tissue over mylar at some stage; all these dawn flights I see some mild slackening of the tissue; even if the mylar/tissue doesn't cure the slackening, it does make me wonder how much humidity change is occurring inside the models and wondering if that could affect trim in the long run.  Maybe I need to put more dope on the tissue, though.  I think I had two coats.  Lots of things to experiment with and learn here.

Victor
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DerekMc
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« Reply #496 on: December 11, 2011, 10:50:00 AM »



Derek, I haven't tried the 6 x 1/8 with this Gizmo Geezer; I had one in it while I was waiting for the GG and the winder to arrive.  According to the GG instructions, it is supposed to have some slack for the mechanism to work, but I haven't tried the 6 x 1/8 with the GG, and probably will stick with the 3/32 motor, once I order some more rubber.  


Victor

Interesting, I have used the GG since they came out. My 6x1/8 motors in a Majestic have always been shorter than the motor peg to front end distance. Never had a problem. I bet it's because they stretch and get longer on the first wind. I don't pre-stretch the motor most of the time. With the stretch of the winding it must have enough slack for the free wheel mechanism to work.
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« Reply #497 on: December 11, 2011, 11:21:02 AM »

The amount of "slack" needed for the Gizmo is a bit misleading for some.  There should not be TENSION on the rubber (when it is COMPLETELY unwound) when initially loaded (unless it has not already been broken in = stretched).  If you look at the motor after the prop has gone into the FW mode, you will see that there are a number of turns left - probably about 50.  These last few turns do very little, if ANYTHING, toward prolonging the flight time and are "sensed" by the GG mechanism, allowing the freewheel to kick in.

The instructions do a very good job of explaining how the system works and can be found/downloaded from the GG website for those who might have "misplaced" them (speaking from personal experience Roll Eyes).
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« Reply #498 on: December 17, 2011, 12:24:29 PM »

Here is my Majestyk, about 99 percent.  I used polyspan for the bottom, along the length of the motor; all the rest is Esaki.  I left some front bays open, in case after weighing empty, and checking the balance with a motor, I needed to add weight, then I would add it along the front in the form of sheeting, assuming that it would most likely be tail heavy.  It turned out to be almost perfectly balanced, just needed maybe a half a gram along the front half, so I am closing it up the way it is.  It turned out to weigh 34.6 grams, with the GG installed and everything in place except for the motor.  I'll just fly it the way it is, 4-5 grams underweight, as I'd make another one if I wanted to compete, and do a better build job.  I have 3 coats of 50/50 dope on the fuse, and 2 coats on everything else.

I can see now where it is all about balsa selection at these low weights; I think the longerons are too flimsy, as it has definite bowing in between the verticals; so for Majestyk number two, I would keep all the rest of the balsa weights the same, but have much stiffer longerons, and since that would add a touch more weight behind the center of gravity, I would make up for it with a little more sheeting along the nose area.  But I can easily see where, with just slight changes in balsa selection, I could have been 5 grams over as easily as 5 grams under.  This was made from the Campbell's kit.

The weather has been a touch windy, so I haven't been out flying; but tomorrow at dawn is supposed to be calm again.  I hope to get out and start some trimming with this, as well as continuing to fiddle with the Square Eagle.

Derek, I installed a 6 x 1/8 for the balance check, and the GG does work that way for me, also; there is mild tension with a fresh motor, but not enough to stop it from working.  Its nice to know I have that option to try for this plane.

Victor
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Dave Andreski
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« Reply #499 on: December 17, 2011, 12:44:48 PM »

Victor,
Very nice job on your Majestyk!
Can we assume that you're happy with the kit from Lee Campbell?
Thanks,
Dave Andreski
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