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Author Topic: P-30 Spitfire wing questions  (Read 3800 times)
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Red Buzzard
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« Reply #100 on: July 03, 2019, 09:03:49 PM »

Hi Crabby,

That's 10 g. WITH lube. Best weigh 9.5 g. of 1/8 rubber, make it up into six strands and you will know exactly how long that is. Rubber does vary in width and depending on the box can be a little thick-and-thin so giving an exact length as an answer to your question is difficult. Weigh it and you'll know. They will all vary a bit in length. You're practically there, go, go, go.

Bill
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Crabby
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« Reply #101 on: July 03, 2019, 11:47:30 PM »

Just what the doctor ordered. Thanks Bill I’m on it!
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Crabby
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« Reply #102 on: July 04, 2019, 01:13:10 PM »

Final weight 67 grams, 5 of those are ballast! So I kept the Crockett hook in. I am getting good glides with a slight drift to the right. I will post a vid so you can see. Add another 10 grams for rubber and lube=77 grams. I made up a motor with 6 stands of 3/32 x 25 in long tan. ( I don't have any 1/8...should I strip some?) I also made up a motor 3 strands of 3/16 x 29" long. The distance from peg to hook is 18 in. I also made 2 nose blocks one with the geezer, and another with a Z hook and standard ramp freewheel, and a real spinner. I am a little concerned about some excess washout in the right wing. What the "H"! I guess I will bring out the heat gun and try to take some out.

Pic # 2 shows the DT arrangement....all is per the plan, until I get good with all this tackle. I have been a small scale modeler up till now, next up is probably a Senator.
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OZPAF
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« Reply #103 on: July 04, 2019, 06:39:00 PM »

What a wild looking canary Crabby Smiley Looks great - better start hiring some fetchermites!

John
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Crabby
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« Reply #104 on: July 04, 2019, 11:35:15 PM »

Yeah it’s yellow. I wanted (still want) to do black checkerboard but even the least aggressive mask pulls up some yellow. I forgot all about giving the Mylar a good wipe down with iso alcohol. Still gonna go for it with vinyl transfer tape after I know it’s gonna behave. It’s a pretty solid plane though.
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Crabby
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« Reply #105 on: July 05, 2019, 09:07:20 AM »

A few questions. I am making up a six strand motor of 3/32" (1) what is meant by "cross section"? (2) unless I make three identical loops (=6 strands) I am going to have a tag end on both the hook and the peg ends. Am I just gonna tie it off as is or is there something I ought to be doing different? I am sure this is covered somewhere else.
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calgoddard
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« Reply #106 on: July 05, 2019, 10:15:14 AM »

Crabby -

You are making good progress.

If you want to make a 6 x 3/32-inch rubber motor then weigh out a segment of 3/32-inch rubber that weighs 9.8 grams and tie the two ends of that strand into a double knot to form a single loop. Cut off any excess rubber that extends past the knot. Then fold the single loop into thirds.  Put the knotted end so that the knot is behind the motor peg when you load the rubber motor into the fuselage.

At 67 grams, your Spitfire is way too heavy for a 6 x 3/32-inch rubber motor.  It won't climb hardly at all with that size of rubber motor.

"Cross-section" is generally used in terms of a rubber motor as a reference to the overall thickness of the rubber motor.  Thus a standard 6 x 1/8-inch P-30 rubber motor has a cross-section of 3/4-inches.  Six times one-eighth equals three-quarters. These are not exact measurements because TAN II and TSS rubber vary in width and thickness along their length.

You seem to have 3/16-inch rubber.  Try making a 4 x 3/16-inch rubber motor - 9.8 grams before lubing. Weigh out a single strand of 3/16-inch rubber.  Tie a double knot into the two ends. Cut off any excess. Fold the single loop in half to form a 4 x 3/16-inch rubber motor.

If your stab is not popping up, or popping up too slowly, increase the raising force by using shorter and/or more small rubber bands. The stab should pop-up vigorously.  

Get rid of the excess washout in the right wing tip.


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Crabby
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« Reply #107 on: July 05, 2019, 11:03:25 AM »

Good am Cal and thanks for stopping by

Gee that was a simple solution to my 6 strand dilemma thanks ahead for not thinking I am a dummy, just stopped thinking for some reason. OK the 3/16 X 4 should give me a good climb, I will test out the motor for winds, and make up a half tube for winding outside the plane. I made a Kothe torque meter (with good solder points). What is the in./oz. to expect from a motor like that?
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« Reply #108 on: July 05, 2019, 04:48:58 PM »

Crabby,

Make up a short test motor of say, 4 inches long.  16 inches tied together then folded in half like Calgoddard said.  Lube it, and anchor the end of the torque meter (the end that would engage the rubber) to something solid.  Put the test section in the "front" so you can see the pointer climb as you wind.  Hook up the well-lubed test motor and wind it carefully until it breaks.  Note the torque reading.  Don't go over 90% torque on the flying motor.

Enjoy
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« Reply #109 on: July 05, 2019, 05:58:55 PM »

Crabby -

My rubber motor winding memorandum shows that I launch my P-30 models at 5.5 inch-ounces of torque, and sometimes at 6 inch-ounces of torque.  I think others launch their P-30 models at a torque as high as 8 inch-ounces, but my P-30 models do not have VIT.

Flydean1 gave you good advice.  The length of the rubber motor does not affect the maximum torque that a rubber motor will take before it breaks.  So the breaking torque for a 6 x 1/8-inch rubber motor that is 4 inches long will be the same as the breaking torque for a 6 x 1/8-inch rubber motor that is 19-inches long that is made from the same batch of rubber.  He is just showing you a way to save rubber when you test wind to determine breaking torque.

Always wind to predetermined optimum launch torque, and not to a given number of turns.
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Crabby
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« Reply #110 on: July 06, 2019, 09:43:53 AM »

Thanks guys! Good stuff! I am making my half tube from aluminum channel (same dimensions as shelf bracket) today. There is just enough room back at the peg to fit. I also have a sleeve over the peg. I am thinking of peening the ends to retain the rubber loop. I also need to catch the tight wing tip under something to twist and heat some excessive washout out. I think I did it while covering.
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« Reply #111 on: July 13, 2019, 12:06:48 PM »

Good am comrades
I finally heat twisted the excess washout out in the right wing, and made a "half tube". Spent about an hour test gliding, and could not get the thing to quit stalling. I could not allow any more nose weight, so I decreased the wing incidence by about 1/8". After that I was able to remove a shim I had placed under the stab. Now we have a nice gentle glide with a tendency to pull slightly to the right (as seen from the launchers angle). This is probably caused by 1 or both of the following: the freewheeling prop is pulling it, or I have built the fuse slightly crooked to the right. Guests arrive shortly and I have pi$$ed away most of my time allotted to making a full on vegan BBQ. Tomorrow am I am gonna power up some and see what happens. Here are pics of the business end of my half-tube, and a crooked fuse!
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« Reply #112 on: July 14, 2019, 04:50:01 AM »

I hope the BBQ went Ok Crabby but you have to keep a perspective on your time - important things first Cheesy If it is only a slight turn to the right on the glide I doubt whether it will trouble you.

Who is crooked Smiley

John
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Red Buzzard
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« Reply #113 on: July 14, 2019, 12:15:58 PM »

Hi Crabby,

Always hard to tell much on the glide of a freewheeler. You can get close on pitch but the "slight turn" could just as likely be the other way next time. Generally the prop just causes drag in freewheel as there is no thrust to contribute in that mode. Thus perhaps your "stall". Carry on with about 50 hand winds and observations will become meaningful. Don't be surprised by adding more decalage.

Cheers - BBQs are always grand,

Bill
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Crabby
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« Reply #114 on: July 17, 2019, 09:36:13 AM »

Good am Bill, you are correct. I replaced the nosebock and Geezer, with a chunk of clay and got a pretty textbook style glide no turn no stall. The final weight is 47.5gr without the nose assembly, and 64 gr with. I made up a few motors from 3/16" at 9.5gr. It blows up at 8.5 in.oz... At that weight I am going to bring along some 1/4" motors too. I guess I messed up in the tail assembly somewhere. I need 16.5 in the nose. This will be my first P-30 but I really wish I had begun with P-30 long before I got into scale, the biggest change was the switch to torque instead of counting winds. Its all good though. My scale ships are gonna benefit from the experience.

BBQ's are grand, but I had a major paradigm shift when everyone went vegetarian/vegan on me! The cool thing is the flavors are really superior IMHO to the usual BBQ'd beasts we had been eating. I made tempe/beetburgers, and they were out of sight! you would have thought you were eating med rare hamburgers, only better. The swiss cheese was made with pinto beans. John Wayne would have turned pale.
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« Reply #115 on: July 17, 2019, 09:59:30 AM »

Crabby,  PM and/or email sent.
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