Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin  |  Contact Global Moderator
March 28, 2017, 03:44:55 PM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with email, password and session length
 
Home Help Search Login Register
Pages: 1 2 3 [4]   Go Down
Print
Author Topic: Flight times for 2017 SO Wright Stuff  (Read 2645 times)
0 Members and 1 Guest are viewing this topic.
Olbill
Titanium Member
*******

Kudos: 48
Online Online

United States United States

Posts: 2,144



Ignore
« Reply #75 on: March 11, 2017, 02:57:09 PM »

I use this to measure various parts of the building, girders, ducting etc.
https://www.amazon.com/gp/product/B01N64GLDQ/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

I just got one of these. Trying to understand the instructions now.

" The acquiescent edge of the instrument is the back porch".

"The volume measuring result will be display on the main screen finally, previous 3 times result will be display on the first, second, third added line."

Right!
Logged
ceandra
Bronze Member
***

Kudos: 6
Offline Offline

United States United States

Posts: 88



Ignore
« Reply #76 on: March 11, 2017, 08:07:31 PM »

Bill:

Get a kid to help! I guess they did not stop at "New Math", now they have "New English"!

Chuck Grin
Logged
JasperKota
Bronze Member
***

Kudos: 0
Offline Offline

United States United States

Posts: 11



Ignore
« Reply #77 on: March 13, 2017, 07:19:15 PM »

Brian and Don -
Thank you both for the great replies. I had no idea that I wasn't winding enough, then soon realized that I wasn't stretching far back enough while winding which is why rubber had snapped before when going over 120 winds with a 15:1 ratio winder.

I also did not know to relube the rubber - basically I should lubricate each motor again after each hard-wound flight?
I will give some updates once the practice area is open.
« Last Edit: March 13, 2017, 09:08:24 PM by JasperKota » Logged
ceandra
Bronze Member
***

Kudos: 6
Offline Offline

United States United States

Posts: 88



Ignore
« Reply #78 on: March 13, 2017, 07:26:47 PM »

Jasper:

We keep a sandwich-sized ziplock baggie wet with Armourall. It sits on the winding stooge/torque meter, so the kids remember to lube each flight. Keeps it nice and neat, rather than hand rubbing it. Drop the rubber in the bag, squish it around, its ready to go.

Chuck
Logged
dslusarc
Gold Member
*****

Kudos: 18
Offline Offline

United States United States

Posts: 663

Topic starter


Ignore
« Reply #79 on: March 13, 2017, 07:41:11 PM »

e rubber - basically I should lubricate each motor again after each hard-wound flight?
I will give some updates once the practice area is open.

This is what I started doing with TSS, lube it well each wind. Still expect the rubber motor to break eventually so make spares. I just broke my SO motor yesterday winding it up to it to 2000 turns. This rubber does not seem to last long wound  hard many times.
Logged
dslusarc
Gold Member
*****

Kudos: 18
Offline Offline

United States United States

Posts: 663

Topic starter


Ignore
« Reply #80 on: March 13, 2017, 07:49:14 PM »

Quote from: Olbill

I just got one of these. Trying to understand the instructions now.

" The acquiescent edge of the instrument is the back porch".

"The volume measuring result will be display on the main screen finally, previous 3 times result will be display on the first, second, third added line."

Right!

Bill,

That manual is rather amusing. I used the meter to measure the SO gym I fly in this past Thursday as well as the gym we fly in on Sunday. Was able to find the center of the building then measure out the FAI circle then take a height reading. Also was able to measure the available floor space. Triangle feature works pretty good. I was able to measure the ceiling height from across the room by measuring the hypotenuse then the base leg across the room and it calculates the height.  I am happy with it.

Don
Logged
JasperKota
Bronze Member
***

Kudos: 0
Offline Offline

United States United States

Posts: 11



Ignore
« Reply #81 on: March 17, 2017, 03:33:31 PM »

Does the motor have to be wound in a certain direction (clockwise/counterclockwise)? I'm unsure as to what a motor wound backward is.

Practice session went well yesterday! Looking in retrospect I can still wind a more, but glad to say I reached my goal of two minutes.
First run, a minute 40 like usual, although I did wind more than I had before. There was a bit a stalling, so I moved the CG forward a bit (in comparison to the rear wing post)

Next run, 2040 winds, dewound until .42 oz.  Hit the roof twice, came down at 123 seconds with no winds left. Here's the flight: https://youtu.be/A5mfoEwSJIk (ignore the conversation in Chinese in the background  Tongue)

Then decided to switch to the second plane from the FF kit. This one flies more rapidly and has a much smaller circle compared to the other plane. Both planes have the left trailing edge about 3/32" lower than the right, and 1/4" rudder deflection to the left with the stabilizer tilted so the left is a little more than 1/4" higher. This plane was lighter compared to the first, and required more ballast to bring it up to the 7.5 gram minimum.
2055 winds, then dewound to .3 oz torque. 110 seconds, no touch flight, though I launched the plane at my waist. The flight: https://www.youtube.com/watch?v=lv34uVag44g

After that flight, I wound to around 2100, and then dewound to .34 oz. Launched while kneeling, no touch flight at 122 seconds.

Very happy with the results! There's still more room for winds, and I'm hoping to experiment with a flaring blade prop soon. Vanguard P-18 should be arriving over the weekend, so planning on focusing on trimming it next session. Thanks for the feedback from my previous posts!
Logged
calgoddard
Gold Member
*****

Kudos: 13
Offline Offline

United States United States

Posts: 707




Ignore
« Reply #82 on: March 17, 2017, 05:45:24 PM »

JasperKota -

The rubber motor has to be wound in the proper direction in order to produce forward thrust.  This direction depends on whether the propeller is right-handed or left-handed.

A propeller that turns clockwise to produce forward thrust, when viewed from aft, is called right-handed. One that turns counter-clockwise, when viewed from aft, is said to be left-handed.

Almost all propellers used in model airplanes are right-handed.  Sometimes fliers use a right-handed prop and a left-handed prop on a scale model of a twin engine airplane.  

The propeller, and the rubber motor, of a single propeller model are typically wound clockwise, viewed from the front of the model.  Almost all winders have cranks that are turned clockwise in order to wind clockwise. The only exception I can think of is the Rees winder used on larger outdoor scale models.

Both your flights in the videos you posted recently look very good.  I am impressed that your airplane recovers so quickly when it collides with an obstruction. This is a good characteristic to have in an indoor model since it is hard to get the launch torque just right to get a no-touch flight that maxes out just below the beams and like fixtures. This is especially true in WS competition where you only have time for two official flights in the 8-minute Flight Period.

Any flight in a typical HS gym of a 2017 WS airplane over 120 seconds would probably finish in the top three in most regional Science Olympiad competitions. You are doing quite well. Keep up the good work!

In regard to the 123 second flight, how many turns did you back off, and how many turns remained unused when the model landed?  This is critical information that you need to record and analyze after each flight.  It tells you a lot about how well your rubber motor is sized for the prop, air frame, and trim you are currently using.



Logged
Foosier
Nickel Member
*

Kudos: 0
Offline Offline

United States United States

Posts: 1



Ignore
« Reply #83 on: March 21, 2017, 08:50:44 PM »

Cal,

Can you provide more detail on this comment?   "In regard to the 123 second flight, how many turns did you back off, and how many turns remained unused when the model landed?  This is critical information that you need to record and analyze after each flight.  It tells you a lot about how well your rubber motor is sized for the prop, air frame, and trim you are currently using. "

I was able to coach our middle school teams WS squad to a 4th place at state and the High school teams Copter to a 6th place finish at state, but I definitely feel like this is a piece of information I could understand better.  We really worked on trimming and winding and matching the prop to the rubber, but much was trial and error.  Any additional details which would accelerate learning for next year would be appreciated.

Thanks!
Logged
ceandra
Bronze Member
***

Kudos: 6
Offline Offline

United States United States

Posts: 88



Ignore
« Reply #84 on: March 21, 2017, 09:54:45 PM »

Foosier:

There are other posts referenced on the hysteresis of rubber. But the basic story is, lets say you are shooting for 0.25 oz-in of torque. You can wind up to this, and might get say 1500 winds. Or you can wind well past this torque, to near breaking, to say 2500 turns, and then back off say 100 turns and be back at 0.25 oz-in torque, with 900 more turns in the rubber. The winding torque is much higher than the unwinding, and so if you stop on the way up, you miss out on a substantial amount of energy that could be stored in the rubber. On heli's, you only unwind enough to prevent stick warp/breakage or slamming into the ceiling, typically only 30-50 turns. The numbers above are example only, but give you the idea. So wind it hard, then unwind to desired torque. Note also that you want to stretch the rubber while winding. We stretch about 7X the original length, turn about 50-60% of the turns at full stretch, and then walk in while watching the torque. This helps get a lot more winds as well. As does lube.

Generally, if you use up all the rubber (no turns left) in the air, the plane stops flying and loses altitude quickly. Again, generally, people have found that if you use up all the rubber, especially with a low ceiling, you have too thick a rubber, and you are not optimized for time. While the mileage may vary, some have said that having about as many winds left at touchdown as you took off on winding leads to a balanced flight. A full row of knots probably means too thin a rubber. No winds, too thick. Outside of that, optimize based on the stopwatch. If you only have one rubber width, and it is reasonably close (say 1/16" for this year's prop), then you can play with pitch. No winds? Add pitch. Too many winds? Take off pitch.

Still a lot of trial and error, but recording the winds left (or at least an estimate) can help you understand the relationship between winds left and the stopwatch. You can estimate winds by recording "1/4 row of knots" etc., and still get a relationship. Note that also if you change the trim of the plane, you may have to change the rubber (more or less winds left). The winds late in the flight contribute to cruise and letdown. If the rubber is too thin, then late winds cannot hold the plane up, and it lands with too many winds. If too thick, the rubber has too much power for a gentle letdown, you use it up too much in cruise, leaving nothing to help in letdown. A thinner piece would have enough for letdown, and have more total turns (more time).

Use your "additional" fields of your log book for value. Don't stop at 3 extras. My team records, among other things, CG location, decalage, prop number, prop pitch, prop flex (if flaring), peak torque, launch torque, backoff winds, altitude, first lap altitude, rubber width, rubber length, etc. While some (CG, Decalage) may not change much, you may find over the months you did change, and getting back to that "magical" flight is impossible if you did not record the nearly-stationary items as well. Or figuring out what you did change that now put you in the magic. Data is power!

Chuck
Logged
calgoddard
Gold Member
*****

Kudos: 13
Offline Offline

United States United States

Posts: 707




Ignore
« Reply #85 on: March 21, 2017, 10:35:05 PM »

Foosier -

Ceandra has given you good information.

If an indoor model airplane lands "dead stick" (no turns left in the rubber motor) the motor width is too big.

If an indoor model airplane lands with too many unused turns, the motor width is too little.

You will read a lot about "matching rubber to prop."  This is the process of determining the appropriate width of the rubber motor to max the flight time.

Experts go by length and weight of the rubber motor, and not by width. This is because the density of the rubber, and its thickness, vary along its length in a given  batch of rubber, whether it be TAN II or Tan Super Sport, for example. Also, it is not possible to strip rubber to a target width with great precision over the entire length of a rubber motor.    

Ceandra stated "While the mileage may vary, some have said that having about as many winds left at touchdown as you took off on winding leads to a balanced flight." Change - - balanced - - to "close to maximum duration".

Winding rubber motors for SO helicopters is an entirely different endeavor. You can't win the event with a no-touch flight in a typical HS gym. The helicopter has to plant on the ceiling in order to have a chance to win. Backing off winds is not normally done in the SO helicopters event.

  

« Last Edit: March 21, 2017, 10:54:08 PM by calgoddard » Logged
Olbill
Titanium Member
*******

Kudos: 48
Online Online

United States United States

Posts: 2,144



Ignore
« Reply #86 on: March 21, 2017, 11:21:45 PM »

To expound a bit on the preferred way to measure rubber - length and weight - there's actually more to this issue than minor variations of rubber strip thickness and density. All rubber batches that I've come in contact with vary in thickness of the strip. I'm not talking about the width of the strip - whether it be 1/8", 3/32" or whatever. The thickness of rubber strip in the other direction varies by a significant amount. I have 3/02 Tan II rubber that is .039" thick or sometimes even less. I have 5/99 Tan II that measures .047" or more. Just using these two number you come up with a variation in thickness of over 20% for the larger compared to the smaller. That means if one person is flying 1/8" wide rubber that is .047" and another is flying 1/8" wide rubber that is .039" then the first person's motor will be 20% heavier per unit length than the second person's.

Almost every time I go flying some person will ask me what width motor I'm flying. My usual answer is "I have no idea". And this is the actual truth.
Logged
mkirda
Gold Member
*****

Kudos: 10
Offline Offline

United States United States

Posts: 560

WWW

Ignore
« Reply #87 on: March 23, 2017, 02:44:06 PM »

To expound a bit on the preferred way to measure rubber - length and weight - there's actually more to this issue than minor variations of rubber strip thickness and density. All rubber batches that I've come in contact with vary in thickness of the strip. I'm not talking about the width of the strip - whether it be 1/8", 3/32" or whatever. The thickness of rubber strip in the other direction varies by a significant amount. I have 3/02 Tan II rubber that is .039" thick or sometimes even less. I have 5/99 Tan II that measures .047" or more. Just using these two number you come up with a variation in thickness of over 20% for the larger compared to the smaller. That means if one person is flying 1/8" wide rubber that is .047" and another is flying 1/8" wide rubber that is .039" then the first person's motor will be 20% heavier per unit length than the second person's.

Almost every time I go flying some person will ask me what width motor I'm flying. My usual answer is "I have no idea". And this is the actual truth.

And also why loop length and weight are more important things to know.

Last week I knocked together a simple SO model. I wanted to see the times I could get. I built it heavy. Time was well over 3:30 in a 42' ceiling.
Then I discovered that it was still significantly underweight. I glued on a penny, then added some more clay.

Next flight, the prop broke on landing.
I figure that I will laminate them with fiberglass next time. I can take off some clay.
Not sure I will have it with me for West Baden.

Regards.
Mike Kirda
Logged

JasperKota
Bronze Member
***

Kudos: 0
Offline Offline

United States United States

Posts: 11



Ignore
« Reply #88 on: March 25, 2017, 12:46:29 PM »

Apologies for the late reply! In regards to the 123 flight, there were no turns left at landing, and I backed off around 12 turns with a 15:1 winder.
The last practice session frustrated me a bit. Last week, I was able to achieve a no-touch flight backing off to .32 torque. Yesterday, using the same plane with no adjustments made, and backing off to .3 torque still resulted in crashing into the ceiling

During one of the crashes, the wood in front where the propeller was attached snapped, and I glued it back with CA. After testing with other planes, I went back to this one and switched out a stock trimmed down 15 cm ikara propeller for a trimmed flaring blade propeller. 1875 winds, and I backed off 75 winds to .26 torque. 117 seconds, with around 100 winds left after landing. Here is the flight: https://www.youtube.com/watch?v=M0q2AFRmabU

Something I noticed was that the circles were much, much larger (larger than I would like) than previous flights. Note that this is the same plane as the 123 second flight I posted last week. Does the flaring blade propeller also make the circles larger, in addition, to make the plane climb slower? While building the plane, I glued the propeller hook so that it was slightly turned towards the left, which aids in turning. I suspect that after the break, I may have glued the hook back on improperly. Plane still has rudder deflected 1/4" to the left and left stabilizer around 1/2" higher than the right, with a wing warp (left TE slightly lower than right). Should I add more rudder deflection and tilt the stabilizer more?

I was able to test the new Vanguard P-18 I received in the mail and it was very simple to build. Best flight so far is merely 82 seconds, but I haven't flown it much yet.

A bit disappointed, but I'm looking forward to experimenting with the flaring blade prop more and seeing if I can improve my times, as well as consistently fly above 2 minutes without hitting anything. The ceiling is 23 feet, though, and I hope the venue at states to be higher.

Logged
Olbill
Titanium Member
*******

Kudos: 48
Online Online

United States United States

Posts: 2,144



Ignore
« Reply #89 on: March 25, 2017, 08:51:31 PM »

Don't get discouraged about the different power requirements on different days. You have to figure this out every time you fly. My method is to pick a very conservative number for your first flight each day and then adjust from there. Everything can make a difference = air temp, barometric pressure, motor variations - you name it. That first flight is going to determine your direction for the rest of your flying session.
Logged
Pages: 1 2 3 [4]   Go Up
Print
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!