High Ceiling Strategy

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klastyioer
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Re: High Ceiling Strategy

Postby klastyioer » April 15th, 2019, 6:18 am

itd be a bold move to start considering tube motor sticks like the ones mentioned earlier in one of these forums
theyre strong enough to prevent any flexing in the stick and are lighter or around the same weight as the sticks youre probably using right now, depending on the wood you choose to use
theyre kinda hard to make not gonna lie on that but there are videos online that can instruct you on how to make the tube itself and with a little bit of research, you can find some jigs for gluing the seam, inserting tissue tubes, and implementing the rear hook, tb, and bearing.
honestly, it's not about the medals. go out there and have fun. make progress, learn a few things, have one heck of a time, because that's all that matters.
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Builder Cult >:)

'17 - Towers, Wright Stuff, rocks
'18 - Towers, Wright Stuff, Mystery Arch, road
'19 - Wright Stuff

Airco2020
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Re: High Ceiling Strategy

Postby Airco2020 » April 15th, 2019, 6:39 am

Well I just wanted to give an update and thank everyone for their help. We had our state competition Saturday. The good news, we had a personal best time with this plane of 2:37. The bad news is we could not get the climb needed for the big building and finished 9th in state. I don't know the top time, but I did time one of the winners practice runs at 3:42. The venue is an armory with a 90ft ceiling in the middle. The winning plane was able to corkscrew almost straight up for the first 30 - 40 ft and then the plane flattened out and kept climbing to right under the rafters.

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Re: High Ceiling Strategy

Postby Airco2020 » April 15th, 2019, 6:40 am

coachchuckaahs wrote:Sorry, I have been offline. My entire flying team went to Round Valley to compete in AMA competition this weekend. One team member came home with a National Record (pending AMA approval).

Coach Chuck


Congratulations!!! You've really got a powerhouse team going!

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Re: High Ceiling Strategy

Postby coachchuckaahs » April 15th, 2019, 9:03 am

It was a blast to fly in a 100' ceiling! My kids all got times right around 10 minutes with their penny planes. Like described by airco, the flights in the high venue were very powerful climbs initially, then leveling off under the rafters. Imagine hitting rafters, repeatedly, at 100'! Only 2 got stuck, and we freed them with helium balloons.

I am happy to report that our testing at home scaled well to the 100' room. We tested with 1/5 rubber, generally 0.5g of rubber and a 2g stick, flying to 20' at home. This gave us an excellent starting point for the 100' ceiling.

Interestingly, the kids found different solutions to get to 10 minutes. The top flyer had very high pitch, with slow prop RPM and thick rubber. That is also the route I took. However, another kid had fairly low pitch, with higher RPM, and she was beating up the rafters. We kept cutting the rubber thinner and thinner, and she reached within a few seconds of the high pitch kid!

All of the kids used the SO log sheets that we have, and analyzed the data, changing one variable at a time. They progressed from 6-7 minutes to over 10 minutes throughout the weekend.

All of this translates directly to SO. The planes were lighter (3.1g), but the processes to improve are the same. It is amazing to see these planes go up like a rocket, then level out and float on the air.

Coach Chuck

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klastyioer
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Re: High Ceiling Strategy

Postby klastyioer » April 17th, 2019, 7:16 am

coachchuckaahs wrote:It was a blast to fly in a 100' ceiling! My kids all got times right around 10 minutes with their penny planes. Like described by airco, the flights in the high venue were very powerful climbs initially, then leveling off under the rafters. Imagine hitting rafters, repeatedly, at 100'! Only 2 got stuck, and we freed them with helium balloons.

I am happy to report that our testing at home scaled well to the 100' room. We tested with 1/5 rubber, generally 0.5g of rubber and a 2g stick, flying to 20' at home. This gave us an excellent starting point for the 100' ceiling.

Interestingly, the kids found different solutions to get to 10 minutes. The top flyer had very high pitch, with slow prop RPM and thick rubber. That is also the route I took. However, another kid had fairly low pitch, with higher RPM, and she was beating up the rafters. We kept cutting the rubber thinner and thinner, and she reached within a few seconds of the high pitch kid!

All of the kids used the SO log sheets that we have, and analyzed the data, changing one variable at a time. They progressed from 6-7 minutes to over 10 minutes throughout the weekend.

All of this translates directly to SO. The planes were lighter (3.1g), but the processes to improve are the same. It is amazing to see these planes go up like a rocket, then level out and float on the air.

Coach Chuck


congrats to them! sounded like a lot of fun im glad yall had a good time
honestly, it's not about the medals. go out there and have fun. make progress, learn a few things, have one heck of a time, because that's all that matters.
-
Builder Cult >:)

'17 - Towers, Wright Stuff, rocks
'18 - Towers, Wright Stuff, Mystery Arch, road
'19 - Wright Stuff

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klastyioer
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Re: High Ceiling Strategy

Postby klastyioer » May 17th, 2019, 5:24 pm

im gonna sound stupid but i dont rly trust this method it sounds low key sketchy and something not necessarily meant for this class of planes, anyone wanna show me proof that it actually works? (words r deceiving)
honestly, it's not about the medals. go out there and have fun. make progress, learn a few things, have one heck of a time, because that's all that matters.
-
Builder Cult >:)

'17 - Towers, Wright Stuff, rocks
'18 - Towers, Wright Stuff, Mystery Arch, road
'19 - Wright Stuff

coachchuckaahs
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Re: High Ceiling Strategy

Postby coachchuckaahs » May 17th, 2019, 5:30 pm

We used this method in 2016 (Wisconsin Nationals), for round valley this year, and for state this year. The method works very well, and is accurate in both altitude and time. It is how we are preparing for nationals this year too.

See me at nationals and I can show you our log book, and you can compare the half flights to the full flights.

Coach Chuck

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klastyioer
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Re: High Ceiling Strategy

Postby klastyioer » May 18th, 2019, 3:38 pm

coachchuckaahs wrote:We used this method in 2016 (Wisconsin Nationals), for round valley this year, and for state this year. The method works very well, and is accurate in both altitude and time. It is how we are preparing for nationals this year too.

See me at nationals and I can show you our log book, and you can compare the half flights to the full flights.

Coach Chuck

will do, ill l be in that room for practically that whole day
honestly, it's not about the medals. go out there and have fun. make progress, learn a few things, have one heck of a time, because that's all that matters.
-
Builder Cult >:)

'17 - Towers, Wright Stuff, rocks
'18 - Towers, Wright Stuff, Mystery Arch, road
'19 - Wright Stuff

izzanom
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Re: High Ceiling Strategy

Postby izzanom » May 22nd, 2019, 6:18 am

I've been looking through the forums for strategies for nationals since there's a 40' ceiling there and ive only flown at 24' max. I keep seeing stuff about the partial motor technique and I was wondering if anyone could explain it to me.

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Re: High Ceiling Strategy

Postby coachchuckaahs » May 22nd, 2019, 9:37 am

izzanom wrote:I've been looking through the forums for strategies for nationals since there's a 40' ceiling there and ive only flown at 24' max. I keep seeing stuff about the partial motor technique and I was wondering if anyone could explain it to me.

That technique has been covered extensively this year, but I'll repeat the key points, as there has been some confusion.

Partial motor testing is a method that allows you to test for a higher ceiling in a smaller gym. In the example we will consider a typical school gym at 24', whereas Nationals is 38-40 feet. Let's use 38 feet to avoid conflict with the lights!

Lets say you plan to use 2.5g of rubber at Nationals. You want to get your plane trimmed for that mass, and figure out the correct rubber linear density (width, or cross sectional area) as well as launch torque. Rather than finding a larger gym for extensive testing, you use a partial motor, half in this case. This method accurately trims the plane and optimizes the rubber.

In this example, us a piece of rubber of the SAME WIDTH, but only 1.25g. Thus, the loop length will be 1/2 of the Nationals loop length as well. REPLACE THE REAR HALF of the rubber with a stick, hook on each end, that also weighs 1.25g (and is balanced so its CG is exactly between hooks). (Note: if you want to be more precise, the wound portion RUBBER alone should be half the mass of the full rubber. Thus, the "half rubber" will weigh slightly more than half the full rubber, as you cannot have half a knot, and you still have two O-rings. So it should be heavier by the mass of one O-ring plus half a knot. But for the heavy rubber we are using this year, this will be a small factor).

Now wind to the SAME TORQUE (peak and unwind to launch) as you will at Nationals.

Launch the plane and watch the RISE of the plane, the difference between launch height and peak height. Double this to know what full rubber will do. Then add this full climb height to your launch height to see full rubber altitude. Adjust your launch torque, rubber width, prop pitch, trim, rubber mass (remember, if you change rubber mass, also change the stick mass to represent the other half of the rubber), and any other parameters to get the correct half rise height to give 38 feet on full rubber. Optimize for time, your time will be approximately half that of full rubber. Amazingly close, assuming your launch point is close to the floor.

Then at Nationals, simply get rid of the stick and make a full loop of rubber, twice the length of your optimized half loop. Now you are carrying the same mass, so trim does not change. You are launching with the same torque, so climb characteristics do not change. But you are winding twice as many turns to get this torque, as you have twice as much rubber. The key is that the mass of the plane stays the same, but the energy stored within that mass is now doubled, so the rise, cruise, and letdown are also doubled.

If you have optimized with a lighter piece of rubber without a stick, then adding additional rubber for ceiling height changes the flying mass, flying speed, trim, climb rate, etc. There is no good correlation to do this.

Coach Chuck

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Re: High Ceiling Strategy

Postby calgoddard » May 23rd, 2019, 7:07 am

As usual, coach Chuck has given an excellent description of the theory and best practice for a particular technique that can be used to maximize flight times of an indoor duration rubber powered stick model, like a Wright Stuff airplane.

I would like to add two subtle points regarding practice with partial rubber motors.

First, the length of the partial motor stick should be approximately half the hook-to-hook distance in his example. This way the rubber motor knots will unwind in the same fashion as they do when the model is flown with a full rubber motor and no partial motor stick.

Second, when flying with a partial motor stick any bad tendencies of the model during the initial climb out (immediately after launch) will only take place for a portion of the time that they would if the model were flown with a full rubber motor and no partial motor stick. For example, if the model is flown with a half motor, it will exhibit any bad tendencies after launch for only half the time that would be the case if it were flown with a full rubber motor. This may mask, or appear to minimize, bad tendencies due to dynamic trim changes. Let me explain further. You will be launching your model at a higher torque for a higher ceiling than the launch torque you used in a lower ceiling. Motor stick bending may cause the model to initially fly flat or even downward for a few seconds before the torque "bleeds off" and the model begins to climb. When launching from a standing position, the model may not hit the ground when launched at a high torque using a half rubber motor. But with the same launch torque and a full rubber motor, it may hit the ground. There are other instances where brief undesirable dynamic trim changes due to high launch torque may be tolerable for 5 seconds, but not 10 seconds, e.g. relatively short duration changes in wing wash-in.

I hope this helps.

Good luck to all you students that are flying at the 2019 SO Nationals.

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Re: High Ceiling Strategy

Postby coachchuckaahs » May 23rd, 2019, 8:56 am

Thanks Cal, both good points. Having a team that relies on half motor testing, I missed the obvious-to-me point of the dummy stick length. On our LPP testing for Round Valley, we used 1/5 Motors. The stick then was 4/5 of the rubber mass, and 4/5 of the hook to hook length. Despite the substantial extrapolation, the full rubber results were quite accurate!

I agree with the comment on bad tendencies on launch. You must have a critical eye on all phases of flight, as the duration of issues is multiplied.

Coach Chuck


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