Wright Stuff C

bjt4888
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Re: Wright Stuff C

Post by bjt4888 » January 9th, 2020, 8:40 am

All,

Gearbox by master indoor modeler, Ray Harlan (of Harlan prop hanger fame; same person). See Pictures in Reply #9 of this thread. The pictured gearbox is for electric indoor FF, but could be reversed, as Aircoco did, for rubber power.

https://www.hippocketaeronautics.com/hp ... ic=11797.0

I’m not necessarily recommending this strategy. Just posting for your edification.

Brian T

Airco2020
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Re: Wright Stuff C

Post by Airco2020 » January 9th, 2020, 1:33 pm

bjt4888 wrote:
January 9th, 2020, 8:40 am
All,

Gearbox by master indoor modeler, Ray Harlan (of Harlan prop hanger fame; same person). See Pictures in Reply #9 of this thread. The pictured gearbox is for electric indoor FF, but could be reversed, as Aircoco did, for rubber power.

https://www.hippocketaeronautics.com/hp ... ic=11797.0

I’m not necessarily recommending this strategy. Just posting for your edification.

Brian T
WOW! That is amazing craftsmanship!! That prop alone is wicked! Is that carbon fiber sheet? Pretty impressive! Thanks for finding that reference.

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Re: Wright Stuff C

Post by bjt4888 » January 9th, 2020, 2:45 pm

Air,

Yes, molded carbon cloth, probably actually “carbon veil”; ultra thin cloth. Ray is a master craftsman. Did you note the ball bearings for the carbon rod shafts?

The airplane pictured holds the AMA Category I (ceiling height of less than 8 meters, or 26.3 ft) national record for FF electric, flying 25 minutes and 22 seconds.

Brian T

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Re: Wright Stuff C

Post by Airco2020 » January 9th, 2020, 3:04 pm

bjt4888 wrote:
January 9th, 2020, 2:45 pm
Air,

Yes, molded carbon cloth, probably actually “carbon veil”; ultra thin cloth. Ray is a master craftsman. Did you note the ball bearings for the carbon rod shafts?

The airplane pictured holds the AMA Category I (ceiling height of less than 8 meters, or 26.3 ft) national record for FF electric, flying 25 minutes and 22 seconds.

Brian T
Crazy. That carbon looks so heavy!. Those bearings are tiny! The prop hub is amazing as well. All so perfect and clean. That is an amount of time and detail I'm not sure I could ever achieve by really impressive to see!

nobodynobody
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Re: Wright Stuff C

Post by nobodynobody » January 9th, 2020, 3:05 pm

Today I tested in about a 15 foot ceiling and got better than what I expected: about a minute on each side. My concern right now is that it doesn't climb for long - and it climbs way too fast in that short amount of time. Any suggestions on how I could increase the time it takes to climb, especially when I go to a higher ceiling room?
Class of '23
2020: Astronomy, wright stuff, ping pong parachute, sounds of music
2019: Thermodynamics, potions and poisons, circuit lab, density lab
2018: Thermodynamics, potions and poisons, hovercraft, optics

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Re: Wright Stuff C

Post by Airco2020 » January 9th, 2020, 3:13 pm

nobodynobody wrote:
January 9th, 2020, 3:05 pm
Today I tested in about a 15 foot ceiling and got better than what I expected: about a minute on each side. My concern right now is that it doesn't climb for long - and it climbs way too fast in that short amount of time. Any suggestions on how I could increase the time it takes to climb, especially when I go to a higher ceiling room?
1 min at 15ft sounds pretty good! My perception is that climbing fast is exactly what you want as long as it's not diving, banking, stalling or generally out of control. Climb fast with the early, high torque of the motor and then cruise for as long as possible. You can probably back rubber gm/in (cross section size) and get more winds and therefore more time if you're not having any trouble climbing.

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Re: Wright Stuff C

Post by Airco2020 » January 9th, 2020, 3:19 pm

Airco2020 wrote:
January 9th, 2020, 3:13 pm
nobodynobody wrote:
January 9th, 2020, 3:05 pm
Today I tested in about a 15 foot ceiling and got better than what I expected: about a minute on each side. My concern right now is that it doesn't climb for long - and it climbs way too fast in that short amount of time. Any suggestions on how I could increase the time it takes to climb, especially when I go to a higher ceiling room?
1 min at 15ft sounds pretty good! My perception is that climbing fast is exactly what you want as long as it's not diving, banking, stalling or generally out of control. Climb fast with the early, high torque of the motor and then cruise for as long as possible. You can probably back rubber gm/in (cross section size) and get more winds and therefore more time if you're not having any trouble climbing.
You can probably back OFF rubber...(typing too fast)

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Re: Wright Stuff C

Post by nobodynobody » January 9th, 2020, 6:56 pm

Airco2020 wrote:
January 9th, 2020, 3:19 pm
Airco2020 wrote:
January 9th, 2020, 3:13 pm
nobodynobody wrote:
January 9th, 2020, 3:05 pm
Today I tested in about a 15 foot ceiling and got better than what I expected: about a minute on each side. My concern right now is that it doesn't climb for long - and it climbs way too fast in that short amount of time. Any suggestions on how I could increase the time it takes to climb, especially when I go to a higher ceiling room?
1 min at 15ft sounds pretty good! My perception is that climbing fast is exactly what you want as long as it's not diving, banking, stalling or generally out of control. Climb fast with the early, high torque of the motor and then cruise for as long as possible. You can probably back rubber gm/in (cross section size) and get more winds and therefore more time if you're not having any trouble climbing.
You can probably back OFF rubber...(typing too fast)
Thanks for the suggestions, how do I make it climb more? I tried using thinner rubber and that didn't end well so I will probably stick with .072 for now. I tested in a 30ft tall space with full winds a couple of times and it seemed to not climb after it reached the top, but at comps ceilings will be way higher. Are there any other ways to increase the maximum height? Increasing the torque didn't work for me cause all it did was cause it to stall then nosedive to the ground. Something about incidence or cg?
Class of '23
2020: Astronomy, wright stuff, ping pong parachute, sounds of music
2019: Thermodynamics, potions and poisons, circuit lab, density lab
2018: Thermodynamics, potions and poisons, hovercraft, optics

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Re: Wright Stuff C

Post by Airco2020 » January 9th, 2020, 7:27 pm

nobodynobody wrote:
January 9th, 2020, 6:56 pm
Airco2020 wrote:
January 9th, 2020, 3:19 pm
Airco2020 wrote:
January 9th, 2020, 3:13 pm


1 min at 15ft sounds pretty good! My perception is that climbing fast is exactly what you want as long as it's not diving, banking, stalling or generally out of control. Climb fast with the early, high torque of the motor and then cruise for as long as possible. You can probably back rubber gm/in (cross section size) and get more winds and therefore more time if you're not having any trouble climbing.
You can probably back OFF rubber...(typing too fast)
Thanks for the suggestions, how do I make it climb more? I tried using thinner rubber and that didn't end well so I will probably stick with .072 for now. I tested in a 30ft tall space with full winds a couple of times and it seemed to not climb after it reached the top, but at comps ceilings will be way higher. Are there any other ways to increase the maximum height? Increasing the torque didn't work for me cause all it did was cause it to stall then nosedive to the ground. Something about incidence or cg?
You are correct, it's now in the trim but I'm still learning that as well. I'll state my understanding and let the experts chime in where I'm off base. If you're stalling you either need to move the wing back a tiny bit or reduce wing incidence (angle) or decolage (difference between wing and stab). This year most have the stab flat so you only need to adjust wing. I'd start with making small moves aft with the wing then if it's better optimize the incidence to get good glide. My two cents....might be all wrong!

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Re: Wright Stuff C

Post by lechassin » January 10th, 2020, 6:21 am

I'm no expert but we've noticed some peculiarities to this year's design. We control most of the power stalling with the usual flaring prop, minimal decalage (that still recovers), and down thrust. But we also use the rudder to control the climb rate (whether diving or stalling). It makes our trim procedure somewhat unusual but quick and effective.

The key to this trick is to allow for at least some banking. It's OK if you are offsetting the wings or warping them to keep the plane from banking (that increases efficiency), but for the rudder trick to work, don't fully eliminate banking.

To trim our planes:
1) We set the rudder first to get the radius we want, using partially wound motors. We only worry about climbing or diving enough to do a lap and set the radius. It's important to do this first because you want to maximize the radius based on the venue (to minimize drag), and all other settings follow.
2) Next we set the CG to get a good flat cruise, using partially wound motors. Note that every single one of our designs this year has required about 1mm more decalage going left than right, so anticipate that. We start with about 4mm left and 3mm right and set the CG so the plane cruises flat. At that decalage, recovery from disturbances is adequate but you may need more decalage if your tail boom is short (our tail is light and it's 42cm from the wings). As stated above, put all of the decalage in the wing (incidence), so the stab stays flat. You get 1-2 degrees of down thrust without messing around with the prop hub. Down thrust reduces power stalling.
3) Next we adjust the climb rate using fully wound motors (note that we need to use flaring props, that took care of a lot of the power stalling). After the radius and cruise are nice both ways, we usually have at least one of two problems, both addressed with rudder adjustments:
a) If we launch and descend into the floor (usually going left), we reduce rudder about 1mm. That reduces banking, increasing lift, and solves the problem.
b) If we launch into a power stall (usually going right), we increase rudder 1mm, causing more side-slipping (not banking).That reduces lift and solves the problem.
This procedure can be used repeatedly as you increase torque to get more height.

Thankfully the effect of the final rudder adjustments on turn radius is negligible.

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