Wright Stuff C

[lechassin]

A diagram for Wright Stuff has been posted to the national website.

Huh, That's not the approach I would have taken at all. I don't see how that design will do a whole lap the right. I guess the question is whether it is better to have a long flight to the left, and not worry about going right, but I'm betting that two decent flights (one each way) will prevail.

I made a jig yesterday to crank out 3-bladed props is number with varying pitch and blade shapes. I'm skipping the flaring idea for now in favor of determining the best pitch, so the spar is in the middle of the blade. Sanding before gluing works well and the blades no longer off, so thanks for that.

[CrayolaCrayon]

A diagram for Wright Stuff has been posted to the national website.

That prop in the diagram is no where near how small it actually is in comparison to the wing

[andrewwski]

A diagram for Wright Stuff has been posted to the national website.

Huh, That's not the approach I would have taken at all. I don't see how that design will do a whole lap the right. I guess the question is whether it is better to have a long flight to the left, and not worry about going right, but I'm betting that two decent flights (one each way) will prevail.

I made a jig yesterday to crank out 3-bladed props is number with varying pitch and blade shapes. I'm skipping the flaring idea for now in favor of determining the best pitch, so the spar is in the middle of the blade. Sanding before gluing works well and the blades no longer off, so thanks for that.

That diagram isn't intended to be anything indicative of an optimal design, it's just intended to illustrate what the rules mean.

[kinghong1970]

Several of us have built prototypes now, including ones for production. Flight times in the 60-70 second range without too much fiddling. They have very limited power and ANY hint of turbulence blows them out of the sky. Static margins are very low and it's hard to get sustained thrust of any reasonable amount. I have yet to climb one above 20', but like I said, 60-70 seconds, both directions.

The rules are poorly formed resulting in truly ugly airplanes. Doubling the stab span would have greatly eased the trimming difficulty and made for prettier looking airplanes. Basically, the rules are crap because they wanted to screw us all over with difficult to fly airplanes. As a manufacturer I couldn't care less, but as a mentor of umpteen young modelers it makes my blood boil, especially considering who writes these rules. He should know better, and he keeps doing this crap anyway.

hmm... this year's going to be interesting... most gyms have strong HVAC units that they're not so keen on turning off...
i guess we have to buckle up for one heck of a ride.

[coachchuckaahs]

hmm... this year's going to be interesting... most gyms have strong HVAC units that they're not so keen on turning off...
i guess we have to buckle up for one heck of a ride.

Being able to avoid HVAC is critical to clear data generation. Of course, if your Region or State does not turn off A/C, you need to adjust. If this happens, move CG forward, increase power. Last year at Region, 20' ceiling, we had rubber for 30' or more in calm air and never made the ceiling! But for testing purposes, you really need A/C off.

Often admins will say "its computerized, it cannot be turned off". This year for F1D it was critical to turn off. A maintenance person walked through when the A/C was on one morning, and we discussed with him. He can turn it off from his Cell Phone, and has been our best friend since! As a last resort, if you have thermostats that are covered, bring a blue ice pack and place on top of box (in A/C season). In winter, not sure what you can do similarly.Best though to find someone that is friendly and capable of shutting it off.

The rules are indeed tough this year. But, they are what they are. Those who are already building and testing will have a huge advantage in understanding their plane. Get something, anything, in the gym ASAP.

Coach Chuck

[coachchuckaahs]

There are some excellent recommendations on this thread by some very knowledgeable indoor fliers. However, some teams may be obsessing over details rather than focusing on the big picture under the WS 2020 rules.

A near perfectly performing WS 2020 airplane that can only circle in one direction is probably not going to beat a rather ordinary performing WS 2020 airplane that can successfully orbit in both directions and achieve the two-flight total bonus at the competition.

Once you have a WS 2020 model that can reliably orbit in both directions with a predetermined quick adjustment between flights, you can start focusing on optimizing the prop design and/or the rubber motor sizing. Start with a monoplane and try to get it to circle left for 60+ seconds and then circle right for 60+ seconds. Only if you can accomplish this goal would I try adding a second wing to see if a bi-plane can: 1) reliably orbit in opposite directions; and 2) produce a significant advantage in flight time over a mono-plane. You should have little difficulty building a sturdy monoplane that meets the WS 2020 rules that weighs close to the 8-gram minimum weight. Don’t bother testing a bi-plane unless you can build one that also weighs near the 8-gram minimum weight.

I am impressed by the very early work on WS this season. Keep up the good work!

Cal is entirely right, the ability to go both directions will be critical this year, as it will essentially double your score. While I agree that optimization of the prop/rubber combo should wait, our approach may differ somewhat. We will focus on getting a good, stable platform for left circles. We will address the "typical" means of turning (stab tilt, rudder, thrust line, wing warp, wing offset), and see what we can remove without impacting the times badly. I suspect the small prop will have less torque issues, and so some of these may be less important. Once we have a good left-flying plane with minimal required turning features, we will apply those features to a right turn, probably necessitating a new motor stick with adjustability built in. We recognize that the prop is still turning the same way, so some offsets may have to be greater for right turning. After accomplishing this, we will focus on the optimization of prop/rubber.

I would strongly recommend, as Cal indicates, putting off prop/rubber optimization until after getting to this point: A good flying plane that will circle both ways. Some reports of success are seen already using a 6" Ikara prop cut down to 8cm. Be sure to cut so that it fits in a 8cm CIRCLE, not LENGTH. Several kits probably come with this prop setup, and appropriate rubber to get you started.

Coach Chuck

[lechassin]

Our second biplane pictured on page 7 has a 20-25 foot diameter turn both ways and has no structural asymmetries, nor right thrust torque or obvious increased right vs left rudder deflection. The small prop does seem to have negligible effect.

[klastyioer]

We're gonna stick with 1/16" rubber and tweak the motor length and props, no stripper.

The school gym is empty on Sundays and there's usually something going on elsewhere in the building so that solves our gym access problem. We flew the plane pictured on the previous page all day yesterday and we were able to do 1.5 laps either way using leftover 3/32" rubber and the four bladed prop, spectacular climbs to the rafters in 1/2 lap but the power was overcoming our ability to nicely trim the plane, with climbs banking akin to a normal plane, and the motor spent after 15 seconds (no knots remaining).

We have 1/16" rubber now that we can try next Sunday, and we'll use two bladed props to start. In order to facilitate prop changes, I made a new bearing assembly that uses a tiny threaded rod from a micro RC helicopter that the prop threads onto:

The hubs are bits of plastic and carbon fiber from our drawers full of old RC plane stuff, and the blades are SOHO cups, yogurt pots, anything with a curve we like. The blades are reinforced with thin fiberglass cloth. A complete prop weighs 1.2 grams.

We also built a third prototype, 8.1 grams:

In order to reduce banking, we raised the upper wing and added upper fences (we don't want the complexity of dihedral). The tail moment is now 4 times the wing chord, so hopefully the stab trim will hold over a wide power range. The rudder is forward to reduce its effectiveness and ease balancing. Preliminary flights in the house are encouraging with a 1/16" x 17" motor (1.5 hook distance) at 1800 turns (85%), nice gentle climb at full power, slow enough to intercept and catch, gentle descent at 45 seconds.

If this plane flies well, the quickest way I can think of to increase flight times without going past 85% on the motors will be to see if 2x hook distance will fly, to try more winds. If anyone is willing to let me know any other tricks, I'm all ears. I promise we won't win, lol.

cant see the pictures

[MadCow2357]

We're gonna stick with 1/16" rubber and tweak the motor length and props, no stripper.

The school gym is empty on Sundays and there's usually something going on elsewhere in the building so that solves our gym access problem. We flew the plane pictured on the previous page all day yesterday and we were able to do 1.5 laps either way using leftover 3/32" rubber and the four bladed prop, spectacular climbs to the rafters in 1/2 lap but the power was overcoming our ability to nicely trim the plane, with climbs banking akin to a normal plane, and the motor spent after 15 seconds (no knots remaining).

We have 1/16" rubber now that we can try next Sunday, and we'll use two bladed props to start. In order to facilitate prop changes, I made a new bearing assembly that uses a tiny threaded rod from a micro RC helicopter that the prop threads onto:

The hubs are bits of plastic and carbon fiber from our drawers full of old RC plane stuff, and the blades are SOHO cups, yogurt pots, anything with a curve we like. The blades are reinforced with thin fiberglass cloth. A complete prop weighs 1.2 grams.

We also built a third prototype, 8.1 grams:

In order to reduce banking, we raised the upper wing and added upper fences (we don't want the complexity of dihedral). The tail moment is now 4 times the wing chord, so hopefully the stab trim will hold over a wide power range. The rudder is forward to reduce its effectiveness and ease balancing. Preliminary flights in the house are encouraging with a 1/16" x 17" motor (1.5 hook distance) at 1800 turns (85%), nice gentle climb at full power, slow enough to intercept and catch, gentle descent at 45 seconds.

If this plane flies well, the quickest way I can think of to increase flight times without going past 85% on the motors will be to see if 2x hook distance will fly, to try more winds. If anyone is willing to let me know any other tricks, I'm all ears. I promise we won't win, lol.

cant see the pictures

Me neither, originally thought it might be a school filtering policy though that still might be the case.

[xiangyu]

Me neither, originally thought it might be a school filtering policy though that still might be the case.

I'm seeing them alright. Did you refresh your page after you got off school wifi? My school blocks the images but after I get off and refresh they show up.