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lechassin wrote: ↑February 13th, 2020, 5:32 pm some folks are stuck at 1'30" and IMO they're gonna need to pull out all the stops to get much more

Hahaha that's me . Video coming soon, hopefully tomorrow otherwise Sunday for sure.

Also, with 3g, 0.065, and 38 inches, how many winds should I theoretically get? What's the equation to calculate this? I've been winding to 4800, but I think I can probably go up to like 5200.

Xiangyu

is there any way to increase the gear ratio of a winder using legos or something? right now we're using the yellow 15:1 winder and it kinda takes a while to wind.

CookiePie1 wrote: ↑February 13th, 2020, 5:50 pm is there any way to increase the gear ratio of a winder using legos or something? right now we're using the yellow 15:1 winder and it kinda takes a while to wind.

Lego gears winder here: https://www.youtube.com/watch?v=DxaID_o-nko&t=6s

Xiangyu,

I think you're winding well. We don't want to risk breakage in the 8 minute launch window so we don't wind as hard as others who may have a spare motor being wound at the same time or are just more experienced.

Our broken-in 2.8 gram 0.0625 motors hold 4680 knots at 0.6 in.oz. Same motor made on the spot with no break-in reaches 0.6 in.oz at 4350 knots, but the plane flies almost the same amount of time. That's about what you're getting, so if you're using up all those knots on your 3-bladed prop, try slightly higher pitch and/or more flaring to slow the prop down. With three blades you'll still have plenty of thrust (we get an 8 gram bipe to 25 feet in one lap).

To get over 5000 knots and get past two minutes, we need to use 2.8 grams of thinner 0.060 rubber, but then we climb too high to be able to take advantage. We need to unwind 5-600 knots to stay below 25 feet, so no flight time increase locally. We don't dare change anything else because if we make it to State (98 foot ceiling), we think the 0.060 rubber will go 2'20"+.

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Cham,

A 2.5 g .072" motor will take 3,000 turns. One of your biggest issues is that you're not winding fully. Once you do, you will need the torque meter and you will need to backoff wind.

See previous posts in the forum for details.

Brian T
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WOW... We are a really long way off from that. For some reason, ours always start snapping before 2000, no matter how long we make them. We wind them off the plane, stretch to about 4x the length, then wind pretty quickly with a 10x1 winder. However, it always gets super tight in the mid-1000s and snaps then. I will surely try and practice more to fit in more winds because we truly are at a huge disadvantage.

If your motors are consistently snapping at low winds a couple of things to look at:
- Are you using good rubber? Not really much alternative to TAN Super Sport, unless you have a secret supply that has been properly stored of a good, old batch of TAN II.
- Most obvious. Are you lubricating your motors? If not, you will not get turns in.
- Second, less obvious, do you have a bad batch of motors. Not very common with TAN Super Sport nowadays from the source, but if it was stored wrong somewhere along the way, it could happen.
- Third, similar, do you have old motors that have not been stored properly? Heat, ozone, some chemical vapors can really degrade motors.
- Are you letting your motors get dirty? It can be easy to pick up grit that cuts the motor if you drop them and don't clean them off.
Consider getting some fresh rubber, TAN Super Sport. Don't bother with anything else.

Jeff Anderson
Livonia, MI

Using Tan II for WS is borderline sacreligious.

jander14indoor wrote: ↑February 14th, 2020, 1:25 am If your motors are consistently snapping at low winds a couple of things to look at:
- Are you using good rubber? Not really much alternative to TAN Super Sport, unless you have a secret supply that has been properly stored of a good, old batch of TAN II.
- Most obvious. Are you lubricating your motors? If not, you will not get turns in.
- Second, less obvious, do you have a bad batch of motors. Not very common with TAN Super Sport nowadays from the source, but if it was stored wrong somewhere along the way, it could happen.
- Third, similar, do you have old motors that have not been stored properly? Heat, ozone, some chemical vapors can really degrade motors.
- Are you letting your motors get dirty? It can be easy to pick up grit that cuts the motor if you drop them and don't clean them off.
Consider getting some fresh rubber, TAN Super Sport. Don't bother with anything else.

Jeff Anderson
Livonia, MI

Yes, all of the above are possible avenues of investigation. I’ll add a few more. You can safely stretch 5 times relaxed length for winding (broken in and several times used can be stretched 7x, if you want to push it; with good rubber, breakage occurs at 10x stretch). Get more turns in at full stretch. Walk more slowly towards the torque meter while winding (more turns at every level of stretch). If breaking at the knot, improve your knot tying to not abrade rubber. Lubricate more thoroughly (not dripping wet, but just short of this. Be sure to shake your lubricant (Armor All or silicon shock oil) occasionally.

In the last 10 years, I’ve only found two batches of Tan SS that are a little “stiff” and needed about 5% fewer turns. One of these batches flew poor duration and the other batch actually flew same duration as other good batches.

Good job posting this question.

Brian T

One more: don’t try to add more than a few turns at the very end of the process (no stretch).

IMO required viewing for anyone having trouble trimming their plane: https://www.youtube.com/watch?v=me5_fggETag&t=61s

I'm actually posting it to illustrate huge differences in prop performance. In the video above the plane needs 0.7 in.oz torque to reach 25 feet.

Contrast that to this video of our similar design (fixed flat wings): https://www.youtube.com/watch?v=5EKOtW7UqQo . This plane needs only 0.2 in.oz torque to reach 34 feet (climb of 27, a hit with loss of 5, and climb of 2).

Both planes are properly trimmed. The main difference is that the trimmed Ikara prop in the 1st video consumes a lot more power to do a lesser job. Three to five times the power depending how you want to look at things. IMO that's an insurmountable penalty. Anyone wanting to achieve much more than 1 minute cannot use a large diameter prop that is simply cut down.

lechassin wrote: ↑February 13th, 2020, 6:07 pm

CookiePie1 wrote: ↑February 13th, 2020, 5:50 pm is there any way to increase the gear ratio of a winder using legos or something? right now we're using the yellow 15:1 winder and it kinda takes a while to wind.

To get over 5000 knots and get past two minutes, we need to use 2.8 grams of thinner 0.060 rubber, but then we climb too high to be able to take advantage. We need to unwind 5-600 knots to stay below 25 feet, so no flight time increase locally. We don't dare change anything else because if we make it to State (98 foot ceiling), we think the 0.060 rubber will go 2'20"+.

Are you saying you climb higher with smaller (.06 v. .062) rubber? That seems opposite of what I've been learning, ie. if you need more climb you may need a higher weight/cross section rubber? I'm now confused?