How to improve my flight times

[PrancingPlane]

I'm currently using both a Freedom flight helicopter and a J&H Tornado, and both seem to peak around 1:20. Currently, we're using 0.125" rubber in a 9ft ceiling, and for some reason the plane keeps drifting to the end wall. We've experimented with different rubber lengths, such as 12.75", 8.75", 10.25", 9.75", and 9". We normally put about 80 winds on the Freedom Flight and ~85-95 on the Tornado, mainly because our Freedom flight model is very brittle and we don't wish to break it while recording. Our average rubber density is 0.083 g/in. I would like to know how to improve my times to 1:30 or 1:45, or maybe even 2 minutes. Please tell me if I need to include any extra information.

Thank you,

Prancing.

[tacotacocat]

First- several questions
What is your winder ratio? 10-1? 15-1?
Second- how balanced is your heli?
You can test this by drop testing it and seeing if it tilts while dropping
If it isn't stable, that may be the cause of drift.
If it is stable, you probably need a larger area to test or the ceiling may not be optimal (not smooth/popcorn ceiling)
Third- is your 1:20 times coming from flights that have bumped into the wall?
if so, you need a larger area to test:
bumping decreases efficiency

To fix the drift, you could try counterbalancing with clay (SMALL AMOUNTS)

The cause may also be motor shafts not being perfectly straight when bending

Hope this helps
yay

[coachchuckaahs]

What are the masses of your rubber loops?

Please report turns ON THE MOTOR, not on the winder. Note that your log is required to report turns on the motor! There are many different winders.

Please report turns remaining on the motor after the flight.

Please report the number of winds and unwinds on each rubber motor length. If you are putting the same number of turns on each length, then you are likely not getting enough winds. Please watch the winding demo video on the NFFS web site (see Nffs Youtube channel at https://www.youtube.com/channel/UCucmaP ... RTMHX_38YA, or the heli playlist at https://www.youtube.com/playlist?list=P ... n85pKvXQB4. The way you report turns, it does not appear you are winding up to near breaking (max turns) and then backing off to launch torque. The video covers this. Rubber has hysteresis, so if you only wind UP to launch torque you are leaving many winds on the table.

The Nffs site also has a max turns calculator you can use to determine if you are winding to the potential of the rubber. The NFFS website can be found at https://www.freeflight.org/science-olym ... resources/

There are a number of reasons the heli drifts: Room air is moving, top disk is not free to rotate, top disk is crooked, rotor blades vary in pitch angle, rotor shafts are off-axis, etc. However, if both helis drift in the same direction it is likely room air issues

There are even more reasons for short flights, including crooked building, improper rotor pitch angles, improper winding, too small rubber motor (linear density), friction in bearings, too heavy, rubber motor not matched to the heli etc.

Coach Chuck

[PrancingPlane]

Sorry for not including enough data.

To answer tacotacocat's questions:

I use a 10:1 winder, so about 800 winds on the Freedom Flight and ~850-950 on the Tornado

Both Helis seem to be stable when I drop it from my chest height.
The current dimensions of the room I test in are 18 x 15 ft, but I'm working to find a larger area.

The 1:20s are from flights which hit the wall, yes.

For Coach Chuck's questions: 800 winds on the rubber for Freedom Flight, but that is fixed because for Freedom Flight we use only a 12.75" motor.
850-950 winds on the rubber for the Tornado, but depending on the rubber length, it has an uncertainty of +/- 50 winds, we sometimes go to 100, 105 on the 10.25" one.

Based on my logs, I normally have 200 winds remaining on the motor. The way I wind, I wind to about 0.1 or 0.2 in/oz above my launch torque and I back off one or 2 turns to reach my launch torque.


On the 12.75": Winds: 800 ; Unwinds: 20
8.75": Winds: 850 ; Unwinds: 10
10.25": Winds: 1010 ; Unwinds: 30
9.75": Winds: 950 ; Unwinds: 20
9": Winds: 900-910 ; Unwinds: 10

all above are average figures, we sometimes go up or down

Like you said, Coach Chuck, I'm thinking it's more of a room air issue since the Helicopters always seem to be drifting forward and to the left. I'll see if its different when I get another practice venue.

[coachchuckaahs]

You stil are not giving complete data.

Estimating based on your 0.083g/in, the 12.75" loop is likely about 2.25g. If that is the case, breaking winds are 1448, so you should be winding to at least 1300 turns (90%), and probably more as you get the motor broken in. About 60% of this should be at full stretch, and then walk in. Torque should go up to at LEAST 1.6 oz-in, probably more like over 2.0 oz-in. Then back off to launch torque. You may be at twice your launch torque before backing off, depending on what launch torque is safe for your MS (no more than 1.4 on a FFM). Unwinds might be 60-100.

Please review Coach Brian's winding video to see proper winding techniques. Be sure to use lube as well.

200 winds left might be reasonable for a low ceiling. We are seeing 120-150 in a 22' ceiling.

Coach Chuck

[PrancingPlane]

Thank you for your help, both Coach Chuck and TacoTacoCat. I have managed to improve my times to about 1:50. One of the main reasons for my poor flights was that my motorstick was incredibly weak on my freedom flight. Because of this the rotors would bend, late in the flight. I built a new motorstick with the truss to solve this issue. I've also started winding more effectively, so thank you Coach Chuck for that. Currently, I'm going to try to match rubber to helicopter, and I have ordered different thicknesses of rubber. I've also checked different lengths, but on my Freedom Flight Helicopter 12.75" long seems to be a sweet spot, just like how Dave Ziegler said in the kit.

[coachchuckaahs]

Good job improving. Keep trying different rubber loops.

Dave supplies 1/8" stock rubber with the kits. I have 1/8" stock Super Sport rubber including from Dave as well as several boxes I have bought over the last few years. It varies in linear density from 0.071 to 0.083 g/in, so just getting a different cut width does not mean that the density will move in the right direction. If you are not using 1/8" stock, but something close to that, then it was probably cut from 3/16" stock, and the batch code may be different, leading to a different effective linear density. Therefore, be sure to track linear density as you try new motors from differently sourced rubber.

Since you are getting about 200 winds remaining on a low ceiling, you may be close to ideal, but may benefit from slightly higher linear density.

Keep working on your winding. Continue to try to get more winds at full stretch and first half of walk-in until you can approach 90% or more of max turns. it takes breaking rubber, sometimes a lot of it, to learn what is possible. Packing in more turns after walking in will almost always break rubber.

Coach Chuck

[PrancingPlane]

Sorry for waking up this old thread, but if possible, I'd like some help with improving my times past 2:00. Currently, I average around 1:40 to 1:50 depending on the amount of torque I put. Launching around 1.2 or 1.3 normally gets me around 1:50. I have gotten some two minute flights before, being a 2:01 and a 2:03, both on 1.5 torque, but I'm scared to continue launching on that because it sometimes ties up with the truss or shatters the motor when I unwind. (I wind up to 2 and wind down to 1.5) Both helis are FFM. I also pretty much try to copy Coach Brian's winding technique, and our motors are made by holding the rubber with a hemostat, lubing it, tying it and putting a bit of CA glue like you suggested in your video.

Now for info:

All motors are 13 in, 0.125 width rubber, and according to Coach Brian's calculator, the avg linear density is around 0.081 g/in. (We ordered new rubber from Mr. Dave) Masses of rubber loops are 2.25 to 2.3g, mainly because there might be some variation (very tiny) in the lengths of our rubber.
While winding, I normally go up to 1200 turns or so before backing off (using stretch-winding technique) The first FFM's weight is 4.03 g, and the second FFM's weight is 4.22 g. (ik, kinda heavy but we wanted the motorstick to be incredibly strong this time).
I unwind 30-40 turns, slowly and carefully. If desired, I can attach my entire flight log here (some things might be blurred out becoz its my partner and I's names, school, etc...)
Any more info i need to add?

[bjt4888]

Sorry for waking up this old thread, but if possible, I'd like some help with improving my times past 2:00. Currently, I average around 1:40 to 1:50 depending on the amount of torque I put. Launching around 1.2 or 1.3 normally gets me around 1:50. I have gotten some two minute flights before, being a 2:01 and a 2:03, both on 1.5 torque, but I'm scared to continue launching on that because it sometimes ties up with the truss or shatters the motor when I unwind. (I wind up to 2 and wind down to 1.5) Both helis are FFM. I also pretty much try to copy Coach Brian's winding technique, and our motors are made by holding the rubber with a hemostat, lubing it, tying it and putting a bit of CA glue like you suggested in your video.

Now for info:

All motors are 13 in, 0.125 width rubber, and according to Coach Brian's calculator, the avg linear density is around 0.081 g/in. (We ordered new rubber from Mr. Dave) Masses of rubber loops are 2.25 to 2.3g, mainly because there might be some variation (very tiny) in the lengths of our rubber.
While winding, I normally go up to 1200 turns or so before backing off (using stretch-winding technique) The first FFM's weight is 4.03 g, and the second FFM's weight is 4.22 g. (ik, kinda heavy but we wanted the motorstick to be incredibly strong this time).
I unwind 30-40 turns, slowly and carefully. If desired, I can attach my entire flight log here (some things might be blurred out becoz its my partner and I's names, school, etc...)
Any more info i need to add?

Prancingplane,

Good job progressing and studying the resources!

You’ll see on the turn calculator that 1,200 turns is only 80% of breaking turns for a 13” 2.25g motor. To get long flights, you’ll want to follow the instructions in the NFFS resources and wind to 80% on the first use of the motor and then to 85-90% on each use thereafter. This will take you to over 2.0 inch ounces for max torque. Backoff to the launch torque that you are comfortable with. Launch torque above 0.8 is the minimum that my new students use and the FF Helis appear to be rather unstable with launch torque above 1.3.

As your Heli is 5% above minimum weight it will get about 5% less duration than a 4.0 g Heli. Based on this, the maximum duration for your Heli with a 90% winding and launch torque of 1.2 or 1.3 is about 2:20. Weight really matters. The FF kit fuselage with the truss threads installed and the noses wrapped with thread and glue are plenty strong enough for this winding and should allow you to build to 4.0g.

Keep up the good work!

Brian T

[coachchuckaahs]

I agree with Coach Brian that it appears your winding is a bit low. Best performance will be after a few hard runs on a motor, and at that point you should be close to the max winds calculation. If you are not getting to this point before torque gets over 2.0, then revisit your winding technique. In particular, you could be walking in too soon. You cannot add many turns once you have walked in because the rubber is all sequestered in knots. Second half of walk-in is only organizing knots, not adding a lot of turns. Getting that extra 20% of turns will get you a lot more time in the air.

Good job on your build. I believe you are close on mass .

Once you improve your winding, you will want to try varying the mass of rubber by increasing or decreasing the length, looking for optimum. While you can fit more winds in a longer piece of rubber, it also adds more mass that must be supported, so there is a clear optimum.

Coach Chuck