Flight Optimization

[PrancingPlane]

After a month and a half of experimentation, I managed to up my plane time from avg 1:00 to now a steady 2 to 2:15 with the occasional 2:30 to 2:45. I have been wondering what I could do to achieve a constant 2:30 or manage to get the occasional 3:00. Thanks BJT4888 for the tips, they really helped(And Pumptato-Cat). Since winning times in my area are around 3:00, I would like to know what next to do. I have finished the advanced and basic trimming tips but one thing I don't know about is "prop pitch" and how to apply it to my plane without the propeller breaking. Regionals is in around a month, so timely help would be much appreciated.

Some info:

Using .085" rubber, not sure the width tho (need to check), with 1.48 and 1.50 motors which are of apprx 12-13 in length
My primary plane (The one which can get the occasional 2:45) weighs like 9.2g and my secondary plane(stable 2:15 on this one) weighs like 8.6g
We fly in a 23 ft gym, but can still get ~1:45 in a 19 ft one (our schools secondary one)
Also, since our gym height is kinda low, we never fully utilize our rubber, we get 'round 0.9-1.1 in oz of torque on em with like 85 winds.
Max turns on the motors are from 95-113 winds using the turns calculator on the NFFS website
Also, I am currently using the stock ikara on my 2nd plane and the stock flaring prop on my first one
If you need any more info, please comment. I really want to place top 3 at regionals this year, would be a great success story for my school after like a 3 year drought of flight talent. So yeah. Thanks for the help and time you all put in and thanks for the help in advance.

Sincerely,
Prancing.

edit: BJT4888 reminded me to add launch torque and backoff turns:
launch torque: wound to ~1.1 but 2-7 backoff turns
Backoff turns, on flights 'round 90% of rubber max, were like 3-8 turns

[bjt4888]

After a month and a half of experimentation, I managed to up my plane time from avg 1:00 to now a steady 2 to 2:15 with the occasional 2:30 to 2:45. I have been wondering what I could do to achieve a constant 2:30 or manage to get the occasional 3:00. Thanks BJT4888 for the tips, they really helped(And Pumptato-Cat). Since winning times in my area are around 3:00, I would like to know what next to do. I have finished the advanced and basic trimming tips but one thing I don't know about is "prop pitch" and how to apply it to my plane without the propeller breaking. Regionals is in around a month, so timely help would be much appreciated.

Some info:

Using .085" rubber, not sure the width tho (need to check), with 1.48 and 1.50 motors which are of apprx 12-13 in length
My primary plane (The one which can get the occasional 2:45) weighs like 9.2g and my secondary plane(stable 2:15 on this one) weighs like 8.6g
We fly in a 23 ft gym, but can still get ~1:45 in a 19 ft one (our schools secondary one)
Also, since our gym height is kinda low, we never fully utilize our rubber, we get 'round 0.9-1.1 in oz of torque on em with like 85 winds.
Max turns on the motors are from 95-113 winds using the turns calculator on the NFFS website
Also, I am currently using the stock ikara on my 2nd plane and the stock flaring prop on my first one
If you need any more info, please comment. I really want to place top 3 at regionals this year, would be a great success story for my school after like a 3 year drought of flight talent. So yeah. Thanks for the help and time you all put in and thanks for the help in advance.

Sincerely,
Prancing.

Pony,
You don’t mention backoff winds and launch torque. Are you winding to 1.1 and launching at 1.1?

You mention .085” rubber. What other rubber densities/widths have you tested and what were the results. I am unfortunately very busy today and can reply more tomorrow. Maybe if Coach Chuck is available, he will get to your question before then.

Brian T

[PrancingPlane]

After a month and a half of experimentation, I managed to up my plane time from avg 1:00 to now a steady 2 to 2:15 with the occasional 2:30 to 2:45. I have been wondering what I could do to achieve a constant 2:30 or manage to get the occasional 3:00. Thanks BJT4888 for the tips, they really helped(And Pumptato-Cat). Since winning times in my area are around 3:00, I would like to know what next to do. I have finished the advanced and basic trimming tips but one thing I don't know about is "prop pitch" and how to apply it to my plane without the propeller breaking. Regionals is in around a month, so timely help would be much appreciated.

Some info:

Using .085" rubber, not sure the width tho (need to check), with 1.48 and 1.50 motors which are of apprx 12-13 in length
My primary plane (The one which can get the occasional 2:45) weighs like 9.2g and my secondary plane(stable 2:15 on this one) weighs like 8.6g
We fly in a 23 ft gym, but can still get ~1:45 in a 19 ft one (our schools secondary one)
Also, since our gym height is kinda low, we never fully utilize our rubber, we get 'round 0.9-1.1 in oz of torque on em with like 85 winds.
Max turns on the motors are from 95-113 winds using the turns calculator on the NFFS website
Also, I am currently using the stock ikara on my 2nd plane and the stock flaring prop on my first one
If you need any more info, please comment. I really want to place top 3 at regionals this year, would be a great success story for my school after like a 3 year drought of flight talent. So yeah. Thanks for the help and time you all put in and thanks for the help in advance.

Sincerely,
Prancing.

edit: BJT4888 reminded me to add launch torque and backoff turns:
launch torque: wound to ~1.1 but 2-7 backoff turns
Backoff turns, on flights 'round 90% of rubber max, were like 3-8 turns

I have been using .080" rubber and .094" rubber, both don't show the same success as .085"
What I mean is that they give like 2 mins on a flight which on .085" rubber would be like a 2:05-2:10

[coachchuckaahs]

Prancing:

It would appear that your next improvements will be matching of the rubber and prop, and improved winding.

On prop and rubber matching, there is a very large difference between 0.085" wide rubber and 0.094" rubber. In addition, there are very large changes in linear density between or within a batch, primarily due to variations in manufactured thickness (as opposed to cut width). Therefore it would be best to characterize your rubber in terms of g/in, or loop length and mass (which you do). Unfortunately you cannot order it this way, but if you continue to log loop length and mass, if you get a grossly different batch you will note it in the data.

You mentioned time differences between 0.085" and 0.094" rubber that you have tried. What is more important is how many winds are left upon landing, if the plane reached the peak height of the facility. If you have significant turns left (more than 1/4 row of knots), you will benefit from wider rubber. If the plane deadsticks (runs out of winds) before landing, you will benefit from narrower rubber. You can make small changes to the prop pitch instead. adding a degree or two to put more load on the rubber (instead of going slightly narrower), or reducing pitch slightly instead of going to wider rubber. While both changing the rubber and changing to prop pitch can help match your rubber and prop, they are not equal. It is a two-parameter puzzle, and if you can only control one parameter you may not be getting to the 2-parameter optimum (time).

As far as winding goes, you are getting 0.9-1.1 torque on 70-80% of predicted max winds. This would indicate you are moving in too quickly. Be sure to stretch to 5-8X (measured) of the resting length of the rubber. Stay at that distance until you see the torque go sharply up, usually around 0.5-0.7 for suitable rubber widths. Then start to walk in while watching primarily the torque. It should not drop, but should ramp up to somewhere around twice the full-stretch torque. If not ramping up you are coming in too quickly. The last 6 inches of walk-in is ONLY for organizing knots. While you have to keep turning in this area, trying to add much turns will break the rubber. You may only get 10-20 turns on the rubber in this last bit! Turns are packed in during full stretch and the first half of walk-in. Watch coach Brian's video for a demonstration (on NFFS website) of winding. Be sure to wind to max torque and then back off to your intended launch torque. This will give you more time, as well as more consistent climbs.

I think these two areas are your low-hanging fruit. In addition when winding is perfected and the prop is matched to the rubber, then look at small changes in decalage (and re-optimize launch torque to get to ceiling) to see if allowing more or less plane speed affects your net time. Once decalage is explored, you can explore small changes in your CG location, re-optimize decalage, and re-optimize launch torque each time you move the CG. Small changes of your CG are worth exploring.

Coach Chuck

[calgoddard]

Prancing -

You said your primary airplane weighs around 9.2 grams. The minimum weight of the airplane under the rules is 8.0 grams. Your airplane is 15% overweight. It is easy to build both a Division B and Division C 2024 Flight event airplane under 8.0 grams using one of the kits like the J & H Aerospace kit with the Ikara prop or the Freedom Flight Models kit. Then add ballast to the front end of the motor stick to bring the model up to a weight of 8.05 grams just to be sure you will pass weighing on scales at a contest if the scales are not calibrated. Reducing the weight of your model by 15% will significantly increase your flight times.

Also, follow the advice of Brian T and Coach Chuck to the letter. Nobody can give you better advice on how to succeed in the Flight event.