Rubber Motor Tangling

Locked
Bitconnect
Member
Member
Posts: 30
Joined: February 24th, 2018, 9:23 pm
Division: C
State: NH
Has thanked: 0
Been thanked: 0

Rubber Motor Tangling

Post by Bitconnect » February 23rd, 2019, 6:06 pm

I've been testing with 1/8" rubber and if I remember clearly, each time I've been adding 1 inch to my motors to add in more winds since my planes were basically out of winds when coming down. I've never had this problem ever before, but usually, when the plane is descending, the rubber near the front o-ring finds a way to wrap around the hook/o-ring area and hinder the rotation of the propeller by wedging in between that small space between the prop shaft and the MS. This results in my plane diving steeply at the end even though it has enough winds for a lot more gliding.

My loops are 24" long right now and I've been using the freedom flight kit.

jinhusong
Member
Member
Posts: 168
Joined: March 16th, 2017, 3:34 pm
Division: C
State: CA
Has thanked: 0
Been thanked: 2 times

Re: Rubber Motor Tangling

Post by jinhusong » February 23rd, 2019, 8:23 pm

Bitconnect wrote:I've been testing with 1/8" rubber and if I remember clearly, each time I've been adding 1 inch to my motors to add in more winds since my planes were basically out of winds when coming down. I've never had this problem ever before, but usually, when the plane is descending, the rubber near the front o-ring finds a way to wrap around the hook/o-ring area and hinder the rotation of the propeller by wedging in between that small space between the prop shaft and the MS. This results in my plane diving steeply at the end even though it has enough winds for a lot more gliding.

My loops are 24" long right now and I've been using the freedom flight kit.
I learned that normally, loop length is 1.5 of motor stick size. Maybe you need to increase the stick size?

Jinhu

User avatar
CrayolaCrayon
Member
Member
Posts: 345
Joined: October 25th, 2017, 8:24 am
Division: C
State: PA
Has thanked: 13 times
Been thanked: 4 times

Re: Rubber Motor Tangling

Post by CrayolaCrayon » February 24th, 2019, 5:36 am

That's A LOT of heavy rubber. Try something shorter.
Wright Stuff 2nd 2019 Nationals
USA F1D Team 2020, 2021
1391 Turns

Bitconnect
Member
Member
Posts: 30
Joined: February 24th, 2018, 9:23 pm
Division: C
State: NH
Has thanked: 0
Been thanked: 0

Re: Rubber Motor Tangling

Post by Bitconnect » February 24th, 2019, 7:59 am

I was intentionally making my rubber very long and heavy. Any lighter of a motor and my plane would have gone straight up into the ceiling. I guess all I can do is make a new plane then if the only fix is to make the motorstick longer.

User avatar
klastyioer
Member
Member
Posts: 427
Joined: April 22nd, 2018, 4:46 pm
Division: C
State: PA
Pronouns: She/Her/Hers
Has thanked: 2 times
Been thanked: 1 time

Re: Rubber Motor Tangling

Post by klastyioer » February 24th, 2019, 8:06 am

Bitconnect wrote:I was intentionally making my rubber very long and heavy. Any lighter of a motor and my plane would have gone straight up into the ceiling. I guess all I can do is make a new plane then if the only fix is to make the motorstick longer.
try that
i agree w crayola, thats a crap ton of heavy rubber, like a crap ton
but the making the motor stick longer might help with the clumping thing
you know when you like get too close hook to hook when a motor is wound and it like clumps up?
thats probably why
either make the motor shorter (which it sounds like you cant do) or the stick longer

have you tried thinner and shorter rubber?
it's not about the medals; go out there and have fun. make progress, learn a few things and have one heck of a time; that's all that matters.

Check out Klastyioer's Userpage!

coachchuckaahs
Coach
Coach
Posts: 433
Joined: April 24th, 2017, 9:19 am
Division: B
State: NM
Has thanked: 0
Been thanked: 11 times

Re: Rubber Motor Tangling

Post by coachchuckaahs » February 24th, 2019, 9:19 am

I think the term "lighter rubber" above does not refer to the mass, but rather the width, thickness, density, or other means of measuring the strength of the rubber. Our team uses g/inch. Lighter in this case means thinner.

The fact that you are essentially running out of winds before you land means that your rubber and prop are not matched to your current airframe configuration. There are a number of ways to fix this. First some variables to consider:
  • Airframe configuration: Includes trim setting, and flying mass, where flying mass includes the mass of the rubber. In this case, I would include adding more of the same thickness rubber in airframe configuration. You are making the airframe heavier, which needs more power (more speed) to stay aloft.
  • Prop configuration: This includes static pitch, diameter, blade shape, and if flaring, several more parameters. The easiest to change is pitch, but there are limitations
  • Rubber configuration: This includes primarily the thickness or length density of the rubber (since I put mass with airframe). As you thin the rubber, the loop gets larger to maintain same mass. You could also keep the loop length constant while varying thickness, but then you are changing your flying mass
I do not think you need to jump to a new airframe just yet. When the rubber is coming loose, it is unwound to the point of being useless anyway. Work with the variables above.

If you are using a stock Ikara, especially the non-flaring, then you are likely using too thick rubber. This may not be the case with a flaring or a larger home-built prop. Given a prop and airframe condition, you want to thin the rubber while maintaining mass (or loop length, I prefer mass) until you have some winds at the end of the flight. We often end up with 3/4 to one full row of knots remaining, or about 10% of max winds. Deadstick landings kill your time.

If you get to a closer to ideal rubber thickness/density for your prop and airframe, you can fine tune with prop pitch. If you wanted you could start with pitch, but you may quickly get to stalling the propeller before you absorb enough power (slow the prop down) by adding pitch. But, if you have stock pitch, you can try increasing to see if you can match the rubber you have. Be careful to measure your pitch and certain that both blades match.

Adding more of the same rubber can get you there by loading down the plane, and it may indeed prove to be a good route. However, you likely need to be adding a gram or more to get to a match, and this may end up with a less than overall optimum.

Going to a shorter piece of the same rubber only makes the problem worse, as you are making the plane lighter (it is already over-powered for the current condition), and you are giving up winds (less rubber = less winds).

You are starting to explore the key to improvement: Matching rubber, prop, and airframe. Keep digging.

Coach Chuck
Coach, Albuquerque Area Home Schoolers Flying Events
Nationals Results:
2016 C WS 8th place
2018 B WS 2nd place
2018 C Heli Champion
2019 B ELG 3rd place
2019 C WS Champion
AMA Results: 3 AAHS members qualify for US Jr Team in F1D, 4 new youth senior records

Bitconnect
Member
Member
Posts: 30
Joined: February 24th, 2018, 9:23 pm
Division: C
State: NH
Has thanked: 0
Been thanked: 0

Re: Rubber Motor Tangling

Post by Bitconnect » February 24th, 2019, 11:53 am

Currently, if I understand properly, the reason my rubber is getting tangled is that I'm using way too much rubber for the stock freedom flight motorstick length. The problem here is that decreasing my rubber length would shorten my flight times, as my 24" loops are the optimum loop length for my plane in its current trim settings. I think I will see if increasing my pitch will allow me to use a shorter loop, but I wasn't getting good results with pitches greater or lesser than my current pitch when I was setting my pitch initially.

Locked

Return to “Wright Stuff C”

Who is online

Users browsing this forum: No registered users and 1 guest