RunRyder RC
WATCH
 1 page 901 views Post Reply
HomeScale✈️AircraftScale HeliScale Helicopter Main Discussion › MD 500 Vibrations
02-22-2010 02:40 PM  10 years ago
Topic Vote0Post 1
ivorz

rrNovice

Heli Wonderland

MyPosts All Forum Topic
MD 500 Vibrations
I recently finished putting together and 500 size MD 500D and I have been having problems with vibrations when the heli is in the fuselage.

I checked the heli and flew it prior to inserting in to the fuse.

When I start to spool up the heli sounds/looks perfect. It even lifts off into a hover. Then suddenly, it sounds like it is about to come apart.

I had some video where I could see the housing around the head vibrating.

What I would like to know, is what is the best way to fix this.
I have had recommendations of inserting foam padding between the fuse and frame at the top. I was also thinking of securing the fuse to the frame (at the top) with some typr of solid mount.

Is it better to use foam padding or something rigid to secure it tight.

Also what are these vibs coming from. I have checked everything outside the fuselage and the heli is smooth as silk.

Thanks in advance.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
02-22-2010 03:04 PM  10 years ago
Notar

rrKey Veteran

Taxachussetts

MyPosts All Forum Topic
If you do not have any mounts securing the upper part of the mech to the fuse, add some. That more than likely is the cause of the bad vibs you get. Make it a rigid mount, not flexible. Also, most times you cannot fly a fuse at the same head speed you have as in pod and boom. The fuse will not tolerate it. Try lowering the head speed down a couple of 100rpm.
Joe
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
02-22-2010 03:15 PM  10 years ago
ivorz

rrNovice

Heli Wonderland

MyPosts All Forum Topic
thanks for the reply,

What head speed would you recommend. I have been trying to find out what others are flying, but cannot seem to find anything.

I am running about 2500 rpm. On my larger scale helis, (30 size I run about 1700rpm) but I am not sure what to run on the 500.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
02-22-2010 03:32 PM  10 years ago
Antsis

rrApprentice

, Australia

MyPosts All Forum Topic
Looking at your HS figure, I'm guessing this is an electric? I had a similar problem on my MD500/Trex600e which looked like unbalanced blades. Turned out it was just a case of one blade being slightly tighter in the grips.
I am running about 2500 rpm. On my larger scale helis, (30 size I run about 1700rpm) but I am not sure what to run on the 500.
You do not really need to run this high. My electric setup has the standard 600XL motor and 75A ESC, helical gears (188T main, 11T pinion), and at 60% throttle, I'm getting a HS around 1550-1600. The model is quite happy to fly at that rpm.
Ant
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
02-22-2010 03:33 PM  10 years ago
Notar

rrKey Veteran

Taxachussetts

MyPosts All Forum Topic
Try to get to 1500-1650 and see what happens after you make the upper fuse mounts. If the vibs are gone, increase the rpm slightly to get the machine back to where it handles ok for you, as lower rpm makes the machine feel slightly sluggish compared to 2k on the head.
Joe
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
02-22-2010 05:54 PM  10 years ago
ivorz

rrNovice

Heli Wonderland

MyPosts All Forum Topic
I don't think the t-rex 500 will fly at such a low head speed (1500-1600).

Anyone with a 500---what head speed are you running in your scale ship
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
02-22-2010 09:53 PM  10 years ago
Antsis

rrApprentice

, Australia

MyPosts All Forum Topic
What main gear/pinion are you running? You want to lower the HS enough to avoid nodding, but also keep the motor working at its best efficiency.
The standard 500 has a 162T main and, with the stock 1600KV motor and a 6 cell, 25-30C lipo, to get 2500 on the head, you must be using a 14T pinion. Have a look at what smaller pinions are available. You want a 10T or 11T which will drop the HS to 1790 or 1970 respectively.
Ant
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
02-23-2010 12:17 AM  10 years ago
ivorz

rrNovice

Heli Wonderland

MyPosts All Forum Topic
I am using a 13T pin, 6s 3000maH 25C, 1700kv motor.
So are you saying I should drop to an 11T pinion.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
02-24-2010 03:01 PM  10 years ago
Antsis

rrApprentice

, Australia

MyPosts All Forum Topic
With that setup, dropping to an 11T will probably lower you HS to around 2200-2300 rpm. I would then play with the throttle curve and drop the HS until the model starts nodding (HS is getting too low). Then play with the curve to bring increase the HS to stop nodding.

It's a question of trial and error. You change the pinion to reduce the HS, but keep the motor running in the correct efficiency range and then play with your curves to get the best compromise. You may still end up with a high HS, which does not look nice, but you will have a comfortable flying model.
Ant
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
WATCH
 1 page 901 views Post Reply
HomeScale✈️AircraftScale HeliScale Helicopter Main Discussion › MD 500 Vibrations
Print TOPIC

 2  Topic Subscribe

Saturday, November 28 - 1:14 am - Copyright © 2000-2020 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online