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HomeScale✈️AircraftScale HeliScale Helicopter Main Discussion › Vario R22 Tail bob
07-26-2017 02:00 PM  4 years ago
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tow cobra

rrApprentice

Westhampton, NY

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Vario R22 Tail bob
Wanted to get advice on a vario R22.
I have a vario R22 that I converted to electric using 12 cells, cc160 and scorpion motor.

I am able to hover it but once I start to get up to about 10 feet, I notice that the tail bobs up and down at a relatively high frequency. Because of this, I am reluctant to push into forward flight until I have this resolved.

Helicopter has an original flybar head and original mechanic with the motor up front (obviously now electric).

My thoughts would be that this could be a head speed issue or I have an item out of balance but I'm not certain and would appreciate any advice to point me in the right direction to eliminate the tail bob.
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07-26-2017 06:48 PM  4 years ago
Phoenix NOTAR

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Tallahassee, Florida USA

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where is the CG (balance), lifting by the flybar when does the rear of the skids lift. And what is the rotor head speed?

Sandy
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07-26-2017 07:42 PM  4 years ago
tow cobra

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Westhampton, NY

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Rotor speed is 900

Will need to check CG this evening once home from work but will report.

I am using relatively heavy batteries (Thunderpower 6s 5000 x2) which may be throwing off CG.

I did think it could be a headspeed issue as I had a similar issue with my goblin 630 at low headspeed with DFC head when headspeed was below 2000 (A known issue with that headspeed).
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07-26-2017 07:55 PM  4 years ago
Phoenix NOTAR

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Tallahassee, Florida USA

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850-900 rpm is good on mine (fbl). Are you sure it is only 900?
Also check the O ring dampers in the head. It should feel very tight, almost no movement.

Sandy
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07-27-2017 12:10 AM  4 years ago
tow cobra

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Westhampton, NY

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RPM is 900 (just tacked it).

head dampers are very tight (no play)

CG is right at the main shaft.

I found blades slightly out of balance tonite so I balanced them which gave me very slight improvement in bob.

When I spool down, it looks to me like there is some play in the main shaft when looking from above (meaning it appears to have some movement rather than spinning perfectly without any lateral or fore/aft movement in the main shaft...it is slight but I think it's there.. maybe a machine this big moves a little out of balance compared to my smaller 3d helicopter when aren't spinning as much mass and don't seem to move around when spooling down when looking at the main shaft from above).

My other thought is that maybe my cyclic servos do not have enough torque. I am using DS8311. Maybe I need high torque servos to control the swash properly even though I am using the flybar head?
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07-27-2017 01:09 AM  4 years ago
tow cobra

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Westhampton, NY

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Also, although mainshaft looks to move around slightly when spooling down, there is no play in it up or down, side to side when I test it and try to move it.

Also, when spooling down without blades on, main shaft appears to spin true. Can't look from above when blades are on due to circumference of the blades preventing me from seeing from above.
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07-27-2017 11:06 AM  4 years ago
Notar (RIP)

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Taxachussetts

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Just dont pick the heli up by the rotorgrip, as it will bend the shaft.
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07-27-2017 12:18 PM  4 years ago
tow cobra

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Westhampton, NY

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Took off the fbl head and then ran motor and absolutely no vide and main shaft spins true so issue is likely in the fbl head.

I am very thinking of converting to fbl at this point.

Do they still make a conversion (i.e. I can keep the blade grips) or will I have to buy vario fbl head which I understand is quite expensive?
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07-27-2017 12:24 PM  4 years ago
Phoenix NOTAR

rrApprentice

Tallahassee, Florida USA

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I suggest making some trials with the blades at different levels of tightness in the grips. If nothing positive comes from that, check the balance of the head without the blades.

Can you make a short video of the issue in a hover?

Sandy
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07-27-2017 12:33 PM  4 years ago
JuanRodriguez

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The Villages, Florida

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Would also suggest trying a different set of blades if you have them....

Also, try bumping up or reducing your headspeed a bit to see if it has any effect.....

Do one thing at a time as you try to sort this out.
Been there, done that and old enough to know better.....
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07-27-2017 04:04 PM  4 years ago
Phoenix NOTAR

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Tallahassee, Florida USA

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Tow Cobra,

Any chance that you are coming to IRCHA. I could help you with it there, and I could also bring a new pair of Vario R22 glass blades. (I run Aluminum blades now)

I live in central PA, and I could help you with it there as well, as I am very familiar with the R22

Sandy
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07-27-2017 05:56 PM  4 years ago
tow cobra

rrApprentice

Westhampton, NY

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Thanks for the great advice guys.
Sandy, I will not be at IRCHA but appreciate the offer.

Juan, I will definitely consider getting a new set of blades.

So I pulled the head off and spooled up as I listed above and there is absolutely no vibe in the main shaft at 900rpm so I think it must be a problem with the head or the blades.

I decided to go flybarless so I ordered the head and other necessary parts this morning.

I ordered some savox high torque servos for the cyclic.

Will keep you informed once I get it together as I think this will solve the problems.
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09-10-2017 12:58 AM  4 years ago
tow cobra

rrApprentice

Westhampton, NY

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I recently completed my conversion of my R22 to flybarless. What a difference.

Absolutely no tail bob, no vibrations and it hovers and flies like a dream.

I am using a Bavarian Demon 3x with 4 savox digital servos on my swash.

I would definitely recommend that anyone considering the conversion to FBL for the R22 go ahead as it is certainly an improvement in my opinion (I imagine most of these are FBL at this point but if anyone who is still using a flybar and wanted to consider the conversion, I would recommend this).

Excited to fly this more.

Thanks for the help, guys.

Only point to note is that the flybar programming is a bit tricky as the link from the swash to the blade grips is directly below the blade grip (unlike many 2 blade setups where it would be at a right angle) so you have to take this into account when setting up your FBL unit but after that, it's pretty straight forward and flies like my other FLB helicopters.
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