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HelicopterHIROBOOther › Helping stabilize unstable blades in the Freya
06-06-2004 04:29 AM  13 years agoPost 61
kym

rrApprentice

Provo Utah

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I flipped the blade grips, and flew it all day today. I have to say, it is more pitch sensitive. I adjusted my pitch curves, and i like how the machine handles now. It seems more agile. As far as hovering goes, it hovers great but i thought it locked in a hover better with the blade grips flipped the other way. So did my friend who flies too. It still hovers great, very stable. I did notice that at low rpm's my blades seem to be out of track. Once i got it up to 1800, the blades seemed more in track. I wonder if it has something to do with my carbon extreme dampners? I don't see how you could get a boom strike by flipping the blade grips. Maybe that's just me, and my two cents.

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06-06-2004 06:58 AM  13 years agoPost 62
Ray Nemovi

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SAN DIEGO CA

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u sould not boom strike by flipping the grips over. May need to look deeper into what happened. u can also play with your flybar ratio to slow it down since it is more agile.

Ray N.

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06-06-2004 07:56 AM  13 years agoPost 63
I3DM

rrProfessor

Israel

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The reason for the boom strike is not the flip itself. it appers that because of the flip, the collective got too fast, and when poushing a hard collective input (negative) into backwards inverted, the machine would loose a lot of RPM because of the hard input. that is what caused the boom strike. and like i said, this is no collective management issue, as i do this manuver all the time.
it happend to me on the first flight with this mod, but i had then thought it was because i now had too much collective.

i hope you guys know i usually know what im doing, the mahcine handled great before that, and will handle great once more after i get her up again. im going back to stock config.

www.liorzahavi.com

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06-06-2004 06:01 PM  13 years agoPost 64
Harbinger

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alberta

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its called collective management rookie

if ya need a link for the definition pm me

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06-06-2004 06:11 PM  13 years agoPost 65
Ray Nemovi

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SAN DIEGO CA

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Obviously this mod is not for you. Many have tried this mod and I yet to hear any of them having a boom strikes. Both Augusto and I have been working on this issue and pushed the heli and the mod works great. some people don't like the quick cyclic and thats why they use a slower flybar ratio or they don't use the mod at all. As for the bogging, u need to check to see how much cyclic pitch your runnig specially in elevator in your case and add it up to your collective pitch. this could be the cause of your bogging. In any case, your gonna argue what we tell u as if you know everything like in every other post. But goodluck and hope all works out for you.

Ray N.

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06-06-2004 06:15 PM  13 years agoPost 66
cripskillz

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Paso Robles CA

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Yo Snizzler

Im gona do the tail boom flybar swap and see if my shizzel flys any better

Ill let ya know

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06-07-2004 03:18 AM  13 years agoPost 67
ZZ3Astro

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Panama City, Fl

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I3DM

Guess that thing isn't flying so perfect now is it? Hahahhaha

steve

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06-07-2004 07:43 AM  13 years agoPost 68
I3DM

rrProfessor

Israel

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RAY-DOG, i used the same flybar input \ servo ATV's as before the flip, should there be a change in cyclic pitch ??

ZZ3, glad you got a good laugh out of the whole thing. Unlike you, i am trying to source the problem (thats what you do when you EXPIRIMENT) instead of whining about the machine ! this is a whole new expiriment thats wasnt dewsigned by Hirobo so im not complaining one bit !

www.liorzahavi.com

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06-07-2004 03:06 PM  13 years agoPost 69
breedatrad

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NW PA

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Multiple Bogies!

I flew my X-Spec several times this weekend with the grips flipped and there's more than one thing going on here, guys.
The blades and grips are free to flap slightly due to play between the feathering bearings and spindle. This can be amplified even further by flying on a hot day which will expand the grips, loosening the bearing fit within them even further (and yes, I realize that there's an aluminum insert molded into the grips but, aluminum and plastic move with temperature changes faster/more than the steel bearings). The pivot point of this flapping is centered between the two BB's which means that as the blades cone with collective inputs, some additional pitch is being added through the effect of the (now) positive delta arrangement (approx an extra 1 Deg.). This was opposite before (stock, negative delta with trailing control arm) which meant that you LOST approx 1 Deg. of pitch as the blades coned.
Proof: When setting up my machine in the stock configuration, I noticed that to get the collective "balanced" (+11 to -11 Deg); center collective actually had to show -1 Deg on the pitch gauge. This is because the blades were hanging against their own weight and the bearing/spindle slop (mentioned above) biased the blades an extra -1 Deg. Lifting the blade slightly would actually show 0 Deg. Without this compensation, the machine's collective range would effectively be -10 to +12 Deg; a difference you could definitely feel in the air! On top of that, as the blades coned both positively and negatively, they were losing approx 1 Deg of pitch decreasing the effective range to + 10 to -10 Deg... Pretty normal, actually.
Now flip the grips: As the blades cone, they now GAIN and extra 1 Deg of pitch increasing your effective collective range to +12 to -12 Deg! AND, remember that -1 Deg of pitch compensation I had to make in the last paragraph? Well now it's positive which means that IF you're not figuring it into your set-up (and you set your collective range to +11 to -11 Deg); you're now set for +11 to -13 Deg of collective. There's your increased collective sensitivity and boom-strike!
The positive delta arrangement helps keep the blades from overtaking the inputs as the head teeters against the dampeners, but does nothing as the blades flap around on their own.
Do I like the "grip-flip"? Yes, I do. But it requires a slightly different set-up to achieve the potential gains.

Brian

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06-07-2004 03:37 PM  13 years agoPost 70
jdowns

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San Diego, CA

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Interesting.... very interesting....

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06-07-2004 03:42 PM  13 years agoPost 71
kym

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Provo Utah

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The blades and grips are free to flap slightly due to play between the feathering bearings and spindle. This can be amplified even further by flying on a hot day which will expand the grips, loosening the bearing fit within them
So how would i fix this problem

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06-07-2004 03:55 PM  13 years agoPost 72
I3DM

rrProfessor

Israel

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Brian, thats very interesting, but my results were somewhat different. i set the machine up for +-11 as i always do, and with the grips flipped, it felt like i had +12 to -10, as it would climb significantly faster right side up, like a rocket actually !
anyway i think im just going back to stock, i got some KO servos for collective coming anyway, i think thats all the collective power \ speed you need.
thanks.

www.liorzahavi.com

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06-07-2004 07:02 PM  13 years agoPost 73
Dirty

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Des Moines, Iowa, USA

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grip flip

I just flipped my grips a couple of weeks ago and here is what I noticed. Without any changes to the radio setup as far as max and min pitch goes there were huge changes in the amount of pitch actually being applied to the blades in flight.

I was running +11,-10 before with decent climbout, just where I like it. I then flipped the grips and maintained my +11,-10 pitch and look out! This thing climbed out WAY faster and actually bogged down my YS91 pretty hard. I now have my pitch backed down to about +9,-10 and it is MUCH better.

Also, my cyclics were much faster with the grip flip and I have backed my cyclic pitch down quite a bit.

Conclusion: The grip flip is the Shiznit, BUT unless you change your pitch amounts you may have WAY too much pitch (collective and cyclic). It's a trial and error thing. Don't just go out there and say "My collective is +11,-11 so everything is perfect" This will not work for all setups. You have to test the bird with each new setup.

IMO grip flip = Faster, quicker, smoother, flys the line.

Darren

P.S. My aluminum liner in the blade grips is getting chewed up by the bearings and the aluminum spacer. I think this is because the CarbonXtreme dampners are so hard that some of the dampening is actually getting translated to these parts.

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06-07-2004 07:31 PM  13 years agoPost 74
Ray Nemovi

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SAN DIEGO CA

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I have ran the metal blade grips for about a gallon now and this seems to work really good as well but it is harder on the bearings.

Ray N.

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06-07-2004 07:55 PM  13 years agoPost 75
Augusto

rrElite Veteran

US

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FOLLOW UP

Having been able to use the flipped grips to be able to use the blades I wanted I went back to see if I could fix the problem using the standard configuration.

The grip flip test told me that a large portion of the problem was related to the effects of the delta. Now the thing that bothered me is that in the past I had used the same type of blades in the standard configuration without out-of-tracking issues so I wanted to see if I could get them to work without having the flip the grips because not everyone will want to do the flip anyways.

Reading a past thread about the bladegrips being lose I though about what effect could that have and realized that the grips being lose could amplifiy the effect of a destabilizing delta and depending on the blade it could hit a mechanical resonating oscillation that would manifest itself as the out of tracking issue.

The play they described in that thread was pretty severe so I inspected the blade grips and even though the grips seemed to be ok I could tell there was a very little bit of play in the grips. Usually I wouldn't have bothered because it took quite a bit of testing to even detect it but I still wanted to test the concept.

Even though the play seemed to be insignificant I did what SAL suggested of dissasembling the bearings and reinstalling them using Green Loctite (thanks SAL :-) ) . The bearings not being too lose took quite a bit of work to extract but I was able to extract them by using the spindle in a rotational stirring motion with one hand while holding the bladegrip with the other to slowly get them to move towards the edge until I finally got them out.

I then proceeded to clean the inside and reinstall the bearings using green loctite between the the outter case of the bearing and the grip's bearing cavity. I let it cure overnight and tested it the next day.

The result were excellent. I was able to use the worst offending blades and they all tracked like glass. This seems to suggest that even though the grips seem to be ok there may be enough play in them to allow for the oscillation to start and even if you don't have out-of-tracking issues it's never bad to have a better system at work.

Regarding green loctite. The green loctite is designed to penetrate in between parts that are already installed. It wicks into the two parts so if the inside of the grip bearing case looks clean you may only need to extract the outer one and use a toothpick to drop some green loctite in between the inner bearing's outer case and the grip bearing cavity. Make sure you don't let loctite get inside the bearings for the obvious reasons. Also let it cure overnight or it won't be hard enough to be effective.

I wish I have had some maverik blades to test and see if even those tracked after that.

So now it's only a matter of me deciding weather "To flip or not to flip.. that's the question"

I'll keep one flipped and one standard until I decide what I like best as far as flying performance.

Augusto.

Avant Aurora Ultimate

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06-07-2004 08:01 PM  13 years agoPost 76
I3DM

rrProfessor

Israel

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Well after reading everyone's comments it does appear that the pitch changes dramatically after doing the grip flip. can anyone explain why +-11 would now seem to give 12 or 13 degrees while flying with the grips flipped ? this seems odd and dangerous as it is.

www.liorzahavi.com

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06-07-2004 08:48 PM  13 years agoPost 77
Kinger

rrElite Veteran

Granville, OH

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Augusto - Please don't ever stop flying Hirobo ships Your testing and sharing of the results for everyone is simply fantastic. I'm thinking of trying out the green loctite on my Evo bearings too just to see what happens with a set of blades that are a bit out of track on my machine.

Team Synergy

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06-07-2004 08:50 PM  13 years agoPost 78
white chocolate

rrKey Veteran

Baltimore, Md.

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grips

I thought it might be the grips too. So I bought brand new ones with the bearings allready in them. I put my mah back on and same thing. I have changed everything I can change. I give up. I have switched to the new v2 blades for now. They are hard and feel smooth at the same time. Maybe one day I will be able to fly the mah"s again!!! Keep trying Augusto!!

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06-07-2004 09:15 PM  13 years agoPost 79
breedatrad

rrApprentice

NW PA

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Well after reading everyone's comments it does appear that the pitch changes dramatically after doing the grip flip. can anyone explain why +-11 would now seem to give 12 or 13 degrees while flying with the grips flipped ?
I3DM,
I already did. Read my post again.

Brian

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06-07-2004 09:32 PM  13 years agoPost 80
kym

rrApprentice

Provo Utah

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Augusto, Thanks for the information. Great Work

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HelicopterHIROBOOther › Helping stabilize unstable blades in the Freya
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