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Old Nov 23, 2009, 05:44 PM
Team Wack-a-Mole
Melnic's Avatar
Maryland
Joined Oct 2008
8,439 Posts
Your fighting slop in the tail and servo resolution: Some things that got my EXI 250 to hold better:
1) smaller tail blades (as you saw), More tail slider movement required but this hides slop
2) align tail slider, HK250/Skya/EXI tail slider plastic ball is too small and adds slop to the control arm
3) Align tail control arm. The HK250 arm is too short on the tail linkage side which makes the tail slider move too much with the tail linkage movement. Align arm is longer and helps hide tail linkage and servo slop.
4) Good strong and fast digital tail servo and gyro
5) silicone glue the gyro plate to the frame if it's able to wiggle in place.
6) chinese weight mod on tail blade grips. Mostly on the outside as on the inside will hit the mechanics.

ANY of these mods become noticable.
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Old Nov 23, 2009, 09:35 PM
Registered User
Smyrna, TN
Joined Jan 2005
339 Posts
Any body using the fibergalss blades from Xheli? I got two pair of them, but I wanted to get some feedback. at 4000 rpm I would hate to have a blade break at the root.

Dave
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Old Nov 24, 2009, 03:19 AM
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UK
Joined May 2007
3,204 Posts
Quote:
Originally Posted by Melnic View Post
Your fighting slop in the tail and servo resolution: Some things that got my EXI 250 to hold better:
1) smaller tail blades (as you saw), More tail slider movement required but this hides slop
2) align tail slider, HK250/Skya/EXI tail slider plastic ball is too small and adds slop to the control arm
3) Align tail control arm. The HK250 arm is too short on the tail linkage side which makes the tail slider move too much with the tail linkage movement. Align arm is longer and helps hide tail linkage and servo slop.
4) Good strong and fast digital tail servo and gyro
5) silicone glue the gyro plate to the frame if it's able to wiggle in place.
6) chinese weight mod on tail blade grips. Mostly on the outside as on the inside will hit the mechanics.

ANY of these mods become noticable.
Thanks. Nice summary

BTW Would Align's DS-520 + Gy401 do? I'm going to strip them off my Protos (it can work with old s9650 on the tail and Ds-520 is a bit smaller )

Anyway - before I forgot to tighten up tail control arm so loop lost the ball and I lost control over tail... but just before all of it - I in-lined loop on control arm with piece of plastic bag (and use soldering iron to weld around the loop) and slop around the ball almost disappeared. But I am not sure if that would be the permanent solution. I have, in the mean time, bought align's metal control arm and will buy tail slider too...
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Old Nov 24, 2009, 12:21 PM
I Can Fly An FP Inverted!
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Teddington, Middlesex, UK
Joined Jun 2008
1,536 Posts
Quote:
Originally Posted by DESIGN ENGNR View Post
Any body using the fibergalss blades from Xheli? I got two pair of them, but I wanted to get some feedback. at 4000 rpm I would hate to have a blade break at the root.

Dave
fiberglass blades are way too heavy, they will never take 4000 rpm, nor will any feathering shaft/bearings/blade grip screws
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Old Nov 24, 2009, 02:51 PM
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Dark-Angel's Avatar
Canada, Quebec, Saguenay
Joined Jul 2008
540 Posts
got my lipo packs and some tg9 servos for the cyclic.

i was not so sure anymore about the 4s setup, but with the new packs installed, ive no doubt now that im builing the heli as a 4s setup.
canopy fit well too w/ the lipos...

next HK order will be a turnigy plush 12a esc that support 4s when they come back in stock
ive couple of rx's and gyro's laying around but im not sure i want to use any of the gyro i have atm(telebee, mystery, etc)

now just need to figure what motor to get for that 4s setup.
ive not found much suitable motor on HK yet, but maybe ill get one or 2 to test. till i find something better.

ive also got a ubec just incase the 2a bec on the plush become too hot.

the dual 2s pack weight 69g and they have very long wires which will be shortened eventualy

here some pics of my 4s mock up
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Old Nov 24, 2009, 05:37 PM
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Smyrna, TN
Joined Jan 2005
339 Posts
Hal,
The fiberglass blades I got are actually about 6 grams lighter than the stock plastic blades. I have done a few trim hovers sofar and they seem much better than the stock blades (track better too). I may add a little thin CA to the holes in the root just to strengthen them up a bit, but so far so good. Anybody else out there actually try these blades instead of assumptions?

Dave
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Old Nov 24, 2009, 05:40 PM
I Can Fly An FP Inverted!
Hal_The_Hacker's Avatar
Teddington, Middlesex, UK
Joined Jun 2008
1,536 Posts
Quote:
Originally Posted by DESIGN ENGNR View Post
Hal,
The fiberglass blades I got are actually about 6 grams lighter than the stock plastic blades. I have done a few trim hovers sofar and they seem much better than the stock blades (track better too). I may add a little thin CA to the holes in the root just to strengthen them up a bit, but so far so good. Anybody else out there actually try these blades instead of assumptions?

Dave
yes they are lighter than the stock plastics

just like everything else on the market


you run those FG blades at 4000 rpm and your heli wont last one pack, no assuming, happened to a guy with a GENUINE t rex 250 over on a german forum.

they are not designed for high headspeed like the carbons
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Old Nov 24, 2009, 06:00 PM
Skint since 2000
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Reading, United Kingdom
Joined Oct 2008
1,497 Posts
Quote:
Originally Posted by Dark-Angel View Post
got my lipo packs and some tg9 servos for the cyclic.

i was not so sure anymore about the 4s setup, but with the new packs installed, ive no doubt now that im builing the heli as a 4s setup.
canopy fit well too w/ the lipos...

next HK order will be a turnigy plush 12a esc that support 4s when they come back in stock
ive couple of rx's and gyro's laying around but im not sure i want to use any of the gyro i have atm(telebee, mystery, etc)

now just need to figure what motor to get for that 4s setup.
ive not found much suitable motor on HK yet, but maybe ill get one or 2 to test. till i find something better.

ive also got a ubec just incase the 2a bec on the plush become too hot.

the dual 2s pack weight 69g and they have very long wires which will be shortened eventualy

here some pics of my 4s mock up
Please get a video of when the head explodes on 4s
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Old Nov 24, 2009, 06:55 PM
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whopper's Avatar
Australia, QLD, Forest Lake
Joined Dec 2003
516 Posts
Why would the head explode running 4s? You would run a lower kV motor to achieve the same headspeed as a 3s setup. 4s just means lower current draw to achieve the same input wattage, hence better efficency........
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Old Nov 24, 2009, 10:11 PM
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Smyrna, TN
Joined Jan 2005
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3 packs in on the Fiber blades. So far no kaboom.

Dave
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Old Nov 25, 2009, 10:42 AM
Skint since 2000
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Reading, United Kingdom
Joined Oct 2008
1,497 Posts
Quote:
Originally Posted by whopper View Post
Why would the head explode running 4s? You would run a lower kV motor to achieve the same headspeed as a 3s setup. 4s just means lower current draw to achieve the same input wattage, hence better efficency........
It would have to be a pretty low kv motor and small pinion, we'll see what happens anyway.
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Old Nov 25, 2009, 02:32 PM
Team Wack-a-Mole
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Maryland
Joined Oct 2008
8,439 Posts
Quote:
Originally Posted by DESIGN ENGNR View Post
Any body using the fibergalss blades from Xheli? I got two pair of them, but I wanted to get some feedback. at 4000 rpm I would hate to have a blade break at the root.

Dave

I did not hear anything when I tried it so, that is what I've used. I think I only have 20 flights or less on the 250, Bad weather or flying other helis has taken precedence over the 250.

So far, after the initial test hover, I put on the FG 205mm blades from Xheli and have only used those. I have the 205 CF they sell but have yet to put them on. The 205FG survived 2 crashes of tail belt failures before it broke. I am on my 2nd set of FG blades right now. I think I'm running around 4000-4500RPMS headspeed. I was running just under 4000 initially for the first 5 flights then upp'd the pinion. The higher headspeed just made it more aerobatic. Lower headspeed was fine for sport flying and basic forward flight though.
EXI 250 Flight Video 1 (4 min 54 sec)
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Last edited by Melnic; Nov 25, 2009 at 02:37 PM.
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Old Nov 25, 2009, 02:36 PM
Team Wack-a-Mole
Melnic's Avatar
Maryland
Joined Oct 2008
8,439 Posts
Quote:
Originally Posted by clicky View Post
Thanks. Nice summary

BTW Would Align's DS-520 + Gy401 do? I'm going to strip them off my Protos (it can work with old s9650 on the tail and Ds-520 is a bit smaller )

Anyway - before I forgot to tighten up tail control arm so loop lost the ball and I lost control over tail... but just before all of it - I in-lined loop on control arm with piece of plastic bag (and use soldering iron to weld around the loop) and slop around the ball almost disappeared. But I am not sure if that would be the permanent solution. I have, in the mean time, bought align's metal control arm and will buy tail slider too...
I've heard of people using larger gyros but you just don't want the gyro touching the fram, just the foam.
520 is pretty big servo but I recall the photos of the EXI 250 website had a large servo on the tail. Your adding more weight though.
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Old Nov 25, 2009, 02:49 PM
I Can Fly An FP Inverted!
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Teddington, Middlesex, UK
Joined Jun 2008
1,536 Posts
Quote:
Originally Posted by Melnic View Post
I did not hear anything when I tried it so, that is what I've used. I think I only have 20 flights or less on the 250, Bad weather or flying other helis has taken precedence over the 250.

So far, after the initial test hover, I put on the FG 205mm blades from Xheli and have only used those. I have the 205 CF they sell but have yet to put them on. The 205FG survived 2 crashes of tail belt failures before it broke. I am on my 2nd set of FG blades right now. I think I'm running around 4000-4500RPMS headspeed. I was running just under 4000 initially for the first 5 flights then upp'd the pinion. The higher headspeed just made it more aerobatic. Lower headspeed was fine for sport flying and basic forward flight though.
EXI 250 Flight Video 1 (4 min 54 sec)

you are running 3250RPM on your heli, not 4500 I used a well known audio tach and it is accurate to 10rpm, the reading was taken as an average over 20 seconds.
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Old Nov 25, 2009, 03:26 PM
Team Wack-a-Mole
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Maryland
Joined Oct 2008
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Hal, I will take your word that you are measuring it in a manor that you feel is accurate but it does not agree with what I measured with my optical tach. I don't know what your using but if you used the Audacity method, I have yet to get that to work for me by using my videos. It never agrees with my tach. My tach has always agreed with my Eagle tree.

I just looked back over my notes and here is what I had:
3800Kv Turnigy motor using 3S pack and 11T motor was used at the beginning of the video.
3800Kv Turnigy motor using 3S pack and 13T motor was used at the end of the video (You will see text on the screen indicating the switch to 13T so sample that part during the hover)

Motor calc shows RPM with 11T to be 3900-3600 (initial RPM, RPM towards the last 30% of pack)(120 gear, 11T, 3800Kv motor, 3S pack)
Motor calc shows RPM with 13T to be 4600-4200 (initial RPM, RPM towards the last 30% of the pack)
I recall around 4400-4500 RPMs on spool up using an optical tack on the ground when I tested the 13T in my back yard (not on video). I'll tach it again next time I fly it.
I believe I'm running 100% throttle curve in idle up and 100% from zero pitch on up in normal mode.

3250 RPMS just does not sound like it would be correct even with the 11T (unless I was not using a 100% throttle curve back then which was possible because that was one of the first flights I had it when I filmed it in my backyard).
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