10S too much MOJO... stripped RevCo gear

[ukgroucho]

My Hurricane had it's first unplanned landing today :(

First flight of the day and I was really throwing it around... just came out of a funnel (of sorts) upright again as it was 'lacking power' and suddenly lost HS big time - like the motor shut down. Forty of fifty feet up, some distance away and I 'freeze'.. well I actually did exactly the WRONG thing and added +ve 'cos the heli was dropping and I had not told it to. I did not know if the motor was running or what. By the time I thought "I need to auto" and started trying to do it the 550 was down in the long grass.

... and the culprit - completely stripped main gear, every tooth gone. I know that I hit throttle hold before it went in. However, the flight data recorder data also confirms that the motor was suddenly unloaded but spinning full bore during the last seconds of the flight. This followed a sustained period of high amps and a "big" burst up to 65 amps - which seems to have been too much for the main gear to cope with.... I'm running all RevCo stuff here except the one way gear.

Damage?
Not too bad based on initial inspection.
- LG (replaced so I can get it on it's feet to work on it)
- FS (VERY slight but it's coming out later)
- one 500 CF blade.. I have another set

- one K&B "stiffie" tail blade - I have another set.
- bent flybar. Not bad. Will try to straighten as it's a Rappie 30 one and I only have Hurricane spares.
- Main and tail spindles? Not sure. I'll probably change them for the experience.

Oh well .. the CF frame is undamaged.
I think I might need to back off the throttle a bit...seems that 2Kw thru these gears is too much for them.

[Kepler]

Bad luck on that one ukg,

Suppose you cant be too disapointed when pushing out that sort of power. At least you know where the limits are now. 2000 watts must be insane power as the model will 3D on half that power.

[ukgroucho]

... and it looks liek one of the 5S packs died in the crash. Very little visible damage but cell 2 shows only 0.2 volts... :(
Bo!!o£

Oh.. FS was a little bent , main shaft was definitely bent.

[ukgroucho]

... OMG things do come in threes.
Took the Hurri for a test today. Took off and hovered nice, a few slow piros etc. to check out everything... imcrease power and head off and it dies on me again. This time I managed a fumbled auto into long grass. Still broke a LG leg and tail fin but seems OK apart fromt that.

My initial thought was I ripped another main gear apart (which would have really disturbed me) so I was 'pleased' to discover that the one way bearing had died. Not sure if I did sommat stupid with it when I fitted the new main gear.

[ukgroucho]

... or fours.

Stripped another RevCo front gear today. I was pushing really hard and this time it was 100 feet or more up and a long way off. I have to get my auto 'routine' sorted. Lots more damage this time :(

[Happy|Harry]

... or fours.

Stripped another RevCo front gear today. I was pushing really hard and this time it was 100 feet or more up and a long way off. I have to get my auto 'routine' sorted. Lots more damage this time :(

ouch i'm sorry to hear that buddy :(, maybe it's time to try the Gaui "OK" gears, or the new HeliDirect gears instead of the revco's?

phil

[mjdee14]

ouch i'm sorry to hear that buddy :(, maybe it's time to try the Gaui "OK" gears, or the new HeliDirect gears instead of the revco's?

phil

If the Revco's won't take it the OK 's would never make it....don't know about the heli direct.

I'm not sure anything short of steel on steel could take the power he is putting out with 10s packs...!!

ukg....you are an Animal ..lol Post some vids...would love to see 10s fling on this heli....must be Faaast !

[Happy|Harry]

If the Revco's won't take it the OK 's would never make it....don't know about the heli direct.

I'm not sure anything short of steel on steel could take the power he is putting out with 10s packs...!!

ukg....you are an Animal ..lol Post some vids...would love to see 10s fling on this heli....must be Faaast !

10S makes no difference as watts are watts ;) weather it's 6S or 10S the gearing doesn't know ;)

also tom viper has had great success with the OK high power gears so don't discount them that easily :)

phil

[mjdee14]

10S
also tom viper has had great success with the OK high power gears so don't discount them that easily :)

phil

I'm happy to hear the Ok gears are pretty good, i thought they were just marginally better than what they first had.

Is there a limit on power input (watts) for these types of setups?

Seems a lot of people have been stripping gears with much less power, I understand that improper gear lash will greatly contribute to the problem.

[Kepler]

I think from memory ukgroucho needs the revco gears to get the correct gear ratio running 10S and an 800kv motor

[ukgroucho]

Yeah.. I cannot get the gearing low enough on OK gears to give a reasonable HS. Even with the lowest RevCo pinion I still have to drop the throttle for the governor (Kontronik Jazz) to a pretty low level (6x%) to get 2200 - 2300.

Bottom line is that if you push hard it will deliver up towards 2000 watts... when it stripped I was doing a tight funnel up high. FDR data shows >1900 watts / 62 amps.

Either I'm completely off base on the way I set the pinion mesh or I'm just expecting too much from mod 0.6 gears... My suspicion is that the gears overheat and soften under duress... and then it's game over.

Right now I don't have a plan to solve this.. fly a little less agressive and learn to auto properly is all I can come up with.

Merry Christmas / Happy Holidays

UKG

[ukgroucho]

... unless someone can suggest a supplier for an alu or brass gear.. I can stomach replacing every 20 - 30 flights if I KNOW that's what I have to do...

[mbigby]

The new T-Rex has .6M pinions with gears from 11T to 17T (supposedly). I eyeballed my kit and it would appear that the shaft diameter is 5mm. This may be your option: get a T-Rex 500 gear at 16T or 17T. Or maybe the revco guy is listening and will make 16T and 17T.

That being said, I wonder if a Kontronik Tango 600kv or 700kv wouldn't be a better setup for 10S?

[Mikej]

UKG - have you tried the Delrin ones that Microheli sell ? I've no idea if they are better or not, just thought that I'd mention them in case they help http://www.microheli.com/mhshop/index.php?cPath=107&osCsid=dc2bca03dc633a32574b082940c923ce

Cheers,
Mike.

[Happy|Harry]

ukg with the 42T primary, 61T secondary, 19T oneway and either a 13T or 14T pinion you should get round about the headspeed your looking for?

also sdp-si have mod0.8 pinions with setscrews for a 5mm shaft in sizes from 12T to 40T, and on up from there too lol :D, unfortunately they don't have any at all in mod0.6 :(

phil

[ukgroucho]

Interesting options folks. Thanks for the thoughts.

Not sure that the micro heli one is worth bothering with... I need to revisit the whole gearing thing. Rebuild is under way...

[mbigby]

Interestingly enough, ReadyHeli is showing 50T and 60T Gaui front gears. 50T:13T give a ratio of ~3.85:1. Your current setup, 68T:18T gives 3.78:1. Or you could do 60T:15T for 4:1. These might make your setup a little more efficient...

The open question is can the gaui gear material handle the wattage? Here's the ReadyHeli link:

http://www.readyheli.com/204621_Front_Main_Gear_50T_Gaui_Hurricane_550_p/204621.htm

- Mike

[istandalone]

and what are these "ok" gears? the gears that came with my 550 have OK stamped in white ink on them. are "ok" gears just a new material then the original gaui gears?

[Mikej]

and what are these "ok" gears? the gears that came with my 550 have OK stamped in white ink on them. are "ok" gears just a new material then the original gaui gears?

Yes:thumbup:

[Happy|Harry]

Interestingly enough, ReadyHeli is showing 50T and 60T Gaui front gears. 50T:13T give a ratio of ~3.85:1. Your current setup, 68T:18T gives 3.78:1. Or you could do 60T:15T for 4:1. These might make your setup a little more efficient...

The open question is can the gaui gear material handle the wattage? Here's the ReadyHeli link:

http://www.readyheli.com/204621_Front_Main_Gear_50T_Gaui_Hurricane_550_p/204621.htm

- Mike

sweet :cool: those are definitely new, and certainly open up the gearing choices and with that the motor choices too!

thanks for the heads up mike :cool:

phil

[Mikej]

UKG - help may be at hand from Helidirect - from RCGroups 550 thread

Helidirect says "Also Charley is designing a total new frame to eliminate the front gear system of the original Gaui Hurricane 550 so there is no more front gear stripping problem. This new frame will use similar gear system as T-REX 450 with main gear and tail drive gear only. This will eliminate 100% all problems of the stock frame. They will also include all features of the FCS frame of Rotorworkz above."

This here http://www.rcgroups.com/forums/showpost.php?p=8806111&postcount=2406

plus new frame here http://www.rcgroups.com/forums/showpost.php?p=8806128&postcount=2407

I hope that I haven't broken any forum rules by referencing another forum - if so apologies and please remove this post.

Cheers,
Mike.

[ukgroucho]

Mikej.... a couple of great ideas to go at there.

The new 50t gear looks promising. This will be mod 0.8 I expect so it should help a little. I'll certainly take a look at that... Moving from 3.78 to 4 to 1 might also help. I'll definitely take a look at that but the gears are out of stock right now (DUH!)

I had seen the reference to the new frame. I looked at Charleys first frame offering for the 550 as I really like his frames - I have two Trex 450 G4s and a G3 - but the battery options would not work for my two 5S packs. If the new frame has better options for me then I'll also look at that. However, I have quite a bit sunk into spares for the Gaui CF frame so I'm not going to rush that.

Thanks for the thoughts on this.

UKG

[ukgroucho]

So I'm now convinced that 0.6M gears cannot handle 10S. This is no reflection on the RevCo gears... I just think the teeth are too small.
So as you can guess I stripped another set today (3rd set)... second flight in cool conditions. First flight was 'gentle' (running packs in), second flight I was having fun and it ripped the main gear (first gear) again...

The really crappy aspect was that we've had a lot of rain here, horrible weather the last couple of days, but today was really quite nice for winter (sunny, 8 mph wind, 6 - 8C - say low to mid 40s Farenheit).
Anyway WET... so the 550 went in into a swamp that has developed off the end of our runway... 4 to 6 inches of water. When I got to it the heli was sitting in 4 or 5 inches of water. Good news is I got it upright in the way down - blades are fine (fore and aft), bad news is it came down hard enough to snap the (flimsy) Gaui LG so it sat nice and low in the water. Will have to see if the expensive electronic bits survived :( They are drying out on the heated floor of my bathroom right now (the whole heli is in there).

I'm done with the RevCo gears for now. Nicely made but not up to 10S ... 0.6 mod is really on the edge with this amount of power from what I can see so this is not a slur on RevCo. If they made bigger 0.8M gears (like the new Gaui gears) I'd buy them but it's too late for that as I've got some Gaui 0.8 mod stuff coming from ReadyHeli.

This crash is gonna need a serious rebuild as it smashed a servo case and busted one of the top CF side plates... gonna be grounded for a bit.

[Wazzer]

Hey UKG your really not having much luck with these gear sets are you!!
you should try lookinginto guys who build the big ride on steam trains they often have to make thier own gears sets for those, you might find a guy who would duplicate one of your gears in steel.

Where abouts in Stratford upon Avon do you Fly? I'm originally from Cheltenham, not far away. I used to come over to Stratford to go to the Long Marston Drag strip or Shakespear County Raceway or Avon Park or what ever new name they want to give it!!

Anyway just a thought

Ben

[Wazzer]

Hey Groucho

By coincidence i just came accross this webiste http://www.sdp-si.com/

check them out they seem to offer custom machining of gearsets and seem to be happy to do very small batches or one off's

Just a thought

Ben