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HomeAircraftHelicopterCentury Radikal G20-30 N640 Hawk Predator › Hawk Sport Fan problems?
11-05-2004 03:34 AM  13 years agoPost 1
rcsoar4fun

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Boise, Idaho

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As of yet I have not had any problems with the fan on my Hawk, except the thing coming loose. A buddy of mine has managed to destroy two fans on his, one lasted less than one flight. Is there any known problems with the fan setup?

Kristopher

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11-05-2004 03:41 AM  13 years agoPost 2
onebigjunker

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Wellsville, Ks

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have you tried lock tite on the blots mine stays on just fine so far

work hard, play even harder!!!!
Team Empire Hobby/GAUI USA

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11-05-2004 04:11 AM  13 years agoPost 3
SteveH

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Texas

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The problem with the fan coming off actually has nothing to do with the fan, but all to do with how the CLUTCH is installed. The fan is keyed to the clutch, and will not turn if the clutch does not turn on the crank shaft.

The clutch must be installed properly with Locktite, and tightened on the engine crank shaft while the crank shaft is held from turning using a crank locking divise. I use a special plastic crank lock and a spanner type wrench to tighten the clutches. After that, the engine shaft nut holds the fan onto the clutch with a little locktite, but it does not have to be especially tight.

The government cannot give you anything without first taking it from someone else.

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11-05-2004 05:54 AM  13 years agoPost 4
rcsoar4fun

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Boise, Idaho

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My friends fan broke where the starter shaft engages. It is possible there is a bent shaft, or can something else cause this?

Kristopher

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11-05-2004 12:05 PM  13 years agoPost 5
SteveH

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Texas

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Kristopher,

A broken fan at that location is usually caused by either trying to start the engine with a hycraulic lock, starting the starter before the dogbone is engaged, or the dogbone pin sliding to one side will also cause it. The earlier models used a roll pin in the dogbone and sometimes they would slide over, and in that case it should be slid back into place and red locktited.

The government cannot give you anything without first taking it from someone else.

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11-05-2004 01:14 PM  13 years agoPost 6
Duracizer

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NC

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. I use a special plastic crank lock and a spanner type wrench to tighten the clutches.
Here's a tip for those of us who don't have piston locks. Take out the glowplug and rotate the piston so that it's up past where the muffler bolts on. Then take a good length of string and feed it into the head through where the glowplug used to be. Keep feeding it until uyou can't get anymore in there, now as you tighten/loosen the clutch the piston will not be able to move (and this also will not cause any damage to the piston).

I saw some racing buddies using this trick on their gokarts so I tried it myself and it works great.

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11-05-2004 02:38 PM  13 years agoPost 7
Trace

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Wildwood, MO

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or the dogbone pin sliding to one side will also cause it.
SteveH is right on with this one and this can happen with the current version as well. If the pin slips to one side it tends to beat on the groove on one side until the fan fails. I had this happen, recentered the pin, loctited the set screw, got about 3 flights and broke another fan. Pulled the pin, filed a flat where the set screw contacts and loctited the set screw again. No way that sucker can move now.

I have a theory about why this happens to some and not others. Set the return spring on the dogbone such that it goes to the bottom of the slots, but does not completely bottom out when you press it all the way down. Now wiggle/rotate the start shaft like you would when checking gear mesh, rotate the fan 90 degrees and check it again. If the dogbone does not wiggle at both locations you need to break the engine mount or start shaft bearing holders loose and adjust everything until it does wiggle in the slot at all rotations. It's not critical how much it wiggles at each location, just as long as it does. Also, put a flat on the dog bone for the set screw like I mentioned above and it won't happen again.

Part of what I believe is happening, is if the shaft is not centered properly, it is loading up the shaft at one location in the rotation, usually on only one side of the pin. This causes a hammering vibration to the dog bone and against the fan, which in turn could make a dog bone migrate to one side, worsening the condition, and eventually leading to a fan failure. How quickly this happens is all a function of engine compression, starter speed and torque, starter shaft mis-alignment amount, whether or not you are using a one-way start wand, etc....

Whew, my fingers hurt, I'll shut up now. YMMV

Trace

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11-06-2004 12:55 AM  13 years agoPost 8
EeGadsMan

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Tulsa, Oklahoma

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Its me..
Ok, im registered and no longer a lurker...

Im the one with the *major* fan problems.
Im using an OS 50 SX engine, which I believe basically requires a little bit too much torque for the stock starting assemblies (the fan, in particular). Infact, the engine has so much compression when cold-starting (and sometimes even still after a few flights) that my hobby starter wont start it; it gets stuck. So, Ive had to resort to using a drill. This works, but Im careful about how I go about it.
Anyways, the drill has gearing, etc, within it that that when engaged upon the starter, it's going to take a LOT of force to stop it. When starting my engine, it does as most 2-stroke model engines do, and kicks (sometimes resulting in starting backwards) - and therein is where I think the problem is. This kick, combined with the drill's torque capabilities (even at low speeds) is simply more force than the plastic fan can take. Did I create this problem - or is it simply inhearant to using a 50 in a Hawk Sport 35 airframe?
The solution to this problem, I believe, is in purchasing and installing a machined metal "turbo" fan. The metal would surely be stronger than the stock plastic fan.

...I just wish those fans werent $40!!!

I think I have an alternative that will still allow me to use the cheaper plastic fans.. just need to put together the materials to create it. If anyone else cares to know about it, I'll post my results when I get it made (hopefully sometime this weekend.)

-EeGadsMan
Hawk Sport - OS 50SX, and LMH-117, HiTec Eclipse-7

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11-06-2004 02:28 AM  13 years agoPost 9
Duracizer

rrApprentice

NC

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I had the same problem with my O.S. 32 sometimes starting backwards from the kick. I fixed the problem by getting a starter shaft with a one way bearing in it. Now my engine never starts in reverse.....

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11-06-2004 03:06 PM  13 years agoPost 10
NewHeli

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Pittsburgh, Pennsylvania, USA

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I think I have a solution for the "destroyed" fans:
This is copied from one of my other posts:

Also, while you're at it, sand or file the edge of the fan notches that the starter insert DOES NOT press against. Now when the engine starts, the angle in the "trailing edge" of the fan notch will force the starter insert up and out of the fan so it won't break.

Sorry, I don't have a picture

NewHeli

Nathaniel Rice
Team YS Engines

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11-06-2004 06:32 PM  13 years agoPost 11
oldfart

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Vancouver, Canada

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starting and fan
EeGadsMan

I have been using the OS50SXH engine on my Falcon since the OS50SXH first came out. I have yet to replace a fan! Ditto for a number of others I know.

The plastic fan has more then enough strength to handle any 50 engine's starting requirements, if installed as described by SteveH, Durasizer and Trace.

Note: If you are starting the engine overly rich so that it requires a geared drill to turn it then that is where your problem lies - the geared drill is either not turning the engine fast enough or the engine IS TOO RICH and by using the metal fan and the drill to force the engine to turn, you will be risking damage to the con rod of the engine. IMHO it is better in this case to break a $5.50 plastic cooling (Who is charging you $40.00 for them ???) fan then damaging a $180.00 motor.

PLEASE DO NOT USE A GEARED DRILL OR ANY OTHER DRILL to start any heli motor. Unlike airplanes, heli motors do not have props on them that can act as levered flywheels to help with the starting. They require a starter that can turn them at an appropriate speed in order to start properly.

Of note is that if you are overly rich and your engine is backfiring enough to loosen the clutch and prop nut or break your fans, then a one-way start wand such as the CN0427 will help here.

Phil

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06-21-2005 07:34 PM  13 years agoPost 12
EeGadsMan

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Tulsa, Oklahoma

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Just fyi to all.. I ramped the notches with a dremel, so that if it starts it kicks the starter shaft out of the notch.. and I have yet to break another fan.. been flying with this one now since the idea was suggested in here. So, my suggestion, is that if you have a fan breakage problem, simply remove the unused side (back) of the starter notch in the fan; make it a smooth ramp up to the rest of the flange, and if the engine starts or kicks really hard, as aparently mine was, it wont break the fan. Instead, it will kick the starter shaft out of the grove smoothly, and all is well :-) Thanks for everyone's help! Btw, I have pics of my Hawk that was having all these problems.. Isnt she pretty?? heheh

http://pg.photos.yahoo.com/ph/eegad...dsman/my_photos

-EeGadsMan

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06-22-2005 11:33 PM  13 years agoPost 13
BC Don

rrElite Veteran

Calgary, AB Canada

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I'm one of those guys who went through fans. My starter was powered by 2 * 7 cell batteries (16.8 v) so there was not problem turning over the engine at high speed.

I went to purple bling fans in both my Hawk and Raven. I then also went to a 1-way starter shaft. I don't know whether the 1-way solved my problems or not as I've changed to the purple bling. But, I don't have any problems any more.

Got Money? Send it to me, I'm a Heli Addict.

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06-23-2005 12:22 AM  13 years agoPost 14
oldfart

rrProfessor

Vancouver, Canada

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Don,

The one way shaft protects the fan from any backfire that results from starting when overly rich, just as the relief on the back side of the fan slot would do.

I literally have a couple thousand starts over the years on these fans on 50 size machines and never broke one fan - but I always used a one -way start shaft.

Phil

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06-23-2005 12:39 AM  13 years agoPost 15
AGRAV8

rrProfessor

Mosquito Coast......Houston Texas

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EeGadsMan
your heli looks GREAT to me !

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06-23-2005 01:00 AM  13 years agoPost 16
NewHeli

rrKey Veteran

Pittsburgh, Pennsylvania, USA

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Where are the pictures of his heli? I'd like to see how he fit a 50 in it

NewHeli

Nathaniel Rice
Team YS Engines

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06-24-2005 04:42 PM  13 years agoPost 17
EeGadsMan

rrNovice

Tulsa, Oklahoma

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Follow the link :-)

http://pg.photos.yahoo.com/ph/eegad...dsman/my_photos

Putting a 50 in the Hawk sport is easy; it's a different engine mount (the .46 mount fits the .50) and you need to change the speed-up gear (or whatever it's technically called).. but that's it.. works great, and a MAJOR performance boost!

-Ee

-EeGadsMan

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06-24-2005 05:20 PM  13 years agoPost 18
NewHeli

rrKey Veteran

Pittsburgh, Pennsylvania, USA

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Nice heli, but I'd like to see inside the fuselage, to see how the engine is mounted.

So all you need is a new engine mount and the speed-up gear? What about longer tailboom and 600mm blades? Or would a lower headspeed with the 550s work?

NewHeli

Nathaniel Rice
Team YS Engines

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