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Bell 47 Crash

Old 01-04-2010, 11:19 AM
  #26  
pa18135
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Default RE: Bell 47 Crash

HAPPY 2010 to you too Lawrence Claude
Old 03-08-2010, 07:56 AM
  #27  
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Default RE: Bell 47 Crash

Hi All,

I just came back from Malaysia for my annual leave. the first thing i did last weekend was taking out my hirobo and tested my home made blade.

few observations:

(1) Engine started ok, but it has sudden jerks (sounds like back fire?) for interval around 5-10 seconds and continuously.
(2) I set low needle valve to 1.25 truns and high 1.5 turns for the hirobo 20cc engine (as with the manual says), the heli tens to lift at about 95% throttle but with a strong yaw to left although i put on full right throttle.

I stopped the engine, adjusted the pitch to less travel and adjusted throttle linkage to allow bigger operating envelope

(3) heli stuggle to lift but tail9ruddr0 is now more controlable.

As my blade is made to 805 mm, the uneven jerks make the tail blade and main blade tilt and hit each other, nothing too serious but a linkage at tail is broken.

then i also realise that the METAL piece holding the stabilizers ( and connecte to main axis) has a broken piece near to he part which hold the bearing. []

I have came back, cut the blades to 800 mm now so that they wont touch the tail blades, I managed to repair the tail piece but still thinking of a solution for the metal head part. any idea folks? I will try to take a picture and show you guys here.

since it is the older version, i think i wont be able to find a replacement part. also, it is quite different from the newer head design so dont think i cna find a direct replacement alternative. find a way to repair it securely or reproduce a piece? but i dont have the tools to deal with metal blocks!!

btw, could anyone pleas poste a picture showing the head of the newer gasser bell 47G here? then i will see if i can use the newer parts to modify..


many thanks.

also folks, i tuned the engine but dont hear a high pitch when i throttle up, should i retune or it is gas engine characteristic that is different from nitro engine?

anyone know of the jerks from my engine is an indication of too rich or fuel starving/

thanks.

Lawrence
Old 03-15-2010, 04:00 AM
  #28  
lawrencelkl
 
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Default RE: Bell 47 Crash

Hi Claude and yacsf,

I have got my hirobo bell 47 G test flown for the first time!! I was so excited and it can hover !

I have uploaded the video at this

http://www.youtube.com/watch?v=4J57qiOQzdA

I feel great because of few points:
(1) I have heard people saying the older hirobo engine (20c.c.) is underpowered even to hover, but at least it was fine yesterday!
(2) It flown with my first hand made wooden blades! I have been sanding a lot in order to get the blade sanded to shape, balanced and reinforced.it works! It is the test pair, I might get a carbon pair in some times when i saved enough...
(3) Of course, this is my first gasser. it has been on display only by previous owner so I feel really good to let her in air!
(4) great help from people on the forum, well done foks!


Lawrence
Old 03-16-2010, 04:43 AM
  #29  
lawrencelkl
 
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Default RE: Bell 47 Crash

Hi Claude,

May I know what servos do you have on your bell 47G? Will standard servo works well with this heli or has to be some stronger servo? if so, what are the criteria? i.e. torque rating etc. thanks.

Lawrence
Old 03-16-2010, 02:52 PM
  #30  
pa18135
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Default RE: Bell 47 Crash

Hi Lawrence,on my Bell 47 I have FUTABA SERVO for the SWASH PLATE and PITCH # S9202 for my tail rotor S9254 for the throttle S3151.Hoping this will help you. Claude
Old 03-22-2010, 08:47 AM
  #31  
lawrencelkl
 
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Default RE: Bell 47 Crash

Hi all,

some updates about the hirobo bell 47G.

Thanks for the info about servo, Claude.

I managed to bring the hirobo to the field yesterday. it flew for the first flight but the main mast stopper slipped and I had to come back to fix it.[]

Although it was jsut one flight, i can notice that the engine did starts ok. but does not iddle that well when the choke is fully open. it is too rich or lean? if i start with choke half closed, then it start ok, then i slowly open the choke and increasing throttle slowly, then it will fly well.

i did the flight with a longer set of tail blades, around 143cm and i can see that it is much better than previous 130 cm tail blades.

cheers.

Lawrence
Old 05-04-2010, 06:35 AM
  #32  
lawrencelkl
 
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Default RE: Bell 47 Crash

Hi All,

Managed to bring my bell 47G to the field yesterday. BUT there were a lot of glitches/radio interference. all is fine when i tested with the engine off. All is also fine when the engine is idle or up to 50% throttle, but at soon as it is about 75%, I cna see the swatch and pitch servo glitches and moving up and down it self. when I pulled the throttle back, then the glitchess go away.

May I know what I need to do to resolve this? will 2.4GHz be the solution to eliminate all glitches in gasser?

Thanks a lot. Also, after the glitches, my pitch servo gone dead.[]

I might want to get better quality servos to get replacement of the current normal servos, installed for test flight.

thanks.

Lawrence
Old 05-05-2010, 02:05 AM
  #33  
yacsf
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Default RE: Bell 47 Crash

Use this sparkplug NGK BPMR7A for this Tanaka 24cc engine. No giltches of servos.
Old 05-05-2010, 02:24 AM
  #34  
lawrencelkl
 
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Default RE: Bell 47 Crash

Hi Yacsf,
Thanks for your reply, I am using the older Hirobo HGE-20EH engine. Do you know if the NGK BPMR7A will fit as well? I will try to do that at first trial before investing in other more expensive stuff.

Many thanks.
Lawrence
Old 05-05-2010, 05:24 AM
  #35  
yacsf
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Default RE: Bell 47 Crash

Here is the chart for u to check;

http://www.spark-plugs.co.uk/pages/technical/ngkjpg.htm
Old 05-05-2010, 06:09 AM
  #36  
lawrencelkl
 
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Default RE: Bell 47 Crash

Hi yacsf,

Thanks a lot, I have ordered one spark plug and it is on its way! will test and report the updates here.

Cheers

Lawrence
Old 06-02-2010, 03:24 AM
  #37  
lawrencelkl
 
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Default RE: Bell 47 Crash

Hi folks,

latest updates about my old hirobo bell 47G. I have it tested again few days ago. This time, it was really struggling to lift.

May I know what pitch range do you guys use for this heli? I am using the home made 800 MM wooden blade.

Anyone familiar with petrol carburetor please help me here

Symptom:

about 1 1/8 turns on the low neddle valve, about 1 1/4 on the high.
I closed the choke, pulled 2-3 times, and open the choke about 20% then it will start. but it does not idle well and will die soon. I have to quickly throttle up in order to keep it running.

I also tried to fully open choke and start and it wont start!

am i running too rich? lean ? it is ok to run the engine at 25% choke opening and advance throttle to full for flight?

if i further increase the pitch of the blades, then the engine sounds rough and slow at higher throttle, does it mean the engine is not powerful enough?

it seems like a really tight thottle envelope where i manage to lift the heli but jsut 1 ft or so off ground, no spare power at all.


all helps highly appreciated!

Lawrence
Old 06-02-2010, 04:58 AM
  #38  
glenladen
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Default RE: Bell 47 Crash

G'day Lawerence,who made the carby on your engine?,it sounds like you may have a partially blocked filter in the carby which will affect your engine regardless of throttle setting also did you get an operators manual for your engine as it will explain how to service your carby.
How's your fuel mix?,if petrol sits unused for awhile it will go off-still useable if you have a lawn mower tho' just doesn't let the engine run to reliably.

Has your engine done alot of work?, if so,it may need a new piston and rings and liner.Servicing both the carby and engine is fairly simple and easy to do,fitting the rings onto the piston is a pain tho' unless you can get the piston with them already fitted.

Hope you get it sorted,I never was in a position to get the early hirobo version of the B47,but Iam a proud owner of the mk2 version.

cheers,
Glenn.
Old 06-02-2010, 06:51 AM
  #39  
lawrencelkl
 
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Default RE: Bell 47 Crash

Hello Glenn,

Thank you very much for your quick response and advices. The carby is made by wallbro. when I purchased this gasser with the engine, the engine did not start at all as it has been 20 + years. I found that the gasket and diaphram are all stiff. I managed to buy a new set and changed and since the engine runs.

It has been about few months since i changed the carby gasket etc but i had only run for around 30-60 minuts in total. but as you said, it might be partially blocked. I can open up the carby and try to clean it.

i think the petrol age might be another reason as well because i have it about 2 months now. maybe i will go and take some fresh petrol to try. also, can we leave fuel mixed with lubricant sitting there before next run or have to mix fresh batch everytime?

I have also ordered a wrench and will try to install a new spark plug as the one has been for 20+ eyars as well although the engine has never been run for long. previosu owner never run the engine, that is what i understood.

Thanks Glenn, can you psot some pic or video of you MK2 here?

Lawrence
Old 06-02-2010, 08:33 PM
  #40  
glenladen
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Default RE: Bell 47 Crash

G'day Lawrence,If you've been flying your B47 regulary(2month layoff is okay) then the diaphram and gasket should be okay,also check the exhaust outlet gasket if that blows
it can cause a few running problems.Usually a lot of exhaust residue gets sprayed over the model.

As long as the fuel is no more than a week or two old it should be fine,anything over that would be asking for murphy's law to kick in obviously the fresher the better.

Check your spark plug for oiling as that will affect the engines performance,wich means the mixture is too rich.
Walbro carby's are a good carby and used on alot of petrol engines and are easy to tune,just the two needles.

I'll chase up some pic's of mine,at the moment it's partially disassembled as I was messing around with the fuel lines and connected them up around the wrong way and not realizing it I glued the dummy fuel tank halves together.To cut a long storey short she wouldn't start and now I've got new dummy fuel tanks to fit.
I did test run prior to fitting the dummy's to make sure I'd got it right!.[:@]

cheers,
Glenn.
Old 06-03-2010, 03:41 AM
  #41  
lawrencelkl
 
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Default RE: Bell 47 Crash

Hi Glenn,

Thanks for your reply. I will check the carby and exhaust port tonight or tomorrow.
I have a 30 c.c. lawn mover engine which has wallbro carby as well . I might want to bring that to the field next time and see what this engine does with the carby.

will definitely post updates here once I have got a chance to try out.

good luck with your new dummy fitting!

cheers

Lawrence
Old 06-03-2010, 06:23 AM
  #42  
glenladen
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Default RE: Bell 47 Crash

G'day Lawrence,no worries.
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Old 06-03-2010, 07:38 AM
  #43  
lawrencelkl
 
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Default RE: Bell 47 Crash

Nice Heli Glenn,

which engine do you have in this heli? looks cool

Lawrence
Old 06-03-2010, 08:23 PM
  #44  
glenladen
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Default RE: Bell 47 Crash

G'day,Lawrence,thank's for the compliments.

The engine is a TAS 24cc 2stroke 25:1 fuel mix which is ideal for northwest western australia and my lawn mower takes the same fuel mix.It also use's the Walbro carby
and as Claude stated doesn't require an external ignition box and battery.

Cheers,
Glenn.
Old 06-07-2010, 07:29 AM
  #45  
lawrencelkl
 
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Default RE: Bell 47 Crash

Hi all,

some updates from me. the engine did not get to idle well and only run when the choke was partially opened, will die out immediately when choke fully open. Engine was stuggling to lift at all, and seems very hot.
as suggested by Glenn, i cleaned the carby and all changed. this is the video taken after the carby is cleanned.

Thanks a lot folks!

http://www.youtube.com/watch?v=q9MZr6MS4gg


Lawrence
Old 06-09-2010, 12:01 AM
  #46  
glenladen
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Default RE: Bell 47 Crash

G'day Lawrence,glad it's sorted i've just finished watching your vid and I'm really hanging out for daysoff to get mine out again.
cheers,
lenn.
Old 06-22-2010, 11:04 AM
  #47  
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Default RE: Bell 47 Crash

I have a Hirobo Bell 47 and the starter keeps breaking (The black plastic piece with the spring). Is there any upgrade or electric starter available for this model. I would sure appreciate some ideas that would keep this thing flying. It is a HUGE paperweight on my desk.
Old 06-22-2010, 06:10 PM
  #48  
glenladen
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Default RE: Bell 47 Crash

G'day Hagermeister,the only electric started that I know of is made by Vario for their modified Zenoahs and I don't know if they would fit without modification.
Is the part thats broken the cover which contains the spring? Hirobo should have it listed wih a part number,I don't know if there is an upgrade for this component.
Sorry for not being much help.
Glenn.
Old 07-05-2010, 10:17 AM
  #49  
lawrencelkl
 
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Default RE: Bell 47 Crash

Hello folks,

May I know if there is still place where I can buy the older version helical main gear? I noticed that the teeth started to show some signs, not sure it they were like this before or just due to the recent relatively short flights??!!

otherwise, not sure if the later straight gears will be a direct replacement? but then again, i have to change the pinion from clutch, main gear and the tail transmission gear...3 pieces...

anyone can make me a helical gear?

Cheers

Lawrence
Old 07-07-2010, 09:15 AM
  #50  
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Default RE: Bell 47 Crash

Thanks. I have a replacement part that came all together but you have to lockout the motor from turning somehow to turn off the nut holding the peice to the drive shaft. I hadn't figured that out yet but got tired of seeing the dust thicken on the canopy so I used a friends Sullivan Megatron starter to turn it without the recoil starter attached. it worked so I will just start it now with the megatron. I would love to start it by remote like the Vario as you stated. Maybe someday if I need a new motor. Thanks for the input.

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