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CarbonXtreme . Midland Helicopters . HeliProz

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Scale Model RC Helicopters > vario bell 412 turbine
 
 
cossi101
New Heliman
Location: Malta

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Hi Guys
I just made a test flight on my Bell 412, and the flight was Ok but i am not happy till the end i found out that the tail is a bi havey and it's a bit slages on the alerones. The exponential is 100%.Cause i like the modeles to fly in a more sencitive way.Is this model a bit slages on flying. I know that the helli is a bit havey.Thanks for your Help...?
11-07-2009 05:45 AM
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Mike Bilyk
Senior Heliman
Location: Rancho Cucamonga, CA

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100% expo??? hope thats not right, you would have next to no control.

you should use max of around 30% expo.

AMA # 617778
Team MasterCard
11-07-2009 06:36 AM
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cossi101
New Heliman
Location: Malta

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Hi
I use futaba radio 2.4Mhz 10ch. so can you tell me if i make it 30% on the sec stwich?
Charlie
11-07-2009 07:46 AM
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modtron
Veteran
Location: Oxford. UK

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The model does come out tail heavy and it takes a lot to balance it where it is good to fly.

I have my batteries right up in the nose, under the steel plate and still have about 1 1/2 pounds of lead under them.

You will never get this machine to respond fast - even by adding 100% expo - it's just not suited to that type of flying.

The slow ( 904rpm ) rotor speed and long blades will not react in a zippy manor. You need to get used to the feel of the heli as it is.

I can assure you it flys just fine as it is.

www.youtube.com/watch?v=lwQtIhZDjS4

modtron
oxford Uk
11-07-2009 10:28 AM
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cossi101
New Heliman
Location: Malta

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Hello modtron

Thanks very much for your help.I am going to start from the CG. And then i thing i need to put up the rpm of the turbine cause it is 850rpm.cause it look's like it need's more head speed. I have to wait for next week cause the weather is bad. The wind is forces 5 to 6 to much to set the model. today i did 3 flight in that weather and i am geting use to it. so if you can keep in touch i will be very happy.Thanks
Best regard
Charles
11-07-2009 04:01 PM
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modtron
Veteran
Location: Oxford. UK

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Hi Charles,

How do you get your rpm to be 850 ?

The JetCat PHT3-3 is available with 3 gear ratio's giving speeds of 900, 950 & 1000

You should have your throttle set to 100% all of the time your ready to fly.

Mine gives me 904 rpm using the following pitch range..

Low = -2, Hover = +4, max = +10

Regarding the CG, as your running a multi blade head, you will want to have it even more nose heavy. When you lift the model by the blade holders, you want the rear of the skids to be higher than the front, by around 20mm

modtron
Oxford UK
11-07-2009 05:37 PM
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cossi101
New Heliman
Location: Malta

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modtron

Modtron frist of all you have a very nice aircarft .....very nice That's what is happening. tail is heavy ...when i take off the helli it is pulling back.. And it's trimed .....It's a stick flying aircarft..The trim r extacacly as you descriped.
what do you thing. modtron
11-07-2009 06:27 PM
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cossi101
New Heliman
Location: Malta

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modtron

i am flying two blades heli not four bladed... ok
11-07-2009 06:29 PM
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modtron
Veteran
Location: Oxford. UK

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With the model in the hover, because of the thrust from the exhaust, it sits very slightly tail down - not much, but it is there.

It would be very easy to still think it was tail heavy, but this is not the case. Once into forward flight, all becomes very smooth.

I do find that it helps to lean a little on the forward stick when coming into land - this helps to drive it down, rather than just slowing up to quickly and hanging with the tail down.

Ideally you want to have a good calmish day for your fine trimming.
I know that it can sometimes be a little breezy in Malta - are you flying on the old airstrip ? I've not been there since the early 80's.

modtron
Oxford UK
11-07-2009 08:30 PM
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modtron
Veteran
Location: Oxford. UK

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Forgot to mention about the exhaust.

After 2 hours of running, mine started to come apart.
I am happy to say that Vario did replace it with the revised item as shown here.

It is now braced from the bottom brace to the inlet to stop it flexing.




Keep an eye on yours - if it is starting to fail, you will notice that the vertical strut mounted inside will start to come loose first.

modtron
Oxford UK
11-07-2009 08:36 PM
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cossi101
New Heliman
Location: Malta

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Hi modtron

Yes at the old air strip in ta Qali.Modtron do you thing i phone jet cat in germany and tell them about the rpm of 850.a bit of more head speed it cames more stable i thing.my turbine is with two gears modifide.

11-08-2009 06:00 AM
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modtron
Veteran
Location: Oxford. UK

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Charles,

Sent you a pm.

modtron
Oxford UK
11-08-2009 10:50 AM
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cossi101
New Heliman
Location: Malta

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hi modtron

Modtron does the tail still move a bit while it's tatin.cause mine i tatin a it still be a bit lose....
.Charles
11-10-2009 03:01 PM
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modtron
Veteran
Location: Oxford. UK

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Hi Charles,

I find the tail very solid and powerfull when needed.

What are you using for tail servo, & gyro ?

How much gain are you using on your gyro - HH mode or rate mode ?

modtron
Oxford UK
11-10-2009 09:43 PM
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cossi101
New Heliman
Location: Malta

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Hi Modtron

No not the tail flying i mean. That's good i am useing the 401 gyro futabia s 9415 digital servo 9.5 kilos very fast.Modtron i am telling you When you tie the tail with the fuselage.My tail keeps a bit slug.Does your heli tail keeps a bit sluge ...?? The turbine i had to send it back to germany.Max told me to send it back to change the plastic gears to incease the rpm to 960 and sevice the turbine for puffing on idle speed.i had to dismantel all.big job for noting.
11-11-2009 05:29 AM
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modtron
Veteran
Location: Oxford. UK

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Hi Charles,

I guess you mean the screw joint that fixes the tail boom to the main body ?

Mine is really tight, but I did skim around 3 mm off of the length of the threaded metal part, so that it would do up a lot tighter than was originally planned.

I thought you had the twin gear arrangement on your PHT3-3 already ?
So I am a little surprised that the gears need to be changed again ?

modtron
Oxford UK
11-11-2009 08:14 PM
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cossi101
New Heliman
Location: Malta

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Hi Modtron

Yes . I head to send the turbine cause they made the wrong gears,,, they made the gears for the four bladed that is 850 rpm,,, i am flying two blades.so i need more rpm. and they told me they need to sevice the turbine cause it's puffing on idle speed that's 33000rpm...
and it cost me 280 euros to send it back....So now i have to wait for my turbine .........I dont know why they dont test the turbine before the send it to the custemore........if the tested it would work poperly.
Charlie
11-12-2009 04:43 PM
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modtron
Veteran
Location: Oxford. UK

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PM sent.

modtron
Oxford UK
11-12-2009 08:16 PM
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Ron’s HeliProz South . MTA Hobbies . Model Rectifier Corp

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Scale Model RC Helicopters > vario bell 412 turbine
 
 
cossi101
New Heliman
Location: Malta

My Posts This: Topic  Forum
Hi Modtron

Tomorow 17th Nov they said that they going to ship the turbine.Max told me that now the rpm is going to be 980000 @ 962rpm.And no puffing....hope to start assemble it .....Looking foward to fly...
Charlie
11-16-2009 02:24 PM
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CarbonXtreme . Midland Helicopters . HeliProz

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Scale Model RC Helicopters > vario bell 412 turbine
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