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**trillian** · 17-06-2011, 11:29 AM

I am not familiar with the Fury but have seen some posts about it from when they orignally came out some years ago. What was being
said is that the Fury is almost a .60 size airframe so it is actually a bit under powered with a 50 engine. (but this was many years ago
and possibly before the Hyper came out)

The first thing I'd look at is the blades and the gear ratio. If you have a gear ratio around 8.5 to 1, give or take
a little, you will be able to run 600mm blades comfortably with the OS50 Hyper and get around +/- 10 degrees of collective.

But if the airframe is really heavy that's something you won't be able to just adjust/tune out of.

A reasonable ready to fly weight for a .50 size heli is around 3.5 to 3.9 kg (some may be lighter than this but that's about what my
50 helis weigh and they all have OS50 Hypers that are well up to the job)

**wadders** · 17-06-2011, 11:41 AM

ah right...........thats the thing the blades are pretty big (i think) they are 640mm and weigh i think 185g............i am thinking i should go down in blade size! can you explain the gear ratio theory to me.................please....

**trillian** · 17-06-2011, 12:19 PM

Originally posted by wadders View Post

ah right...........thats the thing the blades are pretty big (i think) they are 640mm and weigh i think 185g............i am thinking i should go down in blade size! can you explain the gear ratio theory to me.................please....

Basically you need to have the engine running in it's powerband. All engines have a range where they make their peak horsepower. The OS50 Hyper developes
max power at around 17,000 rpm so, for example, at an 8.5 to one gear ratio that gives you 2000 rpm headspeed (you don't need 2000 rpm for hovering
and gentle flying but would do for aerobatics).

For longer blades you would need a steeper gear ratio because it will not be able to spin them as fast. I'm not sure what sort of speed that engine
could spin 640mm blades but it will be considerably lower than what you could get with 600mm blades which are more commonly used on
.50 helis.

Lower headspeed is going to mean more sluggish cyclic response etc.

A .60 size engine would have no trouble with 640mm blades or a bit larger.

What does the heli weigh ready to fly minus fuel? Count the teeth on the pinion and main gear to get the ratio
as a starting point to know what kind of blades you can run on there. If you can get the engine running in its
best powerband and get the headspeed up there a bit you should have fairly snappy response unless the airframe
is just really heavy.

**pgkevet** · 17-06-2011, 12:21 PM

..and your pitch range..same as large blades.. adds drag etc.
Gear ratio is like trying to go up-hill in 4th if too low.
Have you tached it?

**wadders** · 17-06-2011, 12:25 PM

ok i see what you mean. will need someone to check my head speed. the spec i think is as follows............i still think the blades are way to big for the heli..........

Length: 47.875" - 1216mm
• Height: 16.625" - 422mm
• Tail Rotor Span: 260mm - 95mm Blades
• Avg. Kit contents Weight: 5.4lbs - 2.45kg (includes painted canopy)
• Avg. Ready-to-Fly Weight: 7.3-7.5lbs - 3.31-3.4kg (less fuel)
• Main Drive Ratio: 8.538:1
• Tail Drive Ratio: 4.61:1

what you reckon????

**trillian** · 17-06-2011, 12:33 PM

You don't need to tach your headspeed, I can tell you right now that with a gear ratio of 8.538 to one you need smaller blades. 640s are going
to put too much load on the engine and it will not be able to rev into it's best powerband. Put a pair of 600mm carbons on there and
you will be running the engine where it is happiest. You should be able to run a headspeed between about 1600 to 2000 and get plenty
of pitch range. (prob around 1600/1700 in normal mode and 2000 ish in idle-up)

The weight doesn't seem excessive, maybe just a bit heavier than the lighter 50s out there but shouldn't be a problem assuming that is
accurate.

Originally posted by wadders View Post

ok i see what you mean. will need someone to check my head speed. the spec i think is as follows............i still think the blades are way to big for the heli..........

Length: 47.875" - 1216mm
• Height: 16.625" - 422mm
• Tail Rotor Span: 260mm - 95mm Blades
• Avg. Kit contents Weight: 5.4lbs - 2.45kg (includes painted canopy)
• Avg. Ready-to-Fly Weight: 7.3-7.5lbs - 3.31-3.4kg (less fuel)
• Main Drive Ratio: 8.538:1
• Tail Drive Ratio: 4.61:1

what you reckon????

**wadders** · 17-06-2011, 12:37 PM

good advice!!!
My next problem will be to get a pair of blades and hope they make a difference!!!! I hope they do otherwise i have would have bought them for nothing!
also an interesting point is my blade bolts are 5mm not 4mm so im not sure which blades to look for!

**trillian** · 17-06-2011, 12:47 PM

Originally posted by wadders View Post

good advice!!!
My next problem will be to get a pair of blades and hope they make a difference!!!! I hope they do otherwise i have would have bought them for nothing!
also an interesting point is my blade bolts are 5mm not 4mm so im not sure which blades to look for!

Where do you fly? I notice you're in woking so if you want to bring it over to BoxHill I can bring down a couple pairs of blades you can try. (I'll need
to see if they can accomodate a 5mm bolt though and I know some cannot)

----just checked and I have a pair of Mavrikks that will fit a 5mm bolt and prob a couple others but can't tell because they
are on my helis.

**wadders** · 17-06-2011, 01:10 PM

What size are the Mavikks? Do fancy selling them?

**trillian** · 17-06-2011, 01:30 PM

Originally posted by wadders View Post

What size are the Mavikks? Do fancy selling them?

These are 600mm. They are the 'patriot' stars and stripes colour scheme. I hadn't thought about selling them but
you're welcome to try them if you fancy coming over to one of the places I fly.

**wadders** · 17-06-2011, 01:42 PM

Thanks for that! only problem is i just dont get much time to get out! the next time i will prb get time to go fly will be Tuesday the 28th ;( sad isnt it!!!

**trillian** · 17-06-2011, 02:39 PM

Originally posted by wadders View Post

Thanks for that! only problem is i just dont get much time to get out! the next time i will prb get time to go fly will be Tuesday the 28th ;( sad isnt it!!!

Well that's life in the fast lane

I can often get out on Tuesdays though, prob Epsom Downs
or Kempton Park.

In any case get some pics of that bad puppy on here!

**wadders** · 17-06-2011, 02:52 PM

**wadders** · 17-06-2011, 02:53 PM

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