Scale Bell 47g

[fran11784]

First I want to give a big shout out to Nade on this forum for giving me tons of help with this build. Question on a violent shake when spooling down. Maiden this beast today and all went fairly well except a real bad shake when the helicopter was spooling down. This is a 800 size machine. I was wondering if tight dampening could be a cause? I'm using a Synergy E5 head on this thing and of course the dampers in the head are real tight. It also had a aileron wobble that went away at 1300 rpm. Really don't know where else to look. I do have a video I'll try to post. Thanks, T

Short maiden video:

 

[Scott Marshall]

Nice machine, and a great 1st flight. I'd go back over the balancing, check the bearings and gearing.
I once had loose setscrew on the main gear do something similar on a much smaller machine. It was chucking on the flat, but not jumping. Gear felt tight, but would slip a few degrees if you put some torque load on it. Had both the low rpm shake and wind down shudder yours does.

Classy machine!

 

[D.O.G.]

Nice going fran. That's a big sweet flying machine you have there. Good luck on future flights and keep the videos coming .

 

[Smoggie]

One thing that struck me as odd.. the tail rotor stopped well before the main rotor? Does this heli not have the tail driven off an auto gear?

Anyway, the noise seemed to correspond to the tail rotor stopping. I also noticed that the tail blades were very loose in the grips and flopping down which could explain noise on slowdown.

 

[fran11784]

Hey Smoggie, yes the tail blades were pretty loose. The tail rotor stopping, well thats a (in my opinion) a design flaw. The tail is driven off the secondary shaft so when the motor stops the tail stops. I emailed them about that and they dont have any conversion for it. Im working on a Goblin type set up but going to take some engineering to make it work

 

[Admiral]

Love the 47's, great flight for a maiden.

 

[fran11784]

Hey guys, after tryng 2 different heads I went back to Vario and decided to buy a head they recommend for this helicopter and guess what, all my shakes are gone except for the normal ground resonance. Id say this bird is complete.

 

[Tony]

Very nice fran! Glad to see that beast in the air and stable!

 

[D.O.G.]

Hey Fran. The bird looks and sounds wonderful. I love the sound @1300rpm.

 

[fran11784]

Thanks! The blades are 800mm a-symmetrical spin blades. They give a nice sound...

 

[Tony]

They give a fantastic sound, especially when slowly descending!

 

[fran11784]

Here's a throwback... 30 years separating theses two pictures....LMAO

 

[Cyclone 7]

The heli doesn't seem to have aged much

Very nice btw - fantastic sound and looks great in the air.

 

[D.O.G.]

That's too cool Fran. 30 yrs. ago, i was chasing women on the east coast of Florida and now I'm chasing helis/quads on the west coast of Florida lol. Thanks for sharing .

 

[Cyclone 7]

At least the latter still gives us a sense of 'the chase' and there is much satisfaction to be had in finally 'winning over' your heli

 

[fran11784]

I guess I should clarify, that top Bell 47 is a Hirobo gasser. I later converted it to glow. Sadly it was lost in our move to Florida in 2007. One reason I built the Vario in the videos. I think the Hirobo kit was released in 1982ish. I paid 1100 bucks for it then with the engine... Thanks