Hughes 500E fuselage

[crsorrell0653]

Hi

Finally got my 500E off the ground yesterday (T Rex 600 flybar). Slightly tail heavy but trimmed up ok. Running 1800 and 2050 head speeds.

Not used to landing these scale canopies, obviously I put it down slightly harder than I should have (very average landing for a normal 600), and the skid assembly goes straight up through the plywood floor base. On closer looking at the engineering, this was inevitable.

Have now put a 3mm aluminium base plate to connect the skids to the helicopter frame itself, so the landing load is taken by the mechanical frame, rather than the canopy.

Any body else found this to be the case?

[cobieg]

who makes the fuse?

[crsorrell0653]

Originally Posted by cobieg

who makes the fuse?

Might be the Align version of the Police Heli in Blue, Green and white, not sure.

[Andy01]

Could I suggest slowing it down a bit. IMO 2050rpm is MUCH too fast for a scale 600 unless you plan to do aerobatics with it. I would think that around 1500-1600rpm is a better headspeed that will provide you with a much less "jumpy" heli and longer flights.

Colin

[cobieg]

Any pictures of damage and repair?

[crsorrell0653]

Originally Posted by Andy01

Could I suggest slowing it down a bit. IMO 2050rpm is MUCH too fast for a scale 600 unless you plan to do aerobatics with it. I would think that around 1500-1600rpm is a better headspeed that will provide you with a much less "jumpy" heli and longer flights.

Colin

Flies like a lame dog at 1600 (too much weight with the canopy), and in risk of not recovering from a close call, I find it very smooth at 1800 with good response, and quite a bad vibration at 2050. Any suggestions on blade types, it has some cheap 3D blades on it at the moment, but do have a set of Align blades I could put on it.

It seems to hover well, but there is a tendency for the nose to rise in forward flight, so have to keep pressure on the stick to keep the nose down, is this fairly normal for flying a large scale canopy (thinking wind / airspeed providing lift to the body).

The repairs looks good and will get some pictures when it is daylight again. Needless to say, am now very conscious of putting it down very gently now I have it back in the air.

[Andy01]

Is your CoG slightly nose heavy - it needs to be ? It shouldn't tend to rise during FF. I did have a set of cheap plastic/CF scale blades that flew very badly in FF and tended to balloon/porpoise a lot, so blades can account for it.

I prefer wide chord blades - Spin Asymmetrical are what I have on my little UH-1N, and HeliTec 820mm x 64mm (4 of) on my EC-145. Depends if you plan to keep it as 2 blade FB or get a 4 or 5 blade head. With 4 or 5 blades you could use narrower chord blades. The most important thing is to use decent quality and well balanced blades.

I fly my 500 sized UH-1N at 1700rpm, and it flies well (2x 465mm Spin blades) - nice slow response. I have 4x 600mm fairly cheap (but perfectly balanced) GF blades on my Seahawk which weighs 19lbs, and it flies well with good responsiveness at 1350rpm. I am inclined to think that if it is flying badly at 1600rpm, it is either something wrong with the setup, or your flying style is fairly aggressive (more so than typical smooth gentle full scale-like flying).

As with most scale you need to get used to anticipating and managing collective, and avoid descending into your own rotor wash - that often ends badly.

Colin

[crsorrell0653]

Thanks for the tips Colin. I'm trying to come down to earth a bit in my flying style, as I use a Blade 360 Trio as my Crash and Learn machine. So collective management will need to be tamed down a bit.

This heli is very slightly tail heavy by about 10mm, but sits well in the hover and slow forward flight. I was reading about he Transitional Lift effect in forward flight that causes a real heli to do the same thing, it will also cause the heli to pitch as the dissymmetry of lift kicks in.

Would a simple forward trimming of the elevator be easier than trying to rebalance this heli (ie put some forward bias in the sub-trim menu)? I was forced to put the 600 unit slightly forward in the canopy as the servos wouldn't clear the canopy, so this had the effect of putting the canopy weight slightly aft of the cog.

How have you set up your pitch curve for scale flying, given a flat throttle curve. Should I use some expo to soften it up a bit?

[Andy01]

It is quite important to get the CoG a bit nose heavy - when you slowly lift the heli with the blade grips at 90° to the tail boom the rear of the skids should probably lift off the floor about 1/2" or so before the the front of the skids lose contact with the floor. It is worth looking at weight redistribution (eg. move lipo forward) or ballast weight in the nose to get this right.

I use the Set RPM governor mode in my Castle ESCs to get a nice constant rpm - better than a flat TC which varies as the voltage drops.

As for pitch curve, I tend to keep it simple. A basic linear 2 point curve with the bottom point at about -ve 3 to 4° and the top point at about +ve 10-12°. This will give you a midpoint around 4-5°, which is where it will lift off. I do try to set it up mechanically and in the FBL unit (I use Skookum SK720) to achieve around 16-18° of total pitch movement (both positive and negative), and then fine tune with the PC. I do not set up like a 3D heli with -12° to +12°, with midstick at 0°.

I do use expo - usually around 25-30%.

All of this combined with a well set up (mechanically) heli with a nice low headspeed usually makes for a nice docile scale heli that can fly in a similar fashion to the full size.

Colin

[crsorrell0653]

Colin, thanks for all that great advice. From the Pitch curve it sounds like at mid stick this thing is starting to fly, and using expo will soften that curve even more, good stuff.

I had a friend video my flight yesterday, and on lift off the tail comes up first and it takes off perfectly level and stays there. If the cog was any further forward it would walk. The set up in this canopy means the mast is sloping forward a few degrees which explains why it sits level in the hover. I can try to add weight to the front so the static cog is forward, but I am suspecting it will walk on take off. ( The fellow doing the filming was a helicopter mechanic for many years and was blown away with how stable this was). The biggest issue for me is trying to put it down like a feather, and it seems you need to land it about 300mm above the touch down spot and then let it slowly come down by itself. No cowboy stuff

[crsorrell0653]

Had an interesting event today. Decided to try and fly at the lower head speed of 1600rpm. It wouldn't lift off the ground cleanly and once airborne developed an almighty vibration, that was just on the point of destroying the canopy when I flicked it up to 1800rpm and in a second it had all gone, and flew perfectly. On landing I noticed the head gear beneath the rotors had chewed away at the canopy which meant there must have been sideways movement of up to 12mm each side. I tried to do this myself and could only get half that amount of movement, so the forces must have been huge.

I ran this past my helicopter mechanic friend, and all we can put it down to is possibly the retreating blade stall that was causing a terrible resonance. Any one else had this at slow head speeds. I had the same set up as a standard 600 and it flew fine, but thinking the extra weight of the canopy, and possibly the blades I'm using are just too much for that headspeed.

Also noticing on this model that I need very little left aileron in a turn, almost fighting to keep it in balance.

[Andy01]

Check that your mechanics are braced to the fuselage at the top as well as the mounting bolts at the bottom. Resonance can be very destructive - there was a video a few years ago of a Blackhawk exploding while hovering in ground effect - it literally blew the entire mechanics out of the fuselage.

Colin

[crsorrell0653]

Originally Posted by Andy01

Check that your mechanics are braced to the fuselage at the top as well as the mounting bolts at the bottom. Resonance can be very destructive - there was a video a few years ago of a Blackhawk exploding while hovering in ground effect - it literally blew the entire mechanics out of the fuselage.

Colin

Hi Colin, I hadn't thought of that and was trying to keep the fuselage free from contact at the top. But I can see the logic now. I will have to do some modifications to achieve some sort of passive connection between the helicopter frame and the fuselage. Thinking a soft rubber buffer to connect the two. Thanks for your interest.

PS, do you have a link to that video of the Black Hawk, can't seem to find it on Uncle Google

[Andy01]

Here you go.

http://rc.runryder.com/helicopter/t578789p1/

I have used rigid braces on my Seahawk - just light strips of aluminium from top of mechanics to top of fuselage (just under removable doghouse cover.

Colin