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helicopter doesn't climb very well

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helicopter doesn't climb very well

Old 07-08-2011, 03:12 PM
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secretspy
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Default helicopter doesn't climb very well

Hi,

I have a Century Hawk Sport, with an O.S. 32 in it, running 30% Cool Power. Also I live in Denver, (around 5,280 ft elevation).

It doesn't want to climb very well. It does so-so when going straight up from a hover, although it does sound like it bogs down a little bit. But when I'm in forward flight, (not very fast, mind you!) it doesn't want to climb at all! I can hear it bog down, the head speed drops, and it just keeps flying fairly straight and level. I've had this engine for about 11 years, and I've used it in Indiana (~600 ft elevation), California (~2800 ft elevation) and now here in Denver. I haven't used it much here yet, and I don't remember having this problem in the other locations. Could it simply be the elevation?

The needle valve likes to be at 1.5 to 1.75 turns out.

Throttle Curve:
Pt 1: 1.5%
Pt 2: 36.5%
Pt 3: 76.5%
Pt 4: 97.0%
Pt 5: 100%

Pitch Curve:
Almost linear, but more pitch kicks in when you get beyond the midpoint. It's -2 degrees at the low end, +9 degrees at the high end.

I just ordered carbon blades and a header tank, which may help some but probably not much.

Anyone else have a similar heli, with the OS32, at around this altitude? How does it fly? What's your setup? Am I just underpowered at this altitude?

I'm thinking this will be my last nitro heli, I'm switching to electric after this.

Thanks
Old 07-08-2011, 09:10 PM
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gorchew
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Default RE: helicopter doesn't climb very well

I have a Kyosho Concept 30 SRX, or at least it has some SRX parts on it. It's an old helicopter (1980's). I have had it for coming up on a year now, yet only yesterday did it make it's first flight. It had an O.S. .32 in it when I got it, I pulled the engine apart - got it running on the bench well, and yet, when it was in the helicopter it could not lift off, no matter how I set the pitch/throttle curves. The engine seemed to have good compression, anyway, I got so frustrated with it I just put it away until recently. I ended up getting a thunder tiger .39 ($130 at tower hobbies), which has more power and for the most part is universal and bolted right in - and now she flies! Perhaps your engine is too worn out for your altitude? -just a thought/suggestion, I was getting ready to convert to electric myself, but I am now happy that I didn't. I definitely need to do a little fine tuning now, staring with the pitch/throttle curves. I think I'm going to try the configuration you mentioned, sounds about right for scale flight - thanks for info - good luck
Gorchew-
Old 07-10-2011, 12:17 PM
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rotor09
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Default RE: helicopter doesn't climb very well

Yes, the higher altitude will certainly effect the performance if all else is equal. Will it effect it as much as you are reporting? I do not think so, specially on the Hawk Pro which is a very light 30 sized heli.

The higher the altitude, the leaner the mixture that is required. So if your main needle is 1.5 to 1.75 open, then it will be far too rich. Heck that is even too rich a setting at sea level for that combination.

Are you using the standard pitch curve with 0 degrees at mid stick and hover at 3/4 stick?

If so then if your needles (main needle and hover/idle screw on the other side of the carb) are set properly you should only require a throttle curve setting of about 40% to 50% at mid stick to maintain a healthy rotor speed at 1/2 stick (0 pitch), not the 76.5% you are showing. Are you sure your throttle servo arm is set properly in relation to the arm attached to the throttle barrel? E.g. when your throttle curve is set at 50%, the throttle servo arm should be 90 degrees to the servo and your throttle barrel shoyud be half opened with the arm attached to the throttle barrel also being straight vertical as the arm on your servo. Also, the throttle ATV (end point) percentages should be the same on both ends.
Old 07-10-2011, 11:07 PM
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Default RE: helicopter doesn't climb very well

ORIGINAL: rotor09

Yes, the higher altitude will certainly effect the performance if all else is equal. Will it effect it as much as you are reporting? I do not think so, specially on the Hawk Pro which is a very light 30 sized heli.

The higher the altitude, the leaner the mixture that is required. So if your main needle is 1.5 to 1.75 open, then it will be far too rich. Heck that is even too rich a setting at sea level for that combination.

Are you using the standard pitch curve with 0 degrees at mid stick and hover at 3/4 stick?

If so then if your needles (main needle and hover/idle screw on the other side of the carb) are set properly you should only require a throttle curve setting of about 40% to 50% at mid stick to maintain a healthy rotor speed at 1/2 stick (0 pitch), not the 76.5% you are showing. Are you sure your throttle servo arm is set properly in relation to the arm attached to the throttle barrel? E.g. when your throttle curve is set at 50%, the throttle servo arm should be 90 degrees to the servo and your throttle barrel shoyud be half opened with the arm attached to the throttle barrel also being straight vertical as the arm on your servo. Also, the throttle ATV (end point) percentages should be the same on both ends.
All very good advice and well explained. That should help a lot, if his problem is engine related.

But another item to consider, if he has recently replaced the feathering spindle after a crash, is the location of the two washer/spacers that go between the nut at the end of the feathering shaft and the outer bearing in the blade grips. One is smaller then the other and the smaller one should be located between the larger one and the outer radial bearing. If it is reversed, with the large washer located against the bearing, it will bind against the bearing and restrict the collective pitch when the rotor comes up to speed. It will feel fine on the bench, but bind when the centrifigal forces of the rotating rotor pull the blade grips outward.
Old 07-11-2011, 07:52 AM
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secretspy
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Default RE: helicopter doesn't climb very well

rotor09, It's a Hawk Sport, not a Hawk Pro... not sure how much weight difference there is between them. Anything leaner than about 1.5 and it starts to lose power. (The engine manual says to use 1.5 as a starting point).

I've messed with the curves and things since my original post, both are now more linear than before. I did notice that I was missing a screw on the muffler, and the gasket was non-existent, so I fixed that problem. Performance is slightly better than it used to be, but still not where I'd like it to be, though. It does seem to be making more spots on the pavement than my friend's Raptor, and it does seem particularly messy when I'm done flying, so now I'm thinking the crankcase or head gaskets may be going bad... (a ha!)

What is the "standard" pitch curve? I just started with what it said in [link=http://www.centuryheli.com/support/manuals/1000bsportfull_pdf/2nd_pdf/35.pdf]the Hawk manual[/link]. It's not zero at mid-stick, that would be more of an Idle Up 1 or 2 setting, wouldn't it? I'm running it in "Normal/Hover" mode for now. It goes from -2 at the low end to +9 at the high end, so at mid stick its about +3.5. Manual says mid-stick should be around 5, although it really can't be "linear" then. I'm unable to check it at the moment, but I'll play around with it some more.

rotordoc1, this heli has never been in a crash. Interesting point though, but not having it in front of me at the moment, I'm not quite sure which parts you are referring to. Do you have a picture?
Old 07-11-2011, 08:29 AM
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rotor09
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Default RE: helicopter doesn't climb very well

oops, sorry about the duplication.
Old 07-11-2011, 08:31 AM
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rotor09
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Default RE: helicopter doesn't climb very well

Ah, the Hawk Sport! The weight is about the same as the Pro, but it as an older version (from about 8 to10 years ago) that does not have a lot of the refinements found on the current Pro version.

At that time, it was rather common in sport flying, to hover at half stick. Consequently back then, it was also rather common for many manufacturers to have set-up instructions that gave a set-up for hovering at half stick. I flew with that type of set-up on all my helis for over 15 years before getting into 3D flying.

Obviously, this would lead to a different pitch and throttle curve from a linear set-up. If you are just sport flying and are comfortable hovering at half stick then doing a set-up that is conducive to it is fine.

As I now have a 3D set-up in idle 1 & 2 this means any hovering in those mods will mean I will be hovering right side up above half stick (closer to 3/4 stick). As I find it mentally more comfortable setting my helis so that they hover in ALL mods at the same stick position, I also set my normal for a hover at the near 3/4 position.

In the type of set-up you are proposing, with a hover a 1/2 stick, having a linear collective is not really that proper, specially with the mid at 3.5. So in order to get a hover at 1/2 stick you would have to adjust your mid stick point to give you 4.5 to 5 degrees of pitch (this depends on the rotor speed you are setting up to fly at).
Old 07-18-2011, 10:16 PM
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Default RE: helicopter doesn't climb very well

The 30 powered helis are weak at sea level, you really should try carbon main blades first the stock woodies are not worth much and they can twist losing power. You should be hovering at 5 to 6 on the pitch guage about half stick and have up to 12 degrees at full up. If that doesn't help then consider selling it and getting into a 50 to 90 sized bird at your altitude to get any decent performance out of it with bigger blades and more HP. My Raptor 30 has the pro39 engine and rototech 550mm carbon blades shown below they really helped its performance out but it's a 6 pound weakling next to my 50 heli with 600mm blades about half the vertical climb speed and punch.
Old 07-19-2011, 08:13 AM
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rotor09
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Default RE: helicopter doesn't climb very well

The old OS 32 does not give a 30 heli the power it deserves, but a Hawk PRO with a good set of blades and with a good engine like the OS37 or Toki 40 is surprisingly capable as it will then have as good or better a power to weight ratio as any of the older and heavier 50 sized helis (e.g. my Hiroo Sceado/Evo).

This video is an example of what I mean:

http://www.youtube.com/watch?v=tlxS4...layer_embedded

That video is what prompted me to put the OS37 in mine a few years ago and it really came to life. It now has over 400 flights and I now fly regularly it as often as my 50's.

As yours is the old Hawk SPORT, I am assuming the engine is also an old 32 and may have seen its better days, so it may well be ready to be retired for a newer one.
Old 07-19-2011, 04:25 PM
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secretspy
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Default RE: helicopter doesn't climb very well

Thanks everyone. I put new gaskets in it and got a little more power but still lacking. I can comfortably fly it "like a plane" and maybe do some loops and inverted hover, but nothing harder than that. I'm thinking the altitude, age of the engine/helicopter, the fact that I never used after run oil, its only a 32, etc, it may be just too frail. This is partly why this will be my 2nd and last nitro helicopter. I'm going all electric after this one, especially with the price of lipos at HK. Working on an FPV tricopter now too ...no pitch curves or needle valves to worry about...
Old 07-19-2011, 08:42 PM
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jamesc43
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Default RE: helicopter doesn't climb very well

secretspy,

You should be hovering at around the 4.5 deg point and around 60 to 65 power. Maximum pitch is around 9 to 9.5 degrees. The air here is just
to thin to get the power of OS 32. It is the same issues across the board on the 32 class engines. Even the TT 39 engines don't add a significant
amount of power to overall power loss from our altitude.

The other issue is heat (air temperature). The fact is that cooler air is more dense and produces more power. This isn't issue if you have a 32 size
heli powered by a 50 but it does matter is it is a 30 class heli powered by a 32 engine.

Carbon blades will make the rotor system cleaner and consume less power overall. It is a performance enhancement but only if you feel confortable
enough to be able to replace them when and if you crash.
Old 07-19-2011, 09:46 PM
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Default RE: helicopter doesn't climb very well

There is a simple yet significant design difference in the rotor head of the current Hawk Pro, that is not part of the old Hawk Sport. It is the sleeve that fits inside the damper & the spacer that fits between that sleeve and the inner race of the bearing blade grip. The collective response when going positive to negative or vicea versa s much improved with this assition as is the cyclic response and precision.
Old 07-20-2011, 07:36 AM
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Default RE: helicopter doesn't climb very well

Under powered heli
High density altitude
Bad Performance

Its true of full scale as well.
Old 07-20-2011, 07:00 PM
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Default RE: helicopter doesn't climb very well

I replaced my wood blades on another heli after it was doing the chicken dance just getting up to lift off speed. I noticed they could be twisted by hand where the FG and carbon blades not a bit of twist. I would recommend a 500 or bigger electric after flying the 30 nitro bird the smaller ones get small fast are really hard to handle in the slightest breeze and are actually harder to fly.
Old 01-10-2012, 12:08 AM
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Default RE: helicopter doesn't climb very well

serve a lot,good

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