I am a beginner R/C heli pilot, still flying with my training gear but the number of hard landings has decreased drastically! My heli (a Hawk III with MDS .38 motor) seems well set up, blade balancing and tracking done, no funny quirks, and she hovers well in still air/slight breeze.

My question: I was flying in some breezy/gusty conditions - wind varying from nothing to about 10mph - maybe even bursts of 15mph. When there was no wind, the heli practically hovers hands off for 4-5 seconds. As soon as the gust of wind comes, she will climb rapidly from 1 metre above the ground to about 5 metres within 5 seconds (with no change in controls from me!!) - also she starts pitching forwards into the wind. This is a storm in a teacup for a beginner.

Is this normal due to some helicopter aerodynamics I do not understand, or is there some adjustment to be made?

Any advice on sorting out similar experiences would be appreciated ......

I don't know the technical answer, but when the wind blows it lifts the heli up in a matter of seconds. One thing to be carefull of is not to re-adjust your throtlle once this happens because as soon as it stops blowing it will come back down to its original position without you having to pull down the throttle. Natural instinct tells you to get it down quick, and a lot of people just slam their stick down, the wind stops blowing and the thing falls like a brick.

After you get more competent at hovering then you will soon feel these changes faster and compensate for them before it even lifts up. You can decrease throttle/pitch to get it down, but take it steady at first and be ready for it to come down a bit faster if the wind stops.

How's your MDS going? I used one in my plane, but could never get the thing tuned up properly.

James

PS: Once you've learned to hover in normal conditions, it will be good for practice to hover in a slight wind, you'll have to fight harder to keep it in a steady hover and you're responses will quicken.

when flying in winds that fluctuate either side of 15mph you are experiencing translational lift...

Effectively you are in forward flight so heli is tipped forward and has to power into the wind to stay still...

A big gust gives more translation lift and you have to back off on the collective...

This is much harder if you arent flying in idle up as the heli tries to auto down into the wind when you drop the colective and you can find yourself with a lack of headspped if the wind drops....

You will soon learn it tho...

welcome to helicopter aerodynamics 101. this will be the first of many of your questions regarding these great machines. here is a link for more info on translational lift............

RCUniverse - The Ultimate RC Forum! > RC Helicopters > Helicopter General Discussions > Helicopter Aerodynamics

Flying in idle up is a good point. I've been hovering ok and doing basic forward flight for the last few flying sessions, but it wasn't until i programmed idle up that i began to feel in control. Everything seems easier in this mode.

Thanks for all the advice guys, makes a big difference.

James, to answer you question about my MDS motor: mine is fine. My buddies' MDS motor seems to be erratic. I got a model about 2 years later than his though, so I think they have improved a lot. I have heard some horror stories about MDS, but I can tell you that mine starts fine, idles nicely and performs well.

Its probably not quite an O/S, but at the price it does the job!!

i have a question about going in idle up. i saw a video of a guy you flew his heli, then landed it, but kept it spooled up and then put it in idle up. you could hear it speed up alot more but it stayed sitting on the ground. i think it was a trex. is that how your suppose to do it, or when your in the air? also when you fly in idle up is that when you really need to worry about the pitch of roto blades?

Idle up pretty much sets a constant throttle and you are only varying pitch with the left stick. It depends on your programmed throttle curves but I pretty much so run 100 percent throttle in idle up.

You can pretty much switch in and out of idle up whenever you want, on the ground or in the air. As long as your curves are matched up between the modes, your heli shouldn't try and go climbing or descending crazily when you switch. I generally tend to bring the heli into a hover and then flip the switch, I prefer at least a little distance between the ground and heli when I switch.

how do you program throttle curves? can this be done with stock belt esky tx?

no, unfortunately the throttle curves on the stock tx is are set. 0 - 50 - 100 in normal mode and 100 - 50 - 100 in idle up (bottom - mid- top stick positions). The pitch can be changed though.

Read through my [link=http://www.rcuniverse.com/forum/m_6957235/tm.htm]post[/link] on the transmitter.

rdevtr1000,
I don't run 100% throttle all the time in idle up but I do run a much higher throttle than I do in Normal mode.
How do you match the hover point?
I suspect you run less pitch, right? If so do you find this throws the head speed up to a crazy RPM?
What values are you runing for your throttle and pitch curves?
I only got my Trex 450 before Christmas as due to the weather I have only flown it out door twice and not had a chance to play with the values properly. Nice little heli though.

Cheers,

so basically, with the motor unplugged, i take it to half throttle and i flick the idle up switch, my main blades don't seem to move any and i see the servos move just a tad. does that mean when i spool up to 50 percent throttle that my heli shouldn't go shooting up in the sky when i flick the idle up switch?

Correct. The rpm of the motor will increase and the heli might move up or down a bit during that idle up transition, but if you are prepared for it you will be ok.

i got my nerve up and tried it, i did it with it spooled up sitting on the ground, i saw the heli boucne a little but that was it, pretty cool seem to run my battery down a little bit faster though

Cool! Just remember to always have the TX in normal mode and throttle sitck all the way down before you plug in the battery. But yup, the battery will run down faster because the motor will be running at a higher rpm in idle up.

Be careful though.. if you make the transition from idle up back to normal mode with the stock tx while the heli is on the ground the heli "could" jump up in the air a bit during the transition back to normal mode because of the stored energy in the blades/head.

Another weird thing you will experience is how the heli reacts laterally to gusts of wind. I've experienced that the attitude of the rotor disk relative to the wind will cause some unexpected actions. I have felt a gust of wind on my back that will cause the heli to suddenly come towards me. Nothing gets your attention like a head-high flying lawn mower coming your way. Hover at a safe distance out.

My 2 cents.