How Long Is To Long?

[Dilbeck]

What would be the longest main blades to use on a Hawk Pro 30? It came stock with 550mm blades. I put some 600mm carbon fiber blades on due to a crash because thats all the hobby shop had. Man what a differance that made in stable hover the os37 didnt even seem to mind the extra load at all. The only draw back seemed to be the tail seemed to drift a little with the gy401 and could not get it to stop all the way no matter how much adjusting i did. Does anyone think maybe the down wash from the 600s overlapping the tail blades keep the tail from being able to work properly?

[hawkman]

No...but the extra torque might have something to do with it.

I would take the linkage for the tail rotor control...and adjust this...try one turn. You are aiming to put a little extra pitch on the tail rotor...this will counter the torque better...the Gyro is working ok I suspect...but it can only do so much.

As long as the blades cant touch the tail rotor then by all means use 600 mm blades.

I used to fly a Hawk Sport, good heli it was. Nitro is expensive to get where I live so I switched to petrol...got myself a Predator with the 231 engine. I like Centurys stuff...not sure about the manuals though...and the customer service over the phone is rubbish...from an overseas perspective anyhow.

Rob

[Dilbeck]

Hey hawkman ive spoken with you many times and always got good advice, Love the 600mm blades but i wondered why a lot of manufactures go to an extended boom when going up in rotor blade size/length. It would seem that the air blowing down from the main blades would wash out (somewhat) the tail some. What if i had the enough engine to run 800mm blades and the blades reached all the way to where the tail rotor was under the main blades? Thats a lot of air pushing down and counteracting the tail pushing to counter the torque of the heli. When you said (extra torque) by that did you mean the extra torque required to turn the larger 600mms? And yes the 401 was working great with the 550s but no matter what little or large adjustments i make with the linkage it seems to drift a little less or more based on head speed. It acts like i can get it perfect at hover but add some speed and the tail gets overcome with downwash. Im putting the 550s back on to do some test. Thanks for all your help...

[hawkman]

I guess a longer boom would help, not sure about the 50 sized helis of centurys...maybe you could upgrade slightly? I havent tried this so cant comment.

I tried flying with 500mm blades once...what a difference, the heli would hardly lift off...and was unstable too..then again the engine was an MDS...the Hawk did not like that engine at all..had to get an OS32.

I am not sure about the downwash, it could affect performance of the rotor.

I think that regardless of headspeed you might not get over this problem..if you can live with it for now I wouldnt worry...might be worth getting a longer boom and tail drive. If you like the 600mm blades why change?

Its amazing how much difference those extra mm's make. I have heard it said that the last third of a blade makes a big difference to performance. I would agree with that. There is no 'washout' on a standard RC heli blade...by this I mean the twist that yuo would see on a real helicopter...washout means the blade tapers in pitch...so the closer to the hub you go...the greater the pitch...or twist in the blade...this is because the blade naturally is travelling slower as you go along to the hub...therefor the pitch needs to be that bit greater to equalise lift.

I dont know why RC helis dont have this...the fixed pitch models do...take a good look at the CX 2...Its not washout in the strict sense...more a taper of the tip.

Rob

[Dilbeck]

Well noted, just took a look at my cx2 and the blade at the hub is 2 times the width as the tip. Also ive been told by many that the last third is where all the lift is and is why you should track the blades with a guage on the last third of the blades. Ive tried this and have never had a blade tracking problem. One other thing ive learned is take off the main blades and just leave the head and flybar, Spool it up and watch the wobble, move one of the flybar weights in a little, check again if worse check the other side. I have found its the easy way to ballance the flybar and really makes a lot of diff not only at hover but in ff flight!! You may already know this for its not easy to ballance the fly bar once installed. Sorry to get off track, I think i will stay with the 600mm blades from rotor tech it just flys so much better no mater what little drift i get. Will also look into an extended boom. The bergen gasser comes with a standard version and a EB (extended boom) The extended boom version is set up for longer blades. That is the only diff between the 2 and at the same price $1500 Thats $500.00 less than the century condor except it comes with no blades. Will be talking soon i hope! Good day to you, Its 50 deg in arkansas today but 55 tomorrow with little wind. Flew 2 tanks today tweeking the rebuilt hawk after a major crash and its soooo smooooth now.

[hawkman]

Good point about the flybar and paddles/weights...I never thought about that makes a lot of sense though.

I will try this out sometime with the Predator, be a good thing to do with the Trex too...thats one difficult critter to get right if it is out of balance...least I can hold it with one hand while checking how it runs...wouldnt dare try this with the gasser!

You thinking about going for a Gasser? The Condor looks like an amazing buy...the servos and other bits and pieces are pricey. I paid about £1500:00 sterling for my Predator...the only item I had was the radio...everything else had to be included with the heli kit.

Been flying a lot this last few days...got an hour in total yesterday. Just got back from flying around the local Airfield...that was fun...got a couple of photos taken of me which I will post up soon.

Rob

[zakeytech]

it’s just my cup of tea