Ray's Blazing Star Mods

[Raygun]

Yes it has and it wont be long and there wont be any stock parts it flys better than I can control it that is just right. The BS has a center shaft of 2.5mm the Big Lama has a 3mm center shaft I got all the bearings I need I just have to bore the gear or turn the shaft down on the gear end I think I will bore the gear I can bore it straighter than it came from the factory anyway. Then comes the gyro and maybe duel swashplates. Ray

[19000rpm]

Ray did an amazing job on my wifes Blazing Star upgrade and brushless conversion. I'll post a photo when I get my daughters camera. The paint job, candy apple red, and custom decals "Lady in Red" were the crowning touches. It will hover hands off an flies like a dream. Such a far cry from the stock bird.

Happy landings

[Raygun]

Thanks 19000 that was a tight conversion with the 53#1 canopy I think the wiring turned out nicer than mine practice makes perfect I guess. I am installing the big lama metal conversion on mine I tried using a CF outer shaft but the big lama uses a 3mm inside shaft instead of a 2.5 like the BS so there was a little friction so I went back to a metal tube. I also made a upper bearing support with two bearings spaced apart rather than one this inceases the stability of the upper set of blades. I also installed a pair of venom gears the face of the gear is as wide as the motor gear and the gears webing is much heavier..I should just make a Big Lama but as I understand xtreme is coming out with all kinds of upgrades for it Motors, shorter lighter flybars, blade grips, landing gear ect. it will be interesting to see. Ray

[cubusaddendum]

Hi All,

I've been talking to Ray for the last month or so on rcgroups about my dual-swash mod combined with his brushless mod for the Walkera 53 series. He recommended that I start coming here.

Dual swash-plate progress
www.youtube.com/watch?v=JKcxbFGm5gY
www.youtube.com/watch?v=pcPVTqu63xU

Since this footage was taken I've fitted Ray's brushless mod (Alpha250 motors, HobbyWing Pentium 10A ESCs and the 2BLC converter), along with head-lock gyros on all 3-axis (1x EFLH2001, 2x ESky 0704B), and I'm looking for feedback.

1. ESC Timing mode - should I just employ trial and error until I get the most bang for my euro?
2. The 2BLC I got sent by Frank Kraehe appears to be dead (no status LED indicating initialization with a 5V BEC signal). Does anyone here think I have a dud?

Apologies to Ray whom I've PM'd about this already.

-Rob.

www.youtube.com/cubusaddendum

[Dlan]

Welcome aboard, glad to have you here. That is a very interesting
design. Have you flown it much outside yet? What's the verdict on
improved handling?

I have a Art Tech md500 that flys ok as long as I don't get to aggressive with it, then I'll get blade slap or lose the flybar. Do you think this system could correct these shortcomings?

Dlan

[cubusaddendum]

This has become a bit of a Rosetta Stone....

I have flown it outdoors, although at the time I had phasing issues that got worse with increasing cyclic pitch so I could only really hover (albeit approx 40 feet in the air).

There are two really big issues with FP coaxial helis like this (not be confused with CP coaxials - they are totally different!)

#1. Low translative flying speed.
#2. A high degree of slop in the top rotor.

Both get you in trouble when flying in windy conditions.

1. The first issue can be improved with increased throw to the swash plate and more powerful motors for higher rotational speed. If you check this video of my modded KA-50/Blade CX3 you'll see this work well in normally-prohibitive-for-CX wind conditions.

www.youtube.com/watch?v=QN77uRglaG0

2. The second issue can be improved by removing the bell bar and putting swash-plate pitch authority into the top rotor. The problem is that the neither rotorblade has been bell-hiller lag compensated. In fact, the lower rotor has a -45 degree phase shift to give an approximation to this compensation. This is why the bell bar is positioned at 45 degrees to the blades, and not 90 degrees like on a CP, and why hard cyclic control in hover is ever so slightly off centre on some CX helis).

EQMOD's classic dual swash plate approach translates the cyclic pitch to the upper rotor with a +90 degree phase shift to correct for the lower rotor offset, but I've found there is a huge potential for discrepancies in pitch to develop between the two rotors, creating axial flow interference. This is why I could only hover in tests.

Prior to EQMOD's flybarless dual swash-plate mod, he was mixing the upper rotor pitch with the bell bar. The interference got mostly drowned out so no one noticed a problem yet. As soon as he eliminated the bell bar he got into difficulties (as have I). Looking at his early videos you can see his prototype pendulum-swinging all over the place. He seems to have nearly nailed it now, although I don't understand how.

I'm not sure what the answer is yet. Stabilization with gyros on all 3 axis definitely works though, so whatever the outcome I've had that success anyway.

I'll start a thread here so you watch my progress and see if you can't do something similar with your ArtTech. I already have a phase-mixing dual swash-plate mod you might want to try:

www.rcgroups.com/forums/attachment.php?attachmentid=2477196

Jun 25, 2009 9:01:38 GMT -6 Dlan said:

Welcome aboard, glad to have you here. That is a very interesting
design. Have you flown it much outside yet? What's the verdict on
improved handling?

I have a Art Tech md500 that flys ok as long as I don't get to aggressive with it, then I'll get blade slap or lose the flybar. Do you think this system could correct these shortcomings?

Dlan

[Dlan]

That's sounds great. I hadn't been flying it much, been trying to master my Icarus FP. While waiting for parts to put it back in the air
I pulled out the Art Tech. Balanced and installed new set of blades, trimmed it out, and it seemed to fly better than I remembered until I got carried away with the controls.

I had installed links on both sides of the flybar, which is not standard on this model and I wondered if this might have contributed to the mid-air blade strikes.


Dlan

[cubusaddendum]

Jun 25, 2009 19:26:40 GMT -6 Dlan said:

I had installed links on both sides of the flybar, which is not standard on this model and I wondered if this might have contributed to the mid-air blade strikes.

Dlan

I doubt it. The high degree of pitch movement in the top rotor would be my guess as to why you were getting blade strikes.

The original Bell flybar design incorporates a dampening collar around the shaft that moves up and down with the pitch angle of the flybar. I've never seen this on an RC model, but since most modders agree that the flybar should move butter-smooth to avoid erratic behavior (that can lead to blade strikes amongst other things), I'm going to try this out at some point with my Blade CX3.

Here are some diagrams that might give you some ideas:
www.scotiabladerunners.ca/theflybar.htm

If you come up with anything, make sure you let me know!

[19000rpm]

Dual flybar control links make most coaxial helis more stable and at least a little less agile. It might help with the blade strikes too.

Happy landings

[cubusaddendum]

Jun 26, 2009 5:39:14 GMT -6 19000rpm said:

Dual flybar control links make most coaxial helis more stable and at least a little less agile.

....I would guess this is only true because you are adding slightly more friction (i.e. damping) to the system with those two extra ball linkage points. To honest though, I think there's more millage in Bell's friction collar - it's adjustable for one thing, and from what I recall it's the friction component "mu" that enables you to tune up a real simple harmonic motion system to get your desired "critically damped" behavior.

Bell seem to know what they are doing.

[Dlan]

Jun 26, 2009 2:48:45 GMT -6 cubusaddendum said:

Jun 25, 2009 19:26:40 GMT -6 Dlan said:

I had installed links on both sides of the flybar, which is not standard on this model and I wondered if this might have contributed to the mid-air blade strikes.

Dlan

I doubt it. The high degree of pitch movement in the top rotor would be my guess as to why you were getting blade strikes.

The original Bell flybar design incorporates a dampening collar around the shaft that moves up and down with the pitch angle of the flybar. I've never seen this on an RC model, but since most modders agree that the flybar should move butter-smooth to avoid erratic behavior (that can lead to blade strikes amongst other things), I'm going to try this out at some point with my Blade CX3.

Here are some diagrams that might give you some ideas:
www.scotiabladerunners.ca/theflybar.htm

If you come up with anything, make sure you let me know!

I had originally installed the extra link to help retain the flybar in my frequent crashes. I did not experience blade strikes until after I made that change so thought it might have been the cause.

After eading what you and 19k have to say I believe it is due to more aggresive flying on my part since I was going bacvk from a FP heli.

Great article you linked to. I'll have to read it a few more times to get it all to sink in ;D


Dlan

[cubusaddendum]

Yeah, aggressive cyclic input will wipe you out because the Bell flybar set-up you have is under-damped. This is related to point #2 in my post above.

When you consider the fact that both the UH-1 Huey and AH-1 Cobra use a Bell flybar system, I'm fairly sure you could mod your coaxial to get a similar level of reliability. It's just a question of damping those wild movements (especially when the flybar tilts to its mechanical limit and bounces back).

-Rob.

[Dlan]

(especially when the flybar tilts to its mechanical limit and bounces back).

Ahaa! (light goes on in head) ;D. i'm beginning to see what's going
on now. Well put sir!


Dlan