Chinook Chat!

[Kathi]

Let us discuss the many complexities associated with the Chinook design bonus
Some ideas...
Should either rotor be left handed, right handed, or both?

Should the middle of the design have an Ultrafilm covering, and why is this helpful (esp. given if the 2 rotors go in opposite directions)?

Are most teams doing this? Are YOU doing this?

What are the flight times with the Chinook?(Apparently a Nats heli. winner got above 3 minutes with his/hers)

Additionally, if you have tried making a Chinook design, please describe your experience so we all can benefit from it

Thanks!

[Unome]

Should the middle of the design have an Ultrafilm covering, and why is this helpful (esp. given if the 2 rotors go in opposite directions)?

I'd anticipate that this is a good idea, based solely on the fact that this is how the FFM kit is.

What are the flight times with the Chinook? (Apparently a Nats heli. winner got above 3 minutes with his/hers)

This was 2012 - I don't think the dimensions were much different, but I'm not certain.

[glouthan]

First post here and long time reader of these forums so I finally decided to get an account!

Anyways, I just finished building and testing my first Chinook and although it was not as successful as I would have hoped, it is definitely a solid time so i'm looking forward to hopefully improving this.

One of the things I've realized is that it is very important to incorporate stability vanes in both directions (left/right and backwards/forwards), but does anyone have any other ideas on how to keep the lift from the two rotors equal so the helicopter doesn't sway sideways? Im using 2 rotors each with their own separate motor stick but I'm realizing that as soon as one motor begins to loose its elastic energy the entire device comes down because of the uneven lift... We will dig out the torque meter from the storage closet next but just thought I'd post here to see if anyone had any other ideas.

[andrew lorino]

First post here and long time reader of these forums so I finally decided to get an account!

Anyways, I just finished building and testing my first Chinook and although it was not as successful as I would have hoped, it is definitely a solid time so i'm looking forward to hopefully improving this.

One of the things I've realized is that it is very important to incorporate stability vanes in both directions (left/right and backwards/forwards), but does anyone have any other ideas on how to keep the lift from the two rotors equal so the helicopter doesn't sway sideways? Im using 2 rotors each with their own separate motor stick but I'm realizing that as soon as one motor begins to loose its elastic energy the entire device comes down because of the uneven lift... We will dig out the torque meter from the storage closet next but just thought I'd post here to see if anyone had any other ideas.

Maybe allow the body to spin a bit to balance out any imbalances?

[daydreamer0023]

First post here and long time reader of these forums so I finally decided to get an account!

Anyways, I just finished building and testing my first Chinook and although it was not as successful as I would have hoped, it is definitely a solid time so i'm looking forward to hopefully improving this.

One of the things I've realized is that it is very important to incorporate stability vanes in both directions (left/right and backwards/forwards), but does anyone have any other ideas on how to keep the lift from the two rotors equal so the helicopter doesn't sway sideways? Im using 2 rotors each with their own separate motor stick but I'm realizing that as soon as one motor begins to loose its elastic energy the entire device comes down because of the uneven lift... We will dig out the torque meter from the storage closet next but just thought I'd post here to see if anyone had any other ideas.

Maybe allow the body to spin a bit to balance out any imbalances?

I guess, as long as it doesn't provide lift, it wouldn't count as a rotor?

[wx4caster]

We have built the FF chinook copters but as others have stated, they are very fragile. So we decided to build a holding rig to make loading the motors easier. We used pictures from Dave's instructions to build a rig similar to his. (He didn't provide any dimensions for a rig, which is understandable considering how busy he is) I have put together a two page powerpoint showing all the dimensions we have used, in case anyone is interested. It turned out really nice, and hopefully testing later today will go more smoothly.

So far our times are not very impressive. (thank god for the bonus). Our copters are very heavy compared to the minimum allowed. So fighting gravity.

[coachchuckaahs]

wx:

Like you, we have found that weight is critical, every tenth of a gram is worth maybe 5-15 seconds, depending how well you re-optimize the rubber after weight changes.

In addition, balance of torque and pitch on the two rotors is absolutely critical.

With bottom rotors, some robustness is needed as well, as damage near tips of the rotors will substantially impact the next flight. Even if repaired, a slight change in tip pitch will dramatically impact. We are using an old Prather pitch gage to verify tip pitch. You could make something like Dave's prop pitch gauge, adjusted to measure at tip of 30cm rotor. To address this, we just rebuilt our rotors with two wraps of thread and a small dot of CA where the tip ribs join the spars. Hoping that makes flights more repeatable. May consider increasing durability by catching the heli in practice rather than hitting the floor, especially if the floor is carpeted. Of course, catching is fraught with risk as well!

Like Wright Stuff, those who practice more will do better in contest. So many things that can go wrong, the basics must be ingrained and rote. More data = better flights!

Chuck

[wx4caster]

Okay everyone,

Some have requested a copy of the plans I used to build a Chinook copter holding rig. I used Dave's original design and made up plans for it. I sent a copy of my design to him and he loved it. So it has his blessing.

https://www.dropbox.com/s/f6ceox9swjhmd ... 2.pdf?dl=0

Hopefully this will make loading the motors on the Chinook less stressful.

[Nano1llus10n]

Just wondering, but is there a possible way to reinforce the perpendicular fins without adding too much weight? The fins are way too fragile and it's frustrating to keep fixing them.

[Unome]

Just wondering, but is there a possible way to reinforce the perpendicular fins without adding too much weight? The fins are way too fragile and it's frustrating to keep fixing them.

1/16 x 1/16 hypotenuse pieces? If you only reinforced the joint between the fins and the axial connector (e.g. 8 1-inch pieces), that would add less than 0.1 grams for sure (no idea whether that's too much though)

Like so (dots are blanks):
..............|
............/.|.\
.........../..|..\
........../...|...\
.____/__|__\____
(and mirrored on this side)