Tapered Aluminum Tube

[Sceadwian]

DK, when are we gonna get some photos of your ongoing build anyways?

 

[Rolf]

Sounds good to me. How much time is it going to take for a mould?

Probably use the hard paper core of a toilet paper roll.

No mold is needed! Just make a inside form out of a dowel. Proper construction must be followed so it can be extracted after the fiberglass cures.

 

[dknguyen]

DK, when are we gonna get some photos of your ongoing build anyways?

Perhaps when I actually have it in front of me and start building it. In the past, I have dedicated to projects too quickly (too quickly as in months of planning, but some realizations came after receiving the parts that have resulted in the accumulated waste of a few thousand to date). So I'm being real careful now.

Still got those parts too. Anyone interested in the wheels, suspension, drive, and chassis for a Jeep Hurricane-style steering robot? Or a 1lbs payload ripstop-carbon slowflyer with drive systems and servos? Or a quadcopter airframe + motors? (actually I'm probably going to do something with the quadcopter in the future).

 

[Sceadwian]

Damn, and I was going to say I was interested in that part =)

 

[dknguyen]

I actually have two of them. Probably only need one.

 

[Boncuk]

Still got those parts too. Anyone interested in the wheels, suspension, drive, and chassis for a Jeep Hurricane-style steering robot? Or a 1lbs payload ripstop-carbon slowflyer with drive systems and servos? Or a quadcopter airframe + motors? (actually I'm probably going to do something with the quadcopter in the future).

I'd be interested in the quadcopter airframe to be used as crop duster. What is the payload it can carry using electric motors? I'll replace them with reciprocal engines of 10ccm each. Endurance is no problem since it can be refuelled quickly.

I could use it for a present for my brother in law who dusts the rice fields manually and after the work is full of mosquito bites.

Boncuk

 

[dknguyen]

It's a tiny electric one. THere's no point to using an engine-quadcopter. The only real advantage quadrotors have is mechanical simplicity. The only other advantage is that rotors are smaller and safer, but this sacrifices efficiency. Replacing them with 4 engines, or 1 engine with all the associated variable pitch propellers and control rods completely negates that. You might as well using the traditional single rotor helicopter. It's only really useful for experimental use (like if you are interested in the control systems but cannot be bothered to work on the mechanical aspects of a helicopter).

Electronic stabilization is a must for quadrotors (no mechanical workarounds like in traditional helicopters). THe RPM of the engines relative to each other is also critical (and they need fast response time or the machine will be unstable)...and let's be honest...engines suck at those two things, so you pretty much can't use 4 engines. It's either 4 electric motors, or one engine with all associated variable pitch controls which defeats the advantage of mechanical simplicity (it becomes the same, or a bit higher than a single rotor helicopter). Even if you could use 4 engines, that means the failure rate is x4 and the engine weight is x4 (the quadcopter cannot lose an engine and still fly so it's not redundant, so if you lose one engine you are going down).

A plane would be better suited for your purposes anyways (lighter, higher payload, more efficient, easier to maintain, and easier to fly)

 

[Boncuk]

Thanks for your reply dk,

Helicopters require some skill to fly, even take off without crash.

I'll probably reduce the number of engines to two rotating opposite to compensate for torque.

I've seen pictures of a quad heli used by the German police as "flying eye". It is driven by four 30ccm two-stroke engines and can accept quite some payload as a complete TV-camera with real time image transmission to the ground station and all the remote controls for flight maneouvers and camera operation.

Boncuk

 

[dknguyen]

Helicopter has one safety feature that a plane doesn't have though...a helicopter won't let you get off the ground if you can't land it...not so with an airplane! (If you can fly a helicopter you can land it, but you can fly a plane without being able to land it).

 

[Mikebits]

Helicopter has one safety feature that a plane doesn't have though...a helicopter won't let you get off the ground if you can't land it...not so with an airplane! (If you can fly a helicopter you can land it, but you can fly a plane without being able to land it).

Where did you get this from? I was stationed on the USS LPH-11 (Landing Pad Helicopter) Ship. I once witnessed a CH-53 helo take off and at about a mile out it blew up. All crew was lost. Cause was undetermined.

We had many incidents like this, that were never announced to the public.

Me personally, I have been in one helo and it was quite cool, but I would not get in another one if I did not have to.

 

[dknguyen]

Have you ever seen an RC helicopter be properly flown around by someone who did not have the skills to land it? On takeoff, it goes up a foot, tips over and returns right back to the ground. If the pilot is skilled enough to properly get it off the ground they are almost always skilled enough to land it (not always elegantly though).

A plane on the other hand, almost anyone can get it off the ground and fly it around reasonably...until they have to land it.

 

[Sceadwian]

Mike what he means is as far as the skill required to take off and land goes a helicopter is much more difficult than a plane. He's right I've spent hours goofing off in a simulator, if you can take off, you can land. Any dip can floor the throttle in an airplane and take off, do the same thing in a heli when you don't know what you're doing and you'll be flying towards to ground at 100mph inside 20 seconds, if you even make it that far.

 

[Boncuk]

Any dip can floor the throttle in an airplane and take off, do the same thing in a heli when you don't know what you're doing and you'll be flying towards to ground at 100mph inside 20 seconds, if you even make it that far.

Remember: It's not the high speed which kills, but it's the sudden stop!

Boncuk

 

[Sceadwian]

dk, I've only ever flown on simulators, but it took me almost a week before I had a good solid hover and orientation control. Even on a PC screen those things are fun to fly.

 

[dknguyen]

THere's something satisfying about being able to do banked turns in a helicopter so it looks like as if it were an airplane.

 

[Sceadwian]

Those are easy, just turn off the digital servos in the tail fins, and blow up the fin size if it's adjustable. They handle just like a slow flyer, only... different =) I think heading hold gyro's are the worst thing to ever come to RC helicopters (for begginers) experts should be able to switch them on and off so they can get those rock solid hovers, but you really need to let the aerodynamics on the tail fin take care of itself when you're in forward flight. Keep that in mind if you don't have someone that has real heli experiance standing next to you the first time you try to take off. Don't try to 'over control' the heli.

 

[dknguyen]

I like heading hold gyros. THe motion carries over to flying a plane and actually using the rudder during a turn. Using the tail fins alone doesn't seem to allow you to properly make very sharp banked at low speeds.

 

[Sceadwian]

???
What are you talking about dk. Heading hold gyros will try to counteract any force (wind) on the tail fin. There is no smooth motion at all. Maybe standard gyro's. The only way you can do that with a heading hold gyro is to mix rudder in with the aileron?

 

[dknguyen]

There's a smooth motion if you make it smooth. It's more predictable. It only does what you tell it do do (especially while turning and flying with crosswinds). It holds the yaw during collective changes and it seems if you do a sharp banked turn at low speed, the weather vaning is not strong enough to soley correct for the tail.

THe only way I can think of to actually do artificial weather vaning is to have differential pressure sensors mounted on the tail to measure and have the gyro take that into account- then you get weather vaning at a speed independent of the strength of the wind or speed of the heli...but that can get unpredictable.