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Tricoptor, quad or H ??

#1
Hi guys.
Summers looming down here.
Im considering selling the unbuilt 450 heli kit I have & building a Multi . The heli is almost a full time thing to learn, a multi would be easier to learn to fly & still have time to fly my planes. I have flown one of the small toy quads, allmost too easy . Are the bigger quads just as easy to fly as the small toy quads ??
How do multi's compare to learning to fly a 450 heli ?? Im guessing alot safer as much smaller blades , so quads could be flown in public parks .

What are the differnces between the tri, quad & H , flight wise.
Is a tri OK as a 1st real multi ??
Just how expensive are the crashes, with the FT kits I guess its mainly replace wooden booms & props or do they get totaled on crashes ??

Cheers
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#2
V-tail.

For flight characteristics, Quads and H's aren't really different at all. You see a different frame, but the props see no difference at all. The H gives you a better/bigger center platform for gear and easier forward mount for cameras.

Big difference between the quad and tri -- Yaw response. Physics will limit yaw on quads, and a *lot* of yaw in flight will put more heat/drain on the power system (has to spin up one pair and spin down the other -- a little is ok, a lot isn't w/o consequence). A tri has a fantastic yaw response because of the trust vectoring on the tail. Makes for fairly swooshy flying.

A V-tail is right inbetween. The tail motors are canted left/right to slightly oppose each other, and yaw is achieved by changing this imbalance -- far more powerful than the quad, but always wastes a little energy opposing each other. the angle of the motors is the tradeoff between wasted thrust and snappy yaw-- at ~40 degrees you throw away ~25% of thrust, at 20 degrees, you throw away 6%. My booms are set at 20 and the yaw is very strong, but others may want more.

IMO, of the three, the V-tail has the best response for the fewest moving parts -- servos are way too easy to break on tri's and while quads are slightly more efficient, their flight profile is, well, flat.

There are rare cases you can "total" a multi *frame* -- the derilin FT uses is resilient, but not unbreakable. most of the reports I've heard say it happens consistantly on crashes on hard surfaces(asphalt/concrete/gravel), while it does bend and pop apart under softer crashes (dirt or grass).

booms will be broken, but they're cheap assuming you've got a way to cut and drill wood booms. Aluminum is heavy, transmits vibe badly and will bend in a bad crash. CF is pretty strong, but hard t source and fairly fragile to shock. If you've got access to some plastics, with the right types you can make more resilient booms, but I don't know a good commercial source for anything other than the full sheets, which then have to be cut into strips.

Props should be counted as consumables, like batteries. You might keep a set around for a while, but don't expect it to last -- have *many* spares on hand, especially when starting off. For fixed wing I'd recommend getting a nice but not the nicest props -- not multis. Buy cheap but not the cheapest props -- you will break them. regularly.

Electronics usually survive -- Tail servos are the most common failure among that set, motor shafts are next.

As for a 1st multi, w/o heli experience go quad, w/ heli experience go V-tail -- more responsive, fewer parts to break.
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#4
Oh, noticed I hadn't hit al your questions.

true for pretty much every type of model craft:
smaller = potentially less damage to itself and others, but harder to control (twitchyer and more susceptable to wind)
larger = more dangerous, but more control over stablility

Quads need space, so don't fly one in a crowded park, but if you've got open space and joggers on a trail around the edge, you might get away with it safely. just don't hesitate to land/ditch and go somewhere else if the conditions weren't what you thought they were or the conditions change (like the pee-wee football team arriving to play).

As for relitive stability compared to helis, it depends on the heli and the control board. the analogy I like for helis:
- coaxials are like ballancing a marble inside a basketball. Super stable but won't do much of anything
- fixed pitch are like ballancing inside a beach ball. Very stable, but with a little work you can get it to do a little bit more
- CP hellis are like balancing on top of a beach ball. it can be done, but the only easy thing to do is crash.

For multis, the properly set-up control board sets where it lands
- control boards w/ good tuned self level (gyros and accelerometers) -- like flying on ice. The marble is now on a flat sheet -- it weill go where you point it, but continue when you go hands off.
- control boards w/ good tuned acro (gyros only) -- somewhere between ice and top of beach ball. you still have to balance the platform, but when well tunrd it's not that hard.
- control boards w/ all the bells and whistles (gyro, accelerometer, barometer, compass, GPS, cupholder . . . ) -- you're back to coaxial stability with a touch more control lattitude. It's good for photography or the noob uninterested in learning to fly, but a VERY synthetic experince.
 

kah00na

Senior Member
#5
When I was deciding between a quad and tri, I watched YouTube videos to see if I could tell any flight characteristic differences between them and decided that I really liked the way Hall Studio flew his and his skill level didn't see too far out of reach (he is really good!) and that convinced me to go with a Tricopter. It's true that the rear servo is one of the first things to break in a crash - I'm on my third one and it is the most difficult part of building one. However, after flying my tricopter for over 9 months, I finally flew a full sized quad copter and noted the yaw was noticeably slower. Some people, like Warthox, can get great yaw (unbelievable yaw) out of quads, but I couldn't. I'm very happy with my tricopters. I was also able to save the cost of a 4th motor and ESC!

The most damage I've done in a crash is cracked one of my frames. It cost about $8 to fix. $4 for 1/2 arms + $4 for 1/8 inch plywood. I fly with some foam over my electronics to protect them so I haven't had to replace any of them yet. The servos I've been using are digital metal gear servos for about $8 from banggood.
 
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Cyberdactyl

Misfit Multirotor Monkey
#6
I can't add any better advice that Craftydan hasn't already shared, other than tricopters are probably the most fun to fly and provides the most "feel" of actually flying.
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#7
I can't add any better advice that Craftydan hasn't already shared, other than tricopters are probably the most fun to fly and provides the most "feel" of actually flying.
been a slow morning for me . . . lotsa time to yammer on and on and on . . . .
 

Johan

Senior Member
#8
been a slow morning for me . . . lotsa time to yammer on and on and on . . . .
Maybe yes, but providing a very interesting read with great analogies (the marble / beach ball thing), providing an almost tangible comparison between all flavors of multirotors :)
I'd say: a must-read for starting multi-rotorists (can't imagine that is a word, but then again I'm Dutch :))
 

xuzme720

Dedicated foam bender
Mentor
#9
Maybe yes, but providing a very interesting read with great analogies (the marble / beach ball thing), providing an almost tangible comparison between all flavors of multirotors :)
I'd say: a must-read for starting multi-rotorists (can't imagine that is a word, but then again I'm Dutch :))
I think if it's not a word, we'll just adopt it as one because it's perfect.