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To tri or to T? That is the question

Toddy

Junior Member
#1
So here's my dilemma. Way too much reading and not enough flying.
My only experience with multi rotors is my blade MQX. I have been reading everything I can find on the subject and have decided on the tri design. From those of you with the experience behind you which of the two are more learner orientated, in other words take a beating and come out less scathed than the other?
I have all the parts ordered and am just waiting for them to arrive on the slow boat from Hong Kong. While I have been waiting I have been busy building frames, now I have two of David's designs from rc explorer, his normal tri copter shape and also the coffin shape for bit extra room, both with 48 cm booms. Then I got thinking and and had to make a 28" T copter frame to complement the other two. So of coarse now I don't know which to build up and actually fly or attempt to anyway.
Build items on there way are:
L2210c 1200kv motors x4
25 amp plush ESC's X3
KK2 FC
9X4.7 props X18 ( just incase )
I'm sure you have all been in my shoes before and know what I'm going through so all and any advice is always apriciated.
 
#2
David's tri design would probably lend it self to a little more abuse. The folding arms and use of zip ties lend them selves to absorb energy with collisions into earth based objects. A rigid T design could have less malleability and cause more work in repairs.

Shorter booms will also tend to be stronger and less suseptable to lever force on impacts. From my observations, 10-12" or 25-30CM booms seems to do well.
 

Toddy

Junior Member
#3
Thanks mustang, did consider shorter booms but being very new to the tri copter thought that the extra length might give me more stability, would twelve inches still give the stability? He T copter design I have built has zip ties holding the front T in place, got the idea from Hallstudio (YouTube) simple copter design so in effect works like the tri copter and by the video of the simple copter when he ditched it the arm did break the zip tie and fold back. See what I mean, one minute I've got it sorted then I go and confuse myself again LOL....
 
#4
I would suggest the shorter 30CM booms on the RCExplorer body and the longer 48CM booms in a T configuration with the coffin body. Let the shorter arms fold and the longer arms break away. It takes less force on a longer arm to break away than it does on a shorter arm; remember you're looking to dump energy away from your hardware.

I personally would build the Y tri first.
 

IBeHoey

The Warranty Voider
#5
You really can't go wrong with either design, but I, for one, love the T-copter design and personally think they're easier to build. For my arms, I used some 1/2inch (roughly 12mm) wood dowels that I got from the hardware store, and then cut out a square piece of 1/4inch ply to mount the electronics to. I then use small screws and gorilla glue to hold everything together. Strap the motors/Esc down with zip ties and you're good to go. If you're worried about making repairs, hold off on putting the gorilla glue on the front arm and just use a few screws instead. In the event of a hard crash, resulting in a broken arm, just unscrew and replace. Minimum downtime.

I've played around with different motor-to-motor lengths, and for my setup using 24g blue wonders, 17.5inch (440mm) spacing gave me the perfect balance of stability/maneuverability. 12inch spacing was fun, but it could also be a handful at times.

I don't have much experience with a Y tri, so I can't really comment on flight characteristics but 100ft up, I believe the T design would be easier to keep track of than a Y design.
 
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colorex

Rotor Riot!
Mentor
#6
My personal recommendation is to get a quad instead of a tricopter. I dislike the constant fixing of the yaw mechanism. Of course that depends on how you're flying. :D
 

Toddy

Junior Member
#7
Awesome responses thanks guys. I'm coming to the conclusion that it really comes down to looks with the tri or T design. I must admit the T does look rather cool and I do like the idea of being able to put the ESCs in the body and not zip tyed onto the arms. Will have to get all the ESCs and FC sorted out then make up my mind.
I can understand the reason for staying with the quad but I like the way the tri's look when they are in the air. As with anybody getting into multi copters I could possibly change my mind. Then again I could always have one of each or so. ....
 
#8
As far as FC goes do ur reaserch lol all of them are pretty good but some are way harder that others for pograming and tunning
 

Cyberdactyl

Misfit Multirotor Monkey
#9
I agree with colorex . . .IF you just want to get flying as soon and easy as possible, build a quad.

However, tricopters and t-copters are more fun. Now I agree and disagree with Mustang. IF you merely build a "Hallstudio" type T-copter, it will probably break a bit easier than the folding arm design similar to the David W design. But there are a few very simple things you can do to a t-copter to greatly increase the ability to absorb energy in a crash and become an equal, or exceed, a tricopter in regards to crash survival.

First is to use the infamous smaller nylon ties. As I'm sure you've read by now, they are invaluable for new flyers. They will fail before motor mounts, saving you a lot of money. Second, use cheap plastic props. You break'em, you're out a buck or two. Third, DON'T screw into wood booms. Especially at high moment points.

I'm not going to draw the whole T-copter, but this will get the idea across. Purchase "Fat Boys" O-Rings. You then put the screws that will clamp the booms and hold the plates together through three or four stacked Fat Boys between the plates, insuring three or millimeters of gap between the screws and the booms. When you tighten the screws, using lock nuts or loctite (blue), don't over tighten. You want enough clamping pressure to hold the booms snug, yet loose enough the booms are allowed to move a bit during a hard impact with the ground. Not only do the O-rings absorb energy when the boom accelerates into the screws, the booms are allowed to pivot around the outer screws (dashed lines). Depending on the layout design, you could very well get away with only one bump screw at the intersection of the three booms.

I used a variation of this on my quad using 90mil EPDM rubber, and I'm sure it saved me changing booms several times in my first few weeks of flying. Now I DID break booms twice, but those were HARD crashes.

 
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Toddy

Junior Member
#10
Thankyou for sharing your design Cyberdactyl, it is very good of you to share your experience in building with everybody.
Much apriciated.
 

IBeHoey

The Warranty Voider
#11
Third, DON'T screw into wood booms. Especially at high moment points.
Any particular reason for this? I can see it being an issue if you were to directly screw (without drilling a hole first) into the boom, and then use some fairly large screws. I ask, because I've been using screws on my T frames for awhile now and have yet to have an issue. This one here being one of my more recent frames using 1/2inch wood dowels.
TC_v3_1.jpg

I have one screw going through the middle to attach the front arm to the rear boom, and then 2 on top to secure it to the plate. I fly this tri pretty hard and crash it almost daily. Thus far, the only repairs I've had to make are replacing several zipties, and a handful of props. Should the day come, and I actually break an arm, I'll just undo those 3 screws, replace the arm, then go. It's a real simple setup, takes hardly anytime to build (most of which is just waiting for the gorilla glue to dry), and it's dirt cheap.
 

Cyberdactyl

Misfit Multirotor Monkey
#12
It greatly weakens the booms.

But, if you don't crash and acutely stress the boom, it's not a big deal. Similarly, if you don't crash, there's no need to use zip ties.
 

dockman

Junior Member
#13
Wood booms are cheap, other than zip ties the booms are my preferred thing to break. And I have def had some booms break from my sideways landings at speed!
 

Cyberdactyl

Misfit Multirotor Monkey
#14
Its really just comes down to a 'best practices' attitude.

For little additional effort, several aspects of a design can be greatly enhanced.

When it comes to multirotors, one of the design elements should also consider experience of the pilot and flight control system, and those two's integration. In simple terms, how can one best modify and/or design a frame to best prolong the experience without repair, or at least minimal repair.

The zip tie, lightly clamped booms, a shrouded FC, cheap props, extending the boom past the motor the radius of the prop, is but a few of the examples to emerge.
 

xuzme720

Dedicated foam bender
Mentor
#15
Its really just comes down to a 'best practices' attitude.

For little additional effort, several aspects of a design can be greatly enhanced.

When it comes to multirotors, one of the design elements should also consider experience of the pilot and flight control system, and those two's integration. In simple terms, how can one best modify and/or design a frame to best prolong the experience without repair, or at least minimal repair.

The zip tie, lightly clamped booms, a shrouded FC, cheap props, extending the boom past the motor the radius of the prop, is but a few of the examples to emerge.
Maybe you can look at it like this: not "what's best" but "what's best for me"...
We are all going to change it so it works for us.
 

IBeHoey

The Warranty Voider
#20
Can someone post the plans for the Tcopter? Thinking of switching from y to t design
Woo another Tcopter convert! :D

Here's a link to a thread that I found to be very informative when I was building my first tcopter.
http://www.rcgroups.com/forums/showthread.php?t=1309716

and, here's a link to a tcopter dimensions calculator that someone put together. This is real handy as it shows you where the proper CG should be. http://lloydhassell.brinkster.net/rcgroups/t-copter%20dimensions%20calculator.html

I've also been slowly working on a build article (that I hope to have finished in the next week or so) of a 600mm sized tcopter that I've built around the DT-750 brushless motors. It's the first build article of any kind that I have ever done, so I'm unsure on how helpful it'll really be BUT there's going to be a ton of pictures. :D
600 T-Copter.jpg
Anywho, good luck with your build and be sure to share some pics of it when you're done.