My Scratch Build H-Quad (design by Flite Test)

[Hands0n]

I decided to give it a go, as they say.  While learning the basics of flying using a RTF F450 clone, breaking it, repairing it, trying different FCs I picked up a bit of an itch to try my hand at building one also.  Why not?

I';ll probably end up with a small fleet of the things - I love to play with mechanics and tech, don';t do enough of it and this hobby has the great ability to mix both.   So while I was braining up on anything I could read or watch I came across the Flite Test lads on YouTube - quite an interesting viewing of their stuff, something for everyone if you ask me.

Anyroadup, I decided to give their Scratch H-Quad build a go - the video and links to the design plans are here https://www.youtube.com/watch?v=gh5zJQDKOSQ  -  and so far it has been reasonably plain sailing, well until about 30 minutes ago.

I used regular pine sourced from Wickes, it came out a bit heavy at 494 grams for the frame alone.  Adding the electronics brings it to 946 grams, and the 3S 11.1v LiPo brings it to a lumpy total of 1,138 grams.

Today, for its maiden flight, I used a HobbyKing 328P FC that I had left over from the F450 (that now has a MultiWii Pro, thank you Paul, its running lovely).

I don';t have any video of the maiden - must remember to do that in future - but it wobbles like a geriatric who';s been on the gin. The PIDs need some sorting out from their defaults (P was 3.2, I can';t recall the others).   I';ve cranked P down to 1.6, now back up to 2.0 but it still wobbles a bit, much less though.  During this time I and D have been zero. I need more time.

Unfortunately, time was taken away from me    I was running the quad in my hand, just trying to feel what the different P values were doing (I';ve been doing this successfully with the F450) when I lost my grip and it shot across the room, through the dividing wall window and trashed its props on the kitchen floor.  Back to eBay for me then!

The chaps at Flite Test used an APM 2.5 in theirs with stock PID and it flew like a charm. I may think along those lines later on. Right now this is all about learning the ins and outs.

When I get the new props I';ll pop up some pics and video of the outdoor attempts at stabilising the thing.

Now I';ve got to go re-read what I saw on this forum about best practise in setting up the PID from scratch.

[yama]

ha i found that you tube video today, after deciding to bosh together a h-copter out of fish tank spares yesterday. hope mine will fly as good as the test flite guys..

any pictures of your creation??

[Hands0n]

Hi yama - Here are a couple of pics of my H-quad complete with broken props.

It is currently sporting a HobbyKing 328P FC, 30A Red Brick ESCs and Turnigy 2231N 80KV motors

My plan is to pop in an APM2.5 (RC Timer) to see if I can get it to fly stable - it absolutely hates the 328P FC. Wobbles like a fat bird at the disco ten minutes after the music has stopped.

[yama]

just a thought, i might be talking rubbish as i dont even have a working quad yet, but arent the FC meant to be central on the aircraft? could this be causing your wobbles?

[guest325]

just a thought, i might be talking rubbish as i dont even have a working quad yet, but arent the FC meant to be central on the aircraft? could this be causing your wobbles?

You';ve hit it on the nail there - the FC should be positioned on the centre of mass of the model, where it is it will be continuously fighting to get things stable. Find the centre of mass without the board then fit it over that point and try it again - should work!

[Gaza07]

+1 your controller deff needs to be in the center and the copter should be balanced with the battery 
also what is holding your flight conttoller down is it velcro ? I ask because velcro will allow it to wobble 

[Hands0n]

Ah, good spot gentlemen.  Absolutely correct on all counts.  I didn';t think about centre of mass  - that makes complete sense to see it in print of course  . And yes, I did use velcro and foam to cushion against vibration.  The battery was positioned in front of the power distribution board to help even out the weight distribution, with it installed the board balances near-perfectly. 

A bit of adjustment coming up methinks. Good thing its all in wood.

It was an impressive maiden though - looking like that flying aircraft carrier thing in The Avengers - a bloody great behemoth lifting off the grass in my garden and casting massive shadows over the area 

[Hands0n]

Here we go Ladies and Gentlemen - This is the second flight made with the H-Quad Scratch Build - the YouTube link is at the end of this post.

Taking the good advice given here I have re-positioned the FC to dead centre of the H-Quad.  But I have done nothing else to it since the maiden flight.  In that flight I had made some serious PID adjustments in my attempts to stabilise it. Fruitlessly I may add.  I was just keen to see if it would fly any better - and it did  So thats okay then.

Although quite wobbly in places, and trying to handle a fairly light and inconsistent breeze, the H-Quad alternated between fairly stable to "a bit of a wobble".  But at no time did it actually feel out of control.  Either that or I';m learning to fly incredibly odd aircraft  ::) dooming me to never being able to fly anything "normal" 

The next time out - probably Friday - I will do some work on the PIDs to iron out the lumpy bits. Once I';ve got it sussed out I';ll have to give the old girl a bit of a paint job.

So, have a look and let me know what you think.

Flight video (3:48) http://youtu.be/tbkDIMoDcDQ

[guest325]

Looks much more stable than before, few PID tweaks and you';ll be cooking on gas!!!

[FlyinMarty]

It certainly flies, nice one...must be a great feeling to build from scratch and get it in the air.

[Hands0n]

Cheers fellas. It really is a splendid feeling to see it fly. I';ve not scratch built anything for a couple of decades! Its nice to get back into it with something so completely different.

Sent from my C6603 using Tapatalk 4 Beta

[JT]

 Nice job there!  Must be nice to see something you';ve built fly. 

Just a thought and may not be relevant(as you may have already done this) but I had a hell of a job trying to get the wobble out of my multiwii f450 clone, I ended up with the P at well under 2 and it still wobbled. I had read somewhere that the simonK ESC firmware could help as some ESCs are a bit slow to react for multirotors and so flashed my ESC';s with it. It sorted everything out instantly, my P is now 4 and in level its 16 and super solid with no sign of wobble. It might sort yours out.

[Hands0n]

@JT - ah, thanks for that tip. I';ve reset the PID to the default for the 385P last night, but didn';t have enough battery to re-test it. Thats tonight';s bijoux task. 

I';m running Red Brick ESCs - and believe that there is a SimonK image for them.  A programming clip is on order with HobbyKing so once it arrives I';ll certainly do that as a matter of course.   

It';ll be good to get the behemoth super stable.  Thinking of pimping it up once I';ve got the technicalities out of the way 

[davidnclare]

Looks great, make a not of your PI term so you can go back to them.
I think setting the PI terms with auto level off gives the best results.
Well done.

[jimbo385]

Great job!

[Hands0n]

Thank you ::)

I had planned to work on it today during my day off but got sidetracked repairing my 450 mostly. So the plan is to spend some time on the H on Saturday. I';ve defaulted all the FC';s settings. Will start by lowering the P and zero I and D as it is still quite wobbly. I';m never certain how much to vary these by when making adjustments.

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