payload mounting options

m00se · Apr 22, 2015

hi guys,

I have to "TRY" and mount about 600g on the inspire one,
I have tried a few options over the last few days, and what I have come up with is below.
The way I see it, any weight that you add to the body would need to be lifted and lowered by the servo during transformation, and any weight added to the arms, would in fact at least not stress the servo any more than normal.

Can anyone think of any reasonable reasons to not mount the payload as per the pic below?
I have left a channel on the inside of the semicircular mounting point, allowing me to glue some rubber in there to add some grip, and then the three channels that can be seen will hold cable ties to secure it to the arm.

the two seperate payload "bays" are keyed at the union with dowels and holes that should help keep them on the same level and add some support.

InspiredOne · Apr 22, 2015

m00se said:
The way I see it, any weight that you add to the body would need to be lifted and lowered by the servo during transformation, and any weight added to the arms, would in fact at least not stress the servo any more than normal.

Probably being the last person here who should reply... I'm having a hard time seeing any difference in the two situations given above.

Anything attached to the arms will have to lifted by the servo whether or the ground or in the air when the gear are retracted. Right?

The Editor · Apr 22, 2015

Got me thinking this one.....I would postulate that a given mass is already lifted airborne by the motors.
Your all up weight (AUW) would comprise of the Inspire plus the additional payload and therefore the thrust necessary to lift off and hover would be constant.
By retracting the servo for the landing gear, the craft would simply move its position in 3d space (altitude) to compensate. So in other words, the height of the rotors would remain more constant than usual with the body of the Inspire dropping slightly. In theory the flight controller would adjust the attitude of the craft to take into account the additional mass of the payload.

But I have to ask...... What are you hoping to lift?

Here's an Inspire lifting over a kg but unfortunately no transformation to see how it behaves.

InspiredOne · Apr 22, 2015

T.E., I read your post a few times trying to remember how the landing gear were retracted. Finally, I took the copter our front, lifted off and retracted the gear. Actually, the body remains in place and the gear (arms, motors, etc.) are lifted above the stationary body.

That being the case, wouldn't the servo be required to lift the extra 600 grams?

The Editor · Apr 22, 2015

InspiredOne said:
T.E., I read your post a few times trying to remember how the landing gear were retracted. Finally, I took the copter our front, lifted off and retracted the gear. Actually, the body remains in place and the gear (arms, motors, etc.) are lifted above the stationary body.

That being the case, wouldn't the servo be required to lift the extra 600 grams?

That's what I'm trying to get my head round

Thinking about it again, you may well be right. The Inspire would try and maintain it's height during transformation so possibly the retract servo would be put under unnecessary strain while the motors would remain outputing their original thrust...........I think!!!!!

InspiredOne · Apr 22, 2015

Yeah, this is a tuffy! Pure guesses on my part.

NOTE: I am not an engineer in any way, shape or form--aeronautical or mechanical or any otherical.

The Editor · Apr 22, 2015

There will be a rocket scientist along shortly........

m00se · Apr 23, 2015

The Editor said:
There will be a rocket scientist along shortly........

I cant wait to hear his opinion,

The way I see it, the motors will obviously always be under more strain from any mass increase. But think of it like this, the servo can clearly lift the Body weight of the inspire, it has to do so when going into travel mode, if you were to hand the inspire from the motors with string, then lower or raise the gear, it would be lifting the body.

mine definately does not maintain altitude in any way, shape or form during transformation, it always gains a few m when gear is put up and loses a few when gear comes down, so its hard to say if the body moves or the motors do.

I dont neccesarily have to transform, the flights could be made with the gear down, infact I will be flying low, so would probably opt for that anyway

skylabimaging · Apr 23, 2015

You'll drop flight times...motors are designed to carry 3200g, and according to DJI the i1 is 29--and some change. so essentially you'll be adding on an extra 300g which doesn't seem like a whole lot more.

How this affects the lift system is another story, I don't know what thats rated for but all you'd be doing is shortening it's lifespan, it may only work one time it could work a thousand times over, there's no way of answering the question without knowing what servo DJI uses to lift the booms, I would imagine for endurance purposes it's over torqued anyway so it doesn't wear out as easily.

m00se · Apr 23, 2015

is the 3200g figure including the prop configuration and the 6s on the inspire?

sirnikolas · Apr 23, 2015

Can we ask what you are lifting?

m00se · Apr 23, 2015

nothing fancy, but it is technically a little secret....... lol

I have flown half the required payload with a ductape harness hanging from the arms, and noticed a lot of oscilation on the airframe due to the ability of the payload mass to shift during flight, hence the quick and dirty 3d printing of a rigid container

skylabimaging · Apr 23, 2015

m00se said:
is the 3200g figure including the prop configuration and the 6s on the inspire?

i1 was designed around the e800 lift kit..which was built to lift 800g on 13in props on a 6s motor...so yes.

m00se · Apr 23, 2015

ok, so it will taking it out of spec by about 300g........ will have to do some testing to see what effect that has on stability and flightime

skylabimaging · Apr 23, 2015

If the gains have a large enough margin those will help with oscillation, and the weight is marked with the tb47...it will be different with a tb48. Either way you cut it, wrong platform to carry a payload, just my opinion but I understand you gotta work with what ya got.

m00se · Apr 23, 2015

I agree about being the wrong platform to carry a payload, Im well aware of that, but out of the ones I have , its the one with the highest chance of success in the environment in which I have to fly,

I might stick some fpv on the phantom and try that