Sub 7kg with Movi M5

[henrysj]

So is it possible - has anyone tried and succeeded?

The sum of the parts and it looks just doable on a hexa frame with 6s 6000mah batteries but its really touch and go and in reality will probably just creep over 7kg by a few grams so might have to strip it back some more.

My initial thoughts are:

Gryphone Hexa frame 1300g - this is a bit of a luxury as there are hexa frames out there 300g lighter but I have to say I'm a sucker for this ones looks and design

Gryphone Power Dist Board 52g

WKM Flight Control 118g

Tmotor U5 x6 1020g

Tmotor 15" Props x6 138g

KDE 35 Esc x6 276g - might swap this for the Tmotor opto 40 pro and save 32g

6000mah 6s Batteries x2 1630g

Movi M5 fully setup including HDMI converter, cable, vtx, antenna, toad in the hole and battery 2002g - can loose the camera mount top bar & toad on this saving a few more grams

Which leaves me at the moment with about 500g for camera - black magic pocket + non zoom lens.

I wouldn't have any landing gear and just use a box for take-off & landings although I still need to find out if this is okay with the CAA



Any thoughts / recommendations would be appreciated

 

[baja-king]

Hi Henry,

I think that you would be better going for a safety case with the Skyjib than trying to get the movi to work on a sub 7kg machine.

Chances are that if the CAA see everybody heading down the sub 7kg route they will change tack and move the goal posts again :upset:

I'm sure you could do it but it restricts your choice of camera and lens to much for me.

Love the Gyphon frames, building an X8 as we speak.

 

[jes1111]

I've been searching the available documentation for an answer but cannot find a clear statement: does the 7kg limit include battery/fuel? The 20kg limit definitely does NOT include battery/fuel.

 

[baja-king]

I've been searching the available documentation for an answer but cannot find a clear statement: does the 7kg limit include battery/fuel? The 20kg limit definitely does NOT include battery/fuel.

7kg including battery, as [MENTION=3211]Benjamin Kenobi[/MENTION] stated correctly the batteries are considered as fuel tanks and the electric current is the fuel...

 

[jes1111]

7kg including battery, as @Benjamin Kenobi stated correctly the batteries are considered as fuel tanks and the electric current is the fuel...

Yep - I can find statements from private individuals, but I cannot find anything in the CAA documentation that confirms this. Furthermore, I can see no valid logic in classing a Lipo as a "fuel tank" and the "stored charge" as the fuel. Given that the regulations are aimed at safety and 7kg has been chosen as a division point in terms of the "injury/damage potential", why allow a liquid fuel powered aircraft to carry an unlimited/unregulated amount of fuel beyond its 7kg "dry weight"? Just doesn't make any sense.

 

[baja-king]

Logic - CAA

 

[henrysj]

Hey Steve,

If I could stick with Skyjib I would love to but judging from what I hear about CAA & response times I think not having a sub 7kg RPA in the stable will just be too limiting. Partly the reason why I'd like to go for the Gryphon frame so its easily upgradable once thee CAA sorts their act out. I quite agree though it does limit camera & lens too much and trying to squeeze it in under 7kg is only going to effect the safety of the rig.

Are you planning on holding onto your Skyjib too or just moving onto the Gryphon? Looking forward to seeing some pics of it - any complaints about it so far?

 

[jes1111]

Logic - CAA

Yeah - this smells to me like an on-the-fly interpretation by one individual at the CAA. To my mind, unless the ANA clearly states otherwise then the battery packs (being the direct equivalent of "the fuel") are not included in the "7kg (without fuel)" definition. Furthermore, if the ANA is amended to reflect this daft interpretation then it should be challenged! The only fair and logical alteration of the ANA should actually be to include a full liquid fuel load when assessing the weight of non-electric aircraft. Otherwise their claim of 7kg representing any kind of meaningful threshold doesn't hold water (pun intended).

 

[baja-king]

Yeah - this smells to me like an on-the-fly interpretation by one individual at the CAA. To my mind, unless the ANA clearly states otherwise then the battery packs (being the direct equivalent of "the fuel") are not included in the "7kg (without fuel)" definition. Furthermore, if the ANA is amended to reflect this daft interpretation then it should be challenged! The only fair and logical alteration of the ANA should actually be to include a full liquid fuel load when assessing the weight of non-electric aircraft. Otherwise their claim of 7kg representing any kind of meaningful threshold doesn't hold water (pun intended).

Would be worth a go I challenged Andre at EURO USC about it and he said the same as @Benjamin Kenobi

 

[henrysj]

Same with Resource Group - according to them batteries are included in the 7kg

 

[baja-king]

Hey Steve,

If I could stick with Skyjib I would love to but judging from what I hear about CAA & response times I think not having a sub 7kg RPA in the stable will just be too limiting. Partly the reason why I'd like to go for the Gryphon frame so its easily upgradable once thee CAA sorts their act out. I quite agree though it does limit camera & lens too much and trying to squeeze it in under 7kg is only going to effect the safety of the rig.

Are you planning on holding onto your Skyjib too or just moving onto the Gryphon? Looking forward to seeing some pics of it - any complaints about it so far?

If you have an agreed safety case for a 7-20kg rig you will not have to apply to the CAA for exemptions to fly in congested areas AFAIK - that's the point of a safety case

Skyjib has been sold, will post pics of new rig soon. The Gryphon frames are amazing, so well thought out...

 

[jes1111]

Same with Resource Group - according to them batteries are included in the 7kg

Sorry - what's the "Resource Group"?

If this distinction is not actually written into the regulations then it holds no validity. As is so often the case in government matters, personal interpretations are laid on top of ambiguous/meaningless regulations and propagate as "fact" when they're not. The CAA must clarify this within the legislation. Logic and common sense dictate that it's the liquid fuel exclusion that should change, not this absurd interpretation of a battery. If the CAA are happy that a 7kg aircraft with an additional, say, 3kg of liquid fuel is within this "safer" category, then they should also agree that a 10kg electric-powered aircraft is comparable. I'd defy them to present a valid argument that this shouldn't be so.

 

[henrysj]

It's the only other company in the UK where you can get ur CAA RPAS qualification.

I quite agree with you it makes no sense that a 7kg with 3kg of fuel is any different to 7kg with 3kg of lipos but if both CAA credited training schools are teaching this and I know they get quizzed a lot on this fact with pilots coming through the course then it's gotta be being enforced by the CAA.

Am always up for challenge though... Where we signing?!

 

[henrysj]

If you have an agreed safety case for a 7-20kg rig you will not have to apply to the CAA for exemptions to fly in congested areas AFAIK - that's the point of a safety case

Skyjib has been sold, will post pics of new rig soon. The Gryphon frames are amazing, so well thought out...

That's good to know. I thought it was on a per job basis that you could apply for an exemption only

 

[PMaughan]

Sorry - what's the "Resource Group"?

If this distinction is not actually written into the regulations then it holds no validity. As is so often the case in government matters, personal interpretations are laid on top of ambiguous/meaningless regulations and propagate as "fact" when they're not. The CAA must clarify this within the legislation. Logic and common sense dictate that it's the liquid fuel exclusion that should change, not this absurd interpretation of a battery. If the CAA are happy that a 7kg aircraft with an additional, say, 3kg of liquid fuel is within this "safer" category, then they should also agree that a 10kg electric-powered aircraft is comparable. I'd defy them to present a valid argument that this shouldn't be so.

It does mention in here on the CAA website: http://www.caa.co.uk/default.aspx?catid=1995&pageid=16011

Have to say the CAA is pushing the safety envelope before the tech can produce a good quality camera rig with redundancy at 7kg. It's close but not there yet, 8Kg would do it I think...

Pete

 

[PMaughan]

Perhaps the ARPAS guys are able to put some pressure on the authorities to lift the 7kg limit, is 7kg just an arbitrary weight or based on some clever maths that 7.5 or 8kg mass has an exponential effect when it hits the dirt??

Promise I'll join ARPAS when I claw back some funds from this venture...

Pete

 

[jes1111]

It does mention in here on the CAA website: http://www.caa.co.uk/default.aspx?catid=1995&pageid=16011

Have to say the CAA is pushing the safety envelope before the tech can produce a good quality camera rig with redundancy at 7kg. It's close but not there yet, 8Kg would do it I think...

Pete

Thanks for finding that - but it is still only an "informational statement" not actually written into the ANA and therefore not part of the enforceable regulations as far as I'm concerned.

You're right, of course - 7kg is a really awkward weight limit for a camera ship. That's why I'm kinda interested to see this clarified and legitimized. It's nuts to penalise the cleaner, quieter technology over the noisy, polluting alternative.

Perhaps the ARPAS guys are able to put some pressure on the authorities to lift the 7kg limit, is 7kg just an arbitrary weight or based on some clever maths that 7.5 or 8kg mass has an exponential effect when it hits the dirt??

Promise I'll join ARPAS when I claw back some funds from this venture...

Pete

My guess is it's arbitrary.

[h=2]Electrically Propelled Aircraft[/h]Take note also that for electrically propelled aircraft, the battery itself is considered to be a part of the aircraft - it is the battery's charge that is the fuel. The logic for this is that the battery is basically the 'fuel tank' or, in other words, when the battery has run out of fuel, it still weighs the same.

Only a civil servant could dream up such a ridiculous, smug interpretation and be so proud of it that he fails to realise that it makes a nonsense of the 7kg distinction. :livid:

 

[jes1111]

My next build is going to be a sub-7kg turbine-powered, belt driven multirotor with a HUGE fuel tank - should be easy to get to a take-off weight of around 30kg But, of course it will be MUCH safer than a 7.1kg electric machine.

 

[Bowley]

Perhaps the ARPAS guys are able to put some pressure on the authorities to lift the 7kg limit, is 7kg just an arbitrary weight or based on some clever maths that 7.5 or 8kg mass has an exponential effect when it hits the dirt??

Promise I'll join ARPAS when I claw back some funds from this venture...

Pete

The 7kg threshold is somewhat historical going back to the days when when the CAA would accept a BMFA certificate for issue of PFAW,

 

[Benjamin Kenobi]

Well, there's got to be a limit. Why is the motorway speed limit 70mph?

I'm sure it was from an analysis of mass and acceleration and the impact on a human body.

If we push the 7kg thing too much they'll take that away too.