Size Limitations for Multirotors

[Dave Hopkin]

As a Club renting a flying field from the council we have to have size limitations on models, we have the following sizings

All Models limited to 7Kg

Fixed Wing Max power 1.60cu/23cc IC or 2800W electric

Helos - 1500mm Rotor Diam and 0.60cu/10cc or 1500W Electric

Multirotor -------- We dont have a clue!!

Anyone give me some guidance!!!

[Biggles' Elder Brother - Moderator]

In terms of commercial licence classifications the break points of 7Kg and 20Kg MTOM (Maximum Take Off Mass) have been used. Fits well with the FW regs - it's what our club effectively uses.

Fundementally size isn't really the issue here - its energy that is the issue. And energy is primarily determined by mass and speed, so a weight limit rather than size limit does make some sense - it's what CAA use.

BEB

[Dave Hopkin]

7Kg for a MR seem pretty damm enormous though!!

Edited By Dave Hopkin on 03/08/2017 18:38:20

[Denis Watkins]

I think Dave, some consideration has to be given to an MR having a " buzz saw " at each corner

But the guidelines of a planned flight, backed up with a spotter, and in line of sight

Go someway to limit the MRs flight to a safe margin

And has been said, 7kg, 1.60, 22cc, and a 60/1500w rotor are more easily quantifiable

I watch with interest, as you boffs will surely sort this meaningful quandary out.

One avenue, as a starting point could be "duration" as already some inroads have been to a 15 minute duration of models, due to their size and weight, and a fly away of any such beast could be catastrophic.

My vote would be "duration" which will cause some squabbling but 15 minutes is a good start point imo

Edited By Denis Watkins on 03/08/2017 19:38:14

[Dave Hopkin]

Posted by Denis Watkins on 03/08/2017 19:32:02:

I think Dave, some consideration has to be given to an MR having a " buzz saw " at each corner

But the guidelines of a planned flight, backed up with a spotter, and in line of sight

Go someway to limit the MRs flight to a safe margin

And has been said, 7kg, 1.60, 22cc, and a 60/1500w rotor are more easily quantifiable

I watch with interest, as you boffs will surely sort this meaningful quandary out.

Spotters are only mandated with FPV and not restricted to MRs

[Denis Watkins]

Ah but, I would approve spotters with either, FPV or otherwise, with line of sight

And if I had the guts, I would approve 10 minute model duration

With concentration being a factor as well as good manners allowing others to fly at a busy field

Edited By Denis Watkins on 03/08/2017 19:42:49

[Dave Hopkin]

Posted by Denis Watkins on 03/08/2017 19:39:49:

Ah but, I would approve spotters with either, FPV or otherwise, with line of sight

And if I had the guts, I would approve 10 minute model duration

With concentration being a factor as well as good manners allowing others to fly at a busy field

Edited By Denis Watkins on 03/08/2017 19:42:49

LOS is a legal requirement anyway - so we dont need to club rule to that effect

We allow 6 models in the air at the same time so we dont really need to specify a time limit (though if that does become an issue we would address it then)

[Pete B]

For MR's with GPS, it's easy enough to geofence the MR to a set radius from take-off point, say 200-300m. If the MR reaches that limit, RTH should activate.

A simple requirement for flying from a club site, perhaps?

Pete

[Dave Hopkin]

Posted by Pete B - Moderator on 03/08/2017 19:58:12:

For MR's with GPS, it's easy enough to geofence the MR to a set radius from take-off point, say 200-300m. If the MR reaches that limit, RTH should activate.

A simple requirement for flying from a club site, perhaps?

Pete

Not a bad idea but perhaps simplify it to Helos and MR restricted to 200yds from Pilot?

[Geoff S]

I'm quite happy to limit my flights to 10 minutes but I like to have a little time 'in the bank' to cover for unforeseen eventualities. The fuel tanks in my 2 petrol powered models allow me to have 2 flights, each of around 10 minutes, without refuelling and thermal soaring with an electrically assisted glider can be almost as long as you like in the right conditions (though I get bored after 20 minutes or so).

Setting a limit on absolute duration for either MR, helis or fixed wing isn't very practical though single flight time might be but difficult to enforce.

Geoff

[Pete B]

Posted by Dave Hopkin on 03/08/2017 20:04:18:

Not a bad idea but perhaps simplify it to Helos and MR restricted to 200yds from Pilot?

Manually, I suppose it's a subjective issue as to what is 200yds - opinions may vary depending on whether it's the flyer or the Safety Officer....

With the geofencing, it's determined electronically and the pilot will be over-ridden. However, either way it depends on the integrity of the pilot, either by observation or by setting the correct parameter. I use the Pixhawk FC and you'll need a laptop at the field to check the flight parameters that have been set.

I'd certainly not want to fly mine in manual mode much further than 200yds - orientation's awful without wings and a tail!

Pete

[John Emms 1]

Posted by Dave Hopkin on 03/08/2017 18:15:14:

Helos - 1500mm Rotor Diam and 0.60cu/10cc or 1500W Electric

Whilst I am not sure why the helicopter power limits could not be the same as the fixed wing power limits, do you not already have a size and power limit for rotor craft?

[Dave Hopkin]

Posted by Pete B - Moderator on 03/08/2017 20:41:30:

Posted by Dave Hopkin on 03/08/2017 20:04:18:

Not a bad idea but perhaps simplify it to Helos and MR restricted to 200yds from Pilot?

Manually, I suppose it's a subjective issue as to what is 200yds - opinions may vary depending on whether it's the flyer or the Safety Officer....

With the geofencing, it's determined electronically and the pilot will be over-ridden. However, either way it depends on the integrity of the pilot, either by observation or by setting the correct parameter. I use the Pixhawk FC and you'll need a laptop at the field to check the flight parameters that have been set.

I'd certainly not want to fly mine in manual mode much further than 200yds - orientation's awful without wings and a tail!

Pete

As not all MR have geo fencing we cant really make a club rule that is dependent on it - yes 200yds is subjective but at least it reminds people that they should not stray too far away

[Dave Hopkin]

Posted by John Emms 1 on 04/08/2017 22:13:43:

Posted by Dave Hopkin on 03/08/2017 18:15:14:

Helos - 1500mm Rotor Diam and 0.60cu/10cc or 1500W Electric

Whilst I am not sure why the helicopter power limits could not be the same as the fixed wing power limits, do you not already have a size and power limit for rotor craft?

Partially noise as the motor and blade noise combine + the fact that Helos tend to stay close to the ground

[Don Fry]

Mr Hopkin makes sense. A 7 kg multirotor has about 10 or 11 kg of max thrust, far more than any of the other catagories

[Frank Skilbeck]

Why don't you just class them the same as the helis, 1500mm overall dia and 1500w. In reality the guys who fly those big multirotors are doing it as an aerial video platform so flying at one location isn't their bag, they would probably only use the field for setting up. The regular club members are much more likely go for the 250 (or smaller) size, e.g. the racing type and fly these round close in. But like helis having these hovering over the strip while fixed wing fliers are in the air would need to be addressed.

[John Emms 1]

Whilst it would be quite normal, and very sensible, to have a weight limit and a limit to noise output, I do understand that the council say they need SIZE limits.

I would avoid getting too complicated in all of this. At what point does a helicopter become a multirotor? Does it become a multirotor when directional control is not from a tail rotor, or does it become a multirotor when it has more than one main rotor? What about contra-rotating rotors? Is a scale Chinook a helicopter or a multirotor?

You already have a size limit of 1,5m across the rotors of helicopters, with a 10cc or 1500W limit, so why would that not work for all rotorcraft?

And taking up (again) Frank's second point, I have flown with helicopters, both outdoor and indoor, and we both wanted to use the same bit of airspace, but the typical flight paths of flying fixed wing and helis are clearly different. Woodspring cure this issue by having separate areas for flying fixed wing and for flying ALL rotorcraft - and this has been a very successful, and safe, arrangement for many years.

I hope that is of some help.

Regards,

John