Problems with too much power?

[SchrodingersCar]

I'm tiptoeing back into this pool and I don't have all the specifics of a build all put together yet, but as I ease back into heavy lift, ideally I'd like to build something that could handle a Movi with Red (or similar) payload, that I can use to lift much lighter (thinking of trying a Gremsy H3 with possibly a new a7r II) in the meantime while I test/save money. Is it possible to build a rig that can happily handle both without need to modify? What are the usual downsides of an overpowered bird... if there are any? Some preliminary ecalc numbers show the possibility of 40% throttle hover.

Is this a good idea, or is it generally better to build your system more closely scaled to the payload?

 

[Motopreserve]

I think ideally you would have a bird built specifically for each application, but that's not to say you can't figure out how to have 1 handle both chores. I think the key would be to find motors capable of handling various size props that would keep you in a healthy thrust range for both applications. This might take a bit of research, but I'm sure there are some contenders out there.

I also assume you could add weight while using the lighter gimbal/camera setup. Of course you wouldn't benefit from the longer flight times typically associated with lighter/more efficient rigs, but the cost savings by avoiding buying 2 MRs may help you get over that

 

[SchrodingersCar]

Yeah I'm mostly thinking of changing props to dull the power... but for curiosities sake, I can't seem to find a consistent answer: What are the downsides to flying without enough weight, or "overpowered"? Is it just harder to make smoother motions? Or is there more to it than that?

 

[Motopreserve]

Mostly it would fly twitchy and be less controllable. The 50% throttle for hover rule of thumb allows you to have enough juice in reserve if you need it for climbing out of a situation - but also gives you half the throttle stick throw to get you up to hover. If you're very overpowered, the resolution of the stick is going to be less in the low throttle range.

Especially for AP/V, this would be working against your goal of smooth flight.

 

[Bartman]

i don't disagree with what Scott is saying but it depends on the motors and all-up weight that you're looking at.

I use Tiger MT4008-18 motors for medium lift heli's where I still need to have the reserve power for larger loads. With eight of them and a decent battery load I think you'd be in the ballpark though the A7 through RED requirement is probably a bit of a stretch.

take a look at the motors with 12 and 14" props and see if they have any appeal

 

[SchrodingersCar]

I was thinking of going straight to U7s on an X8 - Trying to drop the money bomb at the beginning and put together the best system I can rather than a slow trickle of upgrades. But everything's still undecided. Kinda just wish I had the $$ for an Alta... (though I really wanna see the claimed "15 minutes in the air with a Red" with my own eyes)

Thanks for the input guys

 

[Hexacrafter]

In reply to original question:
Build a rig from a weight range from say GH4 to RED? and Use M5 and M10 on the same aircraft.
Many of our clients use the HO-1250L - U7-490 for this weight range VERY successfully.
Most use 16" T-motor Props when flying GH4 & 17" props for RED to dial the aircraft to the specific weight.
This is a Flat 8, so the X8 version is the HQ-1150L and would follow the same usage for weight ranges.
This is not a sales pitch, but rather verification that one aircraft can fill the range you are pursuing.
The reason most of our clients chose to build a range of sized & set-up aircraft is that it allows them to take the SMALLEST aircraft to the job. So a smaller HQ-850S with Avroto 3520 (X8) is a smaller aircraft for the GH4/ M5..... allowing less and smaller cases to travel with.... especially on airlines....
I hope this helps.

 

[scotth]

I'm one of the ones with the 1250L/U7-490's and VERY happy. Got it dialed very nicely with an M5/GH4 and 17" props, then turned around and stuck a Red Dragon on there without changing anything, and went straight to Bonneville on a Nike shoot. Had rotten luck with the Aeronavics quick release, dropped that for Andrew's custom isolation mount (properly designed I might add by people who know how) and haven't looked back.

 

[SchrodingersCar]

Hey Andrew, no need for the sales pitch, Sleepy and Pumpkin and Scott have all done it for you

I've actually had the HQ-850L with U7-490 on my spreadsheet for a while... or would you say that frame is too small for that potential weight?

I wish I could do the m5/m10 combo... but more likely is something like a gremsy H3 or H6 to carry our lighter cams through this summer while we save up for the M10.

 

[SleepyC]

Rent the M10 when you need it, charge customer... done.

 

[Pumpkinguy]

I can tell you that my flat hex (1100mm) with u7/490 I can easily take the weight of a stripped down red and lens with 17" props and gh4 with 16" props. No crazy hot motors or esc's at full load and very cool with gh4 and movi m5.
I think if you go with tmotor my heatsink mod is worth doing. If you need a payload bigger than 7-8kg than I'd go with the flat 8. View attachment 25781

 

[Pumpkinguy]

Rent the M10 when you need it, charge customer... done.

Exactly my thoughts. Any major city will have rentals. I know I can get the m10 or 15 for a couple hundred a day here in Toronto.

 

[Hexacrafter]

Hey Andrew, no need for the sales pitch, Sleepy and Pumpkin and Scott have all done it for you

I've actually had the HQ-850L with U7-490 on my spreadsheet for a while... or would you say that frame is too small for that potential weight?

I wish I could do the m5/m10 combo... but more likely is something like a gremsy H3 or H6 to carry our lighter cams through this summer while we save up for the M10.

I prefer the HQ1150L for RED.
The larger frame allows the larger RED camera & Larger Landing Gear to stay out of the Propeller wash.
Yes, The HQ850L will do the lift, but you may then struggle with vibrations from the wash on the Camera & Landing Gear.
Also.... I know of at least 5 clients & friends that use the M5 for RED.....
Some simple temporary modifications to the vertical camera cage tubes & it works just fine!
Hope this helps!
Andrew

 

[SchrodingersCar]

Exactly my thoughts. Any major city will have rentals. I know I can get the m10 or 15 for a couple hundred a day here in Toronto.

Not without insurance... Which leads me to my next big question... which I probably definitely should start a separate thread for.

 

[Pumpkinguy]

Not without insurance... Which leads me to my next big question... which I probably definitely should start a separate thread for.

Liability is an absolute must and is very reasonably priced. Rental and comprehensive insurance on the other hand is not cheap but cheaper that buying a new m10. Lol.

 

[scotth]

Used to be your basic inland marine equipment policy would cover you but the insurance companies have wised up and there are now drone exclusions due to the high loss rate. You can still get it, but the rate is up there. Some companies are writing standard aircraft hull policies on these things.. so you are insured for a specific aircraft and equipment. And you need a separate policy for each one. That adds up. Though not as bad as insuring a real helicopter for film work. My friend's 206 costs him over $50k/yr for the liability limits the studios demand.

 

[SleepyC]

OR... to keep insurance reasonable "The M10 fell off the 30 foot jib.. it was awful... But it happens! !

 

[scotth]

OR... to keep insurance reasonable "The M10 fell off the 30 foot jib.. it was awful... But it happens! !

In to the ocean.. and we can't find it.

 

[SchrodingersCar]

Well since you guys chimed in I guess I'll just keep things OT here... Anyone (in the US) got any links to good providers? So far the people I've reached out to (Costello, Aerialpak) provide UAV liability, but NO coverage of hull or payload? I know it's gonna cost a pretty penny, but so far I can't even seem to get a QUOTE.

 

[violetwolf]

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