Main rotor RPM

[longdog67]

Hi from a learner,
I understand about the danger of being struck by a model heli & the injuries I think it could cause.
But at what kind of rpm do the main rotors spin at? & forces involved?(blade 400 for eg) let alone some of the big gas powered helis.
Any serious injuries known about by anyone?
Second question is probably just my warped little mind at work. ;-)

[Nipster]

An average 450 class of which your Blade 400 is one, spins the main rotors at roughly 2700 rpm. Some 450 class go over 3000 rpm.
Top of my head (some one will correct me if I'm miles out) speed at the tip of the blade is over 200mph
50 class spin the blades slower circa 2000 rpm but the tip speed increases due to the larger blade travelling further so somewhere over 300 mph.

I think you'll be able to figure out the injuries involved when you look at the speeds.

Fly safely and don't forget your pre-flight checks.

[murph]

There is a video on youtube of some bloke who got hit in the leg (I think) by a blade, pretty nasty gash he had. I thhink Jason Cho's(?, 6yr old boy??) dad got hit in the eye recently at a show, though I don't think he was too badly injured. Maybe someone can shed some light on this?

[Planehazza]

I heard a story from years ago of an instructor being killed because his learner flew it too close and the rotor blades hit his throat. I don't know how much of it is true, but I don't doubt for one second that it would happen if it did hit you.

[trillian]

There was an instructor in the USA killed by a 50 heli. I don't know what happened to cause it. I know of a serious injury caused when an electric Trex 600 started unexpectedly while being worked on.

I'm sure you can find lots of injuries involving fixed-wing models as well.

Fortunately there is a general culture of safety with RC helis that prevents injuries with the exception of freak accidents or serious malfunctions.

Regarding headspeeds, 50 size helis are likely to run around 1600/1700 hovering and maybe 1900 / 2100 or so when more response is needed for 3D etc. Bigger helis tend to run a bit slower speeds.

A very rough calculation would be that for a 450 heli at 2500 rpm the tip speed is just over 200 mph and a 50 heli at 1600 rpm the tip speed is about 260 mph.

On a full scale heli, if we take a UH-1 'Huey' for example the headspeed is only 290 rpm but the rotor tip speed is over 500 mph (over 800 feet per second) and the tips can actually break the sound barrier in FF flight.

[Gate88]

The strange thing is that on Phoenix I am always crashing into my virtual self yet never came close to it in real life! I guess you're always going to duck or jump out of the way when it comes to it!

I walked into my blades once while my old Raptor was spooling down and took it right on the shin and that hurt enough, I'd hate to think how much it'd hurt if they were being powered at the time!

[fakesnake]

This is what my trex 500 did to my hand some time back, all healed up now except no longer have any feeling in my index finger.

And it was all my fault

[andylinney]

People have most certainly been killed by RC Helis / Planes in the past. The simple rule is to never underestimate the damage your model can do and so never get close enough to find out...

[Rotorhead]

Nipster you're right about 50 size speeds, I get a tip speed of 321mph on a heli running 1950rpm and a total rotor diameter of 1.4m (2x 0.6m blades plus 0.2 for the rotorhead) something it would be wise to respect and stay well clear of.....

[trillian]

Nipster you're right about 50 size speeds, I get a tip speed of 321mph on a heli running 1950rpm and a total rotor diameter of 1.4m (2x 0.6m blades plus 0.2 for the rotorhead) something it would be wise to respect and stay well clear of.....

I took the lower end of the headspeed range just as a starting point. 300 mph is over 400 feet per second. When you realise that an arrow from a hunting bow is going less than 300 feet per second you can get some idea of the energy in a blade moving that fast.

[squeaky pete]

In simple terms, its gonna f@**ing hurt!!!! So dont do it

[dam74]

Fakesnake, ouch! I'll have to watch out for this bad boy when I get one.

General rule of thumb, the bigger they are the more they hurt. Bigger, heavier blades usually do more damage. What you'll find with the larger helis have more inertia as they have a lot more weight/mass behind them.

I've gone in hot on a Blade400 when running wooden blades, plastic gears etc and I drew a bit of blood on my hand and had a bit of a sore leg but nothing serious. The jesus bolt stripped and so it spun freely so no more damage done to me. You take a larger and more robust heli with tougher drive systems and fasteners and these won't break as easy when somebody puts their hand in the way. As a result the hand will take the brunt of it and will keep taking it until something gives.

I posted up in one of the video posts of an asian guy flying a heli in a prohibited area and struck somebody in the head. Looked pretty nasty. There was also a post on Youtube in response to 600/700 being inverted near a guys head, somebody said in Brazil a child was killed when a heli struck them in the throat. At the end of the day you can be really unlucky and one wrong strike and it might hit a fragile part of the body and that is it.....game over.

[Rotorhead]

I took the lower end of the headspeed range just as a starting point. 300 mph is over 400 feet per second. When you realise that an arrow from a hunting bow is going less than 300 feet per second you can get some idea of the energy in a blade moving that fast.

Yeah, 1950 is about average for a 50 size doing 3D, glad you put it into perspective, another thing to consider is that if hit by a blade going that fast its still being powered as it slices into you.

I dont know about arrows but I'm guessing they're lighter than most blades aswell?

Faster, still powered, and heavier = steer well clear.

BMFA safety rules are there for a reason, ignore them and if anything bad happens you're not covered.

[trillian]

At the end of the day you can be really unlucky and one wrong strike and it might hit a fragile part of the body and that is it.....game over.

Well, I suppose you could always wear motocross body armour and a helmet

[dam74]

I prefer Mithril it's lighter