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Scale Model RC Helicopters > Scale auto's
 
 
mbrewer
Heliman
Location: Corpus Christi, TX

My Posts This: Topic  Forum		How well would a scale bird with a 3-4 blade main rotor auto rotate compared to two blades and flybar?

"I'd give ya my 2 cents, but I just spent it on my heli"
11-02-2009 03:55 PM
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Christopher J
Key Veteran
Location: Kansas City, MO Californian lost in land of Oz

My Posts This: Topic  Forum		If set up correctly a multi blade head auto's pretty well. Granted it's a "one shot" deal as you may not have as much in reserve inertia as you would on a heavybladed two blade head, but doable all the same.

Christopher J
East Coast Vario Field Rep
"Still all set & Flying the original"
11-02-2009 10:34 PM
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crawfish
Heliman
Location: bridge city ,texas,usa

My Posts This: Topic  Forum		autos great

i have a 4 bladed head on my 407 and it autos great it has sooooo much in reserve at the bottom. i sugest you auto it a lot in the pod and boom before you do it in a fuse.
11-02-2009 10:41 PM
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Copter Doctor
Elite Veteran
Location: daleville/ft.rucker, al- home of army aviation

My Posts This: Topic  Forum		all true but also keepin mind, the heavier the model, the less reserve you will have for cusioning. that super scaler with all the details of the fullsize will probably heavier than you would like for autos so if you are building one you wish to do autos with on a regular basis,i suggest not building one that will be heavy.

drive a rotary, fly a rotorcraft
11-03-2009 12:05 AM
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Wayne Parrish
Senior Heliman
Location: Apex,NC,USA

My Posts This: Topic  Forum		I have a Vario BELL 47 G III and at 30 lbs it autos beautifully ! I actually looks so much like the full scale .
11-03-2009 12:07 AM
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Dr.Tim
Key Veteran
Location: Mojave Desert

My Posts This: Topic  Forum		My Puma Auto's like a Meteorite ... If you nail it you can do it but, You have to nail it and you had better be in forward flight!

From Simple minds come simple ideas! Starwood Models, Approach Engineering .
11-03-2009 03:43 AM
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SeismicCWave
Veteran
Location: Hilo, Hawaii

My Posts This: Topic  Forum		>>How well would a scale bird with a 3-4 blade main rotor auto rotate compared to two blades and flybar?<<

As well as your nerve will hold up.

The ability to auto is not so much a function of how many blades and flybar. It has to do with inertia stored in your blades and the disk loading of your helicopter. Then there is also the air temperature, air density, your altitude, forward speed etc.

Let's just say you wouldn't want to practice auto with a scale helicopter that you spent hundred of hours in building. Unless you have to do it for some other reasons.
11-03-2009 04:00 AM
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Copter Doctor
Elite Veteran
Location: daleville/ft.rucker, al- home of army aviation

My Posts This: Topic  Forum
Quote 
Let's just say you wouldn't want to practice auto with a scale helicopter that you spent hundred of hours in building. Unless you have to do it for some other reasons.
AAAAAAAAAMEN!!!!
i usually have a scaler that i confidently auto all the time. it is usually a sort scale ship that isnt very detailed. right now its a 50 size jetranger. i have in the past used a 30 size longranger and twinstar. the right blades will auto well provided the disc loading is low like seismic pointed out.
Dr Tim, your puma is the same as my blackhawk. the only way that thing sees an auto is if the engine actually quits and you cant get the mattress out under it in time

drive a rotary, fly a rotorcraft
11-03-2009 04:42 AM
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mbrewer
Heliman
Location: Corpus Christi, TX

My Posts This: Topic  Forum		Thanks guys. Whats the formula for figuring disk loading? What is a good number to shoot for?

"I'd give ya my 2 cents, but I just spent it on my heli"
11-03-2009 05:20 AM
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SeismicCWave
Veteran
Location: Hilo, Hawaii

My Posts This: Topic  Forum		>>Whats the formula for figuring disk loading? What is a good number to shoot for?<<

Total disk area divide by weight. There is no hard and fast number. Just try and compare that to a helicopter that you know can auto rotate well.
Something like the current crop of 90 size 3D machines. Take the total rotor span multiply by pi then divided by the flying weight should give you a good number.
11-03-2009 06:55 AM
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heliwreckr
Heliman
Location: Battle Creek, Taxigan

My Posts This: Topic  Forum		another thing to factor would be total blade mass

paul

It's not crashed 'til it hits the ground
11-03-2009 01:08 PM
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OTCP64
Heliman
Location: Balto Md

My Posts This: Topic  Forum		Scale auto's

DR>TIM
Your Puma sounds very scale.I have a pilots manual from the 70's
for the Bell Jet Ranger that says you need to be at 70 knots FF
to auto.It also said"engine off the bell jet ranger has the glide
ratio of a tapered brick"always thought bell had quite a sense of
humor back then.

Chopper Bob
11-03-2009 03:25 PM
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WIRLYBIRD
Senior Heliman
Location: CAPE TOWN / SOUTH AFRICA.

My Posts This: Topic  Forum		I'm often told that if you spiral your helli down in an auto , you will dramatically increase the head speed , as compared to a straight line into wind. Needless to say I'm not that brave , and so far have been lucky with My 30 pound NH90 turbine , but most all of the landings have been less than light. Of course if I put wider cord blades , etc , it would in the end just be another set of compromises. So , I think the trick is for each pilot to not only set his up for just flight , but also take into account the autos , that can be the the saving grace when the engine quits.
Dave.

WHAT GOES UP MUST SURELY COME DOWN.
11-03-2009 03:28 PM
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Wayne Parrish
Senior Heliman
Location: Apex,NC,USA

My Posts This: Topic  Forum		You may not "want" to auto your bird,BUT,there will more than likely come a time when you sure wish you had practiced it !! If my Bell goes up for a flight it rarely ends a flight without a full auto at some time during that time.I think auto's are one of the most fun maneauvers you can do with a helicopter.
11-04-2009 01:58 AM
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seattle_helo
Key Veteran
Location: Seattle, WA USA

My Posts This: Topic  Forum		I had to auto my big Vario 500 with five blades earlier this summer after an engine flame out. I was terrified but it ended up being okay in the end. I was amazed at how much energy is stored in those blades.
11-04-2009 07:18 AM
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Wayne Parrish
Senior Heliman
Location: Apex,NC,USA

My Posts This: Topic  Forum		I practiced some downwind autos yesterday ,about 6-8 mph ,and they were almost identical to proper into the wind autos. I had never tried them with the big bell but it handled it very well,after all,if you have an engine out or tail rotor out it will happen when its the worst conditions.Its not going to wait untill you get back around for a into the wind auto ! Wayne
11-05-2009 01:29 PM
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Copter Doctor
Elite Veteran
Location: daleville/ft.rucker, al- home of army aviation

My Posts This: Topic  Forum		not a multibladed head on this machine but it was built with the ability to practice autos in mind. this was shot a few years ago in atlanta Ga.
http://www.youtube.com/watch?v=7V2y9msJa24

drive a rotary, fly a rotorcraft
11-05-2009 08:53 PM
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Christopher J
Key Veteran
Location: Kansas City, MO Californian lost in land of Oz

My Posts This: Topic  Forum
Quote 
You may not "want" to auto your bird,BUT,there will more than likely come a time when you sure wish you had practiced it !!
I couldn't agree with this more!! Some years back I was flying my Airwolf, after competing in the scale event, with CopterDoctor. Was having a nice "unwind/destress" flight when the main tranny let go in the middle of a turn. I leveled the heli (miracle), chased the piro with the cyclic and after a short and strained interchange of words with Emile I auto'ed it. Due to no forward flight it was a rough one but did well. Flared to soon and got a bit of a bounce. Damage only amounted to the wood floor plate seperating from the fuse.

Dang sure glad I practiced autos with a heavy bird, saved my ship from total destruction.

Christopher J
East Coast Vario Field Rep
"Still all set & Flying the original"
11-06-2009 02:15 AM
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Copter Doctor
Elite Veteran
Location: daleville/ft.rucker, al- home of army aviation

My Posts This: Topic  Forum		i remember that chris, you did a great save.

drive a rotary, fly a rotorcraft
11-06-2009 02:40 AM
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Daniel Reese
Senior Heliman
Location: Urbana OH

My Posts This: Topic  Forum		AUTOS -
It's true that turning during the descent will increase rotor rpm but it also DRAMATICALLY increases the speed of the descent! You'd better be on your game when you try that!

In flying the real thing, the straight-in autos are pretty simple: Motor quits (intentionally or not), lower the collective (Pitch), forward cyclic to get some airspeed (60mph in a full-size EnstromF28, varies by helicopter type), flare at about 30' until it stops moving forward or starts to descend, then level out and pull collective (pitch) to cushion the landing.
A turning auto goes pretty much the same but once you start the turn, you've got to pull pitch and/or aft cyclic to keep the airspeed where you want it and not let the rotor rpm get to high.

In an RC heli- all the same aerodynamic effects are in play- if you get the right forward speed in the descent phase and flare at the right moment, you can make it work. Turning on the way down will give you a lot more to think about on the way in.
11-06-2009 12:41 PM
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Scale Model RC Helicopters > Scale auto's
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