RunRyder RC
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 1781 views Post Reply
Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › Effect of temperature on heli performance
07-18-2006 05:53 PM  14 years ago
Topic Vote0Post 1
Yug

rrMaster

UK. Herts

MyPosts All Forum Topic
Effect of temperature on heli performance
'ere in the UK, it's between 30 and 40 deg C and it's normally between 10 to 20. Yesterday evening, I was rather supprised at how little power my heli had, and was nearly caught out a couple of times when doing low stuff
some figures..........
30 degC 810mb density of air = 0.92 kg/m^3
6 degC 1005mb density of air = 1.31 kg/m^3

Now considering this is a two fold problem at elevated temperatures/pressures where firstly the engine charge is less so less power, and secondly the blades have less air to work with so less lift. It really nackered my timing and general responses.

BRING BACK WINTER
Vegetable rights and Peace
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
07-18-2006 06:37 PM  14 years ago
Andy from Sandy

rrElite Veteran

UK

MyPosts All Forum Topic
Yep, all internal combustion engines love a damp atmosphere, not just our heli engines.

I even noticed early afternoon driving to the field that the car was down on power in 33 degC.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
07-18-2006 06:57 PM  14 years ago
RayJayJohnsonJr

rrKey Veteran

Midwest

MyPosts All Forum Topic
all internal combustion engines love a damp atmosphere
Huh?


-Mark

.
There, their and they're. It's really that simple.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
07-18-2006 07:11 PM  14 years ago
ADRYAN

rrKey Veteran

Stouffville, Ontario, Canada

MyPosts All Forum Topic
I've been having the same problem these past few days...30-40 degrees celsius temperature... hot engine, no power. I leaned it out to squeeze some power out, I had to auto it in coz it overheated. I ended up trying to catch a good tuning instead of flying... at least I watched other guys fly amazingly.


A

.
DYNAX/OS91 : 9303/S649pcm : GY601/9251 : CSMRL10/9253 : 7.4vLipo/Regulator : KO2123s(ai/el/pi)
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-18-2006 07:26 PM  14 years ago
fixxxer

rrApprentice

Stoke-on-Trent

MyPosts All Forum Topic
As it getters hotter you should really be richening it not leaning it out, just askin for trouble that way
SHARE  PM  EMAIL  Attn:RR  Quote
07-18-2006 07:30 PM  14 years ago
heliboy1023

rrVeteran

Tinton Falls, NJ

MyPosts All Forum Topic
As it getters hotter you should really be richening it not leaning it out, just askin for trouble that way
Actually, you are wrong here. The hotter it gets, the LESS oxygen in the air, this means you really do have to lean it out to get it to run well.

That is why I don't run my rc cars that much in the summer. To get the power out of them, you need to lean it out, but on very hot days, it just heats up to much since there isn't enough cold air to keep cooling the motor.
You know you have to many heli's only when your wallet is empty.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
07-18-2006 07:50 PM  14 years ago
helidog

rrApprentice

usa

MyPosts All Forum Topic
Markerbeacon

(Quote)
Huh?


Mark I have to agree with that answer.?????

I’m not going to get deep into this one and explain internal combustion engine 101
But I will give you a little hint.

On a cold day engines run great because the air (oxygen) molecules are squeezed together thus having to richen a bit. The more oxygen the more fuel is needed. So NOT to run in a lean condition.
Don’t try to ask for major power on a hot humid day you will not get it because air (oxygen) molecules are farther apart and the engine begins to bog because it is to rich. The only way to fight off the effects of temp and humidity is to run a blower or ram air system on the engine to compress the oxygen molecules together for a better air fuel mixture needed for the clean powerful combustion we all look for. This is why jet turbine engines run so well in any condition because they compress the air (oxygen)and more or less create there own atmospheric environment. Turbines run better in cool air even with a little moisture there is no problem with power you have to remember water contains oxygen also.

The effect on turbine .vs I.C.E this is a discussion all its own.
Its nice to be the Big Dog.
SHARE  PM  EMAIL  Attn:RR  Quote
07-18-2006 07:52 PM  14 years ago
robhurlin

rrKey Veteran

Pretoria, South Africa

MyPosts All Forum Topic
Welcome to our world - 4600' altitude (860mb pressure @ 15 degC) , typical winter day temperature 18 to 25 degC, summer day temperature 25 to 35 degC and we don't fly with 30% Nitro 'cause it's too expensive!

On a hot summer's day we definitely loose a lot of performance. We lean out a click or three for the lower air density and fly carefully!
Rob.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
07-18-2006 07:56 PM  14 years ago
ADRYAN

rrKey Veteran

Stouffville, Ontario, Canada

MyPosts All Forum Topic
Yup... you run lean on a hot humid day... the danger is overheating the motor, so you try to compensate with just having enough to lubricate and cool down the engine.


A


.
DYNAX/OS91 : 9303/S649pcm : GY601/9251 : CSMRL10/9253 : 7.4vLipo/Regulator : KO2123s(ai/el/pi)
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-18-2006 08:37 PM  14 years ago
helidog

rrApprentice

usa

MyPosts All Forum Topic
And I thought we lived in a perfect world.

Its always a fight isnt it????????????
Its nice to be the Big Dog.
SHARE  PM  EMAIL  Attn:RR  Quote
07-18-2006 10:39 PM  14 years ago
RayJayJohnsonJr

rrKey Veteran

Midwest

MyPosts All Forum Topic
The only way to fight off the effects of temp and humidity is to run a blower or ram air system on the engine to compress the oxygen molecules together for a better air fuel mixture needed for the clean powerful combustion we all look for. This is why jet turbine engines run so well in any condition because they compress the air....
A turbine engine is a normally aspirated engine, just like a non- supercharged (turbo or engine driven) reciprocating engine.

-Mark
There, their and they're. It's really that simple.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
07-18-2006 10:46 PM  14 years ago
Yug

rrMaster

UK. Herts

MyPosts All Forum Topic
As I pointed out in my 1st post, the engine mixture is only half the problem. The fact that the blades have less air to manhandle makes a drastic difference; just like with sailing boats.Vegetable rights and Peace
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
07-18-2006 10:53 PM  14 years ago
barndoorski

rrNovice

Woodstock IL. USA

MyPosts All Forum Topic
A turbine engine is a normally aspirated engine, just like a non- supercharged (turbo or engine driven) reciprocating engine.

-Mark
What?? Nothing like each other.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
07-18-2006 10:55 PM  14 years ago
Chris Lupa

rrKey Veteran

Lancaster, UK

MyPosts All Forum Topic
Went out this evening. The heli had a lot less lift and the engine power was down.Sponsored by CSM and QuickUK
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-18-2006 10:57 PM  14 years ago
tchavei

rrProfessor

Portugal

MyPosts All Forum Topic
I agree with Guy Yug Martin

It rained today which brought the temps down from 39C to 29C and my Freya seems a totally diferent machine! I had ALOT more power and finally understood the meaning of a "90 sized machine". Note that I posted a few days ago that my Freya seemed to be slower than my Evo 50... well guess what... the last time I flew the evo was more than a month ago and temps were alot lower! I guess I found the explanation.


Tony

--------------------
"Perfection and patience usually walk side by side..."
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-18-2006 11:01 PM  14 years ago
RayJayJohnsonJr

rrKey Veteran

Midwest

MyPosts All Forum Topic
barndoorski,

They are the same in that they are both normally aspirated. helidog was trying to make a comparison to a turbo charged recip. A turbine engine is NOT turbocharged.

-Mark
There, their and they're. It's really that simple.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
07-18-2006 11:05 PM  14 years ago
Yug

rrMaster

UK. Herts

MyPosts All Forum Topic
Hmmm, I'm just wondering what the overall effect of reduced air density has, in respect of: with lower density, the blades have less air to work with, so the engine doesn't have to work as hard to maintain a given HS. Dunno how linear this kind of relationship would be, and what the mathematical relationship between the air density V thrust given constant parameters like HS and AOA. Perhaps with the effects of lower air density, the effects of reduced engine power balance out with the power required to maintain the HS, so at the end of the day, the primary issue is simply thrust and cyclic response. Certainly yesterday, I was struggling with timing on rolling circles and tictocs. Haven't been out today but I believe tomorrow will be even hottet, so tomorrow evening should be interesting.Vegetable rights and Peace
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
07-18-2006 11:15 PM  14 years ago
helidog

rrApprentice

usa

MyPosts All Forum Topic
I see you are missing my point.
A turbine engine compresses the air entering the engine this in-turn compresses the air (oxygen) molecules. A piston engine will have a greater problem with temperature change and humidity than these engines unless you are running a blower or ram air or turbine to compress the incoming air. That is my point.
Its nice to be the Big Dog.
SHARE  PM  EMAIL  Attn:RR  Quote
07-18-2006 11:22 PM  14 years ago
cwhover

rrApprentice

El Paso, TX

MyPosts All Forum Topic
5000' and 98 F (about 37 C) here, and I can tell you in my experience the density altitude power drop more than cancels out the reduced drag. When I go to the Phoenix funflies (about 3000' I think) My helis seem like unboggable beasts. Autos are also quite a different experience here.Carl
VISA field rep
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
07-18-2006 11:28 PM  14 years ago
barndoorski

rrNovice

Woodstock IL. USA

MyPosts All Forum Topic
They are the same in that they are both normally aspirated. helidog was trying to make a comparison to a turbo charged recip. A turbine engine is NOT turbocharged.

-Mark
This is why JET TURBINE engines run so well in any condition because they compress the air
You are right it is not "turbocharged" but a jet turbine uses the same principles as a turbocharger. There is a turbine wheel or wheels that are driven by the combustion of the jet. These in turn, turn the compressor wheel or wheels. Usually they have a verying pitch from the first wheel to the last to increase the pressure of the incoming air. Without these "compressor" wheels a turbine would not work. By your definition everything is normally aspirated because at some point even in a turbo or blown engine the air comes in "normally"
I am with helidog on this one
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 1781 views Post Reply
Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › Effect of temperature on heli performance
Print TOPIC

 6  Topic Subscribe

Friday, June 18 - 3:12 pm - Copyright © 2000-2021 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online