Aircon in RA Aircraft

[Guest nsmflyer]

This may be a stupid question, but i was thinking today, is there any reason why aircon is not in any ra aircraft, surely it wouldnt be hard to modify a car aircon system into a plane.

 

Sorry again if it's a stupid question, but it's been bugging me so had to ask.

 

 

[gavinl]

Hi

 

Just guessing that the power required and the consequent fuel use would not make it a desirable option. The time it would be needed most would usually be while doing checks or taxiing, which would also be the worse time for the engine as it would be quite a drain at idle revs. The extra weight would not be welcomed either. If a pilot is warm, most times they could always fly a little higher.

 

gav :)

 

 

[facthunter]

Aircond.

 

Forget it! It's heavy and just something to go wrong. Once you're in the air it gets 2 degrees c cooler for every 1000' of elevation. A light coloured aircraft stays cooler in the sun. (Important with composites, I'm told). Nev

 

 

[Guest brentc]

There are quite a few larger aircraft with aircon getting around. Cheiftain comes to mind and more recently the Cirrus SR20 and 22 that have it as an option. The Robinson 44 helicopter has it also as an option, however all of these aircraft are 200+ horsepower and probably can handle the load ok.

 

 

[Guest ozzie]

C210, senica, mooney, bonanza caravan are some others.

 

if you are really worried about the power loss and want real cold air try this;)

 

 

 

[Flyer]

Aircons are heavy, the penalty is a lower useful load. They're also power robbers.

 

I did all of my PPL training in Alice Springs and I can tell you from experience that you will want and need ALL the power available to you in the event of a go around etc etc ..... and then some....

 

However, in saying that, part of the checklist normally requires the aircon be turned off prior to landing and take off.

 

With all of my flying out of Alice Springs on hot days, the only time I ever got hot was taxiing around and take off (leave doors ajar helps).

 

Once established at 8500 to 9500 it was much cooler.

 

Anything below that was as rough as hell with all of the thermal activity on a 40 degree day....

 

Regards

 

Phil

 

 

[Guest ozzie]

Actually a serious answer here would be to consider upping your alternator and battery and use a 12vdc cold plate set up from a small fridge. Or try the V8 supercar setup with an esky of ice and some duct tube and fan. consider lining the cabin with thin insulation.

 

some things to also consider. an 45amp alt under full output will take around 4 to 5 hp from an engine. a rotary air con pump will draw at least 10hp plus the load on your alt from the elec clutch and fans.

 

ozzie

 

 

[youngmic]

I'm curious,

 

Many (unfortunatly not all) of the aircraft I fly have a retro fitted automotive air conditioners installed. My engineering knowledge is somewhat limited, however I would suggest you wouldn't get much change out of 20 kgs for an installation. But even worse is the shear size of the equipment which would pretty much preclude its installation.

 

I can confirm that for these retro fitted systems the check list requires off for both take off and landing, which in part is where you would like to use it. And the heat exchanger struggles at taxing speeds with out fan assist.

 

Ag machines have an optional electric driven system mounted in the aft fuselage area and again all up installation (guessing) around 20kgs.

 

However while I acknowledge that yes these systems do use some of your horsepower, my best guess would be more likely 2 or 3 tops, anyone got any hard data on this?

 

But on the upside technology keeps moving forward, Diamond (Austria) are looking at a small light weight system, and I'm sure others are to. Give it 5 to 10 years and some smart person will have a system available.

 

Ozzie, or any others, I think I can grasp the concept of the idea of an esky with ice (beer inside even better), in fact only the other week I thought of an idea exactly along the same lines (and thought it was an original idea!) as a solution for the flight crew when we operating in 40c temperatures down low.

 

Has anyone seen this type of set up or have knowledge of its usability? particularly;

 

- How long would a large size system last with say 6" scat hose ducting in and out?

 

- Could it make a difference to a somewhat drafty 20' sea container sized area?

 

- What is the general temperature drop from in to out ducting?

 

Regards

 

Mick

 

 

[Guest Flyer40]

Check this out Mick,

 

http://www.sportys.com/acb/showdetl.cfm?&did=19&product_id=10784

 

 

[youngmic]

Flyer40,

 

Brilliant!!

 

Thank you very much!

 

This may well be a starting point to a tailored design for a number of our fleet.

 

We recently had an aircraft working in 47c OAT doing back to back shifts of 5 hours plus at 200 AGL with the crew wearing flight suits and helmets with an oh so typically failed air con. A back up like this would have been great.

 

Regards

 

Mick

 

 

[Thruster87]

I'll have to modify my small esky as the idea seems pretty good. Put a thin hollow dish with many small holes on the bottom then ice on top and blow the air thru it and out at the top, nice and cool for $50.00 ? Cheers T87

 

 

[Guest brentc]

There's a mob that advertises aircon units in the aviation trader. It looks like an esky with a pipe sticking out the top. It runs off the aircraft's electrics. No idea how it works, however I'd say it was more of an evaporative cooler rather than an aircon. It just sits on a seat in your aircraft and does it's thing.

 

 

[Geoff]

Don't you go and upset your engineer Mick:angry:

 

 

[Flyer]

The core ingredient of the esky aircon is a thermoelectric cooler called a Peltier Device. You simply apply DC to the device and 1 side gets cold and the other side gets hot.

 

You see the $70 cooler eskies with no compressor...they've got one of these devices in them....

 

Rather than waffle on, I've just put a link here which will tell you all about this great device....

 

http://www.peltier-info.com/

 

Start your search here if you want to source one....type in peltier

 

http://www.oatleyelectronics.com/

 

Regards

 

Phil

 

 

[Guest Fred Bear]

There was nothing like flying the Bantam at 5,000ft or so on a summers day with shorts and t-shirt. Miss that so much.

 

 

[Ross]

There is a little line under other limitations in my Jabiru J160 owners manual that says.

 

2.7.3. Maximum air temperature for operations

 

 

 

40 degrees C for takeoff at gross weight.

 

 

 

I guess the strategy would have to be to take off early and stay high if you are expecting a hot day and descend quickly before it warms up too much.

 

I do not know what the figures are for carbon fibre aircraft.

 

Does anyone have information on it?

 

Regards

 

 

[Flyer]

There is a little line under other limitations in my Jabiru J160 owners manual that says.2.7.3. Maximum air temperature for operations

 

40 degrees C for takeoff at gross weight.

 

Regards

My thoughts would be that this relates to performance (density altitude) and not a melting fuz.

 

Who in their right mind wants to go flying on a 40 degree day....more fun at the pool with a beer ;)

 

Regards

 

Phil

 

 

[Guest brentc]

I recently took up a couple of pax in the Jab. It was right on 40 degrees. We were pretty much right on MTOW. If the elevation of the airfield had been any higher we could have been in trouble for takeoff and climbout. Luckily for most RA machines we aren't so concerned about weight and balance and MTOW because generally there is more than enough margin for error. I'd be a little concerned if for example we got our 750kg's and someone loaded up a J430 with cargo to the brim at 750kg and tried to takeoff thinking things will be normal. The 40 degree limit is a good idea for the Jab. Any more than that and things start to cook under the bonnet I've found.

 

 

[facthunter]

40 degrees.

 

You will find that this temperature is the upper limit FOR THE CHART. If you are above it there is no data available. You are not allowed to extrapolate. It's to do with DENSITY ALTITUDE, which affects Take-off distance required, climb gradient,& service ceiling etc. It's probably an arbitrary limit which could be extended to a higher temp. (would have to be formally approved by the authority), if there was a demand for it . Nev...

 

 

[Guest Fred Bear]

Just a little off-track too. Don't forget icing can occur even at these temps so don't think you are safe in summer. Just a thought...

 

 

[Yenn]

In the old days a lot of cars in Qld had a small fan on the dash to blow air over the driver. It worked and in summer I use a fan when I sit at the computer to drop the apparent temperature from sweltering to very comfortable.

 

I could just fit a 150mm dia fan in the plane, but no way would an esky fit.. The power consumption would also be much less.

 

 

[facthunter]

Principle.

 

An air conditioner is only a heat pump. You have to pump the heat from the inside and dissipate it on the outside. Requires 2 heat exchangers and at least one fan. A clever way is to cool high pressure air and then release it . As it expands adiabatically, it cools further. This can be done on the ground with external equipment. Shading the aircraft would be a good idea too. N..

 

 

[jcamp]

some things to also consider. an 45amp alt under full output will take around 4 to 5 hp from an engine.

ozzie

Boring engineering stuff:

 

45 amp x 12V= 540 Watt = 540/746 = 0.72 hp

 

not so bad for 28V at 1.69 hp but there is still some SERIOUS problems with drive/alternator/regulator/measurement there.