Calidus in hot weather

98InTheHole

Newbie
Joined
Aug 30, 2011
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Israel
OK, it sound like it is not the end of the world, especially since I would be getting the summer canopy, which has 2 large openings, so ventilation, even on the ground, should be fine. I will mostly be taking off on a small not very busy strip, so my taxi time will mostly be very short. Also (as reminded by my wife) during the hottest summer months I'm mostly not even in Israel, so this may work just fine.

Next week I'll be flying on it, can't wait, hopefully it'll meet or exceed my expectations :)

Thanks again for the help.
 

ckurz7000

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Vienna
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ArrowCopter
Hi 98,

Alex pretty much said it all. Here is my experience to complement his:

I never had a problem with being too hot once in the air. The hottest day I flew was 36 °C in full sun. But I have a sunroof and two small round, adjustable windows on the right hand side. Along with the fresh air vent in the front and the side window on the left that makes for ample ventilation to keep you cool and comfortable. And I have the fully enclosed canopy.

Any closed canopy will turn the cockpit into a baking oven when you're parked in the sun. For your latitudes and climate I would definitely recommend the summer cockpit with sunroof. As Alex pointed out: a side hinged big canopy like the one on the Calidus needs to be handled with care. Don't leave it open so that the wind can put a lot of stress on it. And don't taxi with it open because of (1) the wind and (2) possible large bumps. Both will tend to wear out the hinge attachement points.

Regarding vapor lock: I haven't experienced it yet. There is a good sized electric vent in the engine compartment, which kicks in automatically and keeps running for 4-5 minutes even after engine shut off. You can turn it on manually, too. The most important precaution is to park the gyro out of direct sun light. If there's a wind blowing, park it with the nose pointing into the wind. After engine shut down, once the vent has stopped, turn it on manually for another 4-5 minutes.

-- Chris.
 

twistair

Living in the Skies
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I forgot to mention, Chris, that vapor lock is an issue only if you make short stop when engine is stopped for up to ca. 30 minutes on a hot day before next flight. In this case engine has not enough time to lose its heat. The problem appears not when you start engine and not while taxiing - fuel pump is enough to run fuel on idle. But when you add full power then vapor lock shows itself and engine drops rpm right when your main wheels are ready to leave Globe. Nothing serious for a gyro, but in a fixed wing this drop usually appears right after lift-off when the airstrip ends.
Standard Rotax solution is to have a return hose with a .35 nozzle in it which goes from fuel line (between pump and carbs) back to tank. This nozzle is enough for vapor but too small for liquid fuel and therefore doesn't cause fuel pressure too low in flight. This is standard thing in any Rotax manual but - don't know why - isn't used in Calidus.
 
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Master Roda

The Jedi
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Feb 1, 2006
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3,227
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Scappoose.OR USA
Any closed canopy will turn the cockpit into a baking oven when you're parked in the sun.

-- Chris.

Not true. Our plastic manufacturer has provided us with 95% UV blocking windows that reduce cabin temperatures by a huge factor. Blocking this wavelength is the key apparently.

The technology is great. Our flat black instrument pod even stays cool in direct sunlight.

Jon
 

cbonnerup

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Greenville, NC / USA
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Jon,
A correction, and not trying to be a smart-ass.

FYI...UV does not cause heating - it damages skin (sunburn) and other things biological by ionization. It also plays havoc with the eyes. IR (infrared) radiation at the other end of the spectrum is what causes things to heat up from radiant energy. There are commercially available plastics with IR filtering built in - the filter rejects wavelengths from 800 nm on up. In optics it is sometimes called a 'cold window' or 'cold mirror'.

It is a good idea to use for any warmer, sunny climes; probably not so useful in Norway!

Chris
 

98InTheHole

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Aug 30, 2011
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Israel
Jon,
A correction, and not trying to be a smart-ass.

FYI...UV does not cause heating - it damages skin (sunburn) and other things biological by ionization. It also plays havoc with the eyes. IR (infrared) radiation at the other end of the spectrum is what causes things to heat up from radiant energy. There are commercially available plastics with IR filtering built in - the filter rejects wavelengths from 800 nm on up. In optics it is sometimes called a 'cold window' or 'cold mirror'.

It is a good idea to use for any warmer, sunny climes; probably not so useful in Norway!

Chris

This sounds very "scientifical", thanks!

Is there some kind of coating or something that can be done to a canopy to provide both UV and IR protection?
 

Master Roda

The Jedi
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By all means correct me. I don't pretend to know everything. That's just how it was explained to me. Whatever it is...it works :) We use it in the SCII.

Thanks for the correction.

Jon
 

Phenix5

Junior Member
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Nov 18, 2008
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Alicante, SPAIN
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Hi 98,

Just as a comment, I would like to say that in our Phenix tractor gyro you don´t have any of the described issues. Engine in front provides an extreme cool airflow right on the moment you start it up!. We also have 4 adjustable air inlets, one on each door window and two on top of the cabin. We normally use the tops ones (facing rearwards)to allow air exit the cabin compartment in flight. But on the ground you can put them looking directly onto your face and that´s a relief in hot conditions.

It is summer season here right now (Spain) and we are currently flying in an average 35 degree centigrade all the time. No problem on the ground and obviously none in flight.

We also use specially treated windshields for hot weather countries and it definetely works.

Regarding vapour lock and cooling, engine in front does that job for free. We use a Rotax 914 and it is advisable to keep the engine at idle about 5 minutes before you stop it to allow the turbo unit to cool down properly. This will make your engine live longer. So you can also use those 5 minutes to bring engine cowling temperatures down to optimal at no cost and without using any extra electrical equipment. On the other hand if you want to restart the engine on a hot day within the next 15 minutes after stopping it, prop in front will keep your engine cowling temperature within reasonable limits. It may not want to restart that nicely but you can use this trick: before stopping the engine, disconnect the fuel pump and wait until the engine starts to rattle, then stop it. Restart the engine without fuel pump and connect it on inmediately when it fires up. It will work everytime. This is not in any Rotax manual, I just discovered it by trying different ways of solving that particular problem on these engines. Anyway, vapour lock can also happen on forward mounted engines but one of the reasons will definetely be caused by unproper cowling design.

98, I know this does not help your questions but I just wanted to share with you all, one of the many advantages of a tractor configuration. Good luck on you final choice!
 

98InTheHole

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Messages
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Location
Israel
Hi 98,

Just as a comment, I would like to say that in our Phenix tractor gyro you don´t have any of the described issues. Engine in front provides an extreme cool airflow right on the moment you start it up!. We also have 4 adjustable air inlets, one on each door window and two on top of the cabin. We normally use the tops ones (facing rearwards)to allow air exit the cabin compartment in flight. But on the ground you can put them looking directly onto your face and that´s a relief in hot conditions.

It is summer season here right now (Spain) and we are currently flying in an average 35 degree centigrade all the time. No problem on the ground and obviously none in flight.

We also use specially treated windshields for hot weather countries and it definetely works.

Regarding vapour lock and cooling, engine in front does that job for free. We use a Rotax 914 and it is advisable to keep the engine at idle about 5 minutes before you stop it to allow the turbo unit to cool down properly. This will make your engine live longer. So you can also use those 5 minutes to bring engine cowling temperatures down to optimal at no cost and without using any extra electrical equipment. On the other hand if you want to restart the engine on a hot day within the next 15 minutes after stopping it, prop in front will keep your engine cowling temperature within reasonable limits. It may not want to restart that nicely but you can use this trick: before stopping the engine, disconnect the fuel pump and wait until the engine starts to rattle, then stop it. Restart the engine without fuel pump and connect it on inmediately when it fires up. It will work everytime. This is not in any Rotax manual, I just discovered it by trying different ways of solving that particular problem on these engines. Anyway, vapour lock can also happen on forward mounted engines but one of the reasons will definetely be caused by unproper cowling design.

98, I know this does not help your questions but I just wanted to share with you all, one of the many advantages of a tractor configuration. Good luck on you final choice!

Thanks for the info and the tips...
 

cbonnerup

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Yes, pre-treated Lexan for windows in an enclosed cabin is a real sweat-saver. I will use it when I get that far. Most 'UV" blocking plastics and glass exclude IR as well; but UV is in the news for most consumers.

Do not use auto window covering for glass on any polymer - it will bubble badly in the summer as the plastic outgasses.

Talk about HOT; glad I don't live in East-Central Texas at the moment!!

Chris
 

MichaelBurton

Gyro CFI
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Petaluma CA. USA
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I flew the Calidus at Mentone this summer. I left the canopy open until just prior to flight. It was not too bad. In flight it was not cool but it did not heat more than ambient temp.

I fly in the high deserts of Utah all summer long. 85F to 110f. I remove the doors of the Sparrowhawk and fly as high as I can. It is still hot but not hot enough to keep me from flying. I put one hand and foot out in flight to get some cooling.

I have found that the mornings are very cool in the desert. So I would guess it is the same for you.

Mike
 

rfsolutions

Black Sheep Rotorcraft
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Chandler, AZ
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Yes, pre-treated Lexan for windows in an enclosed cabin is a real sweat-saver. I will use it when I get that far. Most 'UV" blocking plastics and glass exclude IR as well; but UV is in the news for most consumers.

The SCII uses glass that blocks both as Chris pointed out but they advertise the UV because it is the most harmful (ionizing radiation). The heat inside the cabin is significantly reduced as demonstrated. Flying in the heat of AZ it will be welcomed.

The largest concern I would have about flying a Calidus in extreme heat would be performance. The Calidus I saw flying in high heat (100 degrees F) had dismal climb performance, somewhere in the 100-200 FPM range with 2 people and not much in the way of fuel onboard.

The Calidus may be quick in level flight and descents but climb performance is nothing to brag about.
 
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Fly Army

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Regarding vapour lock and cooling, engine in front does that job for free. We use a Rotax 914 and it is advisable to keep the engine at idle about 5 minutes before you stop it to allow the turbo unit to cool down properly. This will make your engine live longer. So you can also use those 5 minutes to bring engine cowling temperatures down to optimal at no cost and without using any extra electrical equipment. On the other hand if you want to restart the engine on a hot day within the next 15 minutes after stopping it, prop in front will keep your engine cowling temperature within reasonable limits. It may not want to restart that nicely but you can use this trick: before stopping the engine, disconnect the fuel pump and wait until the engine starts to rattle, then stop it. Restart the engine without fuel pump and connect it on inmediately when it fires up. It will work everytime. This is not in any Rotax manual, I just discovered it by trying different ways of solving that particular problem on these engines.

This technique is very similar to starting a warm fuel injected general aviation aircraft - throttle full forward, mixture full lean, as the engine fires reverse the two levers in a coordinated fashion (easier said than done in some cases). Another trick from our fixed wing brethren along with facing the aircraft into the wind when parked is to open the oil dipstick inspection door to create upward funnel or smokestack to dissipate the engine compartment heat.
 

JAL

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I fly the MTO3 sport in Australia and where I fly it gets hot and for many many months. I wouldn't worry about comfort. You can take it to the bank that if its that hot that you feel uncomfortable in the cabin that the performance of the gyro will be that you can never load it up unless you can have a very long takeoff run.

The MTOs do not perform well at high temperatures, you will need a long runway to get airborne at gross weight. This is not a criticism of the MTO3 but in gyros generally. If you have a two place lead sled you cant expect good performance at high temperatures.

Once the temperature exceeds about 35 Celsius (maybe even 32) you should consider you now own a single seat gyro. This I bet is the case for all gyros, the physics suggest that gyros are more sensitive to temperature and density altitude than all other flying machines because of the high wing loading and lots of drag.
 
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