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How hot is too hot to go flying?

NinerBikes

Well Known Member
Having a huge heat spell here... my flight instruction is on hold, 100's for probably the next 7 or 8 days predicted for highs, low might be 78 to 80F at day break.


What's the limit, Celsius wise, OAT, that you'll still consider going flying in your RV-12?

Airport is at 1020 ft. Currently 38 C. at 7:00 pm, local
 
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Here in Las Vegas, 2200 feet, I have been flying a couple of other LSA 912 aircraft at 105f or 40c. The temps get into the yellow, but if you lower the nose for airspeed, and throttle back a little, you can manage it. Once above 6500 to 8000 feet, you can go full throttle again and it seems to hold temperature. Once in cruise at 8000 feet or higher, it cools back into the green. I guess the answer really depends on your particular aircraft..
 
I flew yesterday from Redlands (REI) to Perris (L65) and today (REI) to El Monte (EMT), both days around noon with temps over 100 and at gross weight. The plane had no issues climbing. It was hot inside with the vents open at the lower altitudes. Engine temps came up earlier than normal but easily managed with rpm and climb rate.
 
I flew yesterday from Redlands (REI) to Perris (L65) and today (REI) to El Monte (EMT), both days around noon with temps over 100 and at gross weight. The plane had no issues climbing. It was hot inside with the vents open at the lower altitudes. Engine temps came up earlier than normal but easily managed with rpm and climb rate.

How much water are you bringing up with you to drink during these hot spells?
 
I’m flying to lunch so there is water on the other end. Typically on long flights we take a 16oz to share, any more than that and I would have to land for a bathroom stop.
 
Here in Phoenix summers I use the heat capacity of the engine, Oil and water systems to advantage and try to get off the ground just as the oil temp goes into the green band. That way I can usually get to 3000 AGL just as the oil and CHT go into the yellow band. Then I throttle back to 4800 and let things cool off a bit before step climbing to altitude in 1000 ft increments. Seems to work well up to about 105F OAT on the ground. I should mention my 12 is an older model with the oil cooler about an inch in front of the muffler.
 
personal cooling systems?

anyone using cold water systems like they use in race cars? I guess the ice melts quickly and obvious weight penalty but for just local flights? I see the military are using cold fluid systems for helicopter pilots and even infantry. Emergency egress might be the issue if needed.
 
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- When the sweat dripping down your arm shorts out the buttons on your stick grip......... it might be too hot to fly.

- when your Koger Sun Shade catches fire....... it might be too hot to fly.

- when your mic muff melts to your lip while calling for a clearance........ it might be too hot to fly.
 
I've flown at 34C (from about sea level to about sea level). It's tolerable for the taxi out and runup, and once you're airborne and accelerating the airflow through the vents keeps it acceptable even if the vents feel like hair dryers.

But once you get down to circuit speed for the Cessnas at the arrival airport, and the propellor isn't augmenting the airflow through the vents, it gets uncomfortable *fast*. I find I have to open the tip-up as soon as i'm off the runway... I raise it enough to get the overhead latch sitting on the top of the rollbar. I do this after crossing the hold short line, but before calling ground. Then i'll get airflow into the cockpit for taxi, and it become acceptable until I shut down.
 
Slider

.... I find I have to open the tip-up as soon as i'm off the runway... I raise it enough to get the overhead latch sitting on the top of the rollbar. I do this after crossing the hold short line, but before calling ground. Then i'll get airflow into the cockpit for taxi, and it become acceptable until I shut down.

One of the reasons I am building a slider, just saying.
 
One of the reasons I am building a slider, just saying.

A slider RV-12? :D


Got in the air early today, didn't quite beat the 8 AM tower free launch, but things were already cooking at 29C.

34C when we got back with Floriduh type humidity for around here, and fire smoke from 2 TFR's burning to the north of us. Passenger cracked the canopy latch and notched it open, once I got on the brakes for taxiway "C" , mid field. It wasn't so much the heat today as it was the humidity. Motor was making easy 5250 rpms on runway, 5140 at 70 kts speed climb rate. So... Hoping that the prop pitch is close enough to being spot on right. Took off with 16 gallons of no ethanol Mogas in the tank.

Motor is running really good right now, good climb rates, but 1800 feet of climbing taking off with oil temp at 122 F saw 232F, so had to level off and back out of it after about 5 minutes at 5200 and knob to the wall. 1 1/4 inches from full throttle, level and 5050 rpm to let the oil cool down at 103 kts. I guess if your oil is getting hot, you're burning a lot of fuel and making horsepower?
 
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Departed Fredericksburg (Texas, of course) Sunday after a little visit and saw 107 OAT and ~4,500' DA about the time I broke ground. Was wondering why it felt like a high altitude takeoff. I've got an iron stomach, but with the heat and bumps all the way up to 10,000', I'd do it different next time. And probably good to be aware of the performance issues with the heat. Even when flying in lower Texas.
 
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Passenger cracked the canopy latch and notched it open, once I got on the brakes for taxiway "C" , mid field. Took off with 16 gallons of no ethanol Mogas in the tank.

Congratulations on your check ride, did it go as expected?

Where in So Cal are you finding "no ethanol Mogas"?
 
Congratulations on your check ride, did it go as expected?

Where in So Cal are you finding "no ethanol Mogas"?

Not a check ride. We take turns, sometimes his RV-12, sometimes my RV-12, to go get breakfast at KSZP at Airport 126 Cafe.

I find it at one Costco near KWHP. Since late March/ April when there was a surplus of cheap gas, cheaper than making alcohol out of corn.
 
I did a 3-day formation aerobatics course earlier this year on 44 degC days.

Many litres of water. Quite a few Hydralyte supplements too (miracle stuff in hot weather, if your local drug store doesn't carry it, find one that does - https://hydralyte.com.au/)

Overnight inversions are fun during heatwaves: 6:45am departure @ 36 degC on the ground, 38 degC at 2000' AGL.

Not overly comfortable. Under normal circumstances I'd decide it was a bad day to go flying at about 36 degC, and I feel bad about introducing newbies to aviation with passenger flights if it's more than 34 degC.

- mark
 
I've flown at 34C (from about sea level to about sea level). It's tolerable for the taxi out and runup, and once you're airborne and accelerating the airflow through the vents keeps it acceptable even if the vents feel like hair dryers.

But once you get down to circuit speed for the Cessnas at the arrival airport, and the propellor isn't augmenting the airflow through the vents, it gets uncomfortable *fast*. I find I have to open the tip-up as soon as i'm off the runway... I raise it enough to get the overhead latch sitting on the top of the rollbar. I do this after crossing the hold short line, but before calling ground. Then i'll get airflow into the cockpit for taxi, and it become acceptable until I shut down.

Good advice.

Lessons on hold again... night flight and landings on Monday got shut down when the cloud cover started rolling in after 5 touch and go's at KCMA. Instructor also got me some experience flying by instruments only at night, when clouds started rolling in from the Pacific Ocean. Trust those instruments!

Currently, severe problems with inversion temps... couldn't get much beyond 5000 ft with oil temps not cooperating, even at 300 fpm climb rate at 4900 rpm, throttle backed off. Wed and Thurs lessons scratched, 32C by 9 AM, I know oil temps on climb outs to get to 3500 AGL will not cooperate to do more power on and power off stalls for practice.

Waiting for October to cool off a bit and show some fall temperatures. Won't be the least bit surprised if Ethanol now shows up in my Mogas, due to winter blend gasoline showing up at the refineries here in Southern CA
 
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How hot is it getting?

If "it" is air temps, usually 33 to 36 C by 11 AM on Thursday, Santa Ana wind conditions.


Monday night, out of CMA with 5000 rpm 85 to 90 KT at 350 fpm climb rate, 10 gals left, about 50# under gross ... I had to call it quits at 5100 ASL, oil temp was holding 245 to 247, then saw 248 F and went into the red. The inversion was still there, probably 6000 to 7000 ft up. We needed 5500 to 6500 to fly the coastal route over KLAX VOR then exit south side. That and visibility was becoming a problem, fog was rolling in off the ocean, onto the coast, ground was showing it was no longer visible on his Fore Flight software on his iPad. So lesson got diverted, starting losing elevation and back to WHP for my first night landing. Really didn't seem that different than landing during the day time, although the wind was dead calm on approach, rock steady, very easy.

It got up to 106F today in the San Fernando Valley where I live. Over 78 at 7 am. Strange for October.
 
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I fly in similar conditions, maybe worse and get much better performance with lower oil temp. I just removed the cooling plenum, I’ll see if that makes a difference.
 
I fly in similar conditions, maybe worse and get much better performance with lower oil temp. I just removed the cooling plenum, I’ll see if that makes a difference.

If I knew what I was doing with fiberglass work, I'd cut the lower cowling plenum, reglass it and move the oil cooler another inch farther forward. It would fix the heat problem in the summer, but then run much colder in the winter. I am running the full synthetic Mobil 1 oil, so I'm pretty sure nothing inside the motor and gearbox is really breaking the oil down at those temperatures, it's well within the safety range of a Racing motor oil for air cooled motorcycle motors capable of 11 to 13,000 rpm redlines, as long as the viscosity stays in range at those temps.

It's been extremely hot weather with inversions above the past 2 months. If I wasn't a student having to take lessons when the instructor is available, I would probably pass on going flying in the heat. But right now, I don't really have that option, if I want to finish getting a pilot's license, as all the CFI's seem to be still quite busy right now, at least around here.

Once I am able to solo, about 210# will be gone out of the right seat when I am not flying dual, so that should help quite a bit. Soon, I hope... soon.
 
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I fly fire aircraft so we fly all day every day so we have to go period. But I am instructing still in the evening hours here and there. Ya its hot but my private student is getting lots of night time practice and nothing says as a private you can't do a bulk of the stuff at night so that's what we are doing. There's a few things that needs to be done middle of the day and we save that for my days off and sweat it out.

Did you get a different instructor after the last issue you had?
 
Niner,
You buy the gas and give us a bedroom, we'll fly our -12 out and mod your plenum for you. <smile>
 
I fly fire aircraft so we fly all day every day so we have to go period. But I am instructing still in the evening hours here and there. Ya its hot but my private student is getting lots of night time practice and nothing says as a private you can't do a bulk of the stuff at night so that's what we are doing. There's a few things that needs to be done middle of the day and we save that for my days off and sweat it out.

Did you get a different instructor after the last issue you had?
Yes, new instructor, and quite satisfied with his method of teaching. Been taking 1.5 to 2 hours of lessons dual instruction flying, and getting much more learning/ practice in per session. This instructor is a good match for me. Very direct and demonstrative.

This heat can't keep up forever, it's October, so sooner or later the temp inversion is going to let go and get back to normal.
 
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Yes, new instructor, and quite satisfied with his method of teaching. Been taking 1.5 to 2 hours of lessons dual instruction flying, and getting much more learning/ practice in per session. This instructor is a good match for me. Very direct and demonstrative.

This heat can't keep up forever, it's October, so sooner or later the temp inversion is going to let go and get back to normal.

Good to hear! If you ever make it out to F70 let me know. I would like to see a 12 up close.

I hope the heat keeps up till November so I get some OT :D
 
SeaGull is close by, to you I think.... not sure where he's going for lunch these days, or if he does evening flights. He has a very, very well equipped -12, maybe catch up with him?
 
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Good to hear! If you ever make it out to F70 let me know. I would like to see a 12 up close.

I hope the heat keeps up till November so I get some OT :D

I was there (French Valley) with my -12 today from 9:00 - 1:00, my wife is getting instruction. Her next lesson is Wednesday at 11:00.
 
Tgibbs,

Hi there. I’m at F70 also. I no longer have a -12 since Walt (seagull) bought it. I now have a -9A I keep there, along with my partner Gary. Perhaps we can all get together Wednesday when Seagull comes down.

Alex
 
I won't be around Wednesday, hopefully picking up my RV4 and bringing it home Wednesday night or Thursday. Send me a message, I am usually around every evening working on stuff at the hangar from sunset ish until I'm tired. Have a hangar in the blue and white section
 
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