What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Brake fire... should I file insurance?

Imbeccad

I'm New Here
Hi guys-
Recently had a brake fire, from a recent brake lock up after landing and during taxi, on my 6A...

This resulted in the tire, wheel pant and fairing, brake lines at the wheel and possibly the brake assembly burning up fairly good. We are waiting to hear from a mechanic, but anticipating that the cost to fix might be between 3-4K. Trying to figure out the best route, pay out of pocket or file an insurance claim (no deductible). I?m new to all this, so if anyone has any thoughts I?d love the feedback and to hear if anyone has been in this same boat.

Secondary- does anyone have any experience with a brake fire- any salvageable parts? We probably had close to a minute of fire exposure.

Thanks again!

Becca
 
Wow hard to imagine it could cost that much. A new wheel, brake, tire, flex line for brake line, and the fiberglass parts.

Find a home-builder (I mean an airplane builder, not a house builder ;) in your area that is willing to help. You'll be flying again in a couple of weekends.
 
Sorry no advice on the direction to go, I would talk with my insurance agent about the potential issues there. but that is me. You have arrived at the right forum for making some good builder contacts in your area!!

As an owner, you should get the digital parts and construction manual from Vans. You (or mechanic) can get prices from Vans, and they are the best available. Only an owner can buy many of the parts, you certainly qualify.

Also, you may (likely) have older wheel pants, so do some research on the new pressure recovery style. It is a good opportunity for upgrade. Faster too, significantly.

The dragging of the brakes due to sticking pedals is not uncommon, and might be the root cause. There are some off-plan improvements for the condition. An RV expert could look and tell you.

As an owner, you also have access to Vans technical assistance call line.

Keep us posted!
 
Last edited:
Insurance

If you have a no deductable policy and the cost is going to be several thousand dollars, file a claim! Otherwise why have insurance?
If you are worrying about the premiums going up because you filed, then find another company. After your laim. Just my opinion.
 
this just happened to a friend

Conditioning his kit-standard brakes prior to airworthiness inspection. Said he was doing extended 30-40mph taxi with brakes applied. Wheel pants on. At end of second run the length of the taxiway he saw smoke rolling out both sides. RV-10, Conventional non-Royco brake fluid, standard nitrile O-rings. Extinguished the flaming side with a fire extinguisher. The other side was smoldering, both tires ruined. Both brake rotors said to be deeply scored - no idea how. He's understandably pretty bummed to come this close to first flight and almost lose the plane. I'd give him my Matco's and wheel pants off my one-year-to-go build and get back in line for more parts if I could.

This raises several questions/ issues. What is the recommended procedure for breaking in the brake linings?

Should there be a ground crewman with radio present for this procedure to watch for smoke?

Should the pants ever be on while this is done? His take about 2 hours to remove/reinstall for reasons unclear to me - mine come off and on in a jiffy. This inconvenience clearly played a role in his decision not to go pant-less for brake conditioning runs.

Do we need more airflow in the pants, especially if not upgrading to bigger brakes, more temp-tolerant fluids and parts? This seems to be a relatively rare event, but such a potential tragedy. A brake fire could cost one of us an airplane, or leave us stranded in the bush. Having happened to a fellow builder who has been such an encouragement to me, it hits really close to home.

Sad day.


 
One of the first questions they ask on an insurance application is "Have you had any claims within the past ___ years?"
Recent claims DO have an effect on your premiums, whether keeping your current underwriter or switching companies. There was a recent post from a gentlemen who was selling his -8 after several claims within a short period of time causing his premiums to skyrocket to 12K. Bite the bullet and fix it out of pocket, it may very well be cheaper in the long run. Save the insurance for when you really need it, (hopefully never).
 
Last edited:
SPjUuaAl.jpg
[/url]

Bill,

Here?s a Cleveland brake doc...about page 11 or 12 they go over a new lining break in procedure.

https://www.parker.com/parkerimages...& Brake Division/Kit Documents/199-65 Kit.pdf


I do it pants off...wheel, that is~ :D One taxi run, shutdown, jump out and check for anything amiss. If good, repeat...

Hope that helps.

Rob
 
I think part of your decision also depends on how comfortable you are doing things yourself. I can't see the cost of fixing this to be more then 500$ if you do it yourself.

Personally I just can't see myself giving somebody that much money to do it for me.... . You can see it as an opportunity to get into the building part of experimental airplanes without actually having to build a whole airplane.

Oliver
 
Thanks to everyone for the feedback! I really appreciate it.

I would have the boyfriend, (Wingnut) fix the plane, but unfortunately he?s working out of town for quite a stretch, and so I?m having to go the A&P route, which will be a lot pricier.

If you notice a dragging or stuck brake, what is the best protocol in that situation?

Thanks again for the feedback!
 
This raises several questions/ issues. What is the recommended procedure for breaking in the brake linings?

I recommend not doing it.

Seriously, I quit the break-in procedure and couldn't tell any difference. They will settle in with normal usage. If the first few flights are off a runway so short that the last few percent of pad performance is critical, it's the wrong runway.
 
I recommend not doing it.

Seriously, I quit the break-in procedure and couldn't tell any difference. They will settle in with normal usage. If the first few flights are off a runway so short that the last few percent of pad performance is critical, it's the wrong runway.
I came to the same conclusion. I just land a little hot and apply medium hard braking to "condition them" the first time out. Seems to be about the same as a low-speed 1700' taxi at 1700rpm. I did something to my last pads as they would no longer hold at run-up, so I replaced them and did the above procedure and everything is back to where it should be.
 
Brake fire

We have fixed this very thing at my shop. Count your blessings that you didn?t run into something and have a prop strike. I would fix it my self or have others fix what I didn?t have the knowledge, skill, and ability to do and would not file an insurance claim. I have an assortment of used wheels, brakes, calipers, and tires which I would sell reasonable. I also have a new complete never installed left wheel pant kit if that is the side you damaged. Going with the diy approach it won?t be that bad. Line up some buddies, with experience, to help with the pant installation
Happy to help call if you wish to discuss further,
Terry
 
I recommend not doing it.

Seriously, I quit the break-in procedure and couldn't tell any difference. They will settle in with normal usage. If the first few flights are off a runway so short that the last few percent of pad performance is critical, it's the wrong runway.

I?m With Dan - I stopped doing brake break-in decades ago, and usually get several years out of my brake pads on all of my taildraggers.

Just my experince.
 
I'll make a note of Dan and Paul's opinion - and scratch that off my 1st-flight readiness card. Brake fire is an experience I don't need.
 
ask the insurer?

just another data point; I had a non-aviation claim, and the insurer would not let me buy a used gadget, even if under the replacement max. value!
They absolutely insisted on an invoice from a business for a new gadget.
It turned out ok for me, but eliminated the option to 'fix it myself'.

check with the insurer, that might just answer a few questions. :)
 
Don't

I would say "don't file a claim". I ran into this with my glider. My first claim was small. I asked the insurance company if I should file or not. They said, of course, that is what we are here for.

This happened twice more. Same question, same answer. So 3 claims over about 6-7 years.

One year, I didn't get renewed. They said the underwriter wouldn't renew me because of multiple claims. I said, "but I asked each time, and you said to file". I ended up getting a call-back from the owner apologizing for what occurred, but he could not change the underwriter's mind.

So I tried to get new insurance. They ask: Have you ever had previous claims? Note, they don't ask "in the last x years". So I have to answer yes. Then they ask: Have you ever been dropped by a previous insurance company? Again I have to answer yes.

So, the long and short of it for me, is avoid the claim unless you can't afford the repair.
 
I recommend not doing it.

Seriously, I quit the break-in procedure and couldn't tell any difference. They will settle in with normal usage. If the first few flights are off a runway so short that the last few percent of pad performance is critical, it's the wrong runway.

I came to the same conclusion. I just land a little hot and apply medium hard braking to "condition them" the first time out. Seems to be about the same as a low-speed 1700' taxi at 1700rpm. I did something to my last pads as they would no longer hold at run-up, so I replaced them and did the above procedure and everything is back to where it should be.

I have been doing the same thing for over 20-years. The RV is too light of an aircraft to use the recommended taxi procedure.
 
Hi guys-
Recently had a brake fire, from a recent brake lock up after landing and during taxi, on my 6A...

This resulted in the tire, wheel pant and fairing, brake lines at the wheel and possibly the brake assembly burning up fairly good. We are waiting to hear from a mechanic, but anticipating that the cost to fix might be between 3-4K. Trying to figure out the best route, pay out of pocket or file an insurance claim (no deductible). I?m new to all this, so if anyone has any thoughts I?d love the feedback and to hear if anyone has been in this same boat.

Secondary- does anyone have any experience with a brake fire- any salvageable parts? We probably had close to a minute of fire exposure.

Thanks again!

Becca

I saw the after fire results of an RV-8 brake fire. The wheel and brake caliper were still good and reusable. The Wheel, brake, and caliper are the expensive parts. IF the wheel and caliper are good, I would NOT file an insurance claim.

The insurance company is in business to make money. You will pay for the repair either by the actual cost or in higher insurance premiums.
 
:) I think he gets a pass on that work travel.

Where are you located? I bet some fellow RV'er/VAF member is willing to help you out.
 
Don't let clean disks and new pads make you think you need to force conditioning's heat into your pads.

I think the first few taxiing applications feeling firm but ineffective makes folks think they need to add conditioning heat, as others have said. If you do, no pants and allow cooling under observation back at an extinguisher or hose.

The new pads mate quickly to the disks with normal taxi use. Good for runup holding? Go fly. Avoid brake to vacate early on first 3 landings and don't plan on having max brakes for rejects for first three takeoffs.
 
The drag the breaks method often ends up badly.
I advise folks to just fly it and do firm stops for the first few landings, letting the brakes cool completely before repeating.
After a couple of applications they'll be fine.
 
I have a geeky engineer friend who documented the brake disc temperatures on his Lancair 360 using an IR sensor and a data acquisition system. He published a bunch of color graphs (which I won't post here due to copyright), but the bottom line is that his brake disc temperatures peaked out at about 800F on landing, then decayed to roughly 400-500F over the next 30 seconds when taxiing back to the hangar. This was with NO wheel pants. He also noted that "Cool down was very slow without air movement.' Something to think about for you guys and gals with wheel pants. Maybe you need cowl flaps on your wheel pants? LOL!

My friend's data comports with my own redneck experiment five years ago. With a new Matco steel disc, I observed the "temper colors" on the disc after landing. The colors indicated about 700F after a hard landing.
 
To answer the OP's question in post #10, I'm not sure how similar the RV-r brake pedals are to the RV-7, but it is likely you need to do the "long bolt" mod that puts the brake pedals on a common axis, then also the "spring mod" which is described below to stop binding if you have any. Unfortunately the pictures have evaporated because the hosting site I was using has disappeared, but I'll dig some more up and repost them. I've run this mod now for about 200 landings and they work great and feel they way brakes should. I am with the other guys regarding run-in of new pads being unnecessary. So long as your disks are clean and you've made sure they adequately stop the aircraft, it is really a non issue.:


"After a recent post in another thread from someone asking about brake return spring mods, I thought I should finally update this thread with my brake modifications. I assembled my Matco master pistons with the springs recommended in this thread and there was only a barely perceptible increase in return force. I subsequently took some measurements of the spring force in the matco's, ran a few calcs, and came up with an alternative spring solution that will double the current spring force. The original spring upgrade was a maximum of 6lb in compression. This one is 30lb. I've tested them out over the past week during my taxi tests and they feel perfect, with no risk of dragging brake, even if your toes are naturally leaning on the pedals, but not too much force that they become an incomberance when you want the brakes. I also modified the collar sleeve arrangement so that even at full brake compression, there is no way that the spring can rub on the ram. The sliding collar is also a self lubricating polymer, which should help with longevity. Just make sure when you assemble things that the collar is low enough to just clear the top mounting tab, but not so low that you restrict compression of the ram. My aircraft is an RV-7, and I would absolutely recommend the long-bolt (single axis) mod to the brake pedal to eliminate binding, in addition to the spring upgrade. You'll also see in the photos some another mod I did to make some standoffs. These are just aluminum split collars and a piece of tubing cut into thirds, then riveted in place with some long AN470AD4 rivets (the collars are countersunk on the inside and I back riveted it against an appropriate diameter bolt shank). I've also stacked two more short pieces of the cut tubing in between to give myself a little further distance.
Anyway the McMaster Carr parts list is as follows.
Spring 9657K435
Lower nylon sleeve bearing: 6294K441
washers (for seating the lower nylon sleeve bearing) 90295A470
Top nylon sleeve bearing: 6389K625
Set screw shaft collar: 9946K13

For the standoffs:
Two piece collar: 6436K136
Aluminum tubing: 9056K79"

Hope this helps.
Tom.
RV-7

free image hosting sites

upload image online and share link
 
Last edited:
Conditioning his kit-standard brakes prior to airworthiness inspection. Said he was doing extended 30-40mph taxi with brakes applied. Wheel pants on. At end of second run the length of the taxiway he saw smoke rolling out both sides. RV-10, Conventional non-Royco brake fluid, standard nitrile O-rings. Extinguished the flaming side with a fire extinguisher. The other side was smoldering, both tires ruined. Both brake rotors said to be deeply scored - no idea how. He's understandably pretty bummed to come this close to first flight and almost lose the plane. I'd give him my Matco's and wheel pants off my one-year-to-go build and get back in line for more parts if I could.

This raises several questions/ issues. What is the recommended procedure for breaking in the brake linings?

Should there be a ground crewman with radio present for this procedure to watch for smoke?

Should the pants ever be on while this is done? His take about 2 hours to remove/reinstall for reasons unclear to me - mine come off and on in a jiffy. This inconvenience clearly played a role in his decision not to go pant-less for brake conditioning runs.

Do we need more airflow in the pants, especially if not upgrading to bigger brakes, more temp-tolerant fluids and parts? This seems to be a relatively rare event, but such a potential tragedy. A brake fire could cost one of us an airplane, or leave us stranded in the bush. Having happened to a fellow builder who has been such an encouragement to me, it hits really close to home.

Sad day.



Hey Bill- I’m really sorry to hear about your friends plane as well. Really frustrating. Any chance that you could put me in touch with your friend.... just curious how he went about deeming what was still salvageable and safe for flight.

I’m not sure how to add photos here, but my wheel pant is looking pretty similar to your buddy’s.

Thanks for the help!
 
Last edited:
I?ve never bought into the whole ?conditioning? scheme, and have never done it. I don?t know what problem is supposedly being solved by doing it. I?ve not seen brake pads falling apart or not holding.

Side note: One cannot expect remotely comparable braking performance between our planes and cars. The mass being slowed per wheel is similar to smaller cars, yet the pads and rotors are probably only 10-20% or so as massive. Rapid braking turns a lot of kinetic energy into rotor heating, with very little convected away in those few seconds. The temperature data from the earlier post should be eye opening.

Side note 2: It is good practice to remove the paint from the rotors prior to use.
 
a mighty big thank you

Tom,
Thanks for posting the parts list. I went ahead and ordered 6 sets for my RV9A (Pure + attrition).
What a wonderful post, you took all the work out of this mod, thank you very much for taking the time to document the parts needed.
 
I recommend not doing it.

Seriously, I quit the break-in procedure and couldn't tell any difference. They will settle in with normal usage. If the first few flights are off a runway so short that the last few percent of pad performance is critical, it's the wrong runway.

I concur. I've owned and maintained my own airplanes for 31 years now and never done more than one good stop from a moderately high taxi speed and done. Taxiing up and down the runway at close to flying speed is just nuts.
 
Forget the insurance company. Not worth having a claim on your record for this repair.
Take detailed pictures and talk to the wheel/brake manufacturer to see what's salvageable. Hopefully you can find someone local from here to help out.
Next time around use The Royco 782 brake fluid, it has a higher flash point (Spruce sells it), and also change your caliper orings to the more heat resistant ones made out of Viton (McMaster Carr sells them). Your brakes don't have to necessarily lock up to catch on fire. Dragging them long enough will do.
I kept burning up pads on my Matco brakes so I instrumented my brake calipers with thermocouples. I can see my brake temps on my Efis. It appears that the worst thing to do is hold onto the brakes when they are hot. They pick up heat quickly when they are in contact with the disc. Better to just tap them and let go immediately.

Lenny
 
Yes, type-K ring thermocouples under one of the 4 caliper bolts.
The AFS Efis has two additional thermocouple inputs for turbo inlet temperatures that show up on the screen when you select a turbo engine in the settings.
 
brake caliper temps

So what kind of temperatures are you seeing?

I'm seeing 130-150F during normal landings with careful use of the brakes.

After a fairly long taxi at OSH last week I saw 240F caliper temps just before shutdown. The original nitrile o-rings are good to 250F. Viton is good into the 400s.
 
...Viton is good into the 400s.
Those caliper temps don't seem too bad. I have the original Matco brakes. I'll have to look into what O-rings came with them. Edit: Matco supplies the Buna N (Nitrile) O-rings. I found this, though, on another site (emphasis mine):
Viton is far superior to Buna for high temperature applications. Viton seals provide an indefinite seal for temperatures up to 400?F, and for temperatures up to 600?F they offer an excellent seal for more than 48 hours. Buna on the other hand is only effective up to 250?F. However, Buna seals provide a low temperature sealing option with effective sealing down to temperatures of ?22?F, while temperatures below 5?F render Viton seals ineffective as they become quite hard and inflexible.
I guess everything in airplane design is a tradeoff, but I certainly wouldn't want to be in a Challenger type situation with the cold O-rings. Of course, with your setup, you can monitor the O-ring temps before landing.
 
Agree with Dan

I recommend not doing it.

Seriously, I quit the break-in procedure and couldn't tell any difference. They will settle in with normal usage. If the first few flights are off a runway so short that the last few percent of pad performance is critical, it's the wrong runway.

I just rode the brakes a bit going to the hold short and took off on my first flight. No pants and air flow cool them down. Landing and taxi back will more than likely show good brakes.

I just did this as I replaces my rotors and pads, static run up prior to takeoff and the brakes held fine.

I think just normal taxi out is all that is needed.
 
brake fluid and o-rings

The brake temperature charts mentioned above by Snopercod are at the end of the following report. It was taxi out, once around the pattern, a moderately aggressive stop, then taxi, park and cool down.

http://n91cz.net/Brake_Caliper/Improved%20Braking%20Performance.pdf

What exactly caught fire in the original incident? Did a brake line fail?
Previous fires have been blamed on the low temperature rating of the o-rings, and subsequent leaking of low flash point brake fluid.

This is why I upgraded all my brakes to support DOT 5.1 fluid, which has a very high flash point. The negatives are upgrading all the o-rings, fluid needs to be changed more frequently, and the fluid is not too nice to paint.

Several threads on this: https://vansairforce.net/community/showthread.php?t=16685
 
Last edited:
Previous fires have been blamed on the low temperature rating of the o-rings, and subsequent leaking of low flash point brake fluid.

This is why I upgraded all my brakes to support DOT 5.1 fluid, which has a very high flash point. The negatives are upgrading all the o-rings, fluid needs to be changed more frequently, and the fluid is not too nice to paint.

Several threads on this: https://vansairforce.net/community/showthread.php?t=16685

Do you have Matco MC's? If so, where did you find a viton stat-o-seal?

Larry
 
Previous fires have been blamed on the low temperature rating of the o-rings, and subsequent leaking of low flash point brake fluid.

In the Lancair world, I don't know of any brake fires. All the stock caliper O-rings are be Buna-N.
My only personal brake fire exposure was friend with a fixed gear Glasair. His brake caught fire after a heavy rejected takeoff on a short runway. Melted the brake line. It had wheel pants.

Despite disc temperatures of 800 deg F, my caliper body only reaches 150 deg F ten minutes after shut down. I measured the caliper because of the 250 deg F limit on Buna-N. Can't reach that with a retractable.
 
EPDM stat-o-seal NAS1523-3P

Do you have Matco MC's? If so, where did you find a viton stat-o-seal?

Larry

Mike C sent me a set EPDM of stat-o-seals. Not sure if has more. He noted that the part number of an EPDM stat-o-seal is NAS1523-3P.

https://vansairforce.net/community/showpost.php?p=491383&postcount=36

Something from Pegasus about different rubbers. When they say braking system they are assuming a "auto" braking system that uses non-petroleum brake fluid like glycol ether/borate ester, like I use, DOT 5.1.
PegasusAutoRacing said:
EPDM

While NBR and FKM have similar chemical resistance, EPDM is completely different. It is incompatible with petroleum (oil and gasoline), but it is compatible with alcohols (ethanol, methanol, and nitromethane), water, coolants (both ethylene and propylene glycol), and glycol-based brake fluid. Of all three rubber types, EPDM is the only one that should be considered for use anywhere in a braking system. (Of course there have to be exceptions -- the Citroen and Rolls-Royce high-pressure brake/suspension systems that use green hydraulic oil must avoid EPDM and should use FKM instead.)

https://www.pegasusautoracing.com/document.asp?DocID=TECH00147
 
Last edited:
brake fires - rare

In the Lancair world, I don't know of any brake fires. ...
I think brake fires on RVs are also very rare, but I decided if I can greatly reduce that risk for a few dollars of o-rings and a couple of hours of work, why not? My only concern, which I have addressed with labeling and in my POH, is that a future owner puts in mineral brake fluid, or that I struggle finding replacement o-rings down the road. I guess we can't have it all, can we? :)
 
This is why I upgraded all my brakes to support DOT 5.1 fluid, which has a very high flash point. The negatives are upgrading all the o-rings, fluid needs to be changed more frequently, and the fluid is not too nice to paint.

What is the recommendation for frequency of changing brake fluid for both types, the fire resistant Mil-H-83282 and the stuff used in general aviation Mil-H-5606?
 
Last edited:
change frequency

What is the recommendation for frequency of changing brake fluid for both types, Mil-H-83282 and the stuff used in general aviation Mil-H-5606?
For the DOT 5.1 and other glycol ether/borate ester I've read recommendations to change it yearly, but I think it depends mainly on likelihood of water contamination. If your system is well-sealed, you can probably go longer. Not sure on the mineral oil-based fluid. My original plan was to change it yearly during the regular inspection, since it takes about 30 mins and costs about 10 dollars, but I've recently learned here on VAF that I can buy a tester that indicates the amount of water in the fluid, so I might try that to see if I can go every 2 years or more on a change.
 
What is the recommendation for frequency of changing brake fluid for both types, the fire resistant Mil-H-83282 and the stuff used in general aviation Mil-H-5606?

GLycol based auto fluids need regular changing, due to their ability to absorb and retain water from the atmosphere and therefore create corrosion problems. Mineral oil based fluids, as used in aviation, will not absorb or carry moisture. About the only place moisture can get in is through the canister and any water that gets in will just float on top of the fluid until it evaporates. This different than oil in your engine where moisture content is very high and you have high speed spinning parts that can emulsify the moisture into the oil.

As you know, that oil is several million years old, so it doesn't break down due to time and you can't really wear it out in a brake system that is sealed and generally protected from contaminants and heat.

You can get debris in the fluid at the MC and calipar from rubber break down and alum fretting. However, this is pretty minor and can be dealt with via fluid changes when those parts are overhauled due to seal failure.

Larry
 
Last edited:
GLycol based auto fluids need regular changing, due to their ability to absorb and retain water from the atmosphere and therefore create corrosion problems. Mineral oil based fluids, as used in aviation, will not absorb or carry moisture. About the only place moisture can get in is through the canister and any water that gets in will just float on top of the fluid until it evaporates. This different than oil in your engine where moisture content is very high and you have high speed spinning parts that can emulsify the moisture into the oil.

As you know, that oil is several million years old, so it doesn't break down due to time and you can't really wear it out in a brake system that is sealed and generally protected from contaminants and heat.

You can get debris in the fluid at the MC and calipar from rubber break down and alum fretting. However, this is pretty minor and can be dealt with via fluid changes when those parts are overhauled due to seal failure.

Larry
Larry, I have been watching the news, and i know that we now live in an upside down Bizzaro world but I did not know that oil is more dense than water now. :D

Merry Christmas
 
Larry, I have been watching the news, and i know that we now live in an upside down Bizzaro world but I did not know that oil is more dense than water now. :D

Merry Christmas

Yes, I am definitely blaming my lapse in sanity on Covid.:D I learned that trick from the airlines, where EVERY delay was Wx related. I officially stand corrected and appreciate you keeping me honest. Again, I typed faster than my brain could keep up with.
 
Last edited:
theoretical number for rotor temperature

I ran some numbers for the kinetic energy of an aircraft transferred to heat at the rotor web. this does not account for pad heating or any other heating, nor for cooling of the rotor for braking elapsed time. it is simply the total aircraft energy turned into heating the rotor web. what was interesting is the effect rotor web thickness has on the temperature.

hypothetical numbers:
brake outer rotor dia = 6 inches
brake inner rotor dia = 3 inches
steel specific heat (constant) = .125 BTU/lb-F
aircraft landing speed = 60 kts
aircraft weight = 1700 lbs


rotor web thickness:
.275 inch, total delta theoretical max temperature = 1580 F
.225 inch, total delta theoretical max temperature = 1935 F

the theoretical delta temperature for these two thicknesses = 355 F

or another way, every .001 inch rotor thickness reduction = +7 degrees in max delta rotor temperature

conclusion: the thinner the web the higher the rotor temperature, duh

hey, take it easy on the brakes!
 
Last edited:
I ran some numbers for the kinetic energy of an aircraft transferred to heat at the rotor web. ...

hey, take it easy on the brakes!
DanH ran some numbers a while back as well, and the takeaway for me was that you get one full speed full braking stop. After that stop, you better have lunch and let the brakes cool cuz if you try it again, you're in dangerous territory.
 
Back
Top