Marc J. Zeitlin
Paul Roberts wrote:
Here are the Cleveland brakes on my cozy (under construction). Identification tags still fresh. I measured the thickness of the rotor as 3/8 thick. Are these brakes not good enough for a cozy 4?
25 years worth of COZY mailing list archives are replete with discussions of brake issues.
While the original Cleveland brakes on the Long-EZ were acceptable, the heavy duty Clevelands are more than acceptable from an energy absorption standpoint for Long-EZ's, particularly since very few LE's pay attention to the MGW limits imposed by Burt in the POH. They're also acceptable for COZY III's at 1500 - 1600 lb. MGW.
However, with the extra weight of the COZY MKIV, even at the BOOK value of 2050 lb (which exactly zero COZY MKIV's come in at or under, including mine - most are in the 2150n - 2250 range, with a not insubstantial number even higher) even the heavy duty Clevelands that you show (and the equivalent Groves) are inadequate in emergency situations. They're OK for standard ops - they'll stop you during taxiing and in normal landings without overheating, they won't boil the fluid and they have reasonable torque values.
BUT, in an aborted takeoff at high DA's (and depending upon weight, lower DA's), you WILL exceed the energy capacity of the brakes and risk brake fade and overheating (read, strut damage). Given that you want to stop the plane before running off the end of the runway in an aborted takeoff, well, having brakes that don't fade is important.
Does this happen often? No. Has it happened? Yes. Is it a risk and something to think about? Yes. There are two MFG's of 5.00 x 5 wheels and brakes that meet the energy absorption capacity requirements of an MGW COZY MKIV at higher DA's (which lead to higher GS's at the same IAS). These are the MATCO triple puck brakes, and as of a few years ago, the new Beringer High Energy wheels/brakes.
Most COZY MKIV's do not have MATCO brakes, but a substantial percentage do (as does mine and the other MKIV in my shop now). If I had $3500 burning a hole in my pocket, I'd replace my MATCO's with Beringers as a test and to save some weight. But I don't...