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I have had two bungee cord fail on a 750 in the last few hours
Just the way that they failed made me think that it might be a possable heat issue
I know that I had not been hard on the bungee
so i put a remote temp sensor on the area of the bungee that had failed
the round radius is 7"
and the rear exit area is 1" wide by about 17.5" long
all you math wizzes can figure out the area !!
well, with that size exit I run about 234 cht and 192 on oil temps
and I took the temp on the bungee ,,,160 degress !!! all the time
and if you didnt open the oil inspection cover the ambient gets even higher just sitting there
i would think that at that temp it wouldnt take long to reallly couse problems with the rubber bands inside
well the first thing I tried today was make the radius hole on the exit 2" wider in radius
ten minute flight and the bungee temp was the same , I lowered the cht and oil 227 and 187
next I duct taped on a 2" lip right ahead of the radius , not it wasnt really solid and i think it flexed back a little in flight
but it did drop the bungee temp down to 145 degress
I did not notice a big differance on the cht and oil
so I put a SCAT tube on the bungee area with the front of the tube up by the carb holes on the upper cowling
flew it for ten minutes and never got it over 117 degress!!!
and for all the testing the ambient was 84 degress
I know there is alot of 701 running the Rotax setup that have not had any problems , but i think the 750 might need a little help on that area.
Guys should keep an eye on thier bungees .
The lower strap welded on the gear leg saved lots of headaches ,hats off to Zenith on that !!
hope this helps someone
Im thinking im going to make a cover over the bungee nose gear tube and run a SCAT tube to the top , it will direct cool air and act as a heat shield at the same time , ill get some pics posted of that soon and get some temp results
also I will make a permanet lip on the lower cowl exit