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Re: Question about oil pressure and when it bypasses
by Garrett Wysocki » 7 years ago
No I just know more vacuum = more cooling. Many high performance/larger aircraft aircraft have adjustable cowl flaps to vary cowl suction on air cooled engines. If you are experimental that would be an easy/proven way to control how much cooling you need. Research that topic.
https://www.aopa.org/news-and-media/all-news/2017/november/flight-training-magazine/how-it-works-cowl-flaps
Thank you said by: Aaron
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Re: Question about oil pressure and when it bypasses
by Aaron » 7 years ago
Anyone know if 78 psi oil pressure on takeoff with oil temp at 130, 140 ish ok?
It's good after the first takeoff
Thx
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Re: Question about oil pressure and when it bypasses
by Bill Hertzel » 7 years ago
Max Oil pressure is 73 psi and only at idle with a frozen cold engine.
So, Not OK!
What do you mean by "Good" after 1st takeoff? 40-50 psi?
Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.
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Re: Question about oil pressure and when it bypasses
by Aaron » 7 years ago
First t/o after everything was back together it was right before yellow. On my guage that's 80 psi.
Second was around 65
Third was around 55
When I noticed my oil temp hitting 230, the t/o after that was just over 40 and the next couple were the same.
The next day went up twice.
First t/o was around that 73 mark.
Second was around 60
Everything was from memory, they are close number but not perfect.
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Re: Question about oil pressure and when it bypasses
by Bill Hertzel » 6 years ago
With a special thanks to Aaron, I have the results of the End-Seal Tape Question.
I have tested three samples of Self-Fusing Silicone Tape.
Sample #1 Fuse-it Tape. 1" Wide x 0.030" Thick
Sample #2 Nashua Stretch and Seal, 1" Wide x 0.020" Thick
Sample #3 F4-Tape, 1" Wide x 0.020" Thick w/ Blue Center stripe.
Sample #4 Was a short piece of Silicon Fire Sleeve with the inner surface of the end coated with "Permatex High-Temp Red RTV Silicone Gasket Maker" used as "End-Dip" for the Fiberglass lining.
Only the F4-Tape Advertised that it was Mil-Spec A-A-59163 Type II
In looking up the actual Mil-Spec it turns out that meeting the Spec should not be exceptionally difficult.
http://everyspec.com/COMML_ITEM_DESC/A-A-59000_A-A-59999/A-A-59163_38752/
The primary requirements are that the dimensions should be reasonably accurate.
It should be able to seal to itself.
It should be able to stretch 3 times its relaxed length.
It should be "Usable" at 500°F. (Whatever that means???)
It should absorb no more than 3% in water. Not Tested.
And a few more specs about its electrical insulating properties that I did not test other than an Ohm Meter indicated that they all could insulate well beyond the 10 Million Ohm range of my Meter.
There is nothing in the Spec about resisting Fuels or Oils.
The results...
All samples were an inch wide to as accurate as you can expect to measure a piece of rubber.
The F4 tape was a very accurate 0.020" thick edge to edge.
This was the only tape with a colored center line.
This tape was advertised as a Type II Tape that is supposed to be Triangular in cross section and taper to 0.008" on one edge. The sample was constant 0.020" across, Type I.
Even though the center line is used to judge a 50% spiral overlap, its real purpose is to identify the thickness of the Type II Tape. Blue = 0.020"
The Nashua product was 0.020 thick in the middle but tapered to 0.010 at both edges.
This made for a smoother looking wrap when considering a spiral overwrap.
Good or Bad??? You decide! I like it!
The Fuse-It tape was a Heavy Duty 0.030 with only a very slight thinning at the edges.
They all self-fused to the point that only by destroying them could you get them apart.
They all stretched 3 times their length.
The Fuse it tape required pulling to the limit of my hand strength due to it being 50% thicker than the other two.
All the samples were placed in my kitchen oven at 300°F for an hour. (The Misses is used to my eccentricities.)
I figured this would be hotter than any engine compartment in normal operation.
They all survived without any noticeable change.
Next, they all went back in the Oven for another hour.
I used 525°F In case the oven's thermostat had any inaccuracy, this insured that it was at least 500°F.
At about a half hour there was a slightly noticeable chemical odor in the air.
Not enough that the Misses got upset, but enough that she made the comment that, "Something Smells".
At the end of the bake cycle, the tape had darkened somewhat, but not alarmingly.
They All still stretched to the 3X requirement.
I wrapped them around a piece of 1" Aluminum bar and they all stuck to themselves.
The next day I was able to carefully unwrap the F4 and the Fuse-It tapes. They would no longer self-seal after being baked.
The Nashua Tape partly peeled apart before it tore under the attempt. It performed the Best in this respect.
My opinion on all of this?
None of the samples technically met the Mil-Spec if you want to get picky.
Thay All met the "Intent" of the Mil-Spec in general.
Any Self-Fusing Silicon Tape you find will probably work just as well as any other for our purposes.
Nobody was willing to supply a piece of the certified $40 a foot Parker-Hannifin Tape but I suspect the main difference is that it comes with the traceability certification papers that add $39 to the otherwise $1 a foot tape.
Oh, Yeah!! The Fire-Sleeve.
It held up just fine to the Baking Cycles.
The Permatex Red RTV Gasket Material "End-Dip" still looked like new also.
All of the tapes formed a very tight seal with the Fire Sleeve.
None of the Silicon tapes actually "Fused" with the silicon of the fire Sleeve.
Experimental Aviation at it's finest!!!EndTape.jpg (You do not have access to download this file.)EndSeal.jpg (You do not have access to download this file.)
Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.
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