BeechTalk - BT - Jets with normal cruise of 0.7 mach or better?

Username Protected · **Posted:** 21 Oct 2022, 17:32

Username Protected wrote:

How thick is the body filler? Anything over 1/4" will crack over time. You could try some flexible body filler when you redo it, maybe that will keep it from cracking.

It probably varies in thickness from 0.050 to 0.150 inches. it does have cracks because it is on aluminum that experiences great temperature swings (-60 C to 55 C is possible) and the CTE of the aluminum and the Bondo don't match.

I am looking for better material for the redo. There are body fillers with fiberglass, and with metal fillers, so trying to analyze what I can use and what would work best. For example:

Fiberglass filler:
https://www.3m.com/3M/en_US/p/d/b40067470/

Metal filler:
https://www.3m.com/3M/en_US/p/d/b40067480/

My hope is to do this job once and forever so it lasts.

The tricky part is that the spec is to keep a fairly precise gap between the deflated seal and the frame surface, but you can only measure that with the door closed when you can't work the material. The MM is no help since it provides no guidance on technique, just "make it so". Hmm.

My current thinking is that you build it up somewhat more than you need and do a lot of sanding. It sounds labor intensive and messy.

I bet there is some person at some shop who has done this and really knows how, I just got to find them.

Mike C.

Username Protected · **Posted:** 21 Oct 2022, 22:49

Username Protected wrote:

... we could do that, but then the thread drift would lead us to tire ply count, or cabin window sunshades, or maybe rudder trim authority.

And the answer would STILL be Mu2 haha

Username Protected · **Posted:** 22 Oct 2022, 16:02

you really don't use brakes on the MU2, just pull the props evenly to flight idle when you have the nose wheel on, that creates quite a bit of drag. You have reverse if you need it, but that almost never happens on a runway over 3500' I have landed on snowy runways on a few occasions, non-event although significant crosswinds could make that more sporting.

Jeff Axel
N228WP

Username Protected · **Posted:** 23 Oct 2022, 00:49

Username Protected wrote:

you really don't use brakes on the MU2

I had my MU2 1600 hours and 13 years.

Never changed brake pads. You really never use brakes. They might last longer than an engine TBO.

My Citation V has brake stacks that are 3 and 10 years old. Wear indicator still shows them in the early part of their life. So it isn't hard on brakes, either, due to having TRs.

Mike C.

Username Protected · **Posted:** 23 Oct 2022, 09:41

Minor niggle. About 200 ias…[/quote]

Not sure what is meant here. The relative wind on the broken elements of the windshield was 300kts.

Username Protected · **Posted:** 23 Oct 2022, 23:11

mighta come up, Cessna 551 Citation II/SP depressurization fatal, 4 onboard

Citation Crash Baltic Sea 4 Sept 2022
https://www.google.com/search?q=Citatio ... channel=fs

Username Protected · **Posted:** 24 Oct 2022, 01:17

Username Protected wrote:

mighta come up, Cessna 551 Citation II/SP depressurization fatal, 4 onboard

Citation Crash Baltic Sea 4 Sept 2022
https://www.google.com/search?q=Citatio ... channel=fs

Yes, here: viewtopic.php?f=41&t=211482

Username Protected · **Posted:** 24 Oct 2022, 08:35

Username Protected wrote:

Minor niggle. About 200 ias…

Not sure what is meant here. The relative wind on the broken elements of the windshield was 300kts.[/quote]

Correct. The relative wind was 300kts.

However, the noise and blustery turbulent conditions you experienced in the cockpit (the “real feel” if you will) was 200 kts.

Username Protected · **Posted:** 25 Oct 2022, 09:29

Username Protected wrote:

The old L1011's were fast. We flew them around at .86. The computer would store a couple old flight plans, so you could page through them and see what other crews had been doing. One day a Chief Pilot was out flying and he paged through the computer and saw a flight plan in there at .90. So he called the old Captain in and said "hey why were you going .90?" The reply from the grumpy old Captain was "Because the POS wouldn't go any faster." I've always loved that story! Sorry for the thread creep.

So that “grumpy old captain” was what… 59 1/2 years old? Guess they aged more in the olden days.

Username Protected · **Posted:** 25 Oct 2022, 09:45

Username Protected wrote:

Minor niggle. About 200 ias…

Not sure what is meant here. The relative wind on the broken elements of the windshield was 300kts.

Username Protected · **Posted:** 25 Oct 2022, 09:59

Israel, it looks like you fly a Cirrus. If it is a Turbo Cirrus you will note in your POH that the Vno and Vne of your Cirrus decreases as you climb above 18,000 feet.

Username Protected · **Posted:** 25 Oct 2022, 10:26

Username Protected wrote:

The Lear 35's with the Garrett 731 fan engines had a lot of reserve bleed air, and as I recall could maintain a 14,000 foot cabin altitude up in the 40's with a cabin window blown out, directing all the bleed air to the cabin.

There's no chance that is correct.

A hole the size of a window with 6 PSI drop across it (14,000 ft to FL400) would require abut 25,000 SCFM of air, or about one ton of air per minute. Just no way the engine can deliver that much air, maybe not even out the tailpipe.

Mike C.

Username Protected · **Posted:** 25 Oct 2022, 10:36

I think pilots forget (or aren’t taught) that IAS isn’t really an airspeed, it’s a dynamic pressure meter. The units are practical, but carry little meaning above sea level. TAS is an actual airspeed.

Username Protected · **Posted:** 25 Oct 2022, 10:39

Username Protected wrote:

For my V, 120 knots on the nose means 300 knots groundspeed. That is tolerable. [Emphasis mine]

Ooof. Everything is relative. Getting my daily dose of humility early today.

Username Protected · **Posted:** 25 Oct 2022, 11:02

Username Protected wrote:

Correct. The relative wind was 300kts.

However, the noise and blustery turbulent conditions you experienced in the cockpit (the “real feel” if you will) was 200 kts.

Down low the effects of wind between IAS and TAS are similar. They higher you are the more those diverge. And in the flight levels the effects of wind start acting according to Mach speed as opposed to indicated. For instance if you were high enough and going 200 KIAS, the heat from the wind would burn your flesh and rip it off. Think about the SR71 traveling with a subsonic indicated airspeed has a leading edge temperature of 600-900 degrees Fahrenheit. So at high altitude mach speed is more relevant to things like temperature, expansion rate of parachutes, and flutter. We simplify KIAS and TAS for understanding which works with low flying aircraft, but falls apart with faster aircraft traveling at higher altitudes. Short answer 300 KTAS at 200 indicated on your face feels a lot different than 200 KTAS on on your face at sea level, at 200 indicated.