Reno Stead Report 8/30

[toldjaso]

Re: Reno Stead Report 8/30

If Toldjaso sez it is so then it is fact.

Well, I am not always right.
I thought I was wrong once, but as it turns out, I was mistaken about that.

[RichH]

Re: Reno Stead Report 8/30

The motocrosser (forget his name- Mark Hanna was it?- in a P-51?)

That was Bob "Hurricane" Hannah, and yep... he ate the floorboard after losing the horizontal trim tab on Voodoo when it was painted white.

Mark Hanna was the dude who flew 109's...

[flyingjibus]

Re: Reno Stead Report 8/30

Please use the term "Motocross Legend" because that's what he was.

[toldjaso]

Re: Reno Stead Report 8/30

Is that a myth or has that/can that be measured?

Mostly Magic.

Ponder this: true, a prop is an airfoil, just like the wing. A wing produces lift to counteract the weight of the aircraft, causing it to rise up and fly.
A propeller acts like a screw, just like a boat prop. Screwing it's way through the fluid (air) on a plane, or water (on a boat). Coarser pitch for more bite, up to a point.

We used to spray WD-40 on Bell 407 rotor blades to get them to smooth out when tracking them (less friction). However, I could not tell you if it made it fly any better or worse in the air.

Most tricks with props are minute, and hard to measure for the average Joe.

[V1670]

Re: Reno Stead Report 8/30

Let me be another to say THANKS, DAWG for your reports

[knot4u]

Re: Reno Stead Report 8/30

Flutter is an aerodynamic issue that I've never heard attributed to a propeller. GG and MAII did not have flutter issues. The bearcat was more difficult to control with the 3-blade on the course.

[toldjaso]

Re: Reno Stead Report 8/30

Flutter is an aerodynamic issue that I've never heard attributed to a propeller. GG and MAII did not have flutter issues. The bearcat was more difficult to control with the 3-blade on the course.

The NTSB seems to think otherwise. Read the reports for GG and MAII. Both attributed to flutter. (Make sure to read the bottom of the second page of each report).

The biggest concern with the three blade was possible control surface excitation caused by harmonic vibrations in the airframe, caused by the prop "beating up" the airframe.

The rudder fluttered and ripped off the Polen Special. The new owner had been warned that there was an RPM range to avoid, due to prop harmonics. He did not avoid it, lost rudder in flight.

A test pilot can "excite" the controls by smacking the control stick with a rubber mallet. Just ask Skip Holm about the time he did that to Tsunami on a test flight, and then landed minus both elevators and some of the horizontal stabilizer.

[ChrisMX105]

Re: Reno Stead Report 8/30

The 140+ page NTSB report is well worth the read, and the reason I get pissed every time someone tries to make the crash out to be something other than willful ignorance. (Galloping Ghost that is)

[toldjaso]

Re: Reno Stead Report 8/30

The 140+ page NTSB report is well worth the read, and the reason I get pissed every time someone tries to make the crash out to be something other than willful ignorance. (Galloping Ghost that is)

We can't change the past, but we need to learn from it and remember not to do the same kind of mistakes over again.

You usually get the same kind of results that the last guy did, if you let that happen.

So, how many flights on the extremely Rare Bear so far this week?

[ChrisMX105]

Re: Reno Stead Report 8/30

Why I push people to read the full NTSB report, few ever do.

[Curt_B]

Re: Reno Stead Report 8/30

IIRC,, Friday maybe Saturday last year they were sanding the paint off of the prop.. If this is the same prop I guess it proved to them that it worked better without the paint they had on it during qualifying last year? Not sure why it works better though

I noticed that too last year. Prop paint adds to the thickness of the airfoil, which is bad for transonics where a shock sits on the, 'upper', surface at the tip. Assumed they figured this out, and wanted to minimize the thickness of the paint. A polished surface provides laminar flow up to the shock, and for a typical airfoil, shock location will be further aft. The airflow across this polished prop is called free transition since the boundary layer is allowed to transition from laminar to turbulent on it's own. The sanded state is called fixed transition. In those rare geometric airfoil cases where the flow between fixed and free transition is the same, the sanded condition is the best, since the shock won't cause a laminar flow separation. For most airfoils, the shock is further back on the polished surface, and the amount of flow separation behind the shock is reduced.

Now this is the cool part! Since the paint on such a short chord significantly changes the airfoil thickness, paint can be used to change the chordwise thickness distribution, meaning.... paint can be used to change the airfoil shape, and increase thrust at higher speed by increasing drag divergence. Hope this isn't too confusing, I'll clarify if there is any interest.

[Race 29]

Re: Reno Stead Report 8/30

I seem to remember a documentary a few years back about 3M developing a film called "Riblett Film" that had microscopic peaks and valleys on the surface. When applied to a fuselage or wing, made the surface rough and decreased aerodynamic static drag. Much like the surface of shark skin. It was developed for the airline industry (less drag = less fuel), and the studies showed it did it's job very well. I don't know if it's still in use. I've often wondered how come air racers don't use it. Maybe weight?

http://news.3m.com/press-release/company/3m-reveals-successful-collaboration-bmw-oracle-racing-33rd-americas-cup-match

http://m-selig.ae.illinois.edu/pubs/SareenDetersHenrySelig-2011-AIAA-2011-558-WindTurbineAirfoilsRiblets.pdf

https://www.mecheng.osu.edu/nlbb/files/nlbb/Thesis%20-%20Dean.pdf

http://www.vsail.info/2010/04/02/video-bmw-oracles-3m-riblet-film/

Race 29

[marada mx3]

Re: Reno Stead Report 8/30

Why I push people to read the full NTSB report, few ever do.

Hopefully this doesn't veer too far off topic.......
I'm the same way with the Challenger and Columbia Accident Reports. When I hear people say the Orbiters "exploded", I tell them they should read the reports so they can understand why the Orbiters broke apart. They're only about 400 pages each.
Tommy

[Desertdawg]

Re: Reno Stead Report 8/30

So, how many flights on the extremely Rare Bear so far this week?

2 x Monday
1 x Tuesday

[badman]

Re: Reno Stead Report 8/30

Anyone know what the results of these 3 flights were? Is the Team happy so far? Are they chasing problem(s)? Has the lost HP been found?