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December 10, 1997
WebChat with Brent Wellman

Deputy Project Manager, 2GCHAS,
Ames Research Center, Moffett Field, California

Thu Dec 11 11:42:24 1997

[ Susan/NASAChatHost - 0 - 09:43:12 ]
Good Morning from Ames Research Center, The chat with Brent Wellman will begin at 10 AM PST

[ Brent/Ames - 3 - 10:03:23 ]
RE: [AndersonElemSchool] This is Anderson Elementary School, Good Morning! Is it hard to fly a tiltrotor plane?
Harder than most. One must be a ble to pilot a fixed wing airplane and also a helicopter. In addition, he/she must be able to handle the changing shape of the aircraft as it "transitions" from one mode to the other.

[ Brent/Ames - 9 - 10:11:57 ]
RE: [Alex-Alex/homeschool] What's the difference between a piston engine and a jet engine for helicoptors? And what is the difference between a Comanche and a Apache helicoptor?
Two good questions. The gas turbine engine has more power for the same weight. As a result, a whole set of engineering design changes can happen. The rotor can be smaller, the tailcone smaller (don't want to chop THAT off with the main rotor!!!), more room for passengers, ca rgo (ammo, guns), etc. The introduction of the turbine to helicopters *revolutionized* helicopter design. The Apache and Comanche are two different helicopters. The first, called AH-64, is in service and was in Desert Storm. The Comanche, RAH-66 should be in service around 2003 or so.

[ Brent/Ames - 12 - 10:14:07 ]
RE: [AndersonElemSchool] What kind of a computer do you use to write helicopter design programs?
I use high-end workstations from IBM, Sun, Si licon Graphics, and HP. I access it all, though, with by trusty macintosh, where I am typing right now!

[ Brent/Ames - 13 - 10:15:41 ]
RE: [AndersonElemSchool] Have you ever ridden in a tiltrotor plane? What does it feel like?
No. I was test director for the XV-15 tiltrotor, a nd I ran things from the ground. We had two highly qualified test pilots on board.

[ Brent/Ames - 15 - 10:17:10 ]
RE: [Carl/homeschooled] Hello if you tested the Comanche did you find any problems with the origanal design
I have not tested the Comanche, but the f olks at Sikorsky's West Palm Beach, FL facility have. They are encountering the normal difficulties and are "tweaking" the design.

[ Brent/Ames - 24 - 10:21:44 ]
RE: [Alex-Alex/homeschool] What is the exact speed and flying height of the Comanche and Apache? Have you been designing any new special aircraft like the Fre nch-British Concord or the F-117A?
I don't know those off the top of my head. To find out more about the Apache, see: http://www.boeing.com/rotorcraft/military/ah64d/ah64d.htm To find out more about the Comanche, see: http://www.sikorsky.com/ <--WAY cool web site!

[ Brent/Ames - 27 - 10:23:22 ]
[AndersonElemSchool] We have Mac's at our school too! Do you use drawing software?
A little. I prefer Canvas, but I also have MacDraw PRO, and a few others. A lot of plotting packages... LOVE my mac!! ;-)

[ Brent/Ames - 30 - 10:26:51 ]
RE: [Carl/homeschooled] Did they or you use the 2gchas program to test the XV-15?
XV-15 predates those sorts of tools. It was designed and built with slide rules and t-squares... I HAVE done an XV-15 model in 2GCHAS, mostly for the practice. As far as *testing* is concerned, we tested it by actually flying it. Today, everyone wants to "flight test" in computers, but for my money, there is no substitute for actually DOING it!!

[ Brent/Ames - 32 - 10:28:58 ]
RE: [Jason] Hello Mr. Wellman, does the 2GCHAS work in conjunction with or instead of a simulator?
Good question! 2GCHAS is a comprehensive analysis program, not a simulation program. The two types serve different purposes, and there is a need for both.

[ Brent/Ames - 34 - 10:31:51 ]
RE: [Jason] I read about the structural failure of the stopped wing design, was this project ever entered in the 2GCHAS?
You will have to be a bit mo re specific, Jason. There have been several stopped rotor designs, only two of which I am at all familiar with: The X-Wing and the Canard-Rotor-Wing.

[ MSLewis-AndersonElemSchool - 35 - 10:31:56 ]
It's time for math bye for now

[ Alex-Alex/homeschool - 36 - 10:32:16 ]
Have you been doing tests on the aircraft on your computer to tell how high they can go? Have you done any tests on the SR-71?

[ Brent/Ames - 37 - 10:33:34 ]
RE: [Alex-Alex/homeschool] What is your favorite aircraft?
Usually the one I'm in! :-) For sheer spectator value, though, I like the SR-71. See: htt p://www.wvi.com/~lelandh/sr-71~1.htm

[ Alex-Alex/homeschool - 39 - 10:36:36 ]
Well, that's one of my favorite aircrafts, too! Some other ones are the XB-70 Valkyrie, the F-117A Nighthawk, and the P-51D Mustang.

[ Brent/Ames - 41 - 10:37:57 ]
RE: [AndersonElemSchool] Does the design start with a drawing or information about the motor or what?
Well, preliminary de sign is a process in itself. It can (and has) start with a sketch on a cocktail napkin. Availability of aircraft engines with their power and weight-to-power ratios, materials and materials experience, and a host of other things act to refine the design. After a prototype design is in place, computer modelling helps designers to optimize their designs. Later, CAD software aids in the parts drawings and CAM software (and robotic hardware) can help with the manufacturing process.

[ Brent/Ames - 43 - 10:42:23 ]
RE: [Jason] I have heard about some problems with the prototype of the tiltrotor design. Were you involvedin solving these problems? How did you solve them?
There were several design glitches on each of the tiltrotor designs. This last cycle, involving the V-22, was a bit more complex, because the craft is so complex (due to some requirements that do not have to do with its being a tiltrotor). Like m ost other aircraft (in 1972, the first F-14 crached in its first test series, due to mechanical failure, yet it is today a successful design).

[ Brent/Ames - 47 - 10:45:00 ]
RE: [Carl/homeschooled] I noticed you worked on RSRA do you know what helicopters had there rotors tested on it?
The RSRA only tested the Sikorsky S- 61 rotor before it was cancelled. One of them (we called them Heathcliffe and Gertrude) was fitted with the X-Wing prototype, but never flew with it before project cancellation.

[ Carl/homeschooled - 51 - 10:49:18 ]
Was it hard to become a programmer after being trained as a mechanical engineer?

[ Susan/NASAChatHost - 52 - 10:49:52 ]
Carl how do you know so much about helicopters?

For me, it means less money to work with, an end to flight testing; [ Brent/Ames - 54 - 10:51:09 ]
RE: [Carl/homeschooled] To bad RSRA looked like a good idea to be sure what a rotor would do
Yeh... :~(

[ Brent/Ames - 55 - 10:52:27 ]
RE: [Carl/homeschooled] Was it hard to become a programmer after being trained as a mechanical engineer?
Not really, you pick up basic programming sk ills as a requirement. It is needed, as well, to complete some of the homework assignments.

[ Alex-Alex/homeschool - 57 - 10:53:18 ]
I haven't had a chance to yet, but I will.

[ Brent/Ames - 58 - 10:54:12 ]
RE: [Brent/Ames] Not really, you pick up basic programming skills as a requirement. It is needed, as well, to complete some of the h omework assignments.
Also, I minored in mathematics in college.

[ Susan/NASAChatHost - 59 - 10:54:39 ]
Time to send in your last question our chat is almost over!!

[ Brent/Ames - 60 - 10:55:13 ]
RE: [Carl/homeschooled] I'v got lots of frends at Sikorsky and Pratt Whitney
Boht United Technologies Companies...Great! :-)

[ Carl/homeschooled - 62 - 10:56:58 ]
um did you ever test a notar or no tail rotor internal fan design?

[ Brent/Ames - 63 - 10:58:42 ]
Alex, I have tested actual aircraft (RSRA and XV-15) for altitude performance. You can run anything you like in computer programs, including all sorts of altitudes. I have not tested the SR-71.

[ Brent/Ames - 64 - 11:01:45 ]
RE: [Jason] Since rotors can't be tested like the conventional airfoil, how do they test the rotor's arfoil?
We run rotors in the wind tunnel. Just l ike fixed wing. A bit more dangerous, though. Rotor airfoil design is an art unto itself. Early helos used airplane airfoils, then designers came up with airfoils for the slender flexible wings that rotor blades are. Tiltrotors started using helo airfoils , but now designers have airfoils tailored especially for THEM...And the beat goes on!

[ Jason - 65 - 11:02:48 ]
Thanx Brent and Susan, have a great day!

[ Susan/NASAChatHost - 66 - 11:03:21 ]
Thanks everyone this has been a great chat, I have learned a lot thanks to great questions and Brent's wonderful answers. We hope to have a class with Brent in January with the Learning Technology Channel I will send out information on that through the updates!!

[ Brent/Ames - 67 - 11:04:08 ]
RE: [Carl/homeschooled] um did you ever test a notar or no tail rotor internal fan design?
Nope, but check out NOTAR at: http://www.boeing.com/rotorcraft/commercial/mdlite/md600n.htm

[ Carl/homeschooled - 68 - 11:05:55 ]
Thank you Brent these are some great URL's

[ Brent/Ames - 69 - 11:07:40 ]
Guess I'm done! I hope everyone had fun and learned a bit as well. Goodbye!


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