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Old Sep 22, 2001, 12:14 PM
Flying Welder Pilot
Plane Crazy's Avatar
Reno, Nevada
Joined Jan 2001
1,137 Posts
Yf-23 Black Widow Twin Midi

Yeah, I have been pretty bored waiting for parts on the F18. I was at the LHS last week and they had a plastic model of the YF-23 that really caught my eye. Seemed like a good subject, since only two will ever be made.

So I start entering all the data and cross sections in the computer and came up with a 1/12 scale ship that looks pretty good. 43.6 wingspan, 67.3 OAL, 927 sq in wing area. Plenty of wing area, and room for the twin Midi fans, and 40 cells.

Anybody tried anything on this plane? I need some ideas for airfoils. Northrop always uses strange ones!! Where can I find the MH air foils?

I will probably build the first one in foam and cast off some molds for glass parts.

Gordon
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Old Sep 22, 2001, 06:40 PM
EDF Jet Jam 2015 , May 28-31
Kevin Cox's Avatar
St. Louis Intl, Missouri, United States
Joined Jan 1997
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It wasn't EDF but when the ATF program started not many were around This is something that I and a good friend worked on years ago, it was powered by a AF05 pusher prop. The biggest problem was getting the darn thing to rotate on takeoff this has also been a problem for a GDF model too! The airfoil was a homebrew semi-symmertical (thin). There was also some one in EFI that built a MF480 version.

<img src=http://members.aol.com/_ht_a/kcox854272/graphics/YF23.jpg>
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Old Sep 23, 2001, 02:19 AM
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Hi Gordon

Admirable project.

Try these sites:

MH site - more than just aerofoils: http://beadec1.ea.bs.dlr.de/airfoils/mhfoils.htm

Selig site - more 'foils than you'll ever want: http://www.uiuc.edu/ph/www/m-selig/a..._database.html
and if this site doesn't work, try this: http://amber.aae.uiuc.edu/~m-selig/a..._database.html

Incomplete guide to Aerofoil useage - list of 2000-odd planes and their aerofoils: http://amber.aae.uiuc.edu/~m-selig/ads/aircraft.html

Cheers

Gordon W
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Last edited by Gordon; Sep 23, 2001 at 02:23 AM.
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Old Sep 24, 2001, 03:08 PM
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Tucson, AZ, USA
Joined Nov 2000
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Mine has a 44" ws and I've started to cut parts. For me the hard part was designing in the landing gear and the snake ductwork. I've got the main gear pretty much set, but until I can find a Springair 600 nose gear, I don't have the nose gear figured out. Lack of Springair parts is also affecting my F3-H Demon.

Back to the F-23. I chose to make a semi-symetrical airfoil that's 1 1/4" thick. That is about 1" thicker than scale, but who cares. I can also get in the le & te flap servos and the aileron/air brake servo. Power will be 2 pros. Robert keeps telling me brushless on hundreds of cells, but I think Mega on 14 each. The slick thing is the missile bay becomes the battery storage area. The long wire runs still scare me for RF so I'll twist and maybe go with an optical system. Taileron servos are CS65 which have over 100 inoz of torque. Hope to have it flying for the Tucson Jet Rally in March. The main impression that I have of the plane so far is that it's big and it's going to be impressive.
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Old Sep 24, 2001, 04:42 PM
Flying Welder Pilot
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Reno, Nevada
Joined Jan 2001
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Bob Reynolds- Have you come up with a projected weight of the plane yet? Do you think the Spring Air 600 nose gear will support the weight? When I talked to spring air they kept steering me torwards the #301 slimline series (8 to 12 lb range). The heaviest part of my gear was always the 5/32 music wire struts and wheels.

This plane looked like an ideal short wire lead installation with the ability to run the batterys in between the fans and the fan units mounted more mid wing.

Kevin- Did your mock up fly off bungee at all? I wonder if gear placement has to change to get the plane to rotate?

My father worked for Northrop for many years, but I never knew what he worked on until he retired and told me he worked on the F 18 and B 2 projects. Everytime I tried to model any of the newer projects like the B2 and this YF-23 the airfoils always stopped me dead in my tracks. Do we have any Northrop Aerodynamic guys on Ezone??

There is nothing wrong with big and beautiful. It is more like "A whole lot more thrill factor"

Gordon
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Old Sep 24, 2001, 08:29 PM
EDF Jet Jam 2015 , May 28-31
Kevin Cox's Avatar
St. Louis Intl, Missouri, United States
Joined Jan 1997
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Quote:
Originally posted by Plane Crazy

Kevin- Did your mock up fly off bungee at all? I wonder if gear placement has to change to get the plane to rotate?

My father worked for Northrop for many years, but I never knew what he worked on until he retired and told me he worked on the F 18 and B 2 projects. Everytime I tried to model any of the newer projects like the B2 and this YF-23 the airfoils always stopped me dead in my tracks. Do we have any Northrop Aerodynamic guys on Ezone??

There is nothing wrong with big and beautiful. It is more like "A whole lot more thrill factor"

Gordon
Gordon,
I think this model was built in 90'-91', we didn't use bungees then
We relocated the mains but this bird was really sticking to the ground. It required a really nose high stance to get it to rotate. Since my friend was the head guy on this project (model) he didn't want to change too much. I would have moved the gear even more forward and went with all moving stabs.

My dad also worked on the YF23 but on the assembly line. I still remember asking him what he was working on but he wouldn't say It wasn't until he brought home a coffee mug from MDC that I could see what it was. The cup had a cloud and ATF lettering, when you poured in hot fluid the YF23 would appear out of the cloud.....pretty cool !
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Old Sep 24, 2001, 08:29 PM
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Tucson, AZ, USA
Joined Nov 2000
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Hi Gordan - Probably around 8~9 pounds fully batteryed. My Demon used Robart 15 retracts with the 1/8 gear legs with no problems. I don't see why Sprinair with aluminum frame can't match Robart plastic.

Not a short wire lead plane. Two feet from rear of fans to center of missile bay/battery box, three feet to the canopy/receiver. As the fans move forward your main gear will start to interfear and worst of all the inlets become really contorted as they move inboard and up. The inlets on this plane are not fun items.

Essentialy, at this scale, the wing profile is the equivalent to a quarter inch flat plate with funky twist and camber in funny spots. I don't care about being scale in this area. I do care about the large amount of taper and the possibility of tip stall.

Please ask your father about the A/F-2 "Thunderchief II" as published in the Jan 1994 Issue of IEEE AES Systems magazine. This is essentialy a single engine F-23 that the artical authors said that they wished had never been published (I called Northrop and spoke to B Bartels, one of the co-authors). He said that it went futher than just the artical (there is speculation that one crashed in Britan). I would like more info (a 3-view with sections would be nice) so that I could model this aircraft.
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Old Sep 24, 2001, 11:01 PM
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MicroRotors's Avatar
USA, CA, Hesperia
Joined May 2001
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Hello Gordon,

Well ,,, Yes someone has done this plane and a big one at that. Twin fans and she weighs in at 20 pounds dry. I belive this one was made from glass and carbon fiber. It hangs in our shop as this one was made by my employer and he also worked on the real ones at northrope. He goes by the name Glasairallen here on the zone.

He dug out the the molds on friday and is planing to make short kits I belive. If you would like I can get him to post more pictures of it and you can pick his brain for info. You can contact him through my work at http://www.rdtechservices.com
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Old Sep 25, 2001, 12:16 AM
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Melville Saskatchewan Canada
Joined Mar 2001
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yikes that's huge You would have to stand clear of the intakes on that one heheheheheh
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Old Sep 25, 2001, 12:20 AM
Flying Welder Pilot
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Reno, Nevada
Joined Jan 2001
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Quote:
originally posted by Kevin Cox until he brought home a coffee mug from MDC that I could see what it was. The cup had a cloud and ATF lettering, when you poured in hot fluid the YF23 would appear out of the cloud.....pretty cool !
Oh no!! I got one of those cups also but with a B2 on it. Imagine how many Northrop fathers gave their kids those cups.

MicroRotors- yes I would be very interested in seeing and hearing more details. Did the big monster fly?? Thanks for the info and link.

Gordon
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Old Sep 25, 2001, 02:10 AM
I'll fly anything...
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United States, CA, Palm Springs
Joined Aug 2001
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YF-23 Black Widdow

Hello, I'm the nut that built that huge (1/10th Scale) ducted fan YF-23. While at Northrop I worked on many wind tunnel models of the YF-23 at various scales (1/20th thru 1/8th) as well as a full scale RCS (Radar Cross Section) model.

For those that are curious about the airfoil used on the 23, forget it! It's not relevant at this scale. The actual airfoil that was used is abaout 8"-9" thick at the thickest point at the root. So for a 1/12th scale model that would mean that the wing would be about 5/8" thick at it's thickest point... this simply won't work at this scale (unless you can modify the laws or physics or otherwise tweak the Reynolds numbers of the flight envelope of your model). Keep in mind that full scale wings for supersonic fighters are designed to operate in a very different environment than our models ... the rules are not the same.
The thickest point on my 1/10th scale ATF wing is about 2 1/2" thick instead of the .800" it "should" be.

For those that want a great education in model aircraft aerodynamics (and aerodynamics in general) I suggest Martin Simons' book which you can get at Amazon.com by following this link. http://www.amazon.com/exec/obidos/AS...536826-9250503

On another note I am currently working on CAD drawings for 2 more YF-23, these two are for EDF:

First model will be a tiny little thing for tiny 44mm (KP Aero Models) fans will have a wingspan of 13.92" and a length of 21.80"

The second model is for 3" fans (WeMo) and will have a wingspan of 23.02" and length of 36.12"
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Old Sep 25, 2001, 02:37 AM
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Quote:
Originally posted by Plane Crazy
Everytime I tried to model any of the newer projects like the B2 and this YF-23 the airfoils always stopped me dead in my tracks. Do we have any Northrop Aerodynamic guys on Ezone??
Gordon
If you look at the "Incomplete Guide ...." site I posted above, you'll see that most modern jets use the NACA 6-figure aerofoils, eg (Northrop YF-17 which became the F-18 (listed under Boeing as they must have got a production contract), G-D F-16, Boeing (!) F-15.

The Northrop B-2 is quoted as a "modified upercritical" section whatever that is, but no doubt the F-111 sections would do. No doubt the site owner can explain what a supercritical section is - it's probably a modified NACA 6-figure profile.

You can plot any of these sections as well as designing the whole wing, including structure or foam-cutting templates, using Compufoil, which has a NACA aerofoil generator built-in.

A friend of mine who's designed many GDFs, some of which have been kitted, always uses an 8-10% thick NACA 6-figure 64A0xx section, even on things like the MiG 15, and the models do have very good handling.

Cheers

Gordon W
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Old Sep 25, 2001, 11:17 AM
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Las Vegas, NV
Joined Dec 1996
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Hey GlasairAllen, there was a company in California I think back in the early 90s that offered various sizes of kits for the YF-23 and YF-22, I think in glass and foam form. Did you know those guys? I remember seeing the adds in Model Airplane News for about two years or so then they disappeared. I never did send off for any info. I'd have to dig out my old MAN issues from that time period. I think the company may have been called Starjet?

Yeah, glass kits for EDFs would be cool.
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Old Sep 25, 2001, 11:25 AM
I'll fly anything...
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United States, CA, Palm Springs
Joined Aug 2001
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Quote:
Originally posted by Ed Waldrep
Hey GlasairAllen, there was a company in California I think back in the early 90s that offered various sizes of kits for the YF-23 and YF-22, I think in glass and foam form. Did you know those guys? I remember seeing the adds in Model Airplane News for about two years or so then they disappeared. I never did send off for any info. I'd have to dig out my old MAN issues from that time period. I think the company may have been called Starjet?

Yeah, glass kits for EDFs would be cool.

Ed,

I remember George Miller making a YF-22, but I am not aware of anyone making a YF-23. I remember George and myself eyeing each other's planes at the Arizona Jet Rally back in 1991. I'm pretty sure that there has never been a commercially available kit of the 23 ... I could be wrong, but I've never seen it.
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Old Sep 25, 2001, 01:42 PM
Flying Welder Pilot
Plane Crazy's Avatar
Reno, Nevada
Joined Jan 2001
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GlasairAllen-Sounds like you are really ahead of the game on this one. I would definitely be in line for a YF-23 if it was scaled for Midi Fans.

Currently I have a Viewpoint data model of the YF-23 that I have been converting from polygons to nurb surfaces so I can get it into Solidworks CAD. I really wanted to get everything in the computer so I could create all the ducts and parts once with out the trial fit and change design philosophy. A vendor owes me some time on a 3 axis router to cut some rim shape foam plugs.

Can you give us an idea of how the YF-23 flight characteristics are?

Gordon
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