Talk:Grumman X-29/Archive 1

Archive 1

F-5 connection

According to this link in the article, http://www.fighter-planes.com/info/x29.htm:

The two X-29s were built to test a forward-swept wing of composite structure. The X-29 incorporates the forward fuselage of the F-5 and the landing gear of the F-16.

This agrees with other sources I have read over the years, at least one print source of which I still have. The "forward fuselage" (basiaclly the cockpit to just aft of the nose cone) is hardly the "airframe". From what I have read, the X-29 was a new design which just used existing structures which did not need to be purpose built, including the main gear of the F-16. I certainly hope the X-29 doesn't show up on the F-16 page as a variant, or even in related content. However, I have no problem listing the F-5 under Related development in the Related content section. - BillCJ 20:50, 17 January 2007 (UTC)

Personal note

I used to make TDY trips to Grumman, for systems-level verificaiton tests. I was able to see/touch the X-29 #2 ship at Calverton sometime in the mid-80s. Until #1 was doing well in flight test, Grumman would not allow this. I felt privleged!

Also, there was a cartoon of the X-29. The crew chief, unfamiliar with forward swept wings, tells the test pilot "They put the seat in backwards, Sir, so I had to turn it around." —Preceding unsigned comment added by 205.175.225.22 (talk • contribs) 18:01, 30 July 2007

Aeroelastic Considerations

Fnlayson, you left a note about whether the AIAA reference applies to both paragraphs in the aeroelastic section I added. Yes, it does. What's a good way to indicate that? Just repeat the reference after both paragraphs?

The AIAA reference is available online through a Google Books preview, but I'm not sure if it's proper to put a link to the site. Is the Google Books preview static, or does it randomly select pages to remove? This is the link to the first relevant page: Performance, Stability, Dynamics, and Control of Airplanes‎.

I found another good source, NASA Technical Memo 100445, Current Flight Test Experience Related to Structural Divergence of Forward-Swept Wings. There's some info about the aerodynamics that create the divergence in the introduction, and probably some more encyclopedic info for anyone who cares to comb through it. Might take a look myself one day.

There's also a Popular Science article from 1980, also available in Google Books (apparently not as a preview, but the full issue): Wrong Way Wings Aid Maneuverability of Supersonic Planes. It's maybe more accessible for the average reader, and does a decent job of explaining the aerodynamic bending/twisting coupling, but it doesn't really capture the effect in the composite material. Does it make sense to add one or both of these references? Khakiandmauve (talk) 07:25, 13 February 2009 (UTC)

I must have forgotten about this. I fixed the AIAA reference to the first paragraph. I removed the decrease in buffet sentence from above the Aero section. -Fnlayson (talk) 18:34, 28 May 2009 (UTC)

Folks-Back in 1983 I was conducting research into FSW fighters at Cranfield. Sometimes I taught aerodynamics too. There are some points that need clarification.

1. All swept wings experience flow components along the wing. This means that the Boundary Layer is pushed downstream. On rear sweep with ailerons, roll control is lost FIRST in the stall, meaning (fatal) loss of control at high Angle Of Attack( AOA ).
2. FSW roll control is retained post-stall, which make FSW desirable in a fighter.
3. Wings bend like a ruler under load. Rear sweep bending reduces the AOA of the outer wing, so reducing loads. FSW tips have an increased AOA and so structural divergence is possible.
4. Anisotropic structures made of GFRP or CFRP use the fibres to turn the bending into a rotation so producing progressive wash-out and preventing divergence.
5. This results in the possibility of a wing with forward sweep for an acceptable wing weight penalty.
6. The X-29 further integrated the Close-Coupled Canard into the design, whereby the downwash from the foreplane suppressed the stall at the inboard portion of the wing(which was the rear part) by producing locally reduced AOA.

I could tell you more, but I'd have to eat the internet. -Simon O'Riordan —Preceding unsigned comment added by Simonoriordan (talk • contribs) 22:34, 17 January 2010 (UTC)

"In Popular Culture"/Videogames

The X29 appeared as the Grumman F29 Retaliator in the 1990 PC/Amiga game F29 Retaliator, published by Ocean Software. I don't know if this is relevant enough for inclusion in the article, but I think I have seen some articles on aircrafts mentioned appearances in various video games and TV shows, and to my knowledge, F29 Retaliator is the only "official" video game appearance of this aircraft (though it also appeared in various unofficial mods for Microsoft's Flight Simulator series). —Preceding unsigned comment added by 213.89.231.149 (talk) 22:51, 15 February 2009 (UTC)

Thanks for taking the time to ask first. It has to be a notable appearance to be added. Also, for this one need a reference saying it is really a X-29, vs. people saying it looks like one. See WP:WikiProject Aircraft/page content#Popular culture for more info on guidelines. -Fnlayson (talk) 00:07, 16 February 2009 (UTC)

So, the X-30 Conquest in the GI Joe:A Real American Hero series was a design unrelated to the X-29? — Preceding unsigned comment added by 75.91.233.95 (talk) 01:10, 3 November 2014 (UTC)

Decrease in Buffetting

Fnlayson, decrease as compared with what? Other forward swept wing aircraft operating supersonically? Conventional aircraft in the transonic region? Khakiandmauve (talk) 17:08, 28 May 2009 (UTC)

I didn't write it, just changed to a more likely term. Since the X-29 has a forward swept, that's probably compared to a regular swept wing fighter. -Fnlayson (talk) 18:22, 28 May 2009 (UTC)

The statement on "buffeting" is very vague: Buffeting from stall or buffeting from high Mach? Also, what to compare it with ? You can only compare it with a rearward swept plane with same aerodynamic profile, same wing area etc. Also, the electronic flight control system will surely play a role in evening out any "rough" behaviour of the aircraft... so is it really an aerodynamic effect ..? In any case, a source should be provided.--Iediteverything (talk) 18:30, 28 May 2009 (UTC)

Dynamic instability

A sentence in the article states that "the wing configuration made the craft inherently unstable". This statement can easily be misunderstood in the way that one might think the rearward sweep rendered the aircraft unstable. However, the instability is only due to the relative positions of CG, canard and wing. I propose to clarify the statement.--Iediteverything (talk) 19:28, 28 May 2009 (UTC)

Some clarifying would be good. But there are other articles to really explain what unstable/instability means. Articles such as Relaxed stability, and Longitudinal static stability are some I found on this. -Fnlayson (talk) 13:13, 29 May 2009 (UTC)

I agree. Also, as canard architecture would allow to have an orthodox stability with both the main wing and the stabilizer concurring to the lift (one of the many reasons to use relaxed stability with a standard geometry is to avoid the negative vector of the stabilizer push reducing the overall lift), the choice of making the aircraft using a relaxed stabilty model stems probably out of the wish to get the plane the most manouvrable possible, and is completely a designer choice.By the way, forward swept wings affects a little the directional stability, but it's nothing that requires anithing more than a bigger rudder. There have been some canard planes (starting with the Wright's) as well as some (moderately: torsion is a bad beast on these wings, and require top-notch tecnique - else this plane wouldn't have been needed) negative swept wings planes way before fly-by-wire cames into existence.79.152.135.56 (talk) 18:54, 17 July 2009 (UTC)

Similarity in appearance to the F-20 Tigershark

Call me crazy but i think that the X-29 looks like an F-20 Tigershark with foward-swept wings and canards. - Blueteamguy

Hmm, interesting observation...the resemblance is very striking. I wonder if the X-29 was based off the F-20 airframe? Would be interesting to find a good source connecting the two. — Huntster (t • @ • c) 23:03, 2 July 2009 (UTC)

The forward fuselage is from the F-5. This is mentioned above and in the article. -Fnlayson (talk) 23:17, 2 July 2009 (UTC)

And the F-20 was based on the F-5, hence the striking similarity. Beyod that, the rest of the fuselage, the wings, and the contral surfaces are quite different. There is commonality in the engine, as both aircraaft used the GE F404, and thus the exaust nozzles are similar, as is the size of the rear fuselage that contains the engine. - BillCJ (talk) 06:01, 3 July 2009 (UTC)

Citations needed eh?  :-)

The edit by Fnlayson at 02:48, 1 September 2009 installed two "Citation Needed" tags. I removed one "Citation Needed" tag that was put in place after I changed one uncited claim to another uncited claim. It seemed to me that often the criterion for a tag is a mere change that happens to get a citationist's attention. I don't think this is the way things should be. Indeed, I noticed that the whole article is without inline citations. I don't know why those two sentences were singled out in the edit for a tag. I had made other uncited changes (based only on my memory from three years flight testing both airplanes) that were not tagged. It all seems haphazard, especially in light of the whole article being citationless. Anyway, this is just my defense for removing that tag that was added to one of my edits. I hope it works!  :-)

--Gummer85 (talk) 08:27, 1 September 2009 (UTC)

Okay, I take some of that back, the article isn't as citationless as I portrayed it. I added a (cruddy) inline citation (to the spot where I had removed the tag) referring only to the "Aeroelastic" part of the article itself. That should be good enough. It better be, dang it.  :-)

--Gummer85 (talk) 08:44, 1 September 2009 (UTC)

I hate to tell you, but I had to remove the reference. We cannot, under any circumstance, reference an article on Wikipedia. It would be like a book on airplanes using itself as a source! If the citation used in that section is applicable in this particular spot, simply add the same citation here. — Huntster (t @ c) 09:08, 1 September 2009 (UTC)

Gummer, I'm not sure excalty what you think Fnlayson was doing, but he is a good editor, and is following proper procedure per WP:RS. And Hunster is right that we don't cite WP articles, nd that the proper way to do that was to cite the source used in that section, assuming it says that. That's hard to know, since Gummer edited the section without providing new sources. One must assume he actually read the source, and was making a clarifiction based on that source. Also, Leads aren't meant for long drawn-out explanations; that goes in the main text. I've this restored the origian Lead. If what it says is incorrect, then correct it, keeping it concise, or take it out. - BilCat (talk) 10:48, 1 September 2009 (UTC)

You rewrote content without providing a reference, so I tagged it and another uncited paragraph. See Wikipedia's policies on citing sources (WP:V, WP:CITE). In many cases cites can be omitted in the Lead because it is a summary (WP:LEADCITE). The text currently in the Lead summarizes content cited later in the article. Thanks for the help BilCat. -Fnlayson (talk) 14:18, 1 September 2009 (UTC)