Grumman X-29 (Dragon-4643) Micro PMC conversion.

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Micromeister

Micro Craftman/ClusterNut
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The Grumman X-20 has to be one of the Sexiest Planes every designed. Super KEWL Swept forward wings with forward canards.
I've admired this plane since first seeing it years ago. Last year actually in November I noticed Dragon had produced a 1:144th scale "Warbirds series" plastic model kit. I just had to have one.
A week or so later the package arrived at the house and I opened it with great hope of converting it for MMX flight.
UGH! alas this little 1:144th model was Way to small to accept the minimum diameter T2+(.281") motor tube. and the over all model was only about 4-3/8" long including the aerospike (4-1/8" without).
Dejected I re-boxed the kit and put it aside to work on a bunch of other Micro PMC's I had in the Que.

About a week ago I again was lured to the X-29's sexy design boxtop.. and again Opened it up to really take a hard look at what it would take to make it fly.
Still WAY to small for the required T2+ Body/motor tube I decided some major body surgery was going to be needed both outside and inside this little model to have any chance of converting it. Removing the Aft fuselage at the second panel line while filing out in styrene with a round file to paper thin wall thickness just barely passed the body tube. This left a long distance from the Body Panel line just behind the cockpit to the aft end of the main Landing gear bay for a T2 shoulder. Adding about 3/8" to the needed extension length our shoulder was epoxied into the now seperated Nose section inside the Air intakes forming a natural locking system.
Complicating getting our T2+ in the aft end of the model was the fact the bottom fuselage panel included the Main Landing gear bay recess which had to be all but ground through to pass the tube. Extending the T2+ out the back to where the model exhaust nozzle would have been only gave a total T2+ length of 1-7/16".
Since the Main gear bay had been more or less saved I decided to make this model a wheels down configuration.

Due to extremely limited space I had to cut the Shock-line down to 28" of 70lb kevlar with a 1/4" x 6" orange PTFE Streamer/Wadding. Yep I got it all in there LOL!!!
Our Cardboard Cut-out showed the model would need about 4.1g of Nose weight. 4.1g! even using #9 lead shot that was a lot of tiny balls. I Hollowed out the cockpit putting in a false bottom, after gluing up the forward wheel well and gear it was all be ground off from the inside. The interior styrene walls were thinned as much as I dared. filled every tiny space with Shot. I even added a lay of shot to the exposed surface of the cockpit, covered it with epoxy and sanded smooth adding one last shot as the pilots head. Looks like it should be stable with a MMX-II motor.

Dragon did a outstanding job of detailing the landing gear, alas I was afraid the tiny spars would not take flight landings so a rear reinforcing plate of .005 waferglass (G10) was epoxied to the main gear and carefully filed to profile.

That's about as far as i've gotten on this little project.
Since I really didn't think I was going to pull this one off, I didn't take many progress photos while working through the problem areas...My Bad, Sorry. but I'll try to be a little better as the finishing and decaling go along.

With all the nose weight this little 4-1/8" model already tips the scale a 10.3g, Should be an interesting little flying Micro PMC.

Heres the Pics I have so far:)

MM 412uc01a_ X-29 Dragon #4643 PMC BoxTop($10.16)_11-06-14.JPG

MM 412uc02b2_Grumman X-29 Inst Sheet-b_Scan_04-10-15.jpg

MM 412uc02c_Grumman X-29 FS Color Decals_04-10-15.JPG

MM 412uc03_X-29 Cardboard Cutout_04-12-15.jpg

MM 412uc04a_X-29 SideTop Main parts assembled_04-13-15.JPG

MM 412uc04b_X-29 Bottom Main Assembled_04-13-15.jpg

MM 412uc05a_X-29 NoseWheel Sep Section Close_04-14-15.JPG

MM 412uc05b_X-29 Main LandingGear Close_04-14-15.JPG

MM 412uc06_X-29 NC & Body Sep, Shockline&Streamer_04-16-15.jpg
 
Have to agree:
I'm a bit concerned about the forward wheel but the tandem rear wheels are pretty much solid epoxy struts now:) This one will never be entered in any PMC contest so I wasn't very worried about "filling in" some of the landing gear weak spots.

Over the last few days have finished the build, rough sanded the primer, rather messy re-scribing the panel lines, base gloss white paint, decaling, final Krylon UV Matte clear and clear canopy adhearing. all in all with 4.1g of lead nose weight this tiny 4-1/8" model is 10.0g with a 1/4" x 6" PTFE Streamer/wadding. LOWt: should be 11.1g. so it should be a fairly nice flying PMC and cleaned up pretty well:)

MM 412uc07a_X-29 Primer Sanded, re-Scribed Panels_04-20-15.JPG

MM 412uc07b_X-29 Gloss Base White_04-22-15.JPG

MM 412uc08a_X-29 HandPaint Cockpit Details_04-22-15.jpg

MM 412uc08b_X-29 HandPaint Bot details_04-22-15.JPG

MM 412uc09a_X-29 SideTop Decaled_04-24-15.jpg

MM 412uc09b_X-29 Bottom Decaled_04-24-15.jpg

MM 412uc10a_X-29 SideTop UV Matte Cl. & Canopy_04-24-15.jpg

MM 412uc10b_X-29 Top UV Matte Cl. & Canopy_04-24-15.jpg
 
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I don't frequent this topic but that is really neat!

I've never done a PMC before. If you don't mind me asking: Is the vertical stab enough to keep it flying straight? Do the lowered landing gear affect the flight? How about the wing airfoils? If the fin surface is insufficient, do these things tend to cone on the way up?

Any general tips for PMCs as well as for jet-styled rockets & oddrocs? Thanks.

Looking forward to a flight report!
 
I don't frequent this topic but that is really neat!

I've never done a PMC before. If you don't mind me asking: Is the vertical stab enough to keep it flying straight? Do the lowered landing gear affect the flight? How about the wing airfoils? If the fin surface is insufficient, do these things tend to cone on the way up?

Any general tips for PMCs as well as for jet-styled rockets & oddrocs? Thanks.

Looking forward to a flight report!

PMC "Plastic Model Conversion" is one of the specialty Model Rocket Contest catagories frequiently flown at NAR Sanctioned competitions. PMC has it's own set of "pink book" (Mod-Roc Sport Code) rules. which should be read a couple times before venturing into this fascinating realm of the hobby.

To answer your first question Yes the Vertical stab or Rudder is plenty to keep the model flying straight and true off the pad. Because we are moving the CG allowing the Wings to act as fins most all the other flight surfaces only add to the stability. Generally the Lowered landing gear does not adversely effect the flight other then lowering the achieved altitude. External stores and lowered landing gear do add lots of static points and Lack of damage after flight can add to extra flight points as well.
In most Plastic models the airfoils do not really cause much in the way of lift, on some model is it adventagous to cant an elevator or rudder very slightly to create a slow barrel roll on the way up. If done correctly and is given in advance to the judges can add flight points to your score. For sport flying PMC's it just looks very KEWL:)
When working out the LCP/CG location using the cardboard cutout method I've never run into a model or situation on an Aircraft where the wings, Vertrical stab and elevators have not been more then enough "fin Area". On PMC's of Rocket, Missiles and Spacecraft many times clear lexan fins are used which do not count against the models outline score. However the attachemment method and appearance DO count as this is a craftsmanship evert.
As for coning on the way up....Rarely. however missing the proper LCP/CG location can cause almost instant "Re-kitting" or why many competitors Call this event "Plastic Death". I am one of those who would like to see the rules changed slightly to have the models flown first and judged for static points After a successful flight. I'd also like to see the rules require some sort of Proof that the PMC model presented HAS already made a safe and stable "test flight" proper to being entered in a public attended, Sanctioned NAR contest. This would GREATLY reduce the number of totally unstable entries that are currently seen when PMC is flown. It is my practice to ALWAYS test flight potential PMC models in Isolation by myself to ensure I've worked out the flight part of the conversion before the model is finished and made ready for presentation at Local, reigonal or National NAR contest events. PMC while a craftsmanship event, is also on the edge of Odd-Roc status which needs much closer Safety Check-in procedures they your run of the mill Sport flying or Contest models:)

Plastic model Conversion is one of my Many Close to Favorite NAR competitions as well as just plain FUN Sport building & Flying. I have to say MOST folks don't fly Plastic model conversions just for sport....but I do...it is truely a blast!

Truely I could talk about PMC for hours. I'd suggest looking in the specialty "Galleries" forums, Look for Plastic Model Conversion under "Themed Rockets". There you will see pretty much the gamut of types, subjects and prototypes, Jets, missiles, rockets etc. There are even a few prop jobs the fly well as converstions:)
I'd strongly suggest as a first PMC any scale F-104 Starfighter wheels up configuration, it has to be one of the easiest and best flying PMCs regardless of size 144th to 1/18th scale:) Second place goes to the F-100 SuperSaber a little more involved then the F-104 but a good all weather flying PMC.
If you need additional info just drop me a line [email protected] I can give a lot more in-depth info and larger files from there;)
Hope this helps a little, below are a few examples of other types of PMC conversions that may spark your interest even further then these Micro Powered Jets. All have been flown at least twice each with the exception of the Corporal missile which has only had a "test flight".

090-sm_M48-A5 Vampire Tank Odd-RocPMC_03-02-91.jpg

165-sm_XFY-1 Pogo 48th PMC_12-09-94.jpg

170_F104-G-StarFighter-PMC_32nd.jpg

189a_PanAm SpaceClipper Orion PMC_07-07-96.jpg

397b_MM Little John & Launcher Complete_01-13-14.jpg

603-sm_Mars Liner-PMC-sm_144th_05-22-97.jpg

683uc19c_Snark SM-62 96th Right Above Decaled_03-03-12.jpg

684uc15b_Corporal Missile & support 40th Decaled_03-01-12.jpg
 
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Wow! Those are really cool! I really like the finish on those F-104's, especially that 1:18!!!

Thanks for the answers. That's great that the fin area is sufficient if the CG is up far enough for straight flights. I've been reading through the Themed Rocket PMC gallery and the following:

Since BAR'ing this year, I've yet to start building other than helping my kid with an Alpha III; I'll start with a standard 3/4FNC and work my way up. All this info is very interesting & will come into play later. Also, the club launches over concrete so the likelihood of re-kitting is very, very high!

I appreciate you taking the time to explain all this & will ping you when the time comes. Thanks again for all the info! :)

ps - The Macross Plus YF-19 and Macross VF-1 from Hasegawa would be interesting...

Edit: John McCoy Sr's NARHAMS PMC tech tips <-- I just realized this is you. How embarassing!!! :facepalm:

hase_yf19.jpghase_vf1s.jpg
 
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Great stories abound with the x-29. Nose came from a junked f-5, avionics got mounted in the gun bays. Cockpit panel was out of an f-18 i believe. They even left the redundant gauges in place, which was convenient when the pilot had an in-flight gauge failure. Legend has it he pulled out a screw driver and swapped them while flying.

I really miss Grumman. Was great as a kid seeing so much of their stuff flying around.
 
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