SIG Mustang Stunter Plastic Parts

[Dan McEntee]

   I am doing some digging, cleaning and pitching in my basement and garage trying to get some more room and at least a hint of organization, and ran across a set of plastic parts for the SIG Mustang Stunter. You know, the parts that we always say to toss and replace with unobtainium wood that we can never find? I has handling these and thought, "damn, these really are pretty light." I grabbed my digital scale and weighed each piece. The top fuselage section weighed 39 grams, or less than an ounce and a half. The radiator scoop piece weighed 13 grams, or about a half an ounce. That really is pretty light for what they are, and a fair amount of work to reproduce them out of wood, and I don't know that you would get them that light or lighter? My concern would be in painting them, and making sure that whatever I painted them with would adhere well. I didn't have the lower cowling piece, but it's so small it has to weigh way less than the scoop. Just thought I would throw that out there for your consideration. I do hope to build at least one more of these and will consider using the plastic just to speed things up some. There is a heck of a lot of airplane there to save some weight somewhere else.
  Type at you later,
   Dan McEntee

[Clint Ormosen]

I don't think weight was the reason we tossed them, at least it wasn't for me. The part of the kit that made this plane so heavy was the solid foam wings, and maybe some not so choice wood that the kit contained. My two problems with the plastic parts were structural integrity (they twist and bend pretty easily) and putting the finish on them (which can probably be done just fine, but I was uncomfortable with my abilities).
So I tossed them along with the with the wing cores and used triple cored wings, better wood sheeting, and hollowed blocks for the scoop and fuse top. 40oz airplane.

[Glenn (Gravitywell) Reach]

So basically you replaced the kit and used the plans?

[Gary Dowler]

Dane, is this for the S2 kit?

Gary

[john e. holliday]

I built the SIG Mustang Stunter as soon as it got to me when I seen the ad.   Built box stock. Power was Fox .35 Syunt.  Finish was SIG dope.   Weighed 41 ounces and flown on .018 X 60 lines center of plane to center of handle.   It demise was the bell crank mount.  Came loose on third flight doing reverse wing over   Immediately built another one and second piece of ply wood on the other end of bell crank bolt.

[Clint Ormosen]

So basically you replaced the kit and used the plans?

Yeah, pretty much. Used Scott Smith Triple cored wings with carefully picked sheeting and the best blocks I could find to replace the plastic. I think the fuselage sides, formers, elevators, and a few others odds and ends are from the kit.

[Lyle Spiegel]

contact John Duncan or Bob Hunt to obtain triple cored wings. Use the plastic turtle deck as a form to mold a balsa turtle deck. Power with B-40/ OS40 FP or LA as alternate to Fox 35

[Doug Burright]

I have a complete SIG Mustang kit- foam, plastic and all. I haven't built it yet, as there are very few purple Mustangs- Voodoo Reno racer is one- however, I think mine will be modeled as Miss America.

Is excessive weight the reason modelers say that the performance of the airplane is poor? Would better balsa selection, and removing foam from the wing result in a satisfactory weight, to provide better performance?

The pictures are of a Mustang that I built, inspired by pieces left-over from a SIG Twister, when I modified it into a Fancherized version. I did something right, and this is a great flyer! The finish is Ultracote and Krylon.

[Dan McEntee]

    Hi Doug;
    You just need to watch the overall weight on a SIG Mustang. In stock, unmodified trim in can get a bit porky, but I think that is because when most of us first built them we didn't know much about building and finishing light. We know more about structure and such and how to better build that foam wing. Triple coring and careful selection of the balsa for the sheeting is the main thing. The plastic parts have gotten most of the attention over the years.  Most recent versions I have seen have had the tail stretched a bit, stab span stretched a bit and then put good reliable power in the nose. Do a search on the list here for Jim Lee's Mustang, as I know he has listed the specs for the couple examples that he has built and his were powered by a good old Fox.35. He has collected quite a bit of hardware with his. Just apply what we all have learned on this forum over the years and you will have a SIG Mustang DGA .  (Damn Good Airplane!)
   Type at you later,
   Dan McEntee
   PS to add:  One point I forgot to make ws that this is a kind of dsmallish airplane, and that is the reason to watch the weight carefully. In completely stock form and built like a typical newbie would, weight can get to 50 ounces pretty easy. If kept to 40ish or so, it has a thick enough wing to carry that weight well. The last one I did was 40 ounces with a 40 FP and flew every well for me.

[BYU]

Well as this post is about the SIG Mustang plastic parts.   .   

I have been kindly loaned plastic parts to make plaster cast molds. After making the molds and molding wood parts, I finally did a weight comparison.

The main fuselage top deck ABS part weighed between 39 and 49 grams in each case (I had 2 parts to compare)

The molded wood parts are made from 2 sheets of 5lb 1/16 wet molded together to achieve 1/8 thickness. They are laminated with water based wood glue during molding and they weigh 16 grams when dry.

Each part tells a similar story of the plastic parts being 3 x heavier than molded wood part.

In the case of the largest part you are adding an extra ounce at least, and a total of 2 ounces for all parts.

This plane is small and 2 ounces is equal to 5% of a 40oz plane. It's enough to care about in my book.

[Tim Wescott]

... and a 1/8" thick laminated deck is going to be a heck of a lot stronger, too, in just about every way that counts.

What did you use for glue, and how did you spread it thinly enough that it didn't make things too heavy?

[BYU]

... and a 1/8" thick laminated deck is going to be a heck of a lot stronger, too, in just about every way that counts.

What did you use for glue, and how did you spread it thinly enough that it didn't make things too heavy?

I use “Titebond Original” the water based one with the red label.

It is important that you wrap the mold in plastic saran wrap (cling film) or similar before you use this technique. For obvious reasons do not cover the wood or it will take forever to dry out.

Once the wood has been soaked in hot water for an hour or 2, it is pliable.

I drain the wood with kitchen towel and then put a lot of glue on one surface of the 1/16, literally paint the whole part. Then put the 2 sheets together with the glue in the middle of the sandwich.

The water still left in the wood tends to thin the glue and excess squeezes out as you wrap the bandage around the wood and mold. I mop up the excess glue with kitchen towel as I go and usually perform this weird ritual in a bathroom over sheets of newspaper, as it can be messy.

Surprisingly I have RARELY found the bandage to become glued to the wood (when dry), and the bandage peels away with very little harm to the wood. I use cheap 50 cent disposable bandages you can buy in packs of 20.

I theorize that as the wood becomes dry over 2-3 days, the glue sets due to the water evaporating from the wood, taking the glue's solvent (water) with it.

I have made maybe 40 parts this way and done a good bit of destructive testing to see if any parts hadn’t glued. As long as you heavily cover the parts in glue, it works well and you end up with a ridiculously strong part for its weight. I even make cowls this way now as it is stronger than a carved part and a lot lighter.

I am not enough of a scientist to explain why the part barely weighs more than the wood on it's own, but that's the way it always works out for me.

[Howard Rush]

Golly, I molded a part with Titebond like that once and it came out extremely heavy.

[Howard Rush]

Clint's Mustang was one of the best-finished airplanes I've seen.  I think this is it:

[Howard Rush]

Yes.  It soaked into the wood.  Could have used it for a cricket bat.   

[BYU]

Yes.  It soaked into the wood.  Could have used it for a cricket bat.

What's a cricket bat?

[Steve Helmick]

You and/or Tim can send me a mold and I will make you a part (using the above technique) for your evaluation.

What's a cricket bat?

A bat that feeds on crickets, obviously. They can be trapped, if you are careful to wear a fox hat.  Steve

[Dennis Leonhardi]

For what it's worth, I spoke with Mike Pratt a couple of months ago about the Mustang Stunter.  He said it flew quite well with a stock Fox 35 Stunt engine.


Dennis

[John Park]

I've used that moulding technique with success over many years, and get my best results with an old-fashioned casein woodworking glue in the form of a powder that you mix with water - the Trade Mark in Britain is 'Cascamite', if you can still get it (I have a big can that's lasted me twenty years or more).  Its two advantages over PVA glues are that it's extremely light once dry, and that it sands like balsa - it is much superior to PVA in this respect.

John

[Scott Richlen]

I built one many, many years ago and it came out pretty, but heavy.  But I always liked the looks.

I have the kit and it is on my building list.  In addition to molding the plastic parts from balsa, I also plan to use the kit's original foam wing so it will come out really light!

What?

Yep, I'm going to chop it up and use it to make a lost-foam wing Bobby Hunt style!  Use one wing panel to chop up for the rib forms, and the other panel to mold the leading edge.  Build it in the core shucks.  Is that a great idea or what?

Use Todd Lee's recommendations for modifications.  It'll be great.

Oh yes, I have an OS 35-s to power it with.