Building a reproduction of the Goldberg Ranger 28

[PaulBrad]

There were some excellent rubber powered Free Flight models in the 50', 60's and 70's aimed at the less experienced modeler. One was the Carl Goldberg Ranger 28. This model uses a tissue covered balsa framework, but is some what unique in the construction. The fuselage is built from die cut pieces that fit together like a jigsaw puzzle. It is like a hybrid between the all balsa sheet models developed by Carl Goldberg for his Goldberg kit line and those of Top Flite under their Jigtime series.

I was able to acquire one of the old Goldberg Ranger 28 kits a while back with the intention of developing a reproduction. I have finally been able to do the reproduction drawings. With a 28" wing span this model is excellent for introducing a less experienced modeler to the world of tissue covered open framework models. The wing and stab are only covered on the top. That reduces the work load and helps keep the model light.

I just completed building the proof model from my drawings and will share the process here. I will provide a link to the plan/parts package at the conclusion of the build summary.

Paul Bradley

[PaulBrad]

The build begins by cutting out all of the parts. There are quite a few due to the fuselage structural design. The original kit plan did not include a profile drawing of the fuselage to help with the assembly of each side. The kit depended on the precision of the die cut parts to achieve an accurate assembly. My reproduction does include a fuselage profile drawing to make sure each side is the same when assembled.

After the parts are all cut out assembly begins with the fuselage. The steps are summarized in these photos.

Paul Bradley

[PaulBrad]

The fuselage assembly goes fairly quickly once all of the parts are cut out. That is one of the hallmarks of this model design. Once the fuselage is completed the flying surfaces are assembled.

The wing and stab use a somewhat unique rib design that requires a little finesse during the assembly. Essentially each rib gets supported by pins after placing them over the plan. The leading and trailing edge strips are then glued in place. It looks a little fussy but is actually easy to accomplish. The resulting structures are quite strong and can handle the flight loads event though they only get covered on the top side.

Paul Bradley

[PaulBrad]

When the flying surfaces are completed everything gets sanded. The original kit built model used a vacuum formed nose piece to support the prop thrust bearing. That is not really necessary. The reproduction model has a removable nose block to make stretch winding easy.

Once the airframe is completed it is covered with tissue. I used the colors shown on the kit plan for the proof model. No real effort was made to dress up the model with tissue trim. To help avoid major warps in the wing and stab, the tissue on those surfaces is not water shrunk. I used Future floor finish to seal the tissue on the flying surfaces. The fuselage and fin tissue was water shrunk and received a coat of 50/50 clear dope followed by a coat of Future floor finish.

The completed weight of the model is 42.2 grams (without the rubber motor). I used rather heavy wood and domestic tissue for this model. Lighter wood and tissue would take off some weight. It should fly nicely as a sport model, and that is the intended purpose of this nice design from Carl Goldberg.

The reproduction plan/part package is a free download from my web site at http://www.parmodels.com. Just go to the downloadable plans section.

Paul Bradley

[Work in Progress]

I remember these from when I was a kid, but never had the money to buy one. That doesn't seem a bad weight, considering the materials.

[PaulBrad]

Just a quick note to let everyone know that Brian Malin of BMJR Model Products now has a laser cut kit available for the reproduction Ranger 28. This is a full kit. It sure does save a lot of work cutting out parts. The BMLR web site is located at http://www.bmjrmodelproducts.com.

Paul Bradley

[kevin matthews]

Pretty neat. So you can cover a coat of dope ( 50/50 ) with Future Floor Polish? I'd welcome something that wouldn't bother my neighbors living in an apartment building - management, too. Can it just be brushed on? Does it need to be thinned?

Kev

[Megowcoupe]

Hi Paul

Good news on the kit version- that just made the decision a lot easier! I built a couple of these when I was younger, never got them to fly because I kept on doping the wing tissue and had a propeller to deal with.

However, it's not on the website yet. I've got to pick up some stuff from Brian- this one, the Hog, and a new fuse for my Race E.

Thanks for doing this- much appreciated!

Sam Brauer
Stamford, CT

[glenn2626]

I believe BMJR is at

http://www.bmjrmodels.com

I built one of their Jabberwock Jr kits and was very pleased with the quality of their kit AND the finished product.

But I can't find your Ranger anywhere on their site.

[PaulBrad]

Kevin - The Future floor finish will go over just about anything. I have used it to seal water slide decals applied to heat shrink film covering. It brushes on very nicely. The tissue on the wing and the stab of my Ranger 28 had Future brushed on the tissue. I rubbed it on the fuselage to allow for a thinner coat since it already had a coat of 50/50 dope. The fuselage application was just to help even out the look of the finish. I am just starting to use Future on tissue but so far I really like the results.

Glenn - thanks fore the corrected BMJR URL. I should not post when I am tired. Brian sent me an e-mail several days ago and indicated he was in the process of completing the first batch of kits. I guess he has not yet updated his web site. I would imagine an e-mail to him via the web site would get you the price and if acceptable would get one in the mail to you.

Paul Bradley

[kevin matthews]

Paul, Thanks for the information. I think I'll try it.

Kev

[haddy52]

just built this one of net plans a4 sheets need to be lenghtend 4in uhu glue traced freehand causing errors used silk tissue from hobby shop on stab first it was crushed by morning. nearly gave up. built a new stab tried domestic colored tissue which worked well accept for building errors.waiting for rubber, prop. very hard to get, Haddy

[PaulBrad]

Looks nice Haddy. It should fly well when you get your prop and rubber.

All the best,

Paul Bradley

[groundlooped]

G'day Haddy,nice model, for rubber and props(or anything free flight) Peter Lloyd in Melbourne www.Pel Aero Products.com :)
re:printing Paul's plans,--- disable the shrink to fit option on the printer, carefully attach the extra 4" of A4 paper, I use invisible scotch tape,on the reverse side of the page and on printer menu set for 'letter'or 'legal' it should print out ok,you can also attach tissue to a backing sheet and carefully feed through. :D

[haddy52]

a picture of first attempt this tissue cost $9 to strong i used $i.20 for 5 sheets from paper shop some nice colors.on test flights plane floats strait.it may fly away.Thanks to paul for the drawings inspired me to build again.my fuse ended a bit short aft end had difficulty securing stab.Thanks again Paul Bradly.

[PaulBrad]

I had an opportunity to build one of the reproduction Ranger 28's from the BMJR laser cut kit. It sure was nice not having to cut out all of the parts for this build. Final weight of the kit built models is 36 grams. Much lighter than my razor cut prototype. The kit wood was very nice and I used lighter tissue for this example. The tissue color and markings were applied with my ink jet printer. I also added a DT to this model. It will not take much lift to lose it to Hung, so the DT was added. That was a very easy mod. A viscous button timer controls the DT.

Paul Bradley

[wingbeat]

Well done- looks great.
Did you start with white tissue?
Would you post detail pics of your DT set-up?
thanks

[Konrad]

Pail ,
Very very nice!

I have to ask, how are you dealing this the laser char? I don't see any of those ugly brown marks in your yellow trim.

I find that if I sand the char off with 400 grit sand paper that it takes me just as long to build a laser kit as to hand cut a kit. Also sanding off the char often looses that "great laser fit".

What am I doing wrong?

all the best,

[PaulBrad]

wingbeat- I do start with white tissue when doing ink jet printed tissue. All color is applied with the printer.

I have added some photos of my DT set up. One thing that is required with the button timers when using them on models the size of the Ranger 28 is an arrangement for handling stronger rubber bands used to pop up the stab. If not done the timer trips much to fast due to the added pull of the pop up bands.

The arrangement of the Ranger 28 stab and fin made it easy to add the DT function. The fin slot is already in the top sheet part. A plywood stab saddle was added to support the stab since it is not glued in place. The stab was also set up to be easy to remove for transportation. The DT line just unhooks from the hook on the stab. The balsa on each side of the stab hook keys the stab in the fuselage when it is pulled down to the flight position.

Konrad- I first assemble the model without removing any of the laser burn from the parts. After assembly I lightly sand the edges that will show through the tissue. That way I am not spending time sanding edges that will not show. This makes it pretty easy to clean up the edges and does not take much time.

Paul Bradley

[wingbeat]

Thanks Paul-
that's very helpful.
Great pics and explanation.

cheers,
'beat

[Megowcoupe]

In terms of laser char- I've heard that some folks like hydrogen peroxide. I've just never found it to be a big deal though.

Sam

[haddy52]

I have got my rubber and prop, but am having having trouble getting the loops exactly the same length (4 loops of Tan rubber) Some suggest rubber should be half as long again as rubber from tail anchor to prop hook.Any advice?

[PaulBrad]

haddy52- When I make up a multiple loop motor that has an even number of loops I start with a single loop. I then fold it in the middle to go from one loop to two loops. A four loop motor gets folded again. The length of starting single loop motor is determined by the appropriate number of multiples of the desired final motor length. By folding a single loop motor you are able to get all the loops the same length.

Paul Bradley

[haddy52]

Paul i tried that i nailed two nails 440 mm apart and wound rubber around carfully loops extend 2.5 inches past nose. have tried 200 turns,rattles at the end.Flying next,have you tried yours.haddy.

[PaulBrad]

I have not had an opportunity to fly model number 2 yet. Due to weather in my area I may not get to fly the model until the spring of 2010. My first model is flown on a singe loop of 1/4" rubber. I wind that motor to 1,100 turns. It can take more but my flying site is pretty small. Flight duration for that model in late evening air has been 50 seconds. Duration would be longer with more turns and a braided motor. The motor tends to bunch at the rear of the fuselage near the end of the motor run and that causes the model to stall in the glide. That is actually good as it helps keep the model on the field. The new model being lighter should have better duration. Hence the addition of the DT.

Paul Bradley

[haddy52]

Paul i flew the ranger hand launched it climbed rapidly into a breeze,summersaulted overhead about 30ft then flew with the breeze in a series of shallow stalls vering to the left its last stall timed just right for a 3 point landing.It needed a small amount of lead for trim might need a bit more,on test glide it flew level there is built in warp in stabiliser, tissue warp.
I built the plane from 3/32 balsa they didnt have 1/16 so it is probaly a bit heavy by comparison. Second flight i cranked it up to 300 turns and bang something gave way the rubber twisted of prop hook and broke tissue down one side of fuse nothing serious. Still having trouble getting rubber loops exact same length.What is a braided motor.
Haddy.

[Trisquire]

I had a Goldberg Ranger 42 as a kid. It was a foam RC ARF, but I can see the family resemblance.

Tom