Guillows Piper Super Cub 95

[Ben Mullins]

Hi all,

Ever since I first steped into my local hobby shop and saw a guillows kit I thought, can we make it R/C. For me, being a teenager, A guillows is the cheapest way to make a model from a kit, a desire i've had for a long time. So It came to half term, and i went and bought the Piper Super Cub. Its wingspan is 24", not too small and not too big, it weighs almost nothing which is the problem, im going to have to keep it that way.

Heres the box, doesnt look like its changed in years

It wasn't untill after I glued in these skewy formers that I remembered about a thing called a set square

Here is the fuselage all completed, I've worked out that one of those gaps inbetween the stringers is a perfect size for two 3.7gram servos, for the rudder and elevators.

Im not sure where im going to put the hatch so I can get into the model yet, have to give that some thought.

Ben.

[David Ashby - Moderator]

Looks good Ben, and look forward to seeing how the project turns out

[Ben Mullins]

Moved onto the wings, Decided against Ailerons because I dont think ill need them on such a small model, and they wont do much for the flying characteristics. Also theres not really anywhere to put the servos if i was going to.

After glueing all the formers in, remembering the set square, i glued in the stringers. I have noticed that the slots for the leading edge and spar are far to small, in fact half the size they need to be, gggrrrr.

Now I have to sand the leading and trailing edges to get the shape i need, it's taking ages!

Next entry to come soon, Ben.

[Ben Mullins]

Hi all,

  I have not done much recently because of; school, hay fever and designing a glider for a comp (here's the thread). But what I have done is make the tail surfaces. I've made them as suggested on the plan but added cross braces for strength, im going to cover the control surfaces with card instead of tissue of balsa, because its what I had lying around. I've also made the hinges, not much work because im using some old Film from a camera, I hope it holds!

Sorry no pics, my cameras broken!

Ben. 

[dzeno kovacevic]

very nice model

[Ben Mullins]

I had a go covering it with tissue and dope and made a hash of it, so it went in the bin!

[Steve Wheeler]

Hi Ben,

 Sorry to hear that...  construction or flying problems are part of the learning process, so I hope you will try again.

 If you'd like to describe what you did that went wrong,  I'm sure someone would be able to help you sort it out for next time.

Cheers... Steve.

[Ben Mullins]

I may have soaked the tissue !

[Steve Wheeler]

Hi Ben,

At the risk of telling you what you already know:

One, [of many], method of covering with tissue is to cut pieces of tissue to appropriate shapes for the contours and apply unthinned dope over the frame at the edges of the piece. Let it dry a bit, then lay the piece in place and apply  thinner over the doped areas to soak through to reactivate the dope, and a gentle rub with a finger should stick it down.

For the adjoining pieces it's a good idea to apply a bit more slightly thinned dope to the overlapping edges before using thinner as before. If not satisfied with the result, it can be safely removed with more thinner.

 [Make sure you have adequate ventilation with all these fumes!]

To tighten the covering I use a 50/50 mixture of water and Isopropyl Alcohol...[get it from your Pharmacy, be prepared to explain why you want it , and try to look innocent!....]

This mixture dries very quickly... the alcohol evaporates and sort of dilutes the water....I just lightly brush it on with a wide soft brush. Remember to pin down wing and tail surfaces to avoid warps. I use little balsa blocks underneath to allow fresh air in.

On a small model I then apply two or three coats of very thin dope.... 1 part dope to 3 or 4 parts thinner...again, pinning down until dry. 

For the final colouring it is possible to overlay cut-out coloured tissue trim and markings, using the dope thinner again. Paint can be used, but watch out for weight gain.

This may all sound a bit  'old-fashioned'  but it becomes easier with practice, and it works!

I've still got to learn how to use the modern materials like Litespan and Solartex... now they look very scary!

Regards..... Steve.

[DENNY]

  
    Hi Ben,
         Watch the tail weight (covering with card) as if it comes out tail heavy, you will have to add usless nose weight to get it to fly decent. There is an old saying that I don't remember that well, about a nose heavy aircraft May fly again. A tail heavy aircraft likely won't fly again.
  Keep building.

[Big Bandit]

Hi Ben,

Sorry to hear that you've binned it (I've done the same many times). I was hoping that you would finish it, as I've just pulled this out of the kit store and fancied having a go. Still will and I'll post a build blog when I get started.

Cheers,

Chris.

[Ben Mullins]

Please do Chris! You can carry it on here if you wish, thus threads not doing anything. One thing I did find helpfull was if theres a warp anywhere just put it ontop of some steam and bend it back into shape, marvellous. Another reason I gave up was because of the weight , I couldnt build it light enough and with the electronics in place it would have been far over weight.

[Pat (rActive) Harbord]

Good work, both of you. Ben try another one if you have enough of the parts left you can buy a couple of sheets of balsa and remake the parts using the old ones as a pattern.

I've built both kits, but left them as intended. Weight is always going to be a problem at this scale. You may want to sand the component sheets down on both sides before you remove the parts. You can also carefully drill lightening holes in pretty much every former and rib. PVA is much lighter than CA if used sparingly.I remember the wings of both coming out fairly hefty and very strong, I think you could afford to loose every other rib. You may need to add a stringer near the leading edge to support tissue.

Steve's technique for tissue covering will stand you in good stead, just remember tissue only want;s to go around one curve at a time so you need to cut strips. More coats of 30/70 dope thinners is better than fewer thicker ones.

and lastly (for now) if you are going to rudder/elevator only, a bit of extra dihedral is going to help with stability.

Have fun, even if they don't fly, they are great builds.

[Ben Mullins]

Wish I had kept the parts, but they have been gone for sometime! I might still have the plan though!

[Big Bandit]

Ben,

Before you build any older kit, it's always worth getting a photocopy of the plan and any printed sheets of balsa as patterns. Then you can transfer the balsa patterns onto some new sheet balsa and start again. I normally iron the patterns onto the new balsa if it's an older type copier, or if it's a laser copy after putting the pattern sheet on top the new balsa printed side down, rub acetone through the back of the pattern. Instant transfer ! works every time. I'll do the same before I start building just in case. The last time I did it for this type of model it cost me about £2 for copies.

Cheers,

 Chris.

[Olly P]

Going to try something similar with one of the Cessna kits. However I am moving house this coming week and so will not be starting until then. apparently this can be powered by a .02 'gas' engine, just need to find a stockest. and get all the radio gear!

[Olly P]

Hmm. Have had a thought. in a model of this size, weight is obviosly at a premium. would a co2 motor be lighter? I have never ventured into CO2 before so don't know the weights involved....

[James Marr]

When i was learning how to cover with tissue, i made a practise balsa 'framework' so i didn't wreck a decent model

[Simon Chaddock]

It took me ages to work out how to cover neatly with tissue.

 

The method I finally adopted is to apply a thin bead of wood glue (Evostik Resin W) to the outer edges of the structure, wet the tissue (Modelspan) by just laying it on the surface of the water, shake off the excess water and place it on with the wet side out. The wood glue is thick enough to hold the damp tissue and you have time to carefully remove any wrinkles. Trim and smooth down the edges and pin or weight down until dry.

 

The object is to ensure the tissue shrinkage forces are more or less equal in all directions so as not to distort the structure. When fully dry it can be doped in the normal way.

 

I have found that even very thinned dope can actually shrink too much on really light models. The Triplane in my Avtar was just thinned Humbrol enamel straight on the tissue.

 

An RC conversion of a Kiel Kraft scale rubber kit?

Sounds interesting.  

[Louis Mcnair]

can you plese continu

[Pierre Marais]

I see this thread ran aground - maybe I can revive it for those who was thinking of tackling this project. I converted the 24" Guillows SuperCub 95 Kit#303 with a measure of success. I can post more info & pics when I get home tonight (if anyone is interested)

 

I started the build in March09 as a return to aeromodelling after a break of about 25years. I initially planned to build exactly per plan as a FF rubber powered, but midway through the build I had thoughts along the lines of "I wonder if I could install RC gear and change this into 3-channel RC...)

 

Well, it's now mid-December and I have had many memorable flights with the little Cubbie. I usually fly a TREX helicopter, but find the cubbie accompanying me to the field most times (it's so compact that is easy to transport!)

 

I had much 'fun' recently with it when three crows attacked it in flight and the ensuing dog/crow fight lasted a couple of minutes before the Cubbie eventually managed to shake off the angry mob....

[Pierre Marais]

Something I did not mention in my previous post is that the Cubbie suffered two crashes that required repairs - both were due to pilot error! During each repair I made improvements and this has resulted in the current MKIII being quite robust & still a nice flier (some may consider it overweight, but I find the extra weight beneficial in terms of flying outdoors in a breeze).

 

Let's start at the beginning:

 

Mark I (Start build 01/03/09 - Crash 12/06/09)

 

 

 

I started off building basically according to plan as a FF and then started to incorporate some features to allow future conversion to RC.

 

Changes thus far:

a) main spars extends through the fuselage sides and is joined in the center of the cockpit area. 

b) formers B5 rearwards have cutouts for later addition of R/E pull-pull threads.

c) verticals added both sides between B7 & B8 for guiding future pull-pull threads

d) rudder & elevator split and reinforced to allow for cotton hinges and hardpoints for future control horns.

[Pierre Marais]

e) horizontal stabiliser bottom "struts" added

f) tailwheel made up from balsa and thin piano wire (the skid included in the kit did not look sturdy enough to my liking)

 

More pics:

changes c) & d) 

changes a)

changes e) & f)

 

[Ross Clarkson]

Looking marvelous Pierre.

 

Sorry it didn't work out Ben, keep at it. 

[Pierre Marais]

At this stage during the build I decided to complete the model as a FF and leave the conversion to RC for a later stage. Part of the reason was that my wife&I were heading to Taiwan for my brother's wedding and I wanted to clear the dining room table before our trip!

 

To facilitate future conversion I did not cover the top cockpit area and just used masking tape to hold down the transparent film of the cockpit "glazing". This is what it looked like (next post):