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Valdez Stol Record breaker build blog


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  • 3 weeks later...

Hi Daniel.

SLEC can provide balsa dowels. but you could use 1/4" sq if you wanted. 1/4 sq. would actually be harder which would be better as I found that the specified "hard" balsa dowels were not as hard as I would like.

In fact you could use ordinary 1/4" dowels (Or 6 mm) as I found that the CG was actually further foward than I had expected using a 2200Mah 3 cell battery.

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Hi Pete

Yes i know Slec has a wide selection of material but problem is since I’m from Malta its really a pain getting stuff here with the postage costs, hence why i have to improvise when building from plans. For example in this case, in order to build the fuselage i was already thinking to use 1/8th poplar ply instead of 3/32 balsa and 1/32 ply. Not because of balsa sheets right now i have plenty but 1/32 ply its a pain to get it. 1/8th lightply on the other hand i can get it easy.

kind regards

daniel

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Hi Daniel

Yes, that should be fine. I would suggest getting a 1/4" diameter round file as you will need to make grooves in the ply to take the dowels. You could cut them down where they go over the ply but I woud suggest making the transition from round to half round over an inch or so to avoid a sudden change in section which is always a weak .spot

Hi Fly boy.

The model uses a total of 6 9 gram metal geared servos. All from Hobbyking.

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Just realised that while I had put the model on the "New Models thread I haven't put it here.

Well I can tell you that the model flies like a dream, IT is rock solid in flight so one can concntrate of actual positioning rather than flyimg.

It is also highly controlable but very positive. It is NOT atall aerobatic.

I was able to fly for the camera in a very small area doing tihhty turns etc close to the ground without any worries.

I did not get it to stall or spin.

I now have to learn to do those ultra short takeoffs and alandings

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Posted by Peter Miller on 02/03/2019 08:23:13:

Just realised that while I had put the model on the "New Models thread I haven't put it here.

Well I can tell you that the model flies like a dream, IT is rock solid in flight so one can concntrate of actual positioning rather than flyimg.

Now there's a surprise!!!

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  • 3 weeks later...

Peter

Absolutely on my build list so looking forward to the magazine. When you know which issue, will you let us know.

Another one of your quirky designs you like so much.

If I can take off and land on my balcony I will be well chuffed wink

Levanter

Edited By Levanter on 20/03/2019 13:45:43

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  • 3 weeks later...

This will be a summarised build blog of Frank Knapps Li’l cub.

This will be the free plan in June’s RCM&E. Just to wet the appetite of aspiring builders, Peter had kindly sent me a copy of his original hand drawings, sketches and some build notes, and will be using those as a basis for the No 2 protoytype build.

The plan is for an electric powered 55in span model around 1:6.5 scale and 3 Lbs AUW. It’s and all wood build.

The Knapp original is a heavily modded Cub J3, stripped to bare essentials, lots of carbon fibre , new STOL wing with flaps and leading edge slats. In 2017 the aircraft set a new STOL world record at Valdez, with a take off in 13 feet 8 inches, and a landing in 10 feet 5 inches. A reputed top speed of 62mph with its large low pitch prop to maximise take off thrust.

I have made a few minor changes to the original that will hopefully work out and add a touch more scale fidelity. I will detail these in the build blog.

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I made a start with the tail, elevators, rudder and fin. The tail has a 1/4 in balsa spar and laminated outlines from 3 x 1/16 balsa strips. I made the laminate mould from 6 mm depron. The balsa was soaked in my custom soaker, a length of old waste pipe sealed at the bottom with aluminium duct tape, fill with hot water, pop in the balsa, bung the end with a piece of foam, and 10 mins later you have pliable balsa ready for bending, I used Titebond and held the laminates in place with masking tape.

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I have opted to use polyspan (polyester tissue) for the covering. This is iron on using Balsaloc ( or In my case Impex Pva, which is in the gold bottles from any haberdashery or Hobbycraft store). It shrinks on like solarfilm, heat takes out the wrinkles, shrinks round corners really well, then 2 coats of dope to seal it. I have airbrushed Dulux tester pot yellow, mixed to Lockhaven yellow, the True cub yellow colour, the rudder has 2 coats on it probably needs a another coat

 

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Edited By Tim C on 09/04/2019 14:30:56

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I have opted for polyspan as the covering medium, for those not familiar, this is a polyester tissue, it’s lightweight, strong for it weight, but the strength is a bit unidirectional, in that it tears more easily on one direction than the other. It heat shrinks but needs a separate heat sensitive adhesive. I used Impex original hi tack all purpose glue, available from most haberdashers, it used by sewing and garment makers.

Polyspan is applied glossyside up, the adhesive I thin very slightly, maybe mines thickened, as the bottle is over 4 years old! Brushing on a coating on the balsa surfaces and letting it dry, lay over the polyspan tacking down and pulling it tight, I use a slightly hotter iron than with regular covering circa 130c, once it’s covered, I ramp up the temp to 170c and shrink and seal up the edges. Repeat the adhesive on the reverse side and brush a coating on the overlap edges and repeat again,

What you end up with is a nice wrinkle free taught covering. Next off I used a coat of shrinking dope to seal the surface, but WBPU seems to work as well, though needs an additional cote. Already for top coat colour cote.

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