Can you help me with balsa thickness and type for plan build glider ?I

[Paul Jones 1]

Hi guys, we’re attempting to build the Hobby Shack Ridge Runt glider from a plan ( I previously did this one from a kit many years ago ) ....,I have as many details as I can get from it, but there a number of questions re certain bits :-

I’m ordering most of the parts from SLEC, and have most of the order together

 

for all choices in balsa I’ve selected the ‘medium’ grade other than I selected ‘hard for leading and trailing edges of the wings, worth doing or not ?

the fuselage top and bottom appear to be marked 1/16” or 1.5mm, would I assume the sides are also the same thickness ? Seems thin ?

the wing ribs will be from the same 1/16” ?

tail vertical and horizontal (and elevator) seem to be 1/8” or 3.2mm

formers inside the fuz, are these balsa or need to be something stronger ?

the wing has a central spar indicates as hardwood, daft question (sorry) but what hardwood exactly ?

wing dowels, again, what type of wood for these ?

 

thanks for helping out a beginner

 

paul

 

feel free to copy and paste the above, fill in any useful comments if you can help.

I'm certainly sure to be missing some stuff, but hopefully I can end up with everything with one main order, and hopefully one order for ‘missing stuff / replacements

 

Edit, I also obviously need some other aspects, maybe I’ll ring up the model shop tomorrow

 

hinges for control surfaces, think they were just plastic, is there a best type or they’re all about the same ?

need to make the bent bits of wire that takes the servos movement through 90 degrees into the wing for the ailerons, wonder if I can buy this pre-threaded on one end ?

 

need to make the straight link that goes from the servo towards the back of the wing ? Does this stuff have names, if it does I just don’t remember. I don’t have a tap/die set, so again hopefully I can get wire threaded on one end, and bend the other end into the servo ? Any idea on what a sensible gauge of wire would be for this kind of model, it’s a 50” glider with micro servos 

 

 

 

Edited By Paul Jones 1 on 05/05/2020 21:33:07

[kc]

Nobody has answered yet and I have not built the model but maybe somebody who has built it will answer soon.

My opinion is the sides would be 3/32 but it always depends on the density of balsa - very light 1/8 would weigh much the same as medium 3/32 and perhaps do the same job. 1/16 would seem to thin unless very hard balsa. Note grain direction - top is crossgrain 1/16 while fuselage sides would be grain lengthwise.

Hardwood spars are usually spruce.  Dowel is birch dowel ( never balsa for wing dowels ) or simila.  Model usues rubber bands to hold wings, so buy some wing bands from SLEC- must be tight and needs about 6 for safety.   The fuselage side that takes the dowels seems to have some ply in that area - could be 1/32 birch ply  the parts are on the plan nearest the tailplane.  Very important to reinforce around dowels..

You can buy threaded rods from SLEC or Balsa Cabin etc. and matching clevis. Making a Z bend in soft rod is easy or buy special Z bend pliers if you use piano wire. Must be Z bend not simple 90 degree bends unless using SLEC swing in keepers etc.  Otherwise the 90 degrees pulls out in flight!.  If you should need a rod threaded at both ends don't bother with a die the rod probably has a rolled thread which means that increases diameter and it wil be undersize for a die.  You could buy a solder on threaded part from SLEC but a z bend will be fine for this type of model.  So use a threaded rod and z bend the other end ( or simple 90 degree plus swing in keeper.)

First of all have you read all the supplementary sections ( instructions& reviews) on the Outerzone section for this model? Maybe they will help. Ask further questions here as needed - someone will help.

Edited By kc on 06/05/2020 16:29:29

Edited By kc on 06/05/2020 16:39:05

Edited By kc on 06/05/2020 16:44:15

Edited By kc on 06/05/2020 16:49:41

Edited By kc on 06/05/2020 16:57:12

[kc]

Top tip -- next time you buy a kit draw around all the shaped components onto lining paper etc and mark material, thickness and grain direction. The you can replace any component or even make a new model from the data.

[Paul Jones 1]

Wow, thank you so much for the reply, really great advice. I could do with ringing SLEC for advice on the balsa first, the plan shows a lot of sizes but not the thickness of those Fuselage sides nor if it’s hard balsa. I guess if the worst happens and it doesn’t feel right, we just get some more.

We’ll need to template the fuselage sids, tail and wing ribs, it it best just done with tracing paper, then cut out and stuck on balsa for drawing around ?

paul

[dan h]

Hi paul

I use tracing paper or grease proof paper i trace the part then pin the tracing paper to the balsa/ply etc. Then stick a pin around the outside of the lines then sand the rest to get a perfect or near perfect part. Hope that makes sense.

Dan

[Paul Jones 1]

Thanks Dan, I’m learning all the time, cheers for the reply

[kc]

Studying the plan I notice there are 2 dihedral braces which look like 1/8 thick but whether they would be balsa or ply I cannot say. Obviously the grain must be spanwise but the component is the only part not illustrated. Also note that there is 1/16 shear web on the spars out to a certain point on each wing.

All the parts shown together as one sheet would clearly be the same thickness. It seems the formers may be 1/8 and perhaps they are lite ply as the sheet seems too wide for balsa. SLEC sell Lite ply and it cuts easily with a Stanley knife with repeated passes of a new sharp blade.

[John Wagg]

The Runt was a kit and had instructions so the plan would not have to be as detailed if it was a plan only build. Perhaps someone may still have the instructions.?

1/16 does seem a bit thin but the top and bottom are cross grain and it's a narrow fuselage.

The sides have a doubler which is usually thin ply (1/32" or 1/16" but I would have expected a least 1/8" sides.

Wing ribs should be fine at 1/16" but I like to use rib capping strips.to stiffen them. But the ribs would have to be modified to fit cap strips.

I can't see on the plan where it says "hardwood pars" but again hardwood spars are usually spruce. It does show "dihedral braces" and these are normally plywood (1/16". I don't see where it shows how much dihedral though. There are also vertical grain spar webs (1/16" balsa) these add greatly to the stiffness of the wing.

Yes you can threaded aileron rod:-

https://www.ebay.co.uk/itm/RC-Radio-Active-Aileron-Control-Horn-Rod-Set-12G-RCA134/322361379230?hash=item4b0e3c499e:g:BuUAAOSwOtdYUCm-

Hope this helps.

[kc]

Before you finalise your order for balsa check out the SLEC Coyote kit which is very similar and at 49 pounds is pretty cheap and probably not much more than you might spend on balsa and all the linkage parts if you start from scratch. Building from the kit might provide an insight into plan building in future if you note the way they use the thickness and grain.

[Paul Jones 1]

Interesting, I’d seen this Coyote mentioned, it does look very similar.

for the ridge runt, the instructions are easily found online..... but they came with the plan as well. Problem is that even with the instructions there are some details missing, which is the minor problem that I’m having

[kc]

It is amazing how much balsa and especially ply cost now. Add in the cost of the snakes, horns, bands, dowel etc I would be surprised if the bill came to less than the cost of the Coyote kit! SLEC use good parts ( their own mostly ) in their kits so they are good value.

Didn't David Ashby do a review of the Coyote in a recent RCME or is my memory failing?

[Peter Miller]

Well looking at the plan the fuselage sides look like 3/32" with doublers at the front Possibly 1/16 ply as they are shown as thinner than the 1/8" sheet taiplane in the side view.

the 1/16th is mentioned being cross grain on the top and bottom. I would use medium for those.The spars shoud be hard.

You can down load the plan from outerzone where you can also download the original instructions and assorted kit reviews

Edited By Peter Miller on 06/05/2020 18:30:24

[Martin Hodgson]

There is lots of info/threads on www.rcgroups.com and plenty of advice to be had there as well as here.

[Paul Jones 1]

I'm buying the Coyote, I think that's a good move, we'll store the Plan for the Ridge Runt alongside the Minimoa 50" glider that we were reccomended to buy by Leeds Models (you see we like to do things rather backward .... not that you've noticed or anything

we'll get hold of the Coyote, learn about the build and get used to the way they use Balsa, we'll have a much better idea of what's needed for the Ridge Runt which we'll likely do in the future

I'll let you know how we get on anyway

Paul