Slec/Apache Chipmunk kit advice.

[john s]

Hi,

I'm thinking about buying one of these kits, probably the RAF trainer version.

The main question I have is about the two piece wing, I've found some old build threads where people have abandoned the idea due to it being a flimsy and impractical arrangement and just glassed the the wing halves together, as I need it to be two piece can anyone tell me how they find it works for them.

john

[David P Williams]

Been fine for me, although I was also a bit sceptical initially. It's not a model to be thrown around in high G manoevres anyway - lazy graceful aeros like the real thing.

[Tim Flyer]

I will be interested to hear about this too as I bought the RAF trainer version from SLEC last month and it’s my next project after I finish my smaller Slingsby Swallow glider .

[john s]

That's good to read David, I'm pretty well sold on one now just have to decide which version to go for.

I looked at the photos in your collection and particularly liked the elevator trim tab and u/c legs, nice work!

john

[David P Williams]

Thanks John. I had one of the first kits from SLEC so had a few teething problems, but I'm sure you'll be OK. My plan was stretched by nearly 20mm compared to the cut parts - just go with the cut parts and you'll be fine. It flies really nicely, even though mine is heavy because of all the detail I added it still has a very soft stall and lands at walking speed with full flaps. No dramas.

[john s]

That's even better! Its flight handling is praised in almost every build thread I've read and is a big plus for me.

[ASH.]

My Apache Chipmunk has a one piece wing and I can just about shoehorn it in into my saloon car, The fuselage is quite large too but it all fits in okay.

I was just thinking - perhaps when Tim gets his Chippy made,(which shouldn't take too long knowing his build speed) we could all get together for 3 ship (or more) formation flying! It would be spectacular seeing a number of fifth scale Chipmunks all flying together at scale speed. And who knows maybe we could put on a display at W&W's..And have Slec sponsor us

David, what servos' are you using in yours, and what engine?

[David P Williams]

Hi ASH - I think it has Hitec HS325HB in the wings and 5485HB on elevator and rudder. It's a Laser 150 up front - lovely. Only problem was getting the tank height right.

[john s]

I phoned Slec this afternoon to ask a few questions about these kits, and they could not have been more pleasant and helpful.

Found a very informative build thread on RCU well worth a look if if you haven't seen it already

**LINK**

Still humming and harring

Edited By john s on 22/07/2019 17:41:38

[David P Williams]

John - a lot of that thread is quite old, and refers to the old Apache Aviation kit. SLEC did quite a bit of re-design so some of the problems reported have been sorted out on the new kits

[Tim Flyer]

My Chipmunk will have my Laser 180 . I’m sure lots more than needed but as I gave it spare it’s going in . I probably want be able to make a start until later in August though . I used to have the smaller Blackhorse Chipmunk which I loved flying so this is my replacement (upgrade ! )😊

[john s]

Yes I guessed that was the case David but thought it quite good to get the general idea. I feel fine with the kit quality and am no longer concerned with the wing joining method, and it fits my car!!! So the only thing left to do is get the RAF trainer once I open my wallet, always the hard part!

[Applewood]

Posted by David P Williams on 22/07/2019 09:32:34:

Hi ASH - I think it has Hitec HS325HB in the wings and 5485HB on elevator and rudder. It's a Laser 150 up front - lovely. Only problem was getting the tank height right.

Hi David, I’ve read this in a couple of places about trouble getting the fuel tank height right for the laser 150 when inverted. Do you have any lessons you could pass on please? Mine is the raf trainer version, split wing, with laser 150 inverted. Just in the final stages before covering.

Also general question , does the 6mm landing gear wire hold up, or would it benefit from sprung oleos .

kind regards

steve

[David P Williams]

Hi Steve,

I can't remember how I set the tank height initially. I think I set it as low as I easily could, but knew it was slightly high in relation to the Laser carb. First few flights, the engine ran fine on the ground, and for the first few circuits, then it would die back to idle and not throttle up.

After lots of headscratching and communication with Jon at Laser, I carried out some surgery to the front and lowerd the tank as much as I could - about a further 20mm from memory. The engine runs perfectly now and I think the centre line of the tank is pretty much level with the carb spraybar.

I used the top of the landing gear, fitted as plan, but cut off to stubs, with home-brewed oleos clamped to them. They seem to hold up OK, but it flies so nicely down to almost walking speed with flaps that it's easy to do greaser landings (almost) every time.

[BikerDon]

Can anyone tell me what the recommended throws are please as I bought a ready-built one and didn't get the plan or manual (if there is one).

Thanks in advance ?

[Tim Flyer]

The recommendations from the plans are:

Mild:

Ailerons 12mm(1/2”) up and down with expo

Elevators 19mm(3/4”) up and down 

Rudder 75mm(3”) left and right.

 

These rates are similar to what I’m using on my chipmunk now.
It’s a great plane and has seen a lot of flying. Handling is excellent and it’s a real pleasure to fly.

Mine is the new version with two piece wing and a Laser 180. The Laser 150/155 is probably the ideal power plant for this model.  

[BikerDon]

1 hour ago, Tim Flyer said:

The recommendations from the plans are:

Mild:

Ailerons 12mm(1/2”) up and down with expo

Elevators 19mm(3/4”) up and down 

Rudder 75mm(3”) left and right.

 

These rates are similar to what I’m using on my chipmunk now.
It’s a great plane and has seen a lot of flying. Handling is excellent and it’s a real pleasure to fly.

Mine is the new version with two piece wing and a Laser 180. The Laser 150/155 is probably the ideal power plant for this model.  

Brilliant, thanks Tim.

Forgot to include the CoG in my question, what is it please?

Flap throws would useful too.

Ta

Edited April 23, 2022 by BikerDon

[Tim Flyer]

Cof G is marked at 120mm back from front of wing at the centre ( near fuselage) .

Flap movement is not marked. I use around 45-50 degrees as that’s about as far as mine move, I control the flaps using a side slider on the TX so I can adjust travel if necessary. However In practice I always use full flaps for landing and none on takeoff.
The plane’s reaction to flap actuation is minimal and didn’t require a mix as the flaps are relatively small and it’s a very steady flyer.  

[Tim Flyer]

Correction! ….Sorry just double checked my TX to see if I actually did have a flap mix on the Chipmunk and I actually do have a very small bit of down elevator dialled in the flap mix . Obviously you will need to see whether your Chipmunk actually needs it or not . 

[BikerDon]

3 hours ago, Tim Flyer said:

Cof G is marked at 120mm back from front of wing at the centre ( near fuselage) .

Flap movement is not marked. I use around 45-50 degrees as that’s about as far as mine move, I control the flaps using a side slider on the TX so I can adjust travel if necessary. However In practice I always use full flaps for landing and none on takeoff.
The plane’s reaction to flap actuation is minimal and didn’t require a mix as the flaps are relatively small and it’s a very steady flyer.  

Brilliant, thanks Tim.

[BikerDon]

3 hours ago, Tim Flyer said:

Correction! ….Sorry just double checked my TX to see if I actually did have a flap mix on the Chipmunk and I actually do have a very small bit of down elevator dialled in the flap mix . Obviously you will need to see whether your Chipmunk actually needs it or not . 

Brilliant, thanks once again Tim.

[BikerDon]

All ready for the maiden test flight on Tuesday if all goes to plan and the wind dies down ?

[David P Williams]

I have the same two-stage flap settings as the full size - 15deg and 30deg - and they work just fine. No elevator compensation needed as Tim says.

Good luck with the maiden, they do fly nicely.

[Peter Hammond 1]

Hi Don,

 

Very interested in hearing how your maiden goes.  I've read Tims thread and I think a SLEC chippy will be my next build.  Probably the Penzoil.  Just need to complete current projects!

[Andy J]

Well this thread has proved most useful for me as I too have a SLEC Chipmunk about 2 weeks away from its first maiden. Acquired the model about three years ago ready built with an ASP 120 4 stroke but somehow never got round to doing anything with it. So yesterday I recovered it from the back of the garage and dusted the grime off ready for installation of a new receiver.

 

Having no plan or build info was unclear of the CoG position or control throws so will go with the advice on this thread as an initial setting.

 

Need to order a spinner so assume a 75mm will look ok on the model.