Jump to content

DB Cirrus Moth build


Recommended Posts

Same at my local college Dwain, I used to go in there, they had every conceivable machine, with a 6 foot bed vacuum former, and an 8 foot press for making such things as plywood or any chosen laminate !

My favourite " borrow " at the time, at a cost of a packet of chocolate biscuits, was time on the vertical miller

All gone now, all sold off for " progress"

Link to comment
Share on other sites

Posted by fly-navy on 02/03/2017 22:10:47:

Bored my way through "They flew alone" on iplayer earlier Steve, plenty of Moths on there.

Have you thought of modelling your plane on Amy's as a tribute to hercool

Good news about the sunny weather today give you a chance to dry out a bit, bad news got to chuck it down tomorrow. Coming along nicely mate.

That is a surprisingly boring film. I watched it on the iPlayer a while back. It makes you appreciate how film techniques have improved since it was made.

I think if I was going to model a famous Cirrus/Gypsy Moth it would Francis Chichester's. His first Gypsy Moth was the aircraft he successfully navigated across the Tasman Sea with a vital refuelling stop on Lord Howe island. Gypsy Moth IV was the yacht in which he sailed single handed non-stop rund the world in the days before GPS and he relied on 'proper' navigational skills using maths, paper charts and a sextant. Both huge achievements.

Dwain:  Certainly make sure you have plenty of right thrust built in.  I had none in my Tiggie because there's none shown on the drawing.  I found that I couldn't manage stall turns to the right because I'd already used up all the rudder movement to keep the model vertical on the climb so there was none left to turn right at the top. 

I've since put a bit in but not enough because the offset makes the prop shaft foul the cowl.  Normally I offset the motor mount to bring the prop into the middle of the cowl.

Robi

Edited By Geoff Sleath on 03/03/2017 11:21:28

Link to comment
Share on other sites

Hee Hee... You some how linked up to the picture in your quote john,,,,laugh

I added some 1/16th ply to the back of the motor mount and sanded it all square on the belt sander.

I made allowance for building in side thrust, plan says 2 deg I can add 4 if I need it.

A bit of furkling and its all lined up, I took some balsa out of the front formers to get the motor central and further forward so the prop can go round.

D.D.

img_20170303_211242.jpg

img_20170303_211255.jpg

img_20170303_211346.jpg

img_20170303_211058.jpg

img_20170303_211044.jpg

Link to comment
Share on other sites

Posted by Dwain Dibley. on 03/03/2017 21:59:53:

I made allowance for building in side thrust, plan says 2 deg I can add 4 if I need it.

A bit of furkling and its all lined up, I took some balsa out of the front formers to get the motor central and further forward so the prop can go round.

D.D.

Hopefully that side thrust will be sufficient and I've found that it's always a good idea for the prop to go round cheeky

Neat motor mount. Will you arrange for it to be twisted slightly to adjust side thrust or will you do it the crude way (like me) with washers? There's plenty of space for abit of ballast, too if it's needed. I'll be very interested to see how it balances.

Geoff

Link to comment
Share on other sites

Good Evening Geoff,

I will fix the mount in at 4 deg and then take out the side thrust with washers/wedges, if needed.

Mind you I could make it adjustable with some simple brackets.....good thinking Geoff.. wink

The motor was fatter than the existing opening at the front, which was made for a four stroke's prop driver.

Yes there is quite a bit of room in the front to slide in some lead....or a receiver battery..

D.D.

Link to comment
Share on other sites

Percy:

If you look at the picture of my Moth on this thread (on the previous page, I think), you'll see that I have cut a hatch in the top of the fibre glass cowl and the battery goes in there at an angle back into the fuel tank area. It takes a 4S 4AH pack but it needs to be a short one and none at HK will fit because of length. They have discontinued the short fat ones which were (are) ideal for me.

I think Dwain is going for a 3S LiPo but I much prefer the 4S option with lower current (20 amps in cruise) and that's what will be the energy source for my DB Cirrus Moth when I build it in the near future.

Very much agree with your suggestion for separate aileron servos rather than bell cranks. There are so many inexpensive metal geared ball bearing mini servos with more than adequate torque ratings available now it's not worth the faff of bell cranks. I'm using Airtek Kpower MO200s in mine.

This build is inspirational for me and I'm sure I'll be referring to it often once I get started on my own.

Geoff

Link to comment
Share on other sites

Hi Percy,

The lipo will be velcroed behind former 2, or in front depending on Balance, I don't seem to be able to uplad pics at the moment, but will do later.

The 4 max set up is for 3s but I have 4s lipos about the place if needed.

I left the bearers in purely for their weight , of course they do beef up the front also, and I have used them to build my motor mount on.

You will not be disappointed with the quality of the kit, both wood and fit are excellent.

D.D.

Link to comment
Share on other sites

OK. For some reason my last batch of pics were all about 12MB, and wouldn't upload. ???

Unfortunately I couldn't repeat some of them, but here are the ones i could.

D.D.

First off , I found this in my boxes of bits and thought it will be an easy to make solution for a catch.

But it fouled on the lipo so a no go. The solution can be seen in the same pic....back to basics but fool proof.

img_20170304_204242.jpg

The catch and the hole I made for the red one, that I had to fill in with scrap.

img_20170304_203655.jpg

Here you can see the screws I inserted to catch the magnets in the hatch. They were C/A'd in and then filed flat with the ply.

img_20170304_140119.jpg

The magnets. I drilled holes slightly under size, so the magnets have to be pressed in, use any flat item, I use the end of a bigger drill bit. Before that, I put the hatch in place and mark the positions for the screws by pushing a sharpened ex allen driver through the center of the magnet holes, having found the centers from the underside first ( one of the pics that I cant replicate ) the magnets are rare earth type.

img_20170304_140724.jpg

The hatch in place nice and neat. The magnets would probably hold this on their own, but I added the catch to save me loosing all my hard work in a field .. wink

img_20170304_141204.jpg

The battery position, and for Geoff, there is a 4s 3000Mah battery in reserve...cheekywink

However , to fit this I will have turn it thru 90 deg or file some wood out of the bearers.

img_20170304_204056.jpg

Link to comment
Share on other sites

Those magnets are difficult to handle! Turn your back for a second and they've jumped to join their friends ... or any piece of steel in the near vicinity - they're quite fickle!. I use a piece of 6mm dowel to push them in; they aren't so friendly with wood

Geoff

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...