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Member postings for dave windymiller

Here is a list of all the postings dave windymiller has made in our forums. Click on a thread name to jump to the thread.

Thread: Super rare Rojair kit - Pre production ME109 with slight fire damage
18/08/2018 21:36:56

 

Making some progress.

I decided to add a better pilot than just the usual head and shoulders so i got one from real model pilots. Had to shrink him in height as i couldnt use the full depth

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Not totally to scale and once the canopy is in plenty good enough. The canopy didnt have any form of frame cast in so i had the bright idea of casting a fibfreglass shell around the outside of the canopy then cutting it out to produce a more realistic frame. Note the whole of the rear of the canopy opens on a 109G

 

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Finished spinner

 

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The thing i love about foam wings is the speed of progress once the wing skin is in place. 2 days work for a nealy finished wing.

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The flaps on a 109 are quite complex with 3 parts. The flap thats about mid span will be lowered by a servo in the wing. I can also make this flap act as an aileron if necessary as the now scalish aileron is quite small. The inner flap has an upper and lower section which is part of the radiator duct and these seperate as the flap lowers. The top will be driven bt a torque arm and the two halves joined by a linkage that increases seperation as it lowers (hopefully!)

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stay tuned

Dave windy Miller

Edited By dave windymiller on 18/08/2018 21:39:09

Thread: Rudder and tail wheel control horn
15/08/2018 13:20:25

Unfortunately I cant show any photos as its hidden inside the fus until its next crash!

Im not sure of the plan its built from but I think its an adapted version of the BH plan. Its 69" span and the fus is in two sections, the rear half is stepped behind the wing and behind the cockpit. Its got 2 X la40s swinging 10x5 3-blade props from master airscrew (about 3 quid each from hobbyking via hongkong!) .

When it all goes well its beautiful in the air. I have the ailerons up a few degrees to prevent tip stalling plus both engines point outwards a few degree to hopefully minimise yaw on a dead engine. Its got no flaps! It did have a clear nose section but since its first crash, its now the fighter solid nose version(never got round to adding cannons). The eagle eyed would spot the wrong canopy for the NF version!

It became a labour of love after 3 rebuilds!  I felt I owed it to Tony Bowler (RIP) who built it.

Edited By dave windymiller on 15/08/2018 13:25:41

13/08/2018 22:27:53

Be warned.

If a tail wheel can cause the rudder arm to slip, 100% it will on the first bump. The mosquito flight will be very short! ask me how i know.

I bought this nice model off the estate of a fellow club member but this one fault has been its downfall (3 times). Each of my improvements proving inadequate.

The grub screw was swapped for a cap head screw but even this didnt give enough grip. Loctte also failed. Mine has now a cap head screw locating onto a flat on the shaft, holding a solid brass arm and has been silver soldered too.

Best solution is independant tail wheel servo which i will try if theres another iteration of this problem!

The mossie now sports an easy to repair night fighter black with home made spinners!

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Edited By dave windymiller on 13/08/2018 22:32:59

Thread: Rudder trim backwards on SG14 (only on one model)
21/06/2018 19:30:17

Thanks for the advice thus far.

Just found the issue. Pressing Sys on the jog dial displayed the transmission protocol ie fasst-mult and not the SYS menu. It was acting the same as pressing the rtn button.

After playing more with the rotary jog switch, the sys button started working properly (dirty or dodgy sensor??)

Now i could get in to this long forgotten menu. i could see rudder was set to reverse in the "H/W set". putting this to normal and reversing it inthe linkage menu sorted it. Obviously i must have done this when i first got the radio as it was "model 1" that had the problem!.

Sys isnt something i normally need to go into and i hadnt missed it at all!

Despite having a degree in computing electronics this tranny still has the power to purplex me.

20/06/2018 21:25:24

Im probably being dumb and missing something simple but my rudder trim operates opposite to the stick on one model (all others are fine). I could cure it by copying another similar model but i would like to know why. Its a model thats not flown for many years so this may be an old problem i never spotted before.

Rudder servo is not reversed, on rx output 4 (FRSKY 8 ch), no mixes and nothing else trying to drive output 4. All rates and endpoints are normal (no negatives) Rudder is J4, trim is T4. Cant see anything that may do this!

Any thoughts?

Thanks

Dave

Thread: Making a spinner by "spinning"
26/05/2018 22:19:13

ME109 had a cannon in the centre. I discuss this earlier in the thread.

26/05/2018 20:41:59

Final push

I attach the prop to the back plate so i can mark off the blade positions. An old crankshaft is useful here.

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Mill out slots to miss the blades (not too wide, enough to clear the blades with say 1-2mm gap.  This can be done on a lathe quite easily!

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Once the prop fits the back plate, cut out the spinner to miss the blades with a small gap. I find an old prop with one blade handy here. Once the cutout shape is good trace it and use the shape for the other cutout(s).

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Note the cut out has to be big enough (underneath the blade) to allow the spinner to fit without angling it.

Once the backplate, prop & spinner all fit together, i make a reference mark on both backplate and spinner so these always align.

To fit the screws I drill through both components with the tapping size. Im using m2x5mm CS screws four of between each blade. Drill at the right angle so the screw head is flush to the spinner. I have used an m4 rod to hold the parts tightly together, we dont want them moving.

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Open up the holes in the spinner to clearance holes and countersink to suit the screws.

The end result! If made accurately, it shouldnt need balancing!

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Im sure there are other more scales ways of attaching the spinner rather than screws but this works well and can withstand a starter motor no problems.

I have never found a need to add grips/nurling to stop the prop rotating on the back plate on a 2 stroke. A 4 stroke may be different.  Just keep an eye to make sure things stay aligned and check the screws stay tight. A mild thread lock may be necessary on the screws if they undo although i have never found this.

 

I wouldnt bother with all this for a sports plane, its so much easier buying a spinner. For non-available spinner shapes for scale planes it certainly works if you have the patience and is rewarding to do.

Fee free to post any pics of spinners you make on here!

Now back to finishing off the ME109

Dave (Windy) Miller

 

Edited By dave windymiller on 26/05/2018 21:03:32

22/05/2018 17:33:24

The cyno is enough as long as there is enough area. My 3" spinner was held perfectly well by a 2" dia face taking a maximum of 20 thou (0.5mm) off each cut. Dont let the parts get too hot.

I used a very thin cyno and made sure the parts were well forced together as it set.

Cheers

Dave

21/05/2018 23:07:45

Hi Danny

The metals are nothing fancy. Dural (duralumin) is simply a tougher grade of ally but normal ally should suffice and would be lighter. I had dural kicking about as it was once part of a wheely bar from a drag bike. The metal for spinning is just bog standard 1/16 ally sheet (dont know what grade).

I have made spinners using glass cloth (having made a mould from a vac formed version) but with the same back plate idea. Heres my mossi. These spinners withstood a vertical crash into the soft field after the usual tip stall that mossies love to do so much. Thankfully, the repairs to the plane only took a week.

Dave

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Edited By dave windymiller on 21/05/2018 23:09:37

Edited By dave windymiller on 21/05/2018 23:11:42

20/05/2018 22:45:28

To make the backplate

True up a rough cut peice of 6mm dural using a 6mm hole and 6mm screw to hold it in the lathe. Once round it can be removed and a better, more accurate method of holding it will be used.

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Put a peice of scrap thats smaller than the spinner into the lathe and true up the front face and add a shallow 8mm hole

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After degreasing, attach the backplate to the newly formed face using thin cyno and a tailstock centre to get it reasonably true. The faces should be very true if alls well and the o/d can be also trued up. Dont remove this from the chuck until all machining is done.

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Set the tool stock to an angle that suits the spinner at the base.

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Machine away the o/d until the spinner fits over the backplate. Leave a 1.5mm shoulder for the spinner to seat on.

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Take off just enough for the spinner to seat against the 1.5mm shoulder. It should sit nicely and be a tight fit that holds itself on. All being well, the spinner will spin true!  The shoulder edge can be trimmed to match the spinner either using the same angle or at 90 degrees as preferred.

Machine away the centre to leave a 1.5mm backplate and a 3mm thick outer ring where the spinner fits. Also open up the centre with a boring bar from 6mm to fit the engine (1/4" in my case).

20180520_213934.jpg

It can now be removed from the lathe by heating with a blowtorch until the cyno fails. Clean up the back of any cyno that remains.

 

Final instalment soon!

Edited By dave windymiller on 20/05/2018 22:54:45

23/04/2018 22:26:47

Again thanks for the complements and good luck with the albatros spinner. I guess this is posted in the right place already if rcm&e wanted to do an article and i would oblige if asked even if i am just a garage bodger type chap with improvised equipment.

I will finish the spinner article soon, just got back from a walking holiday so i cant walk now!!

13/04/2018 20:30:00

thanks for the complementry replys folks. Bit side tracked at the moment with holidays and work so will do the last bit in about 2 weeks!

Dave

Thread: Dangers of methanol
11/04/2018 22:35:50

If the safety of flying is expressed in terms of death per mile travelled, a trip to mars using the same figures will result in only 2 out of every 3 trips getting there.

Dont know if the above is true as i cant be bothered to research it but when i heard this it made me smile how statisitics can be manipulated. Flying is so dammed dangerous.

Thread: Making a spinner by "spinning"
04/04/2018 20:02:35

Rotation speed. Ive read it should be 800 rpm for initial roughing and 300 rpm for finishing. I use a lot slower speeds and it seems fine as my lathe lacks power at higher rpm.

If you have judged the size of the disk correctly, there would be nothing left as you cover the mandrel. If its too big you will end up with some excess that can be cut off with a lathe tool. Hopefully the spinning is longer in length than the final spinner so it is a simple case of trimming the excess and making a neat edge.

imag0236[1].jpg

You can also remove the concave washer and neaten up the centre if necessary as the metal should now be a tight fit on the mandrel. You can also spin the metal over the back edge of the mandrel so it becomes permanently attached allowing you to give the centre more work with the tool if required. Once done part off the spinner to allow it to be removed from the mandrel.

If you managed to spin a sufficiently thick layer onto the mandrel, there should be enough material to allow any scratches to be polished or even machined out!

imag0235[1].jpg

Final section – making the backplate and attaching the spinner.

04/04/2018 20:02:17

The first task is to cut a blank disk of ally about 50-70% bigger than the finished spinner. Try to make the blank reasonably round and smooth as jagged edges can act as a focal point for the metal to crease. I used 1.5mm or 1/16 inch thick ally.
Next task is to anneal the ally. This has to be done several times during spinning. I just do it till it looks hot enough but you can use soap as a temp indicator (when it turns brown when its done apparently).

The blank has to be attached to the mandrel. For my turbine, all the parts I made didn’t use the centre so I could easily drill and screw the blank to the mandrel. The ME109 has a hole for a cannon in the centre so I also used a single m4 screw to attach the disk. To spread the load I made a 20-mm washer with an inside concave shape that matches the centre of the spinner.

If you don’t want a hole in the centre, the usual way is to use a live centre from the tail stock to physically push the disk/ concave washer against the chuck. Unfortunately my lathe isn’t able to do this as the headstock uses a taper plain bearing and any excess load from the tailstock causes it to sieze! Good job it’s an ME109 spinner with a hole I’m making.

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The tool I use for forming is a brass rod approx. 12mm dia and some 600mm long with a file handle at the end. You could attach a small piece of brass to a steel rod of course. Cut the end of the tool at an angle, round all edges and polish it smooth. You can also use ball races with a radius ground on one edge mounted in the toolstock or on the manual tool. This is better for stainless ive found but for ally I prefer the brass rod method. This is used with a lubricant to keep the brass and ally from knarling together. Motorcycle chain lube works for me but candle wax or tallow can be used.

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To lever the tool against the ally I use a bar mounted on the tool stock with holes in for a peg to sit in. This can easily be altered to get good leverage.
The tool is used against the ally UNDERNEATH the chuck. This way if you were to catch the chuck it wouldn’t fire the tool towards you. I must stress here that spinning probably breaks all the rules you are given for using a lathe safely!!!

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When spinning, there are two different approaches. If you force the ally around the mandrel whilst keeping the ally disk flat/radial, you are in effect pressing the mandrel through the ally and extruding it. This thins the ally much like pushing your finger through taut rubber sheet. Any section that’s parallel will get too thin and probably sheer off. This pic shows this effect.

The other way is to “lay” the ally onto the mandrel by forming it into a cone (similar to the drawing at the top of the 1st posting) and done by sweeping strokes towards the outside of the disc. Unfortunately, if you wrap a sheet of paper around the mandrel it will wrinkle and crease which we don’t want. Spinning is therefore a mixture of the two methods above. We want to lay it down to keep thickness but have to extrude it enough to keep it from wrinkling. You are in effect moving the metal about like clay on a potters wheel!

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The first version of the spinner I made, I extruded it too much and ended up with a spinner 0.6mm thick (too thin). My next attempt resulted in a 1.6mm thick spinner, much better!

During the making of my second spinner, the ally started to wrinkle which first shows as a judder felt through the tool. Don’t try to get rid of it by carrying on, it rarely works. It’s a good time to take it off and try to minimise the wrinkles with a hammer. It doesn’t have to be perfect, just remove the worst of it and re-anneal. The wrinkles are then removed by concentrating the force at the mandrel to extrude, ie push the cone further to the left. This action should cause the cone to open up and the wrinkles disappear (or it ends up a knackered mess ready for the bin!)

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Its very difficult to put this whole process into words you just have to try it and spot the various behaviours for yourself.

 

Edited By dave windymiller on 04/04/2018 20:23:14

31/03/2018 13:29:22

Thanks

Yes it was in steps. I used a cad program with the image of the spinner imported and then manually worked out the dimensions in 0.1mm steps to get a list of X/Y dimensions.

Thread: Super rare Rojair kit - Pre production ME109 with slight fire damage
31/03/2018 13:15:27
Posted by David P Williams on 31/03/2018 10:33:22:

Well I have a lathe and an interest in spinning spinners! Any chance of a 'how to do it' thread Dave?

No problem. Look here I will chart the progress on making another spinner (wasnt totally happy with the one i made)

Cheers

Thread: Making a spinner by "spinning"
31/03/2018 12:52:32

In another thread, i mentioned i made an ME109 spinner from aluminium by using a method called "spinning".  In response to a "how to do it" plea, please see below.  I must firstly stress I am no expert and my methods / equipment are probably laughable to an expert however it does show good results can be obtained easily with just a normal lathe.

Spinning in a nutshell

I built a jet engine several years back and these are some of the parts i used 

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Some of the spun components are part of the combustion chamber and made from inconel sheet which was a nightmare to spin.  Some of the mandrels for this are in the forground.  The alluminium intake is a hellishly complex shape requiring a split mandrel so it could be removed. It turned out to be a breeze to make and the final intake was made in one attempt (unlike the inconel bits!). The mandrel took weeks to make and the final spinning about 2 hours for the ready to run component!

The mandrel can be made from metal, bakolite or even hardwood.  Aparrently you can make a wood version, spin a layer of aluminium over it so the woodgrain that may show through can be polished off leaving you with a mandril as good as solid metal (not tried it however).

For the spinner i made i used 12mm bakolite in layers attached to a chunk of steel for gripping in the lathe chuck

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More to follow!

 

 

 

Edited By dave windymiller on 31/03/2018 13:21:20

Edited By dave windymiller on 31/03/2018 13:22:23

Thread: Super rare Rojair kit - Pre production ME109 with slight fire damage
31/03/2018 10:28:01

Thanks chaps. I learnt spinning by making a gas turbine! After spining stainless bits, ally is easy and anyone with a lathe could do it, even with a toy lathe like mine!

30/03/2018 21:37:38

As you cant get spinners the right shape i decided to make one using spun aluminium. The chuck was made from layers of bakolite. I may yet decide to make a glass cloth version using the chuck to make a mold.  The backplate is cut for a 10X5 3-blade prop 

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The foam blank has been modified to take an electric retract. I will need to modify the retract to limits its travel to about 80-85 degrees.  

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Windy

 

Edited By dave windymiller on 30/03/2018 21:41:19

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