Mirage 3 project-EDF version

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Theuns v V
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Re: Mirage 3 project-testflight soon

Unread post by Theuns v V » Thu Jul 25, 2019 6:30 am

I have decided that I will make another airframe with some of the weight saving ideas I have but this time I will sort out the 105mm EDF to get the "advertized" 5-6kg static thrust before I do the final instelation. I think the new shape intake ducts will help allot.

It will run on 2 by 22V 5000 pluss lipos.

It wll be interesting to compare the edf setup (i think it may be lighter) to the turbine one once it gets flying.

Granted the edf will neve sound and smell as cool but the simplicity of operation makes it rather tempting ...

I will not bore you with another build, maybe just show the new internals and some of the weight saving ideas.

T
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Re: Mirage 3 project-testflight soon

Unread post by Shaunruth » Mon Oct 07, 2019 8:59 am

Hi. How did this project go? I’m looking at getting another Mirage EDF.

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Re: Mirage 3 project-testflight soon

Unread post by Theuns v V » Mon Oct 07, 2019 10:31 am

Hi. I will.pm you.shortly. I have been waiting.for.owner to collect.the repaired mirage for.turbine testflights,.and I got an contact.now.for.nice.retracts,brakes door.sequencer and it.will be built.arround.my 12 blade 105 EDF but a high performance 90/mm should also work well if.u.can.get.close to 5kg thrust or.more.
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Re: Mirage 3 project-testflight soon

Unread post by Theuns v V » Tue Oct 08, 2019 7:49 pm

I got materials today for the dedicated EDF version of the Mirage project. This has to be lighter than the turbne one and I will have to basicalle build it arround the whole edf setup.

For a turbune the setup is allot aeries since the engine is not really affected so much buy the airflow, wherever there is a hole the turbine will suck it in....on the EDF the intake, edf and outlet needs to be done very acurately with smooth laminar airflowinto the fan face.

It takes up a lot of real estate insode the fuselage and it becomes cramped vert quickly :shock: , 2 by 6 cell 5000 packs also takes up space so carefull thought will be needed.

I want to make a complete intake and outlet setup and test it on the bench to see where I need to refine a little but I did alter the desicn of the intakes to give a nicer ,smooth flow. Now the ratios of diameters to fan area and reduction in the outlet to get a good enough static thrust for takeoff VS dynamic thrust for speed flight comes into play.

I am also going to modify my molds to incluse a joggle joint for the wing LE and fuselage seams, its lighter, simpler to join and stronger.

Hopoing to get started this weekend if the WX holds.

T
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Re: Mirage 3 project-testflight soon

Unread post by blender » Tue Oct 08, 2019 8:29 pm

Theuns v V wrote:
Mon Oct 07, 2019 10:31 am
Hi. I will.pm you.shortly. I have been waiting.for.owner to collect.the repaired mirage for.turbine testflights,.and I got an contact.now.for.nice.retracts,brakes door.sequencer and it.will be built.arround.my 12 blade 105 EDF but a high performance 90/mm should also work well if.u.can.get.close to 5kg thrust or.more.
Hi T

I got >4kg static thrust with an 8s Wemotec 90mm Midifan Evo so 5kg should be very attainable with a high performance 90mm 12s setup. I'm keeping a beady eye on your project :wink: .
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Re: Mirage 3 project-EDF version

Unread post by Theuns v V » Wed Oct 09, 2019 6:28 am

Howzit Mr B . Yes I am quite confident a high performance 90 will work.
One will just have to alter the diameter of the back of the intakes. Lucky my intake molds are quite easy to modify.
I am working om shedding some weight by substetuting ply mounds for UC and spruce spars with lite ply that is skinned with carbon and other little things aswell. If I could get the model to be 7kg all up ready to fly with 1.8 kg of Lipos I think it will be a winner.

I looked at several of the "avanti" tipe jets that are powered by 10 pluss Kg turbines that weigh arround the 13 kg mark and they have about the same wing area as I have on the Mirage, but my aerfoil is allot thicker and should fly well on even 8 kg or so with a light wingloading.

Remember the initial ICDF "flew" on 3,4 kg and weighed in eccess of 7.2 kg and the wheels couldnt retract causing loads of drag.

What iIwant to acheive with this build is a model that can fly fast enough to look scale but still be stable and predictable at low speed to cater for okes like me that are not so "fast" to keep up with these ultra fast stuff. Besides the fast aeries eat up sky so fast you can hardly fly straight before you need to turn again.

Also transport must be easy for a small car like my Kia, must be a simple to operate and cheap to maintain model. The nice part is that if I clip a wing or something I can just mold another instead having to dump the whole model in the trash :lol:


I have also chatted to Down and locked to install their 60 size electric retracts with 5mm wheels and electric brakes as the place where I fly we need to stop fairly quickly and I didnt want to mess arround with air retracts and air brakes. I want to flip a switch to stow the gear and only think of it again when I need to land :wink:

On the P-51 tooling I have learned allot of little tricks to make the molding easier. This weekend I want to make seperate molds for the Mirage's wing and tail . These bolt onto the main molds and will form a joggle joint when I vacuum the wing skins in the molds. Then when I join the top and bottom skins I simply put glue on the joggle and press the two skins onto the internal structure. The joggle on the leading edge then is very strong, easy to do and doesnt split open like some ARF kits, an open LE can lead to inflight failure !

I am quite exited to start this EDF version and hopefully the Turbine version will also fly by year end. [-o< Will be an interesting comparason
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Re: Mirage 3 project-EDF version

Unread post by Theuns v V » Mon Oct 14, 2019 6:34 am

The repaired turbine airframe was xollected this weekend and should be ready to go soon.
In the meantime I have made seperate bolt on joggle molds for the wing LE and will do the same for the fuse molds.
As you can see when a skin is then bagged into the mold, it makes an extra little 12mm high "offset lip" that acts as a backing for the other half of the skin to glue onto to.
This will work allot better than the balsa strip I had to carve and glue into the wing LE and the glass joiner strips I use for the fuselage.

This way I should also not get the hairline (or sometimes dangerous big) cracks one sometimes find on kits where the joint starts to open up.

The plan was to make wingskins yesterday but allas I forgot to buy bagging plastic so it will stand over till next weekend. #-o

I will also make a full length intale and thrust trunking and bench test this before I install in the fuselage to see if any tewaking is required.
The nice thing with the way I did the intake molds for EDF is that I can make a seperate intermediate duckt that joins my standard intake used on turbines to a 105mm or 90mm EDF , maybe even a 120mm :)

T
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Re: Mirage 3 project-EDF version

Unread post by Theuns v V » Fri Oct 18, 2019 8:21 am

I have waxed and prepped the wing molds for a set of wingskins this weekend if the powercuts are over...

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Re: Mirage 3 project-EDF version

Unread post by Theuns v V » Fri Oct 18, 2019 5:11 pm

I have changed from using wood spars to a full composite spar. The caps will be uni carbon strips molded into the wingskins,the shearweb will be made from aerex foam cladded with 45 degree glass and 90deg carbon. Should be lighter and allot stiffer than wood spar.

T
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Re: Mirage 3 project-EDF version

Unread post by Theuns v V » Sat Oct 19, 2019 6:48 am

with impending loadshedding the whole weekend I might not get to bag the skins, atleast the molds have been primed and ready to go. I will look into making up spar materials and the intakes in the meantime.

The wing only takes 200 gr of primer to give it a good coat insode the molds. To have to try prime,fill/sand the raw glass readt for paint is a heap of work and weight will be much higher.
Hopefully if my prep was OK I will have only joint seams to fill.
T
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Re: Mirage 3 project-EDF version

Unread post by Theuns v V » Sun Oct 20, 2019 2:26 pm

I made the shearweb mterials and sofar it looks good. a Sheet of 3mm by 150mm by 600mm weighs 235 gr but allot stiffer than ply or spruce. Rib materials is a sandwich of 163 glass either side of aerex. Sheet of 3oo mm by 700mm is 195 gr. Feels same as lite ply of 3mm.

The bottom wing went into the bag at 0700 this morning and the saturation through the glass /carbon looks good.
Top skin is in the molds now.

Will weigh the skins tomorrow but I estimate about 400 gr per skin.

T
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Re: Mirage 3 project-EDF version

Unread post by Theuns v V » Mon Oct 21, 2019 6:50 am

I demolded now anr am pleased with the results, overall nice and smooth with crisp pannel detail. Just a light "flatting" and should be ready for paint so no real weight will be added with primer other than the joint seams that will need filling and sanding.
The undercart will be from down and locked but most sets that can handle a 7-8 kg plane should work. Wheels will be 76mm with electric brakes.

The joggle looks like it will work nicely and give a light yet strong leading edge bond.

I think the top sking will be about 480 gr and bottom maybe about 440 gr, not to bad for suce a large surface area. I cant see it gettin much lighter without me having to mold it weaker and risking failure.

The geardoors and servo hatch reccess has come out well, and will make for a nice seal when retracted

T
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Re: Mirage 3 project-EDF version

Unread post by extra300s » Mon Oct 21, 2019 7:09 am

Dit lyk baie goed!
Futaba!!!!
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Re: Mirage 3 project-EDF version

Unread post by Theuns v V » Tue Oct 22, 2019 6:49 am

Dankie.

Bo skin 580 gr, detail kom mooi uit.
Vorige vlerk was 2,05kg, hoop om die een 1.8 kg te kry

T
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Re: Mirage 3 project-EDF version

Unread post by extra300s » Fri Oct 25, 2019 11:42 am

Wanneer vlieg jy nou die turbine version Gideon?
Futaba!!!!

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