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STOL Zenith ch750


Martian
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750-side.jpg

Here is what I propose to build ala mass build STOL

60" wingspan full span fixed slats full span flaperons (junkers style) they will be hinged to be in free air below wing trailing edge ,hopefully the servos will be within fuselage,wing will feature a deep chord and flat bottom,all flying aero fin no seperate rudder and upside down tailplane with roughly 50% elevator area oh and it will be leccy powered 4s lipo not decided on motor yet .build will depend on available funds

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  • 3 weeks later...

Hi Martyn not to well really I managed to get a chest infection since last posting and have been waking /sleeping for last two weeks getting over it now ,I have tried applying myself to some of the problems I need to overcome and made some templates will take pics and post an update in next couple of days

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  • 1 month later...

It's been a slow start but I have managed to build 2 wing halves and made a start on 1 slat

below drawing of tail section showing tail formers of 1/64th ply and balsa and a fibre glass sheet insert for the hinge surface,also the L shaped pieces are for the Junkers style flap or in this case flaperon they are made from a laminate of UVPC and 1/64th ply these are mounted in the wing at the trailing edge using a sandwich bond they form part of the flaperon hinge . Also you can see some of the wing ribs using a NACA 65019 profile .

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top view of fuselage outline

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side view fuselage and my feet on a chair

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cross section of I beam spar which is 1/16th balsa and depron laminate this is my test spar it turned out really strong.

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more later

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a few more pics to bring it up to date

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wing root,still undecided on how to join wing to centre section that will be fixed in place on top of cabin which in itself has a lot of glazing and I may have to make a brass tube support any way more thinking to do bottom sheet of wing is not in place yet until joining method is decided.

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start on first slat it's fully built up and will be very light

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  • 2 weeks later...

Slow going but more progress

underside of slat showing formers some of the formers 4 to be exact are doubled this is to provide pockets for the acetate supports

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Slat underside now planked visible is one of the pockets for the acetate support

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wing leading edge test piece to work out position of slat support

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Slat against the wing leading edge

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This image shows approx gap of wing leading edge and back of slat

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slowly building up a kit of parts ,below is 1 elevator and tailplane half plus wing half and flaperon

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another view of same parts

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slat in place for the pic also flaperon place under trailing edge it will be supported by hanging hinges just like a Junkers flap

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flaperon profile

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  • 4 weeks later...

For anyone interested here is my latest updates, still intend to finish for Greenacres

I'm building the fuselage in three sections below the rear section into the cave ,I,m using lightweight snakes in a pull pull layout elevator controls will be hidden as per full size and again as full size the rudder controls will be visible

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tailplane and elevator (ignore the purple hue it's as a result of an attempt to use tissue) you can see the elevator hinges are hidden they consist of brass tube built in and a piano wire pin runs right through the connecting points are from glass fibre board as are the control horns.

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this pic shows how the tailplane is mounted about 4mm above the fuselage top supported by 1/32 ply supports, a hollowed strake will hide the upper elevator horn. assembly cannot take place until after the covering.

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below the other two sections in progress also the power box incorporating motor mount and battery box which will take a 4s lipo..working out the middle section is proving a bit long winded but I'll get there .. more soon

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  • 2 weeks later...

A bit more progress

U/C plate 1/8th ply with 1/8th ply backing and a brass bracket for the lower strut support

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instrument panel and housing/coaming

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instrument panel photo when glued in it will have a perspex cover

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windshield will sit on the coaming and against 1/8th balsa cabin front

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firewall with battery box aperture and nose leg mount

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Nose leg showing brass wheel saddle and ali nose leg with piano wire insert

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ridiculously large wheel 4" lightweight foam

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mid section cabin area on it's gangly bush plane U/C stands about 7/8 inches above ground should put it in the upper atmosphere before it is airborne

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  • 3 weeks later...

Another update although there appears to be no interest ,I am trying to finish this for the RCME Greenacres flyin as it's part of this years mass build.

anyway enough drivel . below are the flaperon support legs

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another view along the length

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wing centre section this will be fixed permanently to the cabin

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side view showing profile and the upvc box section to stop the wing rotating when slid in place

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cabin section fixed in place also rudder and elevator servos in place..motor box/mount fitted and glued now to construct the split cowldscf0519.jpg

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doors made and glazed not sure if I'm going to try to hinge or not may just use servo screws to fix in place

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flaperon servos mounted on ply plate will connect to flaperons via ball joint and rods and a control pin will engage with the flaperon when wing is slid in place (confused so am I ) .plate will be screwed in place for access,there will also be an access plate on the upper fuselage

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ESC mounted underneath the battery box/motor mount

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Great model.

Rest assured there is plenty of interest! However it could be that spacing out the photos etc over a period of time -instead of all at once- would get more 'Latest Posts' slots and a bigger audience. .

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Missed some of your updates! Last time I looked the slats were only sheeted on top! surprise

Looks very interesting and quite a nice shape to the fuselage. Looking forward to seeing how you're controlling the slats. I was kind of hoping to get some ideas from other builds for my cub from other cub/stol builds but impatience took over!

Although there doesn't seem to be as much building or interest as last year please keep posting updates & pics. Might not be replying frequently but still following all the 2015 mass builds! yes

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Posted by kc on 06/05/2015 17:40:27:

Great model.

Rest assured there is plenty of interest! However it could be that spacing out the photos etc over a period of time -instead of all at once- would get more 'Latest Posts' slots and a bigger audience. .

thanks for advice and comments KC I will try to bring it bang up to date ASAP

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Posted by Chris Barlow on 06/05/2015 17:44:37:

Missed some of your updates! Last time I looked the slats were only sheeted on top! surprise

Looks very interesting and quite a nice shape to the fuselage. Looking forward to seeing how you're controlling the slats. I was kind of hoping to get some ideas from other builds for my cub from other cub/stol builds but impatience took over!

Although there doesn't seem to be as much building or interest as last year please keep posting updates & pics. Might not be replying frequently but still following all the 2015 mass builds! yes

Thanks Chris ..the slats are fixed as per the fullsize aircraft in normal level flight they operate as part of the wing but in take of at a high angle of attack they are hugely effective as in landing ,the angle and shape create a venturi so air is forced at high speed over the wing that combined with the full wing flaps allows take of angles of about 30 degrees and take of distance 3 times the length of the plane .do a google of the zenith 701 and 750 .hope that helps

Martian

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