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FMS Alpha Jet 2ch R/C conversion for PSS


Phil Cooke
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Hi Haoyang,

sorry for slow response I've somehow missed your postings this past few days...

To answer your questions - yes the incidence and the CoG were both left unchanged in the conversion - and as for the black paint - I simply primed over it then painted on top of the primer... it covered well, so no need to try and remove it.

Don't forget to post an image of your finished AJ!

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Got two delivered, assembled one as chuckie in seconds, gave it a not even girlie strength push..................and walked the 100 foot plus down my garden to retrieve it from its arrow straight flight and soft level slide to a stop landing.

Blimey!

One of them might be getting carved out a little more, as I have this "teeny" EDF unit doing nothing, and can't always get to a slope.

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Well, once I was told that for the PSS type of gliders, the incidence of the stabilizer should align to the flat bottom of the wings, so before I read Phil's reply, knowing no better, I had adjusted the stabilizer incidence accordingly, which involved shaving off the foam above the stabilizer, and filling up the resulting gaps below.stab incidence adjustment

This is how I arrange the gears. I link each side of the elevator with a separate carbon rod.radio gears

The battery is E-flite 200mah 2S, commonly used in their micro planes, like UMX Beast.under the canopy

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For my first build, I decided to get it into the air as soon as possible, so no paintings, no carbon reinforcements, and no dihedral adjustments to the wings and the stabilizer. I applied the stickers for the colors and as a cheap way to stiffen the surfaces.

The plane ends up very nose heavy. I had to add 20 grams of tail weight for balance. In hindsight, I should not place the battery so forward. Maybe I should have run it on a single-cell lipo.

Because of the incidence reduction, its GC is about 1 cm aft of the original position. The pitch is still stable with this new incidence-CG combination. Don't know how the flight compares with the original configuration.

All up weight, including the 20 grams of tail weight, is 133 gram. (The original 5 gram nose weight has been removed.)

It needs more than 10 mph of wind to fly. It penetrates ok, and gets small very fast, maybe due to the weight. It prefers to make wide, smooth turns, like a jet, again this maybe also due to its high wing loading. I think it should be lighten up.

It tends to wave its wings. I think removing the wing dihedral not only makes it look more scale, but will also improve the flight performance.

Edited By Haoyang Wang 1 on 18/06/2017 08:07:56

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  • 5 weeks later...

Just a stupid question, but I'm good with them; are the receivers you using on this model 'park fly' or indoor types? I've not made/ assembled (corrupted) a model like this yet, and want to make sure I get the correct type of receiver and servos.

That would also be Futaba compatible........

Cheers

Ade

embarrassed

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Just a stupid question, but I'm good with them; are the receivers you using on this model 'park fly' or indoor types? I've not made/ assembled (corrupted) a model like this yet, and want to make sure I get the correct type of receiver and servos.

That would also be Futaba compatible........

Cheers

Ade

embarrassed

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  • 2 years later...
  • 2 years later...
  • 4 weeks later...

Now, I know I’m more than a little late to this party but having seen Harry’s Alpha Jet in action on the Orme I fancied building one for myself. Having read through the build logs on here and with much guidance from Phil and Harry along the way I now finally have one ready to fly.

I won’t go through my entire build as it’s obviously very similar to what’s gone before but here are a few photos anyway…

 

The weight of the original glider was 72g.

 

IMG_20220609_080612254.thumb.jpg.77ef5d9c804cb610901e9a7918c1a538.jpg

 

I used flat carbon strip where I could and rod where space was at a premium.

 

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I used 190 micron mylar hinge for the elevators and ailerons but found the width as shown in this photo was way too much, making the hinges too stiff so I subsequently cut them down to something in the region of 4mm wide.

 

IMG_20220619_150530736_HDR.thumb.jpg.ded720d114ba27ea3d13ab144536b561.jpg

 

I used a carbon rod to locate the front of the canopy and magnets for the rear.

 

IMG_20220622_153403405_HDR.thumb.jpg.2761403fbe575e07ae887188511d3ad4.jpg

 

I found the elevator linkage hoop required a good width to ensure the two brass levers didn’t foul at their full extent of travel. (The gap between the two brass levers varies through their travel due to the effect of introducing anhedral to the tailplane).

 

IMG_20220628_152159988(2).thumb.jpg.ab04972845891bd1e265cb02c67da21b.jpg

 

AUW with all the radio gear but prior to any paint was now 97g.

I sprayed the plane initially with a clear plastic primer, followed by a few thin coats of white acrylic primer before applying Tamiya matt white acrylic which then brought the weight up to 101g.

 

IMG_20220701_145013902.thumb.jpg.3fb3b4fa2825a8363b4bda5cee94cc55.jpg

 

Now I was ready for some colour and of course I needed to find a different colour scheme to what’s gone before. As seems to be my way of late I ended up choosing something difficult! The Portuguese Air Force ASAS colours.

 

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I lightly sketched the shapes onto the primed surface using a soft 6B pencil until the proportions all looked about right and then masked up, spraying red first, followed by the green and then black. I used Tamiya matt acrylics and my new spray gun and compressor (Thanks for the recommendation Harry).

 

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There was much touching up of paintwork along the way, partly due to a little paint lift and bleeding under the tape in places but also due to the translucency of the white and red colours in particular. I also found the matt white finish difficult to keep clean during the whole process.

 

Another first for me was making my own waterslide decals although this did require much assistance from our daughter in the Photoshop department. I have to say they went remarkably well and I’m particularly pleased with the chequerboard finish around the nose, something I had previously thought I would have to do by hand using either paint or a Sharpie.

 

IMG_20220719_174948449_HDR.thumb.jpg.08dd38f3cef7c8698f57557d27d3a4e1.jpg

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Once the decals had dried I then gave everything a couple of light coats of clear satin sealer which should hopefully give it a little more durability against any knocks or scrapes, time will tell. Weight at this point now 114g

 

IMG_20220721_123939769_HDR.thumb.jpg.bdd8607753561f5f55b160980fde2444.jpgIMG_20220721_124004379_HDR.thumb.jpg.f2f65aa0b8631e5fb77abddefb0a2c93.jpgIMG_20220721_124038338_HDR.thumb.jpg.76d6f43697b195ed88edf6d3cfbb4ca7.jpgIMG_20220721_124126619_HDR.thumb.jpg.069ef9119869a604a4eeb1bb0f7c626f.jpgP1040290s.thumb.jpg.df89a90e8c52bea7bfde7537ee6aa001.jpg

IMG_20220721_122818327.thumb.jpg.97e691fce673fa885325ef7d27012066.jpg

 

Prior to any paint I thought I had the C of G something close to the 78mm from L.E. figure but subsequently found I needed to add a couple of small masonry nails up front to bring it right meaning my AUW finally is 118g. Not the lightest but not too shabby given the amount of paint! In hindsight maybe I should have tried to install the elevator servo further forwards as Harry did with his and thus negate the need for the nails.

 

IMG_20220721_145556785.thumb.jpg.64a620c1c6254729e2baf7b1962faceb.jpgIMG_20220721_145531101.thumb.jpg.f6aa747e4f1d9f6ea57d59728db4cf92.jpg

 

All I need to do now is get out and fly it, I hope to be able to maiden it in the coming week or two in readiness for the next PSSA event on the Orme.

 

Phil 🙂

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8 hours ago, Rich Griff said:

Site won't let me start s new thread today...

 

And FM's website won't display alpha jet glider info...

 

Are there two sizes of this foam model ?

 

An 18 inch wing span 467mm and a 600mm wing span version please ?

 

Thanks

No I don't think so Rich. The one I have just built was advertised as 600mm which must refer to the overall length, the wingspan is 467mm.

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