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Rojair ME163 build

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dave windymiller19/04/2020 21:26:41
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134 forum posts
160 photos

During this downtime with the virus, ive decided to make a start on this original kit dating back to 1979. Originally i was going to make molds off the ABS parts but decided that lifes too short!

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The kit is as new except for the browning of the decals

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Still trying to decide on what motor to use. I have an sc25 and os20fp. I know Rob Millinship, the original designer of this plane, used a G20-15 super tigre and another hot 15 (KB15 rings a bell?) with no throttle. The SC25 is some 70g heavier than the OS. I want to keep it light but have a throttle.

Will ponder that one and scour ebay for any hot 15 to 20s.

The kit includes a mechanical mixer but i will use mini servos with mixing from the transmitter which will save some weight,

Job one LE and TE on wings.20200419_205051[1].jpg

ttfn

Dave Windy Miller

J D 819/04/2020 21:54:40
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1664 forum posts
82 photos

Watching this with interest. I had the Rojair Cadet 62 at that time. [2nd RC plane and still have the wing on a Hiboy fuzz used now and then as an engine test plane]

A leaflet of Rojair's other models came with the Cadet and I dreamed about tearing up the sky with a 163.blush

Peter Christy20/04/2020 08:08:18
1921 forum posts

Good Grief! I had one of those, back in the day! Mine was powered by a Super-Tigre .21 (more than adequate!).

It was brilliant in the air. The difficult bits were 1) getting it there in the first place and 2) getting it back down afterwards!

It required an almighty hurl to get it airborne! The only member of our club to successfully launch it was Dave Wilshere. Plenty of people tried, but only he succeeded!

Landing was also an issue! Admittedly our "patch" at Croxley Moor was small and uneven, but at first contact with terra firma, all semblance of control disappeared, and it had more in common with a pebble skipping across the sea than an aircraft landing! I gather the full-size was very similar....! smile o

I ended up giving mine to Dave! I now have one of the HobbyKing electric ones which is much more manageable, and a delight to fly.

Best of luck with it! Some kind of bungee might help with the take-off. Otherwise, find a local javelin thrower with large hands.....! laugh

--

Pete

dave windymiller20/04/2020 22:40:21
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134 forum posts
160 photos

Thanks for that. The kit comes with the underpan that forms a dolly. Instructions are on the plan how to build it but I just need to add the axle & wheels. I may try that approach as my own launching arm isnt what it was.

Leaning towards the sc25 with weight saving from the servos, mixer etc. The kit comes with 2 nose cones so i can try various options.

I kept feeling guilty by building a mint in box historical kit but im over that now.

Dave

Steven Webb (Steve Webb Models)20/04/2020 23:39:00
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302 forum posts
103 photos

I learned to fly multi on a Rojair 62 from Alpha Models in Ellesmere Port. I had a second Rojair Cadet to build , better and power more. Mistake. My first Rojair which survived into the 90's training folk , that had a OS Max 40 RC and it was perfect. The second had a 40 FSR and I was at the untidy aerobatic stage of learning. I ripped the wings off it.

I think I should have gone for the comet ... LOL. Im posting as this was on the wall of the shop. It was there for years or at least the same kit was. I expect it sold and another was placed there. The day it came to buying it - I went in and it wasnt there and worse. Rojair had burned down.

So that was that. I thought the kits were great at the time.

Steve

dave windymiller21/04/2020 22:30:19
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134 forum posts
160 photos

I agree Steve, the quality of this kit is very good! The vac formed parts are lovely quality. I can remember Rob Millinship copying an aeromodeller ME163 glider plan in the late 70s as basis for this model! I still have that very plan! Rob is a talented chap and his move to full sized aviation was a big loss to aeromodelling!

This is first kit ive made in over 20 years and being unorthodox in construction, i'm following instructions to the letter. This is good as it forces through those pet hate steps that usually add 6 months to a build! eg control surfaces (dont know why?)

Wing nearly done. Outer elevons have increased reflex. Plan also shows option for single piece elevon but that doesnt look as good

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Fus trimmed to make TE sharp and holes cut out where required to enable wing to be finished off to fit (another step i would procrastinate at for fear of cocking up).

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The fin has a box section below which fits inside main body for strength!

Windy

dave windymiller23/04/2020 22:13:32
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134 forum posts
160 photos

I think ive decided to go with the OS FP20 initially then move up to the sc25. Many years ago i "tuned up" this 20 engine by drilling out the exhaust tail pipe of the silencer. Since then it doesn't develop enough pressure for a constant fuel feed so rarely got used. Thankfully there was a silencer on ebay for a fiver so thats on order!

Front bulkhead/engine bearers/tank assembly glued into lower fus. This extends right down into the front of the skid to add strength

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Wing seating dry fitted.

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Next to add trailing edge/control surfaces

Capt Kremen23/04/2020 22:39:19
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411 forum posts
169 photos

Memories ... I built one of these beauties.

At the time, just finding an adhesive which would stick the fuselage halves together sufficiently strongly posed a problem. No doubt modern adhesives are now fully capable of achieving a robust bond.

Mine needed a hefty, but good quality launch to get it aloft, (OS 25FSR powered) but once the prop got on its 'step', the craft fare motored around the sky just like the original full-size probably did.

Good luck, enjoy!

John Tee24/04/2020 15:19:52
906 forum posts
73 photos

Rojair did their own glue Rojair Roket. Probably an early cyano.

John

dave windymiller24/04/2020 22:13:39
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134 forum posts
160 photos

The other Rojair model i am finishing (ME109G another thread in this section) dates back to the early 80s and the vac formed parts were glued together at the time. 40 years on I expected these to fall apart but after some flexing i concluded were still sound. The glue looks like Cyno and quite hard.

My gut feel is cyno would be too brittle but i also suspect it partly dissolves the plastic which would helop

As you say they recommend Roket which the blurb says was developed "in conjunction with Loctite". I will do some experiments with offcuts before committing!

Has anyone got experience of this model with the dolly for takeoff?

John Tee25/04/2020 18:46:43
906 forum posts
73 photos

I had one many years ago. It flew a treat. No throttle just flat out for maybe 5 minutes. I was a lot younger then and my reactions were quicker. Can't remember how I launched it to be honest, but it wasn't a dolly. My Durafly 163 has a releasable dolly but have yet to fly it.

John

dave windymiller10/05/2020 21:33:50
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134 forum posts
160 photos

I can confirm Cyno is marvelous for sticking the ABS parts together. It melts the surface so gets a very good bond. I use thin stuff for the initial joint then thicker cyno as a fillet. Here's the fin now fitted to the upper fus with a scrap insert under the fin.

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Control surfaces added, each section having 1.5mm reflex compared to its inner neighbor.

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Ive gone back to the OS Max 20 as its a much better fit and some 15mm shorter than the SC25. Can upgrade later. Throttle servo awkward to access under the fuel tank but not impossible.

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Final shape emerging. Dolly also taking shape.

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Edited By dave windymiller on 10/05/2020 21:37:11

dave windymiller23/05/2020 11:37:07
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134 forum posts
160 photos

When I glued the bottom half of the fus to the wing i noticed that the fus width was narrower than as shown on the plan by some 15mm. As the vac formed fisalage half was quite flexible it took no effort to simply widen the fusalage as i glue it. BIG mistake. When i came to fit the top half, it would not stretch to match. I also noticed that the stretched bottom half also caused the nose and tail to flex upwards. Fitting the top was a right mare involving surgery to remove material from the rear mating joints as they now overlapped. I also had to cut out segments of the wing fairing to get it to match. Again cyno appears to be ace with this plastic!

The tail jet pipe was now anything but round with the rear of the plane some 6mm shallower than designed. I opened up the hole again but this hole was not flat but scalloped with the fin fairing. Fortunately i found a lampshade nut wrench made of white abs that fit the hole perfectly, making it round and looks like a jet nozzle.

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I was planning on having a servo dolly release but after studying the plans i decided the standard method was so simple it would be reliable. The kit only give you the vac formed pan so the other bits are from stock! You have to make a pivot block from nylon (i used ally as i had some) to trail a 1m length of piano wire. As it takes off the tailing wire pivots downwards and releases the from the plane!

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Ive also bought a nice looking OS25FP which is dimensionally identical to the fp20, a bit lighter and 20% more power. Its the same piston/porting as the famous os25FSR but shorter due to lack of crank bearing. This is the final engine choice!

 

Edited By dave windymiller on 23/05/2020 11:41:38

dave windymiller29/06/2020 15:38:05
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134 forum posts
160 photos

Ive now filled the wing joints, cut open the cowl for the engine and assembled the cockpit

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The cockpit is balsa then two clear vac form layers. The inner vac formed is painted except for either side of the glass bullet proof glass. This gives a very natty looking glass screen. The outer will be painted except for the main cockpit glass and two little windows that a fuel tank can be seen through.

A longer engine would not work in this model so the fp25 looks to be the right choice!

There a Komet kit on Ebay at the moment but you will need to sit down to look at the (optimistic) price!!!!!

Rojair komet on ebay

Edited By dave windymiller on 29/06/2020 15:46:06

dave windymiller28/10/2020 21:20:37
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134 forum posts
160 photos

This project has been delayed due to covering the wings with lightweight glass cloth. After a few days i decide to trim the cloth using wet n dry at the edges. No way could i sand it. The cloth epoxy was still gummy all over. Arrggghhh. I could leave finger prints in it even after a week in the airing cupboard.

I tried to remove the gummyness with cellulose. Ive tried coating the cloth with various hardeners and even considered razor plaining the lot off. I stopped short of the razor plain and did what most would do, shove it on a shelf and forget it!!!

I think i know what happened, i got distracted whilst mixing the epoxy, the scales turned themselves off and i messed up the ratio by estimating! Should have chucked it and started again.

I looked at it the other day and it looks like its eventually set (happy days).

Time to continue with it! 2K Primer next!

 

 

Edited By dave windymiller on 28/10/2020 21:21:57

Nick Cripps28/10/2020 21:44:26
96 forum posts
65 photos

Good to see you back on this, Dave.

Paul Marsh03/11/2020 20:22:11
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4112 forum posts
1245 photos

have you still got the outer wing skins? someone has got 3 kits, but the vaneer has delaminated and intends to recover the wings in balsa, but needs the outer to form the wings.

dave windymiller05/11/2020 23:13:18
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134 forum posts
160 photos

Hi Paul. Sadly no. Once the wings were joined to the fus, the blanks were binned. I had a similar issue with the rojair me109 (another thread on here). I used the foam core to make templates to cut new wings from foam. I didnt use the new cores just the blanks to reskin the original cores.

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