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The Ohmen


EarlyBird
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1 hour ago, Peter Miller said:

Mine was ic and everyone was amazed at how safe it was on one engine.it was hard to tel which engine had stopped and it was safe to turn into the dead engine.

 
Of course this doesn't apply to electric as it is always on two motors

 
-----Original Message-----

 

Peter....apart from two things, one I have had more electric one engine dead sticks than IC on twins (perhaps why I use Laser engines in preference) and secondly I have the TX set up to dead stick one electric motor so I can practice in the future (with the ability for restart if things go really pear shaped!).

 

I was hoping to encourage Earlybird to the dark side of twins ?...oh and yet more Peter Miller designs ?

 

 

Edited by Chris Walby
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Just checked and Sarik don't do the laser cut parts. GTC will have to wait until I have more experience and progressed to building from a plan.

So far.

Ballerina

RF-4

Swizzle Stick

The Ohmen

Rhapsody

and another plan pack on the way (Peter's of course)

 

I had toyed with the idea of building all of Peter's designs but not only are there something like seventy on Sarik there are also other publishers, Rhapsody came from Doolittle and they have others. I gave up on that idea and decided to build as many as I can while I can.  ?

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1 hour ago, Chris Walby said:

EB, that's why I said to contact me...I have access to the cutting files and a contact who can laser cut the GTC parts for you + a spare canopy should you need one of those.

 

PS I waited for two years for Sarik to promise and not deliver on a kit for the GTC. ?

I completely missed you generous offer? I just don't read properly which has been a lifelong issue.

? a twin would be a new challenge, I'm always up for a challenge.

I only have two models in the queue but Rhapsody looks like it will take some time.

No rush but ok.

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4 hours ago, EarlyBird said:

J

 

I had toyed with the idea of building all of Peter's designs but not only are there something like seventy on Sarik there are also other publishers, Rhapsody came from Doolittle and they have others. I gave up on that idea and decided to build as many as I can while I can.  ?

Only 193 published so far but a few are in the USA. See Outer Zone

 

 

A few of those 193 are duplicates in other countries and a a couple are resurrected vintage designs

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  • 1 year later...

Having flown the Ohmen for some time now it's now in the workshop for repairs. I am taking the opportunity to make some changes and sort a couple of self inflicted issues.

 

I have been practicing for the B test with it and due to my lack of rudder experience I used rudder trim to achieve vertical flight for the stall turn. This works and gives perfect infinite vertical flight but the stall turn only works one way, the opposite way to the rudder trim. Sorry Peter but due to my lack of experience I am putting in 2 degrees right offset on the motor.

 

In winds above 10 mph it will not taxi back so I am changing the skid for a steerable tailwheel.

 

I am in the process of extending the nose, yes I should never have shortened it by 15 mm, my hope is that none of the 80 grams of lead will be needed in the cowl. There is also the option to move a servo from the tail into the fuselage, we will see how the plan works out.

 

My final change will be to put the C of G at 25% of wing cord. I started at 30% and have gradually moved it forward. Whatever you have been told before about a safe starting point for the C of G being on the spar  is not true for Peter's designs. At 30% it flies but has a horrible habit of dropping a wing which means it has to be watched constantly. I fitted a stabilised receiver, which cured this tendency but as I moved the C of G forward the bad habits disappeared and there was no difference in the way it flew with stabilised switched on or off.  It's now a joy to fly or was until a landing on Tarmac turned into acrobatics.

 

Steve

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My Ohmen is exactly at 25% CG without a gram of lead. It will be a bit more noseheavy with fuel, but I don’t think it should be a problem. With the FS26, I placed the rudder and elevator servo in the tail. 1000mAh batt is below the fuel tank. 

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  • 3 weeks later...

I moved the motor forward to the design position plus 6 mm just to make sure, which involved extending the battery hatch.

 

IMG_20230212_105008.thumb.jpg.6229f796d2e188483e90ae1b857732b2.jpg

 

IMG_20230213_091140.thumb.jpg.90a50bfc0c7c9b141538cf04ee92b3d9.jpg

 

The ESC has been moved as far forward as possible under the motor as I wanted to make certain.

 

The Cowl needed recovering which is now done and it's ready to fly again.

 

It does not look as pretty as it did due to the patched covering which makes it well and truly my Winter hack.

 

Steve 

 

Edited by EarlyBird
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  • 6 months later...
On 19/02/2023 at 14:37, EarlyBird said:

It does not look as pretty as it did due to the patched covering which makes it well and truly my Winter hack.

But maybe not judging by these recent flying shots.

 

image0.thumb.jpeg.4f65acb174731ac6bd54eb822dfe25e9.jpegimage1.thumb.jpeg.3cb5ef5ad128947c5732d395c9f5f5ca.jpeg

 

Looks fine at fifty feet even though it's a bit worse for wear. A big thankyou to Mike Mennell for the excellent pictures.

 

Steve

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  • 3 months later...

562 mm 22" is the width from root to last rib.

Set up a jig and cut six spars.

Cut two 100 mm1/16" sheets to this width then cut off a 17 mm strip for the TE cap strip,

Glued the spars to the edge of the LE and TE with the help of a ruler, 

Test fitted the ribs to locate the TE,

 

IMG_20231215_090400.thumb.jpg.a801b975f7215957cd95dd4b2acf0e7d.jpg

 

Glued the tip rib,

IMG_20231215_090437.thumb.jpg.cdcfdc2094be9788c4c2924452c98d2e.jpg

 

and started cutting the shear webs,

IMG_20231215_090451.thumb.jpg.ee24f9f5119f9d8b071deb55e93f63b6.jpg

 

The root rib will be at an angle for the required dihedral.

From the plan it's 3/4" at 22" from the root so 2 degrees say, by rule of thumb.

 

More shear webs to make for both wings including the dihedral one.

 

Steve

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Shear webs completed and test fitted.

 

IMG_20231216_074336.thumb.jpg.fd7a265f8fcbf1f73493a6f2c3538702.jpg

 

Started with the glue on the web then butting up the next rib.

IMG_20231216_075629.thumb.jpg.762e92d68479667a60ad23402614bf48.jpg

 

Continued adding webs and ribs. Here we are half way.

IMG_20231216_085132.thumb.jpg.d6c2b7711ff8ab3d915d200c28656f8d.jpg

 

and all done waiting for something

IMG_20231216_095211.thumb.jpg.8e0c982ba9afcb380816acb3aaf68147.jpg

 

Ah yes glue to dry.

 

I can't add the root rib until the paper tube is installed.

 

Steve

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Top spar added using clothes pegs to clamp the shear webs to the spar, saves buying 2" bulldog paper clips.

IMG_20231217_100828.thumb.jpg.279634cd90631a28f300a84f216ff84d.jpg

 

and dihedral braces glued. I also remembered the paper tube but should have done it after the braces because it's in the way of the clamps.😳

IMG_20231217_100754.thumb.jpg.b707473f327d2d25fc110e4e89079619.jpg

the bottom brace was kept up 1/16" using scrap ply, which I had just pulled back when the clamps were in place as I didn't want it to be permanent. 🤣

 

Steve

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Personally I don't pull up the lower leading edge sheet until the leading edge is glue in place.

Also the second root rib is not glued in place until the wings are joined. That way you get a perfect fit at the root.

Th spar webs are not glued in until both top and bottom spars are  glued in.

But then I do things the easy way

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 Thanks Peter.

 

The leading edge cut at an angle then sanded to shape with the aid of a few test fits, Once happy I turn the LE full sheet over and cut to width, again at an angle, then glue,

 

 

 

IMG_20231218_164423.thumb.jpg.106377e625dfd221da9f565f6160865c.jpg

 

IMG_20231218_164546.thumb.jpg.5157f48ccd6b217612b1cb936ac532a6.jpg

 

Not a good photo but shows the LE and the packing.

 

After shaping 

IMG_20231219_094016.thumb.jpg.9fb7d47b6c50773807c2bafd3ca8fda1.jpg

 

IMG_20231219_094055.thumb.jpg.460ae6beee3bf7d0c28e7ff1913d05c3.jpg

 

That's better.

 

Steve

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I have to work this way as I have great difficulty using pins.

 

Finished shaping the LE and TE aileron spar then added the scrap balsa for the hinges and wing plate.

Then added the TE cap strip, again 17 mm cut off a 100 mm sheet which leaves enough for the LE top sheet.

 

IMG_20231220_161456.thumb.jpg.f133a80da771a3bc5b87984a8508c878.jpg

 

I spotted a mistake. Too late now. 😭 For me anyway but John my club mate has not got this far.

 

IMG_20231220_161529.thumb.jpg.5b263e8e549b4b62cbffdcd47cf84ec5.jpg

 

Maybe.

 

LE top sheet next. 🤔

I have been thinking of some more bright ideas 💡 😭

 

Steve

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