Here is a list of all the postings Dean Sarelius has made in our forums. Click on a thread name to jump to the thread.
|Thread: The Ohmen|
Thank you everyone for your positive feedback.
The only mistake I made was with the undercarriage so had to peel off the film and cutaway into the fuselage to fit some extra ply mounts. For most of my build it always seems to be the undercarriage that creates the most grief. I couldnt even find the right wire so ended up picking some up at the local scrap metal yard and when I went to purchase the rods he wasnt sure if they were aluminium or magnesium. I guess if they are magnesium and if it should go down in flames then it should be quite visible ha ha.
Thought I would share the pictures of the Ohmen.
Just on the last leg of setting up, waiting for the battery (2200mAhr, 11.1V, 30C) and new push rods to arrive before completing the assembly and testing.
Also did you make some small cut outs on the wing for the servo leads..?
I plan on doing the covering and final assembly next week so fingers crossed.
I really hate adding weight so will also consider to cut out the bulkhead for the motor and move the motor closer to the wing but I guess that could be a little drastic.
Just doing a dry fit with the motor mounted and the tail parts in place and the CofG is spot on which has got me really worried as I don't have a battery fitted as yet..?
Guess I will be having to add some extra weight into the tail when I go to fit it out with the electrics or perhaps a smaller battery.?
Just want to know if I should be making some cut outs on the wing for the servo leads..?
I assembled the hatch latch you kindly provided and it worked a treat.
Here is a picture of the latch below.
Its very easy to simply pull the wire and the hatch is free to lift out.
Also I like the fact that there is nothing protruding above the hatch.
I will make up one of these which will fit nicely into the cockpit.
Many thanks again,
Thank you for all your positive comments on the plane.
I was unable to purchase a hatch clip aka retainer and have been racking my head as to other options.
I see one of the other builds used magnets but I would prefer a mechanical method so was just wondering what if any are the alternatives..?
The laser cutter I have is the Chinese made K40 which I purchased from ebay for around AU$550.
As I prefer to keep things more simple the model I chose is with the analog dial not the digital version.
You will need to invest in making some additions like adding an air compressor, hose and jet as well I would recommend to add LED lighting and replace the cutting table with a sheet of perforated steel with magnets to clamp your pieces, all up extra AU$150. I can send you some pics of the mods which I made if you are interested just let me know.
With these mods I find it to be a very good laser cutter and engraver. I never use it at maximum power normally I cut at about 30-50% maximum. At 50% for example soft balsa up to 3mm is a single pass while 3mm plywood requires a second pass.
I get the plan scanned at my local Office supply shop then I use Solidworks to trace allowing about 0.1mm for the cut. After tracing I copy and paste, laying out the traces into Inkscape with custom dimensions set for the width and length of the balsa wood I will be using for cutting. Inkscape allows you to change the colours of the traces which the K40 laser cutter automatically interprets Red for cutting and Blue for engraving.
I could share the Ohmen files here if anyone is interested in doing it themselves just let me know.
All in all if you plan on building a few models then you will find it a good investment.
I have set up the laser cutter in my garage so should I need to re-cut any parts its super quick and great for all those plywood bulkheads.
There is also a lot of video and user tips on the net.
I have completed the cowl but slowing down now as I try to work out a good colour scheme.
Also since I will be covering the fuselage with metallic I was thinking of covering the cowl also but I think it will be easier just to paint and would welcome any feedback on this..?
Here are some pics of the cowl and the plane as it is more or less ready for covering.
Thanks Peter and Trevor,
As I will be placing just one pilot into the rear seat I will make the hole in the front seat same as per Trevors pic.
I will also place the re-enforcing for the motor bulkhead.
I dont intend on having holes where the pilots will be seated so this is why I asked the question...?
Thanks for the heads up.
I use slow curing epoxy for all the bulkheads and since the engine bulkhead is mounted directly to the inside plywood laminate sheets there is plenty of strength provided by the epoxy joint so no need to add any stock. By the way the epoxy I use is called Bote-Cote and its the same as that which I have been using for building plywood boats.
You can see some of the boats I have built on my webpage, www.boatandhobbies.com.
One of the advantages with Bote Cote is the long curing times which can vary depending on the ambient temperature anything between 2 hours and 10 hours on a cold night. The longer curing times allow for longer setup and when mixed with a filler provides an extremely strong joint.
I think I will take Peters advice and laser cut a slightly larger cowl ring.
Regarding the air flow do you think it would be advised to add an exit behind the wing perhaps..?
Thanks again for all your good advice.
Thanks for the quick reply.
I am unable to pack the prop forward for fear of running out of thread.
I think I will take up your advice and open up the cowl ring.
I might just change the shape of the cowl to allow more air to flow around the motor what are your thoughts on this as I think there will be very little air flow around the motor if the cowl is to restrictive..?
I am just setting up to build the cowl for the Ohmen.
After fitting I find there is very little space between the cowl ring and the motor. If I was to provide a 1mm gap between the spinner and the cowl ring the cowl ring will be rubbing up against the motor.
Just wondering if anyone else has run into the same problem and if there could be any easy fix..?
I sand off the burnt edges with 220 and on account of the laser I also square off the edges before gluing.
The balsa cuts much quicker so tends not to get as burnt as the ply.
Here are the pics from my album.
OK not sure what happened with the pictures so have provided the links here below.
Laser cut bulkheads
Wing halves epoxied together
Wing and fuselage 1
Wing and fuselage 2
Here are some pics of the Ohmen so far.
Parts have been cut with my Chinese 40W laser cutter and the bulkheads and wing halves glued with epoxy. Will make a start on the undercarriage next and will take Martins lead and mount it to the outside.
Want the latest issue of RCM&E? Use our magazine locator link to find your nearest stockist!