By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by CML

Design & Build Sport Twin

Sport Aerobat for 2 x 40s

All Topics | Latest Posts

Search for:  in Thread Title in  
Jon - Laser Engines24/06/2019 09:56:57
4801 forum posts
179 photos

Depending on the sizes you might be able to 'vac form' your own cowls. All you need to do is make one wooden cowl plug from as much solid material as you can muster. Then cut the bottom off a 2l drinks bottle, shove your plug inside and hit it with a heat gun. The plastic bottle will shrink nicely around your plug and once you cut it free you can use it again for cowl no2.

If you are looking for a 100% perfect finish then this probably wont do, but if you want quick cheap and functional then it might be worth a shot.

Nigel R24/06/2019 12:36:44
avatar
3066 forum posts
475 photos

That's a thought. How would you finish a shrunk bottle? I'm not too familiar with the technique (read: never done it).

Nigel R27/06/2019 08:47:24
avatar
3066 forum posts
475 photos

Made a started on some cowling. First job, cut some noserings (turned on a drill), and then sort out the cutouts in the plastic spinners. As there were four cutouts I made a sanding tool from some scrap balsa shaped to the cutout I needed and just started scraping away at the spinner until I had four identical cutouts.

When that was done I could get the engines bolted in, with the nosering stuck to the spinner. I borrowed an idea from one of Pete M's build blogs - use some scrap 1/8 between the spinner the nosering, the nosering is held in correct position.

I've only got as far as the side pieces here (3/8 sheet):

20190626_232427.jpg

20190626_232451.jpg

That looks decidedly odd with the perspective, but the motor on the left is dead ahead no rightthrust!

Anyway. Now the sides are in (and it took a while to fettle them in to position) the bottom can go on, at which point everything should be nice and solid, and I can remove the motor and put some triangular stock in the corners and get the top block on.

Then time for some more carve and sand yes

Nigel R29/06/2019 12:29:22
avatar
3066 forum posts
475 photos

20190628_223128.jpg

20190628_232502.jpg

20190629_110354.jpg

20190629_114920.jpg

Excuse the umbrella growing out of the port wing!

Got a good chunk of the block carve and sand exercise done. It's surprisingly hard work especially in the heat today! I will probably put the nacelles to one side now and get the nose on the main fuselage up to a similar point.

Nigel R03/07/2019 23:00:45
avatar
3066 forum posts
475 photos

Changed my mind a bit and did another hour or two of sanding in the nacelles. Pretty much done with them now bar cutting out the opening for the motors.

20190703_223741.jpg

20190703_223817.jpg

Nigel R06/07/2019 08:04:52
avatar
3066 forum posts
475 photos

Getting the remaining nacelle jobs finished.

Some tank hatches:

20190704_225300.jpg

I was going to make them from liteply but I've run out, so I used 1/16 birch ply laminated to some leftover wing sheeting. They're a bit heavyweight for a hatch but they also retain the tank so need to be a bit tougher than usual.

I also hogged out the cowl area. Had to remove rather more material than I'd hoped...

20190705_224942.jpg

It still needs a little more relieving around the throttle arm and front of carb.

20190705_225044.jpg

After that, I realised I wouldn't be able to get the silencer on...

20190705_225025.jpg

...without hacking away another lump on the port side, to allow access for the silencer retaining screws. Hey ho.

After those fixes, I should have a pattern to copy on to the starboard nacelle.

There are not that many big woodwork jobs remaining - make and fit the fin and rudder, and do the block, carve and sand at the front of the fuselage - before the last leg of gear install and finishing.

Nigel R09/07/2019 06:48:02
avatar
3066 forum posts
475 photos

A bit of trimming later:

20190706_102309.jpg

 

And now back to the fuselage...

 

20190708_232805.jpg

That needs rounding off. It's just been razor planed so far.

The nose area is tack glued on. It will be made removable. Then I get easy access to the nose leg and a possible location for rx battery or the rx satellite.

Edited By Nigel R on 09/07/2019 06:49:30

Nigel R18/07/2019 06:57:14
avatar
3066 forum posts
475 photos

Fin and rudder are done so time for Some more carving at the back of the fuselage:

20190716_225318.jpg

And made a start on installing the servos:

20190717_230702.jpg

Nigel R12/08/2019 15:11:08
avatar
3066 forum posts
475 photos

Seems ages since I last updated. I've been doing some small jobs finishing off a lot of the woodwork. Shaping the wingtips, tapering controls, attaching the tail feathers, making tank hatches, fitting in the control run outers, control horns, wing mount stuff sorted, all the kind of bitty jobs that tend to accumulate at the end.

There is little woodwork left - main jobs are to get the fuselage nosecone mounting blocks done, glue on the nacelles and sheet the fuselage underside - before getting to covering and fitting out.

20190810_223110.jpg

Torsten Spitzner12/08/2019 15:45:40
avatar
24 forum posts
17 photos

Coming along nicely. It looks like a winner to me.yes

Denis Watkins12/08/2019 16:41:33
3884 forum posts
60 photos

I can see myself, stood in front of that masterpiece Nigel, on my model stand, with starter in hand.

Am right handed, so with the nose cone on my right hip, I would start the motor to the right of picture 1st.

Then would move this way, to present the starter to the second motor.

From there I would move to the rear of my sturdy trusted model stand, and feel the draught from the 2 x 40s

Oh what a dream

Super well done you.

Chris Freeman 313/08/2019 05:04:54
260 forum posts
335 photos

Very nice Nigel. A very nice looking aircraft that is very well made. It must have made quite a dent on your balsa stock.

Piers Bowlan13/08/2019 11:21:14
avatar
1871 forum posts
45 photos

Beautiful work Nigel, very neat. Love it. yes

Nigel R14/08/2019 15:47:07
avatar
3066 forum posts
475 photos

Many thanks gents smiley

Denis I have had the same thoughts a number of times throughout the build - the day is not too far off now!

Nigel R15/09/2019 07:37:39
avatar
3066 forum posts
475 photos

Crikey. A month since last update!

Well, I have not been too idle. The airframe is finished and covering started. One thing I have noticed with the nacelles on the wing is that there are a lot more nooks and crannies to get the film in to and this is taking "a bit longer" than expected!

Anyway. Part progress on the nacelle:

20190914_220509.jpg

As usual I am going for a white base with some coloured flashes on top.

Must find a bit more motivation from somewhere. Covering is probably my last favourite stage of a build if I am honest.

However on the plus side as soon as the film is on then it is time to go and fly smiley

cymaz15/09/2019 08:30:46
avatar
8670 forum posts
1177 photos

With my multi engine planes, I have a set routine when running them up. I’ve tuned mine to be off peak by 4/500 rpm. They go a bit lean in flight and you don’t want to over stress them.

I start them up and check them one at a time. Stop the first one before starting the other. That way you can tell what’s going on. Then run them both up. I don’t want to get all my engines to run at the same rpm at WOT. I’ve been told that the thinking behind running the engines t the same rpm starts up a harmonic resonance with goes through the framework . There is a definite “wa woo wa woo w woo” sound if you get them exactly the same.

Be very careful about avoiding getting any dirt into the fuel lines and tanks. I never put my fill tube on the ground and always hang it up in the start box after filling.

Always have an escape plan rehearsed just in case one engine quits. Other than that .......good luck and a great buildyes

Peter Miller15/09/2019 08:43:19
avatar
10193 forum posts
1192 photos
10 articles
Posted by cymaz on 15/09/2019 08:30:46:

goes through the framework . There is a definite “wa woo wa woo w woo” sound if you get them exactly the same.

buildyes

Interesting! My parents said that the Italian bombers made that sort of sound when we were being bombed in Alexandria in Egypt in 1940. (I was only 2 1/2" at the time)

Shaun Walsh15/09/2019 14:30:27
183 forum posts
12 photos
Posted by cymaz on 15/09/2019 08:30:46:

With my multi engine planes, I have a set routine when running them up. I’ve tuned mine to be off peak by 4/500 rpm. They go a bit lean in flight and you don’t want to over stress them.

I start them up and check them one at a time. Stop the first one before starting the other. That way you can tell what’s going on. Then run them both up. I don’t want to get all my engines to run at the same rpm at WOT. I’ve been told that the thinking behind running the engines t the same rpm starts up a harmonic resonance with goes through the framework . There is a definite “wa woo wa woo w woo” sound if you get them exactly the same.

Be very careful about avoiding getting any dirt into the fuel lines and tanks. I never put my fill tube on the ground and always hang it up in the start box after filling.

Always have an escape plan rehearsed just in case one engine quits. Other than that .......good luck and a great buildyes

The noise you can hear are beats caused when the two engines are running at almost the same speed but not quite, the smaller the difference in speed the lower the beat frequency until it disappears when the engines are at exactly the same speed.

Nigel R16/09/2019 17:16:37
avatar
3066 forum posts
475 photos

Thank you cymaz

That sounds a sensible startup routine for multis. Having a good one seems to be a recurring theme, whenever I read anything about them. I think I may be investing a couple of sessions getting a routine going.

I'm paranoid about dirt in the fuel. Filtered from container I buy on its way into the jug that lives in the flight box, filter before the pump, filter between tank and engine. Probably overkill but so what.

My escape plan is just to deadstick it down. It should be fairly mild mannered with the rectangular wing. Practice approaches are high on the agenda for the first few flights.

cymaz16/09/2019 20:18:10
avatar
8670 forum posts
1177 photos

yes

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of RCM&E? Use our magazine locator link to find your nearest stockist!

Find RCM&E! 

Latest Forum Posts
Support Our Partners
Slec
CML
Pepe Aircraft
Wings & Wheels 2019
Gliders Distribution
Cambridge Gliding Club
electricwingman 2017
Sarik
Advertise With Us
Latest "For Sale" Ads
New Poll - Sticky situations...
Q: How often - when using superglue - do you end up with it on your fingers?

 Every time
 Occasionally
 Sometimes
 Rarely
 Never
 Wear rubber gloves

Latest Reviews
Digital Back Issues

RCM&E Digital Back Issues

Contact us

Contact us