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Author Topic: Boeing Vertol CH-46 Sea Knight - My helicopter build  (Read 2248 times)

Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #25 on: December 06, 2019, 10:57:19 PM »

Hi, I dont know how to go about doing that. I did wonder if I could edit the title. As to the lightness, using 1/32 balsa sheet helped, but I should have checked the weight of the scrap 1/16 and 1/8 balsa formers, and how many I was putting in. It waa a delicate structure to work on, sanding it caused a few breakages. Once the outer skins were on, it became less delicate. It is approaching my weight limit already, things always end up heavier than you think. The rear foam section after rough shaping, was over 40 grams. After sanding the outside, this only dropped to 36 g. In an effort to shed weight, I have removed foam and balsa from the inside with 13mm drum sander, this has now dropped the weight to just under 30. I want the airframe to be able to take flying and landing stresses, so I cant lighten things too much. I still have some sanding to do on the nose, then sanding drum to hollow it as much as possible. I still think I have to lose a bit of weight for decent flight performance.
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Martin [Admin]

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #26 on: December 08, 2019, 10:57:14 PM »

Topic renamed....
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #27 on: December 08, 2019, 11:13:12 PM »

Many thanks to Martin for renaming my topic. I will post more pics as things progress. I have cut out the cockpit door windows, cut plastic sheet to fit front window, attached foam sponson tips, filled various areas and remade my undercarriage. I had made a set using 2 layers of liteply and a layer of 1/16 balsa each side for each wheel, I used an old tx aerial for main bit of strut, inside a plastic tube and a lighter spring inside. Kebab stick was used for axles. Total weight 20g.I decided to make a lighter set using just balsa for the wheels and dowel for main strut. I am happy to report a significant weight saving over my original ones. New weight is 6g! A saving of 14g, just for choosing different materials. The whole project has taken on a weight reduction element.
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #28 on: December 09, 2019, 12:00:51 AM »

The tail unit has had 16g of material removed. Not the prettiest, but effective. The forward rotor mast housing has had 3g removed, leaving it at 7g. The wheels and sprung struts on the left are 20g, the wheels and solid wood struts on the right weigh in at 6g. Another useful weight saving.
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tigertiger

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #29 on: December 09, 2019, 05:14:43 AM »

I did wonder if I could edit the title.
   






We can do that for you.
It will change the title of the thread, and every future post.


What do you want the new title to be?
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #30 on: December 09, 2019, 09:07:14 AM »

Hi, Martin has already changed it for me. Thanks anyway.
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #31 on: December 12, 2019, 03:01:58 PM »

A bit more progress over the weekend has it ready for painting. I also did more weight trimming, tiny amounts but it all adds up?
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #32 on: December 12, 2019, 03:45:07 PM »

I painted the cockpit interior black, I did want to build an interior of some sort, but extra weight isnt welcome at this stage. Anyway two coats of paint later..... And also my new, light weight undercarriage, compared to a tea biscuit.
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #33 on: December 12, 2019, 08:22:15 PM »

Looking good with some paint. Still on a mission to shed more weight tho.
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #34 on: December 12, 2019, 08:38:25 PM »

A small disaster, just to spice up my project, heavy rain and strong winds blew water up under my shed roof ridge and right into my model. Water poured out when I lifted it up. Large areas of my sheeting had swollen and come away from the frames and gone a wavey shape. The areas that lifted are indicated by each pin. Bit of a panic but I seem to have saved it pretty well.
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #35 on: January 01, 2020, 08:45:31 PM »

Hi, some more photos of progress. I decided to build a bit of detail into the cockpit, only thing was that between the cockpit and windows, this added 20g to my airframe. Doesnt sound much but it put the weight over my max. So I did some lightening on the bits I could. I show a block of foam which weighs a gram. Also 3 g of balsa I removed. I took a lot of weight off the rear rotor pylon, mostly foam, some balsa. I got back my 20g and a bit more off the main airframe. I made a guage to tell how thin I was going with the foam. 1.5mm is my thinnest bit.
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #36 on: January 01, 2020, 08:47:31 PM »

Instrument panel and a side view.
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #37 on: January 01, 2020, 08:58:58 PM »

A photo of the insides of my hollowed out parts. My guage for thickness measurement and a mini longnose sander I made from meccano
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #38 on: January 02, 2020, 11:07:11 PM »

I had hopes of adding lots of detail on this model, I was hoping to have the loading ramp operated by a spare channel but weight restrictions mean I cant manage that anymore. I had also hoped to finish the cockpit with some seats and a carved foam pilot. My weight problem has resulted in extensive efforts to lose every spare gram. I managed to lose enough weight to get back within my target weight. Even as far as cutting out the sliding windows on the pilots doors,  saving a grand total of 0.25g. I also trimmed every fuselage rib, which was a challenge to do without breaking anything.  I used a scalpel blade, bound to a dowel with thread and superglued.. this gave me the reach to get in and carve away at the inside of my fuselage. I took about 3mm off each one.  I managed to halve the weight of the rear doors and decent weight reductions on other bits. Having lightened the sponsons during construction, I decided to try and get more weight out of this area, using my extended scalpel through the windows and my homemade long nose sander to try and tidy up the holes a  bit, I managed to get another gram or so out of my airframe.
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #39 on: January 03, 2020, 01:16:13 PM »

It flies! And with no shortage of power, my weight saving worked.  Video here   https://youtu.be/qtf1zaQAeaA

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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #40 on: January 03, 2020, 03:45:37 PM »

I had also planned to build scale rotors and gear them together but this would have been well outside my weight limit. I still fancy doing a set for display purposes. My pylons wouldnt take flying loads produced by freewheeling rotors anyway. I have enjoyed this project, it has posed a few problems that I eventually solved, but some that it was too late to rectify. The floor has a full length 1/4 balsa spine up the middle and a 1/8 spine either side. These could have been reduced in size, also the formers/bulkheads/ribs? could have been selected for lightness rather than a random selection from my scraps box. It is pretty strong though, I was  doing a tight turn at low height and caught a wheel, rolling it over, with no damage. I must say it performs better than I expected, it is loading the quadcopter quite a bit but it copes with no problems. Total outlay for this project was 10 sheets of 1/32 x 4 x 18 inch balsa (14 delivered) a selection from my scraps box (maybe 6 worth) and a wltoys v262 quadcopter (15 delivered, amazing value) These are good as standard (the ultimate collie excersising device)but are capable of carrying a decent load, especially once the epp bodyshell (85g) is taken off.
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #41 on: January 05, 2020, 02:47:54 PM »

If anyone fancies a wltoys v262, I would advise that the motors be run in before flying, this involves oiling the bushes and removing the props, I also removed the motor covers as these prevent cooling. The motors are run at first speed for about 10 seconds then allowed to cool, then 20 seconds and 30 seconds. After short time cooling I was giving it a bit more throttle in short bursts then building up to constant full throttle bursts of 10 seconds or so. The change in the motor noise as they bed in is noticeable. It only takes a total of 10 to 15 minutes to run them in and it will make the motors last longer. I found a website with lots on info about them and one thing that was repeated was importance of running the motors in.
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #42 on: January 11, 2020, 10:39:07 PM »

This project is essentially finished, I have to add markings of course, but dont think I can paint fine enought to do them justice, painting the foam neatly being hard as it isnt too smooth, and I cant afford the weight of filling it and repainting now. Tranfers, if they exist at 1/19 scale, would be ok on balsa bits but grainy foam, probably not. Anyway, after I discovered that weight was real tight, I decided to stop adding stuff to it,  I had planned to do seats, pilot, spare channel rear door opening, scale rotors geared together and even had hopes of lifting a cargo package slung underneath. Ah well. It was made to fly, so I am going to enjoy that as number one concern rather than scale colour scheme. I am still unsure about drawing on panel lines with a fine pen or not. It looks good enough for me without them from a flying point of view but I would still like to see them on there. I am worred it looks too obvious from a distance. I have a 0.3 mm pen, at 1/19 scale is just under 6mm wide seams on the full size. Mmm. Maybe not then. Could glue black hairs on I suppose, lol. Wheres the dog? Lol. The most obvious scale improvement would be a foam pilot and seat as you can see in the windows easily. I need to see how light a pilot/seat unit I can come up with.
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #43 on: January 12, 2020, 07:51:11 PM »

As my Sea Knight is mostly finished and I can return to do more work on it any time, I have already started my new project, another quadcopter powered helicopter, anybody got any idea what it is?
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TailUK

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #44 on: January 13, 2020, 09:13:52 AM »

Long round section tail boom! Could be a Russian Mil 8?
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #45 on: January 13, 2020, 09:40:10 AM »

Nope. I was going to do a cobra, but again, finding decent drawings was a problem. I was worried about rolling 1/32 balsa on a tight tube like this but it turned out not bad, I did the sheeting in two parts. Superglue to do the first bit of each and woodglue and pins to close it up. And well wetted balsa of course.
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #46 on: January 13, 2020, 03:02:53 PM »

Mil 8 looks nice right enough, need to add it to my list. Hoping to do a cobra as soon as I find decent drawings, at 1/19 scale to match the seaknight, it is about the same length. Also thought about doing skycrane at same scale, it comes out at  45 inches compared to 28 inch for seaknight, getting it within my weight limits would be a challenge tho. I built a skycrane for walkera 5#8 co ax helicopter, it flew but the rotor wash made the body wobble a bit. Sold to someone in germany. I have the video of it on my youtube channel. It ended up within my weight limit for the heli. The skycrane is pretty spindly so might manage 45 inch version within weight limit for my quad setup. The never ending build list. :-)
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #47 on: January 13, 2020, 05:55:26 PM »

Some amongst you may be wondering why I started building the tailboom first, main reason was that I wasnt that confident of managing to get 1/32 balsa round the thin end of the boom,which is 18mm diameter, without the balsa splitting. The rest of the helicopter body is even more challenging, with compound curves everywhere. So I picked the eaaier option. It also spurs me on to do the rest of the working out on how I am going to build the fuselage. I have got decent drawings this time and a reasonable bodyshell to copy from a cheap co ax heli, it ate one of its motors after about 10mins of first flying it, after buying 2 more sets of motors, I found out that 10mins is actually the longest I got from a motor! Ah well the bodyshell is good, my balsa one is going to be 3 times the size at 3 feet, so scaling up is easy. Building as light as I can, I hope to have the weight of the bare bodyshell with no motors, receiver or battery around the 200g mark. A bit of a challenge but I have managed to build the tailboom, horizontal stabilisers and fin at 20g. I have still to refine the sanding, which will take a small amount off this, then painting will put more on. Its promising. Undercarriage and glazing will add a fair bit, more paint. I need to keep it really light from the start as there are so many bits I cant lose weight on, I already made my first mistake with the tailboom, its formers are 2 layers of 1/32 glued together with grain running 90 degrees to each other forming superlight ply that you can cut into without it flaking off. There are seven formers, I was going to cut lightening holes in the inside 5, leaving end ones solid for gluing........I forgot, it was only after I had cut all my slots and glued the stringers in, ready for sheeting, but much too late for holes. Ah well. I am trying to design my fuselage as light as possible to compensate a bit for my error, I hope to use 1/32 balsa for as much of the structure as I possibly can, while being strong enough for a heavy landing.
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Andy M

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #48 on: January 16, 2020, 02:28:12 PM »

Here is my tailboom assembled. Anyone know what it is yet?
I have cut out all my body formers/bulkheads/frames, I have just to sand the edges to their finished shape and cut slots for stringers (longerons?) I have still to work out some of the parts to join all these together accurately, I am making it up as I go along so I will get these figured out soon.
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KitS

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Re: Boeing Vertol CH-46 Sea Knight - My helicopter build
« Reply #49 on: January 16, 2020, 04:20:42 PM »

Looks like one of the umpteen Bell Jet Ranger derivatives.
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Regards
Kit
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