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Author Topic: Andy's - Bell 206 JetRanger build.  (Read 4241 times)

warspite

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Re: Andy's - Bell 206 JetRanger build.
« Reply #50 on: February 04, 2020, 11:52:53 am »

You never know - someone may come out with a full scale version of this some day, though it is an old concept, since if you watch the classic series thunderbirds they had jet versions (in the military walker episode).
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #51 on: February 04, 2020, 05:49:17 pm »

Here is some video of it flying, and the result of a slight crash, the tailboom was only damage, fixed in 2 minutes, just to wait on glue drying
Video here.   https://youtu.be/5qzB2LgUZjU
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #52 on: February 04, 2020, 05:58:14 pm »

Thunderbirds helijet. Looks perfect for quad powering, anyone else fancy doing one? I already have a list of projects using these  quadcopters.
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #53 on: February 05, 2020, 02:54:34 pm »

If you watched the video of the jetranger flying, twice it tips back and looks like its going to reverse into the ground, I saved it both times or it would have. I have been wondering what could cause this, I wondered if it was pendulum action of tail boom as I pulled back slightly to slow down. It is slightly tail heavy now I have the cockpit down to 30g. I wondered if it was because the horizontal fins are entering the downwash from rear rotors and being forced down. I flew it after I snapped the tailboom off, actually looked pretty good, never did the tail slide thing either. I will try it without the fins, they just slide onto a 1/16 balsa joiner, I have snapped 3 of them already, none from flying, all hanger rash. My tail rotor doesn't seem to want to freewheel like I thought it would, I did think about motorising it off my spare channel, but I never made provision for that when I was building it. Looks good when it's parked. I also wondered if my quad rotors are too close fore and aft, the Seaknight has same width over rotors but lots more length. Seaknight is 17. 5 inches, jetranger is only 9. Its a short pitching moment compared to the Seaknight. I suppose everything has its own traits. Still well happy with it, even with its funny habits, I am still amazed by how light it feels, the last jetranger I had was Morley mx ranger, weighing in at a hefty 8lbs plus. It needed a 45 engine to get airborne, mine is 3/4 the size and gets airborne on four small motors and a 7.4v 850mah battery! For about same length of time. In the living room.
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #54 on: February 08, 2020, 02:07:59 pm »

Just to prove it does fly in our living room. Not getting too adventurous though. Definitely no shortage of power.
https://youtu.be/N9UfYD933PE
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #55 on: February 08, 2020, 02:10:50 pm »

Jetranger has had a 2nd coat of paint on the fuselage, wishing I hadn't done my markings in pen. A lot of my working lines are still visible, but getting more faint. Still got to get another coat on the nose section. I flew the jetranger on Thursday, taking care to make the transition from flying forward to slowing down as smoothly as I could, I managed to avoid provoking the dreaded tail slide. I can tell the fore and aft control is increased due to the quad power units being closer together. It also has less leverage to recover from forward and back movements especially with the long pendulum of the tailboom. Now that I know how to avoid it, should be fine from now on. Hopefully.
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #56 on: February 10, 2020, 05:53:56 pm »

Having decided that at least part of the handling quirks are down to the fact its a bit tail heavy, even though the actual boom and fins are around 1 ounce, the tail rotor added a bit, I forgot to weigh it but its more weight really far back. When I flew it with wooden mould on front, it crept forward, now with my lightweight nose, it more than creeps backwards. I think I am going to add some cockpit detailing to put some weight up front, I have more than enough power left. It will be pretty basic, I am going to fix the perspective of this photo on photoshop, get it printed,stuck to a 1/32 console and hey presto, a nice light instrument panel. Maybe some front seats too. Nice foam carving exercise. If it's still not heavy enough to balance the tail, I was thinking I might have to move the battery forward into where the rotor comes out of on full size.
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #57 on: February 11, 2020, 11:34:12 am »

I made a start on the cockpit detailing, I hadn't noticed the big pillar just behind the front seats until I started researching the jet ranger, I have even been in one twice, there is also a a sort of half bulkhead that the backs of the seats attach to. I have already made and fitted the pillar, made the bulkhead and got foam blanks cut out for my seats. I was going to do them from balsa but decided hollow non load bearing foam will be light enough. I am leaving the bulkhead and seats unglued until I am sure I don't need in the back seat area, for pillar painting. I am probably only going to do front seats. I also made a start on my rotor blades, 8g for the skins, before I started adding bits. I have 1/32 bottom skin with 1/8 x 3/16 glued along front edge, 1/16 tiny ribs blended to chamfered lower skin trailing edge. This has been sanded to 0.4mm (1/64) approx. Also added were crossgrain 1/8 softish sheet tips and 1/8 hard balsa root block. The top skins have been glued on with pva. The top sheeting trailing edge overlaps bottom one bringing thickness to 3/32.   Pinned to the board with 100 pins, no idea how strong they will be once they are dry, I might end up having to remove them for flight, will give it a try anyway once they are finished.
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #58 on: February 11, 2020, 08:41:41 pm »

Bulkhead sat in position against pillar, foam seat blanks ready for carving and a pair of blade blanks, still to be sanded etc. I need to make up a rotor head as well.
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #59 on: February 12, 2020, 04:04:51 pm »

8.2g blade blank sanded down to 7.6g, I thought they were both the same weight as they were made from 2 balsa sheets the same weight. Anyway, the other one is 6.2g! So I need to add 1.5 g to it. Or I should really wait till I have made the rotor head and balance it then, this will probably be 1.5g of solder and a hole drilled up the end of the blade. I haven't weighed out the solder to see how long it will be. The seats are 3g for the pair unshaped, bulkhead is 1g, I might cut holes in it behind the seats. I reckon the pillar is another gram. Not started on instrument panel yet. Rotor head will add a fair bit. I am considering sacrificing my walker a 5#8 coaxial helicopter to provide my rotor shaft. It had a long service, well over 1000 flights. I tried it about 6 months ago and it wasn't flying right, kept flipping back and to the side. So it's probably going to get stripped. The jet ranger needs a rotor, even if it only gets used for display purposes, I will try it in the air if I get it light enough, but even if I can get it turning on the ground, I will be well happy. It will be weight in front of my quad rotor centre, just don't know how much yet. Blades will be 15+ as they aren't painted yet. So it's goodnight for the walkera. Its rotor shaft is going to be perfect, just need to add some structure to my airframe to hold it firmly. Will get into some dismantling  later. Photos show how thin my outer skins are and a few pics with the sea Knight.
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Martin [Admin]

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Re: Andy's - Bell 206 JetRanger build.
« Reply #60 on: February 12, 2020, 05:16:31 pm »



Found this on Facebook Andy!   {-)



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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #61 on: February 12, 2020, 05:25:33 pm »

That's brilliant. It is definitely recognisable as a piasecki h21 flying banana. It probably weighs more than my jet ranger.
Here is a full battery flight in my living room when the wife popped out. I bump into the dogs bed at one point. Also close enough to furniture to have caught the rotors if it had been a normal helicopter..... I love it. Hopefully get a chance to work on interior and rotor head later on.
Nearly 6 minute flight on 7.4v 850mah battery here. https://youtu.be/CK0xhH-EZNw
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #62 on: February 12, 2020, 11:25:27 pm »

Having been kindly given a bigger set of ditigal scales by my mum, I have now weighed the jetanger accurately. All up ready to fly, including standard 7.4v 850 mah battery at 46g it weighs 365g! Quad parts and battery add up to 167g. This means my airframe weighs 198g, with skids, cockpit assembly and fake tail rotor. Can't remember how much those bits are exactly, think it was 30g each for skids and cockpit and under 5 for tail rotor. Puts my actual balsa fuselage in about the 135g mark. About 45g per foot. It is so much lighter than it looks. Really enjoying flying it and still having projects to do on it, not many helicopters you can fly before you have finished building the main rotor....... Photo shows my almost finished rotor blades and the tool I used to cut 1/64 ply reinforcement discs I am gluing to my blades. Hope to start on rotor head drawing later. The drumstick is for poking the discs out of my cutter.
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #63 on: February 12, 2020, 11:27:58 pm »

I forgot to say that for cutting the discs, I used the cutter in a cordless drill, gives a nicer cut.
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #64 on: February 13, 2020, 10:10:48 am »

Here is the shaft I am going to use, stripped from walker 5#8. I don't know if I am going to use the other bits until I start properly on the rotor head. It is ballraced, so it's got the best chance of actually spinning.
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #65 on: February 13, 2020, 09:48:20 pm »

Blades finish sanded, spray painted matt black. Black paint had soaked through the wood, under the tape. Tape was rubbed down but wood is really absorbent. First coat of yellow on tips. Need to get stuck into doing my rotor head soon.
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #66 on: February 14, 2020, 12:38:56 pm »

Another coat of yellow on the tips helps, maybe one more to do. Rotorhead and blades are nearly complete, quite heavy at 30g but it's quite a big structure. Rotorhead is 1/4 hard balsa with 1/16 ply top and bottom, balsa details. I had to add 1.3g steel rod in the tip of the lighter blade. Managed to break through the surface when I was drilling the hole for it....... I am a bit worried about running  the rotor system on the heli, don't want to slice my tailboom off. The blades are only 8g each but still a bit of momentum once you spin them. I will proceed cautiously, flying with it will be interesting, don't think it would handle forward flight too well, a huge mix of aerodynamic forces on a superlight structure. If it works for hovering I will be happy. If it even just spins in the downdraught when it's on the ground , that would do as well. I need to open up my top sheeting for the rotor mast and see what I can attach my structure to. It's all pretty light up there but there are bulkheads I can attach to.
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #67 on: February 14, 2020, 04:23:19 pm »

Here is the rotorhead with detailing and a bit of paint. Looks good enough for my purposes and I didn't want to add any more weight. I still have control rods and base to add but the rotor system is within the 50g that I have available, might even manage enough leftover to carry my seats, bulkhead and my planned instrument panel, which I haven't got round to yet. Cutting out the areas behind the seats on the bulkhead took 0.3g off. Tiny amounts, but worth removing it. I am also going to hollow the back and bottom of the seats. Be interesting to see how much they come out at. They were 3g for the pair, unshaped. They have been shaped and a coat of paint added, one more to go. I am hoping they will still be around 3g painted and hollowed.Last photos show the magnet and kebab stick breakaway system on my tail fin. It's been knocked off about 50 times so far, so it's doing its job. The horizontal stabilisers have a 1/16 soft balsa joiner, which breaks easily, none when I have been flying/crashing but I have snapped 3 of them in my workshop. I flew it outside yesterday for 4 full battery flights, it still did the tailslide thing, a few times hitting the ground quite heavily, but no damage. I am getting better at avoiding the tailslide but I still get adventurous. Had 2 living room flights today, narrowly missing wife's vase of flowers while practising a table landing. It is very stable apart from me having to hold a bit of forward on all the time. Extremely slow movements are possible (even if they are not visible in my videos, lol) Once I get my balance point forward a bit it should be perfect. Loving it so far, just wish my living room was bit bigger! Ha ha.
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #68 on: February 14, 2020, 08:05:30 pm »

Rotor system freewheel test video here https://youtu.be/7y8xNtBdJ20
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #69 on: February 15, 2020, 02:40:03 pm »

Here are my seats, weight over 2g each so a bit of hollowing on the back and under seat. 1.7g each, so bit more hollowing gets the pair down to under. 3.14g good enough for me, nearly broke through a couple of times so that's enough. Last photo is my rotor system weighing in at over 30g. Only got to attach it now. And make sure it is removable.
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #70 on: February 19, 2020, 11:46:54 pm »

I was quite impressed with the way the rotor freewheels,  I am pretty sure it will spin with the air getting sucked down towards the quad props. I always hope for the best, but can cope with just having it for display if it doesnt work or looks like its going to slice my tailboom off. I hope to get that mounted over the weekend, I dont think I will test it indoors though, especially now I am used to flying it without it, I will need to stay a bit further away from things now
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #71 on: February 21, 2020, 05:20:56 pm »

I couldnt resist, and in the interests of structural testing of my rotor system in regards to it coming apart and detroying my jetranger, I have now tested my rotor system in a cordless drill, to rpms far in excess of what I expect it to be freewheeling at. I only went to 3/4 throttle on speed 2 but it was fast enough for one hand. Pretty sure it would have taken the rest. I have to say that my main rotor shaft is just a really tight fit in the rotor head, another reason to be backing off when I did, according to drill, its full speed is 1400rpm. I was probably at about 1000, with something that weighs 30 odd grams, quite amazed it held up,    the right material in the right places. I had thought my fake balance weights on top might have flown off but they stayed put. Having now tested it, I need to see if I can actually fit it. I have restricted my access a bit inside by adding the central pillar. I might have to cut that back out to let me inside the fuselage to add structure for bottom end of the rotor bearing block. I should manage the top bit from outside, still have to make up a set of dummy control rods and the gaiter and link thing that goes on shaft just inside rotor opening. I just keep getting a nagging thought in the back of my head, saying, why are you adding the possibility of a tailboom strike to a helicopter that doesnt have that possibility. I dont know really, I just want to see it flying with a proper rotor disc showing its yellow tips, even if it just trundles round, will be good for some photos. Next bit of testing I am really looking forward to is trying it on the fuselage with the quad motors sucking air through it, I might try a temporary setup to see if it will turn, before I cut holes in my nice fuselage. I may just have two cross bits of 1/8 balsa with holes if the rotor system is just for static use.
Cordless drill test video here.  https://youtu.be/w-z4pF8FZgI
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #72 on: February 21, 2020, 06:35:10 pm »

Well that has decided that for me, I have clamped rotor bearing to bit of wood and taped a quadcopter underneath, as it would be on jetranger. Ran quadcopter up to full speed, not a sausage, the rotor never moved. I tried helping it by spinning it but it just slowed down. Ah well, static display it is then. Couple of bits of balsa to hold it. I was worried about it chopping my tail off anyway.
 Ok so that doesnt figure into my flying weight anymore, so my cockpit detailing can be bit heavier/more detailed. Might even manage a pilot, foam, rough hewn with angular, granular kind of appearance. Lol.
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warspite

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Re: Andy's - Bell 206 JetRanger build.
« Reply #73 on: February 22, 2020, 08:57:56 am »

Noticed there is so angle of attack on the blades, so they wont rotate with the flow of air until it is in the air and dips forward or back, the angle would also have to be quite big as well, as a little wont have enough of an effect. just my thought  :D
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Andy M

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Re: Andy's - Bell 206 JetRanger build.
« Reply #74 on: February 22, 2020, 12:43:21 pm »

There is a small amount, around 3 degrees.I have built autogyros in the past, so I know 3 degrees isnt much, I did hope that all the downward airflow would do the trick. To be honest, I was worried about carrying it about on my heli due to aerodynamic forces through my fairly flimsy rotor system. I will finish it for static display, its a bit late to change blade angle now anyway. I will finish off my cockpit and that should help with the tail heaviness. Apart from that, I think I have ended up with a nice model that turned out a bit lighter than I had hoped.
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