Hoss Helicopter - RC Groups
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This thread is privately moderated by JamesBC, who may elect to delete unwanted replies.
Aug 07, 2011, 03:07 PM
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Hoss Helicopter

If anyone is still flying a Hoss Heli 450, would love to hear from you.

In the spring a local flier put up his HOSS heli for sale. I was intrigued with it, and decided to buy it from him. Now for those who donít know what a HOSS heli is, it was designed, and a few kits where sold. It was or is a full belt drive heli, I am posting some pictures of the one I bought, since I didnít think about taking pictures of it.

I contacted the gentleman that designed and sold the kits in attempt to get some info on it. His reply was polite, but said he had spent a lot of time and money in R & D and even though he didnít intent to make any more kits, was not willing to offer any info. Which is fair enough, although since he didnít want to make more kits whatís the point in not sharing info.

I took the one I bought and hovered it couple of times and was intrigued with how quiet it was. One of the things I did noticed was the tail rotor was not built to turn without motor power. Main shaft had a one-way bearing so it would turn freely but the tail drive would not. Now I am not good enough to try it, but would think that in auto rotation not having tail control would make setting down without power rather difficult.

Being so intrigued, I took my Hoss all apart, and decided to start making up my own full belt drive heli. At first my thought was to just reverse engineer the Hoss I had, but as I begin to play around with the design decided to change more of it.
Last edited by JamesBC; Aug 12, 2011 at 08:33 PM.
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Aug 07, 2011, 04:22 PM
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Now I really didnít want to redesign the main gear or even the tail gear for that matter, so went to SDP and checked all their gears. I found and ordered up plastic gear for main, along with a pinion and belt. I simply used the tooth count from my Hoss as the best count to start with. I did order up a larger main gear, which might get tried out later. It only took a couple of minutes on a lathe to turn the plastic gear down so I could mount a KDS one-way bearing on it. I did read where the Hoss was heavier than most 450 heli so just to check I weighted the plastic main gear and the Hoss metal main gear. The plastic one weights 20g and metal one 30g. At this point I am really not concerned about weight, will worry about that when I am much further along. Pictures show the main gear, along with the KDS belt tail gear which I will be using for now.

Also not wanting to have to worry about servo mounting and such, decided to incorporate the bearing blocks from my PRO which has all 3 cycle servos mounted to them.
Aug 08, 2011, 02:16 AM
Physics hate's my ideas
GreenAce92's Avatar
Does the tail rotor run off the same belt? That wouldn't make sense to me... or is there another gear attached to the main shaft just like other helicopters?
Aug 08, 2011, 10:57 AM
Registered User
On the Hoss that I have, the pulley for tail is bolted to the main pulley. Hence when the motor stops, the main pulley stops. Like other heli's the main shaft will turn due to the one-way bearing.

On the one I am building, the tail pulley is like other heli's in both it and the main shaft will turn even if the motor is stopped.

The one picture shows the large main pulley which is black and the tail pulley which is white, the white pulley is a KDS pulley which is what they use in their 450's. One of which I fly.
Aug 08, 2011, 01:20 PM
Physics hate's my ideas
GreenAce92's Avatar
Fascinating, you're just modding this by yourself?

Good luck on the "restoration" ?
Aug 11, 2011, 12:35 PM
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Well work goes slow, I have used some plexy to cut out the top frame only to test how things fit. Also made up some blocks to hold the tail boom but of course the bolts I need for that are on order. Also need some 2mm taps, so need to order those.

I tried to use the motor mount out of my pro heli but its not going to work due to the pinon being larger at the base. The pinon hits the allen's that hold the motor. So will have to cut out a new motor mount using the wider bolt pattern on the motor. Doing that I can move the pinon down, then can move the motor mount holes up on the side frame. When I am satisfied with the top frame, will cut it out of T6 for the first shot. Then will have to work on the bottom frame.

I am using the belt pulley from KDS for the tail, but also ordered up the parts for the Black Angel Heli which unlike the KDS, has the tail pulley on top of the main gear.

GreenAce92, "restoration, modding" by myself yes, but not sure those words work since I have pretty much changed most things on the Hoss. Its in the parts bin in pieces.
Aug 11, 2011, 12:37 PM
Physics hate's my ideas
GreenAce92's Avatar
I do apologize my vocabulary sucks, I haven't been reading

This is incredible work, do you have your own machine? CNC and such?

How do you cut the parts so precisely? Do you use a caliper to accurately measure distances such as the belt from the motor to the main pulley?
Aug 11, 2011, 01:12 PM
Registered User
Originally Posted by GreenAce92
I do apologize my vocabulary sucks, I haven't been reading

This is incredible work, do you have your own machine? CNC and such?

How do you cut the parts so precisely? Do you use a caliper to accurately measure distances such as the belt from the motor to the main pulley?
I have a small Sherline Mill that I use. The motor to main pulley was a close guess, but the motor can move back and forth since the mounting holes for it are slotted. That mount is the one from a 450 pro, as I said do have to make one with the slots moved further out so the pinon has room to move down. That of course will mean I have to move the motor mount up to align with the main pulley. Will proably recut the sides in plexy again just to check fit again. Its really easy to cut the plexy, T6 won't be so easy plus plexy is free for me and T6 will need to buy.

And to answer your main question, I have not one, but two digital calipers on my work bench. (that way spend less time looking for the one I just had in my hand!)

thanks for your comments

Aug 11, 2011, 01:57 PM
Physics hate's my ideas
GreenAce92's Avatar
That's great! I wish you haste in completion of your project! (there how's that)
Aug 21, 2011, 04:28 PM
Registered User
Well work goes slow, managed to get the tap I needed to mount the tail belt guides. I had an extra set of ones from my KDS, they are the plastic ones runing on a brass insert. I had changed mine over to metal pulley's runing on bearings. The plastic ones will do for now in testing and setting up. Its about time to get some T6 and cut the upper frames, things all fit for now. The only change I will make before cutting the T6 is to move the tail up a small amount to better align with the belt pulley.

Then it is on to making up the bottom frame with mounting for landing gear and mounting the ESC, ECT ECT.

Belt Drive 2.wmv (0 min 48 sec)
Sep 13, 2011, 09:11 PM
Registered User
So work goes ahead slowly. I found some T6 Aluminum .050 to cut the frame sides out of. Discovered one problem in the top frame that required a redraw and recut of the top frame sides.

Everything seems to be working now, next step is to order some 500 size landing gear for it. Also will need to decide on how to mount the bottom plate and plate for the gyro to sit on. Been thinking of using the Panel Glue that body shops use to install new panels in some of the newer cars, if its strong enough for that might be just right for mounting plates to hold gyro and ESC plus save a little weight.

Anyway some pic's of the T-6 Frame.
Last edited by JamesBC; Sep 14, 2011 at 12:21 AM.
Sep 26, 2011, 01:06 PM
Registered User
Not sure if anyone is following this, but have done more work on it. I mounted the plate for the battery to sit on. Used 3 counter sunk screws to hold it in place. For the gyro mount, I used some panel glue to attach the plate to the cross pieces, after it had dried, tried to pull it off, it sticks good so not really worried about it coming off.

It was only after I had started to put on the tail boom brace that I had a small problem, getting the braces to fit without to much bend. Fixed that by making the small extra link as the picture shows. The next time I cut the lower frames going to add that part to the frame so its all one piece.

I have cut what I think will work for the bottom bearing carrier, should get that done soon and fitting landing struts. I have ordered 500 size since that is what is on my other 2 450 that I fly.

So for now not much, but getting closer to a test flight. Due have to assembly the KDS head I have. It was in a slight accident and just never tore it down to replace the feather shaft. It will be used for a few test flights on this one. Maybe go to FBL if it handless ok.
Feb 28, 2012, 05:58 PM
Registered User
Well it takes to the air, finially. Now need to lower head speed, get rid of the flybar and try again.

Belt Heli2.wmv (1 min 19 sec)

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