450 Rooivalk project

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Theuns v V
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450 Rooivalk project

Unread post by Theuns v V » Sat Jul 11, 2015 8:26 am

I was very fortunate to get the plug for a 450 size Rooivalk from OB_Scorpio.
He unfortionately will not be completing the project so I will try my absolute best to do it justice.

It is the plug for the molds I need to still make.

There are some interesting aspects of this heli's engineering I will have to fgure out as I go allong.
The tail offset will have to be sourced, the mounds for the undercart also will be interesting to get right.
I also need to see how the weird anglke that the real heli sits to the ground will affect the model's take off handling....

This will be an exersize in very light weight molding tecniques for the limited 450 performance. Te rooivalk also have allot of flat straight sides that will take some thinking to mold stiff enough yet not add the pounds, maybe some "sandwiching" will work. Only after the molds are made and the first layups come out will I be able to see [-o<

Pix to follow.

T
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Re: 450 Rooivalk project

Unread post by Peter Connan » Sat Jul 11, 2015 12:55 pm

Ok, where's my popcorn?
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Theuns v V
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Re: 450 Rooivalk project

Unread post by Theuns v V » Sat Jul 11, 2015 4:53 pm

Basic plug for the molds, I will have to make the jet exhaust as a seperate sections to be able to release from the mold.
I will also have to make a large removable section under the front canopy to be able to slide the mechanics into the fuse.

I have seen some fuselages made from a vacformed plastic PVC,, I will look into that otherwize make them from epoxyglass.
Should look damn awsome with a 4 blade head....especially in the white UN coclor :)

T
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Re: 450 Rooivalk project

Unread post by chrisvis » Fri Jul 17, 2015 2:30 pm

Hi theuns ek het heli en 4 blade head. Wag in spanning.
Fly it like you stole it...
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Theuns v V
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Re: 450 Rooivalk project

Unread post by Theuns v V » Fri Jul 17, 2015 6:33 pm

Nie so spanningsvol soos ek nie.....ek moet die plug aanpas om 'n mold van te kan maak :lol:
Die vertikale deel van die stert fin is effe smal om die ratkas en boom te kan vat soos dit is. Sal ekke moet verander, anders is die romp BAIE na aan skaal =D>
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Re: 450 Rooivalk project

Unread post by ruan7 » Sat Jul 18, 2015 8:09 am

PM sent
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Theuns v V
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Re: 450 Rooivalk project

Unread post by Theuns v V » Sat Jul 18, 2015 8:16 am

Thanx Ruan, replied :)
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Theuns v V
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Re: 450 Rooivalk project

Unread post by Theuns v V » Wed Jul 22, 2015 5:22 pm

Anyone maybe have the dimentions of an offset gearbox that fit the 450's tailboom? [-o< [-o<

I need to design the mold so that one can have only a small removable section on the tail to fit the offset into the fuse without having to "go stupid" with complexity
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Theuns v V
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Re: 450 Rooivalk project

Unread post by Theuns v V » Mon Jul 27, 2015 7:20 pm

As soon as I get the sizes of the offset box I can start making the basic mold.

T
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Theuns v V
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Re: 450 Rooivalk project

Unread post by Theuns v V » Tue Jul 28, 2015 2:37 pm

Damn, I ran into a problem with this bukld. Something about the extremely narrow profile of the rooivalk has been bothering me. I checked and the main gear on the 450's mechanics is about 5 mm to wide to fit inside the fuse. I will have to put a 10mm spacer inbetween the 2 halves to compensate for this.

Lucky I did not make the mold yet.

T
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Re: 450 Rooivalk project

Unread post by OB_Scorpio » Tue Jul 28, 2015 7:46 pm

Just check as far as I can remember I made the side wings/ rocket carriers a bit thicker than scale to compensate space for the main gear. Also think about using a smaller main gear as for scale you want to bring rotor speed down and maybe play with pinion gear to get the speed you want?
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Theuns v V
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Re: 450 Rooivalk project

Unread post by Theuns v V » Tue Jul 28, 2015 7:56 pm

Nah the "playing with gears" is way to complex for me... :lol:
I wanted to make the mold so that any "standard" 450 will fit inside. I have already made the shim that increaces the inner diameter at the pylon's position by about 10mm.

Granted it is not true scale, but I think it still looks OK....besides, there are NO other Rooivalk to be bought :wink:

I also had to modify the plug a little inorder to make it "friendly" as a glass mold, the pylons were removed and the last section of the exhausts aswell, otherwize they will not come out of the mold.
These can be glued on to the completed fuse once joined.

I will now have to smooth out the shim area and make it ready to pull the mold of it.

How did you think of mouding the main undercart gear to the fuse?? I have not worked that one out yet, was thinking of using piano wire bent and secured to the inside of the fuse.

Still cant get the dimentions of the tail offset box to make sure it will fit the tail :(

T
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Re: 450 Rooivalk project

Unread post by OB_Scorpio » Tue Jul 28, 2015 8:00 pm

http://www.helifreak.com/showthread.php?t=349611

http://www.helifreak.com/showthread.php?t=574013

Remeber that if you want to go hard core scale all internals would need some modification or custom building, and that said if you going for just a scale look some things could be sacraficed for plug and play build. Look at the second link the pic of the Apache where the main gear is exposed and maybe even some tail detail lost.
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Re: 450 Rooivalk project

Unread post by Lomcevak » Tue Jul 28, 2015 8:15 pm

have you looked at the thunder tigre mini titan tail mechanics used on the cobra body?
should fit this heli and add to scale look!
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Theuns v V
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Re: 450 Rooivalk project

Unread post by Theuns v V » Wed Jul 29, 2015 6:12 am

I totally agree that "real scale" would need some mods, but having flown since '86 incl some scale I have come to a point where a nice looking model that represents the basic look of whatever I am modling (and flies well) is what I am after.

Because I want to make a mold of it, there are also some things that need to be modified otherwize the plug would never get out of the mold undamaged.

The shim I added would be picked up by the "purists" but I am still convinced that it looks like a rooivalk and I am sure it will do justice to OBScorpio's original intentions :)

I now need to blend in and fill the joint line and smooth every thing out for mold making.

T

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