tjmackey

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a pic of my homebuilt 1/6scale lama. Its powered by a 25cc talon hedge trimmer run on methanol.

BarracudaHockey

My Feedback: (11)

Cool.

Going to turn the pool toys into working floats?

Elgreco3

LOL...... like the toys on the floor and the video on the TV ....

tjmackey

Yea the kids can be messy, and as for the tv, It was just by chance that the add was on when i took the pic, Is anyone else out there building helis from scratch like this?? if so would be very interested to see, I will soon be adding a build on a turbine Lama powered by a funsonic heliturbine if you guys are interested just have to wait for the turbine to show up

tjmackey

more pics of the lama in the process[img][/img]

tjmackey

more pics[img][/img]

tjmackey

Has anyone had anything to do with the mw54 heli turbine from wren? The specs state 8 hp however we are unable to confirm the continuous rated hp for these engines, we have sent many emails to perth rc and received no information. Can anyone help with this problem[]

mrblonde

Damn thats impressive, how much of that is built from scratch?

tjmackey

Well the blades are off the shelf, as is the engine, tail gearbox and swash plate, all the rest is built. The rotor head is the second of a prototype that me and my old man built, the prototype took 7 years to develope, it has lead lag and flapping hinges, All on the same axis. This allows the head to operate without the need for gyros or any type of stability control

mrblonde

I could only imagine something like that at the moment. I would be afraid to fly it when completed.

tjmackey

Yea, there is still some work to go. Im currently building some scale features such as the cocpit interior and the dummy gas turbine, however i will be posting a build of a turbine powered lama very soon, the turbine had to come from wren ans the funsonic heliturbine is still in progress. Should be reciveing the turbine by next week

tjmackey

We now have the turbine, now just have to build the heli

wiz310

Ah, good to see. I am currently doing the same with a 3.5M B47G3. I was inspired by the Spanish chappy that did it in 3M.
I will also be doing a build thread when I get a bit further into it. Gotta love the Talon gear. $100 for a whole whipper snipper, and plenty of other tools they make that can be robbed for stuff like clutches and stuff.

tjmackey

wiz310, would love to hear more about your bell, have you done some tests on your rotor system to calculate lift hp? and what would be the all up wieght? I imagine you would be running 700-800rpm on the main rotor max. Thats a massive project, keep me posted

wiz310

will do. Have done some maths, and will be running the RRPM around 850. The weight is a pure guessing exercise at this point. I am going to try several things to reduce weight, like make the tail truss from Aluminium instead of Stainless, Etc. its all a drawing board exercise at the moment, while I research a few things. but I will do a build thread when I get to it.

tjmackey

Hi, wiz310, i would strongly suggest you stick with the stainless brazed boom, as tig welding aluminium with small sized tube will be very difficult and require a larger wall thickness, I used an aluminium boom on my project, bolted together, and the weight was more than what i can make a stainless boom, Using hypo grade stainless brazed with silver in my opinion, will give you the best result. I have done some tests on this and I will be changing my boom to stainless hypo tubing in the future as i can make the assembly for about 2/3 of the wieght and it will be stronger. Stainless also suffers less from fatigue

wiz310

Thanks for the advice............Buuut, I'm still going to give the Aluminium a go. I can TIG weld fine, and have no problems with small stuff, although the tube on a 3M heli is pretty big. I will use the thick walled stuff, for both strength and rigidity. I don't thing Fatigue will really be an issue (I hope its not, as both my full scale aircraft are made from it ), but if worse comes to worse, I'll adopt the Stainless and silver solder method. Most of my frame work, cross tubes, skid mount tubes and skids will all be made from Aluminium as well.......... along with several of the head and tail parts. Its so easy to work with and light as well as being pretty strong if the right grade is used.
Cheers, Wiz.

tjmackey

On the larger scale you are building the ally is worth ago, I didn't think about the size difference[] ally used on my 1/6th scale lama would be imposible to tig due to the small sizes, however on your model this maybe sucessfull, the only reason I recomended stainless was the weight and the ease of construction on a model of my size, however, the 3.6m beast you are thinking about is another concept.

underthefloor

Are the blade grips padded to allow the blades to flap around the bolt that holds them to the grip?

The build looks really impressive.

tjmackey

underthefloor, no the bade grips are not, the lead lag and flapping all happens in the hub and has soft dampers to act as bump stops. The head has the full freedom to lead, lag and flap indipendantly, also the blades feather as they flap, so as the blade rises pitch is reduced, and when it is low pitch is increased. This helps to govern the head and appears to smooth out the flight charactoristics.

RHYNO

Tjmacket I am embarking down the same path at the moment but I am going 1/5 scale so if I get lazy, I can use Hirobo bits I don't know if I'm going to use chrome molly or stainless steel,but I will be using easyflo to stick it all together....I'm using drawings from full size machine,and drawing it all up in 3D at the moment. I also will be building my own turbine to go with it as well.

Rhyno

tjmackey

RHYNO, sounds good, im building a turbine engine also, all ready have the wren mw44 turboprop engine for another project, but i have already built a turbine myself and am currently making refinements of the design to build another that will produce the shaft hp for a heli. You say you are using full size drawings of the lama? Is it possible you could send me a copy? These would be very helpfull for the next project

RHYNO

Sorry I meant I am making drawings off photos and measurements from a full size heli that I have at my disposal and drawing it up in solid works,but I could send you the drawings I make...no guarantee they are any good of course....I am thinking of using a GT-2000 and putting a wren 2 stage gearbox in the end of it. I am also in favour of using toothed belts and pulleys as they are quiet,off-the-shelf,and don't have the set up issues that gears have.What do you think?

Rhyno

tjmackey

RHYNO, I Think toothed belts are fine, and resonably efficiant. Thats what is going to be used on the mw44 turboprop engine to transmit the power down to the main rotor gearbox for the current Lama project as long as they are periodically checked for wear in my opinion they are fine.
Also in regards to the turbine, if you are building it youll find the power takeoff side of things is not as difficult as the gas producer is to build, if you build the gas producer you might as well build the power takeoff side as well. Have you seen the picture of the sectioned mw54? Definatley something worth a look

wiz310

Just a small tip for you guys, although your probably aware of it anyway. I was researching my LHS for parts for my Bell, and found heaps of buggy parts are perfect for the job. Really big ball links and shafts, gears Etc. I found quite a lot of parts were perfect for the job without any form of alteration at all. even some of the big steering servos were well suited for the project. I was able to build a tail box from some existing spur gears ,bearings and shafts, and use universal joints from the buggy axles for the tail drive system.
They all fitted the job like they were manufactured for this project.
Cheers, Wiz.