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Got Jet Fuel? Turbine Helicopters > Turbine scale pipe

optikaman

Veteran - Location: EnglishTown N.J. -

Well i decided to make my own pipe for the Hughes 500, I dismanteled a straight two walled pipe from a MB339 kit for the material. This is my first exposure with a sopt welder and i think it came out ok.

I still have to weld on some mounting tabs and test the pipe, i hope that the deflectors at the exit help with diverting enough thrust to keep the heli some what level during hovering. testing will be done on the jetcopter next weekend. It took me 3 1/2 hrs to make the pipe and i only lost a few ounces of blood from few cuts on my hands, how are your hands doing Wojtek?

Alan...

08-17-2003 Over year old.

michaelmillikin
Senior Heliman
Location: Granite Falls NC USA

optikaman

where did you purchase the fuse from??

thanx looks like great quality ..

08-17-2003 Over year old.

optikaman
Veteran
Location: EnglishTown N.J.

It is a Vario giant Hughes 500 , the fuse is 6 ft long and stands 27 inches high. you can get one from vario usa and from Challenger hobbies.

vario usa

or send an email to Don Desandre at challenger hobbies Jetkopter@aol.com

Alan...

08-17-2003 Over year old.

heliVoY
Veteran
Location: NJ

Optikaman,

By now I have stopped bleeding. I am off to home depot to buy some gloves. I started on the split pipe for my fuse, and im focusing on the 2 exhaust ports now ... If the pipe I get from VrioUSA for my airwolf is a 1 wall pipe, i will build on the second wall myself too ... Hey, if you still got the pic of the bloody pipe , post it , i dont have it anymore.

by the way, if anyone wants a spot welder, look up "spot welder" on ebay. I got the one Alan and I are using for $159 on ebay, and it works great. It took a few practice runs to get the welds right, for the .007" steel, it takes a split second flick of the switch to get a perfect weld, once you get the switch flicks down, its easy (relatively), and sure beats buying the pipe at prices into the $1000 range ... ( i will say, with all the work that goes into these, the pipes are actually worth that much if you dont want to make it yourself, like TamJet's 3 wall EC-135 pipe, i dont know how the hell he made that ... ...)

www.mcmaster.com sells all sorts of sheet metal varieties and other metalworking goodies and tools.

also, one more point on alans pipe in the H500 .. He said its a dismantled pipe from the MB339 kit, but he did not just stick the pipe in, he only used the metal fom the MB339 pipe, and the harmonica shaped pipe spacers. Alan actually himself welded up the 2 tube sections to custom diameters (inside pipe perfectly fits the HP5's ass side, and the outer pipe perfectly fits the ass on the back of the fuselage. And yea, this was all in under 3.5 hours ...

Wojtek

08-17-2003 Over year old.

heliVoY

Veteran - Location: NJ -

Gona do a pipe welding writeup ...

Hey Alan,

check this out, i got one of the exhaust stacks done for my fuse (its 6 inches long, inside pipe diameter is 50mm, outside is around 65mm), by tuesday i hope to start making the Y split for the pipe (if work does not wipe me out this week) ... this one 2 wall piece took less than 30 min to make ...

If time permits this week, i hope to also work on my website, and finally post it up.Once up I'll do a complete write up on making a 2 wall, split scale pipe for a heli fuse ...

by the way, i have yet to lose more blood doing this

Wojtek

08-18-2003 Over year old.

optikaman

Veteran - Location: EnglishTown N.J. -

The police put that blood there, I'm innocent.

I hope you where able to remove all your DNA from the Crime scene.

08-18-2003 Over year old.

heliVoY

Veteran - Location: NJ -

making angled joints ...

Well, i found an efective way to make good, tight angled joints on the exhaust pipe ....

basically, wherever 2 pipes meet at an angle, both pipes need to be cut at 1/2 of the intended angle. Line the pipes up, and mark notching points which will be used for tab-overlap. This method allows for clean welds on a flat surface. Once the pipes are welded together via the notched tab, a seal ring is welded all the way around to ensure no exhaust escapes into the fuse, and this also gives some more reinforcement to the pipe (not that its needed )

also here are some tips for spot welding, from my experience so far:
--> using wider tips on the tongs produces wider welds that are flatter and a lot cleaner.
--> use some moderate pressure on the tongs when welding, this will help prevent burning through, and poping holes
--> do your math before you start ! radiuses, areas, lengths, angles, etc ....
--> get a good feel for the welder on some scrap metal. I have mine down to where i know just how to flick the switch to get a perfect weld every time (well, almost every time )

here are some shots of the first bent section on the pipe off of the HP5 ...

here is a shot of the seal ring going on

here is the finished section of pipe on the hp5. Next step is to slit the pipe into 2 sections, and angle them further upward. At this time I'm planing a similar notched method for the "Y" joint.

looks like i will be making a pipe myself for the Bell230 also, in addition to the EC-135 pipe underway. This one will be a real chalange as the angle of the exhaust will be rather steep .... here are some shots of the 230 ready to be rigged up with the mechanics ....

and whe making pipes gets boring, there are loads of fun thhings to do with a spot welder

like this dangerous, and mostlikely unstable contraption:

Hey Alan !! look !! no blood !!!

Wojtek

08-27-2003 Over year old.

heliVoY

Veteran - Location: NJ -

Ok, pipe for the 230 is done (well, almost) Here are some pics of the final construction. It was very time consuming, but not as hard as I thought. I learned a few things along the way which i will implement on the EC-135 pipe when I start that (the original ec-135 pipe ended up being made into the pipe for the bell230)

This is the original angled pipe, with a cutout to accept the y split. You can see that to make the Y split, i just cut a straight piece of pipe, and bent it out. For the Bell230, the crossectional diameter of each of the exhaust stacks will be almost as large as that of the HP5's exhaust itself, meaning there will be a lot of expansion room inside the pipe, so hopefully it will run cooler because of this. Reason i did this is because of the steep angling of the pipe.

here is the y split completed .. welding was a bit tricky, and now i know how to better make internal tabs for welding the pieces together.

another shot .. notice the gap at the joint point .. this will need to be covered, and was the hardest spot to weld ..

a quick test fit in the fuse, and to determine angle of the next pipes to be welded on ..

here is a cover plate that will get welded inside to cover up the joint mentioned before ...

here you can see it installed inside the pipe at the y joint .. still had a pin hole left, and later i installed a small baffel internally to redirect the thrust away from the hole, and an outer guard plate was added as will be seen in coming photos ..

shot from inside of fuse while fitting ..

starting on the final pipe sections ..

here is the almost inished pipe ...

i wanted an oval shape to the outer pipes, but the SS was too "springy", so i made these temporary formers, and squezed the pipes into these .. using a blow torch, i heated (red hot) the pipe , and would cool it down with WD40 spray (water would be better, but the SS would corode immediately ) i did this repeatedely untill the pipes more or less maintained the desired shape... even though i will still need an outside brace on the outer pipe to forcet he final shape ..

here is the pipe with the 2 outer cooling pipes mounted ..

amd finally its in the heli ready for final mounting of the top canopy !!!!

Next: time to make up some kevlar fuel tanks, install the electronics, and its flying time !!!

Wojtek

09-03-2003 Over year old.

Peter Wales
Key Veteran
Location: Orlando Fl

That is some outstanding work, well done.

I can tell you it will sound superb as well as I have recently heard a turbine which had the exhausts directed up into the blades and the blade noise was perfect.

Peter Wales
http://scalehelicopters.org

09-03-2003 Over year old.

HOMEPAGE

heliVoY
Veteran
Location: NJ

Thanx Peter !!

Peter, I also have a question for you regarding scale competition, figured you might have some insight ... :

Do you know if it is acceptable to have a separate pipe for static judging, and a difernet one for flight ? On my EC-135 i want to make a scale, functional pipe, but that way, the heli will hover taildown because the pipe would be pointing straight out .. I was thinking of building a second pipe for flight, which would point upward more to ofset the rearward thrust ... Or does a heli have to fly with all the equpment as statically judged ?

thanx

Wojtek

09-05-2003 Over year old.

Rico
Senior Heliman
Location: New-Caledonia(South Pacific)

Great JOB Wojtek

what kind of "heat guard " treatement do you intend to use to protect the inside of the fuse ?
Once again great job and thanks for sharing !
Eric

09-05-2003 Over year old.

heliVoY
Veteran
Location: NJ

Thanx Eric ! ,

im going to to use the heat blanket from vario on all my turbine helis (it looks like foil covered oven mit material .. and also some ceramic heat shielding paint on all surrounding fiberglass areas ..

Wojtek

09-05-2003 Over year old.

Peter Wales
Key Veteran
Location: Orlando Fl

Turbine competitions

The rules say it has to be flown as it is statically judged.

Now, between you and me, dont tell anyone, but the rules also suggest that the static judges should not be the flying judges, so how will they know

Realistically, I would say fitting some small right angle diverters would be acceptable until you just beat someone who really wants to win. Then the arguments will start.

Peter Wales
http://scalehelicopters.org

09-05-2003 Over year old.

HOMEPAGE

Phil Cole
Veteran
Location: Redwood City CA

Wojtek,

The exhaust on Al Wert's Huey is almost horizontal. It points straight back over the tail, aimed at the gap between the main and tail rotors. The angle would be about 15 degrees above horizontal.

I have hovered this heli and it sits flat, or close enough. Hueys are meant to hover a little tail down. There were lots of cameras out while I was doing this, but noone seems to have posted any!

I have no explanation for the level hovering, except that maybe the exhaust jet is dispersed by the downwash from the main rotor. There is certainly a healthy wop-wop noise generated. The Jako may have a thust style turbine wheel fitted (less blade pitch), which could be helping. I'll have a look next time Al brings it out.

09-08-2003 Over year old.

heliVoY
Veteran
Location: NJ

Phil,

was that guey flying a HP5 for power ? thats whats going in my EC-135 ..

thanx

Wojtek

09-09-2003 Over year old.

Phil Cole
Veteran
Location: Redwood City CA

Wojtek,

It's a Len Mount UH1-C with a Jakodofsky PJ-W. Seems to be a nice engine, but a bit on the quiet side.

09-09-2003 Over year old.

DStJohn
Senior Heliman
Location: Ft. Collins, CO

Hi Phil,
I talked to Len Mount about the residual thrust on Al's Huey when we were at Circumgyration. Len said, just as you suspected, that the downwash from the blades break up the thrust. Len told me when he flew the prototype he was all set for it to hover very tail low to counteract the thrust, but was very suprised when it was flat!

So tell me how did that big bird feel?? Just the little hop I saw at Circumgyration was quite impressive. I can imagine it is something else in a sustained hover or forward flight.

Dan St.John
East Coast Scale Helicopters Vario Field Rep

09-09-2003 Over year old.

Elliot
Heliman
Location: Germany

Hi DStJoh,

here you may find some videos of my Len Mount Huey flying around. This was the maiden flight.

This thing is amazing to fly. Look slike the real thing.

Huey Flight Videos

Regards,

Elliot

09-09-2003 Over year old.

HOMEPAGE

Phil Cole
Veteran
Location: Redwood City CA

Guys,

sorry for derailing the thread a little.

Dan,

Hovering the Huey is like the Jetcopter, only more. If you extrapolate from your Skyfox to the Jetcopter to the Huey you will get the idea. I did find that I needed to be quite firm with the cyclic sometimes. Tiny corrections didn't always get the job done. There is plenty of collective available.

The low-RPM head results in a low-RPM tail, so it was a little spongy - like full-scale, I guess. Al should have a speed-up gearbox installed by now.

I wimped out on forward flying as there was a full-scale giving rides at the time.

09-09-2003 Over year old.

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