marcuskeeler

In my JetCat manual it says that the onboard propane tank can be mounted vertically or horizontally so long as the "offset nipple" is toward the top. What offset nipple? My little tank is like a mini aerosal can with the "nipple" in the centre of one end...

I was just going to lay it down horizontally, that's ok right ?

Marcus

mr_matt

My Feedback: (10)

Hi Marcus,

That manual is a bit out of date. You see the older tanks had the offset nipple, which BARELY allowed a more horizontal installation. You do not want liquid starting gas anywhere near that nipple. With these new tanks, you should install much more to vertical, maybe within 30 degrees of vertical at most.

Regards,

marcuskeeler

Darn it, the motor install is largely complete now (just wiring to go) and the bottle is laying flat horizontal with no place to re-orientate....
I could start the motor with the vehicle lifted over I guess [?] Liquid in the lines will damage the system or just make the start unreliable Matt ?
I could attach it to one of the forward rollcage uprights but it will then be in front of the intake albeit to one side. Is that going to have a huge effect on the motor efficiency ?

As you see, I don't have much real estate to work with. Darn it ! []

rcguy!

My Feedback: (69)

Why use the tank at all? Use the PowerMax can upside down until start is complete OR
convert to Kero start!

Dave

mr_matt

My Feedback: (10)

You want to get some safety wire on the pump nipples, especially the inlet. Also, what kind of hose are you running from the UAT to the pump?

You can tilt the bottle and that will help. I had a totally horizontal tank in my Phantom, and I had to raise the nose to get a clean start until I tilted it up. You just stand the chance of injecting liquid starting gas and this messes up the starting sequence. No real chance of damage but missed starts are something you want to avoid in order to minimize dry running of the bearings.

You also need to tie that vent line (and the other loose items) down or it will get sucked into the turbine. You really need a FOD screen pretty bad!!

What is this model??

Oh and Bob could not really get the software do do exactly what you wanted (a real time replay) Sorry.

marcuskeeler

I'm tempted to agree with you Dave. I've already removed the can and am seriously considering using it externally. I'm a bit honked at the manual being an old version to tell the truth. noth jetCat's fault though.... I bought the motor from a UK Distributor and when I got home I discovered there was no manual in the box. I thought the shop were being ok and sent me the manual I have here but it just looks like they stuffed an older version in the mail to shut me up []

I would use a Kero start but I don't have the headroom between the motor and bodyshell to fit one in. It sits about an inch proud I believe ?

marcuskeeler

OK, will get hold of a wire wrapping tool. It's silicone fuel pipe. I can't use your 4mm piping, it won't go on the UAT nipple.. It's ok isn't it? it's tight on and I guess there isn't any pressure in that line, only suction.

Yep, tied it off already. Those pictures are still build-in-progress.
Picking up the FOD screen from my LHS tomorrow, it came from Graupner (Germany) in 3 days, not too bad.

I guess you mean the car? (You can spot a P80 from 50 yards away, I know LOL). It's my Project FG Marder. I originally had an airstart Sophia in it but I couldn't get a handle on starting it reliably though.
It's pretty well known here in the UK R/C scene, been in a national magazine etc.
[link=http://www.mkeeler.com/models/marjet/]Clickme[/link]

That's a shame. Please thank Bob for his efforts though.

Darryl Usher

I always laded the tank down, it was 2' from the turbine worked fine, by the way "they said" not to use a FOD screen in the beginning.
Darryl

mr_matt

My Feedback: (10)

Hi Markus,

Cool model, good luck with it.

On that inlet line, what you have might work, although I did not think pure silicone worked well with kerosene. There is a lot of suction in that line so I might worry about it collapsing, you can always try it and find out, though that might be hard to troubleshoot.

We normally run 6 mm line from that UAT nipple to the pump, then either run a 6 to 4 brass adapter, or put a very short piece of 4 mm on the pump nipple, put the 6 mm over that and safety wire the whole thing. See the thing you are trying to avoid are air leaks on that suction side. If they are small, they displace a lot of fuel and you will not get full power, if they are big they will shut the turbine down. Many leaks only show up at very high power and of course since they are on the suction side they leave no residue to help you track them down.

Good luck,

marcuskeeler

I picked up some Kerosene fuel piping at the LHS today when I collected the FOD guard. You are right of course Matt, the LHS confirmed that the silicone piping would break down with kerosene. The piping I have looks like silicone but is designed for Petrol & diesel.

mr_matt

My Feedback: (10)

Hi Marcus,

Did you make that grey data cable going into the side of the turbine? Cause if that is an off the shelf telecomunications cable it can damage the ECU on power up.

Regards,

marcuskeeler

I made the cable up Matt. It is a 6 cable pin-to-pin connection. That's ok right ?

I haven't run the motor up yet although I have applied power to the ECU & Radio during power testing. The ECU emmits a little tune on power up, that's normal and a sign of all being ok?

Thanks Matt

marcuskeeler

Matt, with your reference to my manual being out of date, I downloaded the latest manual from your site and it also says that that onboard propane tank has an offset nipple [X(]

mr_matt

My Feedback: (10)

Hi Marcus,

It looks like the little schematic shows an offset nipple, but the wording seemed clear to me, sorry for any confusion, I will get that into the next round of updates.

If you made the cable up and you heard those beeps it should be fine.

Good luck,

marcuskeeler

Ah, so you mean vertcial or 'close to'. Gotcha... I've removed the tank for now and will use it externally for testing. Perhaps I'll have a re-shuffle in the future and attempt to get it back onboard. Sure would be nice to have the car start without assistance, for demos, which I'm sure I'll be giving at local clubs.

mr_matt

My Feedback: (10)

Hello again,

My Stingray has the tank about 25 degrees from horizontal and it works fine. You just want to avoid having liquid propane/butane mixture near the nipple. It does not take a WHOLE lot of mounting angle to assure this, on a partial fill.

Regards,

Gordon Mc

My Feedback: (11)

I think the last part is key ... in my experience these tanks will typically hold enough for 5 or more starts if you put in a full charge. If you only put in, say, a 1.5 second charge that should be enough for one start, and the volume of liquid in the tank will be low enough that you don't need much mounting angle at all

Cool looking toy BTW !!

Gordon

PS Matt - great catch on the tubing and the non-std cable - those eagle eyes of yours are working overtime !

Gordon Mc

My Feedback: (11)

Hey Matt - since this is an off-road buggy ... what's the likely effect of rough rides on the turbine longevity ?

Based on my experience of doing lots of snaps etc with my Bobcat, I know that the gyroscopic effects mean that the engine being banged from side to side can lead to premature bearing wear, eventual compressor wheel rubbing, etc. So, does Marcus need to be careful to limit the terrain type he plays on, to minimize rough rides ?

Gordon

mr_matt

My Feedback: (10)

Good point. This LOOKS like a P-80 (you can just barely see the stinger in one of the photos) so it will be less prone to G related issues, but still they are made for model airplanes, which in SOME cases is a bit more benign environment that an off road RC car!

marcuskeeler

This is an off-road car, but it will never see dirt. It's made for speed runs on smooth asphalt. The wheels are oversized units which will furth smooth the ride.
I do expect some issues with fuel airation although hopefully the BVM will supress it.