Oklahoma Willy Viper VW

[perry]

Hi Guys,
here are the latest photos of my 535 Viper and the VW it is going to power.
Cheers
Perry

[Richard OConnell]

Very nice, Perry! How much fuel are you planning on storing on the vehicle?

[perry]

2 x 25 gallons for the turbine and 10 gallons for the VW. Heavy!

[Richard OConnell]

Any idea on the fuel consumption rate of the AB?

[perry]

yup, 22 GPM @ 70 psi. A minute is a long time relatively though

[gidge348]

Beautiful job Perry.

I hope you are going to leave the "patina" (rust) in the Zombie transporter....

Do you know what the consumption of the engine (no AB) will be at full noise?

Ian..

[perry]

Hi Ian,
the engine burns 8.3 GPM @ 100%, so with A/B that's 31 GPM producing around 5500 LBs thrust.

[turbochris]

Has it been run? me thinks you'll need to open the tail the vipers don't make a lot of pressure back there. Where are you located?

[ernie wrenn]

I have plenty of parts for the Viper series..

[perry]

Hi all,
finally got the hot streak working on the Viper 535. Engine starts and runs fine, though the engine backs up on low revs due to the pressure in the tube, might need to open up the nozzle a tad. EGTs are OK though, so i will probably wait until i get the engine properly bolted down and see what it is like at higher revs. A/B solonoid is a bit slow acting, i could really do with a fast acting valve, but i can't find anything better. If anyone has such a valve that will flow 22GPM i would be very interested!

A couple of videos can be found here:

www.youtube.com/watch?v=8qVyFXUMauQ&list=UU75U7ncxDtlUgJEGqiST-Ng

www.youtube.com/watch?v=IPXkslcUYAg&list=UU75U7ncxDtlUgJEGqiST-Ng

And some photos of the finished engine:

Cheers

Perry

[Richard OConnell]

Very nice work! Yeah, having an undersized nozzle can definitely cause back pressure while running the AB. I'll have to watch the vids when I get home

[cursorkeys]

Wow! You can see how much much visual work you've done on it. That's a labour of love

I'd be worried about high power settings with no intake bellmouth as there is the posibility of a vena contracta. The horizontal intake screen will have also decreased the intake area. Do you have the space for a mesh cone so the effective open-space remains constant?

The engine really does seem to labour under the back-pressure on the video, is that just an illusion in the audio or does the RPM really change by such a large ammount?

[perry]

Hi,
you think you have learned everything and then you find out you might get a vena contracta! Please explain what that is?
The engine revs were dropping from around 60% to 53%, but operating the A/B at 75% to drop was only to about 72%.

[rythmnbls]

Beautiful looking engine.

Here's a link to wikipedia on vena contracta en.wikipedia.org/wiki/Vena_contracta . Bsically you need a bellmouth like this one www.youtube.com/watch?v=0KH4ECAv0ho to eliminate the effect and get full airflow into your compressor.

Regards

Steve

[cursorkeys]

Mar 24, 2014 16:17:45 GMT -5 perry said:

Hi,
you think you have learned everything and then you find out you might get a vena contracta! Please explain what that is?
The engine revs were dropping from around 60% to 53%, but operating the A/B at 75% to drop was only to about 72%.

I seem to learn something new anytime someone talks on this forum, some incredibly knowledgeable people here

A vena contracta is when you have a sharp entry to a duct which causes strange flow effects further down your duct. Somebody (racket I think) had a great explaination of how it all works but I can't seem to find it with the search. Wikipedia has a bit: en.wikipedia.org/wiki/Vena_contracta

What I took away the last time it was discussed was that without a bellmouth you risk disrupting the flow into the compressor and, from the compressor's point of view, you constrict the 'functional' area of intake and risk a compressor stall.

I'm sure someone will be along to give you the correct information if I've got it wrong!