Mid-Jet gets ready for RC !

[Chadly33]

So Im getting a bit closer to finishing the rail off . Got the steering setup as well as the brake system ! Will have the brake stay on until the last part of throttle servo travel, I have a small fuel tap and a RC mixture screw that I was going to hook to the same servo and run to the augmentor for an after burner but havent decided yet.

[Mike Everman]

Oh, that thing is a work of art, man! I can't wait to see it go.

[Chadly33]

Got the rest of the RC gear installed today, still no afterburner as yet and I will finish the body off this week at work! just hoping it all works out as well as I planned, may still have to go with the twin engines to improve the thrust to weight ratio though. Still deciding on what colour to paint it when its finished, will be using a metalic two pack as we have plenty of it at work!

[Chadly33]

Short vid of engine running in the chassis!http://au.youtube.com/watch?v=bfE_ANeTmS0

[Chadly33]

Got the rear wing and the body cover done today, all thats left is front wing and afterburner!

[Chadly33]

This is the initial test of the pulse rail, still having tuning problems. It wants to over fuel easily even with the preheat line it still wants to spit liquid into the CC. As I originally calculated it really needs the second engine to improve the thrust to weight ratio, so I will build the second engine and iterconnect the two with a blast tube. It would look better with a engine on each side anyway and free up a lot of room in the chassis.http://www.youtube.com/watch?v=if4HJHVMOWc

[larry cottrill]

Man, that is way cool!

You will really have something once all the bugs have been run out.

L Cottrill

[Chadly33]

Here is the engine, if anyone has any ideas for it please post them up Im all ears!

Cheers,
Chad..

[milisavljevic]

Here is the engine, if anyone has any ideas for it please post them...

If you are really open to advice, I will be happy to analyse the Mid-Jet And make some suggestions
that you may wish to consider for future modifications or developments. Give me a couple of days?

Btw., GREAT project! Love the RC Dragster concept.

Cheers!
M.

[Ghrey]

A couple of obvious Ideas for posable improvement, also sent directly.


1. A hemispherical CC front wall may improve the acoustics and fluid flow, but only ( in my view ) modestly.

2. I will say it first, just because I can, a tapered CC rear, 45 degrees or so, may help flow. I see this Idea as bad for the engines acoustics and probably not a useful mod.

3. Some may argue that the tail pipe design is faulty, I would not change it, it is very good in my view. 55% Larger than the minimum Exhaust Dia. may be the "magic" Number for a choke.

All will change tuning, possibly radically but I doubt that. Sorry no drawings. limited time.


In any event I am probably wrong in many of my basic assumptions.

Edit: in 3. "of" became "Larger than the"





If you recently received a "mail box full" response from my e-mail address, it is now fixed.

[Chadly33]

Thanks M. any ideas are good ones as I only build by feel ! I downloaded Uflow but dont have a clue how to use it and there are no help files with it ?

[Mike Everman]

There's no real tutorial other than what's been posted around here. some good stuff and a model to start with here:
viewtopic.php?f=3&t=702&hilit=uflow+tutorial

It's finicky, but really can teach you some things. However, I've not used it at all in probably two years. Best advice on the nuances would likely come from Larry, as he uses it constantly. One difference in the methodology that Graham and I started using was instead of a pop in the CC and a lot of different temperature estimates present at the time of the pop, we made a mostly uniform high temp on the length, and a low pressure in the cc to start the cycle at a point representative of the lowest partial vacuum in the cc. Easier to set up, and higher fidelity.

In any case, 1d is not going to deal with steep changes in diameter, nor represent turbulence (for instance, beyond a flat cc head plate). For this reason, you needn't concern yourself with intake flares unless they are long and shallow.

[Chadly33]

Ok ! Building a new engine for the rail! more power , rounded triangular CC , twin exhausts, larger capacity overall. Will be installed upside down so all you will really see of it is the bottom of the CC and the twin pipes coming out the back. The rail is currently on display at the local hobby store and is currently the talk of the place, so will have to get it back once the new engine is built!