The double flight engine

[Anthony]

This started out as a basic design made around a rack-based (can slide the core foraward or back) Reynst "pusher" engine, with a versatile tail section. First, it was a quite compact pulsejet, my idea being of one where the Reynst would help the pulsejet getting up to speed and slowly leaving the job to a ramjet.

However, Rossco tought the engine would have more potential with the whole "tube" being a pulsejet too, and having a longer tail section. This would allow (quite unsurprisingly) more thrust, and a better flow...

But I'm too tired for further explanations so I'll let the image talk (and Rossco too, if he wants!).

P.S. I am aware of the fact Reynst engines are quite... touchy?

[Greg O'Bryant]

Anthony; Do you know if anybody has made an engine like this? I have had some similar thoughts. It makes sense to combine a ram jet with a pulse jet, kind of like a "pulse cumbustion ram jet" so that it can get up to speed and get good compression. Acording to Bruce Simpson's numbers his 50 lb lockwood engine has a better fuel consumption than a similar sized ramjet at sub sonic speeds. Also if you were to make a helicopter with tip mounted ram jets, you would have to spin the rotor very fast to get it going. Why not let the pulse combustion get the rotor up to speed. If a pulse jet is already more eficient than a ram jet at slow speeds imagine if you combined the two. It would be an engine more eficient than either of the two alone. My own personal opion that a hybrid engine like this would have to have the ram compression added at the inlet and outlet so that it wouldn't disrupt the normal flow of the pulse jet. Something that your engine does very well using the reynst combuster. And remeber all of the heat that pulse jets give off, if that heat was used on compressed air it would furhter increase its power. I like the way your engine has a large tailpipe to add extra mass to the thrust. Looks very promising to me, However most of the engine ideas I have are only in my head and have not been tested. Just seems to me to be the next logical step. good luck

[Anthony]

Well, I haven't seen such designs, but I have little experience in pulsejets. I am sadly not equipped to build a prototype, so this is just an idea, on paper.

The transition from pulse to ram combustion would be done automatically. While gaining enough speed, the "tube" pulsejet starts to work as a ramjet because of the velocity of incoming air (well, on paper!). The Reynst itself would become unnecessary, and the fuel flow would be stopped.

Then, the "rack mounted" Reynst/nose-cone might be a useful thing. Would sliding the Reynst backwards, leaving a bigger intake area, be a good thing to do while in ramjet mode?

[Bruno Ogorelec]

Anthony, I definitely think this is one of the important layouts to try. Probably not the easiest to develop, but potentially very important. Here's how I imagined it some time ago. Note that my layout did not try to be a ramjet at higher speeds, like yours, but purely a pulsejet. It is based on Dynajet-style parts.

[Rossco]

Bruno,
Im just revisiting some old ideas in relation to my remolded ideas on the reynst, let alone intermitant combustion.
This one is a goer! If i encased my overworked "true reynst" model, it would emulate this pretty well, other than two main distinct factors.
One is the intake length and venturi, which i think could get tricky, as it will be adding a new accoustic component.
And two, is the exhast line up and slit. Ive come to the conclusion, in my model at any rate, that it is benaficial to have only half the intake area covered by the exhast. This has an added bonus ease of starting. In your configuration, if the tail tapered to half the diameter at the slit, and only covered the top half of the intake, convection would do the most part of the refresh and initial fueling fill.
This discovery has opened my eyes to a number of old ideas with new possibilities, that where abandoned from hard starting issues.

I am now back on the idea of Anthony's ram jet ducting too, although i just never see it quite as "fueled" as you do. It does three (actualy a lot more) jobs, diffuses high velosity incoming air, cooling the chamber/heating the air, rectifying the high press low velocity air to the intake, and augmenting the intake output. Venting to the rear an augmented, acumulated, heated mass...thrust. Yes, go on, stick an afterburner in there and throw some flames! I think your just a pyro, and want to get as much fuel in there in as many places as you can! HA.

Anthony, were back on! Ill fill you in when i "see" you next, get your mouse ready for some streaming from that mind of yours.

Rossco

[Bruno Ogorelec]

Bruno, this one is a goer!

Of course it is! Have you ever doubted me? :o)

…other than two main distinct factors.
One is the intake length and venturi, which i think could get tricky, as it will be adding a new accoustic component.
And two, is the exhast line up and slit. Ive come to the conclusion, in my model at any rate, that it is benaficial to have only half the intake area covered by the exhast. This has an added bonus ease of starting. In your configuration, if the tail tapered to half the diameter at the slit, and only covered the top half of the intake, convection would do the most part of the refresh and initial fueling fill.
This discovery has opened my eyes to a number of old ideas with new possibilities, that where abandoned from hard starting issues.

Rossco, my ideas were based on the writings and drawings of other people, with no practical experience of my own. Such theoretical thinking can only go this far. You are basing your conclusions on practical results and experience. That has greater weight than any theory I can spin. I say, go for it and we'll record it for posterity and explain it neatly after the fact. :o)

I'm really glad you are doing this.