Search found 17 matches

by makulit
Sat Sep 10, 2011 10:46 pm
Forum: Ramjet forum
Topic: Ducted Ramjet that is meant to fly.
Replies: 35
Views: 25832

Re: Ducted Ramjet that is meant to fly.

I want to try MgO - Cast it and go? Its strong enough to make hurricane proof wallboard all by itself. Actually, might be able to make a 2D ramjet with wallboard? I like that Idea since it would work with the air vehicle I'm imagining. I like the cork and oak ideas mentioned. The idea of building a ...
by makulit
Sat Sep 10, 2011 8:11 pm
Forum: Ramjet forum
Topic: stack flow or flu effect ramjet
Replies: 3
Views: 2602

Re: stack flow or flu effect ramjet

Drag, turbulence, thermodynamics. It works because of thermodynamics. Drag is minimal at low speeds and since I've not provided a layout yet, it can't really be commented on, ditto turbulence. Your analysis of ramjet operation is not applicable to the subsonic case. Speed is not converted to pressur...
by makulit
Sun Aug 28, 2011 3:03 am
Forum: Ramjet forum
Topic: stack flow or flu effect ramjet
Replies: 3
Views: 2602

stack flow or flu effect ramjet

Ive seen a lot of discussion on how to make ramjets work at slower speeds but haven't seen this yet. The stack or flu effect could get air moving at 50 mph prior to a nozzle that could easily double the speed. To do so the engine would have to inlet 5 meters lower than the outlet nozzle and heat the...
by makulit
Sun Aug 14, 2011 6:37 pm
Forum: Ramjet forum
Topic: Steve's ramjet revisited
Replies: 30
Views: 11978

Re: Steve's ramjet revisited

If you had a thrust augmenter after the PJ, you would draw in cool air and oxygen, which would enhance the performance of a ramjet/afterburner following it, just like Fredde said. You could further enhance performance by cooling the ramjet inlet spike with the incoming fuel, which also makes the bur...
by makulit
Sun Aug 14, 2011 5:02 pm
Forum: Ramjet forum
Topic: 50 mph ramjet???
Replies: 30
Views: 16505

Re: 50 mph ramjet???

My latest project will see me testing the performance of a micro ramjet in the high speed exhaust of a small gas turbine engine. That would be like an afterburner wouldn't it? You might enjoy naca-rm-e6l11 from 1947. Will you be using the high speed stream to drag ambient air along for the ride wit...
by makulit
Sun Aug 14, 2011 4:27 pm
Forum: Ramjet forum
Topic: "Flat" Ramjets as in Fleissners Patent, feasability?
Replies: 15
Views: 9868

Re: "Flat" Ramjets as in Fleissners Patent, feasability?

Regarding rotating ramjets: Assuming a tip speed of 600 mph and a diameter of 6 feet, your rpm would be 2801, which is equivalent to the rotation of a car tire at 200 mph. The bearings could be pretty conventional and still work. Using fuel to cool them would probably be nice, and the rotating blade...
by makulit
Sun Aug 14, 2011 3:19 pm
Forum: Ramjet forum
Topic: "Flat" Ramjets as in Fleissners Patent, feasability?
Replies: 15
Views: 9868

Re: "Flat" Ramjets as in Fleissners Patent, feasability?

Ouch - just lost a long paragraph. my fault. anyway. The US government (NACA) did test stand and flight testing on rectangular ramjets in 1947. The flight article was a short wing section mounted under a P-61. This ramjet was developed for vehicles like the Hermes B winged cruise missile second stag...
by makulit
Sat Aug 06, 2011 5:53 pm
Forum: Ramjet forum
Topic: Static Ramjet?…
Replies: 15
Views: 9496

Re: Static Ramjet?…

If your fuel injection / combustion is done in a way that carries the velocity, like an ejector jet, then you could get some airflow going at zero forward speed. The idea of regeneration from the thrust augmenter seems like a good one. A loop like that should raise the overall system pressure. Raisi...
by makulit
Sat Aug 06, 2011 5:31 pm
Forum: Ramjet forum
Topic: 50 mph ramjet???
Replies: 30
Views: 16505

Re: 50 mph ramjet???

Update: I revised my assumptions regarding the flat plat at 10° for the no centerbody design and used airfoil sections instead and was able to get the no centerbody drag to be about the same as the drag on the centerbody. Meanwhile I have stumbled upon a treasure trove of NACA documentation and I in...
by makulit
Fri Aug 05, 2011 2:02 am
Forum: Ramjet forum
Topic: 50 mph ramjet???
Replies: 30
Views: 16505

Re: 50 mph ramjet???

Thanks for your comments. I will probably keep the center bodies during development because it simplifies construction (remember I'm building engines whose dimensions are constant in one dimension) because I can tweek the positions easily. I don't know if everyone already knows this but if you wante...
by makulit
Thu Aug 04, 2011 3:44 am
Forum: Ramjet forum
Topic: 50 mph ramjet???
Replies: 30
Views: 16505

Re: 50 mph ramjet???

For thrust, I'm using Decker's chart from practical ramjet design, extrapolating for the lower speeds. If the thrust is actually better, awesome. If I can cut out a stage, another awesome. Regarding the centerbodies and drag: The bodies are streamlined, the airspeeds are slow, and unless I missed so...
by makulit
Wed Aug 03, 2011 4:26 am
Forum: Ramjet forum
Topic: 50 mph ramjet???
Replies: 30
Views: 16505

Re: 50 mph ramjet???

Here's what I was thinking 20-30 lbs thrust at 50 MPH
by makulit
Tue Aug 02, 2011 5:20 pm
Forum: Ramjet forum
Topic: 50 mph ramjet???
Replies: 30
Views: 16505

Re: 50 mph ramjet???

Yes, I'm worried about the practical length too. To counter that I'm thinking of several or maybe many smaller jets in the first and second stages. To simplify construction they would be 2D ramjets - like little boxes with open ends and center bodies. And really, I would have a tough time building a...
by makulit
Tue Aug 02, 2011 2:45 am
Forum: Ramjet forum
Topic: 50 mph ramjet???
Replies: 30
Views: 16505

Re: 50 mph ramjet???

Well I'm counting on the jet to be able to double the velocity in each engine. In my first thought experiment on this I imagine rolling down the highway at 50, 3 stage ramjet on the roof. So after the first one, the velocity is 100mph. The air is also 600°F or so. Next engine takes that air and some...
by makulit
Mon Aug 01, 2011 1:55 am
Forum: Ramjet forum
Topic: 50 mph ramjet???
Replies: 30
Views: 16505

Re: 50 mph ramjet???

I have a deep interest in slow ramjets because I would like to build something like a solar updraft tower, except that I'd like what I build to be a lot more compact. Basically ramjets make the air come out the back end faster than it went in, right? and the faster it goes, the greater the thrust yo...