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Old 04-03-2014, 02:06 AM
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blackshire blackshire is offline
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Default Micro ramjets? (RE: 'copters)

Hello All,

This week I received a copy of Jet Aircraft Simplified by Charles Edward Chapel (1954 Edition, Illustrated). In addition to jet airplanes and rocket planes, it also covers "tip-jet" helicopters, which were/are similar in concept to the model rocket mono-copters and the Jetex helicopters; these helicopters used pulsejet and ramjet engines mounted on the tips of their rotors' blades. This got me wondering:

While model pulsejet engines don't appear to be workable much below the size of the Dyna-Jet Red Head engine, might model-size subsonic ramjets *not* be so severely constrained as regards their size? Would a small (say, 3/4" diameter X 1-1/2" long, or perhaps a bit larger) subsonic ramjet work as a tip-jet on a model helicopter? I imagine such a tiny ramjet engine wouldn't be very fuel-efficient, but neither were the full-scale tip-jet ramjets. However, for a simple F/F (Free-Flight) or micro-R/C model helicopter, a short engine-running duration would not only *not* be a problem, but it would actually be an advantage, since the model wouldn't fly too far away (either beyond the flying field boundaries, or beyond the effective range of the micro-R/C transmitter). Also:

There are some good scale subjects for such tip-jet ramjet helicopter models--the Hiller-Hornet, the Hiller HJ-1, and the McDonnell XH-20 "Little Henry." Many thanks in advance to anyone who can shed light on this!
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Old 04-03-2014, 03:19 AM
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I found an online version here: Jet Aircraft
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  #3  
Old 04-03-2014, 04:33 AM
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blackshire blackshire is offline
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Quote:
Originally Posted by mycrofte
I found an online version here: Jet Aircraft
That's the book--Thank You! While it isn't fully opening for me at the moment, the large file sizes and my computer's age are likely factors in that. :-) Also:

The book--which is (as described on the dust jacket) organized so that it can be used as a one-semester course--is Jet Aircraft Simplified by Charles Edward Chapel (I'm presuming it's the 1954 Edition, Illustrated--there was also a 1950 Edition). Like all good books of this type, Jet Aircraft Simplified (which also covers ramjets, pulsejets, and rocket propulsion, including suborbital sounding rockets, rocket planes, and JATO units [Jet-Assisted Take-Off aircraft assist rockets]) also includes other things that are readily "connect-able" to school math, science, and even history classes. For example:

Newton's three laws of motion and early jet propulsion devices (Hero of Alexandria's aeolipile, Wan-Hoo's rocket-powered chair, Chinese rockets, Isaac Newton's steam-rocket carriage, etc.) are covered. It contains the simple formula (with an example) for calculating the relationship between the thrust and horsepower of a jet or rocket engine. The gas turbine (jet engine) operating cycle (called the Brayton Cycle) is compared--in illustrations and text--with the Otto Cycle of reciprocating (piston) engines, and the turboprop (propjet), ramjet, pulsejet, and rocket (liquid- and solid-propellant) operating cycles are also covered in these ways. Simplified, illustrated schematics of jet engine fuel and lubrication systems are also included. And:

The book also shows how to read multi-data graphs. On one page is a graph showing the changes in air pressure, temperature, and velocity through the inlet diffuser, compressor, combustion chamber (combustor), turbine, and exhaust nozzle of a non-afterburning turbojet engine. Another graph below it shows these parameters for an afterburning turbojet engine. The multiple graphs give a picture of what's going on inside these jet engines, and where. Plus:

For drafting students, the book is loaded with three-view, exploded-view, perspective, and cut-away drawings of jet and rocket engines and the aircraft they powered, all of which they could draw from for practice. Print-outs of these drawings would be perfect for them to use for practicing scaling-up (or scaling-down) the drawings (including their complex curves), using the techniques in Paul Del Gatto's Jetex books (re-prints of which are available from Rocket Science Books, see: http://rocketsciencebooks.com ).

I hope this information will be helpful.
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http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
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Old 04-03-2014, 01:11 PM
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Tip motor rotors were used on Rotary Rocket and the initial testing happened at the Rattworks shop locally!!

Tech Jerry
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Old 04-04-2014, 02:11 AM
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Quote:
Originally Posted by Jerry Irvine
Tip motor rotors were used on Rotary Rocket and the initial testing happened at the Rattworks shop locally!!

Tech Jerry
Were they LOX/kerosene? Although they were never as common as ramjet or pulsejet tip-jet helicopters, one or two small tip-jet helicopters used hydrogen peroxide monopropellant rocket engines on their rotor blades' tips. Gluhareff Pressure Jets (I think they burn propane, but I'm not sure) might also work as tip-jets.
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http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
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Old 04-04-2014, 06:59 AM
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Monopropellant HTP IIRC.

Quote:
Originally Posted by Wikipedia, Rotary Rocket
The vehicle was also unique in planning to use its helicopter-style rotors for landing, rather than wings or parachutes. This concept allowed controlled landings (unlike parachutes), and it was 1/5 the weight of fixed wings. Another advantage was that a helicopter could land almost anywhere, whereas winged spaceplanes such as the Shuttle had to make it back to the runway. The rotor blades were to be powered by peroxide tip rockets. The rotor blades were to be deployed before reentry; some questions were raised about whether the blades would survive until landing.

Each rotor was powered by a 350-lbf (1,560 N) hydrogen peroxide jet, as intended for the orbital vehicle.[5] The rotor assemblage was tested in a rock quarry before installation on the ATV.


Tech Jerry
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Old 04-05-2014, 07:05 PM
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Quote:
Originally Posted by Jerry Irvine
Monopropellant HTP IIRC.

Tech Jerry
Thank you--that was certainly a workable (and proven) solution for the rotor propulsion, having been used on a few helicopters before--but as for the rest of ROTON's systems? Many more self-pumping liquid-propellant rockets (where canted nozzles power the pumps) have been proposed (a Russian GIRD design [it never went further than a solid-propelled test airframe], the Northrop XP-79's rocket engine [the XP-79B used two Westinghouse J30 turbojets instead], and ROTON) than flown.
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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
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