Tenney's rotary Dynajet

[Mike Everman]

So cool to have found this. Were you around when they played with this, Jerry?

[Viv]

Hi Mike

love that one, must be a bit of pressure gain with it going around and around like that self starting too I shouldn't wonder.

the other wonder is we have not seen it before! all those terabytes are a pain to sift through at times but I do love the way he mounted the valve head

Viv

[hinote]

Hi Mike

love that one, must be a bit of pressure gain with it going around and around like that self starting too I shouldn't wonder.

the other wonder is we have not seen it before! all those terabytes are a pain to sift through at times but I do love the way he mounted the valve head

Viv

I can provide an interesting sidelight to this thread:

In the late 1970's I travelled to Ohio to meet Dick Schreder, one of the icons in soaring during the '50's and '60's. He successfully developed high-performance sailplanes (for that era) using the best of aluminum techniques. He was also responsible for designing and selling parts for excellent homebuilt designs.

Dick saw the composite revolution as it developed and widely affected sailplane design and production. He proposed an interesting design using his RS-15 fuselage, tailboom and tailfeathers--but using a very high aspect ratio wing with carbon fiber spars.

In addition (the real subject of this post!) he experimented with a pulsejet design which integrated a valved intake assembly in the hub of a 2-blade stainless steel prop, and the exhaust was deflected at the tips of the prop by 90 degrees to create the necessary torque to turn the prop and provide power to self-launch a sailplane. The prototype had the half-shells of the prop formed over an oak buck, and welded along the leading and trailing edges. The weight (as I recall) was something like 12 lb and it produced 50 lbf thrust.

Although the TSFC wasn't spectacular the simplicity of the design allowed for easy deployment and storage, and self-starting in-air was virtually guaranteed due to windmilling. On the ground, the beast was started by inducing fuel into the hub combustion chamber area and the resulting "bangs" would induce low-speed rotation and warming of the assembly. Careful monitoring of the fuel flow on an increasing flow basis would allow it to eventually transition to full power as a pulsejet.

If you google for "schreder pulsejet" you'll get a number of hits. Dick never took either the sailplane or the PJ/prop any further, but I had an opportunity to see his efforts as they were currently developing.

I'm pleased that I was involved in this era of sailplane development as well as an interesting app for a unique pulsejet.

[Viv]

Hey Bill how are you? hope all is well with you and yours.

That is a very interesting addition to not only this story but the original of Schmidt's propellor, I always wondered if any one had actually built some thing to see how it performed, a real 50 lbs is not bad at all for the time and materials technology available.

Viv

[hinote]

Hey Bill how are you? hope all is well with you and yours.

Hi, back to you--and Happy Holidays to you (and the rest of our fellow PJ enthusiasts)!

I wish I could report that all is well, but the US financial situation and a puffed-up, uncaring, BMW M-series driving financial officer have created a disaster that I'm going to have to remedy myself. I can only say that everybody out there should be darned careful in these difficult times, and that each of us can be better at handling our own financial affairs than any paid assistance can be--especially if we educate ourselves about the system as it currently operates. I'm looking forward to a fabulous recovery in the near future. Ask me again this time next year!

That is a very interesting addition to not only this story but the original of Schmidt's propellor, I always wondered if any one had actually built some thing to see how it performed, a real 50 lbs is not bad at all for the time and materials technology available.
Viv

There's some evidence that this story was a little hyped; I got to see the prototype but not to see it run--and I never found any evidence of credible witnesses. Still, it was a concept worth pursuing, and would have been highly applicable to self-launching sailplanes (light weight and excellent power density).

Also, I feel this concept is worth pursuing--but with a dedicated exhaust duct; the necessary "skin" to form the propellor shape could be added outside the duct tube and would be easy to form with ribs attached to the duct. The crude shape of the prop would hardly be conducive to PJ performance and should be separated from the motor itself, IMO.

[Mike Everman]

Also, I feel this concept is worth pursuing--but with a dedicated exhaust duct; the necessary "skin" to form the propellor shape could be added outside the duct tube and would be easy to form with ribs attached to the duct. The crude shape of the prop would hardly be conducive to PJ performance and should be separated from the motor itself, IMO.

Ed Zachary. Well put, and er, yeah, what He said. I'm ssssoooo close to putting one of mine to metal.

[dynajetjerry]

Hi, Mike & all,

I have not seen this particular patent application before and appreciate being made aware of it. It is not among the material I got from Patty Tenney. Obviously, it is a very early concept and, almost certainly, was never constructed. I never saw anything that resembled this device; but, keep in mind I went to work for Bill in May, 1949, more than 3 years after the patent application was filed. It was an attempt to cover as many as possible ideas for applications of the pulse-jet principle, a very common practice among "inventors." Though no dimensions are shown, my past experiences lead me to believe a minimum size for this device would be about 2 feet diameter. Even then, useful life of the reed valve would be rather short.

My quick and casual examination of the drawings leads me to believe many changes would need to be made before such a device would actually work. Notice the inclusion of provision (81, 82,) for cooling air to flow over the anchoring plate (30.) I also see a possibility that operation might be improved by a reversal of the outer housing so that it would resemble a normal "squirrel cage" blower system.

Charlie Marks was a brilliant and innovative man but he left Bill in 1947, so I never met him. I am very sorry for that misfortune. Charlie did rejoin Bill in Minnesota during the early 1990s but left after several years, dying soon after.

Thanks to all of you.

Jerry

[Bruno Ogorelec]

To me, it looks as if the thing would benefit from Stage 2. Instead of having a single tangential exhaust from the outer casing, I'd duct the mixture of exhaust gas and fresh air around the lip of the backing plate and onto a radial turbine, as on a Whittle turbojet. See the very crude sketch below.

Of course, the free air space around the pulsejet wheel should probably be reduced greatly and the fresh air intake to the outer chamber aerodynamically profiled, the gas channel towards the turbine should broaden progressively instead of narrowing etc. etc. This is just the gist of the idea, not a precise illustration.

Also, the sketch shows a jet engine, but this would not be a good application, I guess. Shaft power would probably be a rather better bet.

[Bruno Ogorelec]

More ideas coming. The air intake to the outer chamber should be lengthened, so that the gas flow sucks fresh air through a longer duct and generates positive fresh air pressure (ram pressure) on the combustion chamber intake. Eliminate the valves; this thing would happily run without them, given proper geometry.

Looks like a gas turbine that a good blacksmith could have fashioned easily in the Middle Ages. He'd have been burned on a stake, of course, but I guess no sacrifice for knowledge and progress is too great.

[Mike Everman]

ha ha
Hi Bruno!
Burned on a stake. I hope I come up with something that gets em gathering up firewood. ha

[alex smikle]

Hello again everyone.
I was looking at the design and i could just imagine what a compressor on that shaft could do, it would have to be geared to get up to spooling speed, maybe with a planetary gear set. It would essentially be a supercharged pulse jet (hmm i wonder how the cycle would look?)
The compressed air could be rerouted to the intake to provide nice combustion; that above atmospheric pressure and temp of course. Compressed air means more power!
A clutch could be used on the compressor so that the compressor is only activated when the engine is running at a certain speed to negate any inertia it would have due to the compressor upon starting.
However before i jump the gun, would the compressed air affect the intake action of the engine?

[Bruno Ogorelec]

Hello again everyone.
I was looking at the design and i could just imagine what a compressor on that shaft could do, it would have to be geared to get up to spooling speed, maybe with a planetary gear set. It would essentially be a supercharged pulse jet (hmm i wonder how the cycle would look?)
The compressed air could be rerouted to the intake to provide nice combustion; that above atmospheric pressure and temp of course. Compressed air means more power!
A clutch could be used on the compressor so that the compressor is only activated when the engine is running at a certain speed to negate any inertia it would have due to the compressor upon starting.
However before i jump the gun, would the compressed air affect the intake action of the engine?

Why do you think compressor inertia is a bad thing? It would just take a while to spool up. It doesn't bother turbine engines; shouldn't be a bother here either.

No need to 'reroute' intake if a compressor is used. Just put the compressor upstream from the combustor, as in a turbojet or turboshaft engine. Compressor-combustor-turbine. In fact, this looks like a pretty compact layout, with more girth than usual but very short. Probably not very good for a jet engine, but good for a turboshaft.

Compressed air would sure as hell affect intake action. You would no longer need the valves. Your power output would shoot up dramatically, too.

[Mike Everman]

Hey Bruno! Just hey!

[Bruno Ogorelec]

Hey Bruno! Just hey!

Hey right back at you. How's things?

[sockmonkey]

Once you have the compressor does it still really need to pulse instead of burn steadilly?