Rocketry Planet

FORT COLLINS, Colorado USA — Edward Wranosky of Alpha Hybrids has posted photos and video of his recent test firings of his conceptual integration of an aerospike nozzle on one of his experimental hybrid rocket motors. Wranosky stated he saw an increase of about 2.5% on a non-optimized version of the motor.

Aerospikes are a topic of curiousity for rocketry enthusiasts, because of the unusual way they look and perform. In a traditional rocket motor, a nozzle that is designed to give optimal performance at ground level will not work as efficiently at altitude.  An aerospike nozzle is designed so that the airflow "adjusts" with the given altitude.

"This was the 2nd generation - still getting all the kinks worked out and making sure they flow like they should. The next generation will be made to match the At/Ai ratio of a conical divergent nozzle that I've done 100's of tests on," Wranosky stated in an online post yesterday made to the 'hybridrocketmotors' Yahoo Groups! discussion list.

According the Wikipedia website, "[t]he idea behind the aerospike design is that at low altitude the ambient pressure compresses the wake against the nozzle. The recirculation in the base zone of the wedge can then raise the pressure there to near ambient. Since the pressure on top of the engine is ambient, this means that base gives no overall thrust (but it also means that this part of the nozzle doesn't lose thrust by forming a partial vacuum, thus the base part of the nozzle can be ignored at low altitude)."

An article by Pratt & Whitney Rocketdyne indicates that aerospikes work poorly between Mach 1-3, where "wind tunnel tests indicate a drop in nozzle efficiency due to the slipstream turning into the nozzle region. When this occurs, the local pressure into which the engine exhausts drops below ambient pressure, and the nozzle flow field adjusts to an effectively higher altitude. As a result, the pressure peaks on the nozzle surface are reduced, and overall performance suffers. (Source: http://www.engineeringatboeing.com/articles/nozzledesign.htm)"

Whether aerospike nozzles ever become available for the hobby rocketry community remains to be seen, but the concept is certainly high in cool factor.

Website: http://alphahybrids.blogspot.com/

Reader comments:

#1 Re: Article: Alpha Hybrids tests conceptual aerospike hybrid motor

I wonder how much it erodes? Would it be more tolerant of erosion than a typical nozzle? I mean it is thicker...

Also... what about landings? I would be afraid of it breaking or burning a hole in something

New Ocean on 08-26-2008 12:16 PM

#2 Re: Article: Alpha Hybrids tests conceptual aerospike hybrid motor

After 3 firings, and cleaning the buildup from it I could see only a tiny bit of erosion on the lip of the spike. The pintle didn't have any. When measured it was about .002".

As for landings, I'm just doing the up part. The flyer is responsible for the down part If you break it I guess you'll just have to buy another

Edward

edwardw on 08-26-2008 02:01 PM

#3 Re: Article: Alpha Hybrids tests conceptual aerospike hybrid motor

Quote:

After 3 firings, and cleaning the buildup from it I could see only a tiny bit of erosion on the lip of the spike. The pintle didn't have any. When measured it was about .002".

As for landings, I'm just doing the up part. The flyer is responsible for the down part If you break it I guess you'll just have to buy another

Edward

Finally! I've been looking for a rocket where the fins need to be swept back to protect the nozzle - things are finally right in the world.

UncleVanya on 08-26-2008 03:22 PM

#4 Re: Article: Alpha Hybrids tests conceptual aerospike hybrid motor

If you don't use the fins to protect the nozzle, one can put a rod out the back (well attached) with a very blunt end for landing drag addition. It pokes into the ground and reduces forces on other rearward projecting parts.

I urged that on the huge Mars Lander rocket.

Just Jerry

Just Jerry on 08-26-2008 03:40 PM

#5 Re: Article: Alpha Hybrids tests conceptual aerospike hybrid motor

Quote:

If you don't use the fins to protect the nozzle, one can put a rod out the back (well attached) with a very blunt end for landing drag addition. It pokes into the ground and reduces forces on other rearward projecting parts.

I urged that on the huge Mars Lander rocket.

Just Jerry

What a great idea. What do you suggest to use on smaller MPR and HPR rockets? Have you seen a wooden dowel work? I'd assume that it would be lighter than a threaded rod. It would probably need to be setup for replacement in the event of a hard landing.

UncleVanya on 08-26-2008 03:53 PM

#6 Re: Article: Alpha Hybrids tests conceptual aerospike hybrid motor

When O When will we see the hybrid motors for sale and all certified/ready to go ??

Can't wait to be the first guy on the block with a Alpha Hybrids Rocet Motor !!


Darin

MACH5 on 09-01-2008 05:19 PM

#7 Re: Article: Alpha Hybrids tests conceptual aerospike hybrid motor

congrats on the aerospike and flight:O) here was ours in 2006, no flight yet.

http://en.wikipedia.org/wi...e_2006_mach_daimonds.jpg

4spacecowboy on 10-19-2008 05:48 PM

#8 Re: Article: Alpha Hybrids tests conceptual aerospike hybrid motor

Quote:

congrats on the aerospike and flight:O) here was ours in 2006, no flight yet.

http://en.wikipedia.org/wi...e_2006_mach_daimonds.jpg

True "aerospikes" do not produce mach diamonds as they are optimally expanded.

Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto

Anthony Cesaroni on 10-19-2008 06:34 PM

#9 Re: Article: Alpha Hybrids tests conceptual aerospike hybrid motor

then... you might want to tell rocketdyne, EaC, and a few others that they shouldnt have claimed that their engines/motors were not true aerospikes (look at their pics):

http://en.wikipedia.org/wiki/Aerospike_engine

also, the pic i posted was just a split second pic of the motor building up to full thrust which does not have mach daimonds during full thrust as the chamber pressure had reached its designed pressure. i had done an AIAA paper on aerospikes and aware of an aerospikes true optimization. since 2006, i have become a professional rocket propulsion engineer myself and continuing work on outside of the company on hybrid and bipropellant aerospike applications.

4spacecowboy on 10-19-2008 06:45 PM

#10 Re: Article: Alpha Hybrids tests conceptual aerospike hybrid motor

on another note, i admire cesaroni's work with aerospikes and look forward to seeing more public work in the future.

4spacecowboy on 10-19-2008 06:49 PM

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