Converting HP to thrust with a jet engine.... A motor jet estimation?
Converting HP to thrust with a jet engine.... A motor jet estimation?
(OP)
I'm looking to verify some a figure on the conversion of HP to Thrust with the use of a jet engine. Basically a motor-jet
I've been told 7lb of static-thrust roughly for every 1HP fed into the compressor. That sounds a bit high to me.
Obviously there is a lot to it but I just want ball-park figures. Making whatever assumptions need to be made, what is a rough approximation? Say i'm going to build a motor-jet and I want to use a 100hp motor. What can I roughly expect to get in return for Thrust?
I've been told 7lb of static-thrust roughly for every 1HP fed into the compressor. That sounds a bit high to me.
Obviously there is a lot to it but I just want ball-park figures. Making whatever assumptions need to be made, what is a rough approximation? Say i'm going to build a motor-jet and I want to use a 100hp motor. What can I roughly expect to get in return for Thrust?





RE: Converting HP to thrust with a jet engine.... A motor jet estimation?
Cheers
Greg Locock
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RE: Converting HP to thrust with a jet engine.... A motor jet estimation?
RE: Converting HP to thrust with a jet engine.... A motor jet estimation?
Your second question is much better than the first.
However a moments googling takes us to http://www.angelfire.com/art/jetengine/
which has a whole bunch of numbers.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Converting HP to thrust with a jet engine.... A motor jet estimation?
if you mean a typical turbo-jet, i'm not sure there is a relationship. consider jet engines have pwoered described as thrust, and propeller engines have their pwoer described by hp.
RE: Converting HP to thrust with a jet engine.... A motor jet estimation?
Power is force times velocity. Horsepower does not convert directly into thrust, unless you keep speed constant.
I remember visiting a marine museum and looking at a 6 foot diameter propeller from a fishing boat with a 17HP engine. On my uncle's 200HP boat, the propeller was something around 1 foot diameter.
If the fishing boat goes 15mph, there is a little over 400lb thrust. This is believable to me.
--
JHG
RE: Converting HP to thrust with a jet engine.... A motor jet estimation?
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.g...
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Converting HP to thrust with a jet engine.... A motor jet estimation?
Mathematically, you cannot convert HP straight to Thrust... But that is not what I'm trying to do...
However, you CAN convert HP to thrust through thermodynamic/mechanical means which is what the question is about. When using a purely "jet" engine (regardless of how the compressor gets its power), what type of ratio can be achieved.
IRstuff this method will give the total power consumption of the engine but will not provide the ratio of how much of that power/fuel is used to turn the compressor, as some fuel will be used to spin the compressor and some will be to produce engine thrust.
I didn't think this would be so hard to understand? I've wore myself out on google and cannot find this anywhere.
RE: Converting HP to thrust with a jet engine.... A motor jet estimation?
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Converting HP to thrust with a jet engine.... A motor jet estimation?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Converting HP to thrust with a jet engine.... A motor jet estimation?
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Converting HP to thrust with a jet engine.... A motor jet estimation?
Or any documentation for existing motor-jet engines would be good.
Thanks,
VS
RE: Converting HP to thrust with a jet engine.... A motor jet estimation?