Understanding and calculating exhaust thrust

In the original brochure for the RLM from Blohm & Voss on the BV-P 170, the data sheet on the engine power of the BMW 801 D also shows the exhaust thrust in connection with power selection and altitude.

S Abgas stands for Schub Abgas = Exhaust thrust in kg (= kp = kilopond)
PS = hp

Last paragraph: The increase in performance by utilizing the dynamic pressure is included in the calculation; the fan power (120 hp / 50 hp) is deducted.
 

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Basil said:
In the original brochure for the RLM from Blohm & Voss on the BV-P 170, the data sheet on the engine power of the BMW 801 D also shows the exhaust thrust in connection with power selection and altitude.
Click to expand...

Is that brochure freely available?
 
tomo pauk said:
Is that brochure freely available?
Click to expand...
These are reprints from the original brochures. I have bought mine a long time ago and it seems they are still available (now as used).
Search the internet for Luftfahrt Dokumente by Pawlas Verlag and you will find the RLM brochures for several Blohm & Voss and Focke Wulf late war projects (like the BV-P 215). They are red A4 softcovers and some have larger fold out original three views with different armament configurations in them.
 
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Aerospike exhaust nozzle:

As mentioned earlier, the very unsteady exhaust flow (refering to pressure, temperature, mass flow) and the highly variant athmospheric pressure and and aircraft speed makes it inpossible to find a perfect Laval nozzle for all operation point. However, there is an alternative to the Laval Nozzle and that's the beloved Aerospike. An Aerospike type nozzle can adapt to different pressure ratios much better than a Laval nozzle because of its expansion ratio adaptes to the pressure ratio.

The Aerospike design wasn't allready invented during WW2 and I've never seen it applied to an exhaust stack, but it could surly increase thrust, at least under most cicumstances. It might have been more difficult to implement on an inline engine than on a radial engine, but its intresting to figure out, how this might have looked like.

Unfortunately, with the end of the Unlimited Class at Reno, there is no usefull application of this idea anymore...
 
Nicknick said:
Aerospike exhaust nozzle:

As mentioned earlier, the very unsteady exhaust flow (refering to pressure, temperature, mass flow) and the highly variant athmospheric pressure and and aircraft speed makes it inpossible to find a perfect Laval nozzle for all operation point. However, there is an alternative to the Laval Nozzle and that's the beloved Aerospike. An Aerospike type nozzle can adapt to different pressure ratios much better than a Laval nozzle because of its expansion ratio adaptes to the pressure ratio.

The Aerospike design wasn't allready invented during WW2 and I've never seen it applied to an exhaust stack, but it could surly increase thrust, at least under most cicumstances. It might have been more difficult to implement on an inline engine than on a radial engine, but its intresting to figure out, how this might have looked like.

Unfortunately, with the end of the Unlimited Class at Reno, there is no usefull application of this idea anymore...
Click to expand...
I'm hearing rumblings about Wyoming hosting the races. Will certainly add an aerospike to the list of ideas for my lottery dream of a new Pond Racer.
 
When you are building you pond racer, I would like to support the engineering :)

Would be great if these races will be continued, I allways wanted to go there and simply waited to long....
 

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