Hi all,

What kind of thrust would you expect to get from an 1834cc VW?

What kind of thrust would you expect to get from an 1834cc VW?

You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser.

You should upgrade or use an alternative browser.

- Thread starter Twodeaddogs
- Start date

Hi all,

What kind of thrust would you expect to get from an 1834cc VW?

What kind of thrust would you expect to get from an 1834cc VW?

Thrust is determined by pitch, number of blades, and diameter of the prop, not by the horsepower.

So if I put a Spitfire prop on a VW, I get the same thrust? Cool! Same pitch, number of blades, and diameter of the prop, right?

I think you're bending the laws of physics with that statement.

At what airspeed and maximum prop diameter? The airspeed matters a lot.Hi all,

What kind of thrust would you expect to get from an 1834cc VW?

Maybe I should have also said "RPM" in that sentence but I did mention that you need an appropriate prop for the engine a bit later.So if I put a Spitfire prop on a VW, I get the same thrust? Cool! Same pitch, number of blades, and diameter of the prop, right?

I think you're bending the laws of physics with that statement.

typical 57 to 60 inch prop for 3400 rpm?

1835 cc, 94 mph.

Dan

Dan

From there, you can do all sorts of calculations and get a better "real" number.

Assumptions: SL, std day. 60 HP, 3400 RPM. Two-bladed wood prop with a pitch optimized for the given airspeed (so, the same prop won't produce all the numbers shown below). Prop diameter chosen to keep tip speeds below 880 FPM and reasonable camber ratios.

Airspeed.....Pitch....Diam............Est. Thrust

50 MPH........22.2".....59".................249 lbs

60 MPH .......24.4".....58"................231 lbs

70 MPH .......26.7".....57"................213 lbs

80 MPH........29.1".....56"................198 lbs

90 MPH........31.7".....55"................184 lbs

100 MPH.....34.6".....55"................172 lbs

110 MPH.....37.5".....54".................160 lbs

120 MPH.....40.5".....53".................150 lbs

130 MPH....43.7"......53".................141 lbs

Airspeed.....Pitch....Diam............Est. Thrust

50 MPH........22.2".....59".................249 lbs

60 MPH .......24.4".....58"................231 lbs

70 MPH .......26.7".....57"................213 lbs

80 MPH........29.1".....56"................198 lbs

90 MPH........31.7".....55"................184 lbs

100 MPH.....34.6".....55"................172 lbs

110 MPH.....37.5".....54".................160 lbs

120 MPH.....40.5".....53".................150 lbs

130 MPH....43.7"......53".................141 lbs

Last edited:

Didn't we just do this recently? ... Static thrust

Assumptions: SL, std day. 60 HP, 3400 RPM. Two-bladed wood prop with a pitch optimized for the given airspeed (so, the same prop won't produce all the numbers shown below). Prop diameter chosen to keep tip speeds below 880 FPM and reasonable camber ratios.

Airspeed.....Pitch....Diam............Est. Thrust

50 MPH........22.2".....59".................249 lbs

60 MPH .......24.4".....58"................231 lbs

70 MPH .......26.7".....57"................213 lbs

80 MPH........29.1".....56"................198 lbs

90 MPH........31.7".....55"................184 lbs

100 MPH.....34.6".....55"................172 lbs

110 MPH.....37.5".....54".................160 lbs

120 MPH.....40.5".....53".................150 lbs

130 MPH....43.7"......53".................141 lbs

Engine on the SSSC. 1835 cc, 60 HP, 3200 rpm at WOT @ 94 mph. Prop Culver 60" x 26" . Cruise at 2650/2700 rpm at 80 mph @ 3 GPH. ROC= 1200+ FPM.

I know that prop and engine combo has proven to be great for your SSSC. I'm guessing that the prop blades have quite a bit of camber to their airfoil if it gets you to 94 MPH with a 26" pitch. Sounds like it climbs great.Engine on the SSSC. 1835 cc, 60 HP, 3200 rpm at WOT @ 94 mph. Prop Culver 60" x 26" . Cruise at 2650/2700 rpm at 80 mph @ 3 GPH. ROC= 1200+ FPM.

I don't know about the pitch except its stamped 26" Could be different, I don't know. That climb of 1200/1250 fpm is at about 780 lbs.I know that prop and engine combo has proven to be great for your SSSC. I'm guessing that the prop blades have quite a bit of camber to their airfoil if it gets you to 94 MPH with a 26" pitch. Sounds like it climbs great.

Hi all,

What kind of thrust would you expect to get from an 1834cc VW?

If your aircraft has an expected climb/cruise speed of 20 mph, then secure it to a ground anchor with a load meter, apply full throttle and read the force indicated. What could be simpler?

Brian W

Running into the trees at the end of the runway while still in ground effect?If your aircraft has an expected climb/cruise speed of 20 mph, then secure it to a ground anchor with a load meter, apply full throttle and read the force indicated. What could be simpler?

Brian W

The thrust in cruise is same as the drag. So just shut off the engine and measure the airspeed and sink rate to calculate drag.What could be simpler?

If you want exact then remove the prop and tow it aloft. But who needs exact?

CAFE set up switches to measure end float on the crank. They could tweak the throttle for zero thrust.The thrust in cruise is same as the drag. So just shut off the engine and measure the airspeed and sink rate to calculate drag.

If you want exact then remove the prop and tow it aloft. But who needs exact?

With the original 'Clark Y' section propeller 60" x 32" on the Flitzer Z-1 prototype equipped with an 1834cc VW, it delivered some 150 lbs of thrust (from memory) with an Avoscale on a cable attached to the tailskid, using a Jaguar saloon as an anchor.

I took the propeller home and modified the section to approximate the USA 5 as a theoretical low drag section, rebalanced the propeller and the following weekend tested it again. This time it indicated 212 lbs of thrust and dragged the Jaguar across the grass, gradually accelerating throughout. I shut down to avoid colliding with a hangar, otherwise who knows how fast it would have gone (estimated 4 mph).

Current prop was pitched at 34" at the root and 32" at mid-diameter which holds the full throttle RPM to 3000 with no loss of maximum level speed (92 mph) or climb rate >700 fpm at typical load. I think the bullet cowl contributes to available thrust from closer to the hub. This theory is based on the experience of the Austro-Hungarian Luftstreitkraeft in WW1 when they removed the bowl spinners from their OAW Albatros 253-series fighters, cowling tightly around their Austrian-Daimler crankcases, to gain over 10 mph as a result.

This propeller was inadvertently cropped by about 2" following an incident with a deer which charged me on take-off. After trimming and rebalancing this has not appreciably affected performance, although I do intend to fit an optimal Hercules propeller in due course. The Flitzer Z-21 demonstrator for Hercules propellers allows full throttle operation during a continuous (+g) aerobatic sequence to be performed without overspeed, maintaining 3000 RPM throughout.

I took the propeller home and modified the section to approximate the USA 5 as a theoretical low drag section, rebalanced the propeller and the following weekend tested it again. This time it indicated 212 lbs of thrust and dragged the Jaguar across the grass, gradually accelerating throughout. I shut down to avoid colliding with a hangar, otherwise who knows how fast it would have gone (estimated 4 mph).

Current prop was pitched at 34" at the root and 32" at mid-diameter which holds the full throttle RPM to 3000 with no loss of maximum level speed (92 mph) or climb rate >700 fpm at typical load. I think the bullet cowl contributes to available thrust from closer to the hub. This theory is based on the experience of the Austro-Hungarian Luftstreitkraeft in WW1 when they removed the bowl spinners from their OAW Albatros 253-series fighters, cowling tightly around their Austrian-Daimler crankcases, to gain over 10 mph as a result.

This propeller was inadvertently cropped by about 2" following an incident with a deer which charged me on take-off. After trimming and rebalancing this has not appreciably affected performance, although I do intend to fit an optimal Hercules propeller in due course. The Flitzer Z-21 demonstrator for Hercules propellers allows full throttle operation during a continuous (+g) aerobatic sequence to be performed without overspeed, maintaining 3000 RPM throughout.

- Participate in both public and private conversations with people that share your interest
- Start new threads
- See less ads

Enter your email address to join:

Thank
you! Please check your email inbox to continue.

There's already a member associated with this email
address.
Please log in or retrieve your
password.

Already
a member? Click here to log in
Register today and take advantage of membership benefits.

Enter your email address to join:

Thank you! Please check your email inbox to continue.

There's already a member associated with this email address. Please log in or retrieve your password.

Already a member? Click here to log in