Thrust testing

[hector46]

PG0tKm3YoVo&hl

[atters]

Looks like if you are going to be able to pull the SUV in the winter, your going to need more thrust....:p

[RussHudson]

And our survey said........:) ???

[hector46]

I would need just a tad more thrust and i could have pulled Vitara;).

Survey said a disappointing 105 ish lbs so not as large a gain as I'd hoped.

The previous set up was 15 degree pitch blocks, engine rpm 3180, prop rpm 1680 and 95 lbs thrust.

This time 16 degree pitch blocks, engine rpm 3220, prop rpm 1705 and 105lbs thrust.

According to the Ultraprop chart (which most people don't believe) I should be increasing the rpm rather than the pitch. This may be true as I obviously have more power going in to able to pull higher rpm with more pitch but not that much of a gain coming out with the present set up. Perhaps that's just the way it is!!!!!!

[John Robertson]

Try increasing pitch to 17 or 18. The higher the engine revs, the more power is being "wasted" in the lift fan - you may get better thrust at a lower engine RPM.

[hector46]

I may give those 17's a try. I'll wait for a calmer day if that's possible up here and for Stuart to finish picking the debris out of his ears, nose etc. I agree the fixed lift fan would absorb less power at less rpm and allow more to the prop, you can hear the lift fan distinctly in the video!!!!!!

If the engine were to drop to around 3100 with the 17's this would mean the engine producing around 1hp less. If the gain of reduced lift fan drag is greater than that amount then I am up on the deal! I do not know the power absorption difference of the lift fan though.

What I really want to know is Mr Hudson's thrust (hovercraft) amount???????????????

[RussHudson]

What I really want to know is Mr Hudson's thrust (hovercraft) amount???????????????

I'm working on it :o, as soon as I've put the new rudders on and new skirt (if i ever get round to making it !!) I'll be testing it so will let you know.
Someone has stolen all free time and accelerated the time between now and Loch Fyne to very little !!!

We might have to test it in Scotland .....

Russ..

[hector46]

"We might have to test it in Scotland .....

Russ.."


I have the scales and I'm sure we can find something heavy to attach it to :).

Steve

[Ian Brooks]

:D not long now :D