Cruise power?

[Duncan]

Hi,
The new engine sounds really superb.  I note, however, that it has been de-tuned to 165hp, by limiting the max RPM - among other things, no doubt.  I certainly don't have a problem with this, but I was thinking that if this de-tuning is accomplished by limiting the RPM, does this mean that the engine can be flown at full power, since it will only be (effectively) revving at about 70% of max anyway?

Regards,
Duncan

[BAZMAY]

Hi Duncan,
The rotary will sing happily all day at the revs we are using, however the main consideration ( at least to me ) is the fuel burn when at full throttle.  Of course cooling is a consideration as well, but since wrapping the exhaust temps have been excellent.
I now have a testing program I will use to collate rpm against speed, and fuel burn/hour at various pitch settings. Both Tom and Jon Johanson have suggested this.
I hope to finish up with a placard in the cockpit similar to GA aircraft with CS props.

Cheers
Baz

[peterlovell]

Hi Baz,
Does this mean you have a prop pitch indicator?
If yes , could you explain a little about it,
thanks, Peter

[BAZMAY]

G'day Peter,
No, I don't have any indicator but I have put a line on the adjustment knob in the cockpit and when I start testing the first setting will be with no turns ( finest setting ), then 5 full turns, 10 full turns etc.
As I go through the rev range in 200 rpm incriments at each prop setting I will also note fuel flow and eventually finish up with a chart that can be placarded in the cockpit. It will probably take a while to get all the information.

I intend to go through a rev range from 4000rpm to 5000rpm.  After that I might find it necessary to extend both rev range and also the number of turns of the prop setting knob.

Hope this makes sense, hard to explain.

Baz

[peterlovell]

hi Baz,
that makes perfect sense - I will be interested to hear the results
mine runs on a toggle switch -- the only way of knowing the adjustment is to ttime how long the switch is held on for.not exactly easy but will give it a go when i get back
cheers peter

[mark jones]

This is interesting. Does the pitch control rely on a potentiometer seting? If it does then it woudn't take too much to rig up  readout using the resistance value as an indicator. Also, once a good setting is worked out you could rig up a system to set for takeoff, climb and cruise. Then all you would need is to have a rotary ( ) switch to dial up the required pitch setting.

[av8r]

No the system has no potentiometer for the use of the pitch control, but having a thought last night heres one way to make an indicator that I used for flaps in the past , it goes like this.

Take a VDO fuel GAuGE and Sender , mount the sender so that it can be moved through the sweep range to the stop pin on the pump the gauge will then move foward and aft depending where the pump is wound into you can actually get the gauges apart and have them re-named and the scale changed as well then you have a cheap purpose built system to tell you where the pump is and a close to the prop setting .

Give me a call if its a bit hard to work out always here , Tommy

[garrymodes]

Just trying to find max. rpm for long journeys safely with my four times. Were told in 4500 to WOT with their mischief. My local Yamaha Mech. I said WOT would not hurt them. Honda dealer said 80% of WOT. Another genius. indicated that 70% of WOT. I want to make my travel 85 miles faster than I can not put my engines. The specification Honda 150. at full speed is 5000-6000 rpm. My WOT is 5400 rpm. AMI works for reproping 5800-6000 WOT.