inflight adjustable props.

[tiketyboo]

anyone out there had experience with inflight adjustable props particularly on rotax 912's, would love to hear of your experiences.

 

in talking with engineers i am led to believe we need one setting for one temperature and humidity and at each change in temperature and humidity you need another setting so having a fixed pitched prop is not really the best solution for flying in changing weather like here in Ontario.

 

if the temperature is cold and dry you are trying to move a lot more weight and air than when the temperature and humidity is high. so to make your plane work well you need to change your pitch to meet the type of air you are in. makes sense to me.

 

i have googled this subject but did not find much information.

 

i have a 912 rotax on a jk 05 pathmaker, she flies well but you know how it is, i want it better.

 

 

[Russ]

Know of 3 flyers with them.........2 on gyros, all 3 love them. Downside...$$$$$$

 

 

[farri]

anyone out there had experience with inflight adjustable props .

Hi tiketyboo,Yeah, I`ve had one experience with an inflight adjustable prop and it wasn`t real good.

 

I was a passenger in a Drifter,powered by a Rotax 582 with an electroniclly inflight adjustable prop, the prop hadn`t been on long and the pilot was still getting used to using it.

 

We took off,in the middle of a hot day, from a field at 3000 feet AMSL and almost got wiped out because the pilot had forgoten to adjust the prop correctly on takeoff,too coarse a pitch was set on the prop,Closest call I`ve had in 25 years of flying,I know this wasn`t the fault of the prop,it was the fault of the pilot.

 

If the Prop doesn`t fail and it`s used correctly, it should be superior to a fixed pitch Prop,regardles of global position..

 

Cheers,

 

Frank.

 

 

[facthunter]

In Flight adjustable props.

 

You can get a bit academic with this subject. (going into air density, which is more affected by altitude than anything else).

 

The main reason variable pitch props are used is speed range. You can get a bit more grunt at the slow end and a bit more speed at the fast end, with a variable pitch prop. The amount depends on the aircraft characteristics.

 

If you looked at the problems associated with certified props relating to harmonics, you would freak out with the idea of using an uncertified one, but many do.

 

The downside is WEIGHT, COST, RELIABILITY, COMPLEXITY. If you have a hollow driveshaft, (ROTAX), the control is simplified and you can use a mechanical linkage. (Some have exhibited a tendency to surge slightly,(RPM's) due to play in the linkage. Nev

 

 

[HEON]

I currently have in flight adjustable props on two of my three aircraft. Rearly could not see the need on a 912 powered Drifter as I can exceed Vne on ground adjustable in level flight!

 

I cannot think of a more cost effective solution to increase ones cruising speed in any aircraft. In UL/LSA aircraft around 10% increase the norm.

 

With Rotax engines a 914 over a 912 will not give this percentage increase (at least in the 914 aircraft I own), and cost over double the price. I think other solutions would also cost more, or impose cabin size issues.

 

Currently importing an amphibian into Australia and an inflight adjustable prop turns it from a 85kt to 95kt cruise aircraft which is even better. I have, and will, continue to recommend this option as one of the best to be fitted from the available list. I personally think more use than Dynons, auto pilot, or BRS if total price is of importance.

 

Pre jets, nearly all passenger aircraft post 1930's had adjustable props. The risks must have been less than the advantages.

 

As for problems, anything mechanical can break, however all in flight adjustables I know are designed to go to fine pitch which allows reduced speed flight and safe landings.

 

 

[Guest Maj Millard]

I have experience with the Airmaster in flight/constant-speed props, and they are a nice unit allround...but costly=$$$$.

 

Also have flown with the manual (hydrylic) Indavario props which don't do too bad either. Cheaper than the Airmaster but a bit trickier to set up/adjust. Both do well on the 912 engines which they are designed for..................................................Maj

 

 

[farri]

I currently run a Rotax 503, driving an E type gearbox,with a 3 blade 60 inch Ivo, ground adjustable prop and I`m as satisfied as I reckon I can be with this combination, I`ve been able to set the pitch to an acceptable average.

 

I say average because the efficiency of a prop depends on air density and the power of the motor to drive that prop.

 

Being satisfied with the performance,I`m not going to reset the pitch every time I go flying,however,I can do so if required. :thumb_up:

 

Cheers,

 

Frank.

 

 

[facthunter]

Sorry B.R.for the delay. I have seen several persons fit ground adjustable props to Gazelle's. After fiddling with them ALL went back to the original prop. IF you can get a propeller which in the first place is proven to work on your particular aircraft, you are fortunate, but if you have a rare model or version, you might be able to justify getting the adjustable prop.so you can adapt it's settings.

 

Your motor must reach the right RPM on take-off to get the power that it is supposed to develop. IF it is under revving them you are down on power.

 

Aircraft taking off from water have a high drag situation till the aircraft is planing so a CS prop would be a definate advantage there.. It is understandable that people want to get a bit extra from their plane, but if it is a fairly draggy machine any speed increase requires a LOT more power. If your plane staggers along when it is at high weights, or won't get to altitude on a hot day, it needs more power ,and/or a bigger wing.. Nev

 

 

[Russ]

Check out the "Ivo" props. ( fixed and variable modes ) they also cater for all HP's.

 

12v powered. ( dear as poison tho )

 

 

[Guest burty]

We have 912 with after market fitted Idrovari variable pitch with hydraulic control, it takes very little movement on controller to get required pitch,works well. Local LAME warned against electric versions as micro switches stick and cause problems.

 

 

[Russ]

Had a $4000 "LG" latest tv go feral recently...........they replaced it ina blink.......does that mean "LG" is a product not to touch...............I don't think so.

 

"Branding" as your "lame" has done is bunkam. Truth be known, he just needed to make a noise. For sure, sometimes a "thing" will defect..........but don't label them all as cr*p

 

Following along your line, all jabaru's should be grounded then.......i don't think so.

 

 

[Russ]

Mine............"Ivo" magnum, 74" x 3 blader, leading edge protected, manually set your pitch in flite, or............set what prop revs you want then the constant speed governor takes control.

 

If.............if, a fault occurs, the current pitch set remains.

 

landed Oz...............$4000

 

( magnum 74 +++ is for higher HP engines, 2 other choices avail for lesser HP engines)

 

am hearing reports guys fitting smaller diam magnums to 912 and 914's with good results.

 

Costings of other makers avail.......?????