skippydiesel

Sorry had to attuned to Grandpa duties- I would be interested in the following:

RPM & estimated fuel consumption at:

100 knots

110 knots

120 knots

The Sabre's stall speed, max load (600 kg?) and your  ground role, climb/speed, comfortable cruise & top speed as experienced by you.

The manufactures POH stall , cruise and max speed.

Your comments on your propeller performance (befor the accident)

Thanks Rhtrudder - I am trying to get information on CS/IFA propeller suppliers/producst - see my conversation in Prop Selection

Rhtrudder - May I ask what brand & type of CS/In flight Adjust  propeller is fitted to your aircraft ?

Guys! Guys! I apologize if my tone has been a bit off and offence taken but really not one person has come close to answering my question's. (MASSIVE FRUSTRATION))

I have a constant speed propeller endorsement and some limited real word experience of the same. So I have at least a basic understanding of how they work. 

I have never optimised my existing ground adjustable prop for high speed or cruise - just not practical in my circumstances.

Yes RFguy I could relocate to my local airfield or a host of others both near & far, just to find out how fast she will go with the prop so adjusted.  I know it will probably true out at about 125 knots. This is not the question - the question is about CS propeller supplier/manufactures and their products.

The question is not about my aircrafts performance per say but the reputation of the CS prop (delivering the goods) that I may purchase & fit in a few months time - so far no answers.

I have tried to stimulate the conversation & keep it a little on track by posting data/information/costs, on a small number of propeller suppliers/products - got virtually 0 response.

I have asked about the merits and weights of electric versus hydraulic - 0 response.

To be fair there have been one or two who have come close to making a constructive criticism.

To finish on a positive note - the conversation has, in general been stimulating, even if not to the point.

Quite extraordinary! We are now getting to the end of page 4 of this conversation and as yet not one contributor has addressed my original questions.

So far the conversation has, for the most part been negative, tending to focus on the  poor cost to effective ratio of a CS propellers in this class of aircraft, rather than performance characteristics? 

There does not seem to be any knowledge as to the merits of hydraulic versus electric CS props OR why hydraulics seem to be considerably lighter?.

It would appear that the few who actually want to discuss CS props are of the opinion that I wish to improve my TO/Climb despite refuting that several times?

It seems no one can imagine a CS prop improving cruise speed?

My references, in the CS context, to the amazing work of Robin Austen enlists nothing much more than silence?

What collisions can be drawn from this:

• There is no member of this Forum, with a level of experience  that gives then the confidence to respond to the original and repeated question, recommend a supplier /product ?
• The "opinionated" would rather indulge in negative thread drift than give constructive advice  Or admit ignorance?

I am disappointed in the 'Brains Trust"

Thank you for your council Kasper - you have repeated all that I already know.

What I dont know is who supplies the best CS prop for my aircraft and objectives.

Are there no CS drivers out there, who wish to have their opinions aired in this Forum ?

1 minute ago, M61A1 said:

 

If you don't understand the merits of the CS pop, don't get one.

Its the relative merits of the suppliers and their offerings NOT the merits of CS props of which I am well versed in the theory and have some experience.

Some CS propeller suppliers have answered my letter of enquiry:

MT- Propeller:

·         The MTV-1-1A/170-51 Electric, Weight? Cost $16,606 Au

·          MTV-34-1-A/170-202 Hydraulic, Weight 7.5 kg Cost $13,700.00 Au

Comment: Both 2 blade configurations. Expensive. No rational or detailed information/photos, etc. CS prop must be returned to service shop at 600 hrs (?) I do not know the relative merits of electric versus hydraulic but do know that my Rotax will require modification ($$) to facilitate the hydraulic propeller.

Airmaster:

·         Originally AP332S fitted with blades WWR68W by Whirl Wind Weight 11.5 kg without controller, Cost $11,540

·         Revised AP420 with blades SNR70E by Sensenich. Weight, 9.1 kg without controller Cost $11,370

Comment:  Both are electric. AP33 -is a 3 blade & AP420 a 2 blade. Airmaster were very fast & professional in their response but left me a bit disquieted in their all to quick change to a 2-blade recommendation. CS props seem to be a bit on the heavy side. No suggested performance changes with CS. Bit odd that the 2 blade is almost the same price as the 3 – would have thought there would have been a more significant price difference.  At this stage pricing seems about mid-range for a CS Electric.

Helix- Carbon GmbH

Performance data using FK14 aircraft:

·         Comparing fixed 2 & 3 blade props with their hydraulic CS, H60A 1.75m R-SI-22-2, there was a +7 Knot improvement in climb and a - 5 Knot decrease in cruise (go figure).

·         No weights given or other details. Cost $10,826 – I have no idea if the controller comes with this.

So to date-

I am getting some feed back but its quite limited (other than price).

The MT-Proppeller hydraulic weight is very attractive even if the price is high.

Airmaster is still probably the leader, being local and all that.

Anyone care to expound on the relative merits of electric versus hydraulic and why one is so much lighter than the other.

1 hour ago, M61A1 said:

Then, I think that a CS prop is probably going to provide some benefit. 

The Rotax owner website recommends setting up for Max continuous (around 5500 RPM) at WOT straight and level.

If the Zephyr is a clean as you reckon, there may well be another 10 kts to be gained.

The only CS prop I have had a few hours behind is a 3 blade Airmaster in another slippery airframe. I think that it does a great deal for the aircraft. It gets full power on takeoff and climbout around 60 kts while knuckling down  with speeds over 130kts at times. It is also simple to operate and can be feathered in case of engine failure.

That is a bit subjective though, as in, If I had to spend $12k on one I might look to see what else I could do

MS1A1 - I understand all of what you have said my question are:

What reputable CS propeller suppliers are there out there

What are the relative merits of the above

On your comment "WOT 5500 RPM" - if I were to set my existing ground adjustable prop for this, I have no doubt that my high speed cruise would be in the vicinity of 125 knots (an improvement of about + 6 knots) BUT my take off role would be very much longer and my climb less - in my situation this puts my life at risk.

18 minutes ago, kasper said:

Your own post Several after mine shows it - stall speed around 40 is ONLY if flown solo ... therefore it’s only raaus possible if it were solo so much less than the 300kg possible load

 

So what are you saying - cause the stall speed may be at solo /minimal weight (not RAA 600 kg) the aircrafts performance is not truly gobsmacking ?????.

I am not  interested in trying for  SGS/SRS performance  - I would just like to maintain my existing TO/Climb, while having a bit more cruise (+10 knots would be nice/acceptable)

Yeah! The Dog! seems to be a very friendly mutt despite the  fearsome appearance.

Hi again Robin ; have just received costed recommendation from MT-Propeller; Very expensive at $16,600 for the electric CS. The hydraulic , at $13,700,  is still a bit above even the  most expensive electric alternative supplier.

Have you any comments on Hydraulic versus Electric ??

Both props are2 blade  MTV-1 -A . plus some other numbers & letters which may relate to hub type, not sure. No rational given for recommendation. No suggested performance figures. No explanation as to high cost or cost differences - have asked for all.

What little I know is that the hydraulic is very light at 7.5 KG including governor. Got nothing on the electric - dont even know what the slip ring arrangement or controller look like.

One MT plus is that they have a dealership/workshop at Bankstown NSW. Other than Airmaster in NZ, I dont know if any of the other LSA CS prop makers have "local" service provisions.

For those who dont read other areas of this Forum: Robin Austens Sonera2 VH-SRS:

Broadly speaking the SERA 173 specs and differences from a standard Sonerai 2 are as follows (all solo)

• Max continuous cruise speed 173 Kts

• All day everyday cruise speed 165 Kts (24”/4800rpm)

• Economy cruise - 160 Kt at 15.2 L/hr 

• Aerobatic +6G -5G

• VNE 180Kts (testing included full range flutter testing up to and including 200Kts)

• 300Kg empty - 600KG MTOW – 300Kg payload 

• RV10 cockpit dimensions - comfortable for 6’5” pilot, 6’2” PAX (Sonerai volume +67%)

• Centreline flying from front seat

• High strength crash resistant zone around pilot (2.5X FAR23 requirements)

• Airframe structural strength = Sonerai +25%  

• Airframe efficiency = Sonerai +72%

• Stall speed slightly less than Sonerai II (minimum solo 39Kts)

• 1250 NM range at 160 Kts 

• 1700 NM range at 100 Kts 

• Also comfortable at 70 or 80 Kt “loitering” speed

• Constant speed propeller with latest Sensenich high speed blades

• 23” prop clearance for gravel strips

• Full span (30 degrees deployment) electric flaperons

• Horizontal Stabiliser - electric inflight adjustable

• Rotax 912 reliability and operating costs

3 hours ago, M61A1 said:

Skippy....What RPM do you get at WOT takeoff and what RPM do you get at WOT straight and level?

 

Hi M61A1 - Never tried WOT in strait level - Waaay toooo scary seeing the RPM climb so quickly into the red. Take off, I get 5800 RPM  easy - never stay there for long , throttle back as soon as I get to 2000 ft. Static WOT is 5200 RPM @ my current prop settings.

See data attached:

Propeller Selection Info.docx

1 hour ago, kasper said:

But you are not comparing apples to apples.  The soneri that is the speedster is limited to 300kg for people and fuel - it is a single seater in effect. And it gets down to the Raaus stall area with full span electric flaperons.  And it’s damnably clean in particular the engine cooling etc.  

mid you have bugger all drag increase with speed increase then your advantage of cs over fixed is limited and the relatively low wing load at the 600kg mtow with full span flaps Means it’s really nothing like your aircraft in terms of lift n drag.
 

You limit yourself to a low wing load and get full span flaperons then your sort of comparing apples and apples.

Hi Kasper - Robin Austen's Sonerai 2 VH-SGS is the world speed record holder I quote from http://worldrecordplane.com/ :

 "carries 2 X 90Kgs (200lbs) people, 2 tents & sleeping bags, air mattresses, doonas, pillows etc and all personal belongings on 1000+ Nm trips. With 103 litres (27 USG) usable fuel, SGS can remain airborne for over 14 hrs and could fly across the entire mainland USA at its widest part with only 1 fuel stop."

A tad more than 300 kg dont you think?

Oh! and I am not comparing my aircraft with SGS or with SRS, his latest Sonerai development (& quit a bit further from the original Sonerai plans see this Forum, AU/NZ General Discussion, VH-SGS Sonerai II) just  pointing out that considerable improvements in cruise speed are possible, subject to airframe limitations

12 hours ago, M61A1 said:

What that means is that the Zephyr must be aerodynamically dirtier than you think.

The laws of physics remain....Increase thrust or reduce drag.

For something with a broad range of speed like your Zephyr the CS prop is likely to give some good gains. At which end, and how much you won't know until you try.

"dirtier than you think" - how so? my POH (which is conservative in all other specifications) says my aircraft can cruise at 124 knots but clearly not with a ground adjustable prop set for TO advantage.

I accept the laws of physics - if I didn't I would expect Robin Austen type performance. My modest + 10 knots in cruise is a clear understanding of this.

I never actually asked for a rational on the purchase of a CS prop - I know it is an extravagance, with little cost/effect justification (as is owning a LSA for recreational purposes) - what I asked for was feed back on the CS props in the market place (performance gains/ ease of maintenance/TBO/manufacturers support/etc) - something that the respondents seem unable/unwilling to impart.

All laws are there to be challenged -

Tell me how Robin Austen's Sonerai VH-SRS, can have a high speed cruise of 170 knots, an every day economy cruise of 160 knots and a stall speed of under 40 knots, all in a little  2 seat aircraft, powered by a Rotax 912 ULS, that can easily fit into RAA standards ?

His Sonerai is 50 -60 knots faster than my aircraft, is limited by the same power potential & fuel consumption constraints as mine. Sure his airframe may be optimised for efficiency/speed, the Zephyr is non to draggy by everyday standards either,  though not in the Sonerai class , so all I would like is a miserly extra 10 knots. Where is the problem?

As yet, not one contributor to this conversation has provided any constructive advise, regarding CS propeller suppliers and their products  - after all I did open with the "Hope I will get some great factual criticism to the following:"

4 hours ago, facthunter said:

IF you get your prop exactly correct for  cruise it will be better at cruise than an adjustable one is. ALL of the sea plane racers (Schneider Trophy) of the 30's had fixed pitch props and took off from water (with great difficulty due the large torque ) but went nearly 3 times the speed of what you are dealing with. A  C/S's is a compromise too.  

I understand fully but unlike a Schneider Trophy sea plans with  prop optimised for speed, that have an almost limitless take off run and can climb out very slowly (if desired) without fear of any obstructions,  I must perform a short field take off followed by a steep climb to minimise my already substantial risk.

Thanks Thruster - Certainly gives a tightwad like me cause to think again. My instinct, probably wrong, is that the main limiting factor is the airframe - assuming of course that the engine power is appropriate/adequate.

If you look at what Robin Austen has been able to achieve, with the same engine I use, it suggest to me that a meticulous clean up of the draggy bits ( anal attention to detail) will yield great incremental potential gains . However these gain can only be realised if the engine can translate its power into thrust over the speed range.  Robin's first Sonerai, VH-SGS, needed  the help of a CS prop to break World Records.

The 180 hp Tecnam power to weight ratio is lower than my aircraft and its climb rate a lot lower - is this an indicator of unused power potential?

With my existing prop/setting, I can just make about 120 knots @ 5500 rpm for a fuel burn of about 17 L/h - The POH max cruise is 124 knots. The low fuel consumption (if correct) indicates the engine may be lightly loaded  (potential for pitch coarsening) & the potential cruise suggest some  ruise performance increases may be possible.

Robin's aircraft  are about 50-60 knots faster than mine is today. I will be positively ecstatic if I achieve a 10 knot increase in econamy cruise.

9 hours ago, RFguy said:

Hi Yenn. seems to be a pretty common thing for the low wing LSA (minimum fuel CoG hazard) . 

Low wing LSA - (Min fuel CoG hazard) , as fuel tanks are often in wing  forward of the wing spar, and a long way forward of the seats and baggage.

High wing MAY have  a different issue at min fuel - MAY be nose heavy IF  the wing(+fuel) is behind the front seats.....and only pax no bags. (J230)

 

GA low wing normal and utility  aircraft I see the wing is often further back to promote better baggage +  load capability I guess. spar under the seat..

 

Where's the fuel in the RV4 wing ?

 

 

Cant comment on all or even most low wing aircraft but the few that I have encountered place the fuel (in wing or fuselage) so as to have minimal trim change with fuel load and those minimal changes (if any) are from a slightly forward (max fuel) condition to a neutral trim condition as consumption/flight progresses.

The little high wing Jabs, I did my GA/RAA conversion in, had the tank behind the seats, so depending on max fuel load trim, it is conceivable that they go from neutral to slightly nose down as the flight progresses.

Irrespective of the aircraft, its wing location high/low, I would expect the wing to be placed in the position that gives the aircraft the greatest stability over it design load/location (including fuel).

In RAA aircraft, where the crew weight make up the largest single weight variable,  I speculate it is their location which probably most influences the location fore/aft of the wing.

1 hour ago, R Austin said:

It’s hard to predict what effect a CS will have on your plane.

if your existing prop is really fine, then it will be all in cruise and top end. If it’s really coarse, then the improvements will be in TO and climb. 
it also depends on target cruise density altitude among other things. I’m pretty sure you understand that.
It can be calculated if you have accurate MP, RPM and density altitude for a particular max speed scenario now.
If you are running out of revs badly now, 10+ kts is quite plausible. 
Just don’t have enough info and don’t want you to have unrealistic expectations if you hand over your dough.

 

From memory, the Airmaster 2 blade uses a more expensive hub, perhaps milled from an exotic alloy or not as large a production run or something, and that offsets the blade saving.

 

I suspect most 10+ knots Cessna gained over the “all round” fixed pitched was in the U/C drag reduction. I’m estimating Maybe 70%.??.

This is why people like me talk at length with people like you and of course the propeller suppliers. When talking to a supplier, I like to not only get their recommendation but also their rational/justification. After all the best part of $12 k is not small change to a person like me. When no justification is forthcoming or the answers glib and possibly dismissive, I get a tad sceptical (do Airmaster read this Forum ?).

Attached is an information document I have prepared, after seeking information from a number of suppliers, to send to a potential CS Propeller Selection Info.docx Supplier

Thanks again ALL - I have been in touch with Kyle of Aviation Welding - at this stage he is most likely to get this stunningly lucrative contract but I do have two, admittedly unlikely, leads to follow up on befor committing my hard earned $$$$

I dont imagine I will be doing the welding. I describe my bush welding as sticking bits of metal together - no skill, no knowledge, no finesse. I was recently advised that when welding pipe/tube it is advisable to fill the tube with Argon - blew my mind!  I will purchase all the "stuff" and engage the services of a suitably qualified/experienced person.

Robin - When boarders are opened, there will always be a welcome for you at The Oaks. Just say the word !

Thanks Robin

FYI Cessna did have a 172 with CS prop & retractable undercarriage - I did my endorsements in one. The one I hired was pretty old and tired and looked it but even so it seemed to get of the ground faster, better climb out and if memory serves me right , capable of about +10 knots on the fixed pitch version (the POH said more ).

When the time comes and the decision to/not purchase is made it will be under the assumption that I can preserve my existing excellent TO performance, while expanding, by at least 10 knots my cruise speed. Anything less will be a decision not to purchase.

The Airmaster cost of 2 versus 3 blade CS is very close - this was a surprise to me. The only slightly cheaper.

Just to clarify - in your opinion the 3 blade is smoother and is slightly slower (1 knot) than the 2 blade - have I got it right?

Somehow this communication seems to have got out of wack !