Dream plane

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craigv
Posts: 9
Joined: Tue Sep 13, 2016 9:59 pm
Location: Alameda, CA

Re: Dream plane

Postby craigv » Fri Sep 16, 2016 12:36 am

My plane is an Aerospool Dynamic WT9 built in Slovakia. Here's a Wiki link to get an idea: https://en.m.wikipedia.org/wiki/Aerospool_WT9_Dynamic
I bought it used last November and had to do some work on it although not the airframe. It's much more popular in Europe where it often has retractable gear. Mine is an LSA and so isn't retract of course.

The weight is 670 pounds as shown by the official paperwork when it was bought. Wiki shows it as 660 pounds in non-retractable and no parachute. I'm 6'3", 220# and this is VERY comfortable for me.

I decided I wanted to set this up for economical touring so Wide Open Throttle is about 5400 RPM, replaced the Sensinich Prop with a Duc (gained 12 MPH) and a couple other things. What might have made the biggest difference in economy was this 912 ULS has manual fuel mixture (and standard carbs).

Today I flew back from Albuquerque to the San Francisco Bay Area (KAEG-KLVK, about 950 SM) and so was recording more of this information. Typically when I fly a distance I go to about 9500' and lean out the engine above 6000'. Flying to Albuquerque last week took two days due to the turbulence. So over two days including warming up the engine, take offs landings, etc., I flew at either 9500' or 11,500' (crossed the Techachapi's by Bakersfield and the Rockies at Flagstaff.). 4850-4900 RPM, 111-115 KTAS and 3.8 GPH.

Earlier this year I did a trip to the Tucson, AZ area (730 SM, KLVK-KAVQ) and kept it nailed at 4850 RPM as best I could. Again, including engine warm ups and everything...the total of all gas used to refill the gas tanks. 4850 RPM, 111 KTAS, 3.49 GPH.

The MTOW here in the US is 1212 pounds. The exact same aircraft in most of Europe is 600 KG or 1323 pounds. In the UK they made changes to fit under the 450 KG Microlight limitation. I don't remember what countries but some have a 1450 pound limitation for the exact same aircraft. This is a very robust, amazing handling beauty.
Sorry for the long commercial.

roger lee
Posts: 751
Joined: Tue Dec 08, 2009 11:47 am
Location: Tucson, Az. Ryan Airfield (KRYN)

Re: Dream plane

Postby roger lee » Fri Sep 16, 2016 9:39 am

Hi Craig,

Is this an ELSA or SLSA? If it is an SLSA you can't change the prop or anything else without an LOA from the aircraft MFG.
I did a big prop research project about 3 years ago. About 14 different props. For the fixed pitch on a 912 the determining factor is rpm for performance. If all you can get is 5400 rpm at WOT then you are over pitched. Over pitching has NO redeeming qualities. It cost climb, speed, fuel and higher engine temps. Plus extra stress on the engine. The mid 2006 model engine and earlier could even crack the case. Under pitching gives you better climb, but you loose fuel economy and cruise speed. The sweet spot for rpm for our fixed pitch props is 5600 - 5650. This gets the BEST BALANCED performance for all the above parameters. The engine was also not designed to run in the 4K rpm range for extend cruise. It is designed to be run in the 5K range. Most seem to like 5100-5400 rpm for cruise. 5200 seems to be a break point for speed, fuel economy and speed, but you can check that on your own and this is predicated on having a 5600-5650 WOT pitch setting. When I tested all those props all MFG's would tell you their prop is the best thing since sliced bread. Many people who change props and swear by speed gains are because of rpm at WOT differences (pitch) and the fact that when they flew each prop was on different days under different atmospheric conditions and no pilot is exactly the same every time.
When I did all my research I had 4 identical except planes that were MFG within a couple months of each other and I set up for pitch to make them equal and we would take off in pairs side by side and all would fly size by side in the air. Take off and flight procedures were as controlled as possible. It's the only test like it I think in the US. So many of the variables were removed from a normal individual test.
Bottom line RPM is absolutely the deciding factor and for the most part all props are equal. Any big differences from one to another are pilot and atmospheric condition caused and some wishful thinking.
If you had another identical plane like yours and their WOT rpm was set to 5600-5650 they would out climb you, go faster, get better fuel economy and have lower engine temps and less likely to hurt the engine.

Set your WOT to 5600-5650 in level flight and your AVERAGE altitude. Prop pitch can be different for a guy in Florida that never goes over 2K' vs a guy that lives on Colorado and always flys at 10K'.

Your engine has to have the HP and torque to turn a prop and over pitcher no just hinders that.
Roger Lee
Tucson, Az.
LSRM-A, Rotax Instructor & Rotax IRC
(520) 574-1080 (Home) Try Home First.
(520) 349-7056 (Cell)

craigv
Posts: 9
Joined: Tue Sep 13, 2016 9:59 pm
Location: Alameda, CA

Re: Dream plane

Postby craigv » Fri Sep 16, 2016 12:56 pm

Hi Roger - Thank you for your through response and the conversational tone. Much appreciated.

Yes, my Dynamic is an SLSA and the Duc Swirl is an approved prop.

Much of my information is from people in the business in Europe and the U.K. My limited personal prop tests support your much more complete tests, in that there is not much difference between props. In the UK and Europe many folks have switched over to the Duc Swirl prop as it does seem to make a difference. They claim it "flexes", thus changing shape much more than most props as it spins. I don't know if that's true or not but we tried to make that carbon fiber Sensenich prop better and couldn't. The Swirl made a dramatic improvement from the first flight. The word I've gotten is that the Duc Windspool prop, although it looks better than the Swirl, performs like all the rest.

Everything I've read about Rotax engine RPM's support exactly what you have said...I've even heard Eric Tucker say these things. In the UK there are more Microlight aircraft in schools and clubs than what we have here and many of these aircraft (and engines) have ALOT of hours. Some of these Rotax engines are set up exactly as I have described here and as of a couple years ago some were well over 4000 hours and are probably over 5000 hours now. I realize this is against standard doctrine but I'm willing to be a guinnea pig here in this test to get the results I reported.

3Dreaming
Posts: 2401
Joined: Sun Jan 10, 2010 6:13 pm
Location: noble, IL USA

Re: Dream plane

Postby 3Dreaming » Fri Sep 16, 2016 2:17 pm

Craig,

Please be aware that just because the prop is approved that you can't just put it on. You are still required to record the change to the airplane with the manufacture. It is a ASTM requirement that records be kept on all changes to the airplane since it was built.

I am with Roger in that the pitch should be decreased and RPM increased. In Europe they often have sound issues that we don't have here, and that could be the reason they try to keep the RPM low.

MackAttack
Posts: 145
Joined: Wed Apr 20, 2016 10:22 pm

Re: Dream plane

Postby MackAttack » Sat Sep 17, 2016 9:59 am

Nice airplane!!! I have the Sensenich on my Tecnam LSA and like it so far but was actually thinking about trying the Duc as an option to get a few more knots of speed in cruise... I can get an LOA for it, but have heard that the Duc prop is not quite as smooth-running as the Sensenich - having said that, Bristell ships a lot of their LSAs with the Duc, so it may well depend on the particular airframe too. Would be very curious to know your precise numbers on RPM/cruise performance (and vibration/cockpit noise) once you get them all dialed in.

Thanks!

roger lee
Posts: 751
Joined: Tue Dec 08, 2009 11:47 am
Location: Tucson, Az. Ryan Airfield (KRYN)

Re: Dream plane

Postby roger lee » Sat Sep 17, 2016 2:57 pm

Every prop Mfg and prop owner will always tell you how great their prop is. Bottom line after all the testing and research it just isn't there.

The only prop I did have some performance issues with was a Warp Drive in climb. I'm sure it is the flatter design. Once in cruise it was fine.
Roger Lee
Tucson, Az.
LSRM-A, Rotax Instructor & Rotax IRC
(520) 574-1080 (Home) Try Home First.
(520) 349-7056 (Cell)

craigv
Posts: 9
Joined: Tue Sep 13, 2016 9:59 pm
Location: Alameda, CA

Re: Dream plane

Postby craigv » Sat Sep 17, 2016 7:28 pm

Mac - Two aircraft ago I started researching props looking for something that might work better. Research showed pretty much what Roger reports but with a little more variation...but essentially little to no difference between props. An enormously experienced Microlight mechanic that I know from the UK said pretty much the same thing, except the one prop he found that made a difference is the Duc Swirl (not the Windspoon).

The aircraft I had prior to this one was a Aerotrek and I installed the Duc when I bought it (with an LOA). It's smooth and of normal noise..certainly quieter than the two blade Sensenich that was on my current Dynamic when I bought it. I was very happy with the Swirl but didn't have anything to compare it to.

Last November I bought my current Dynamic and there were several issues. I didn't want to replace the Sensenich due to the costs but we fiddled and futzed over a few months with it and couldn't get it up to speed or smoothed out. We did not try to balance it. I was frustrated and so got an LOA and we installed the Swirl. Remarkable difference! Would it have worked out if we balanced the Sensenich? I don't know but I'm thrilled with the difference. I never recommend to someone to change out their prop, I only tell my story.

This morning I went for a flight in smooth air for a couple runs: WOT - 5480 RPM, 1000', 127 KTAS, 76 degrees F. It does make me wonder how fast it would go at 5800 RPM.

The reports I made earlier show my cruising speeds between 9500' and 11,500' and engine leaned out.
4850 RPM, 111KTAS, 3.49 GPH on an over 700 mile flight.
4850 - 4950 RPM, 111 - 115KTAS, 3.8 GPH on a 950 mile flight.

I get KTAS using the Utilities on WingX Pro.
Last edited by craigv on Sat Sep 17, 2016 11:56 pm, edited 3 times in total.

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dstclair
Posts: 1037
Joined: Thu Mar 06, 2008 11:23 am
Location: Allen, TX

Re: Dream plane

Postby dstclair » Sat Sep 17, 2016 9:33 pm

I think I posted this earlier but I replaced a Woodcomp prop with a Duc Swirl on my Sting and got very good results. I took careful readings with my old prop flying to KORK to get the new prop. I took the same readings with the Duc returning homw. At a density altitude of 7100, I got an 8kt increase in TAS at 5100, 5250 and 5400 rpm.
dave

MackAttack
Posts: 145
Joined: Wed Apr 20, 2016 10:22 pm

Re: Dream plane

Postby MackAttack » Sat Sep 17, 2016 10:00 pm

Very interesting reports guys, thanks! I have the 3-blade, ground adjustable, composite Sensensich ... Top of the green line with my 914 Tecnam Astore is 5400 rpm ... I hope to be able to test props here later this fall. When I communicated with Duc, they recommended the Flash rather than the Swirl, which is interesting. Will report back ...

I'm not surprised

Cheers!

rgstubbsjr
Posts: 101
Joined: Fri May 02, 2014 5:54 pm
Location: GBR - Great Barrington, MA

Re: Dream plane

Postby rgstubbsjr » Sun Sep 18, 2016 9:05 pm

I've flown 12 different SLSA\ELSA types. Old certifieds, seaplanes\amphibs, tail draggers, powered gliders, brand new low and high wings.
My dream machine, my personal, all-time favorite, is the Arion LS-1 Lightning. It does everything I want it to do, everything I need it to do, and it does it with panache.
It's a hot rod, and can do mild aerobatics without me worrying about the wings or tail coming off.
As soon as I can swing it, I'm going to order one.

av8rshane
Posts: 1
Joined: Fri Oct 19, 2018 11:49 am

Re: Dream plane

Postby av8rshane » Fri Oct 19, 2018 11:55 am

craigv wrote:My plane is an Aerospool Dynamic WT9 built in Slovakia. Here's a Wiki link to get an idea: https://en.m.wikipedia.org/wiki/Aerospool_WT9_Dynamic
I bought it used last November and had to do some work on it although not the airframe. It's much more popular in Europe where it often has retractable gear. Mine is an LSA and so isn't retract of course.

The weight is 670 pounds as shown by the official paperwork when it was bought. Wiki shows it as 660 pounds in non-retractable and no parachute. I'm 6'3", 220# and this is VERY comfortable for me.

I decided I wanted to set this up for economical touring so Wide Open Throttle is about 5400 RPM, replaced the Sensinich Prop with a Duc (gained 12 MPH) and a couple other things. What might have made the biggest difference in economy was this 912 ULS has manual fuel mixture (and standard carbs).

Today I flew back from Albuquerque to the San Francisco Bay Area (KAEG-KLVK, about 950 SM) and so was recording more of this information. Typically when I fly a distance I go to about 9500' and lean out the engine above 6000'. Flying to Albuquerque last week took two days due to the turbulence. So over two days including warming up the engine, take offs landings, etc., I flew at either 9500' or 11,500' (crossed the Techachapi's by Bakersfield and the Rockies at Flagstaff.). 4850-4900 RPM, 111-115 KTAS and 3.8 GPH.

Earlier this year I did a trip to the Tucson, AZ area (730 SM, KLVK-KAVQ) and kept it nailed at 4850 RPM as best I could. Again, including engine warm ups and everything...the total of all gas used to refill the gas tanks. 4850 RPM, 111 KTAS, 3.49 GPH.

The MTOW here in the US is 1212 pounds. The exact same aircraft in most of Europe is 600 KG or 1323 pounds. In the UK they made changes to fit under the 450 KG Microlight limitation. I don't remember what countries but some have a 1450 pound limitation for the exact same aircraft. This is a very robust, amazing handling beauty.
Sorry for the long commercial.


Hey craig i’m buying a wt9 right now!! when i get it i’d love to meet up!!! Where are you located? hope to meet soon.


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