Weight,Power,Prop,& Rotorblades

CLS447

Platinum Member
Joined
Oct 30, 2003
Messages
6,331
Location
Reading, PA
Aircraft
Air Command 503 & Air Command SxS /EJ2.5
Total Flight Time
Aprox 400 gyro
I am concerned. My new SxS is pretty much complete & test flown. I am very happy with everything except...POWER! Remember I am used to flying a very light 447 AC.

My climbouts leave me wanting more. When cutting back on the throttle during cruise , she sinks. My focus is now to make her more efficient.

According to some, The Prince prop put the Warp to shame. Joe Souza, who built my engine & redrive, originally recommended this prop also. I couldn't get him on the phone yesterday.Does anyone have Princes' phone #. I know it's a long wait , so I better start talkin' to him! This is an easy area to try & get perfomance increases , so I will start there.

My EA-81 appears to be doing it's best. I chose the 81 over the 22 & 25 due to less weight. I could spend alot of money trying to get more out of it or just decide to go with a larger engine right off the bat. Before I order a custom prop, I better make that decision first.

Weight.... I look at my machine & think.... Where can I trim weight?
There are just not many places in my mind.

Another area that is pretty easy to try to increase performance would obviously be the rotorblades. I am hoping to be able to test a set of Dragon Wings at ROC. Erie & Mike.... are you reading this? I think I would need a 27 or 28' set. I could save on shipping for sure!

How about rotor RPM's. With 10 gallons of fuel & a 100 lb concrete passenger, my blades are spinning between 290 & 310. This is about 150 lbs less than my expected max gross( I want more fuel & more pass. weight ). Does changing rotor speed (pitch) do anything for performance?

I also wonder if I bite the bullet & buy a 912s, What would my increases be due to the fact that the engine is lighter.

I hope we can all use me & my machine as a topic of alot of dicussion at ROC. I can't wait to see you all .

Does anyone have any input here & now? Help! My head is spinning. It could be the coffee.

They were test flying a 2 place trike last night. 2 people with a 503. Less than 100 yrd takeoffs & amazing climb...... It just makes me think!

Ron, please be gentle & try not to hurt my feelings. That is if you plan on test flying it. Oh, don't forget to bring scratch & dent money!
 
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After reducing prop pitch by one degree last night, I am getting 5160 on full power takeoff with 12 degrees of pitch. 68" 3- blade warp. Back it down to 4600 at cruise & I lose altitude.
 
Chris,

That is about the same with mine. I won't even put in full fuel just to keep the weight down. Then again I need to lose some weight (220#). What worries me is I spoke to an EA81 expert and he said anything above 4000 for engine rpm and you are running it too hard! It doesn't make sense? What are you seeing for CHT? EGT?

Like Ken Brock would always say, "rotorcraft are draggy, very draggy."
 
Randy, I always think of Ken & echo those same words.

I do not monitor CHT or EGT's I only watch water temps, which are running less than 180. My plugs are running at a very nice color.

Souza said 5200 is no problem.
 
Chris,

A little more info might help.

What is the empty weight of the aircraft, no fuel?
What is the Max gross?
What is your rotor span, and what kind of blades do you currently have?
What modifications have been done to the EA81 (Cams? Carbs?)?
What is your redrive ratio?
 
Max gross- 1200 lbs

Rotor blades- new Sport Rotors 28' x 8.5 cord

Engine & redrive- Joe Souza 110 HP EA-81 with 2.18-1 gearbox

Dry weight- have to check notes
 
Use the program of the ASRA: gyroperf.exe (not the excel version), enter your data with the "," decimal not the "."... So you can see what you can expect from your gyro, playing with some parameters...

https://www.asra.org.au/


You must be sure to have 4° aerodynamic pitch of the blade:
 

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Lead sled....

Lead sled....

Chris, maybe 30' blades might have been a better choice on your lead sled.

By the sound of it prop efficiency will not produce a dramatic improvement.

The ea series is lighter but not have the "grunt" hp. An 160 hp ej-25 SOHC might be the go, but I would be looking at increasing the rotor diameter.

I changed from a 582 to a 618 with electric start on my Air Command side X side trainer. The gross weight increased by 4% BUT the hp increased by 16%. The increase was quite noticable.

One of the cheapest ways to gain efficiency can be to increase the length of the hub bar. Not always possible due to rotor system design.

Good luck with that fine looking machine.

Aussie Paul. :)
 
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It seems there is something wrong with the ARSA program with your data!...???
 
How about rotor RPM's. With 10 gallons of fuel & a 100 lb concrete passenger, my blades are spinning between 290 & 310. This is about 150 lbs less than my expected max gross( I want more fuel & more pass. weight ). Does changing rotor speed (pitch) do anything for performance?

Chris,

That RRPM seems a little low.
Are the SportRotors pitch-adjustable?
Does Vanek recommend a particular RPM for that rotor diameter and gross wt.?
 
Mike, I plan on calling Vanek Mon. to discuss in great detail about what I should do. If 30' blades are what I need, then I guess DW's would be out of the question. Oh, yes, they are pitch adjustable.

Maybe this winter he could fit my hub up with 30' blades at a reduced price.

Paul, I think that I agree with you on the bigger blades. But this is what he recommended. I have room for 30's.

One problem.... Jim V. had an EA-81 on his training machine. Now he has upgraded to an EJ-22. He said he would never go back. What do you think he will recommend to me?

Thanks for the interest & comments......Keep em coming!
 
Even with a 30' rotor, the perf are marginal...the less expensive is to fly alone: take one seat off!....or you need a 30' rotor plus a 125hp (at least!...135 hp is better) engine, to fly at 1200lbs...
 
OK I'm not getting max anything but just to note I am flying a MZ202P that is 60 HP and at 700 pounds it flys OK. I will be at ROC you can see it fly I am fat 245. The gyro empty weight is 410. I only put in 6 gallons to fly around here that is about an hour.
2.88 gears with a 73' power fin prop. Max RPM 5700.
 
OK , I've been thinking about this all day while I was getting my ladder crane, like in the PRA mag, ready to help with blade removal & installation. For me this will be quite a bit of work hauling my baby down to ROC. I'm praying for nice weather.

I want to bring my Thrustbuster scale with to do some thrust testing. Sound like fun guys?

Paul, what blades were on your SxS trainer? What was gross weight? How is it that Larry B.'s heavier RAF flies fine with less measured thrust.

I've been warned about frontal drag. I can tell you that it is very real for me. I am thinking about some kind of fairing or partial enclosure of somekind to streamline it a little. Also, are Wheel pants really worth the weight?

Tim O.'s machine is similar to mine except it must be heavier. It has an EJ-22, Aux tanks & DW blades....27' I think. He's flyin OK but he also has an enclosure & more HP. With a 68" WArp the same as me , I would like to know how much thrust he makes. Isn't that really the important factor?

I will figure this out if I have to sell the farm, I'm in too deep already!

I just would like to get it right the second try!
What do I need? Longer blades? (more lift) More HP? (different engine) Better prop? (more thrust) Less drag (enclosure) Better blades? (Dragon Wings) More rotor speed?(change pitch)
Less weight?(diet & start drilling holes)
Tune in tommorrow for the answers to these & other questions! Or ... Tonight at 11 on Action news! Uh- oh... the Weyerbacher is kicking in.
 
Chris I will try to be gentle with ya! First off, I told you not to mess up that sweet single place like you did!!! Wink wink ;) Seriously I was very curious how your were going to end up doing, cause all along I had my doubts that the EA-81 was going to make enough power to fly two people with decent performance. On my old two place tandem with EJ-22 performance was not all that hot with two people... Pretty much had to fly it " balls to the wall " to stay in the sky. Climbing to altitude in the summer with that machine would peg the water temps. It had 29.5 foot Rotorhawks. But this is how most two places are, The only two places I have flown in that seemed to have plenty of power and didn't seemed taxed to fly two people were Steve McGowans Parsons and the two RAF's I have flown in.

I too agree with Mike G. that your rotor RPM seems too low. Alot lower than I would want it to be if it were mine.

I also don't think the 1200$ you will spend on the prince will be the end all fix for your problems. I think it will end up either being Turboed or Superchargered or time to look at a Rotax 914 or a Big Heavy EJ-22 or 25. Or if you want to go Two stroke a Hirth F-30 or maybe the new Inline 3 banger. the Hirths will give you the best power to weight, but then your flying a Hirth!!! Bottom line is I think it will need a better power to weight ratio.
 
Chris the latest Subaru engines coming into Oz are the ej-20s producing 134 hp and the latest ej-25 producing 167 hp for an extra couple of pounds weight. Bothe are SOHC.

The ej-22 is no longer made. I have used an ej-20 of 120 hp and it was certainly a little behind the 130hp ej-22. I can't wait to try the 134 hp ej-20 and the 167 hp ej-25!!!!!!!!!!!!!!!!!! LOL

Don Parham, am I off track here?

Aussie Paul.:)
 
As for those Trikes... Yes it does make me go Hmmm too. Small cheap fuel efficent engine, flying two fat butts, and still climbs like a Bandit! Trikes make a great platform for my favorite auto conversion engine - the Geo Metro 3 banger - and just like a gyro they can be quickly broken down and trailered to where ever you want to take it. AND a Brs parachute can be used..... What is it about spinning rotorblades that makes us stick with what we fly???? :)
 
Chris asked..

Chris asked..

"Paul, what blades were on your SxS trainer? What was gross weight?"

They were 27' McCuchens and the gross weight was 750 lbs.

I did over 1500 hours in this machine that started with a 532 with 60" prop and 25' McCuchens and ended up with 27' McCuchens blades with a 618 and a 68" prop. The thrust increase between the 582 with a 60" prop and the 582 with a 68" prop was 25 lbs. Similar Mceagle Tims findings in prop diameter.

Aussie Paul. :)
 
Paul,
I don't know if you are off track or not because I don't know what you are talking about. We only get the DOHC EJ20 turbocharged engine in the Impreza WRX which develops 227 hp. The new (2005) SOHC EJ25 engines for this country are rated at 168 hp, I think.

If you are talking about the weight difference between the EJ20 and EJ25 you are probably on track. I weighed an EJ22 and SOHC EJ25 and found only 5 pounds difference between the two. When it comes to thirty hp difference I would certainly pay a 5 pound weight penalty. BTW, I developed a smaller, light weight, aluminum crank pulley that saves almost 5 pounds over the stock unit and slows down the alternator by 24%.
 
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