Gyro Vs. Helicopter Cruise Efficiency

Gyro_Kai

Senior Member
Joined
Nov 29, 2006
Messages
3,221
Location
near Frankfurt, Germany
Aircraft
MT-03, Calidus (rent)
Total Flight Time
about 150
Dennis Fetters stated, that the Mini 500 was more efficient with the same engine, than an aircommand.

Apparently the translation from push via autorotation into lift, as in a gyro, is more prone to loss, than putting the power directly into a forward tilted lift even with the tail-rotor taking some if it away.

Kai.
 

dcnblues

Newbie
Joined
Sep 2, 2012
Messages
35
Location
San Francisco
Total Flight Time
95
Wait a minute. We do have 75% for the Helo, from it's own flight manual.
- "fuel hour consumption at 75% of the maximum developed engine power: l/h 20" -(CH-7 KOMPRESS)

And I emailed the manufacturer and got this as well:

Here below you find the informations requested:

90 *MHP: 18 litres/hour
100 MPH: 20 litres/hour
over 100 MPH: 23 litres/hour

Clotilde Quinterno
CH-7 Heli-Sport
So, at 75% power, the Helo is moving at 100 mph.

I can't believe the fuel consumption graph isn't a basic part of marketing an aircraft. This should be a lot easier. Seems like the manufacturers are hiding uncomfortable facts about their designs. But we're getting closer - some more data points and we might be able to make our own graph, and really look at the two aircraft types next to each other.

- "Best range speed...130 km/h IAS
-Fuel flow at 130 km/h IAS...13 l/h"
-AutoGyro Calidus

Same engine, same general configuration:
Helo: 4.75 gph at 90 mph
Autogyro: 3.43 gph at 81 mph

This is really frustrating as we're so close to some useful data. I think it's just close any way you look at it. But we are left to wonder whether their fuel burn / speed graphs cross, with the Autogyro being better slow, and the helo better fast, or something different. Frustrating.
 

StanFoster

Active Member
Joined
Nov 16, 2003
Messages
16,895
Location
Paxton, Il
Aircraft
Helicycle N360SF
Total Flight Time
1250
I am sure there are speed ranges the gyro is more efficient at.....and the same with a helicopter. A helicopter will burn the same amount of fuel per hour hovering as it will flying 100 mph. Of course the miles per gallon hovering is astronomical .....but the smiles per gallon are also.

Its two different types of machines and efficiency has to have all things considered. Flying airport to airport....a gyro can do that very efficiently. But wonder if you wanted to fly from your home to another friends home.....then only the helicopter can do that. Its all what your mission is.


Stan
 

kolibri282

Active Member
Joined
Aug 2, 2009
Messages
2,822
Location
Duesseldorf
Helo: 4.75 gph at 90 mph
Autogyro: 3.43 gph at 81 mph
Great job, Ian, that you figured (or rather found) out the figures! Now we have a pretty good answer to your question,
since as the speeds are close we can apply the third power law (cube, as you correctly said) with confidence and it
works out like this:

90/81 = 1.1111

1.11111^3= 1.3717421125

3.43*1.3717421125 = 4.7050754458

So at 4.705 versus 4.75 the gyro wins in a photo finish ...;-)

I thought that a well designed gyro like the Calidus would be a close match in such a contest.
 
Last edited:

dcnblues

Newbie
Joined
Sep 2, 2012
Messages
35
Location
San Francisco
Total Flight Time
95
Yay! A conclusion! (that was an ironic 'yay')

I'd still like more data, and I'm guessing a refresh and update of this particular helo design might be able to put it ahead, and of course they could each evolve in design to be most efficient at cruise speed, but the simple truth is they're pretty damm close any way you cut it. I'm glad I bumped the thread as I've learned a lot. Thanks for all the great info.
 

dcnblues

Newbie
Joined
Sep 2, 2012
Messages
35
Location
San Francisco
Total Flight Time
95
I am sure there are speed ranges the gyro is more efficient at.....and the same with a helicopter. A helicopter will burn the same amount of fuel per hour hovering as it will flying 100 mph. Of course the miles per gallon hovering is astronomical .....but the smiles per gallon are also.

Its two different types of machines and efficiency has to have all things considered. Flying airport to airport....a gyro can do that very efficiently. But wonder if you wanted to fly from your home to another friends home.....then only the helicopter can do that. Its all what your mission is.


Stan
I don't disagree with anything you said, but my perspective is that they can be made to be less different. Which could get the autogyro closer to taking you from home to home. But that's a discussion for a different thread. Thanks.
 

Vance

Gyroplane CFI
Joined
Oct 30, 2003
Messages
15,876
Location
Nipomo,California
Aircraft
Givens Predator
Total Flight Time
2200+ in rotorcraft
In my opinion “rotorcraft efficiency” is an oxymoron.

In my opinion “rotorcraft efficiency” is an oxymoron.

In my experience the method of piloting is sufficiently different to defy comparison.

Our Lycoming IO-320 is holding up better in The Predator than the Lycoming O-320 in the Robinson22s that belong to a local school.

Our cruise speed is nearly identical.

The predator has a higher maximum takeoff weight (1400LBS vs. 1370LBS).

The Predator appears to me to have a significantly higher VNE (138mph vs. 118mph). I have flown near this VNE many times and it is relatively arbitrary compared to a VNE of a certified aircraft. I suspect The Predator’s VNE is much higher but mine is not.

19.2 gallons will get the Robinson just as far as The Predator’s 22 gallons unless I fly high. At 7,500 feet The Predator can fly some further than the Robinson’s 200 mile published range before she runs out of gas. Neither aircraft gets good gas mileage. In other words neither aircraft should be termed efficient.

I suspect the Predator has a higher CDA, AKA more drag.

The Robinson’s listed climb at 1,200 feet per minute is significantly higher than The Predator’s at gross weight, around 700 feet per minute. Solo I typically see 1,100 feet per minute.

Staying outside of the shaded area of the height/velocity chart the Robinson takes close to the same distance to clear a 50 foot obstacle. A maximum performance take off in a Robinson is significantly shorter than The Predator to clear a 50 foot obstacle.

In my experience published performance figures are often divergent from real world performance.

In my experience a pilot’s claims for performance while hangar flying may also be divergent from reality.

That is my best effort at comparing apples to oranges.

My conclusion is that if you are concerned with efficiency a fixed wing would be a much better choice.

Thank you, Vance
 

Attachments

Last edited:

ckurz7000

Senior Member
Joined
Nov 7, 2006
Messages
3,438
Location
Vienna
Aircraft
ArrowCopter
FWIW, the ArrowCopter will do 100 mph at 20 lph at full gross (560 kg). At 450 kg it will cruise at least 10 mph faster.

The gross weight also needs to be figured in because any aircraft will cruise faster ormuse less fuel at the same speed if weight is reduced.

-- Chris.
 

Rotor Rooter

Dave Jackson
Joined
Feb 23, 2004
Messages
2,835
Location
Yes
A short diversion from the interesting facts that are coming up.

A short diversion from the interesting facts that are coming up.

Stan brings up a very valid argument in that speed and fuel consumption are primarily of comparative interest when they are related to a 'trip' between to distinct locations; particularly if the departure location or the arrivial location does not have a 'runway'. :yo:

_____________________________

From 0 to 25 (approx.) mph the helicopter is obviously more efficient.
From 25 to perhaps 60 mph (in the bucket) the helicopter may be more efficient.

Perhaps at faster forward speeds the gyrocopter may be more efficient. Dennis F. has previously mentioned that a partial power of approximately 15% going mechanically to the rotor improves the efficiency of the gyrocopter. This is because the induced drag of the rotor is reduced.

For very fast forward flight, such as experienced by Sikorsky's two ABC craft, the drag of the rotors is what limits the forward speed. The drag on the retreating side is actually accelerating the rotors. The rotors and mast represent 60% of the drag.

Of course for all flight speeds above 40 to 60 mph the fixed wing is the most efficient. I wonder how efficient an airplane would be if it was flying with full flaps and just above its stall speed?


Dave
 

StanFoster

Active Member
Joined
Nov 16, 2003
Messages
16,895
Location
Paxton, Il
Aircraft
Helicycle N360SF
Total Flight Time
1250
Vance- While we are comparing apples to oranges with helicopters to gyros........your IO320 in both is is not apples to apples. The I0320 if I am correct is 160 horsepower ......but is derated to only 124 horsepower in an R22. We need to compare same horsepower .

I like the comparison which one can stay airborn the longest under 25 mph.....that would not be fair of course!


Stan
 

Stan V

Active Member
Joined
Jan 23, 2011
Messages
1,271
Location
Monticello, GA
Aircraft
Piper Arrow/RAF2000
Total Flight Time
450
I believe Vances IO230 is rated 160 hp at 2700 RPM, I know with this eng in a fixed wing/fixed pitch prop it won't achieve it's RPM , at least not at take off. A friend of mine recently sold his O360 180hp Grumman Tiger, again rated at 2700rpm, with the fixed prop he couldn't get but 2300rpm on take off. My Arrow with the IO360 180hp could achieve its rated HP anytime because of it's constant speed prop, Just like the R22 is capable of (I think). I'm wrong alot so would love to here a rebuttal, what do you think Vance.
 

WaspAir

Supreme Allied Gyro CFI
Joined
Oct 21, 2006
Messages
4,485
Location
Colorado front range
Aircraft
Bell 47G-3B-1 / A&S 18A / Phoebus C, etc.
Total Flight Time
stopped caring at 1000
I believe Vances IO230 is rated 160 hp at 2700 RPM, I know with this eng in a fixed wing/fixed pitch prop it won't achieve it's RPM , at least not at take off.
Cruise or climb prop?
 

Stan V

Active Member
Joined
Jan 23, 2011
Messages
1,271
Location
Monticello, GA
Aircraft
Piper Arrow/RAF2000
Total Flight Time
450
Good point, if Vances IO320 (I was dyslexic) has a climb prop he may see the rated HP but then couldn't compete with the R22 in cruise!
 

bryancobb

Junior Member
Joined
Aug 2, 2010
Messages
5,008
Location
Cartersville, GA
Aircraft
Owned Brantly B-2b/Fly Kitfox III/Mini-500b
Total Flight Time
1350
The only FUN-MACHINE that is less efficient than a Rotorcraft is a BOAT!
 

Vance

Gyroplane CFI
Joined
Oct 30, 2003
Messages
15,876
Location
Nipomo,California
Aircraft
Givens Predator
Total Flight Time
2200+ in rotorcraft
I love the book Stan V.

I love the book Stan V.

Hello Stan V, I love the book.

I do not ever compete with a Robinson 22 on any level.

The local helicopter school has two Robinson 22s with a Lycoming O-320 A2B. They have trouble keeping the valves from sticking every 500 hours. They may be doing something wrong, I don’t know. This seems less efficient than The Predator to me.

They had to have most of the helicopter rebuilt at 2,200 hours and it cost them close to $100,000.

At the risk of compounding the confusion I have a propeller that typically sees a little over 2,400 rpm at take off and 2,650 rpm at 95kts.

At 90 miles per hour at sea level I am typically burning a little over 7.5 gallons per hour, in other words around 100 horsepower. At 110 miles per hour at 7,500 feet MSL I am typically burning a little less than 9 gallons per hour AKA 120 horsepower.

As I recall you are supposed to keep from using all that horsepower in a Robinson 22 at sea level because the transmission is not up to it. My recollection is that at altitude you can use all the engine will give which at 7,500 feet is 120 horsepower.

As far as I can tell the Predator was not designed to be efficient and it succeeds at that.

I expect Mariah Gale to be at least 20% less inefficient; time will tell.

In the real world rather than the hyperbole of sales brochures every aircraft is different. I can fly places flanking a Robinson 22 and keep up just fine. We don’t compare gas receipts.

I have flown several Robinson 22s and they are not to my taste.

If I was to have a helicopter I would prefer the Robinson 44. I like everything about it better than a Robinson 22.

I would also like to have an IO-540 in Mariah Gale.

For the kind of flying we do being out in the open means a lot to us.

Taking the doors off a Robinson is a poor substitute for cavorting topless.

I took Carl, a 70 year old motorcycle friend flying today and he enjoyed the smell and temperature changes the same as I do.

I spent no time thinking about efficiency as we made a 50 mile flight into an 80 mile flight with a top speed of 100 miles per hour, a vertical descent at 0 air speed, climbing to 3,500 feet and descending to 500 feet at least four times for fog and terrain clearance. As I think about it now it was probably not the most efficient way to fly.

Suffice it to say in my opinion anything with a rotor is the antithesis of efficient and more or less inefficient has little solemnity for me.

For me personally if efficiency is measured in fun per dollar a gyroplane wins by a wide margin.

If the criterion is how efficiently money is turned into noise I feel a helicopter is the comfortable winner.

Thank you, Vance
 

Attachments

birdy

Newbie
Joined
Mar 19, 2004
Messages
7,052
Location
Alice Springs-central Oz.
Aircraft
open frame single seat & a 'wasa' RAF, among other types.
Total Flight Time
7000 odd, bout 5000 gyro
Wait a minute. We do have 75% for the Helo, from it's own flight manual.
Local 'average' DA also makes compareing numbers meaningless.
Tho the 2 machines iv compared are flyn in the same air, im sure 2 factories figures would lean towards the more faverable conditions.

In my experience published performance figures are often divergent from real world performance.
So its not just me then? ;)

I like the comparison which one can stay airborn the longest under 25 mph.....that would not be fair of course!
Thats rite Stan, your turbine would be burn'n alot more n me 912 at 25mph. ;)
 

StanFoster

Active Member
Joined
Nov 16, 2003
Messages
16,895
Location
Paxton, Il
Aircraft
Helicycle N360SF
Total Flight Time
1250
Birdy- You got me! I should have said less than 20 mph, or less than 15 mph. Ha Vance- We all basically work up to the type of flying that suits our interest best. Your type of flying is out in the open, mine is behind a windshield with the sides open. You love flying over the terrain doing very cool cross country flights. My love is flying in the terrain, having the capability to landing and taking off most anywhere. You enjoy going somewhere more than anyone I know, and I feel like no one loves going nowhere while hovering as much as I do. If I flew from airport to airport with no desire to turn the air around me into a runway at anytime, I wouldn't even consider a helicopter! But, you and I are flying how we like and that is what's important. So comparing the efficiency of both types of rotorcraft doesn't mean a thing, as long as our fun per hour is the most efficient it can get. Can you imagine everyone wanting to fly the same way? Keep stirring the air over the terrain with the wind in your face going somewhere, and I will keep stirring the air in the terrain going nowhere at all with no wind in my face! Stan
 

dcnblues

Newbie
Joined
Sep 2, 2012
Messages
35
Location
San Francisco
Total Flight Time
95
...comparing the efficiency of both types of rotorcraft doesn't mean a thing, as long as our fun per hour is the most efficient it can get. Can you imagine everyone wanting to fly the same way?
In a world full of people only some want to fly
Isn't that crazy?
-Seal
But if I have two locations 50 miles apart, with a little bit of room at each place (just enough for a gyro to take off), and I'm deciding on what kind of aircraft I want, and it will be a regular trip and future fuel costs are part of the budget, it will mean something.

I don't have that setup, but wish I did. In any case, they're damn close, which is what the original thread poster wanted to know.
 

Stan V

Active Member
Joined
Jan 23, 2011
Messages
1,271
Location
Monticello, GA
Aircraft
Piper Arrow/RAF2000
Total Flight Time
450
Until it's time to do the maintance, I'll take the gyro. PRA 41973
 
Top