Flying Cavalon at Altitude

[rcflier]

I think prop setting is to be inquired about in how it has been set to perform. I do not really know why people are going for these expensive complex props because with the power of 915 or 916 you are set it to get decent compromise all the way from the ground to at least 10000 feet. The only thing it gives is 7 to 9 mph extra cruise speed in a gyroplane and if you are worried about that, you should have been in an airplane to begin with.

I often read a 914 (and then also other turbo engines) should perform best with a constant speed prop.
And those who use an in-flight adjustable Ivoprop have a better mileage than I have with my fixed prop.
But anyway, that's what I could afford. I recently discovered, I could run it a bit more coarse.
No need to go to full 588 rpm when taking off. I am now at 5600 WOT and I *think* I use a bit less fuel.

 

[cbb61032002]

The fixed wing standard for such things is black for throttle, blue for prop, and red for mixture. It would be sensible design to follow that scheme and make the prop knob blue.

Hey WaspAir,

Appreciate you trying to problem solve for me but it is not an adjustable (in cockpit) prop. Its an MT 34 (hydraulically controlled) prop. I talked to the guys at Cierva who built it and we may be able to change some of the programming but it is not something I can adjust

 

[cbb61032002]

Sounds like a prop control issue to me.

I'm beginning to wonder!

 

[cbb61032002]

What was your manifold pressure and prop RPM? It will tell us what the problem is. I hope there is a MAP indicator as well as a prop RPM gauge and engine RPM gauge, this would be standard on any certified aircraft with constant speed prop. I suspect you don't have them and rely on some settings that are preset, but maybe I'm wrong.

I will check manifold pressure next time I fly. I don't think there are separate RPM gauges. I will check with previous owner. I also suspect I am relying on presets.

 

[cbb61032002]

Hi - As stated there can be a number of reasons for your issue but I would also encourage you to look at the weight side of things.

17 US Gals = c. 46kgs
Your aircraft empty weight is unlikely to be significantly different than the one in my film about the aircraft 4 years ago - c. 340kgs.
Couple of back packs? = 10kgs?
So we are at almost 400kgs already and the maximum take off weight of these aircraft is 560kgs.

You and wife you say are 155 and 190 = 345lbs or 156kg.

You are on the absolute limit weight wise for the aircraft.....and that depends on the fudge factor for fuel exact number, weight of bag and other tat in the cabin, empty weight of aircraft and how heavy your own clothes, headsets, map bag, etc are. At some point it all makes a difference.

Hmm, this is interesting! How would anyone fly one of these above 5000 feet? Only fly with one person? My wife and I are well under the person seat limits of 242 lbs.

 

[cbb61032002]

No I'm not saying that but I also think the numbers start to become flakey [just speaking openly]. Suddenly we find we are right on the max weight even with some conservative assumptions and so how was the prop set? what speed was actually being flown? How long had it been climbing for, take off power is available for 5mins remember - just as a for example. No idea. Maybe it was accurate but likely as not it wasn't.

No reason for me to fudge numbers. We could have been over the weight limit and if so I want to learn from the mistake and what to do next time! But the numbers should be pretty accurate (unless my wife is lying to me about her weight ha!). To be clear we were able to fly up to 6000 ft with max power but were just not able to maintain it with 5500 engine rpms or below.

If the weight stuff is the issue and not the prop then I don't see how Cavalon could fly above 4 or 5k with two people unless they were very light! I thought my wife and I being under the 242 lb person weight limit would give us plenty or wiggle room weight wise! Appreciate your math showing weight number!

 

[WaspAir]

Hey WaspAir,

Appreciate you trying to problem solve for me but it is not an adjustable (in cockpit) prop. Its an MT 34 (hydraulically controlled) prop. I talked to the guys at Cierva who built it and we may be able to change some of the programming but it is not something I can adjust

The manual I quoted above is for the MT-34.

As I understand it, it can be operated fixed pitch if you choose to restrict it at installation, but there is of course no hydraulic control at all for that mode. If operated constant speed, there must be a way to choose the speed at which it is governed, in flight. If there is any hydraulic governing going on, it doesn't meet the LSA rules that require fixed pitch or ground adjustable prop. The pitch will be changing all the time to hold constant speed.

I have never seen a governed prop that did not have a pilot control, even if only to select among presets such as climb or cruise.

Perhaps what you have is a potentially constant speed prop (a possibility for that model) that is not operating in that mode as installed.

P.S. You should not need separate prop and engine rpm guages, as there is a fixed crankshaft to prop gearing ratio, and only one is needed to monitor rpm. A manifold pressure guage is necessary to determine power setting when prop rpm is governed to a predetermined value. If you have no manifold pressure guage, you are likely operating fixed pitch.

 

[PJB]

No reason for me to fudge numbers. We could have been over the weight limit and if so I want to learn from the mistake and what to do next time! But the numbers should be pretty accurate (unless my wife is lying to me about her weight ha!). To be clear we were able to fly up to 6000 ft with max power but were just not able to maintain it with 5500 engine rpms or below.

If the weight stuff is the issue and not the prop then I don't see how Cavalon could fly above 4 or 5k with two people unless they were very light! I thought my wife and I being under the 242 lb person weight limit would give us plenty or wiggle room weight wise! Appreciate your math showing weight number!

yep I hear you and I’m just saying that with the quick and rough math it does seem at the limit (and right on the bubble) As you and others point out that likely isn’t the full picture and maybe the prop is faulty either in operation by technical means or otherwise. But maybe a night in with the POH and a trip with your instructor would be the best thing because the old saying - a superior pilot uses his superior judgement to avoid using superior skill… be lucky.

 

[WaspAir]

And that instructor should be one who can legally fly with a governed prop, if that is really what you have. That eliminates many Sport Pilot / Sport CFIs.

 

[cbb61032002]

yep I hear you and I’m just saying that with the quick and rough math it does seem at the limit (and right on the bubble) As you and others point out that likely isn’t the full picture and maybe the prop is faulty either in operation by technical means or otherwise. But maybe a night in with the POH and a trip with your instructor would be the best thing because the old saying - a superior pilot uses his superior judgement to avoid using superior skill… be lucky.

Did some math with POH and Weight and Balance. Apparently we have a particularly heavy Cavalon and have a small useful weight load (luckily my wife and I aren't too heavy!). Will need to be very careful with weight while flying in the future! Thanks for the help guys!

 

[Abid]

I often read a 914 (and then also other turbo engines) should perform best with a constant speed prop.
And those who use an in-flight adjustable Ivoprop have a better mileage than I have with my fixed prop.
But anyway, that's what I could afford. I recently discovered, I could run it a bit more coarse.
No need to go to full 588 rpm when taking off. I am now at 5600 WOT and I *think* I use a bit less fuel.

Sone if these props are $10k. You can burn a ton of fuel for that. And yes you get about 7 to 9 mph extra cruise at top end. You should let it go to 5800 RPM for takeoff run and then to climb 5600 RPM after initial 500 feet. That’s what the whole point is. Ivo us the cheapest I. Flight adjustable prop. It euros though there isn’t a nice indication for its pitch setting. You just have to look at the RPM. Otherwise it works just as well as a $10k one while spending $3500.
The only issue with it is the brushes burn out unless you replace their provided 10 amp CB with a standard aviation 5 amp CB. Then brushes stop burning out so quickly.

 

[Abid]

Did some math with POH and Weight and Balance. Apparently we have a particularly heavy Cavalon and have a small useful weight load (luckily my wife and I aren't too heavy!). Will need to be very careful with weight while flying in the future! Thanks for the help guys!

Haha. That’s a trend for aircraft from Germany. They say one weight but when you actually look at your aircraft and weigh it and do the W&B it’s like an extra 10%. Must be a German thing. I ran into the sane issue in an airplane the other day.

 

[Aerofoam]

Haha. That’s a trend for aircraft from Germany. They say one weight but when you actually look at your aircraft and weigh it and do the W&B it’s like an extra 10%. Must be a German thing. I ran into the sane issue in an airplane the other day.

I think their women use the same formula.....
Just saying....

 

[Abid]

I think their women use the same formula.....
Just saying....

Oh no. Give some warning before making such chilling remarks. I got coke right into my lungs and all over a shirt.

 

[Aerofoam]

Oh no. Give some warning before making such chilling remarks. I got coke right into my lungs and all over a shirt.

Yeah, when I see some of the "Zingers" I have actually spit coffee on my laptop....

 

[bell206]

Where is that 2000 ft a minute climbing Cavalon 915 they claim on youtube? As Ricky would say they've got some splane ing to do Lucy.

 

[PJB]

Light fuel load and one up you will probably get close to 2K/min with a 915. If you are overweight then who knows. AutoGyro just need to relax on the sales pitch and do a better customer hand over.

 

[Abid]

Light fuel load and one up you will probably get close to 2K/min with a 915. If you are overweight then who knows. AutoGyro just need to relax on the sales pitch and do a better customer hand over.

I can’t even get 1500 FPM sustained climb rate in an AR-1 which is tandem seating. I get around 1430 FPM. There is no way a fat wide Cavalon is climbing better than an AR-1. Physics is a bitch.
Climb rate in aviation is ALWAYS at gross weight at sea level in ISA. Unless very specifically stated otherwise. It seems like a lot of marketing is done using non standard aviation practices. That can be misleading. People need to do their due diligence to compare apples to apples.

 

[Mayfield]

I can’t even get 1500 FPM sustained climb rate in an AR-1 which is tandem seating. I get around 1430 FPM. There is no way a fat wide Cavalon is climbing better than an AR-1. Physics is a bitch.
Climb rate in aviation is ALWAYS at gross weight at sea level in ISA. Unless very specifically stated otherwise. It seems like a lot of marketing is done using non standard aviation practices. That can be misleading. People need to do their due diligence to compare apples to apples.

Abid

You have an insightful way of explaining.

It seems many manufacturers lie by omission. Without a standard datum, performance claims are at best suspect.

Jim

 

[Rick E]

This photo is climbing through 7500’to 8500’at 5200rpm in a 914 Cavalon with an IVO prop. It was a slow climb but wasn’t that difficult.