Robinson R44
Join Date: Apr 2002
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I just got any email from a dealer for RHC that talks about the delay in releasing the Raven II.
" With regards to problems with the Raven II, the only area of concern lay with the fuel servo which is a component of the fuel injection system. Evidently during testing, RHC discovered some inconsistant problems with the smaller unit that Lycoming had installed & certifiied on their engine. These problems were solved by installing a larger servo. Even though RHC had obtained the type certificate for the Raven II, the engine's type certificate was obtained by Lycoming. Lycoming received certification from the FAA recently to install this larger servo and now deliveries of the Raven II are getting started. "
If anyone has heard anything else, please post.
nik.
" With regards to problems with the Raven II, the only area of concern lay with the fuel servo which is a component of the fuel injection system. Evidently during testing, RHC discovered some inconsistant problems with the smaller unit that Lycoming had installed & certifiied on their engine. These problems were solved by installing a larger servo. Even though RHC had obtained the type certificate for the Raven II, the engine's type certificate was obtained by Lycoming. Lycoming received certification from the FAA recently to install this larger servo and now deliveries of the Raven II are getting started. "
If anyone has heard anything else, please post.
nik.
PPRuNe Enigma
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t'aint:
I'm very pleased to report that I have not had the opportunity to check this out first-hand 
- but, yes this was in connection with the injector servo problems.
Where did you hear this? Have you been able to check it out? Is it true?
- but, yes this was in connection with the injector servo problems.
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RavenII Problem
I heard that the injection system was causing problems as it was setup for hot and high......so much closer to sea level it was coughing & spluttering...just a rumour though!
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Raven II
Hi there,
Here's some info I got from the RHC in relation to the new Raven II.
The FAA Type Certificate has been completed and received for the R44 II. After FAA certification was received our engineering department decided they were not completely happy with the fuel control servo and the part was replaced with another type servo. The new servo had to be certified hence the delay. Deliveries began last month and so far every one seems to be very happy with their R44 Raven II.
Regarding the Raven II striping scheme it is similar to the Raven but a tad different. Pictures and a flyer for the Raven II should be available to Robinson authorized dealers by the end of the year. Should you have a real keen interest, you might try contacting one or both of the Robinson authorized R44 dealers below, they have each already taken delivery of a new R44 Raven II helicopter.
Best regards,
Robinson Helicopter Company
Milly Donahue, Sales Manager
Quantum Helicopters, Inc.
Contact : Mr. Neil Jones
Chandler, Arizona
Tel: 480-814-8118
Hampton Roads Charter Service
Contact: Mr. David "Andy" Gibbs
Chesapeake, Virginia
Tel: 757-593-6111
Here's some info I got from the RHC in relation to the new Raven II.
The FAA Type Certificate has been completed and received for the R44 II. After FAA certification was received our engineering department decided they were not completely happy with the fuel control servo and the part was replaced with another type servo. The new servo had to be certified hence the delay. Deliveries began last month and so far every one seems to be very happy with their R44 Raven II.
Regarding the Raven II striping scheme it is similar to the Raven but a tad different. Pictures and a flyer for the Raven II should be available to Robinson authorized dealers by the end of the year. Should you have a real keen interest, you might try contacting one or both of the Robinson authorized R44 dealers below, they have each already taken delivery of a new R44 Raven II helicopter.
Best regards,
Robinson Helicopter Company
Milly Donahue, Sales Manager
Quantum Helicopters, Inc.
Contact : Mr. Neil Jones
Chandler, Arizona
Tel: 480-814-8118
Hampton Roads Charter Service
Contact: Mr. David "Andy" Gibbs
Chesapeake, Virginia
Tel: 757-593-6111
Last edited by James Roc; 3rd Dec 2002 at 00:10.
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Raven II
Got a chance to see the new Raven II after assembly but with the avionics not yet installed,black with gold trim (new styling) and it looks great! New inclusions are starter buttons on the cyclic and the collective so as to simplify mid flight engine restart in the eventuality of a cutout,also there is a new carbon monoxide detector light along with the other warning lights.The startup sequence is slightly different due to the new fuel injection system (only pushing the mixture full rich after starting) but should take about the same time as the Raven.The guys I spoke to said that it had a different sound in flight and was noticably quieter,fuel burn is about the same...hmmm,now where's my cheque book!!!
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Did they make any other modifications besides the electronic injection? Im a little confused as to how this would make it quieter.... anyone, anyone. Oh well I've got nowhere to be.
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I gather that the ends of the main rotor and the tail rotor blades have been rounded. This not only reduces the noise level of the blades but also affects the sound envelope it creates around the aircraft.
I've got no idea how it works as I'm not a sound boffin !
I've got no idea how it works as I'm not a sound boffin !
The strength of the vorticity that is trailed into the wake from a rotor blade is largely dependant of the lift distribution across the span of the blade. At the tip (and the root in some cases) there is a large discontinuity in the lift distribution therefore a strong vortex is trailed.
We have shown recently using Computational Fluid Dynamics techniques that even the addition of a cap that is a simple revolution of the aerofoil shape will significantly reduce the strength of the vortex that is created. This in turn means that the blade vortex interactions that occur in the wake, will also be less severe and so the noise produced by the aircraft will be reduced.
It's exciting stuff really!
As to the effect of fuel injection on the engine.....well i'm not an engine person really, but I would guess that by using electronic fuel injection the nature of the combustion process in the cyclinder and the reacting fluid dynamics are significantly altered. I would expect that less fuel is injected into the cylinder for a given power output than would be required for the carb'd version of the engine by virtue of the well known improvements in combustion effeciency obtained using a good fuel injection system. Therefore this implies that less energy is available to create noise, vibration etc etc. More specifically, I would expect the pressure pulse created as the burning gas mixture expands to be smoother with fuel injection by virtue of a better atomised fuel spray. This is due to a smoother propagation of the flame front and may therefore be expected to have a reduced excitation effect on the engine struictural dynamics. Again a signicant noise source.
Hope this helps......right, back to work.
CRAN
We have shown recently using Computational Fluid Dynamics techniques that even the addition of a cap that is a simple revolution of the aerofoil shape will significantly reduce the strength of the vortex that is created. This in turn means that the blade vortex interactions that occur in the wake, will also be less severe and so the noise produced by the aircraft will be reduced.
It's exciting stuff really!
As to the effect of fuel injection on the engine.....well i'm not an engine person really, but I would guess that by using electronic fuel injection the nature of the combustion process in the cyclinder and the reacting fluid dynamics are significantly altered. I would expect that less fuel is injected into the cylinder for a given power output than would be required for the carb'd version of the engine by virtue of the well known improvements in combustion effeciency obtained using a good fuel injection system. Therefore this implies that less energy is available to create noise, vibration etc etc. More specifically, I would expect the pressure pulse created as the burning gas mixture expands to be smoother with fuel injection by virtue of a better atomised fuel spray. This is due to a smoother propagation of the flame front and may therefore be expected to have a reduced excitation effect on the engine struictural dynamics. Again a signicant noise source.
Hope this helps......right, back to work.
CRAN
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Heli-Air's got one in - Q says he's flown it and it's got 'bags more power.'
It says here: 'The R44 Raven II features the new Lycoming IO-540 Fuel Injected, Angled-Valve, Tuned Induction engine, designed by Lycoming in co-operation with Robinson exclusively for the Raven II. The new engine is derated to 245hp for five minutes, and 205 hp max continuous rating. This allows a 100 lb increase in the R44's gross weight and increased IGE and OGE hover ceilings, while eliminating the carburetor and the need for carburetor heat.
'Both sets of rotors are fitted with noise attenuating blade caps that decrease flyover noise by 1db. The main rotor blades also have more surface area for increased lifting capability at altitude.'
I don't want to be a wet blanket but I suspect it's still going to be subject to induction icing in UK weather. You've still got atomisation of fuel, you've still got a butterfly. Only thing you haven't got now is carb heat.
It says here: 'The R44 Raven II features the new Lycoming IO-540 Fuel Injected, Angled-Valve, Tuned Induction engine, designed by Lycoming in co-operation with Robinson exclusively for the Raven II. The new engine is derated to 245hp for five minutes, and 205 hp max continuous rating. This allows a 100 lb increase in the R44's gross weight and increased IGE and OGE hover ceilings, while eliminating the carburetor and the need for carburetor heat.
'Both sets of rotors are fitted with noise attenuating blade caps that decrease flyover noise by 1db. The main rotor blades also have more surface area for increased lifting capability at altitude.'
I don't want to be a wet blanket but I suspect it's still going to be subject to induction icing in UK weather. You've still got atomisation of fuel, you've still got a butterfly. Only thing you haven't got now is carb heat.
Iconoclast
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Besides that, consider this,
To: CRAN
In a conventionally aspirated engine (with a carburetor) the fuel air mixture passes into the induction system. This mixture must change flow direction in order to pass through the headers leading to the individual cylinders. During this change in direction you get a condition called “Centrifugal slinging” which causes some of the fuel to separate from the airflow. This separated fuel will end up in the cylinder(s) closest to the carburetor and the difference in fuel air charge will cause the closest cylinder(s) to run rich and the furthest cylinders will run lean. This difference will cause a difference in the exhaust note for the various cylinders and possibly result in a harmonic amplification of the noise emitted by the exhaust.
Fuel injection solves this problem by injecting the same amount of fuel directly at the intake valve.
As far as icing is concerned it should not happen even though there is a butterfly valve. Icing is caused by the expansion of the fuel air mixture as it comes out of the jet and passes through the carburetor. Any time you have expansion you have cooling which cools the carburetor body. Flying through moisture laden air at a specified temperature assists in this cooling and the moisture accretes out on the carburetor body, building up to the point of causing engine stoppage.
This should not happen on an injected engine.
Many moons ago the Holly Carburetor company designed a carburetor that would not Ice-up. The US Navy had some problems on the carbs. on R-2800 engines. They installed this carburetor on many R-2800s used on PBMs. They lost several PBM due to engine failure (both engines at the same time) because the Holly anti icing carburetor generated ice faster than an ice machine in a restaurant.
In a conventionally aspirated engine (with a carburetor) the fuel air mixture passes into the induction system. This mixture must change flow direction in order to pass through the headers leading to the individual cylinders. During this change in direction you get a condition called “Centrifugal slinging” which causes some of the fuel to separate from the airflow. This separated fuel will end up in the cylinder(s) closest to the carburetor and the difference in fuel air charge will cause the closest cylinder(s) to run rich and the furthest cylinders will run lean. This difference will cause a difference in the exhaust note for the various cylinders and possibly result in a harmonic amplification of the noise emitted by the exhaust.
Fuel injection solves this problem by injecting the same amount of fuel directly at the intake valve.
As far as icing is concerned it should not happen even though there is a butterfly valve. Icing is caused by the expansion of the fuel air mixture as it comes out of the jet and passes through the carburetor. Any time you have expansion you have cooling which cools the carburetor body. Flying through moisture laden air at a specified temperature assists in this cooling and the moisture accretes out on the carburetor body, building up to the point of causing engine stoppage.
This should not happen on an injected engine.
Many moons ago the Holly Carburetor company designed a carburetor that would not Ice-up. The US Navy had some problems on the carbs. on R-2800 engines. They installed this carburetor on many R-2800s used on PBMs. They lost several PBM due to engine failure (both engines at the same time) because the Holly anti icing carburetor generated ice faster than an ice machine in a restaurant.
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Oooo... another 44 to avoid at HeliAir. If they get any more I'll have nowhere to park next time I take CD for a spin.
Still, if Q's in a good mood maybe he'll show this humble 22 driver around the new toy
Anyone taking bets how long before some form of inlet heating arrives??
Still, if Q's in a good mood maybe he'll show this humble 22 driver around the new toy
Anyone taking bets how long before some form of inlet heating arrives??
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Fuel Injection Icing
I don't know if it is for icing reasons, but every modern fuel injected car I have ever seen has coolant passages to warm the intake manifold.
Hans
Hans
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The experience of injected helicopter lycomings is already out here as Enstrom use them. Cutting out during autos is not just a Robinson problem. From my 1998 Enstrom POH " Sudden power cuts to idle are not recommended since the fuel injector is sensitive to improper adjustment of idle mixture, idle RPM and sudden momentary leaning of mixture caused by sudden power reduction". "Autorotation practice should be carried out over suitable terrain". At least it makes you get good at them!
Is Robinson's injection the same mechanical Bendix system used on the Enstrom? The start procedure is the same.
Induction icing is not an issue.
Why do Robinson need a 540 for 205 BHP?
My normally aspirated Lycoming 360 produces 205BHP and only uses 11 Gallons per hour. How much does the R44 use?
The Enstrom Turbocharged 360 can produce 225BHP continuously.
Will Robinson allow leaning the mixture in flight as Enstrom do?
Is Robinson's injection the same mechanical Bendix system used on the Enstrom? The start procedure is the same.
Induction icing is not an issue.
Why do Robinson need a 540 for 205 BHP?
My normally aspirated Lycoming 360 produces 205BHP and only uses 11 Gallons per hour. How much does the R44 use?
The Enstrom Turbocharged 360 can produce 225BHP continuously.
Will Robinson allow leaning the mixture in flight as Enstrom do?
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T'aint
I am aware Robinson derates its engines in both 22 & 44. the question is why?? Is Robinsons cooling fan inadequate? Will the airframe or power train not take it? When Frank did the design, was it the only engine he had in stock?! It seems slightly pointless to use a big expensive engine and strangle it when a smaller one could do the same job and use less fuel and be cheaper to overhaul.
And while we are on the subject of limits, how come Enstrom can turn an O360 at 3050 RPM without it falling apart? If you did that to a Beta 2 engine for 10 seconds you would be facing a large bill for an overspeed. Ask Nr Fairy.
Now there's a thought, An Enstrom HIO360C1A engine in a R22, Should be a pretty easy conversion. It should more or less bolt straight in. Fuel injection, no carb heat, 205BHP. Loads of power. Could be a Beta 2/2. How about it Frank.
I have a spare Enstrom engine if anyone wants to try it.
I am aware Robinson derates its engines in both 22 & 44. the question is why?? Is Robinsons cooling fan inadequate? Will the airframe or power train not take it? When Frank did the design, was it the only engine he had in stock?! It seems slightly pointless to use a big expensive engine and strangle it when a smaller one could do the same job and use less fuel and be cheaper to overhaul.
And while we are on the subject of limits, how come Enstrom can turn an O360 at 3050 RPM without it falling apart? If you did that to a Beta 2 engine for 10 seconds you would be facing a large bill for an overspeed. Ask Nr Fairy.
Now there's a thought, An Enstrom HIO360C1A engine in a R22, Should be a pretty easy conversion. It should more or less bolt straight in. Fuel injection, no carb heat, 205BHP. Loads of power. Could be a Beta 2/2. How about it Frank.
I have a spare Enstrom engine if anyone wants to try it.
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In australian mustering operations i have rarely seen a Hughes 300 engine (O360) or a Bell 47 engine (VO435) which scream their little hearts out at 3200rpm get through their full lives without some sort of major work while R22's which run at 2700rpm go to full life year after year. Frank's derating works fine.
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Gaseous
I don't know how long you've had your Enstrom or what your bills look like, but I do know why some engineering companies won't have Enstroms in the hangar - because they're tired of explaining the bills to customers.
The Robinsons are derated to reduce engine wear, increase life and reduce maintenance bills.
As a side-effect, the derating improves safety because when a Robinson is operating at nominal maximum power it still has two or three inches of MAP and 30hp in the locker, which will get you out of trouble if you're prepared to scream the engine up to the level that Enstroms operate at all the time.
PS: Don't be in a hurry to give that spare engine away. You're gonna need it.
I don't know how long you've had your Enstrom or what your bills look like, but I do know why some engineering companies won't have Enstroms in the hangar - because they're tired of explaining the bills to customers.
The Robinsons are derated to reduce engine wear, increase life and reduce maintenance bills.
As a side-effect, the derating improves safety because when a Robinson is operating at nominal maximum power it still has two or three inches of MAP and 30hp in the locker, which will get you out of trouble if you're prepared to scream the engine up to the level that Enstroms operate at all the time.
PS: Don't be in a hurry to give that spare engine away. You're gonna need it.