Lets make a helicopter

[bugdevheli]

There was an item on rotorheads a day or so ago suggesting pruners got together and designed or built a helicopter. It would be interesting to hear answers to the following. What engine size.? What make of engine.? What max weight.? Number of seats reqrd.? Total maximum cost.allowable.? Ammount of inertia required (give it in seconds a la Robinson) Number of blades.? Any other requirement in order to better the R22.

[Dave_Jackson]

bugdevheli,

As an initial step, what about developing an acceptable list of the desired uses for this helicopter?

Here is a list that was developed from a previous request on PPRuNe. The web page relates to a specific craft but it may provide suggestions for this project; Uses for UniCopter (http://www.synchrolite.com/B354.html )

[rotorboater]

1, Run on jeta1 (Diesel engine)
2, 2 comfortable sized seat
3, High enertia rotor
4, 2 blades or folding blades for small hangar
5, enough bagage for golf clubs or similar
6, no calander timed life parts
7, affordable enough to buy

Oh and how about a net to catch all those flying pigs that will be up there 1st!;)

[Hilico]

I was going to ask for tandem seating (a la AH64) simply for the superb view (to identify hazards / other aircraft) but I suppose that would probably play havoc with the CoG in a light machine.

Solo from front? Yes, unless pilot weight > 70kg and fuel less than 65% or maximum gust forecast greater than 35% of mean wind speed and Skywatch installed...

[Flingwing207]

Supercharged 2-stroke diesel (Jet-A) - possibly a Dyna-Cam? (http://www.dynacam.com/index.htm)
rigid 4-bladed rotor system w/folding option
fenestron anti-torque
detatchable belly-mounted cargo pod
skid gear
two seats plus small cargo area behind seats
900-lb useful load
250nm range with 20-min reserve
100-kt cruise speed
$300,000 USD fully equipped as an IFR trainer...I'll get right on it!

[CRAN]

It was me that made the original suggestion on the BCAR regulations thread regarding building our own machine. In response to bugdevheli's initial questions about the nature of the machine, one must first decide if it is to be a kit or is it to be a entry-level commercial helicopter, such as the R22. It is important to get this straight because the requirements and potential markets for the two machines are very different as are the technology strategies that you would employ.

Let’s assume we are talking kits...as was my initial intention...

The priorities for such a machine are very simple:

(1) RELIABILITY & SAFETY
----------------------------
The machine should be mechanically reliable and DESIGNED to the same standards as are required for fully certified light helicopter. The aircraft should be designed with low-time, inexperienced, low-ability pilots in mind. The handling qualities should be optimised to be docile, benign and to give the pilot the maximum time to react to any given situation either power on or off. The key points here are:

(a) High Inertia Rotor System (4 seconds pilot delay in cruise)
(b) De-rated, fuel-injected aircraft quality engine
(c) Adequate power (P/W = 0.23 hp/kg)
(b) Docile controls
(c) Benign reaction to low-g flight - careful optimisation of tail rotor thrust line.

(2) CRASHWORTHY AIRFRAME
---------------------------------
It doesn't matter what is done in terms of making the aircraft easy to fly and benign, entry-level helicopters will be crashed and will be crashed frequently, due to pilot error. Therefore, any engineer designing a new machine for this end of the market needs to accept 'mammoth crashworthiness' as a requirement for the machine. Crashworthiness means two things, the occupant volume must remain intact with the occupants safely secured within it and the surrounding airframe must be designed to absorb as much energy as possible. In addition, the fuel tanks must be rupture resistant to limit the well known fire risk.

(3) LOW, LOW COST
----------------------
The machine must be a minimum cost machine, though not at the expense of safety. Hourly cost accounting is somewhat different for kit helicopters as they rarely if ever fly enough hours to reach overhaul since they are entirely private machines, so much of the savings can be obtained here. Based on UK prices the hourly operating cost for a kit helicopter should be £45-£50/hour. [NOTE: Fuel is very expensive in the UK and accounts for about £30/hr] The target kit-price for the machine should be £45-50K, including engine and basic instruments and excluding taxes.

(4) SIMPLE LOW MAINTAINANCE REQUIREMENTS
----------------------------------------------------
One key design requirement is that the machine must require very little maintenance and what it does require must be easy to achieve. The machine must be designed with easy access to key components in mind and simple maintenance procedures. The machine should employ a 4000hr global retirement schedule, with no calendar time limit, rather components should be on-condition if they are not fight-time expired. Engine would be exchanged at 2000hrs as per manufacturers requirements.

(5) PERFORMANCE
--------------------
The aircraft should be designed to provide 'acceptable' performance. By this I mean, approx. 100kt cruise and 120kt max level flight speed. Range of 300nm @ 100kt, and the ability to achieve this while carrying two 16st [224lb] passengers and three hours of fuel, with acceptable power margins. Performance at altitude to be no worse than the existing R22 Beta II, though my inclination would be to improve it somewhat perhaps offering the turbo-normalised engine as an option.

(6) APPEARANCE & FIXTURES
--------------------------------
The aircraft should be drop-dead gorgeous, have doors that fit and have conventional dual controls. The interior should look like that of a modern car rather than a sit-on lawn mower.


ADDITIONAL INFORMATION
-----------------------------
The aircraft would be powered by a Superior Air Parts XP-IO-360 engine (or XP-TNIO-360 for high altitude operators), de-rated in speed and power to 160hp (5 mins) and 140 hp continuously. 100% of the parts are FAA certified (though it’s not a certified engine) and Superior has spent the last 30 years tweaking Lycomings design to improve both performance and reliability. The fuel injection eliminates carb icing and the engine can also be run on unleaded automotive fuel with no loss of performance. While I see the attraction of a diesel, no suitable engines exist for a 2-seat helicopter of this type, so we will stick with our bullet-proof big-bore flat fours!

An electronic rotor-speed govenor would be standard equipment.

The fuselage would be a hybrid construction, with a crashworthy composite cabin, steel-tube mid section and either aluminium or composite tail section.

The Rotor System would be a conventional high-inertia, two-blade teetering system, with either sealed rolling element feathering bearings or elastomeric feathering bearings ~ either way, low maintenance. Particular care would be paid to the aerodynamic design of the rotor system using the latest generation of rotor aerofoils, (multiple profiles across the span) for best possible performance. Blades would be composite construction.

The tail rotor would be a conventional 2-bladed open tail rotor, though it too would benefit from modern aerofoils and bearings.

There would also be a large internal volume for baggage (within the prescribed weight limits) and the option of cargo pods.

The cabin configuration is an interesting question. Initially my layouts had been for a side-by-side configuration as it is better for training and communicating with passengers. However a tandem arrangement as in the Apache is an all round better configuration from a technical standpoint. Contrary to Hilco's thoughts the tandem configuration will IMPROVE the CG over a sided-by side layout if designed correctly. In addition it provides major aerodynamic benefits that will lead to a higher cruise speed, not to mention the improved field of view for both parties and bigger feel to the cockpit.

If I had my way it would be a tandem seating arrangement, but i'm not sure that is what the market wants.

I hope this gives our group more of an understanding of what I have in mind and what is possible today!

CRAN
:)

[Vfrpilotpb]

Cran,

I do like the Tandam possibility, perhaps some sort of market reserch on this Rotorheads forum may show whether it would be acceptable by other pilots!

PeterR-B;)

[helimatt]

Check this out

http://www.lafhelicopters.com/english/index_en.htm

A shame that they have run out of money for the moment

[CRAN]

They are also using an automotive engine which is a BIG NO NO for reasons that will become very clear very quickly!

CRAN

[Head Turner]

The Lafhelicopters tandem design is so different to all other design concepts that to now fail due to funds is a loss to the rotorwing business.
Sure there will be many modifications to the design before it becomes commercial.
Sadly I do not have the required funds but somewhere there ought to be.
Here in the UK we sadly lack any enthusiasm for risk BUT have the Lafhelicopter team tried here in UK.
Such an idea should be persued to prove or otherwise the feasability of such a design to provide safe, easy to fly and relatively cost effective rotory flight. And yes get rid of the automotive engine and go for a single diesel or cosider a twin engine concept.

[Bomber ARIS]

"I want that one"

http://www.lafhelicopters.com/pictures/welcome/2004july.jpg

[RDRickster]

Many of the fixed-wing kits (especially amphibians) are being produced with the intention of becoming certificated aircraft in the future. Cost, time, cost, regulations, cost and other factors (such as money - in case I haven't mentioned it) make it prohibitive to begin with certification as the initial goal. The R22 made it in before the new certification standards went into effect.

To be realistic, consider starting with a kit... but have the fore-site to plan for future certification (this WILL affect the business process and design). Oh, and who is going to manage the shares of private stock for investment? Flying Lawyer, care to opine on the legal apects if based in the U.K? ;)

[CRAN]

RD,

As I suggested in my initial post, the reason why we have such a great opportunity at the moment is that there is a raft of new regulations that for once have made things a little easier on the start-up manufacturer.

You are absolutely correct that the machine must be designed to meet the fully certified regulations as I stated above, but initially not manufactured by an 'approved' organisation or tested to the same extremes. In the UK for example (and the rest of the EASA/JAR member countries) this would be done using the BCAR VLH (or similar) kit regulations initially, though the machine would meet EASA-VLR ~ which offers a fully public transport CoA for rotorcraft under 750kg but makes use of the unique simplicity of small helicopters to reduce the certification burden. I have figures direct from the CAA on how much this is likely to cost and it's not unrealistic.

In the US, which lets face it has the biggest kit market, the aircraft are essentially unregulated in the experimental sector so the aircraft could steam straight in there and they are moving to develop the Primary Category Rotorcraft regulations which are based on EASA-VLR for simple and light weight certificated machines…again good news.

With this in mind any design for a potential light rotorcraft must be a sensible configuration and designed in such a way at to provide an easy (or as easy as it can be) ride through these various regulations as it progresses from ‘Superkit’ to ‘Certified’ status over a number of years. My proposal does this.

CRAN

[Dave_Jackson]

What do you set as the craft's GW?

Regulations;
European ~ JAR Very Light Rotorcraft ~ Maximum weight 600 kg.
British ~ Very Light Helicopter ~ Maximum weight 750 kg
US ~ FAA - Light Sport Aircraft (potential for helicopter) ~ Maximum weight 560 kg
US ~ FAA - Ultralight (no pilot's license req'd) ~ Maximum Weight 115 kg, 143 kg w/ ballistic floats

[CRAN]

Dave,

EASA-VLR will be changed to 750kg as soon as the CAA get time to do it. Therefore, I would set the GW at around 700kg.

CRAN

[Dave_Jackson]

May I suggest a 3-blade constant velocity rotor with hub spring?

This head is currently being developed for the US Ultralight category. Full information on this project can be seen here. (http://www.synchrolite.com/S_Hub_CVJ.html) The intent is to start producing the components for the hub in three or four weeks.

Should the initial testing of the prototype show it to have the desired advantages and no disadvantages, the PPRuNe group could develop a second larger one (presumably for one main rotor :oh: ) . The development and testing of the two different sizes (250 / 2rotors = 125 kg) and (700 kg) should be mutual advantageous.

[Graviman]

Just thinking about your post Cran,

"RELIABILITY & SAFETY"

Yup.

"CRASHWORTHY AIRFRAME"

Yup.

"LOW, LOW COST"

Yup - absolutely!

"SIMPLE LOW MAINTAINANCE REQUIREMENTS"

Yup.

"PERFORMANCE"

Not so critical, since just getting up there is good enough for me.

"APPEARANCE & FIXTURES"

Well...

"ADDITIONAL INFORMATION"

Engine makes sense, but is not light or cheap.

"The fuselage would be a hybrid construction, with a crashworthy composite cabin, steel-tube mid section and either aluminium or composite tail section."

Hmmm, cost is starting to mount. Whats wrong with steel tube? And yes you gan get it to absorb energy in a crash...

"The Rotor System would be a conventional high-inertia, two-blade teetering system"

Yuk! Gotta be 3-blade rigid, cos chaps like me can't afford all the hours required getting aquanted with the dynamics of teetering rotors. If there is already electronics for RRPM control, why not go "trim by wire" to give rigid rotors nice characteristics in forwards flight? I'm actually a great fan of the original Lockheed spring/gyro control system.

"The tail rotor would be a conventional 2-bladed open tail rotor, though it too would benefit from modern aerofoils and bearings."

I've never been sure about tail rotors, they seem to have all sorts of interesting dynamics of their own. If the design is advanced aerodynamics, why not investigate stator downwash correction for anti-torque. Better still make the thing symmetrical, so idiots like me don't get left and right confused...

"The cabin configuration is an interesting question."

Oh thats easy, just me and the bloke behind me that utters those famous words: "Er - I have control!" :ugh:

Mart

[CRAN]

Mart,

Thanks for the constructive post. A few follow-up posts if I may:

ENGINE:
---------
As you have clearly picked up, the XP-IO-360 is the best compromise, out of a pretty dire set of alternatives. Not cheap and not light...tell me about it. Unfortunately, I am yet to discover a better solution. In the past I have studied a number of potential powerplant options and have consistently failed to satisfy all of my criteria. People often suggest using modern automotive engines, with their high level of technology and apparent reliability. Unfortunately to get a power-to-weight ratio out of a modern automotive engine that can come anywhere near a Lycoming you would have to run them so hard that I have grave reservations about their reliability and life expectancy. Indeed this is my major reservation about the Lafamme project referenced earlier in this thread. The interested readers can have a look at what the maximum continous power ratings are for some of ford’s automotive engines in INDUSTRIAL applications: www.fordpowerproducts.com

Another option is the use of a surplus APU or de-rated surplus turbo-shaft engines. Nonsense, not even going to discuss that!

Modern 2-stroke Engines; light, cheap...but unreliable.

Motorcycle engines? Again you would need to thrash them, so reliability and longevity is a problem.

Modern aero-diesels? None of an appropriate size, generally heavier, very expensive to buy and unproven reliability.

How about a VW-derivative as used by drag/street racers and fixed wing guys? Possible and definitely cheap, but I have serious reservations about the reliability. Have a look at: www.altimizer.com and www.scatenterprises.com/vwcatalog.html

How about a radial engine made out of VW-parts? Again proving the reliability is the issue.

How about a design from scratch, using as much automotive hardware as possible? This is definitely a good idea, but the time and cost of such an undertaking renders it economically unachievable for a kit helicopter project.

The bottom line about engines for helicopters is this...Helicopters are one of the most demanding duty-cycles conceivable for engines of any description. In addition, helicopters require an engine that is super-light and super-reliable and those two properties do not go hand-in-hand. Therefore, in any helicopter project the choice of the engine is by far the most important one and reliability must be the key driver of the selection.

I have selected the XP-IO-360 because it is a known quantity, installed properly, i.e. de-rated, it will provide reliable trouble-free power and inspire confidence in the pilots. We are able to make cost savings elsewhere in the aircraft (simple conventional design) and my proposal trades off these savings against using a good engine, rather than reducing the purchase price further still by using a lesser engine.

Remember, there is no free lunch and you certainly get what you pay for.

So I say again, for a KIT helicopter the only practical choice is the XP-IO-360. However, if I were designing a replacement R22, then I would definitely start with the development of a better engine...but what type, well, that would be telling.


FUSELAGE CONSTRUCTION:
------------------------------
What's wrong with steel tube? W E I G H T ! ! ! By the time you have a crashworthy, robust aircraft with sufficient fatigue strength and have faired it in nice fibre-glass clothing you have got yourself a hefty lump to lift. Remember, helicopters (especially ones that have to carry around heavy piston engines) are extremely sensitive to airframe weight. Unlike fixed wing aircraft every kilogram of extra weight you weld into the airframe, is a kilo of payload lost. The composites I had in mind for the cabin do not involve wall-to-wall exquisite space-age materials, as you rightly point out this would cost far too much, rather the careful application of fibreglass, with carbon and/or kevlar only where necessary. Not nearly as expensive as you might think! Infact it’s rather cost-effective in the volumes we’re talking about.

ROTOR SYSTEM(S):
---------------------
When you said rigid, did you really mean rigid or articulated or really rigid like the BO-105? There is a very strong case to be made for using a 3-bladed articulated hub but in my mind it is not the way to go.

You put three blades on and what do you get? More control power, more damping and hence better handling qualities and improved handling in low-g flight. Nobody would argue with this... But what about the substantial additional cost, weight and complexity. What about ground resonance? What about the additional dampers required in the undercarriage? What about the additional space required to hanger the beast or the cost and complexity of a blade fold mechanism? None of these items are really in line with our goal of designing a cheap and reliable helicopter are they?
I'm also not sure I agree with your sweeping generalisation regarding teetering machines. Have you flown a Bell 47 or a Hiller? Jet Ranger? The 'skittish' behaviour of the R22 is due to a variety of factors regarding its design and configuration and not because it uses a teetering rotor system. I don't believe that you would need 'all the hours to get acquainted with a teetering system' and even if you did ~ it would still be about a third the price of the same time in an R22, nearer a quarter in a S300!

With a project like this the most important thing is to take on something that is achievable with the resources available and it is for the reason that I discounted 'novel' configurations. By using a reliable engine and a simple 2-bladed teetering main and tail rotor we have an engineering task that is viable with limited resources. While I would certainly consider sculpting the tail boom to off-load the tail rotor in a passive manner in the hover two major issues spring to mind:

(1) The main rotor will be lightly loaded and so the downwash will be much slower than that of the MD900 for example (less than 40% in fact), therefore the area and indeed weight of such devices would present a significant design problem.

(2) With a passive device to 'assist' the tail rotor, invariably what would happen would be what was a helpful effect in one flight regime would be harmful in another, the net result being nothing special.


SEATING CONFIGURATION:
-----------------------------
:ok: I'm glad you like the tandem concept as there are some serious technical benefits for a two seater in this configuration!



GENERAL REMARKS:
----------------------
If a project such as this is to succeed then the technical task must be realistic and the resulting machine must meet the agreed specification. Mart and Dave have both highlight elements of the proposal that could be 'sexed-up' with novel, high-tech or more sophisticated systems that potential offer big advantages. Sadly, the reality of a project like this is that if it were ever to get of the ground it would receive the minimum funding imaginable and those that had invested hard-earned pennies would want results...and quickly. The configuration I have laid out for our machine is simple and achievable. All of the technologies employed have been done-to-death either in the aircraft sector or other sectors and only need to be 'embodied' in the aircraft. If there were technical problems along the way, there is plenty of experience in our group and the wider community that would be able to shed some light on it and get us moving again quickly.

As Nick said in his Pilot Magazine interview; 'This is Dan's all you can eat restaurant and that's all you can eat!' Keep it simple and to an agreed specification and we can succeed, over complicate it and we will certainly fail. I spent many years doing 'blue-skies' research and applied research in the helicopter industry (aerodynamics) and i'll tell you now, novelty will get us nowhere fast.

IMHO if it was going to be done then the design should be an exceptionally-crafted embodiment of proven and reliable technologies that will serve us all safely, until we are all sick of fly helicopters.

We can always add clever things to it later...

Once again, thanks for the input Mart (and everyone else) it's very much appreciated, keep it coming.

CRAN
:ok:

[zeeoo]

Hi cran, just my opinion for the litle it is worth...

ENGINE:
---------
People often suggest using modern automotive engines, with their high level of technology and apparent reliability.
>>>> now most of the common jap engines (even small ones) can get over 200 000 km without any big problem.

Another option is the use of a surplus APU or de-rated surplus turbo-shaft engines. Nonsense, not even going to discuss that!
>>>> apu are available and quite cheap, who is going to overhaul them ? COSTY operators. cheap parts ? no, available "old series" parts ? no, unless you can really operate a recent apu, i would forget that. btw gearing is heavy and costy and R&D hungry.

Modern 2-stroke Engines; light, cheap...but unreliable.
>>>> a FAA certified 2 stroke, could be as reliable as a lyco, but 2 strokes are nor FAA aproved, because no one would certify a such endless gas pit.

Motorcycle engines? Again you would need to thrash them, so reliability and longevity is a problem.
>>>> wrong, the suzuki bandit is well known for its reliability and availability, you told about using automotive parts ? it is a good example.

Modern aero-diesels? None of an appropriate size, generally heavier, very expensive to buy and unproven reliability.
>>> the dieselis i heavier, but lowers the costs in a significant way over time, not for recreationnal local flights, BTW it has a huge torque.

How about a VW-derivative as used by drag/street racers and fixed wing guys? Possible and definitely cheap, but I have serious reservations about the reliability.
>>>> cheap if bare ! costy and unreliable if custom prepared.

How about a radial engine made out of VW-parts? Again proving the reliability is the issue.
>>>> R&D it..

FUSELAGE CONSTRUCTION:
------------------------------
i agree for composites, but not single skin hulls > heavier and costy than tubes, but nicer.
why didnt anyone had the idea of cheap honeycomb ? light, stiff, easy to assemble.

ROTOR SYSTEM(S):
---------------------
When you said rigid, did you really mean rigid or articulated or really rigid like the BO-105?
>>>> th BO105 is called rigid but behaves like a semi-rigid. the blades endure bending.

3-bladed articulated hub but in my mind it is not the way to go.
But what about the substantial additional cost, weight and complexity.
>>> i disagree, the ecureil proved the 3 bladed design can be 40 % lighter, 40 % cheaper and 40 % simpler

What about ground resonance?
>>> the same as in an articulated, with less risk due to semi-rigid setup.

SEATING CONFIGURATION:
-----------------------------
I'm glad you like the tandem concept as there are some serious technical benefits for a two seater in this configuration!
>>> i love this config but instructors will stay away from this as thay like to have their students aside, that would mean double instruments panel.

GENERAL REMARKS:
----------------------
classicism vs innovation is a bad struggle.
accordding to ones, nothing can be done better than existing... :(
and others just dump everything old going in fully-rigid-innovating-over-engineering-thinking.

i m not an engineer, just giving an arrogant opinion :D
thanks

[CRAN]

Thanks Zeeoo,

That’s not an arrogant opinion, it's a useful one!

With regards your remarks on the use of composite; I had taken the word 'composite' to include all of the common implementations including sandwich panels - sorry if this was misleading.

I disagree with your remarks about automotive engines, those 200,000 km are all at a very low power settings with only short duration bursts of high revs and high power, a helicopter application would require that the engine (either automotive or motorcycle) be used close to maximum continuous power for the vast majority of the time and would lead to serious reliability problems.

The Star-flex rotor system was a great success for Aerospatiale, however the 40% cheaper, lighter and simpler is relative to a traditional articulated hub of the same size, NOT a two blade teetering system, the teetering system can be almost an order of magnitude cheaper! Both the starflex hubs and the more recent spheriflex hubs are excellent pieces of engineering, but i'm not convinced they are appropriate for a bargain-basement kit helicopter.

I don't think the struggle between tradition and innovation is quite as big a deal as you make out. One must innovate to succeed when there is strong competition and the product must have that extra 'x-factor' to win the business. However, this is not the current situation for the kit helicopter market. To gain a 95% market share all you would need to do is have a competitively priced machine, that was well engineered, safe, reliable and attractive and you simply don't need risky technologies to achieve that.

Keep the comments coming guys, this is all good stuff!

CRAN
:ok:

[handyandyuk]

Just as a thought hopefuly in the right general direction, how about the idea of incorporation of already proven parts or subsystems as a possible route to some degree of cost saving.
The specific direction I'm thinking would be using something like the Firescout UAV as either a starting concept or even going as far as thinking of incorporation of subsystems ie rotor system, drivetrain.
Maybe I'm miles off, maybe it has possibilities. Either way worth a look perhaps ?

[CRAN]

Handy,

It's a very good point and one that has been made privately by a number of people. Technically, there are obvious advantages to including existing and proven hardware into a budget design; it reduces the development time and cost and gives you a high degree of confidence that the machine will work properly. However, components from certified aircraft or derivatives of certified aircraft are not cheap. Maybe someone here can tell us what three blades from a S333 cost, maybe even the cost of the hub. My guess is those components alone would cost as much as a Rotorway!

Aside from this, would a reputable manufacturer want to risk there reputation on such a venture? If it was successful would they want to risk losing sales to private owners?

Although clear benefits exist for incorporating existing hardware into the design the cost and willingness of other companies to co-operate are likely to render it impossible but it would certainly be worth running it past them.

CRAN
:ok:

[zeeoo]

thanks Cran
check this : http://www.helips.com
these guys are serioursly challenging big parts of the market..
and hen you look at who they are, i feel like a very very little worm...

don't think i'm a downer, some people here know what it try to build.

thanks

[CRAN]

Thanks for the head's-up zeeoo, unfortunately I don't speak any French whatsoever! What ever happened to Bruno Guimbal's 2-seat machine the Cabri G2? Any ideas?

Any chance of an English summary?

Cheers
CRAN
:{

[zeeoo]

oops Cran, sorry, don't cry for the language :sad: , cry for the aircraft they are going to develop :}

you're right, i found this site searching for guimbal's two seat to have info about the rotor.
his helicopter has flown fine as far as i know, and i suspect he is a part of the helips crew (they are all ex-eng from aerostatiale-eurocopter) and his "cabri" may be in the backyard ;).
I think that, if they go into business, an english version will be mandatory.
cheers

[CRAN]

Zeeoo,

I don't think there is any need to reach for the cyanide just yet! I have seen many, many projects like this come and go without ever bringing anything to market!

We will have to wait and see.

CRAN
:ok:

[zeeoo]

You're right Cran... time will tell, but i think eurocopter funds a part of their activity as they are retired.

For your colllective project, go ahead and like others told me : "GET BUSY".

I will not be a basher, but i like to tickle statements :} just like others like to tickle mine (positively).

good luck to all of you and : wrenches up !!
cheers

[Dave_Jackson]

Humorously;

(1) RELIABILITY & SAFETY
(2) CRASHWORTHY AIRFRAME
(3) LOW, LOW COST
(4) SIMPLE LOW MAINTAINANCE REQUIREMENTS
(5) PERFORMANCE
(6) APPEARANCE & FIXTURES

http://www.unicopter.com/Temporary/Hot_Air_Balloon.gif


Seriously;

If the intent is to end up with a slightly improved rotorcraft, consider buying a used Robinson R-22 or Rotorway and then start modifying it.

~ alternatively ~
If the intent is to end up with the lowest cost rotorcraft, consider buying a used Robinson R-22 or Rotorway and then doing nothing to it.

~ alternatively ~
If the intent is to end up with a better rotorcraft, consider buying a box and then stepping outside of it. :8
Without one or more significant improvements, any new rotorcraft will be, at the best, nothing more than just another one amongst the few. IMHO, any significant improvement to rotorcraft must start by improving the rotor of the craft. The fuselage and the engine are secondary appendages that hang from the rotor. ;)

[zeeoo]

hi dave,
your answer is surprising to me, i know you're a rotor man but... IMNHO, for me, it is a all in one project.

you can have the better rotor, but desserved by a bad/heavy/costy engine it is a looser.
Same thing with the fuselage.

if some drivers love to know their car has the last generation "Xmagic", a lot just like to feel good in a comfortable car.
Depends on who the project targets : a mech enthusiast or a final user.
The genius of a good invention is that it can be forgotten by the user.

thank you

[Dave_Jackson]

zeeoo

Your points are valid.

You say; "Depends on who the project targets : a mech enthusiast or a final user."

My first post in this thread was " As an initial step, what about developing an acceptable list of the desired uses for this helicopter?". The response was underwhelming.


You say; "you can have the better rotor, but served by a bad/heavy/costly engine it is a looser."

Currently, the statements ' a cheap reliable rotorcraft' and 'a lightweight reliable reciprocating engine' are both oxymorons. But, the rotor design is in the domain of the rotorcraft manufacture. With limited exception, the engine is a buyout, and every helicopter manufacture selects what they feel is the best available engine, at the time, for their craft.

The current target of this thread is the Robinson R-22 yet the proposed engine is basically the same one that Robinson uses. This does not represent a price or a performance advantage. :{ The advantage must come from the rotor (or rotors :O ).

[Genghis the Engineer]

A couple of technical points.

Firstly Tandem seating isn't that hard to achieve, you put the Captain's (student's) seat in the front so that - which will always be occupied, will always have a similar effect on CG. The second seat and fuel - which will vary considerably more, must be located as near as possible within the CG range. Look at any 1930s tandem fixed wing aeroplane such as the Tiger Moth for an example of this.

Secondly, I hate Lycoming engines - they are 1940s technology, too heavy, too expensive, and too thirsty. If I were picking an engine for a new "from scratch" helicopter design, if I could get away with under 120hp I'd look at the Rotax 914 (http://www.rotax.com/en/Engine/2004/Aircraft/Engine.Models.htm) (which is available certified) , but beyond that I'd look seriously at one of the new breed of lightweight turboprop/turboshaft engines such as the Walter 601 (http://www.aerocompinc.com/engines/walter/index.htm) (also http://www.east-air.com/tech/m601d.htm). Whilst I'm quite fond of them in fixed wing aircraft, I agree with others that 2-stroke isn't the way to go, the specific fuel consumption will be crippling for a rotary application.

G

[zeeoo]

Dave

ok, if targetting the R22, begin with a list of "not to do" :}
personnally i would do a list of what is very good in some choppers, a quick try :

- rotor : eurocopter astar or tiger
- fuselage : ec120 or bk117 for aside.
k max , tiger , cobra for tandem (the straight lines and thick tail allow a simple and rigid structure.
- tail rotor : fenestron, no notar
- skids : ec120
- engine : no idea, depends on overall weight but piston could be cheaper than a turbine.
- avionics : a digital central, cheaper

tell me if you think i hijack your thread dave,
thank you

G,
it is a good spot :}
why not a morane renault ?
I read 914 cannot endure more than 5 minutes of supercharge, a turbo diesel engine can sustain turbo usage.
For G centering/compensating, a suggestion : use the battery in the tail, mounted on adjustable skids..
thanks

[Genghis the Engineer]

There's a Certified 914 operators manual here (http://www.rotax-owner.com/manualrev/10_11_2004/opman914.pdf) , this gives a MTOP of 84.5kW / 5,800 RPM / 114 hp, and an MCP of 73.5kW / 5,500 RPM / 100 hp. It doesn't say so, but I think that Rotax normally follow the general convention of MTOP as 5 minute power.

I've sat through a few presentations by Mark Wilksch, who knows a thing or two about diesels in flying machines. He's of the view that below about 120hp in a fixed wing a Diesel cannot compete on power:weight with a good 4-stroke SI engine such as the 912/914. I'd venture that because of the rather higher continuous power (and thus fuel consumption) requirements of a helicopter, that threshold power is going to increase. That said, if you are looking for a Diesel, the WAM 160 (http://www.wilksch.com/WAM-160.htm) might be a good starting point.

G

[zeeoo]

Hi G
Your link looks interesting, i'm starving for a 100 HP model of this one. i stay beyond the 100 hp limitation of european mono-UL classification.
About small diesels, they weight more, but their power is effective even in altitude and the mass of fuel needed to perform the same path is less, so weight to power ratio is not so bad.
In my airclub, there are 2 kitplanes projects started (same model), both with the dieselis, actually the 2 engines are "secretly" modified by a school, i asked to see them but the owners where not here, so i couldnt have access to them.

they are GM-Opel 1.5 L dieselis, rated to 80-90 hp, i will try to post more.

Just a general consideration about innovation/copy :
Japan, after ww2 didn't have a strong industry and certainly not the actual technological advance. I only can speak for automotive, but in the beginning they had a simple attitude : copy the good existing designs (so came the myth or the photographer-jap), the japanese just spent a lot of time on the automotive exhibits and observed what solutions worked fine..pictured them and copied them.. tha R&D power came after.

i would suggest to do the same for an helicopter : observe and copy existing solutions.

for the rotor : copy the starflex, bruno Guimbal copied it (he is one of the dsigners of starflex BTW) and it just worked fine on his 2 seat Cabri..

I am not an engineer, so , i dont challenge other eng with new theories/ideas, i just ask my self "how can i do this in a simple way", and, not to be pedant but, somtimes, looking down, you find a nugget.

the good example is BD5 development team : they spent a lot of time and money to resolve shaft whirl and torsional resonnance.. when a simple mech told them "if i was me i'd mount a freewheel"..
Damn ! sometimes eng are so high that they dont see where they step...
(thanks andre for the link)

thanks

[widgeon]

One problem with the Starflex is life , many of the components are limited to 2200 hrs though with a much lighter helicopter I am sure the 4000 hr target could be met.
From a maintenance perspective target should be all inspections up to annual can be carried out by the Pilot .i.e you take your helicopter in to the shop once a year for routine maintenence .
All critical parts should be on condition and TBO for dynamic components ( hey lets include the engine too ) should be 4000 hrs.

[CRAN]

This thread has certainly caught people’s attention! Keep it up folks!

Dave,

In response to your comments first. I am quite an admirer of your intermesher work and so will say nothing to discount this, nor will I argue the point that the first priority for a rotorcraft manufacturer is to create a good rotorcraft ~ of whatever configuration necessary.

However we must again return to the first point I made on this thread:
WHAT ARE WE TRYING TO ACHIEVE? KIT (WITH POSSIBLE PATH TO CERTIFICATION) OR ENTRY LEVEL COMMERICAL HELICOPTER?

If it’s a new commercial helicopter then you are correct, as is zeeoo, that there must be a significant improvement over the existing products else you're going nowhere fast. (Pardon the pun) Such improvements would include:

- Engine Technology
- Rotor Technology
- Structures Technology
- Avionics & Systems Technology

However if it is a kit, then a substantially improved rotorcraft can be designed over the three (practical) competitors R-22, RW 162F and Safari, simply by employing the low risk, low cost and low time-to-market strategy that I suggested. The reason I suggested this in the first place was I felt that our community would benefit from a reliable, low cost kit helicopter that they could own and maintain themselves. Remember unless one was willing to pay for such a project themselves, then you have to be able to convince would-be sponsors/customers that you will deliver TO A REALISTIC DEADLINE and high-risk approaches are a sure-fire way to scare such people off; certainly in the UK.

In response to Genghis and Zeeoo regarding the engine discussions:

G: Believe me, I also detest the Lycoming engines and their knock-offs, but when you plumb the numbers into a helicopter performance analysis then you soon see that few engines come near them. You are right about using the Rotax, but at 100hp you’re looking at a high performance one-seater or a very low performance, low payload 2-seater. I'm not convinced that there is a market for such a machine...

However, these guys are: www.dynali.com

I am a big fan of the Wilksch engines, I think they are thoroughly well engineered and based on a sound concept. Unfortunately the 120 hp unit is only good for a one-seater and the 160 hp unit not ready yet and if it was I fear any 2-seat rotorcraft based on it would be both short of payload and performance, but its certainly viable. Your comments about the Walter engines are interesting, though with a BSFC of 0.65 lb/hp-hr that engine is certainly not 'contemporary technology', an aero-engine of that size should easily achieve 0.45 lb/hp-hr with today’s technology!

Zeeoo, those Opel-GM 1.5l diesels will certainly be cheap, but you'll find them rather heavy for a helicopter!:E

This is a fascinating debate, so keep the posts coming!

Cheers
CRAN
:ok:

[zeeoo]

Cran,
check this one, http://www.dragonfly.co.nz/
it has been on the market for about 10 years.. never heard a bad comment.

Yes, dieselis are pretty heavy, I'm not going for that, actually, I didn't take any decision, I would trust HIRTH F30 or H30 engines, but they seem to have serious problems like plug spitting and a peaky power response, but they are cheap and powerfull.
Maybe some improvements could be fine.

I actually investigate in fitting a suzuki 750 bandit.
Yes, I go for a one seat gyrocopter. Building commencing in Jan 2005.

Dave, look at the dragonfly rotor and tell me it doesn't look like something you saw.. does it seem complicated ?

Thank you.

[jellycopter]

Cran,

What's wrong with the reconfigured Generator turbines like the Solar T62? My understanding, which may well be wide of the mark, is that the Solar engine is 150 hp and quite light. Yes it would need a gear-box and probably some FCU work which would add to cost and weight, but haven't these engines been proven beyond doubt in their existing stationary applications? Surely they must be nudging a tweeked Lycoming in terms of cost but are way ahead in terms of technological advancement and probably power to weight ratio.

In terms of marketing a 'kit', I think it would be more attractive if turbine powered. As one of a very small band of kit helicopter owners, and flyers, who has experienced 'kit' engine unreliability first-hand, (on several occasions!), I think the turbine is the way to go.

J

[Genghis the Engineer]

This got me thinking, taking a baseline as a Continental I0-360 (since I happened to have the data to hand) that is a 6 cylinder air cooled 4-stroke, weighing about 148kg installed and generating a maximum of about 210 hp (according to my data book).

The first radical question I asked myself, is what about a twin - I know it's more complex, but it's worth asking the question at-least. So a 912s generating 100 hp weighs roughly 65.5kg installed. That's 131kg for two - or in other words two of these, plus an appropriate gearbox is not going to be all that different to a Continental in terms of installed mass. However, here's a bit of a clincher - they cost about £7k each, so that's £14k for a pair of zero-lifed engines, let's say £20-25k once you've sorted out mounts, fuel system and gearbox. Round numbers, that's the same as the cost of reconditions IO-360, before you add in the gearbox cost; so it might just offer a bit of a saving.

However, the ideal would be a turbine with similar power to the Lycontinental I'd venture. Interestingly the same data book threw up http://www.sea-plane.com/product_details_turboprop.htm ; which according to the data book generates 230hp, masses about 60kg, and will cost around £25k again. Notwithstanding that I know nothing about it, and am naturally reluctant to ever suggest wrapping a new airframe around a new engine - if it were proven, it might be a nice powerplant to wrap your shiny new 2-seat helicopter around.

So the bottom line seems to be you are likely to be spending about £25k on a powerplant regardless - and massing around 150kg for a piston engine, or maybe 90kg less for a turbine?

G

[zeeoo]

G and jelly,

an APU sounds fine in terms of performance and reliability. Turbomeca has several small models.

But some question :
- what about the maintenance bill , do you know a turbomeca or allison workshop near your home ?
- replacing plugs or some minor parts on a piston engine can be done by quite everyone, if accepted by the manual. What about a turbine?

If you target an untralight 2 seat with a turbine, you target people with some financial means, not the "poor" tubes-n-bolts builder. Doing so, you will chalenge used helicopters and the choice between used but proven swheitzer or h300 will not be that easy.

for info : I had the occasion 10 years ago to buy a used alouette II (5 seat) from a sale (of 10 items) from french ALAT, they were all zero life but sold with the complete spare parts set for about 120.000 F, about 20.000 euros each. Alas I didnt have enough money at this time, not to buy it but to repair it.
BTW, a lot of ag sprayers dont like turbine aircrafts for that job.

If you plan to market it, maybe the very first job is to list existing machines, prices, sales, + and - and to try to do something covering BETTER the targeted market.

thanks

[Genghis the Engineer]

I have some reservations about the use of an APU. Firstly they are not generally designed for very long running lives - in most aircraft they are shut down once the mains are running. Secondly, they operate at very high speeds - generally not far under 100,000 RPM. The noise and gearing implications of that are problematic. I certainly remember doing some work on the Saab Gripen where my perception was that the APU generated 4+ times as much noise as the two main engines at idle - certainly you couldn't be within about 50 yards of the aircraft whilst the APU was running without ear defenders, whilst you could be stood next to it (albeit in some discomfort) without whilst the two mains were running.

The Aero Adventure engine is rated at 65,000 RPM which is still very high, but at-least a factor of two below, and one assumed more amenable to soundproofing.

G

[bugdevheli]

WANTED air cooled motorcycle engine suitable for convertion to diesel and dry sump. 3000rpm max. all replies to bug please, plus price and availability.Also required. Epycyclic gearbox to fit the above when mounted vertically , 6 to1 reduction on the top output shaft and 1 to1 on the side output shaft please. Will collect immediately.

[Genghis the Engineer]

The engine you want is almost certainly a Wankel.

However, Norton who were producing them until the mid 1990s got rid of all those projects sadly. Similarly Midwest who were trying to develop similar engines at Gloucester then somewhere in Germany are no more either.

However, a brief trawl around the web found this firm (http://www.atkinsrotary.com/index.php?pag=9) who might just do exactly what you want, although a search on "Mazda rotary" throws up several more.

G

[bugdevheli]

Genghis. Thanks for the info. These rotaries will not convert to aircooling, due to internal water channels. Bug.

[zeeoo]

Bug, you make me think...
A french moto manufacturer did a diesel model.. but long time ago, and i think all this is gone in dust..
What about the Daimler Smart 2 troke 3 cyl diesel engine ? an aviation version was made by a german UL manufacturer, I don't recall the name ..

[Dave_Jackson]

Genghis,

As you say, the Rotax engines may be one of the better engines for very light rotorcraft, but it has a problem that goes beyond the actual engines.

The installation manual of Rotax engines state "This engine shall not be used on rotor wing aircraft (helicopters, gyrocopters, etc.) or any similar craft"

B.J. Schramm and Rotax were not on talking terms because of Schramm's desire to use Rotax engines in his Helicycles. The CH-7 Kompress uses a Rotax 914 but the helicopter is sold without the engine. This is a detriment for any helicopter that intends to have large sales and eventually become a certified craft.


Zeeoo,

" Dave, look at the dragonfly rotor and tell me it doesn't look like something you saw.. does it seem complicated ?"

Yes, it looks familiar :). Superficially, it also appears to looks like the Scorpion and the Rotorway hubs. CRAN has asked for " Benign reaction to low-g flight " This implies a rotor that is somewhat beyond the primitive teetering rotor.


There are numerous one and two seat helicopters out there. All could be 'tweaked' into being something slightly better. None of them will take Rotorcraft to a higher plateau.

Consider the oxymoron of 'low price and superior features". This is not a question of which comes first - the chicken or the egg? It is simply and loudly;- "build a better mousetrap and the people will come to buy"

I strongly believe that;
1) Low price will ONLY come about when the helicopter is mass-produced. (think Henry Ford)
2) Mass production will ONLY come about when a helicopter has shown superior features.


It's the rotor, it's the rotor, it's the rotor. ---> It's the hub, it's the blade, it's the configuration and its the flight-controls. :oh:

[zeeoo]

Give me 70.000 USD and i will market a single seat compound.
anyone?
Wow, it feels so good to be arrogant ! :}

[VP959]

G,

That engine from Aero Adventure looks very much like a modified APU to me. Not withstanding the relatively high power output, I'd lay money that the core originates from such a unit.

The Atkins rotary is a Mazda RX wankel, converted for aircraft use. Probably the best expert on these engines is the chap that designed and built my BMW EFI unit for me, Tracy Crook (see http://www.rotaryaviation.com/).

There's no obvious reason as to why a 12A or 13B Mazda can't be mounted vertically, the rotors are oiled via oil in the fuel and the rotor shaft and gear lubrication should be able to be modified. Tracy has flown an awful lot of hours on his RV using one of these Mazda engines, and is the sort of helpful chap who would advise on other applications, I'm sure.

VP

[zeeoo]

VP,
I'm with you, Mazda engines are interesting..
And about your BMW, do you mind posting more infos ? or a link please ?
Thank you

[Spaced]

Faster, cheaper, better. Pick two.

Im surprized that rotaries only got a passing mention here.
This is what I have been looking at for my project, they seem perfect for aviation.
A NA 12a is good for about 120hp, and a 13b about 150. With mods good for much more.
The best thing about a rotor is that once running, they tend to keep going. Even with the failure of a rotor they still produce about 40% power.

[CRAN]

Jellycopter,

Everybody wants their helicopter to be turbine powered! If only it could be done for the required cost...
The APU derivatives have a number of disadvantages, the most importance of which is that they have a specific fuel consumption of around 1.2 lb/hp-hr that means they burn almost three times as much fuel as a modern piston engine (almost four times as much as a diesel). Therefore an R-22 equipped with such an engine would burn 27-30 US Gal/hr of fuel per hour. Hence there is a huge fuel-weight penalty. This problem is a result of the fact that these machines tend to use low-pressure cycles, with pressure ratios in the region of 3:1 which is far too low to be efficient without a recuperator. In addition, the engines are really rather heavy, in turbine terms. That is really not an avenue you would wish to waste money on i'm afraid. Though plenty have...

Genghis,

The seaplanes.com engine is an interesting one, I have been following it for three years or so and they don't appear to have done much. I believe they sourced the engine from Argentina:

http://savoiapower.8k.com/labala.html

[The picture shown was the original one used on the seaplane website]

The interesting thing here is that the pressure ratio is higher at 5 and so the engine can achieve more reasonable fuel consumption (albeit only at high power settings) of approximately 0.53 lb/hp-hr, which is not bad by contemporary standards. (The RR C250 varies between 0.6 - 0.72 lb/hp-hr)

But as Genghis says we know little of the quality of the engineering or the reliability of the machine...but it only weighs 17kg for 230 hp!

Bugdevheli, I’m aware of a project by the Royal Military College of Science (Cranfield, Shrivenham Campus) that modified a Kawasaki engine to run on JP4 & JP8 in order to satisfy the military single fuel policy, this engine is know in production and may be a good starting point - if only from a technology and approach standpoint.

http://www.drive.cranfield.ac.uk/cfml/dieselmotorbike1.cfm

Spaced et al:
Have you spoken to my neighbours regarding Wankel engines?
http://www.uavenginesltd.co.uk/index.php?id=393

Incidentally, I still have the same concerns about such engines; longevity and reliability when operating at high power settings for extended periods...be careful chaps.


Dave,
Of course ultimate low cost is never going to be achieved until rotorcraft are mass produced ~ but that will never happen. They are simply not the right vehicle, either in traditional or novel formats to be used for mass transit. They use far too much fuel, make far too much noise, will always offer too many opportunities for people to harm themselves and others. In addition, a large volume of such aircraft would require an enormous control infrastructure to provide collision avoidance and routing. [I’m aware of free-flight etc, but it’s a long, long way off.] This would take away all of the benefits of point-to-point VTOL. In addition, mass-production or not, we need to focus on operating cost rather than purchase cost because for commercial helicopters it the operating cost that is the real problem that prevents the helicopters market growing, not the purchase price.

One other point; if people really wanted a three-bladed rotor then I have no problem with that as long as we collectively accept that it will cost more! Dave, in response to your comments regarding low-g flight, I feel that for a fair-weather flying kit helicopter, sufficiently beniegn low-g behaviour could be achieved by configuring the aircraft in such a way as to reduce the role-rate in low-g flight - put the tail rotor in the right place! i.e. similar to Jet Ranger.

CRAN
:ok:

[Dave_Jackson]

CRAN,

The points you bring up have merit. This is particularly true if the objective of this project is that of producing 'just another helicopter'. If the objective is to produce a product that stands out from the pack, then this product must have one or more superior features.

The engine is anybody's guess. One idea that we have previously discussed is the installation of two smaller engines for reliability.

The fuselage, IMHO, must be carbon composite construction, with imbedded Kevlar in the shell around the occupants. The strength of carbon composite is far superior to metal construction because the plies can be laid up to suit the structural loads. The price of carbon cloth is continually coming down.

Empty weight is the albatross of the helicopter. Consider the advantages of weight reduction due to the use of composite construction. Consider a 70-kg saving in the fuselage weight of a 700-kg craft. This is a reduction of 10%. Simplistically, it now means that all of the other components can now be 10% weaker and thereby 10% lighter. This reduction of the weight of the 'other components' now means that ........ Basically, it is a recursive diminishing reduction of the craft's empty weight.

Lastly and most importantly, the rotor. You have mentioned the efficiency of the 2-blade rotor and you say; " sufficiently beniegn low-g behaviour could be achieved by configuring the aircraft in such a way as to reduce the role-rate in low-g flight - put the tail rotor in the right place! i.e. similar to Jet Ranger." Perhaps this may be valid.

Alternatively, here is a new and crazy idea from the Department of Demented Designs;
Take the Robinson's 3-hinge teetering rotor. Add a simple linkage so the coning hinges cone in unison. Link the coning angle to a hub spring (http://www.synchrolite.com/B329.html#Hub_Spring). The smaller the coning angle <--> the stronger the moment of the hub spring, and visa-versa. The objective is better control over a lightly loaded rotor while not increasing the 2-P vibration during forward flight.


Just food for thought. :ok:

[zeeoo]

Dave, with great respect for your work, I try to argue on what I have seen, readed from other designers.

The engine is anybody's guess. One idea that we have previously discussed is the installation of two smaller engines for reliability.
>>>> as a great part of the final weight the engine IS a critical choice, my personnal opinion would be to start from a given engine. and build around, I Know my view is not good but it hasn't been tried.
>>>> twin certified turbines fitted by a good manufacturer are a factor of reliability, but small engines fitted by "amateurs" (sorry it is not an insult, I just miss the right english word) can a be a factor of failure as you have to r&d and fit extra non-standard devices.

The fuselage, IMHO, must be carbon composite construction, with imbedded Kevlar in the shell around the occupants. The strength of carbon composite is far superior to metal construction because the plies can be laid up to suit the structural loads. The price of carbon cloth is continually coming down.
>>>> so does epoxy resins, much much cheaper and easy to use. Btw carbon may be too stiff for certain usages. Why Kevlar ?the role of a crash-proof structure is to absorb shocks, so, to break and crumple, not to resist, it has been very welle understood in the automotive industry with coltrolled-folding bodies.
chasing high end technologies is IMHO not a way to lower costs.

means that all of the other components can now be 10% weaker and thereby 10% lighter.
>>>> wow.. whitch componants ?

>>>> rotor : why not a 2 bladed semi-rigid one ?


Take the Robinson's 3-hinge teetering rotor. Add a simple linkage so the coning hinges cone in unison.
>>>> i thought the efficiency was linked to a low coning ?
a symetrical coning means less lift on the retreating blade, and , from my poor understanding, this is not the goal of a teetering rotor.

while not increasing the 2-P vibration during forward flight.
>>>> the 2/rev shake has been successfully smoothed on gyros by adding 2 simple springs on the teeter rod ends.

Why don't you consider buying (for example) the dragonfly blades and grips and fit them on a semiriigid 3 bladed hub ?
What about the blades ? The hub is fine, right, but you could have an iron-stiff hub is the blades and their links were well thought, no ?

Bash me like the arrogant newbie I am (oh yes ! hurt me :p) , but leave arguments, i will keep them for my personnal use.

cheers

[Dave_Jackson]

Zeeoo

Some quick answers.

"carbon composite construction, with imbedded Kevlar
Carbon brakes like glass. Kevlar makes it brake like safety glass.

" Btw carbon may be too stiff for certain usages. "
In those locations use fiberglass.

" 10% lighter. >>>> wow.. whitch componants "
The engine, the transmission, the rotor .......

" >>>> rotor : why not a 2 bladed semi-rigid one ?"
The pros and cons of different rotors ain't available as a quick answer.


"oh yes ! hurt me :p "
Kinky. Perhaps one of the female pilots would be better qualified. :D

[zeeoo]

Dave,
funny, I would have a female's opinion on that.

seriously, i agree with the kevlar use, but the stiffness isnt gone even with kevlar, why not sandwich roving/foam/rOving or honeycomb.

And about blades technology ? efficient blades are the key to gain efficiency so payload. All i have read bout that seem to agree that a good blade design is a major key of improvement.

If weight could be gained on chassis, I would tend to reinforce the rotor safety/lifetime and a little engine de-rating.

thanks

[CRAN]

Dave,

The configuration that I proposed offers the following improvements over existing kit helicopters:

(1) Improved payload (300kg)
(2) Improved performance (speed and range)
(3) High inertia rotor system - benign HV curve and behaviour in autorotation
(4) Massively improved reliability
(5) Massively improved crashworthiness
(6) Bullet proof, de-rated, fuel-injected engine with realistic 2000hr TBO
(7) Reduced 'real-life' operating costs
(8) Dramatically improved appearance & external aerodynamics
(9) Reduced & Simplified maintenance
(10) Improved handling qualities
(11) BCAR-VLH/EASA-VLR compliant design

Such a configuration, would allow would-be R-22 self-fly hire pilots, to own and maintain (either individually or in small groups) their own helicopter. A helicopter that has been specifically designed with the low-time pilots in mind.

Just another helicopter? :confused: I don't thinks so, but I guess i'm biased!


We can the compare the configuration to the certified market leader, the Robinson R22 Beta II:

My configuration offers:
(1) 30% More Payload (2x225lb PAX & 3hrs Fuel)
(2) 30% Higher Cruise Speed
(3) Traditional High Inertia rotor (Similar behaviour to Jet Ranger)
(4) Fuel Injection - NO CARB ICING
(5) Dramatically improved crashworthiness
(6) Improved 'less-skittish' handling qualities
(7) Approximately 40% the purchase cost of a R22
(8) Approximately 30% the operating cost of a R22

Just another helicopter? :confused: I really don't think so. :cool:


HOWEVER, if 'Just another helicopter' means that the aircraft is financially viable to develop and market on a tiny budget in minimum time, or that it is sufficiently familiar for people to believe that they can build and fly one safely the I guess you are right - Just another helicopter it is. ;)

There is a place for triple-D designs and large prizes for those that get them to work and indeed I have my own collection of them. However, I believe strongly that triple-D designs have no place in an under-funded kit helicopter project...least not if you what to get something to market.

Dave, your hub sounds great in principal, better than a two blades ~ except on cost. But how will you convince people to bet their lives on the fact that:

(a) It works properly
(b) They can build it
(c) It won't break

...and would you be confident enough to do so? Remember, limited budget, limited testing, limited confidence.

Surely under circumstances such as these (realistic ones) it would be better to rely on a hub design developed in the 40's and used safely ever since - even in the worlds safest single engine aircraft? Similar argument for the configuration and the engine.

CRAN
:ok:

[Gaseous]

Cran, Dave,Zeeoo

All of this would be possible if it wasn't for the restrictive regulation and bull**** imposed on the industry by the CAA and their like across the world. The last thing that the regulators want are the skies full of Joe Public flying around in cheap, good machines. They are frightened of the airways ending up like Britains roads. Keep it expensive and exclusive is their ethos. Mass production would reduce costs and improve quality but they are terrified of it. It is incomprehensible that in the 21st century, new aircraft are being made with carburettors and magnetos - and they wouldn't be if there was less regulation. How many truly new light helicopters have come on the market in the last 20 years? Not so many- and thats just the way they like it.

That is why we are forced to fly around in 1940s technology.

[Dave_Jackson]

CRAN,

Your list of eleven objectives certainly does not describe "Just another helicopter". A craft with all these attributes will be far more than that. The concern, in my opinion, is not the objectives. The concern has to do with the means or the ability of implementing all, or most, of these objectives.

To build a craft that does more than "Just another helicopter" requires more than a collection of yesterday's technology. I doubt that all or even most of these objectives can be met solely by stepping down to the Very Light Rotorcraft category.

In addition, there are others looking at the same category and market. The spoils will go to he who has the better craft. (or perhaps the better marketing :yuk: ).

______________________

Since you asked; ;)

We probably both agree that 3-blade rotor will not provide as good a thrust/weight ratio as a 2-blade rotor. In addition, the increased rotor moments caused by the hub spring will necessitate a stronger (& heavier) craft. The advantage, of course is a faster and more positive cyclic control.

"Dave, your hub sounds great in principal, ...... But how will you convince people to bet their lives on the fact that:

(a) It works properly
(b) They can build it
(c) It won't break"

CRAN, I'm not trying to sell this 3-blade CVJ+HS rotor. It may not work in the real world. But, I feel good enough about it to build one and have fun testing it. This testing may eventually satisfy the above (a) and (c).

A solution for (b) may be to copy the method used by the world's cheapest rotorcraft. The full set of Gyrobee plans can be freely downloaded off the Internet, but the rotor hub is a purchased item.

[zeeoo]

Gaseous, you're right.

Dave, take your wrench and Get busy !!

That is what i decided, remember? it is going in january 2005 and a lot of people find my design very attractive.

I will have a lot of fun doing it, but who knows if it will match my expectations...

Hey , did you think about a gyro ? making an helicopter for 2 minutes hovering is not worth the extra expense... make a gyro and make it ultra-short take off (like degraw's gyrhino)...

Gyros are as (or more) manoeuvrable as an helicopter...

thanks

[CRAN]

Gaseous,

You're absolutely right about regulating by cost! However, the BCAR-VLH regulations and the EASA-VLR regulations do allow you to slip in with a kit aircraft at the £40-50K point, with the operating costs as I have described. While this is certainly well out of the reach of the everyday-joe, it certainly puts helicopters flight into the reach of many fixed wing aviators - a market that is 5-10 times larger! In addition, people that currently fly self-fly-hire would be able to buy, build and maintain their very own high quality, high performance rotorcraft. Reducing cost and getting much more than a R22, Rotorway or Safari can offer on top.

Dave,

Thanks for the continued discussion. I agree that we are not going to produce a next-generation rotorcraft by implementing my proposal, but however this was never the intention. The intention was to produce a high quality, safe and reliable kit helicopter that will get private fliers up and flying at the minimum cost, safely. Squeezing, the levels of payload and performance that I have described out of a IO-360 powered machine without sacrificing reliability certainly requires highly skilled engineering, but I have no doubt, it is perfectly feasible, if a little close to the asymptote. ;)

A next-generation machine requires much more, a better engine, a better rotor and better systems, but this will take a lot of time and money to develop properly and in my opinion is that it is beyond the scope of this project.

As I understand it this thread is about building a high quality, low cost kit helicopter that could be available in a couple of years and possibly be certified at a later date via the EASA-VLR (Europe) and Primary Category Rotorcraft (US) regulations. The high levels of performance and reliability offered by the proposal will up the expectations of the market, hence raising the minimum standard required for a manufacturer to successfully enter the market with a new machine and hence put an end to dangerous kit products and inadequate/non-fit-for-purpose certified designs, benefiting all in our community.

Thanks to everyone for sticking with these long posts!

CRAN
:ok:

[Dave_Jackson]

OK forget the rotor :{ ~ for a moment :D .


Weight:

Reducing the weight of the craft's components allows for more of the other goodies (safety, reliability, payload etc.) to be put in. The following is an excerpt from an article in this mornings paper entitled 'Airbus aims to trump Boeing'.

" the company [Boeing] plans to build the airplane [7E7] largely out of carbon-fiber composite panels, which are lighter and more resilient than aluminum, the material from which almost all planes are made today."

This large and ever increasing consumption of carbon will result in a continuing decrease of its cost. If the cost of the first prototype is a serious problem, one might consider the use of timed-out carbon prepreg, or fiberglass with an extra layer or two.

[zeeoo]

Dave,
I would agree more on the "timed-out" thing.
Often, things that were high-tech 2 years ago are considered as obsolete now, but never forget they were high-tech only 2 years ago (ex : computers). If the solutions get more and more sophisticated for marketing reasons, it doesnt mean that you must follow the rythm.. Do I express my self right ?
In other words : if Excell or Word ran fine on a 3 years old computer, you don't need faster to run them, maybe ou could enjoy smaller.

thanks

PS : Airbus are not yet full-carbon, and we, you and all here are not yet Airbus R&D bureau, alas :}

[jimgriff]

Has it occured to anyone that a mega bucks company wishing to plug a hole in the market has just had all it's market research done F.O.C?

[CRAN]

If it means 'big bucks company X' gets something to the market in the near future that fulfils the requirements that we have collectively identified then surely the thread has benefited the Rotorhead’s community.

Chances are though, they will disregard the thread as completely unverifiable information, assume that any 'small project' will fail to get anything to market and so do nothing. In that case then others may choose to benefit from the information generated by our group.

In the vast majority of cases the internet is only a starting point, in isolation it does not represent a reliable source of information as it is not subject to peer review or quality control.

CRAN
:cool:

[RDRickster]

Besides, this is a discussion in theory. There isn't any market research presented on this thread. I get a chuckle when I see young entrpeneurs identify "market research" as browsing the web for a few statistics here and there... mostly from unproven sources.

It takes a lot of work to establish a business, and the folks that start out will usually make less than minimum wage when compared to the enormous effort required to get something off the ground (pun intended). Successful business owners are the ones that get to do something they really love, or build on an idea that is simple and reproducable. I'd rather go with the "something you love" concept.

It will be interesting and fun to see these dreams and thought put into action.

[zeeoo]

RD, You go first ? ;)

[Dave_Jackson]

OK! Due to popular demand, it's back to the rotor. http://www.unicopter.com/7up.gif
Nature's creatures are laterally symmetrical. (Trivia ~ Even facial symmetry is advantageous when attracting a mate.)
Man's improvements are founded in nature.
Vehicles, excluding abnormalities such as motorcycle sidecars and tail rotor helicopters, have lateral symmetry. [/list=1]
The non-rotor related crash of the 3-blade intermeshing Kellett helicopter (http://www.synchrolite.com/0896.html ) and the death of the test pilot put an end to Kellett's intent to build a stronger rotor. Since then, two generations of stronger and lighter materials have become available for the production of rotors with greater rigidity. [list]
Is it not time to take the helicopter up a generation or two?
Is it not time to reconnect with the ingenuity of Nature and the aspirations of Flettner and Kellett?
Is PPRuNe not the place to pull ahead of the crowd? :ok:
Last and least ~ Is this posting a little too brash to be a 'letter to the editor' of AHS's Vertiflite? :O

[zeeoo]

Dave I am ok, excepted with the symetrical thing : see mapple tree fruit.. a perfection in dissimetry.

To progress : ok !
Let's search impromements in the way to GET LIFT instead of improving an old idea such as a rotor :D, what a complicated and dangerous device.. ducted fans maybe? High-pressure jets ?
check kestrel aerospace.. maybe a clue.
cheers

[Dave_Jackson]

Marketability:

The following web page has information on the U.S. Sport Pilot / Light Sport Aircraft Category (http://www.pra.org/news.php). Helicopters are not included at present, but there is the opening for their inclusion in the future. " Helicopters - no value, helicopters are too complex to be allowed under this first issue of SP/LSA rules. "

Those who are considering the production of a very light rotorcraft for a broad market may wish to consider these rules in conjunction with those of JAR-VLR and BCAR-VLH.


Weight:

It appears that the maximum weight for SP/LSA rotorcraft has been increased to 1320 lbs (600 kg) gross, from the previously mentioned 1232 lbs (560 kg) gross. This GW is now the same as JAR-VLR.

One modern 2-seat helicopter that is manufactured out of current materials is the Ultrasport 496. Its empty weight is 575 lbs., its useful load is 605 lbs., and its gross weight is 1,180 lbs (536 kg). This proves that new small helicopters can be (and should be) produced with an empty weight to payload ratio that is very close to 50/50.

The current Robinson R-22 Beta II has a payload of 515 lbs and a GW of 1,370 lbs.. The use of modern materials should allow this payload to be maintained or slightly increased, while the GW is reduced to below the JAR-VLR and SP/LSA ceilings of 1320 lbs (600 kg)


Dave