All i need now is the balls to try it

[bugdevheli]

Homebuilt job
http://i339.photobucket.com/albums/n474/bugdevelopments/PICT0007.jpg

[parasite drag]

What can you do with it Bug, apart from a sneaky hover ?

I'm guessing it doesn't have a permit ?

Other nations are awash with 'experimentals'..but they're useless over here in Blighty

PD

[Heli-Ice]

Does anyone have that big balls?

[helimutt]

I'd have a go at hovering it but i'd prefer it to have a collective. :ok:

[bugdevheli]

The end of the collective is just visible next to the lower part of the cyclic. It is a white disc with a flat on it. Bug .

[iainms]

Bug... that :confused:

[Vee-r]

Surely you can just pick it up...

[HOGE]

Don't forget the Fedora and overcoat when experimenting with new types.

http://www.aviastar.org/foto/vought-sik_vs-300.jpg

[500e]

What are the wheels on rear boom? Please don't tell me its a belt drive to rear fan
I presume the vertical case is a cover for the drive either chain or belt to a X shaft & then a bevel to the top fanny thing and the tail drive is off the X shaft. I presume that is the reason for the steeped pulley in centre of boom.
I have Small .. so will be of no use whatsoever :E please keep me informed as to your continued health, as my granny said to each his own looks well put together though

[MartinCh]

it's budget homebuilt.
No need for angled gearboxes :-)
Belt would do. And you get get replacement in homebase..

[22clipper]

More substantial seatbelt than the Robbies. Be careful. Small choppers remind me of toy dogs, they can have a nasty bite disproportionate to their statue.

[toolowtoofast]

I'm not sure the multiple failure points on the tailboom are necessary - way too complicated!

[ReverseFlight]

I think the size of the carton of juice at the top is disproportionate to the size of the machine.

[VfrpilotPB/2]

Mitigate the problems that you might feel would arise, wear some good bodyarmour and connect the battery, I think I would have a go but what really puts me off is all those drive belts to the T/r , wind blown leaves would cause those belts to come adrift, they look flat would be better if Vees. and short belt connection to drive a lightweight shaft thru a small G/Box

Get some body to Vid it when your trying, Oh and what about tethering it to a couple of tractors, very interesting! Good luck!:eek:

Peter R-B
Vfr

[Matari]

Same machine, but with a different M/R head? Love the BERP blades and skateboards for ground handling:

<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/9nHzHmLghFk&hl=en_US&fs=1&"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/9nHzHmLghFk&hl=en_US&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>

[helimutt]

after watching that video, just a couple of points!

1. are those flat belts driving the tail rotor?:eek:

2. Is this just a wind up?:confused:

3. I've changed my mind!;)

[JohnDixson]

You could call up the Pilots Office at Westland, and I am sure someone would be glad to give you advice on how to proceed.

Thanks,
John Dixson

[onetrack]

I don't know what frightens me more - the cheap, supermarket-style, plastic fuel container, that obviously has passed muster as a fuel tank (please tell me, it's fuel-rated plastic) - or the frightening multiple-belt tail rotor drive system that reminds one of a flat-belt-powered machine shop, of pre-WW1 vintage.

I reckon the life of the whole unit, including the operator (I wouldn't dare call him a pilot - a circus daredevil, would be a more fitting term) revolves around the life of the plastic fuel container - which I would estimate at 3 weeks maximum - and possibly even considerably less, if subjected to strong UV light ..... :eek:

[bugdevheli]

For those of a more technical nature. The small blades in the video clip were only to put a little drag on the drive system whilst testing the tail rotor. The tail drive system was run for several hours at on and a half times its normal running speed. The vee and toothed belts have given no problems to date. Belts provided a lighter method of transmitting power to the tail, negating the need for an anglebox on the boom,helping with the longtitudinal balance. As i have some 80 hp available the extra drag of the belts is not a promblem. The small fuel tank ensures only short runs are possible during testing. Each run is followed by a full inspection of all critical components.The tailboom is extendable via a carbon sleeve, this allows all belts to be tensioned at one go.

[slowrotor]

I like the belts. Should work fine as long as they don't come off the wheels.

Looks cool!


p.s. Hope you have some recent piloting time or dual instruction.

[bugdevheli]

Having only just noticed onetrack,s concern over the fuel tank. Rest assured cobber, it,or rather they, are indeed designed to carry petrolium spirit. I note too your observations as to the pilot,clown,nutter, or whatever other noun you choose to describe yours truly. Permit me to say this is the uk mate. we breed em tough and fearless here. wich is why i shall resist giving you a tongue lashing on this occasion. Peace to all men, and a safe 2010

[biggles99]

Bug,

whether the MK4 ever flies or remains an engineering passion for you, I wish you every success.

The world needs more people like you -- you cheer us all up. Well me, anyway.

And I'd rather be in your machine than in that weird Japanese 4-engines-just above-your-head-thing that we've seen here in previous posts.

Having said that, I think both yours and the Japanese one look great fun -- and there's an American one to check out as well -- the Air Scooter. (I don't know how to add the links).

Happy landings!

Big Ls

[VeeAny]

BigLs

You mean Welcome to the AirScooter Corporation Website (http://www.airscooter.com/) ?

GS

[bast0n]

Bug

Quite simply brilliant. Go for it!

Youth passes - but with luck immaturity will last a life time!

Good luck and best wishes for a simply exciting new year - keep us all posted:ok:

[helimutt]

Seriously, anything you can adjust the c of g of, just to tension the belts? You serious?
You say the belts have been tested up to higher speeds, how about increased loading due thrust from the tail?



Good luck for 2010. I'm all for homebuilds, exciting stuff but I don't think it'll ever fly.:hmm:
If it does, please post the vid up here to prove us naysayers all wrong. :E

[500e]

Yep my .. just got smaller, after viewing vid.

[bugdevheli]

The tail fenestron, blades and sliding guide tube are carbon, the shafts are titanium. The digree of movement to tension the belts has minimal effect on the c of g which remains within limits with up to two inches of tail movement. The belts, blades,and linkages have undergone several hours of full load and movement. to date no problems. I thank you all for your replies, and of course will post a vidio when i have succesfully flown the machine. May i quote Otto Lilienthal It is easy to invent a flying machine, more difficult to build one, to make it fly is everything

[VeeAny]

BugDevHeli

I admire people who have the intelligence and patience to do stuff like this.

I'd love to do something like that.

Good on you.

Gary

[BoeingMEL]

I've waited over 50 years for this...and now I HAVE seen an old bold pilot! Nice one Bug..the world needs guys like you. HNY bm

[helimutt]

Hey Gary, keep a space for G-BXTV on the Griffin Database. Me thinks it'll be there soon enough! :eek:

[bigglesbutler]

Looking at the "collective" I am assuming it is a fixed pitch heli? And your knob that you call the collective is a throttle perhaps?

If that is true then good luck, my model helis were a pain to fly as a fixed pitch machine, there was a noticable delay between inputting power and the aircraft gaining altitude. The normal point for noticing this is when descending too fast and needing to stop the descent and praying it reacts in time.

I'm being anal here but you don't have a Fenestron, a fenstron is what is on a dauphan/ec155 etc, the tail blades enclosed in the tail fuselage. You have a normal tail rotor but I don't know if it has a specific name.

Good luck and be carefull, but we want a video of the outcome good OR bad.

Si

[VfrpilotPB/2]

The Vid of the run up must be the LHD export model, is that why the belts are on the port side?;)

Still like it, but with a few reservations:eek:

PeterR-B
Vfr

[helimutt]

So it looks as if the Rotorheads are pretty much in agreement, as we all seem to like the 'idea' but I have to say, the more I think about it, I feel that Bug is running 3 cans short of a six pack!
:ok:


I'm looking forward to the flying video. Bit like 'A Chopper is Born'!

[parasite drag]

Oi !!!

Lay off the Rotorway :=

[sunnywa]

Bug,

I have nothing but good wishes for your adventure. To build something like this takes a lot of nouse and I tips me hat to you.:D:D:D:D

Good luck and take it slow (and low).:)

[widgeon]

Homebuilt Ultralight G-1 Helicopter (http://www.vortechonline.com/g1/)

And heres one where the plans are 24.95 or 2 for 26.95 , but if you act now we will throw in the graty as well :D

Also note that they will pay for any flight video

[bugdevheli]

I thought i had sort of signed off on this topic, but cant resist. In answer to points raised. Firstly "fenestron" stand orrected on that one. perhaps its impenage or something similar. Second. tail rotor is driven vai pulleys both sides of the boom which are not interconnected. The system will drive on one,or both sides. Any lateral flex in the tailboom is restricted by the belt on the .side that would tend to lengthen. The machine has a conventional collective lever with a twistgrip throttle. It has built in correlation,that can be overidden where necessary. Bug. ps i have a question for more knowledgeable folk than myself. Is it safer to tether the machine for initial lift off, and risk the snatching about at around twelve inches off the floor. or should i go for the full monty,and just grit my teeth.

[Bournemouth Air]

Hey Bug,

I am sure I have seen a Different machine at a PFA Meeting a few years ago. How many of these have you built now

Cheers

[Bournemouth Air]

How many of these machines have you made because this one is totaly different.


Cope Bug 2, G-BXTV, Private (http://www.abpic.co.uk/photo/1199145/)

[500e]

There is a pic from Weston helidays 2008 I think.

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

[bigglesbutler]

The only comparison I can make, yet again with my model heli's, is that learning to fly mine with it tethered was much harder than allowing small hops across the field. I also had the benefit of two wooden rods forming an x under the heli to widen the footprint and thus stop it rolling over. My thoughts would be in the middle of a nice big field, and then do small hops till you manage to hold it in a steady hover.

Good luck.

Si

[slowrotor]

I think it is best to slowly pull it off about 1 inch and then set it right back down before it starts to move sideways or backward. Keep doing that until you can hold a 1 inch hover without moving. Then go a bit higher.

But I am no expert. Expert instruction would help.

[widgeon]

Bournmouth , I see that pic has the provisions for the optional radome :ok:

[Rigga]

Nice design!
Why have you changed the previous round Tailboom to a square section tailboom?

And don't listen to those who've never flown microlights - they're not used to real flying or minimum standards.

Happy New year and the best of luck.

Rigga

[helimutt]

Hey rigga, 'Minimum Standards'?? Wanna bet? PMSL

[Cron]

May I hover it?

I'm only up the road, Halesowen. Got a PL(H).

Cron

[heliprof]

hi !

I owned and flew the deathtrap revolution mini 500 !
If somebody knows what he is doing experimentals can be ok.
but said that, i did not know what is was doing, had just 70 hours and fortune to fly the mini a couple hours and then sold it to complete my CFI.
the mini`s with a turbine must be a blast :} !

fly safe - happy new year !

Rick

[Gaseous]

Bug, Have any of the previous bugs flown?

I watched a homebuilt hover around a field a few years ago. I seem to recall it had a Yamaha 2 stroke bike engine and flew well till it lost a tail rotor blade!:eek: - no one hurt. I dont know if the builder was a Ppruner - I think he might he may have been called Julian. He might be able to help if anyone on here knows who he is and can put you in contact.

Like others I am curious to know why belts were chosen over shaft and gearbox for the TR when youve got the power to lift the extra weight. That said, I dont think the Rotorways have too many problems with a belt drive TR.

Cheers.

BTW, I have flown a few machines over the years straight after major overhauls, rebuilds, crash repairs etc. (certified only). I do it from concrete to reduce the chance of a skid digging in if it starts to go pear shaped. I'd rather rotate or slide sideways than roll over. Spend some time with it at flying rpm and no collective pitch, check the disk moves as expected with cyclic input. Check the tip plane of the blades is not split. Pedal inputs should cause the aircraft to move slightly, again as predicted. You can feel the thrust just twisting the aircraft a bit. When happy,apply a little collective to get light on the skids and check the pedals make sense again. Check the tip plane of the MR blades. If they split with added collective pitch expect vertical bounce in the hover. This is best checked with a strobe and tip targets. Be very careful with cyclic inputs when light on the skids. Be prepared to dump the lever. When happy, go light on the skids to get TR thrust balanced and pull into a low hover. Be prepared to dump the lever. Take it carefully. Probably best to practice this quite a bit and get it hovering right before moving on to any other tests.

Over the years, I have come across assembly, rigging and tracking and balancing problems with aircraft straight out of maintenance. So far the above technique has worked and nothing has got damaged. Its pretty obvious if its not right. The test is aborted and the problem solved. Others may do it differently but this works for me.

Are my balls big enough for the bug? I might hover it but after that you're on your own.

Best of luck.
Phil

[bolkow]

I have five radio control helis, and the least of them looks more formidable and complicated that that machine. Seriously though, if its been checked its got to be as safe as any other machine. Dont tell me that professional heli pilots are falling into the civvy assumption that larger is safer?

[toptobottom]

Bug - Love your attitude!! Go for it man, and as for "...or should i go for the full monty and just grit my teeth?" Grit your teeth, but for goodness sake, don't get carried away and do something you may later live to regret (or worse, you don't live to regret)!! I'd spend a looooong time at a very looooow hover and doing lots of very gentle manoevres before ding anything that could really bite you.

Best of luck with it - would love to come and help if you need another pair of hands!

TTB

[onetrack]

Bugdevheli - I can see where the belt design does have major advantages regarding weight saving, and elimination of the gearboxes, driveshafts & universal joints. I would trust that the belts are aviation grade Kevlar, and not automotive grade.

Belt whip is something that probably needs to be addressed - the distances between the pulleys are quite long, and to eliminate dangerous whip, there are only two ways to do so. One way is to increase belt tension substantially - thus leading to belt stress, shorter life and increased likelihood of failure. The second way is to add idler pulleys to control whip. A third way would be to increase the number of pulleys overall, and thereby reduce the individual belt lengths.

Does this thing actually get off the ground? I haven't seen a video of it actually hovering. I don't believe that too many previous test hovers of chopper prototypes, saw them tethered. Tethering seems like it would place outside forces on the chopper that could lead to incorrect presumptions of stability. Far better to let it fly free, and gather inputs that precisely reflect true flying conditions.

My last question is - what are the plans for a proper fuel tank? - and wouldn't this thing have a very limited range? The weight penalty of a decent fuel tank would seem, to me, to be a big bugbear in the design.

Rigga - From an engineering viewpoint, square sections have vastly increased strength over round sections, when it comes to load-carrying capacity. The sharp corners of a square profile increase strength enormously over the simple round section.

P.S. I've got a thick skin, feel free to savage me all you like, if you feel my comments are too critical. I'm trying to offer constructive criticism, but different people have varying opinons, as to when constructive criticism ends, and destructive criticism starts.
I must say I agree with BoeingMEL, you cerainly look like an old and bold pilot to me. Good luck.

[parasite drag]

"and wouldn't this thing have a very limited range?"

Its range potential is a moot point as it won't be doing anything more than hovering and maybe a sly CAA unaware circuit, IF anyone's brave enough.....

Please correct me though if you know better and think it would be issued a Permit to Test....

PD

[VfrpilotPB/2]

The photo with the rather splendid little heli bug being under the "Deutsche SeeKonig" gives a good example of just how small small really is, the tail rotor of the SK is much much larger than the main rotor on the Bug.

But I still think I would have enough joules to slightly unstick from terra firma, done with much deftness I am sure the traits for such a tiny thing would soon be learnt, after all if most of us can fly the R22 then we are already used to twitchiness in the extreme, I think wind speed and gusts would prove the greatest area of problems for one so small.:eek:

Peter R-B
Vfr

[Cornish Jack]

I note that the main concern has been dealt with ... the BROWN corduroys!!!:E:E

[outofwhack]

Tethering it will cause more problems than its solves.
I own and fly fullsize but have flown dozens of my own model helicopters in the early years when power/stability were big problems.

A good idea for first flights would be to simply increase the width of the undercarriage [sideways and for/aft] with lightweight beams to prevent rollover. pref with rollers at extremeties.

Good luck. Dont like the idea of belt drive to tail however. Never good on models. Shaft drive only way for power and reliability.

OOW

[toptobottom]

Onetrack

Rigga - From an engineering viewpoint, square sections have vastly increased strength over round sections, when it comes to load-carrying capacity.

Is that true? Most of the super structures built today use round tube over box section, including the new rooves over Wembley stadium and Wimbledon, as well as the 2012 Olympic stadium. I'm not an engineer, but if square section is stronger, why don't all helis have box setion tails :confused:

TTB

[John R81]

Comparing round and oblong beams, I though "total strength" (all directions) was unchanged but whereas round has equal resistance to any direction of distortion, oblong is stronger to specific direction but the penalty is reduced strength to others.

Not an engineer, stand to be enlightened

[bugdevheli]

Gentlemen, gentlemen, I really do appreciate all you comments, both positive and those of a more piss taking nature. I am old enough not to be plauged by the impertinance of those still wet behind the ears. Life is so short and must be lived to the full. I allways tell it as it really is. someone asked ," have previous bugs flown". Bug 1 hovered on its first trial (on tethers) Bug 2 was an attempt to utilise composites in the skid bow and body structures. Bug3 was built to encompass lessons learned during manufacture of MK1 and MK2. This machine now currently resides in Portugal and is currently being test hovered by its new owner. Bug4 was untill yesterday undergoing a rigorous ground test proceedure during which i managed to bugger the sprag clutch whilst doing start up proceedures. (sometimes all the calculations are disproved during actual use). Tomorrow, well, lets wait and see. (if we could still work in pounds and feet, and stuff we really understand, then life would be much easer). I mean who the bloody hell invented Newton Meters. Foot lbs. Twelve inches to the Foot. sounds logical to me "to be continued".

[bigglesbutler]

I have to agree with Gaseous's post, even a Super Puma or Sikorsky S61 just out of heavies sometimes isn't immediately airworthy. The idea of ground runs then working each control to check reaction is a good one.

Always think what's the worse that could happen and prepare for it at all stages, then when it doesn't happen you can laugh yourself all the way to the pub.

Si

[onetrack]

TTB - Nearly every design project is torn between strength and weight, from an engineers viewpoint. In many cases, weight saving is crucial, and round section often provides adequate strength - whereas the strength gain from box section is often badly offset by the weight gain. Cost also comes into the equation, with round section often considerably cheaper.

bugdevheli - I presume the sprag clutch engineering calculations didn't include adequate shock load factor? Nasty stuff, that shock loading. Did you know that a load suspended on a crane hook, if suddenly dropped 2", will almost double the load on the hook/cable/boom/jib? Yes, I must confess, I like the old feet, inches and ft lb stuff. I must be as old as you, I certainly have nearly the same amount of white hair ... :)

[VfrpilotPB/2]

Hey one track,

I have in my pocket 2 Florins, and 1 half crown, not many folk remember those, or know what value they are today!

Peter R-B:ok:
Vfr

[onetrack]

vfrpilotPB/2 - Ahhh, yes - florins and half crowns - but can you remember buying threepenny ice cream cones?? :D :)

[rans6andrew]

Entertaining thread, well done one and all. The spouting off by people who clearly don't know Bugdevheli, or "Julian" or the abilities of either is really amusing to the few on here that know both of them.

Go for it, Bugdevheli.

Andrew, a friend from years ago, from when the Mini 500 still showed promise.

[bugdevheli]

Andrew. Thank you. Its been a few years since we met. J is alive and well and married (just in case you did not know). He and she are both qualified and have their own aircraft Regards you know who.

[Gaseous]

Hey Andrew, It was me that mentioned Julian and there was no criticism implied. If its the same person, he's smart. He was developing a remote controlled tracking device to adjust the pitch links in flight and he once tracked my Enstrom with a chadwick. I only knew him through John Dunn and when John died I didn't see Julian again. His homebuilt flew brilliantly. People like him and Ben are to be applauded. :D:ok:

[seanbean]

Bug - outstanding! It's people like you that put the "Great" in Britain! I would love to see it in a low (safe!) hover. The very Best of British to you.

[rans6andrew]

Gaseous, I didn't think that you were being critical, I am just amused that people just...... Well you know what I mean.

Bugdevheli, I didn't know that J and Y had got hitched. I actually tried to visit him recently (3rd Sun in November) as I was in his neck of the woods. He had gone to see you for the weekend! I am up to date on his flying activities and their Wittman Tailwind. My heli licence is a bit lapsed now but I am still flying often. I have gone all "plank", I have two 3 axis microlights, one which I built from a kit, and we have just ordered another kit from the Ukraine. Must sell at least one aircraft to pay for the next one.

keep me posted, Andrew.

[toptobottom]

onetrack - understood re dilemma of balance 'twixt strength and weight of tube vs. box section - makes sense. As for threepenny ice cream cones, yes - i remember them rather too well, along with tanners and coppers :sad:

I also clearly remember making my very first purchase - a Mars bar, c. 1963 and costing the princely sum of 3d... Ah, those were the days, etc...

Bug - we're all dying to know what the next step in the plan is - if there is one :)

TTB

[ChopperFAN]

Has anyone tryed using a felxible drive for the rail rotors yet?

I have seen it many times on RC helicopters and never heard of any failures

A larger variant will make for a system with many less parts with high tail gearbox setups

Run the shaft through a bent sleve lined with nylon. As long as its correctly lubricated, I dont see why its not a good idea

Any thoughts?

Simon :ok:

[Tractor_Driver]

My first purchase was for a tanner.

I gave the lady a bob and she offered a pair of threepeny bits in exchange.

T_D

[blakmax]

OK I'll ask my obvious questions based on my usual themes: Are the blades bonded? If so by whom? Using what adhesive? After what surface preparation process? How were the bonds cured?

Same questions for the composite structure joints.

If the answers involve ACME and Wylie Cayote I'm outa here!

Regards

blakmax

[Cyclic Hotline]

Perhaps this product might offer the soution?

Bulls Balls®, Big Boy Nutz™, Original Truck Balls™, Truck Nuts, Truck Nutz, Bike Nutz & Bumper Nuts. (http://www.bullsballs.com/)

Not sure of the weight penalty!:eek:

[onetrack]

bugdevheli - Don't worry about risking your neck any more - I found the guy who'll volunteer for the TP job. He's the right size for your cute little machine, and suitably outfitted in the cojones dept, as well ...... :)

http://i48.tinypic.com/11qhf6r.jpg

[bugdevheli]

Onetrack, he is obviously a squirrel pilot. I have it on good authority that they are all endowed in a similar manner. Toptobottom. When i have proven the Bug airframe and drive systems, i plan to construct a full size ring rotor a mockup of which can be seen on one of the pics posted (the mock up sits on top os a pair of blades) The ring rotor is device that permits enormous inertia without the weight penalty of heavy blades. My belief is that until these VLH machines have loads of inertia they are risky at best, and deadly in low level operation, particularly the sort of flying carried out by low time pilots.BUG.

[cockney steve]

IMHO, there's a lot of cock talked about "aircraft quality", especially when it comes to GA and LAA /experimentals.

Often it comes down purely to the traceability (paper-trail)

Those "automotive quality" drive-belts (flat, multi-vee) are extremely durable,"fit and forget" items.
The longer, "serpentine" ones follow a convoluted path,sometimes with more than a 180* wrap round pulleys of~8-10cm diameter, driving water-pump, aircon-pump, power-steering pump,alternator and cooling-fan....all fluctuating loads at fluctuating speeds in an engine going ~900rpm to~ 7000 rpm. life-expectancy is often 100,000 miles +without failure or maintenance.

that tail -drive with balanced-loading on both sides of the boom (limited float needed to even-out inequalities between pairs) seems a simple, elegant,low-stress,low-maintenance tail-drive solution,

Model Helis using a similar toothed-belt to that employed in computer printers, are extremely reliable and the Raptor series,using that drive has been the most popular mass-produced kit for a fair while.

Glad to see someone with the courage of his own convictions not letting the nanny state suffocate him.

the jobsworths would not have allowed the Wrights to fly, nor the first hang-gliders.

Aviation at this level sems to have thrived on innovation outflanking the beaurocrats with their control and legislation.

Bravo!

[Northern flight]

Well all i can say is , if you have had the Balls along with the commitment and passion to build, design and engineer it then im sure you have the balls to fly it!!!
How wonderful that there is still someone out there with a true passion for design,engineering and flight, if it were not for people like you we would never have had the light bulb! the first tv! or indeed the first form of flight !!!!!!!
well done and keep up the good work anyone who cannot see the time and effort gone in to this machine and the commitment from yourself to it is obviously stupid.:D

[Graviman]

Bug,

A lot of carefull thought has gone into this machine. I'm guessing that you've done some testing on those skids to make sure they absorb energy for various scenarios. That rotorhead / swashplate looks like an engineering story in itself - one i'd be interested in hearing. Do you have any closeups of main rotor, tail rotor, control mech and rest of machine? Unless you are worried about disclosure of design etc. Looks like some interesting drivetrain around the (Triumph?) engine. Are those more belts hidden between those two aluminium plates?

The thing that astonishes me is that this was all designed by one person! Looks like many man-years of work. All you?

Just remember that every new engineering project is a collection of faults just waiting to be discovered. Take every opportunity to check that fatigue is not gently accumulating cycles (i know you've done FEA) and that wear is not gently rubbing away contact. Check every bolt torque as often as you can (vibration & joint movement) and look to see that those belts haven't picked up any FOD. Definately check welds very regularly - with die penetrant if practical.

BTW does the rotor / drivetrain have enough inertia without the ring-rotor for <2 seconds of flight with no power? Talking with the many (always extremely helpful) test pilots on Rotorheads i get the impression that the key is to carefully think out what the objective of the each flight is then figure out the absolute minimum risk way to achieve that objective. Sometimes that may involve sitting down for a cup of coffee.

Just my £0.005...

[VfrpilotPB/2]

This would work with a lightweight Turbine, in place of the Piston job! one of the Prune Rotorheads quite possibly has just the thing plus the knowledge! :ooh:

Peter R-B
Vfr

[bugdevheli]

Graviman and peter RB. Just a clarification! One of the photos posted shows the mk 3 machine which has a ring rotor device mounted above its normal pair of blades. This was done just to expose the ring rotor concept to interested parties at an airshow. The actual ring rotor will be fifteen feet diameter. The Ringrotor is something i have been working on, to provide great inertia with a minimum weight penalty. The Mk4 has been designed so as to be able to retro fit the ring rotor when airframe and drive systems are proven.This is why the tailboom lenght is adjustable. The current engine is a Yamaha FZR. I will post some closeups of bits you mention. Thanks Bug.

[Graviman]

Ah, it's a Yamaha FZR. Which size? I'm guessing you went with a 1000 but run it derated - not sure how many thousand miles of motorway speeds/power motorbike engines are designed to last these days. Helis seem to aim for a few thousand hours at least.

I like the concept: figure out the single main obstacle to making helicopters safe, rotor inertia, and then design a rotor specifically to improve this feature. And as a side benefit improve the aerodynamic efficiency by a potential maximum of 30% for a given rotor diameter. This one deserves to succeed!

Normally rotors are tested on top of whirl towers. Why not firmly bolt the whole helicopter to a balance, maybe out of ground effect, then "fly" it to check the performance? Or strap it to a weighted trolley (heavier version of your castored wheels on the skids) to keep it on terra-firma while you pull collective to what would be hover for a series of ground runs to get the feel of it? If you are sure where the C of G is then you could mount heli to trolley with four ball joint end links converging just above CG (for stability)*. Best if ball ends attatched to the fuselage, as close to C of G as possible. Use a scissor link (or drive shaft with sliding splines) to make trolley follow in yaw.

This would give you the feel of the machine in flight but without putting yourself at risk. In particular, confidence that the machine is behaving itself dynamically, including tail rotor and main rotor in flap-back. If you check all of the bolts, welds, belts, etc after each run you will prove to yourself that the machine is reliable.

Just a thought.


*I originally suggested tethers, but these would cause problems as they became taught. Also they do not allow various collective settings to be tried.

[southernweyr]

I completely agree with the advice given by Gaseous. Do not teather. If the main rotor and tail rotor react as expected while light on skids then hovering will not be a problem. Also, don't be afraid to slam that collective down if any rolling starts to occur. The landing gear won't mind. I have about 900 hours in Rotorways and what Gaseous posted is excactly what all the Rotorway pilots are instructed to do with their own helicopters. Also, the belt driven tail rotor was very reliable. I would not have any problems with the belts whatsoever for as you mentioned they last hundreds of thousands of miles and are even used on farm equipment with far more stress. Easy to inspect and replace, they are a great choice.

[slowrotor]

It might be easier to do some dynamic testing by bolting the machine on top of an old truck and racing up and down the runway or open field.
This has been done with fixed wings of odd design, such as canards, to test the limits.
Just an idea.

[bugdevheli]

Gentlemen. My invention that will help you keep it up that few seconds longer :)

http://i339.photobucket.com/albums/n474/bugdevelopments/1.jpg

[Gaseous]

Its up .. Its up..

Oh bugger. its going down now.:eek:

[toptobottom]

Bug - no offence, but that's a bit big for a steering wheel isn't it?

[slowrotor]

Is that a "tail" rotor?

[Northern flight]

What does it do?? please share, and i mean to Rotor not the beautiful girl !!

[Graviman]

Southernweyr, not trying to counter your thoughts here about avoiding tethers. My post was not very clear - i'll see if i can tidy it up. :)

What i meant to say is that the single main problem with tethers is that they apply loads to the airframe which do not pass through the C of G and thus produce a torque high enough to overpower any cyclic input. This will be even worse if the tether suddenly becomes taught as dynamic rolloever is sure to follow. I'm making the assumption here that BugDevHeli wants to find a way to accumulate time and test the machine with minimum risk to pilot. The best method is to have the machine fixed in such a way that the collective cannot alter the machines height, with the simplest being to bolt it to a trolley.

What i was trying to figure out is if there is a method of applying linkages between a mobile ground run trolley and airframe to simulate in flight loads and attitudes but keep machine in check in case of any problems. This would give Bug a feel for the machine as well as expose parts to realistic loads. If there was any problem the machine is still on the ground so there would be no complications.

The only practical way i can think to do this is to use 3 or 4 links all angled in to pass through C of G. This way collective and cyclic can be flown for realistic flight attitude, hence dynamics, hence loads with machine all the while being well supported. The problem though is that if the machine started to fall over (for whatever reason) then the links would now be pointing the wrong side of the C of G and would not stop the machine falling over. A simple solution is to have the virtual apex (where all links intersect) above the C of G, so that machine has to rotate some way before C of G passes outside of virtual pyramid created by linkages. An even safer solution would be to have a sprung centreing mechanism that would overcome any moment as the machine tried to fall over.

Bug, please comment whether any of this is any help. I'll try to clarify more if needed.

[bugdevheli]

Thanks for your suggestions. I had considered tethers, mechanical restraints of some kind, or possibly just going for getting skids light and then an inch or two clearance etc. Having had a previous machine do a 180 in the blink on an eye , i am considering short tethers for initial getting light on the skids and confirming tail rotor authority and then if all is well proceed to small hops foreward etc. The device the young lady is holding is a test model for my ring rotor. This enables me to acquire great inertia without the penalty of heavy blades or rotor hub. the outer ring constrains the inertial forces (depending on its elasticity) and also allows me to put the weight where i want it. It does however produce some unexpected flexation modes within the blades themselves. FDI analysis indicates an improvement in lift especially around the tips.The improved performance on the tip loss factor overcomes the additional drag of the ring itself Thanks Bug

[Graviman]

Bug,

Have you worked out the effective hinge offset with the ring rotor? I ran into headaches using standard Prouty equations. The easiest method is to compare rotating flapping frequency with rotational frequency then use:

Lead angle = 90 * (rpm/60) / frequency.

Rotating flapping frequency will be a standard output from your FEA (or test).

I'm sure this is old hat...

[bugdevheli]

Graviman. The answer is i have no idea as yet of what the optimum offset should be. Because we have a situation where each blade is influenced by the preceeding and following blades. All data to date has been acquired by (a) running a test rig where the rotor is ginbal mounted and has been free to teeter, or (b) FDA carried out by a university for me, where it was treeted as a simple rotating fan. I will eventually have to resort to my usual method which is make it, try it, if it does not work make it again. I have found that using this method the third attempt is usually somewhere near the mark. Thanks Bug.

[Skittles]

This may be a silly suggestion, but instead of worrying about tethering the thing, why not just give it some training wheels?

Make a nice light frame out of relatively thin but sturdy metal, and extend the landing gear by 10 feet in all directions. You are then assured that it cannot tip over unless you are greater than 10 feet from the ground. If anything goes wrong whilst in the hover you can cut the power and it will just sit back down.

Ovciously weight is an issue but if you planned it carefully I think it would be fine.

[Graviman]

Skittles,

Training wheels - not a bad idea. Will minimise risk of dynamic rollover. Actually looking at some fixed wing gear would help. Some tail-dragger main gear designed for operation on rough strips hinges so that tyre contact patch moves radially about C of G (ie high roll centre suspension). The benefit is that cross-wind landings do not risk rolling the aircraft on landing.

Designing skids to flex about C of G will give the same advantage. Bug seems to have already considered this. I like the curve in the struts too, since this allows compliance in direction of C of G too (as well as a little plastic strain energy absorbtion :ouch:).

----

Bug,

If teetering: the control lead angle will be 90 degrees (less delta3 for coning, wee-wa, and/or inflow roll). Actually, i would seriously consider Dave Jackson's unihub design to minimise shaft vibrations, hence fatigue alternating loads, for your ring rotor.

If hingeless: you only need to know the first in plane bending mode frequency of the full disk. If this was checked in FEA with centrifugal accel applied then you can find control lead angle directly from my formula above. If you only know in plane bending frequency when static then a reasonable first estimate may be found using:

Freq-rotating < SQRT( Freq-static^2 + (RPM/60)^2 )

Where Freq-rotating then gets put into the equation for lead angle.

This approach works just as well for a ring-rotor as for individual blades because any fully teetering disk would remain in plane as you move the axis, in just the same way that individual blades do.Thus you can add centrifugal accel and bending hinge moments.

Assuming this hasn't totally befuddled you, i'd be happy to clarify a little more...

[VfrpilotPB/2]

This is one of the most interesting threads on the Net, its giving many people time and room to think about many aspects that we are all involved with, not just in flying Helis but also in the engineering dept also, its the first thing I read when on the net!

Peter R-B
Vfr

[Aubrey.]

Same here, I'm thoroughly enjoying it. I'm a little glad I'm not going to be the one testing the machine, but very much looking forward to seeing this get airborne. This thread makes good reading and is inspiring too!

[bugdevheli]

Many thanks for you supportive and constructive comments. I should make it clear that i lay no claim to being a qualified pilot or for that matter particularly clever. Having to make your own helicopter stems from having a passion about something and not money to persue it in the normal manner' Regarding the machine, a new sprag clutch is on order and hopefully within the next week or so i will be attempting to get it off the ground. Looking at the Rotorway video i feel tethers are going to be my first choice. Having pulled it light on the skids already i know my brain was buzzing a bit, and i think i may not handle the full monty if anything happened that pushed me past my limits. Thank you. Bug

[Aubrey.]

Look forward to the next sitrep. Out of interest, are you a PPL holder? Where does the law stand on this type of prototype?

[bugdevheli]

Just found a few piccies. The one in tethered hover was Bug2. In answer to questions. No ppl, and in the UK i am informed you can test on tethers but you cant do what i am goin to do shortly:):)

http://i339.photobucket.com/albums/n474/bugdevelopments/tether.jpg
http://i339.photobucket.com/albums/n474/bugdevelopments/photo1.jpg
http://i339.photobucket.com/albums/n474/bugdevelopments/DSCF1344.jpg

[Graviman]

Bug,

Just make sure that when the tethers are taught they line up with the C of G.

The reason the rotorway went over is that skids do not allow any compliance (in comparison with oleos). So the skid touches and applies a force that does not pass through the C of G - this is called a torque and clearly overpowers any cyclic input. If you are lucky and dump the collective then the aircraft has not accumulated enough inertia about the longitudinal axis to roll over. Interesting to note that ship based helicopters allow negative pitch to apply a downwards force, which would help recover.

Allow as much compliance as you can in the tethers - bungee chord maybe. The more gently you deccelerate the airframe the lower the forces will be.

Ideally, tether the fuselage and not the skids to minimise effect of angular movement (ie CG moving off thether axis). Hard to achieve and be sure that tether does not foul the skids too (which could be a disaster). This may be why a lot of the pioneers used widely spaced oleos to allow tethers freedom of movement.

I still think you might be better off replacing skids with ball end links and do initial ground runs on a wide base trolley overweighted to overcome any lift the rotor could develope - including transition. Have links forming corners of a pyramid with apex just above CG. Diagonal crosses with bungee chord will overcome any tendancy to fallover. If not a scissor link under the fuselage then use a Watt Z-linkage on tail boom to stop any yaw without affecting pitch and roll. This will let you "fly" the machine to get a feel for its dynamics, albeit slowed down a little, as well as gain confidence in the design.

I'm pretty busy, but would be happy to talk off-line.
Still in Cambridgeshire but don't mind a day trip.

Mart

[bugdevheli]

First tethered test as promised, comments welcome...:ok:

HuLsyDTQMls

[bigglesbutler]

WOW congrats, that must have been a heart pumping ride. It has funny similarities to when I learnt to fly my model heli way back when. Another similarity that might cause problems is the vibration you notice in the left skid tube, that combined with the engine note REALLY reminds me of my model when the engine is running to lean and out of balance. The end effect on my model was parts breaking due to vibration, so please tune the engine nad check the balance on the output shaft. Not trying to scare monger just passing on my "similar" experience.

Well done though, I am mightily impressed :ok:

Si

[Graviman]

Bug,

I don't know how i missed this big event! :ouch:

Some of the TPs can comment way better, but i gather the best way is to feel the thing off the ground by cyclic forward with skids lifted at rear - that way collective finds it's position.

Congrats are in order!

[HeliChopter]

Bug,

1 - Top drawer, keep up the inventive's end! :D

2 - Was that a last minute crafty fag I saw being tossed out just as the beast sparked into life? That definitely completes the eccentric British engineer image! :)

[toptobottom]

Well done Bug - you're an inspiration! I would have worn a brown gaberdine raincoat and a flat cap to go with that Capstan!! :ok:

[mad_jock]

Brillant !!!!!!

Now stupid question from a plank driver/ex mech eng.

Is the fluttering on the tail boom shadows off the main rotar linked with the camera capture rate or is it a whore of a flap on the power belts to the back?

[bugdevheli]

Yes! it was a ciggy i desgarded just prior to lift off attempt.The cursed weed somehow consoles me just prior to a period of acute stress. The flutter you see is not a shadow, its a slack belt. I have now completed around five hours of tethered testing. the only failure so far has been a flexplate fracture bitween engine and drivechain.

[fly911]

Could be a sqwed observation, but could you be a slight bit aft on the CG? Seems like your heels want to lift off last. Keep up the great work! We need more pioneers like you!
Mikehttp://i135.photobucket.com/albums/q140/fly911/icon1fix.gif

[bugdevheli]

fly911, correct. A balance check showed that i needed about three pounds on the front at two feet in front of the mast. Have now fitted doors and its made things level again. Must have lost a few pounds myself during testing thanks bug

[GlennYoung]

Bugdevheli, its is great to see a homebuilt helicopter in the U.K that is not the Rotorway. I have looked at many USA, Italian, Candian home builds, which I must say do not look as clean and swept as your design. The new rotor design looks interesting, and its nice to see British engineering taking the first steps in driving progress.

Its a pitty that in the U.K to get this design flying without the need to teather is a pain, and the cost to get it passed would be a second mortgage, with no experimental category like in USA.

Unless it accidentlly slipped off those teathers :ok::}

[Nige321]

Old thread - I wonder if BugDevHeli got any futher... Anyone know...??

[JBL99]

Sadly, G-INFO says G-BXTV was de-registered on 25/3/2014.

[Nige321]

Mmmmm...About the time he bought a Mini500...


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