Quaich SSDR

[SGIAN DUBH]

Just getting ready to commence the Quaich Flight Testing ( Collection of the Microlight is imminent, once our Trailer is emptied of the Building Supplies for the Holiday Home projects ).

 

The Quaich has a Rotax 447 engine & has an empty weight of 184.2kg & will be cleared to 300kg under the UK SSDR acceptance.

 

We are limiting the Pilot weight to 86kg to allow for 30litres of fuel to be carried ( the tank will be replaced by a 40ltr Tank as calcs will allow 40ltrs with a 86kg Pilot )

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[bexrbetter]

Bludbewdymaaatehey.

 

 

[Head in the clouds]

A couple of observations that you might want to consider during your testing -

 

1. If it was mine the elevator and rudder would have much more area. The area they have at the moment is more typical of an aircraft with a stall speed in the vicinity of 60kt than the 35-40kt I imagine this will have. Consequently it's very likely that the elevator will run out of authority a fair while before it could bring the mainplane to the critical angle and stall it, so you may find your landings will be a good bit faster than anticipated, or is desirable.

 

Similarly the elevator may not have sufficient authority to lift the tail during the take-off roll. If the aircraft has flaps and you use them on take-off then they would move the centre of pressure of the mainplane aft and that would help with the situation very considerably. If you don't have flaps, or don't use them for take-off, and if the engine has sufficient power to overcome the drag and reach take-off speed in the three-point attitude (with a 447 it should have) then you would be likely to become airborne in the almost-stalled attitude. Once the wheels are off then you'd want to lower the nose and build speed rather promptly or risk a wing-drop (lowering the nose would happen 'automatically' if you maintain stick forward as it lifts off, of course, though that's not entirely intuitive) ... this situation of perhaps not being able to lift the tail prior to take-off is made worse by the position of the mainwheels which appears to be a little forward of the leading edge (in level flight attitude) - right below the leading edge is more 'usual'. The condition would be improved by ensuring a CG toward the forward end of the range but that could be a bad trade-off in terms of increasing the landing speed even further because of running out of 'up' elevator authority even earlier.

 

2. It has a tall rudder, and some of its area below the HS, which is very good, but I'd venture to say that you might find it has rather limited capability in cross-winds. The large amount of fuselage side-area behind the CG, the forward landing gear position and the smallish (narrow chord/high aspect ratio which stalls at a lower Reynolds number than a lower aspect ratio would) rudder all combine to limit the aircraft's cross-wind ability, so I'd be leading up to cross-wind landings gradually.

 

 

[SGIAN DUBH]

A couple of observations that you might want to consider during your testing -1. If it was mine the elevator and rudder would have much more area. The area they have at the moment is more typical of an aircraft with a stall speed in the vicinity of 60kt than the 35-40kt I imagine this will have. Consequently it's very likely that the elevator will run out of authority a fair while before it could bring the mainplane to the critical angle and stall it, so you may find your landings will be a good bit faster than anticipated, or is desirable.

H.I.T.C, Do you have credentials that back up your opinions or are they just ' well-meaning ' findings? I only ask because I seem to be getting different opinions from here to there ;-) Until it gets test-flown ( in the air ) it will be an unknown stall speed though I am almost certain it will be in the 30kt area ( I certainly hope so because it needs to be to comply with SSDR ) I am assured the Elevator has more than enough authority to ensure a controlled landing.

 

Similarly the elevator may not have sufficient authority to lift the tail during the take-off roll. If the aircraft has flaps and you use them on take-off then they would move the centre of pressure of the mainplane aft and that would help with the situation very considerably. If you don't have flaps, or don't use them for take-off, and if the engine has sufficient power to overcome the drag and reach take-off speed in the three-point attitude (with a 447 it should have) then you would be likely to become airborne in the almost-stalled attitude. Once the wheels are off then you'd want to lower the nose and build speed rather promptly or risk a wing-drop (lowering the nose would happen 'automatically' if you maintain stick forward as it lifts off, of course, though that's not entirely intuitive) ... this situation of perhaps not being able to lift the tail prior to take-off is made worse by the position of the mainwheels which appears to be a little forward of the leading edge (in level flight attitude) - right below the leading edge is more 'usual'. The condition would be improved by ensuring a CG toward the forward end of the range but that could be a bad trade-off in terms of increasing the landing speed even further because of running out of 'up' elevator authority even earlier.

I am assured the Elevator has more than enough authority to ensure a controlled tail lift in the take off run. I have very little confidence in 2 strokes but as a 447 /503 is the only realistic option for this aircraft I am stuck with that as a powerplant....... I have ample hours on Taildraggers so I don't envisage that I will have any problem getting the tail up ( I doubt my Test Pilot will have any problems either ). I am intrigued by the mainwheels reference.... I have flown many Tailwaggers with mainwheels ahead of the Leading Edge & they are more tricky but not dangerously tricky. I will be looking closely at the CofG & if it can be moved toward the front of the range it will be adjusted.

 

2. It has a tall rudder, and some of its area below the HS, which is very good, but I'd venture to say that you might find it has rather limited capability in cross-winds. The large amount of fuselage side-area behind the CG, the forward landing gear position and the smallish (narrow chord/high aspect ratio which stalls at a lower Reynolds number than a lower aspect ratio would) rudder all combine to limit the aircraft's cross-wind ability, so I'd be leading up to cross-wind landings gradually.

Again the Crosswind capability will be explored closely before we set a figure that we are happy with..... One of the beauties of our UK SSDR Category is that " it is a licence to explore the parameters of your aircraft "

 

The UK CAA have even said " SSDR allows Aerobatics if your Design is capable of withstanding the G forces associated with Aeros "

 

I won't personally do Aeros in any SSDR that I currently operate, might be tempted in a Phantom Ultralight if we manage to acquire one ;-)

 

Currently having a bit of grief getting a Kolb Twinstar through SSDR because it is ex LAA/PFA & it looks like the LAA are reluctant now to have too many LAA aircraft moving onto the SSDR category.

 

 

[Head in the clouds]

H.I.T.C, Do you have credentials that back up your opinions or are they just ' well-meaning ' findings? I only ask because I seem to be getting different opinions from here to there ;-) Until it gets test-flown ( in the air ) it will be an unknown stall speed though I am almost certain it will be in the 30kt area ( I certainly hope so because it needs to be to comply with SSDR ) I am assured the Elevator has more than enough authority to ensure a controlled landing.

It depends what you call credentials, I don't have formal aeronautical engineering qualifications however I have been studying the subject since 1976 during which time I have completed fifteen aircraft, not completed two others and am nearing the completion of the current one (DooMaw, my avatar). The completed ones were all successful and fly well, the varying experiences I had with 'tuning' some of the earlier ones, and abandoning two of them are all testament to the learning curve. All are/were of my own design. Experience of that kind, and over four decades, does provide valuable real-world experience that some might say amount to a little more than 'well meaning findings', but by all means take my observations as you see fit and do with them as you will ... :-)

 

I didn't say the Quaich's stall speed would be much above the 30-40kt region, I said the tail control surfaces looked like you might have a minimum controllable speed well above the stall speed. I said the elevator wasn't likely to have enough authority to bring the mainplane to the stall. That results in the minimum controllable speed being well above the stall speed because when you reach full rear stick travel the lift and moment provided by the elevator isn't sufficient to overcome the moments provided by the CG being ahead of the Centre of Pressure (CP), the pitching moment of the airfoil and any additional pitching moment provided by extending flaps. It all adds up to a plane that won't fly as slow as it could, if you could bring it to the stall.

 

It's a much misunderstood thing, people bring the stick back to the stop, the plane gets slower until eventually it reaches a minimum flying speed and 'mushes'. How often have you heard people say their plane is very kindly in the stall, it just mushes? Fact is, it hasn't reached the stall at all. Now, that doesn't mean the assurance you were given that "the Elevator has more than enough authority to ensure a controlled landing" is wrong, it means that the landing will need to be much faster than you expect, because if my assessment of the elevator's size is correct, then you'll run out of elevator authority way above the stall speed.

 

And - earlier, in the Sgian Dubh thread, you said you had an aerodynamicist who was "the most respected aircraft engineer in UK" or words very close to that, involved in this program. Above you said "Until it gets test-flown ( in the air ) it will be an unknown stall speed". That is a mystery ... how can you have such a highly revered person on the team and he doesn't seem to know how to do the most basic of aeronautical calcs i.e. the stall speed prediction. Presumably you know the airfoil section, the wing area and the weight of the aircraft? That, and a set of polars for the section (available on many sites online) are all you need to predict the stall speed with great accuracy. Determination of similar for the HS, factored by the tail moment, would tell you for certain whether the elevator will have the authority to fully stall the mainplane or not ... it's basic stuff.

 

I am assured the Elevator has more than enough authority to ensure a controlled tail lift in the take off run. I have very little confidence in 2 strokes but as a 447 /503 is the only realistic option for this aircraft I am stuck with that as a powerplant....... I have ample hours on Taildraggers so I don't envisage that I will have any problem getting the tail up ( I doubt my Test Pilot will have any problems either ). I am intrigued by the mainwheels reference.... I have flown many Tailwaggers with mainwheels ahead of the Leading Edge & they are more tricky but not dangerously tricky. I will be looking closely at the CofG & if it can be moved toward the front of the range it will be adjusted.

Assurances are good - but the proof will be in the pudding, as they say, and the actual fact will be very easy to find out as soon as you start taxi tests, so the tail-lift thing is a non-issue - you'll know the answer before you ever need to get airborne. If the one providing the assurances has conducted a lift coefficient and moment calc for the HS and VS then it would be useful to attach it here, if you like. Second opinions would likely be forthcoming and where controllability and test-flying is concerned it doesn't hurt to have a few of them.

 

Just my opinion again - but a well maintained 2T with a knowledgeable operator can be very reliable. In my experiences the key issues are - maintain full throttle in the climb, a lot of folks like to 'back off a little' and that leans the mixture considerably which makes it run a lot hotter and risks nipping up. Make sure you don't have air leaks in the induction, either at the rubber mounts after the carbies or direct to the crankcase (via the fuel-pump pulse line is a classic), they both lean the mixture with disastrous results. Avoid low idle speeds on the ground, the 'rattle' breaks the crankshafts. Avoid long low throttle descents, it shock-cools them and that can crack things, or they can oil up the plugs and stop, or oil-injected ones can run with insufficient oil in the mix. Use 2T oil for air-cooled 2T engines, not for water-cooled engines like outboard engines, the oil is designed to burn at different temperatures i.e. air-cooled engines run hotter so oil for water-cooled engines burns too soon if used in air-cooled engines. HIH.

 

I didn't say the forward position of the mainwheels was 'dangerously tricky', and neither did I mean that it need be any kind of problem. What I was on about was that it would have two effects - first it would make the weight on the tailwheel greater than if those wheels were further aft, consequently the 'down' elevator has more work to do to lift the tail in the take-off run, and secondly the further the wheels are ahead of the CG, the more work the rudder has to do in a crosswind. In both cases the forward wheels position does a dis-service to the already very marginal tail flying surfaces' effectiveness.

 

 

[SGIAN DUBH]

It depends what you call credentials, I don't have formal aeronautical engineering qualifications however I have been studying the subject since 1976 during which time I have completed fifteen aircraft, not completed two others and am nearing the completion of the current one (DooMaw, my avatar). The completed ones were all successful and fly well, the varying experiences I had with 'tuning' some of the earlier ones, and abandoning two of them are all testament to the learning curve. All are/were of my own design. Experience of that kind, and over four decades, does provide valuable real-world experience that some might say amount to a little more than 'well meaning findings', but by all means take my observations as you see fit and do with them as you will ... :-) .

I always take what others say or suggest as Good Sound Advice offered with the best intentions, the problem in the UK is " Everyone is an Aircraft Engineer until the engine starts " Thus why I look further afield for advice and analyse whether the person is a Waffler or an informed font of knowledge, I am sure you are the latter "

 

I didn't say the Quaich's stall speed would be much above the 30-40kt region, I said the tail control surfaces looked like you might have a minimum controllable speed well above the stall speed. I said the elevator wasn't likely to have enough authority to bring the mainplane to the stall. That results in the minimum controllable speed being well above the stall speed because when you reach full rear stick travel the lift and moment provided by the elevator isn't sufficient to overcome the moments provided by the CG being ahead of the Centre of Pressure (CP), the pitching moment of the airfoil and any additional pitching moment provided by extending flaps. It all adds up to a plane that won't fly as slow as it could, if you could bring it to the stall..

I take your points & will bank them for future recall during testing......you may well be right in what you foresee, I hope you are wrong but you are certainly putting reasoned doubt into my mind.

 

It's a much misunderstood thing, people bring the stick back to the stop, the plane gets slower until eventually it reaches a minimum flying speed and 'mushes'. How often have you heard people say their plane is very kindly in the stall, it just mushes? Fact is, it hasn't reached the stall at all. Now, that doesn't mean the assurance you were given that "the Elevator has more than enough authority to ensure a controlled landing" is wrong, it means that the landing will need to be much faster than you expect, because if my assessment of the elevator's size is correct, then you'll run out of elevator authority way above the stall speed..

The Stall will be fully explored, I won't be settling for Mushing... I want to see a FULL STALL ( It will be done at Altitude for safety )

 

And - earlier, in the Sgian Dubh thread, you said you had an aerodynamicist who was "the most respected aircraft engineer in UK" or words very close to that, involved in this program. Above you said "Until it gets test-flown ( in the air ) it will be an unknown stall speed". That is a mystery ... how can you have such a highly revered person on the team and he doesn't seem to know how to do the most basic of aeronautical calcs i.e. the stall speed prediction. Presumably you know the airfoil section, the wing area and the weight of the aircraft? That, and a set of polars for the section (available on many sites online) are all you need to predict the stall speed with great accuracy. Determination of similar for the HS, factored by the tail moment, would tell you for certain whether the elevator will have the authority to fully stall the mainplane or not ... it's basic stuff..

My Aerodynamicist will be doing the calcs ( to see how they differ from the designers scribbles ) He is currently wrapped up in the Sgian Dubh & I don't fill his pockets with enough dollars to have him looking at more than 1 project at the same time. ( He would look at figures if I asked him, so when I have both the aeroplane & all the spreadsheets in front of me I will be in a better place to ask him questions ) The Vto is supposed to be 37.4mph ( 32.52kts) So I am hoping that a Touchdown at 30kts is feasible....... The Cruise is supposed to be 70mph (61kias) to 105mph (91kias ) with a VNE of 110mph

 

Assurances are good - but the proof will be in the pudding, as they say, and the actual fact will be very easy to find out as soon as you start taxi tests, so the tail-lift thing is a non-issue - you'll know the answer before you ever need to get airborne. If the one providing the assurances has conducted a lift coefficient and moment calc for the HS and VS then it would be useful to attach it here, if you like. Second opinions would likely be forthcoming and where controllability and test-flying is concerned it doesn't hurt to have a few of them..

The builder/designer has reams of calcs on file that I will pay full attention to when I need to commence testing.

 

Just my opinion again - but a well maintained 2T with a knowledgeable operator can be very reliable. In my experiences the key issues are - maintain full throttle in the climb, a lot of folks like to 'back off a little' and that leans the mixture considerably which makes it run a lot hotter and risks nipping up. Make sure you don't have air leaks in the induction, either at the rubber mounts after the carbies or direct to the crankcase (via the fuel-pump pulse line is a classic), they both lean the mixture with disastrous results. Avoid low idle speeds on the ground, the 'rattle' breaks the crankshafts. Avoid long low throttle descents, it shock-cools them and that can crack things, or they can oil up the plugs and stop, or oil-injected ones can run with insufficient oil in the mix. Use 2T oil for air-cooled 2T engines, not for water-cooled engines like outboard engines, the oil is designed to burn at different temperatures i.e. air-cooled engines run hotter so oil for water-cooled engines burns too soon if used in air-cooled engines. HIH..

We are both singing from the same hymnsheet on the 2 STROKE Operations, I am not a 'back off a little' in the climb pilot......... I am going to have a Rotax specialist look at the 447 BEFORE I even start it up.

 

I didn't say the forward position of the mainwheels was 'dangerously tricky', and neither did I mean that it need be any kind of problem. What I was on about was that it would have two effects - first it would make the weight on the tailwheel greater than if those wheels were further aft, consequently the 'down' elevator has more work to do to lift the tail in the take-off run, and secondly the further the wheels are ahead of the CG, the more work the rudder has to do in a crosswind. In both cases the forward wheels position does a dis-service to the already very marginal tail flying surfaces' effectiveness.

I will be wary of what you have said because I am used to 200-300hp Engined Tailwaggers so I always have had bags of power on tap to lift the tail & aerobatic surfaces that are substantial.

Thank you for your input ;-)

 

 

[rotax618]

Very interesting little aircraft, could you please post some photos of the construction method/materials. Are structural limitations or regulations limiting the MTOW?

 

 

[SGIAN DUBH]

Very interesting little aircraft, could you please post some photos of the construction method/materials. Are structural limitations or regulations limiting the MTOW?

Regulations limit the MTOW to 300kg on the basis that it is an UNCERTIFIED build that has never previously been registered as a Single Seat Aircraft in the UK.

 

INTRODUCTION

 

In 2007, the CAA responded to industry requests to reduce the regulatory burden on very light

 

aircraft. This resulted in single-seat microlights of low weight and wing loading being

 

‘deregulated’ from an airworthiness point of view: a group of aircraft known as ‘sub-115’.

 

In 2013, the CAA proposed to increase the scope of this category to include all single-seat

 

microlights. In May 2014, CAA issued an exemption allowing any single-seat microlight to be

 

‘deregulated’, if the owner applied to do so, with the intention of incorporating this change into

 

the Air Navigation Order (ANO) in 2015 at which point all single seat microlights will become

 

deregulated by default.

 

A single seat microlight (SSDR) is defined as an aircraft which:

 

a) Is designed to carry one person;

 

b) Has a maximum take-off mass of no more than:

 

i. 300 kg for a single seat landplane (or 390 kg for a single seat landplane of which

 

51% was built by an amateur, or non-profit making association of amateurs, for

 

their own purposes and without any commercial objective, in respect of which a

 

Permit to Fly issued by the CAA was in force prior to 1 January 2003*); or

 

ii. 315 kg for a single seat landplane equipped with an airframe mounted total

 

recovering parachute system; or

 

iii. 330 kg for a single seat amphibian or floatplane; and

 

c) Has a stall speed or minimum steady flight speed in the landing configuration not

 

exceeding 35 knots calibrated airspeed.

 

* The intent is that if this clause is used to allow a microlight of between 300/315/330 kg and

 

390 kg max gross weight to be an SSDR, the Permit to Fly that was in force prior to 1.1.03

 

must have been for the aircraft as a single seat microlight not as a two seat microlight or as an

 

SEP Aeroplane, i.e. to ‘grandfather’ pre-existing ‘heavy’ single seat microlights into the SSDR

 

category.

 

SUB-115

 

Since 30th April 2007 it has been legal to fly a lightweight ‘sub-115 kg’ single-seat microlight

 

aeroplane without a permit to fly or any of the associated official design investigation, formal

 

flight testing, maintenance schedules, annual inspections or permit paperwork.

 

The ANO definition of this group of aircraft is:

 

A microlight aeroplane which:

 

i. Is designed to carry one person only;

 

ii. Has a maximum weight without its pilot and fuel of 115 kg;

 

iii. Has a maximum wing loading without its pilot and fuel of 10 kg per square meter;

 

and

 

iv. Is flying on a private flight.

 

These aircraft are no longer eligible to hold a Permit to Fly and Certificates of Validity (“Permit

 

renewals”) may not be issued.

 

HEAVIER AIRCRAFT

 

The May 2014 exemption and other information are set out in CAA Information Notice IN-

 

2014/101. Owners of single-seat microlights that don’t fall into the ‘sub-115’ category may

 

apply to the CAA to take advantage of the exemption by completing the form attached to the

 

Information Notice and sending to the CAA. The exemption only applies to private flights and

 

therefore does not include commercial flights or ‘aerial work’. Again, this only exempts aircraft

 

from the requirement to hold a Permit to Fly (and associated design and manufacture

 

approval, permit revalidations, formal annual inspections, etc).

 

TL 2.17 Operating Deregulated Microlights Page 1 of 7

 

OPERATING DEREGULATED

 

MICROLIGHTS

 

TL 2.17

 

ISSUE 4

 

JULY 2014

 

The definition of single-seat microlight that aircraft must comply with is as listed in the

 

introduction section above.

 

At the current time, owners of aircraft that meet this definition may apply for the exemption,

 

which is optional. From 2015, the CAA currently intends to incorporate this into law, at which

 

point it will no longer be optional and all aircraft meeting the definition will be deregulated. If

 

you object to this position, we recommend that you write to the CAA’s General Aviation Unit

 

with your objection (we would also appreciate a copy of your correspondence at the LAA).

 

If an aircraft is presently cleared as an SEP ‘Group A’ aircraft then it is probably not eligible to

 

be a microlight and hence not eligible to be deregulated, even if the gross weight falls within

 

the limits above. Airspeed indicators frequently under-read by several knots at low speeds,

 

giving the impression that the stall speed is lower than it actually is. Transferring an existing

 

‘group A’ LAA aircraft to the microlight category in order to become classified as a deregulated

 

aircraft will involve first getting a change in classification agreed by LAA Engineering, which is

 

put in train by submitting a category change mod application (form MOD10).

 

For the guidance of members who own single-seat ‘Group A’ aircraft, from the LAA’s

 

knowledge, the following aircraft are unlikely to be eligible for deregulation because they

 

exceed the 35 knot calibrated stall speed and/or the weight requirement:

 

• Tipsy Nipper

 

• Clutton Fred

 

• Brugger Colibri MB2

 

• Druine Turbulent

 

• Luton Minor

 

• Jodel D9/D92

 

• Taylor Monoplane

 

• QAC Quickie

 

• Colomban MC-15 Cri-Cri

 

• Corby Starlet

 

• Monnett Moni

 

• Wolf WII Boredom Fighter

 

• Whittaker MW7

 

• Star-Lite SL-1

 

• Rans S9

 

• Staaken Flitzer

 

• Chiltern DW.1/1A

 

For the guidance of members thinking of designing their own SSDR, or looking to buy or build

 

an existing design to operate in this category, the table below provides guidance on the

 

minimum wing area likely to be needed to meet the 35 knot calibrated stall speed

 

requirement, for different max gross weights and wing/flap configurations.

 

The table is based on the results of many true stall speed tests carried out over the years on

 

microlights. Naturally the stall speed is affected by many things as well as the wing loading,

 

configuration, elevator authority, cg position, wing section, aspect ratio and twist to name but

 

a few, but the table below is intended to show a reasonable typical value of minimum wingarea needed to stall at 35 knots true airspeed or less, as a starting point for design or aguideline in assessing whether an existing design might fit the category.TL 2.17 Operating Deregulated Microlights Page 2 of 7

 

DEFINITIONS‘ Aeroplane’ means an aircraft supported in flight by fixed wings (as opposed to rotating wings)and therefore includes conventional rigid wings, flex wings and powered parachutes, withwheels or foot-launched, and controlled by any method including control surfaces or weightshift or a mixture of the two. It does not include gyroplanes or helicopters. It can be poweredby any form of motor including reciprocating, rotary, jet, rocket, electric, steam, etc, althoughit would need to comply with the noise regulations for microlights (see above).‘Empty weight’ is the weight of the aircraft without pilot or fuel, and need not include itemscarried at the discretion of the pilot on a flight-by-flight basis e.g. hand-held radios, extra seatcushions, etc.

 

‘Maximum gross weight’ is the maximum weight of the aircraft including fuel, pilot and allother items carried.‘Empty wing loading’ is the empty weight in kilograms (see above) divided by the wing area insquare metres. For a conventional aircraft, the lifting area is taken as the area of the wings,including wing flaps (if fitted) and ailerons. Where the wing panels attach to the fuselage sides,it is normal to include the ‘virtual’ portion of wing buried in the fuselage. So with a typicalparallel-chord wing with square tips, the wing area becomes simply the wing span multipliedby wing chord. If the wing is tapered, multiply the wing span by the mean chord to get thewing area. The mean chord is the chord measured at one quarter of the wing span outboardfrom the aircraft centreline. In the case of a canard aeroplane it is acceptable to include thecanard area with the wing area. With a biplane, add the areas of the upper and lower wings,upper wing centre section and the ‘virtual’ centre section linking the two lower wings.‘Registered with the CAA’ means you must apply to the CAA Registrations Department for aunique G-???? registration, using a form CA1 which you can download from the CAA’s website.There is a registration fee to be paid, but this is a one-off fee.‘Display of G-???? registration letters’ means that the registration must be clearly displayedunder the port wing, on both sides of the fuselage sides or fin, and indelibly marked on anengraved fireproof metal plate attached to the fuselage. The details of the required sizes of theletters, letter style, colouring, and orientation of the lettering on the surfaces are provided inthe CAA booklet CAP 523 which can be downloaded from the CAA website. You will be sentone of these automatically when your G-???? registration letters are allocated.‘Single seater’ means the aircraft may only carry one person. This is not as obvious as itsounds, as some microlights do not have seats as such – the pilot of a foot-launched flex-wingfor example commonly flies in the prone position supported by a bag.‘Stall speed’ is the minimum flying speed in the landing configuration, as marked by a ‘classic’nose drop or by the pitch control reaching its backstop. The stall is approached at adeceleration of approximately 1 knot/second. For the purposes of establishing whether anaircraft is a microlight, the calibrated stall speed must be no more than 35 knots. A tool isavailable on the website to help establish calibrated ASI data (Aircraft & Technical – Flighttesting aircraft).

 

A FEW WORDS OF WARNING Just because there are very few formal requirements surrounding this new breed ofderegulated microlight, it does not mean they are toys. Like any aircraft, they will kill or injureyou given half a chance, especially so as most will offer very little by way of pilot protection ina crash. The deregulated microlight has been freed from the burden of airworthiness regulationnot because they are inherently safe for the pilot, but only because they have been judged tocause a negligible risk to third parties. As with any other deregulated hazardous sport such asmountaineering and ocean racing, the responsibility for your safety will lie entirely in your ownhands. There is nothing in the new rules to stop you making your wing spars from knotty pine,just as there’s nothing to stop you making a rowing boat from blotting-paper – and each willhave a similar chance of success. The fact that there is no legal requirement for designevaluation, maintenance or flight testing does not mean that none of these are required: itmeans that it is entirely up to the owner to decide on his or her own approach to theseactivities. Based on what happens in other countries where there are similar deregulated forms of aviation, the best safety net is for the owners to be part of a group of like-minded people with the benefit of one or two experienced souls able to act as mentors, giving guidance to those who may be moving unwittingly into particularly dangerous territory. If youare thinking of building your own deregulated microlight then joining your local LAA Strut would be a good first step, and the local LAA inspectors will be able to give advice although for

 

deregulated aircraft, for liability reasons, they will always have to qualify their advice with astatement that their advice is their own opinion only, and that it is entirely up to theowner/pilot to research the situation and form his own opinion before deciding what to do.The LAA inspector has no formal responsibility towards a deregulated microlight owner but willnevertheless probably be only too happy to give you the benefit of his advice and experience.

 

WHAT’S THAT OLD THING HANGING UP IN THE BACK OF THE HANGAR? A word of caution about resurrecting old single-seat microlights from the early 1980s era whichmight fall into the SSDR category, many of which can be found hung up in the roof of hangers,festooned in cobwebs, or even ‘slung out back’ in a heap of aluminium tubing and flappingDacron, having been long-grounded after the introduction of the dreaded ‘Section S’ in 1984.Before thinking of getting one of these prehistoric microlights airborne again, look verycarefully. Was the design a safe one? Much has been learnt about microlight safety since thosedays, and things like elevator control cables made of nylon cord have long ago passed fromfavour – many people died in the early days of microlighting proving that some of the featuresof these old designs were unsatisfactory. And has the aircraft been properly looked afterduring its life? Probably not, as its value will have sunk to nothing for many years and it willmost likely have been left to corrode away in peace, out of sight and out of mind. The fabric isalmost certainly ruined by exposure to ultra-violet light, and will rip to shreds in your handswith way below the original strength. Airframe tubing might look serviceable – but how do youknow if it is the original bit? In the early days, when tubing got bent in mishaps it was notuncommon to substitute material from other crashed machines, or whatever was lying around– like electrical conduit for example, even though its strength might be way down on what isneeded for the job. To fly any aircraft with suspect materials in the primary structure is likeplaying Russian Roulette.

 

DESIGNING YOUR OWN? If you are thinking of coming up with your own design in the deregulated category, as long asyou are a LAA member we will be happy to give general advice and guidance from LAA HQ, butas with our inspectors, will caution you that this is our opinion only and that it is entirely up toyou to research matters and make your own decision. We can point you in the direction of themany aircraft design books available from LAA bookshop, such as Hiscocks ‘Design of LightAircraft’, and standard works of reference like Stinton’s ‘Design of the Aeroplane’. The LAAwebsite is also a ready source of help and in particular, see Technical Leaflet TL 1.15 ‘examplemicrolight aircraft loading calculations’ which leads you step by step through how to work outthe loads on the aircraft prior to stress analysis when sizing the structural components, orsand bag testing your completed airframe.We would recommend you design the airframe to cope with all the main load cases of BCARSection S even though this is not mandatory in this deregulated class. Appendix A and B ofCS-VLA also provide a very helpful simplified approach to working out aircraft loads, which isespecially useful for the deregulated microlight designer without too much previous aircraftdesign experience.

 

MODIFYING AN EXISTING DESIGN Several designs of single-seat microlight in the USA appear to fall within the SSDR category.Be careful on three counts – firstly, are they really as light as claimed, and secondly, do theyhave enough wing area, and thirdly, are they safe? You may find that you have to pare everybit of extra weight out of the aircraft to get it to squeak into the 115 kg limit - one LAA’errecently found he had to fit a lighter, much less powerful engine for example – there seems tobe very little checking of such things in other countries, so don’t take any weight figures frommanufacturers as gospel truth – weigh it yourself and see! If you find that the design is shortof wing area at the finalised empty weight, be particularly wary of suggestions that the wing

 

"> area can easily be increased by adding a little extra wing span or chord, or a little of both.This would fall into the category of a serious change needing proper engineering investigation.An extra foot or two of span on each wing can drastically increase the stresses in the wingspars, struts and carry-through structures, not to mention increasing tail loads and fuselageloads - and so it goes on. Increasing the wing chord may similarly alter the distribution of loadbetween the spars or cause serious stability problems. Carrying out such changes on an ad hocbasis will be fraught with danger.

 

CONCLUSION Not since the early 1980s has there been the freedom to design and build simple microlights inthe UK without needing a permit to fly. Back then, a number of fatal accidents causedquestions to be asked in Parliament and legislation to be hurried into place to close theloophole. Now, thirty years later, the microlight industry has matured, microlight pilot trainingand licensing are closely controlled and so there is a reasonable chance that history will notrepeat itself and this time we can be left to get on the building and flying these very simple,lightweight aircraft without the need for official interference. It is up to all those participatingto observe the highest safety standards, avoid an upsurge in the accident rate and so preserveand nurture this new found freedom to build and fly.The LAA continues to support members who own single seat microlights, whether deregulatedor remaining on a Permit. Our Engineering team has wealth of knowledge on these aircraft,generically and on each specific type, and advice is there for the asking. We are stillconsidering how we might offer more practical services and how they might be funded, but wewant the aircraft which our members fly to be safe, whether deregulated or not, and considerthat the LAA’s well-proven safety culture, advice and information-sharing service are the bestmeans to promote this.

 

DATA copied from LAA Guidance notes.

 

 

[SGIAN DUBH]

Here are the Construction Pics so far ;-)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[pylon500]

Just some observations, which I'm not 100% sure of..?

 

Is the wing actually tapered?

 

Depending on which photo's I look at, I get the impression that the wing has a lot of cantilever after the strut attach point?

 

Yet the spar caps look to be about the same size over the whole length?

 

The strut reinforcement blocks look a bit 'sudden', meaning they don't appear to taper the load out into the web gradually.

 

I think I would have used a plywood rib at the strut attach, to stabilise the shear movement in the top cap in that area.

 

At least with full span ailerons, the twisting load on the wing is lessoned.

 

Separately, I would have mounted the engine a little higher, for multiple reasons;

 

Less power/pitching moment,

 

Better ground clearance,

 

More room under the mount to try to hide the exhaust, (it can be done, you don't need that big can hanging totally on the outside).

 

How wide is your cockpit?, does look a little cramped..

 

Sorry for any grief, just my observations (hopefully all wrong).

 

 

[kasper]

I'll pop in 2p worth ... the construction pics are I think possibly a mix of the Sgian Dubh (quite tapered wing outer panels ) and the Quaich (gently tapered wing over its length)

 

Both built by Hugh and use the same basic construction method. And for the Quaich the spars are as per the pics - 1 inch caps top n bottom with a 4mm cut slot for the single spar web.

 

Might be wrong on the mix of photos and I'm sure Pete can correct but from what I recall speaking to Hugh years ago when the loan engines were being cobbled together to display them the Quaich was not as tapered.

 

 

[SGIAN DUBH]

Just some observations, which I'm not 100% sure of..?Is the wing actually tapered?

Yes the Wing is Tapered.

Depending on which photo's I look at, I get the impression that the wing has a lot of cantilever after the strut attach point?Yet the spar caps look to be about the same size over the whole length?

The strut reinforcement blocks look a bit 'sudden', meaning they don't appear to taper the load out into the web gradually.

 

I think I would have used a plywood rib at the strut attach, to stabilise the shear movement in the top cap in that area.

Yes, there is quite a lot of wing area outwith the Strut attachment.

 

At least with full span ailerons, the twisting load on the wing is lessoned.Separately, I would have mounted the engine a little higher, for multiple reasons;

Less power/pitching moment,

 

Better ground clearance,

 

More room under the mount to try to hide the exhaust, (it can be done, you don't need that big can hanging totally on the outside).

Hopefully the full span ailerons will give a balanced roll rate without stressing the wing.

The engine is set to be on a precise thrustline.

 

The Ground clearance is ample before the prop tip would get near the ground ( the tail would be very high in a propstrike scenario ).

 

The Exhaust is going to be inside the cowling as per attached picture ;-)

 

How wide is your cockpit?, does look a little cramped..

The Cockpit is very narrow @ 23in (58.5cm) Lets just say " it is SNUG for me " ;-)

 

Sorry for any grief, just my observations (hopefully all wrong).

I am more than happy to read constructive comments or questions, so feel free to post anything on the subject.... I am not capricious in any way ( some may disagree on that ) & I would rather 'bat' back answers than get to a point after the event where someone says " I thought that was wrong, but didn't want to say as it might offend "

I have a ' Can Do ' attitude to most things in life, it is sometimes good to have outside intervention to rein me in a little.

 

 

 

 

 

[SGIAN DUBH]

I'll pop in 2p worth ... the construction pics are I think possibly a mix of the Sgian Dubh (quite tapered wing outer panels ) and the Quaich (gently tapered wing over its length)

The Photos are all from the Quaich Construction Folder ( as seen in Quaich Gallery ) so I am assuming they are all Quaich related.

 

Both built by Hugh and use the same basic construction method. And for the Quaich the spars are as per the pics - 1 inch caps top n bottom with a 4mm cut slot for the single spar web.

Hugh seems to have used the same construction method in both the Sgian Dubh & Quaich, I have every faith in his construction techniques ( just as well seeing as I will be putting Human 'Guinea Pigs' into them for Flight Testing ) I am certainly going to do some 'Taxying Tests' that may include a 20m hop ( if I can shoehorn myself into a 23in wide seat, it should be possible albeit snug ), the actual flight testing will be undertaken by a sub 86kg Pilot.

 

Might be wrong on the mix of photos and I'm sure Pete can correct but from what I recall speaking to Hugh years ago when the loan engines were being cobbled together to display them the Quaich was not as tapered.

The Wing Taper can be seen in the attachment in the previous post, the engine in the Quaich is a Rotax 447 which I am guessing is of Unknown provenance, so I will be having it closely scrutinized before any Air gets under the wheels. The Sgian Dubh is now being fitted with a Rotax 503 of Known provenance.

I would like to see The Quaich & Sgian Dubh flying together as that is something that is assured of putting a huge smile on Hughies face ;-)

 

The Quaich & Sgian Dubh are getting incredible support from the UK CAA as they now seem to be very pro-active, sadly the BMAA are being very negative towards these projects, luckily the CAA are the decision makers & they are 100% happy with the concept of both these projects.

 

Understandably the CAA are not so pro-active in accepting the Iolaire onto the SSDR Category, they are prepared to accept it if I can categorically declare it is below 204kg empty but they would prefer me to be able to tell them it is 184kg empty ( which I think is a Tall order ).

 

I am thinking about putting the Iolaire through 'E' Conditions as it has already flown but was never granted a UK Permit to Fly under the BMAA/CAA process.

 

 

[rotax618]

Very pretty little aeroplane. Am interested to know what the skin is over the foam and how you get such a smooth surface finish.

 

 

[SGIAN DUBH]

Very pretty little aeroplane. Am interested to know what the skin is over the foam and how you get such a smooth surface finish.

the Quaich is constructed from extruded polystyrene foam with 290t glass cloth and West System epoxy. All awkward contours, leading edge D's etc. were hot wired.

To further highlight some of the questions/remarks made in previous posts I hope the following will answer a few queries

 

Utilising the same type of construction as in the Iolaire and Sgian Dubh the Quaich is a well tried and popular layout. The aircraft is designed to be easy to handle in the air as well as on the ground. The use of a tail wheel (via the rudder pedals, operating the standard ‘push right go right’ system) combined with fairly large diameter main wheels ensures good performance into and out of short grass strips. If the take off weight is around 290kg and with a best glide ratio in the region of 12:1 then the Vto (take off velocity) will be 38.4mph and Vs (stall velocity) will be 33.2mph. These are calculated figures based on the above moderate assumptions and will improve if take off weight is lower.

 

The high aspect ratio wing is braced at the aerodynamic centre on the 25% chord line by a single strut to the mainspar, which is straight. The full span ailerons are differentialed 1:1.5 and have a rearward pivot point giving a Frise effect when deployed upwards. These devices help to alleviate adverse yaw. The tips of all flying surfaces have been fitted with anti vortex leading edges and tip plates to improve drag at these points.

 

Good all-round visibility is achieved by the low cowling and the sloping fuselage sides. Access is via the lowered port side lifting door/window. The contoured seat forms part of the structure of the main fuselage former.

 

The type of construction employed requires no specialist skills or machinery and could be carried out by the average handyman. The rigid flying surface obtained by all composite methods ensures a better aerodynamic package and therefore better all round performance. The wings are detachable for easy transportation. Assembly and disassembly time will be around 10 minutes.

 

 

[IBob]

Hm, it's a tricky one, that "average handyman":

 

My father was a furniture maker and hide upholsterer who worked mainly by eye (as they did). He regarded himself as a competent tradesman, would have been embarrassed by the label 'craftsman' we would stick on him today. He was an average handyman of his time.

 

And if you go back in Boy's Own annuals, they had designs for DIY diving helmets, while over at Popular Mechanics, the average handyman was being assured that he could make a violin in t' back shed, no trouble.

 

But I think we can say things have slipped a bit since then, at least in what we call first world countries. I myself live in a land where, despite a stirling reputation for innovation and a willingness to modify just about anything, fully two thirds of adult males should never be allowed anywhere near a Black and Decker. Fortunately they don't seem tempted to build aeroplanes...or diving helmets...or violins...

 

 

[kasper]

However some parts of modern day fixing upper stuff is helped by technology ... Youtube videos on various parts of the housebuilding have been refreshingly helpful to me in going back over things I have not done for 25 years

 

 

[IBob]

However some parts of modern day fixing upper stuff is helped by technology ... Youtube videos on various parts of the housebuilding have been refreshingly helpful to me in going back over things I have not done for 25 years

Your right. And tools and materials and methods continue to evolve and improve, some quite dramatically.

 

Now, where was that small child? I'm almost ready to lower him into the North Sea....

 

 

[rotax618]

Could you share your method of producing such a smooth surface, do you cover the cured layup with micros and block sand the surface (very time consuming) or do you have a trick that makes the construction a bit easier?

 

 

[pylon500]

The aircraft is reminiscent of a plane I test flew many years back, that was also built by an above average 'handy man', built his own house, wooden boat, half finished a KR-2 but got sick of dealing with DoT (CASA back then) and also builds wooden weaving looms.

 

As a University lecturer, he clued himself up on engineering and aerodynamics, and designed and built his own ultralight.

 

 

Only powered by a Rotax 503, it could still cruise in the 80kt range.

 

Was also a bit squeezy in the cabin, and was all plywood.

 

My own designed single seater was all metal, also a 503, was 30" wide in the cabin (nicknamed the flying armchair), and could hit the mid 70's.

 

 

I could also fit a full size, two stroke exhaust within the cowl.

 

Was later converted to a two seater.

 

Haas been sitting the back of my hangar for a few years, but nearly ready to fly again...

 

 

Still not sure how you're getting that exhaust in there?

 

Arthur.

 

 

[rotax618]

I would like to use your construction method on a project of my design, have you had a chance to proof load the wings to verify your calculations?

 

The only concern I have is the disconnection of the wingskin with the spar, relying on the shear between the foam and spar flanges, I discounted this method because of this concern, my solution was to shape the foam to the top of the spar caps and form the glass wing skins using the Strojnik method (lay up the skin on a flat mylar sheet and before it is cured ,hang the mylar up by two edges forming an aerofoil shape) then vacuum the skin sections onto the foam and spar caps.

 

Do you think this method would produce a stronger wing with less finishing?

 

 

[Deskpilot]

Rotax, I agree with your concern re wing skin and spar separation. I asked Hugh about it and he wasn't concerned but I change his design when I was thinking of building one. I lowered the the rib surfaces by 10mm and had the foam sheets level with the spar rather than over it. This allowed the skin to be adhered directly to the spar.

 

 

 

 

[SGIAN DUBH]

The Quaich was put on the Back Burner as the Sgian Dubh was making Little Progress, now I think the Sgian Dubh is getting very close to being ready for testing, so the Quaich will be getting registered soon ( waiting for a 2017 registered date ).

 

That I think will fly very soon as it is 99% complete already ( just needs a few instruments fitted )

 

 

[Deskpilot]

Eagerly awaiting flight test for both aircraft. Don't give up now.

 

 

[SGIAN DUBH]

Eagerly awaiting flight test for both aircraft. Don't give up now.

The Sgian Dubh is getting ever closer to being ready for flight ;-) I am sure it will be a Momentus Day when both fly over Hugh's Home ;-)