Category Archives: Tiger Cub

The Tiger Cub story

Back to the beginning: Project Tiger Cub Story part 13b

Thinking about legs

After cleaning and checking the undercarriage legs I notice a difference between the later ones that came with Kit SU208 and the ones supplied with GMJSU (Kit SO175).

While both are fitted with the nylon anti crush insert at the top the earlier legs are single tube at the lower end the later ones are doubled by having another tube inside for the area though which the plates that form the attachment to the axle. Sure enough there is a small damaged area to the lower ends of the earlier legs. I am a bit puzzled by this until I notice that the end of the doubled units are not cut straight as are the older ones but are eased to prevent contact with the axle itself. While they don’t actually touch in either case they are very close on the straight cut tubes. So it would seem that under landing loads it is possible for them to come in contact in the older model. As the legs are angled up to the attachment point this would place them in bending rather than as designed having the load though the two bolts that are in shear and from them straight up the tubes to the main front fuselage framing. It’s bit like a detective story piecing together the development although sometimes it feels almost a form of witchcraft. Well it seem like it at times as I shuffle my Tarot cards (the accumulation of service bulletins and circulars) and cast the Runes of assorted bits a pieces in the workshop the whole thing woven though with the myths and legends from the elder days of microlighting. It is satisfying though as the bits fall into place, SP starts to take the shape of an aeroplane again and end of the rainbow gets a little closer.

Removing the side plates and cleaning up the bits involves removing a peculiar gunk from the undercarriage legs for SU. Strange stuff that has left a golden translucent film over the alloy that while it is not unattractive has to come off so that I can crack test all the bits.

After cleaning I check all the bolt holes and discover that one of the undercarriage legs and one side plate from kit 208 have the holes elongated. Red labels for those and red penitrant dye for the others. As ever it is very satisfying when the developer shows a pristine white surface.

Moving on the main undercarriage axle I clean to the accumulated grime of years to find the wheel bearing surfaces in surprisingly good nick. My luck seemed in as all the holes were still round and the right size then I struck trouble, the darn thing wasn’t straight. Blast it, I laid it on a flat surface and measured, it was certainly not straight, but then I remembered reading somewhere that there was an allowable amount of deflection, trouble was I couldn’t remember where I’d read it or how much was considered acceptable. So, I read again the Kit Build Instructions, nothing there then though the Service bulletins and news circulars, zilch before finding it in the Maintenance Manual. Maximum allowed deflection 1”, that’s right, 25mm; deflexion on my axle? 1.5mm, phew! I sat down and poured myself a glass of wine, it felt as if I deserved it.

Back to the beginning: Project Tiger Cub Story part 13

Rivets (and the power of the Internet)

So I order up the rivets, job done, we e ell not quite. Ben is now concerned about riveting in general and asks me to let him know in what other positions I have to replace them. Books and drawings spread all over the table I set to finding out wherever else they may lurk Luckily out of the ones that I turn up only one other place that worries Ben. This is the mounting plates for the interplane struts, he tells me that the stress on these is very complex. After a think I see what he means, not only the flying and landing loads transmitted though the rigging wires there are the torsional loads from the changing lift distribution in manoeuvring and at differing speeds and also the loads caused by control deflections. Complicated stuff and way beyond my aging brain cells so it is good for my moral that Ben has to consult Billy Brooks who is just about the most experienced microlight engineer in the country. Between them they come up with an answer. That is that neither are happy to use monal rivets in that position and the recommendation is that I use Avdel Monobolts, a sort of super pop rivet. I trace a source and order some up, how did we manage before the Internet?

Ordering up both rivet types I find that they have more that Bens approval in common, minimum orders for both of a 100 rivets. Oh well I’ll not run out for a while, it also makes me appreciate the brilliant service that I have become used to from LAS.

I write these recommendations into my repair scheme as modifications and send off the latest version. Result! At last the draft MAAN comes back, which will allow me to go ahead. As far as approvals go I feel that I am on the downhill run with just some answers to find about the last missing service bulletins. I put out an appeal on the BMAA forums and the Tiger Cub Yahoo group for these but without much hope. I get two replies but neither is able to help. So I’m back on my own resources again and I start to wade though all the associated paperwork that I have accumulated. This is fascinating stuff, it’s like taking a trip back to the early exciting days of microlighting. I find that I have a very nicely produced sale brochure complete with picture of a Cub flying, undergoing load tests and loads of enthusiastic blurb.

All these pictures are of the first Cub that is now proudly displayed in Newark Air Museum, where the curator was so helpful to me when I started this project so many years ago.

Quote from Test Pilots Report

“Take off, however was a different story. No gentle transition from ground to air with this ship. Full throttle gives a very rapid acceleration with a swing to the left needing firm pressure on the rudder to keep straight. The tail comes up almost before the aircraft has moved and in approximate 20 to 25yds we were airborne and I had to quickly raise the nose to hold the speed back to 40 knots IAS. A glance at the ASI confirmed an initial climb rate of 1000 feet per minute which settles down to 800 feet per minute once clear of ground effect.” Sounds good to me

There are price lists from your local friendly microlight dealer including ballistic parachute systems, I didn’t know that they went back that far. Local flying club newsletters that talk of long past meetings and flyins, many of these seeming just to be held in a farmers field. Also in the collection are newsletters from MBA and Tiger Cub Developments giving warnings that you need to be a taildragger pilot to handle a Cub and introducing a coaching scheme to train pilots. These newsletters also track the introduction of airworthiness requirements for microlights and MBAs struggle to gain approval as the flow of new customers dried up awaiting the outcome. Then as Type Acceptance was gained the company was broke and the banner passed to Tiger Cub Developments.

For me though, the important thing was that I believe from the contents of the newsletters I can prove the content of the missing service bulletins.

Once again out with the spanners! I have a front floor to fit with my nice shiny stainless steel rivets and despite my concerns about using a hand puller on 4.8mm stainless fixings they went in well with a generous dollop of Zinc Chromate. Then an afternoon spent with my collection of bracing wires got to the top of my list. These were just tied into bundles according to the aircraft that they came from and had to be sorted into their various functions. I had wires from GMJSP, GMJSU, GMNKM and Kit 208 but none of them singly forming a complete set. I laid them all out on the lawns at the back of the house and started checking them by length and the fittings still attached to them. After hours of patient detective work I was confidant that I knew where they all belonged and labelled them all with their function and origin. Phew I was glad that was over with. Although I have no intention of using the old wires I need them for patterns when the new ones are made up.

Then out of the blue I get an e-mail from South Africa, a chap called Christian has just purchased a Tiger Cub but is short of information, can I help? His Cub is an interesting little beast with sprung undercarriage and a centre section fuel tank. It has suffered a landing accident but looks in fairly good shape. By UK standards he has had an epic trip to collect it and he has a history of kit building so it seems that little aircraft is in good hands.

Thanks to my assiduous gathering of Tiger Cub paperwork I can supply the handbooks, kit build instructions and most of the Service Bulletins. Loaded on a disc. It is a pleasant feeling to know that all those miles away another little Cub is on its way back where it belongs, in the air.

Just after that disc is launched I hear from Paul who has just obtained one Tiger Cub G-MMIH and almost enough of another one to restore it so we exchange information.

Paul can supply me with some of my missing service bulletins and I have some stuff that is useful to him, result!

After having read some of the (until now) mysterious missing bulletins I find that one that had caused me some concern MS SB 020. Mandatory. In the Type Acceptance Data Sheets in simply states “Rear Fuselage Bulkhead” with no further detail. A bit worrying that as that bulkhead is the anchor point for the rear ends of the longerons the rear tube of the fin from which the rudder is hinged and the tailwheel. Although I have a bulkhead that has done much flying attached to GMNKM it looked exactly to same to me as the ones from GMJSU and GMMKT. Had they all been modified? A bit difficult to be certain, was I missing something? I checked and measured everything, plate thickness, hole sizes the lot, identical! Not really reassured but unable to think of anything else I re-read all the circulars to see if there was a clue, nothing. Then Paul e-mailed me a copy and all was revealed, due to heavy tailfirst touchdowns some lower longeron brackets had been found cracked. The requirement was to check condition before flight, literally lift the tail and look, I’d never have guessed that. So no modification needed just a check, thanks Paul. Copies added to the information disc and sent on to Christian and a new disc to be made for Ben and one niggling worry out of the way.

Back to the workshop first to dismantle the main undercarriage from SU and to check the same bits from Kit 208, as usual taking photos and labelling all the bits.

Then with this done and ready for cleaning I can treat myself to some thing that I have been looking forward to, re-uniting the front and rear sections of fuselage. After much tweaking, fiddling and a bit of cursing the fuselage stood as a single unit for the first time since. 1986.

Back to the beginning: Project Tiger Cub Story part 12

Some work in the cockpit

Following Ben’s visit I set to finishing the front section of the fuselage. The front end I’d left pinned together with old bolts and I had done no riveting until Ben had seen my newly fabricated front tubes. So I completed riveting up the new throttle quadrant so that the throttle support tube could be fitted. I offered it up to strike a problem, it didn’t fit. Humm, it had fitted before when back in the mists of time I had dismantled it. Then I got it, despite the trouble that I’d taken with labelling everything up I’d fitted the starboard upright to the port side and visa versa, Idiot. Ohh well, stupid but curable with care. By cunning use of the triangulation of the structure I was able to remove both main uprights replacing such bolts as held other tubes in place in the right order so that I could swap the offending tubes over while maintaining the structure. Those in place, the right place this time, the throttle support tube slid neatly into place. Then working my way methodically though the assembly I replaced the old bolts with new ones painted with Zinc Chromate and wound on the new nylocs. 

I really could now feel that I was starting on the fun bits and get started at installing the controls. First off, the rudder pedals, I fitted them to the brackets that I re-installed on the cockpit floor after crack testing. They moved smoothly on their pivot and the end float was exactly as specified in the build instructions,

 I was starting to get a good feeling about this. Next, install the front cockpit floor, no room for error here, as this is structural giving triangulation to the front of the cockpit. I slid it into position and clamped it up only to find that I had pinched the monel rivets that I had bought hold it into place for another job. A bit of a pain, but not a disaster nothing that a call to LAS wouldn’t sort out. So clamping it into place I moved on to the rudder pulley in the rear of the cockpit section. No sign of wear to the pulley bearings so after a bit of a clean up the pulleys spun as merrily as new. Fitted with nice new bolts I slotted them into place and another little job was sorted. The next thing to re-fit was part of one of Jim Romains mods. It was just as well that I had taken pictures of the bits before dismantling. For this one Jim had changed the non-differential cable driven aileron circuit for a rod controlled system that provided some differential to the control.

For this one Jim had changed the non-differential cable driven aileron circuit for a rod controlled system that provided some differential to the control. To achieve this he had fitted a sleeve with two offset arms around the outer tube control column. Attached to these control rods ran to bell cranks that were mounted on an additional tube fitted athwartships.

These provided the differential and another rod each side ran to the bell cranks which are detachable to allow wing folding, these fit to the ends of the aileron control tubes. As I am missing one of the control rods I’ll have to get one made to the original spec. As I have been cleared by Ben to get this done at an aviation workshop to only real problem will be the cost. As the second tubes will be easy to fit later as long as the cockpit sides are left open I can still press on.

The hiccup with the rivets for the floor proves to be to my advantage as Ben is unhappy with the use of monel rivets in that position. He had gone away a worked out the rivet loading, because it was right behind the front bulkhead it was subject to considerable side force from propeller torque and a good deal of vibration. According to the “Big White Book” the FAA standards for inspection and repair, pop rivets should not be used in places where they are subject to vibration unless the rivet walls, without the central mandrill, are up to taking the load. It seems that monel rivets are not, all was not lost though as Ben found some stainless rivets that met all the requirements of the “Big White Book” and the bit in the CAAs own ‘Section S’ that covers side loads on engines.

Back to the beginning: Project Tiger Cub Story part 11b

and a surprise visitation

Then out of the blue a phone call from Ben in the BMAA tech office, he would like to come to see me and discuss the project so we agree a date. I hang up, well press the red button on my mobile but the term “hang up” conjures the wonderful vision of the old Victorian phones. Anyway I digress, but the idea of carting one of those around in my pocket amuses me.  Then I begin to wonder what I’ve done wrong, am I going to be manacled and hauled to Gatwick to explain myself? I can think of nothing, so with a feeling of unaccustomed virtue I begin to look forward to the visit.

On the appointed morning I answer the summons of the bell and open the door to find Ben complete with briefcase and camera bag. Over coffee we go though the mod status in fair detail, Ben has written them up in a little table to simplify the mass of Service Bulletins, some from MBA (Micro Biplane Aviation), some from TCD (Tiger Cub Developments) and of course the Romain modifications themselves. As I’d already noticed some later SBs supersede earlier ones and some Romain ones replace or supersede others. It is a bit of a tangled web, but with all the documentation spread over the dining table we unravel it until it makes sense and we agree the final mod status for GMJSP.

Then it is time to view the beast in its lair (the workshop). As it is the first Cub that Ben has seen he is surprised at how small it is, just as I was when I first saw one back in the early eighties. After a good look over to see just how it is put together he focuses in on the replacement parts that I have made and the parts that I propose to have made.

Firstly the made components, the replacement throttle quadrant that I have made to the drawings in the SB that requires the change from original and then the new “A” tubes. These are the ones described in episode 7 and my new ones are made from 6061 T6 alloy. Ben does a quick “back of fag packet” sketch and calculation and seems happy with what I’ve done but he will do a full stress analysis back at the office. I describe my workshop procedures, separation and labelling of parts as well as the checks carried out.

 We then retire back to the dining room table and some more coffee to discuss the parts that I intend to have made, the missing control rod and a new set of rigging wires. He seems happy that I intend to have both of these professionally made within the aviation industry and we go though the Aircraft Spruce Catalogue to make sure that the rod end bearings that I need are still available. Firing up the computer we sort though my workbook to locate the sources of components to be used in the final build. After making some notes we head back to the lair, or should that be den I really don’t know what is appropriate for Tigers, for Ben to take some photos.

Finally Ben tells me that he is generally happy with my repair scheme and will sort out an appropriate inspection regime and send it though to me, Result!

After another coffee we head to the farm to view the Cub that is in one piece KT.

Another coffee later Ben struggles into the cockpit and like everybody else is amazed just how much room there is in there, when you are in, a veritable Tardis of an aeroplane. As he remarked it is all very eighties.

So all in all an extremely successful day and I await the documentation plopping though my letter box. I enjoyed meeting Ben and it certainly gave the lie to all the rubbish that has been spouted about the denizens of the tech office. Ben is an enthusiastic microlighter who flies both flexies and three axis aircraft. He has both a Quik and is rebuilding an MW5 and his enthusiasm for microlighting glows around him like an aura.

Of course after such a good day I could be a little biased.

Back to the beginning: Project Tiger Cub Story part 11a

Progress at last, fitting the fuel tank

With the tray made and ready to fit I glued in the runners for the construction to sit on I was now ready for the next stage. Cutting strips of thin birch ply I fixed those with epoxy resin to the leading edges of the foam that form the front of the rear fuselage section. This was then re-enforced with glass fibre tape all as detailed in the tank lowering mod.

As soon as I had fitted an outlet pipe to the drip tray it was all ready to start to come together.

Sliding the tank into place and fixing it with the ever ready epoxy resin I started to make the polythene curtains to line the sides and rear of the foam. This was a weird shape but the third one fitted and epoxy and tape soon had it fitted in place.

The next thing was to get the tank fitted to the front fuselage section and the first piece of that is the rail that holds the shoulder straps of the seat harness. I have several sets of harness so I check them all over, going over the stitching carefully. I am happy that the best set of all is the one that came from SP. Being stored all those years seems to have helped and the webbing and stitches are in good shape with a small amount of rust on the face of the buckle showing as the only blemish.

The top support for the tank bolts to the shoulder harness rail with the webbing that holds the tank between the two alloy sections. This webbing is also in very good shape and I have no hesitation in fitting it and the nicely cleaned tank is hauled into place. With the lower support fitted we are almost ready to unite the fuselage sections. There is a short delay as I have borrowed a “T” piece intended for the fuel drain to use on the other little project, that of tidying up an AX3 for Saxon Microlights and like a clot I’ve not replaced it straight away.

In the meantime I revert to the preparation of the paperwork and spend some time copying the Tiger Cub maintenance manual and the Pilot and operators handbook to disc where they join the Build Manual that I had already sorted. I’ll send copies of this to the Tech office with the Service Bulletins; I’m amazed that they don’t already have this stuff. I cannot see how they have supported the type all these years without, as they seem to have almost no information at all and Tiger Cubs have been around for better than 25 years.

In the midst of this we visited the SPLASH aviation show at the NEC, I must be strange because I enjoyed it, but to hear the whingers after the show it must have been awful. Maybe I went somewhere else? We seemed to meet so many people that we barely got all around the show where I at least found plenty of interest. It was particularly good to see the resurgent interest in single seaters and to see all the younger faces of the hanglider and footlaunch crowds, as wise old Deepak (sorry Deepak, wise but not so old) said, “they are the future microlighters”. One of the special meetings was with the guys running Grass Strip Aviation, the importers of the Fokker Eindekker replica. They turned out to be some of the fellow Tiger Cub restorers that I have been corresponding with for the last couple of years. As a result of this I was able to send one of them a disc containing all my Tiger Cub information. If this helps more of the little beasts back in the air that would be a result as my latest copy of the MF reveals the sad news that none are presently in permit.

That stiffened my resolve and I returned to my spanners once again. Things start to come together the drip tray is completed and has its polythene curtains fitted.

Turning my attention to the front fuselage section I bolt the tank rails up firmly, hang on the tank and the two fuselage sections are ready to unite.

Back to the beginning: Project Tiger Cub Story part 10

Paper, paper! and a little bit of wood

Meantime on the SP front, the work carried out had been mostly paperwork. There had been a time that I had thought the old saying that “ No aircraft shall fly until its Maximum All Up Weight is equalled by the weight of its paperwork” was an exaggeration.

Not so, it seems if anything to be an understatement as I wade slowly though the textbooks and masses of web information to answer the points raised by the Tec Office the heap of paperwork!information and references steadily grows. The trouble with such searches is the time it takes. I can spend a couple of hours with the spanners in my workshop and achieve a fair amount, but 2hours of internet search or 2hours spent going though reference books and the end results are very small.

So recent events modified the intended work on SP in a couple of areas. The first one concerned the seat belts, with KT for the first time I was able to sit in a complete Tiger Cub cockpit, well, complete if you could ignore the instrument panel resting on your knees. The seat belt situation was far better than I’d have believed possible, mostly due to the fact that the seat was suspended on its own harness and so sat differently with somebody in it. Not having to alter that would save masses of work and potential hassle from the lads in the Tec Office. The other decision was to mount the fuel tank to comply with the mandatory mod on standard Tiger Cubs rather than stick with the Romain version for which I had no paperwork. I could foresee problems ahead if I stuck with the Romain mod that had pre dated the standard mod, but on the other hand I had the paperwork for the later mod and I had two examples of how it should be. So it would seem to be better to go with the flow.

For the sake of what little remains of my sanity I needed to take a break for the computer and books and with a feeling of great relief I took up my spanners again. I returned to the workshop and SP. Having made the decision to go with the standard tank mod rather than the Romain one putting that in place had to be the next job.

First I had to remove the front cockpit section that I had temporarily fitted for photos to show the Romain Mods of the side glazing of the cockpit and the bottom hung door. Interestingly the Tiger Cub as originally made had just a gap and no door was fitted then people started doing their own thing. Jim Romain had designed his bottom hung door; others had hung them from the side tubes. This in fact had been the cause of a fatal accident when a door opening to the rear had swung open on climb out and the aircraft had gone out of control. After that any doors fitted opened towards the front, as was the case with KT.

Anyway, photos taken and the front section had to be removed again to gain good access and the top of the blue foam that formed the top of the fuselage had to be cut back. Jim had fitted his inside the fuselage but the mod showed the tank top level with top of the foam so I had to comply with that. Next job was to make up the drip tray. That shouldn’t be too much of a problem as I had the drawings plus two complete ones to work from. The tray itself was made from thin birch plywood and coated with epoxy resin. Well that shouldn’t present any problems, resin I have and thin birch ply is available at any decent model shop.

It proved a bit fiddly getting everything to fit as the whole thing was mounted at a strange angle designed to tip any large spillage of fuel clear of the blue foam. Not a bad thing that though as petrol melts away the foam, and the idea of flying an aeroplane with its fuselage gradually dissolving is not attractive to say the least.

I worked away steadily with a very sharp knife making the peculiar angles that were needed to get a good fit. It was quite engrossing work and took for longer than I had anticipated.

Then, all the pieces lay complete on my bench and I made a crude jig to hold all the parts while they were glued together. Finally fixed into one piece I offered it up to the rear fuselage, success, it fitted just fine.

Drip tray in place Then I had to fit the forward bulkhead as specified in the mod, but as this was simply made from blue foam it was soon done. A trial fit of the tank, just to be sure there are no lurking snags then I will ready to fit the tray assembly. Then after resin painting the tray and fitting the polythene skirts to protect the fuselage sides and the rear bulkhead and I will be close to re-uniting both sections of the fuselage. That will be a great day.

Back to the beginning: Project Tiger Cub Story part 9

A surprise gift and a little bit of history

Then out of the blue I get an offer that I can’t refuse, a complete Tiger Cub and trailer hangar FREE. All that and no trek to the frozen North this time, this one is at Eltham less than a hour away. I arrange to go for a look with Joan one evening. It’s dark by the time we arrive but it easy to spot which house, it’s the one with the large scruffy trailer on the drive. We knock on the door and are answered by a short figure with bright intelligent eyes that sparkle at us though he glasses. Hello, he says, I’d hoped that you get here before dark. It’s there he says pointing at the trailer, I don’t know what you are to be able to see, I had hoped that you be here before dark he reiterated. I’m Ken he says shaking hands as we introduce ourselves. We got our little torch from the car and peered into the trailer to reveal a totally complete little Cub her registration GMMKT shining on her tail. She has two flat tyres and some of the fabric seams are peeling, that apart she looks in good shape considering that she has sat in her trailer for better than 20 yrs. Retiring inside we learn a lot more. Ken, it seems is a retired engineer who worked much of the time for the MOD,. he then worked offshore. He still has a JAR PPL which he uses to fly the occasional Cessna.

Ken told us that KT was built by him at the end of unregulated microlighting so there were no build inspections. To gain her permit he sent her to the MBA factory for test flying. While she was there awaiting flight the factory went under. So he brought her home again, then he started his offshore work and so missed the time where Russ Light formed Tiger Cub Developments to support the little biplanes that he liked so much. Russ then moved on to the two seat version, the lovely Sherwood Ranger and poor old KT had missed her chance. A call to the BMAA confirmed there was little or no chance of KT ever getting a permit. As Cubs were a jig built kit though it seemed that she could be used as a source of spare parts in the rebuild of another Cub, KM for instance. So I guess at least most of her would eventually get to fly.

OK, next problem, how to get her home and where was that home to be? Both were solved easier than I’d have believed. Firstly, at Joan’s suggestion I rang Tony HS, Hon. Sec. of the Essex Microlight Club. Tony volunteered straight away and he was perfectly suited to the task. As an enthusiastic caravan owner he had a car that was well matched to the job and had a huge amount of experience at towing large loads. Finding a home for her turned into a simple task, in three days I’d had two offers. Firstly from Rob at London Colney where by removing the wings I’d be able to store her in the back of Robs hangar and the trailer in the trailer park and secondly an offer from Angie to store her at the farm. It really is amazing how helpful people can be.

The big pickup day arrived, or at least the pickup evening. I met up with Tony at the M25 services. It wasn’t until I got there that I remembered that I’d never seen Tony’s car, his aeroplane yes, car no. Still I suppose that is one of the few blessings of the mobile phone. As it happened Tony arrived within minutes of me so  we transferred all the bits and pieces that I thought that we might need and set off. This time we arrived in daylight and Tony had a good look inside before we set to covering the whole thing with new tarpaulins. This was because the old ones although still keeping the weather out looked pretty rotten and my imagination had us shedding bits of rotting canvas all over the M25 and the Kent and Essex countryside as we trailed disintegrating flags of cloth like the Black Pearl from the Pirates of the Caribbean. Tony checked out the running gear and we were away. We moved smoothly along with Tony showing his expertise and making it all look very easy. All went well until Tony heard that the M11 was blocked so we headed in from South Weald, neither of us knew this route very well but Tony had his GPS so no problem. As we drove the road seemed to get progressively smaller and the darkness started to descend. We knew we were close but despite the GPS the Navstock Triangle got us. This is the name given to the maze of small roads in the area. They all look similar and wind in unexpected directions, at times it is comforting that the roadside isn’t littered with the remains of lost souls. Tony was the master of the situation and reset his GPS for point that I was familiar with and we soon emerged into country that I recognized and shortly after we turned into the farm where Joan had made us a cuppa. And so another Tiger Cub joined the collection.

By the next weekend I was impatient for a good look at the latest addition to my growing litter. So, it seemed were several others. Rob asked that we let him know when we were heading down and Angie appeared as soon as we started to move the trailer.

With a good look in daylight it was obvious that the ply that the tailgate was made of had seen better days and the ply floor also looked a bit dodgy, so it was going to take a bit of care to ease her out of her cocoon. So some support was given to the tailgate and we pumped up the tyres and moved her carefully backwards using chocks to limit her to a few inches at a time.

Slowly and carefully she emerged into the sunlight for the first time in more than 20yrs. She looked good, apart from the fabric edges lifting that we had already noted and the rubber mountings for the instrument panel had died and the panel hung on its wires and tubes.

Now, all these years after I’d seen the Tiger Cub in the magazine I had the opportunity to sit in a Cub cockpit as this was the first complete one that I’d seen since ogling Bob Adams in GMJSU at Cranfield in 1984. It wasn’t going to be easy as the firm alloy cockpit floor was well forward of the narrow opening.

In the years since I envied Bob swinging into his cockpit I’d put on two stone of lard and acquired a damaged hip. Never mind, there is very little that you can’t do if you want to badly enough, and believe me, I wanted to. On my third attempt I swung in more easily than I’d thought, just a matter of getting the method right.

The real surprise was the amount of room and the shortness of the stick. Everything fell nicely to hand especially the neat little throttle quadrant with its well made friction nut. The only gripe I could find was that to reach the altimeter adjustment was a long reach forward. All too soon it was time to yield my place to the next in line. This was Angie, who swung nimbly into place. Well, maybe she’d been watching me, after all it couldn’t just be that she was younger, fitter and a whole lot lighter than me could it? Next in was Joan who looked quite at home and it was a shame but it was out of the question for Rob to get in, he is a big lad and gallons into pint pots sprang to mind. With the state of the trailer it was going to be a hell of job to get her back inside especially as the tail wheel trolley was rapidly dying. This was partially bad news as without the trolley and with the wings folded the wing tips fouled the ground.

Angie had the idea of putting little KT behind her Yak in the hangar so we pulled the big beastie out and pushed the little beastie in with Rob putting all his weight on the engine to keep the wingtips clear of the ground as the trolley fell apart the more we moved it. As we left she looked almost cute behind the big Yak.

What a shame that she can never fly as she is, particularly as there are many nice touches in the way she’d been made, you could see that there had been an engineer involved. Still, combined with GMNKM that will be one more Tiger Cub still flying.

Postscript: We never did manage to make use of KT. Too many other jobs needed doing elsewhere and I donated her as an SSDR* project to a chap in Northern Ireland.
*Single Seat DeRegulation – see [here] for more information.

Back to the beginning: Project Tiger Cub Story part 8

Making and fitting some new bits

Some of the bonding of the foam panels to the longerons is not so good, due mainly I think. to clumsy handling over the years as the bits lay uncared for in the hangar at North Coates. Still that is a simple enough repair with a bit of care.

A trial fit of the rear cockpit section, now bolted together again, to the rear fuselage, is now due. After a lot of careful jiggling about of the clumsy components all the bracket angles are correct and the alignments right she slides together. Probably the first time in more than 20yrs most of the fuselage stands as one unit, really satisfying.
I finish that evening with a big grin on my face.

Then I fall into temptation. What I should be doing is trial fitting the fuel tank and incorporating a fuel drain as the original totally lacked one and I am almost paranoid about clean fuel. I guess I spent too long working in and around working fishing boats also I still need those seat belt measurements.. That was what I should be doing, instead I was unable to resist making up the two replacement tubes for the front cockpit section. My only excuse being that after all the dismantling checking, filling repairing and reassembling I wanted to MAKE something. I had four that were bent, damaged or otherwise unsuitable, no shortage of patterns then. Careful checks showed that, as with all the rest of the tube work they were jig made and identical. I removed the nylon inserts that I would need from damaged tubes and cut the sleeves that fit over the inboard ends of the tubes. I then carefully marked one end of each tube with centre marks top and bottom and the top of the far end of the tube. I then measured along the tube and marked the distance from the inboard end to the bolt hole for the forward bulkhead. Setting up my laser line and level gadget to give a nice clear red line centre to centre and marked the intermediate hole position with it’s centre line. Turning the tube around I marked the bottom of the tube and turning it over I then marked the bottom intermediate and extended inboard end marks beyond the length of the sleeve. Next job was to drive the centre nylon insert into position using a drift marked with the position of the insert as obtained from my patens. The end insert was then tapped into position and the sleeve glued on with epoxy. So far so good

Next thing was set the new tubes into position to ensure that my marking out was accurate. This would mean putting together the front section of the cockpit framing including the engine bulkhead. There was one tube that would not be put in place at this stage. On this tube I had to make up a throttle quadrant as the original double lever unit incorporating a choke lever needed to be changed to conform with a mandatory mod. This had come about because the double unit had  identical levers side by side. no unreasonably the powers that be decided that this was not a good idea. However the mod notification included a drawing of the replacement, so that’s another little job. Making up a spacer so that this tube could go in later I pressed on. Only to encounter another little problem, this time one of my own making. The diagonal tubes that run that run from the cockpit frame to the top of the engine bulkhead could not depress far enough. they being prevented by bolts below the top mounting brackets, some clot had put them in the wrong way around. Damn, to turn them I’d have to remove the top fore and aft tubes of the rear cockpit frame. Oh well, on with the motley, has anyone got a use for secondhand Nyloc nuts? When that is done and the tube work and bulkhead assembled I shine a torch into the bracket holes and the cockpit end and my little cross marks show nicely centered. My mood restored I slip the tubes out and drill them. Replacing them I check the forward holes and my little crosses are again just where I want them. All my pedantic measuring and aligning paid off, good stuff.

Now I ought to start getting my mods sorted with drawings, photos and calculations. As one of my main ideas is to re route the seat harness to save my spine I need to make sure that my proposed route will not foul the fuel tank or control runs. In order to sort this I’ll need to fit the tank. To do that I’ll have to offer everything up to see just how Jim Romain did it.

Back to the beginning: Project Tiger Cub Story part 7

Bent and cracked metalwork

So, on a raw autumnal morning I went back to my workshop for more than a fleeting visit. I was horrified by the clutter that had somehow gathered. I can’t work like that so it had to be sorted and sorted properly. First, the Saxon Micro drip trays just needing painting finished. That done and stowed in the shed I have a bit more room. Next, the replacement wheels for DF now just waiting for the paperwork to be labeled and stored on the right place. Then a general clean. Magic, ready to start, fire up the laptop to check with the workbook and reread the appropriate section of the Kit Build Instructions and study the drawings, it is starting to feel familiar again.

Logical order suggests that first the cockpit frame uprights to have all their plates and brackets fitted, then make up the fore and aft sub frames then join these together to form the cockpit frame. From there connect up to the engine bulkhead and the pile of tube starts to resemble part of an aeroplane again.

With so many types of plates and brackets I check the drawings in the book, read the labels that I attached when I removed them, that seems a long time ago, and lay them out on the bench. When I am happy that I know exactly where everything goes I loose fit it to check alignments, then using my supply of new nuts and bolts  making sure of a good layer of Duralac where needed.

I feel a great satisfaction as a recognizable component arises out of the stacks of labeled bits.

It is also about time that I started replacing the rejected tubes and brackets.

Firstly tube, I have two damaged forward tubes, bent by the nose wheel installation and two of the main uprights to the cockpit section have damage to the sides as if a wire or something similar had been crushed against them. Ok that is the main reason that I acquired kit 208. I am disappointed to find one of the forward tubes is not straight either but the other one and the two uprights look good. This is now a well organized process. Firstly strip off all the plates and brackets and roll it on a flat surface to check it is straight and check that all the anti-crush inserts are in place. Next a good clean down and check any marks with the trusty magnifying glass. This shows a slight deformity beside one of the holes on my last remaining forward tube, Damn. Then the messy rigmarole of the penitrant dye testing to the uprights. Messy but satisfying when as this time the developer shows a pristine white surface

So now I need a length of tube, more tube to make sleeves from and some channel and angle to make brackets from. I remember last year a mention on the BMAA web site of a metals company offering a discount to members. That seems the right place to try first. So I call them  up, friendly sounding guy on the other end has not heard of a BMAA discount but he will ring back in a about half an hour. Two hours later, no call, I ring back. Still sounding friendly he explains that he needs to speak to the States and they are not available for another hour, apologies, will ring back in less than two hours. Three hours later I ring again, he hasn’t found the channel but will ring back shortly. Next morning I ring again, he is still having trouble with the channel but can at least confirm that he is now aware of the discount offer. Leave me your e-mail address, he says, and I’ll send you a quote within threequarters of an hour. Two days later no mail, sod it, if he can’t be arsed why the hell didn’t he say so. Ah well, there are others including my old friends at Light Aero as they are now the agents for Aircraft Spruce also of high repute. So I sit down and dispatch a flurry of e-mails asking for quotes to all those that I’ve got addresses for, maybe that’ll do some good. No response to any of the e-mails, this is getting to be a pain. However after a phone call to Light Aero all is again right with the world. As helpful as ever, they track down what I need and are a bit concerned that they can’t get it to me before Christmas. It’ll have to come from America he says apologetically, but it won’t be long after the holiday. That’ll be fine I say magnanimously, it is, after all 21 December. What a damn good company.

While I await delivery of my new tube and bits I can start a bit of reassembly. First thing is to use the brackets and bits already sorted to put together the rear cockpit section. The uprights come first, then put together the torque tube and pushrod assembly. With this fitted to it’s bearings on the crosstubes I can put together the front and rear sub- assemblies. As the rear cockpit section is where the seat is mounted. When this is in one piece I can temporarily attach it to the rear fuselage giving me all the dimensions I need for the seat harness mod. Before this can happen I need to offer up the rear sub assembly to align the rear fuselage attachment brackets as the lower ones are set 45degrees to the uprights. Getting them close is easy, but things are as they should be and there is no slack in any of the bolt holes the last bit is a bit more tricky. The back of the hole being inaccessible it seems the old torch and mirror trick is the only way.

Another thing I acquired about this time was another set of main wheels, ex Pegasus as fitted to Quantums and AX2000s. Neat units, compared to the original which where the plastic wheelbarrow wheels so beloved of early microlights.

As these where innocent of any bearings I’ve always cringed a bit when looking at them. The Peggy wheels are the same diameter and same weight  but narrower, Ahh, my mantra, less drag, and fitted with bearings. They can even be fitted with brakes, but brakes are for fairies and nosewheel pilots, they are also extra weight.

Wheelbarrow wheels first, another mod for later, although it is very tempting to get side tracked

Early in January my package from Light Aero, or LAS as they now like to refer to themselves, arrives. As I have come to expect from them everything is there and 100% correct. Also the paperwork that accompanies the delivery is the kind of thing that Tec Office goes to bed dreaming about. As good as always, thanks guys. When I’ve opened the package I check that the tube that sleeves two of the others fits, and it does, perfectly. I feel a very strong urge to start making the brackets ect. Discipline prevails  and I regretfully tuck it away until the right time in the build sequence

It’s time to start checking the rear fuselage and it’s not a good start when one of the attachment brackets turns out to have an elongated hole. Sod it! still kit 208 comes to rescue again and that bracket checks out ok. The elevator push rod comes next and that also is fine, then the rear aluminium bulkhead.

This is a bit more complex, with its edges pressed over to just a bit less that 90% to the main plate, attached brackets for the longeron ends and attachment holes for the rudder post. The only way that I can think of for this is carefully, a bit at a time.

After spending most of a day checking bends, corners holes and rivets it all proves to be in good shape Whew.

Back to the beginning: Project Tiger Cub Story part 6

Dreaming up some improvements

Next came a bit of a rethink, I’m looking at so many mods that this job could take forever. Maybe it would be better to take it a bit at a time instead of trying to bury Tec office in paper I’ll do it in stages and sneak up on them. The first thing to consider seems to be which of the mods is best built in when the aircraft is reassembled and which can be readily altered or added later? OK

(1) Engine cooling, as built the Cub had a large hole though the firewall, This allowed access to the recoil starter which filled the hole. An early mandatory required the removal of the recoil starter as the engine mounts were fixed to this and the starter casing proved unequal to the task. After cracking was found the engine mounting was modified which involved the discarding of the starter and it’s housing. This of course moved the engine much closer to the firewall. Engine cooling at this stage was still fine until another mandatory mod to restore the integrity of the firewall insisted the  hole was covered by a plate. Whoops, nowhere for the hot air to go. Right what was needed was another mandatory mod to turn the cylinder heads to an angle to improve the flow. Most Cub owners also fitted a duct from the firewall plate and out though the floor and that mostly does work. I wanted to experiment with fitting a scoop to act as a sort of venturi to improve the airflow from the rear cylinder. That I think can go on the to be done later list.

(2) Seat Belt mod. As the present layout for the shoulder straps makes me shudder when I think about the effect of an accident on my spine. The reason for this is also in the chequered past of Cub mods. The tank was first mounted clear of the fuselage to the rear cockpit sub frame at about pilots head level. Although this had advantages, it was removable for filling and was clear of the blue foam that forms the structure between the longerons (petrol has the nasty habit of dissolving blue foam) it was possible for it to blank the tail surfaces .So It had to be moved. The U section channel that the tank was supported on also act as the anchor point for the shoulder harness so, of course this moved also. The mod involves lowering the tank so that it is within the fuselage taking with it the harness anchor point. This made the harness ideal for compressing the spine in the event of even a minor prang. I was not happy with that as I have no ambition to learn how to drive a wheelchair. The mod that I want in place  involves running a cable from the aft bulkhead though the rear fuselage and adding a raised section to accommodate the strap attachment at the correct level. I hope that I can make that resemble the elegant hump that the SE5 sported. I guess thats one for the initial build list

(3) Tank Mod. As I said before I have two Cubs and only one Cub Tank the other one having ended up fitted to a Rans at North Coates. I do however have a 25ltr Thruster tank and this is a superior item in every way and that is the one I prefer to fit in the first build. This will mean making a mounting system that will withstand 6G when full and as it is aft of the C of G the weight will need to be carefully monitored. Alternatively I can redesign the fuel pipe system to fit a drain valve at the lowest point. That’ll do the job, even if it isn’t such a neat solution. No mod required for that, so my first build will go that way.

(4) Undercarriage. As I mentioned before I intend to revert to a tailwheel undercarriage because it’s lighter, tougher and creates less drag and besides it looks a hell of a lot better.

I also intend to have the main wheels strut braced like the main wheels of the nose wheel undercarriage. As this is effectively a new layout it will require rigorous testing. I do have a set of the standard wire braced main gear from SU.

So I think that I’ll fit this initially thus just reverting to standard Cub undercarriage, no mod needed. I can develop the strut braced version later.

(5)  Streamlining. All those round struts. They are everywhere, wing struts, cockpit struts, undercarriage struts and they are all round factually and figuratively. the drag must be horrendous. Weight of course could be an issue but I’d have to dismantle most of the aircraft to fit them later. So, one more for the initial build list

(6) Clear vision panel…

Whilst the view from a Cub is pretty good for a Bi Plane you just can’t have too good a view so I’d like to make a centre section with a large clear panel though it. That will give me a better chance of spotting those Class A pilots that spend too much time playing with the toys on their instrument  panels and not enough time looking out.

There does appear to be increasing numbers of these. As I have two centre sections I can work on this and add it later. One more for the deferred list.

So, lets see, that’s two mods to be incorporated in the initial build and three to be developed later. That should make life bit easier.

So from these first two a logical order appears. Number one assemble the cockpit sub frame and fit seat. Next make the tank mounting and fit to sub frame. Fit tank and straps check clearance from seat. Offer up to rear fuselage and check clearance from control runs. Load test tank and mountings. Photograph, prepare drawings and write out mod submission.

Number Two, while front and rear fuselage sections are together determine height needed for shoulder strap attachment. Ensure wire from rear bulkhead can reach this without interfering with any of the control runs. When sure that it will work buy the new harness. Then when work to the tank is completed run the wire make the.” hump” from ply and lath ( shades of a Hurricane) or to make something from blue foam which may be lighter. Then as before with photos, drawings and writing.

Number Three, The streamlining. First look into the weights of the materials available, alloy, glassfibre or maybe even carbon fibre. submit mod as before. Fit to tubes on final assembly. Simple innit (OH Yeah)

Just in case there is any problem with runs of the harness rudder cables I’ll fit the tank mount for testing purposes to the cockpit framing from kit 208  from the Cub that was never completed. So taking them out of store I put them together, now with parts to be included in the build and parts that won’t be both in the workshop I must continue to be meticulous in my labelling and stowage. It is both satisfying and exciting to watch the first bits really taking shape .To satisfy my curiosity I try fitting parts from SP, SU and KM to the structure of kit 208 and they all fit. Obviously jig made, but as SP and SU were quite early in the production of the kits and KM and 208 were quite late it does wonders for the confidence.

Then before offering up I need to place the elevator control rod in place in the rear fuselage section . Then I need to run two strings to follow the course of rudder cables to ensure that there no danger of anything chafing or obstructing.

Having got this far life got in the way. The runway at Sheepcoates Farm was now operational so there was grass to cut and roll, huts to build and decking and slabs to lay.
Also the need to fly, preferably DF. Hell that is so close to addiction, almost like being a druggie.

So poor SP once again in her life was neglected. This time it was only for 4 months but on my visits to the workshop once or twice a week to turn over the engines I felt very guilty until the great day I could go back to restart work.