Engine Doctor

Well done will look forward to see the film. Edited By Engine Doctor on 21/10/2016 10:33:59

Twist the warp out further than needed and then apply heat using hot air gun on both sides of the wing until all twist or signs of stretching on the covering dissapears and covering is taught . Hold for a short while until it cools. Now iron over the covering where it touches the ribs etc ,this will help stiffen the wing by fixing the covering to the structure . It should go back to proper shape but may need a couple of goes to stay where you want it. If the adhesive on the covering has deteriorated then it s a strip off job .If the wing has a "D" box front section thats warped then you mayhave to strip it and remove the back of the D box( vertical spar bracing) to re set it. What glue did you use when you built them all those years ago ? Might be worth stripping off the covering and checking the structure anyway . Good luck with them . Edited By Engine Doctor on 17/10/2016 09:51:56

Erlog mentions the possibility of a resident club at the proposed NFC in his last post .I have no problem with a resident club at the NFC should it become a reality ; however I feel they should pay a realistic rent for the use of the site as other clubs have to and not be subsidised by every other BMFA member . It certainly is doable and hopefully our annual meeting " The Nats" can be secured for the future. 

You may find that the con rod is stuck on the gudgeon pin , this in turn stops it from sliding back off of the crankpin. Try soaking in some boiling water for a few minutes . Once it can slide along the gudgeon pin it should clear the crank ok.

This sounds like a good question for our politicians to get their teeth into . They may even propose a giant conveyor for the new runway required at Heathrow or Gatwick . Should have been saved for April the first .

Hi The discussion re the aileron flutter on the T180 is worth noting .I was asked to test fly many of these when they were current models . Somwe were badly built and I refused to test them until faults were rectified. The one that stood out was an immaculately built T180 that the builder had been really been careful with the build making sure there wasn't any noticeable play in the linkage. It was a breezy day but not excessive . Long story short , the ailerons fluttered and one ripped off . I managed to land the plane with the loose aileron dangling in the breeze ! The air speed needed to make headway into the breeze was enough to start the aileron flutter added to the poor linkage design and rubbish hinges and bingo a aileron failure . The wing was repaired and the aileron linkage replaced with a servo for each aileron with short stiff linkage and some decent hinges . No problem after that

I forgot to say that Clearcoat also works well against higher nitro fuels. I used it on a kyosho Majestic ARTF that powered by a YS 63 running on 20% nitro . It now ten years old , looks good and still not fuel soaked.

Hi try Clearcoat . I can thoroughly recommend it . It's made by the solar film people and it's very good.  I have tried all sorts of varnishes ,epoxy and two packs but now only use Clearcoat as it easy to use straight from the tin doesn't discolour and also easy to clean off with cellulose thinners if spilt. Use it on any areas that might get fuel contamination. Use it  before covering the model especially the engine bay, fuel tank bay and around u/c mounts etc . It's not very expensive goes a long way almost importantly , it works . It will also seal and improve the adhesion of your covering material and really does prevent any fuel creeping under covering. The only down side to it is that it has a strong smell when drying but does dry pretty quickly. Leave to dry overnight before covering . It can be thinned  by up to 10% without affecting it's performance . I use cellulose to thin it and have not had any problems. I use a thinned coat and allow to soak into any wood then a full strength coat . Hope this helps.

You should be able to buy the same /similar product from a car paint factors for far less .or this perhaps from Amazon https://www.amazon.co.uk/Autotek-AT000FP500-500ml-Filler-Primer/dp/B004ZJIM8O . There may be others on E-bay They are all very similar but very heavy . They will also dry sand when fully dry without clogging the paper . What dope are you using to fix the tissue ? It would be interesting to know what to avoid if it clogs when sanding. Great looking build , very neat . E.D.

Hi Mr B. Looking at your pics again the rocker cover has a hole punched directly above the pushrod . Is it possible that its over revving in dives ? That could explain the failure and the hole punched in the cover although I would expect some valve damage as well ; or did the broken part find its way to the area  between the push-rod and cover? Edited By Engine Doctor on 09/10/2016 11:10:18

Posted by Glyn44 on 08/10/2016 09:34:49: I will put money on it that it is the opposite direction to the way I have put in mine over the last couple of years. I can see a really annoying job coming up here! It might be an annoying job but you won't get it wrong again . If you have put them in the wrong way the sharp end of the insert can cut into the wooden bearers allowing the screws  to loosen and eventually fall out causing loss of control .  Edited By Engine Doctor on 08/10/2016 10:05:10

Hi Sorry for confusion I wasn't suggesting that the broken bit was welded back on as that would be too small but that metal is welded back onto the support then reshaped and drilled to support rocker spindle . Thinking on ,the heat generated may adversely affect the chrome plating of cylinder walls.

Hi . Check if the exhaust valve is free to move and that the valve spring is ok and able to seat the valve easily. If the valve stem is tight in the guide then extra pressure is placed on all the valve gear and an upward pressure on the rocker support. I've never seen one of these fail in use  before but have seen them damaged in crashes .You won't be able to salvage that head by the looks of it as the rocker supports /pedestal are part of the casting, unless you know a good Ali welder who can rebuild broken part. It's still good to know what caused the failure so as to avoid it in future. If you intend to replace the cylinder it's not a difficult job but do replace the valve springs at the same time . The last Saito I replaced the cylinder and carb on,an 82, the bits cost about £120 ish from memory. Let us know how you get on. Edited By Engine Doctor on 07/10/2016 12:17:30

Hi had a wot 4 powered with an OS 60 2s . I had a set of Classic  wings and a set of Mk111 wings . The plane flew very well with unlimited vertical power . The downside to the bigger engine was the extra weight made it land fast. The tapered Mk111 wing was IMO more fun to fly with less drag . Never found the need for air brakes etc. A low slow circuit for landing suficed . IMO still the best all round fun model.

Posted by PETER BRUCE - Eastchurch Gap on 04/10/2016 23:43:56: Tuesday Night - No reply yet from Ripmax regarding the video... Hi Peter . Don't hold your breath for reply ! I knew a person who left customer service because his hands were tied on what he could do to help customers (hand tied metaphorically of course , if they had really been tied he would probably  be happily still working there ) Be careful with the horns you have replaced as well. I used them , or similar design some years ago and the bolts snapped on the threaded portion of the long bolt where it exits the  mounting plate. This happened after a flying session with a 50 cc sports job when unloading from car . I don't trust them anymore with the screws/ bolts supplied .  If it had let go in the air then that would have resulted in a crash .Check a bolt and see if it's brittle or soft .I now usually make the horns from either Paxolin or carbon fibre sheet and epoxy them into the control surfaces. I then connect them with either ball joints or good quality clevices , with 3mm rods for anything over 60 inch span or 0.50 cu engine.

The synthetic oils that were available when your Saito was current were poor by modern standards so castor was the prefered oil . Like most things, that all turned around completely now as synthetics have improved so much. Definitely run it on synthetic . I won't use anything else these days . 

Change no 10 on list to " Do I want it ? " If the answer is yes then buy it 

Posted by AndyD on 02/10/2016 22:53:26: ,i was given galf a gallon of laser 5% the other day but somebody told me i shouldnt use it in my asp 4 strokes as it as no castor in it,surely thats bunkem with modern type oils or is it a warranty thing,mine are well used so deff out of warranty. Your correct definitely dont use castor oil based fuels in modern engines beit two or four-stroke. Castor was fine for older engines that didn't produce the power or heat of the modern engines. In extreme cases it turns to a varnish that plates moving parts like pistons valve stems etc. This varnish cause all sorts of problems from overheating to seizing. Modern synthetics are far more tolerant of heat and keep engine internals clean . But do be careful not to run your engine lean , that will still damage an engine and the oil is often blamed.

Just tried https:// www.bmfa.org  and works fine ?

Engine looks well baked . Is the exhaust valve stiff in its guide? A build up of varnish and carbon can cause this problem . If the valve stem gets stuck then the pushrod can come out of its setting in the rocker and pushes it further and through the cover. Our cars used to do similar thing years ago when oil was poor and petrol contained all sorts of rubbish .Forumites of a certain age will remember . A de-coke was needed every So often to keep them running properly .Model four strokes can be affected similarly  by castor oil if not cleaned and serviced now and again. The chip pan appearance of the head and silencer could be castor oil baked on and will be similar inside the engine. What fuel have you been using ? Edited By Engine Doctor on 02/10/2016 11:00:02

I have built and assembled many kits and ARTF flat packs for mates and club members and nearly all supplied hardware is junk. Some of the problems I have encountered include; Tanks are poor quality and often split at the neck when assemled or leak at neck after a couple of weeks. I have even had clunks where the hole doesn't go through the centre so no fuel can get to engine! The brass tube supplied is the poorest quality available and turn blackor develops pinholescausing engines to stop and breaks if any nitro fuel is used .The threaded wire , so called piano wire is either like binding wire or so hard it snaps when bending and clevices are poorly threaded, occasionally sliding along the threaded rod as if two different threads were used, and have occasionally snapped when fitting. Control horns made of a bendy nylon type stuff not fit for purpose . I would definitely pay another £10 or so on a kit to get decent hardware or better still leave the junk out of the box and supply my own. This use of poor quality materials has even spread to the wood used in kits. So called plywood that resembles laminated matchboxes (remember them) with hardly any glue to hold the laminates together ! Cheap is not best but nowadays even expensive is often rubbish as well ! These poor quality clevices were supplied with some very expensive super scale models by a well known supplier. These kits were in the £500 plus range. They were well aware of the failings and chose to ignore it ! Have a good look in a kit before parting with your cash . If the hardware is c*** then get the dealer to supply some good stuff. The message will surely then get back to the wholesalers. Edited By Engine Doctor on 01/10/2016 10:33:14

Posted by Phil Claridge on 24/09/2016 18:16:04: hi there, i have just bought a DB excel with a saito 30 upfront i got this plane at headcorn for £30 complete with 2.4 futaba reciever and all servo.s i think the engine alone was worth that regards phil BARGAIN! Thats a cracking buy even if the airframe is rubbish. Well done for spotting it, If I had spotted it first you wouldn't be posting here . Well done. Use props sized as per Johns post go for the higher pitches as four-stroke tend to be lower revving than two strokes. I'd try the 9x7 first and see if the engine is happy with it . If you don't need the speed then lower the pitch and increase diameter .

Hello Martyn. You wont be dissappointed with the Eurobat , its a great flyer with no vices. I have one that's about 8 years old now . It even survived a mid air that wiped its tail fin off ! I have a CRRC pro 45 in that that has loads of power . As you have said the down side of the ST is the fuel consumption. be sure to run in well before flying it as the rings on the all the big ST's can be a bit on the tight side. I haven't owned one of those for a few years now but the last one i had I re-gapped the piston ring and it improved the running . The Big Brute has a much lower oil content ,10% if my memory is correct ,as the larger glows don't need as much oil . Good luck and enjoy the Eurobat . PS. Make sure you iron down the covering on the Eurobat well before flying as mine was very loose and came away when new. PPS. Is there another set of Eurobat bits ?

Hi Have you tried using Clearcoat fuel proofer as an adhesive ? I have used this method for years and found it far superior to Balsa lock. Solarfilm recommend using it on areas before covering, that get a lot of fuel on them like cowls etc so I thought I would try it on other tricky to cover areas . I have used it on under cambered vintage models with no problems so it may be helpful on your model. The top of the wing shouldn't need it and can be covered in the normal way Apply good wet coat of Clearcoat straight from the tin to the areas of the frame/balsa where you require the bond . Allow to dry thoroughly over night then apply a thin coat and leave to dry for about an hour before covering . As Cymaz  suggest start from the middle at the inner and outer ribs pulling the covering taught then tack to all the ribs working out to the leading and trailing edges . The heat from a covering iron will reactivate the resin and give an immediate bond. Keep the temp just hot enough to tack the covering but not hot enough to shrink the tex . If you are not happy with application you can simply apply the iron and re-position the covering.Try to get it applied as smooth as possible . When happy turn up the heat a little and go over all the contact area and iron down firmly . Cover the top of the wing then shrink as required with a hot air gun being careful not to over heat/shrink allowing the Tex to pull away . I also use this to adhere Litespan and have model that are now years old and all covering is still well stuck down. Edited By Engine Doctor on 17/09/2016 18:51:55

Another for Clearcoat . If you need to thin it ,up to 10% or clean brushes then cellulose thinner is fine . The enamel fuel proofers like spectra can yellow with age and look gruby.they generally take a long time to dry and cure before being fuel proof/resistant . No fuel proofers really adhere to the glossy side of covering films very well but its not really needed as the film is fuel proof. The edges are vulnerable to fuel residue creeping under the covering and as already suggested ,give the edges a good coat. If you want the Clearcoat to adhere to the glossy film then give it a coat of "Prymol" its made by Solarfilm for use with Clearcoat and Solarlac colours. It is also heat activated and will really stick covering to any balsa when covering or recovering you do .Do allow it to dry thoroughly before covering. It works very well with solarfilm but not all coverings Clearcoat is quick drying but the vapours do smell very stongly so use in a well ventilated area or bear the wrath of the family! I would also give the tank bay a good coat of Clearcoat as any leaks will ruin the model