Here is a list of all the postings Bob Howard has made in our forums. Click on a thread name to jump to the thread.
|Thread: Laser Engines - Technical questions|
Most important question of all - how is the move going, and when will everything be back in production?
|Thread: First glitch ever|
A couple of years ago, one of our instructors reported elevator glitches on 2.4GHz. Later, the wing of the model broke in the middle!
A couple of weeks later two more trainers also sufferred what appeared to be elevator glitches. It turned out that all three models had poor quality wing bands (supplied in the ARTF kit) which were allowing the L/E of the wing to lift, giving the impression of an elevator glitch.
Stronger wing bands cured the problem, and we now advise all of our beginners to throw the cheap bands supplied with the kit into the bin, and buy proper ones.
The broken wing was amost certainly due to L/E lift causing a sudden increase in lift, overstressing the wing.
How about hitting them with our "Human Rights".
If a convict justly serving a sentence in one of HM Prisons can claim all manner of rights, so can we!
|Thread: Foam Cutting|
My bow also just over 1m long, Dural tube handle with nichrome wire attached to insulated springs. I have a feeling that MFA made something very similar some years ago, but I have no idea if it is the same one.
What dimmer & transfromer do you use?
Some time ago (2 - 3 years) an article in RCM&E contained details of a DIY power supply for use with a bow for cutting foam wing blanks. I feel sure that it was a letter on the "All Write" page.
The power supply was built from various bit from the electical department of B&Q, including a dimmer switch and a transformer intended for domestic halogen spotlights.
I would like to have a go at making the power supply (or having one made by a qualified sparky) & cutting some wings. I already have the cutting bow, but I have lost the magazine with the article in it.
Does anybody have the magazine article,or any details of what items were used, and how they were wired up?
|Thread: Laser 80 Engine|
You have it spot on - all Lasers had the owners initials stamped on them at the factory before despatch. I am not sure if they still do that.
The bearer width of 40mm was common to the 61, 75 & 80, as are the mounting hole spacings. The 61 was the first laser ever produced, the 75 followed it a few months later.
Come to think of it, it could even be a very old 61. The only external difference between the 61 & 75 was the width of the cylinder head, but I have no details to hand what the difference was. You could always email Neil for information.
Re. my Laser 80 with a blocked silencer, I struggled with that problem for months. Neil diagnosed it from a single email. It has been running like a sewing machine ever since.
Definitely a 75, so the prop sizes suggested will be fine.
The 70 is much smaller, and has the modified carb/exhaust fixings and plug position.
Go to www.laserengines.com. The instructions are all on the website.
I am not convinced that your engine is an 80. The plug is inclined forwards, and the silencer & carb are held in by 6BA grub screws. Both of these features were redesigned when the 80 was introduced. Check the mounting dimensions against the data sheet on the Laser website. If the 80 dimensions match your engine, you have a 75.
Stripping down could be a bit tricky, as the cams tend to fall out if you remove the backplate. You will probably never get the timing right again. When I acquired an old Laser with the valve gear gummed up with oil, Neil Tidey (Mr. Laser Engines) advised me to use cellulose thinners - it worked. Remember to give it a good oiling afterwards.
If the valves are coked up, running on synthetic fuel should clear them out a bit.
I notice there is no carburettor fitted. The original Super Tigre carbs (simple wire needle valve, with a locking nut) were great. I have a laser 75, about 25 years old, which still runs perfectly. The later S/T carbs, which yours would probably not have had, were fitted with seals which could develop air leaks. This made setting up a bit tricky
If you have no carb, is worth investing in the latest version, designed by Neil Tidey. It works fine, and should cost about £30 - £35. You might need to replace the silencer as well (£12). I had a secondhand Laser 80 which insisted on overheating and stopping - it turned out to be a blocked silencer.
Your engine has a pressure nipple on the side of the silencer - you should not need it. All of my Lasers have always run well withour pressure.
I run my engines on Model Technics Pro-Power 5% fuel, Firepower F6 plug & , for a 75 or 80, an APC 13 x 9 prop. You could also tru a Graupner 12 x 8 3 blade.
Good luck & happy Lasering!
|Thread: locating a manufacturer|
I understand that Skyways models are back. Masons Models are only issuing the Chippahawk (semi-scale Chipmunk), Hawk 70 (Magister/Moth Minor look-alike) Stampe SVB Biplane and Hawk Tiger Moth at the moment - lets hope the Moth Minor, Yak 18 & Akromaster are not too far behind.
These are builders kits for proper aeromdellers - not the ARTF junk that pollutes most flying fields these days. Having said that, they are not too difficult to build - foam wings & top decks, simple balsa box fuselage, strip ailerons etc.
Have a look here.
|Thread: Info on new plane|
Are you related to Terry? He is much missed.
|Thread: The October Grand Prize Draw|
One of our newer members turned uo at the field this spring with the WOT Trainer. Chris Foss has done it again!
It took our lad from raw beginner, through to simple aerobatics (which it does much better than other trainers) to his A Certificate.
One bonus with the WOT-Trainer - no nose-leg to bend.
There is a saying in full size (vintage) aviation - if pilots were meant to see where they were taxiing, they would have been born with telescopic necks!
Long live the tail-dragger!
|Thread: Coloured dope|
It is overweight now (like the builder/pilot!).
Actually, I fuel-proofed it all with Flair Spectrum, The problem is not the glossiness of the top coat, but the way that light reflects from the base colour. Too much light is absorbed.
Incidentally, I had problems with this particular finishing method. The Spectrum does not seem to bond well to the acrylic, and it is peeling. I was surprised at this, as others in my club use spectrum with excellent results - just an unlucky mis-match I suppose.
This is another reason why I need to strip the model and respray - using a more sensible colour scheme!
I am now using Profilm on all new models!
A looked into this, and was told that cellulose is really only banned for major use (e.g. car manufacture etc). It is still available for "specialist" use. This includes, for example, hobby applications and restoration of vehicles originally finished in cellulose.
I had an interesting chat recently with the manager of my local car paint suppliert. Many years ago, I finished a model in Ford Arizona Gold (flash swine that I am). It looked great, and showed up well in the air.
A couple of years ago, I finished an Acro-Wot in the same shade, but using automotive acrylics. It was nothing like as bright, so such so that orientation was tricky anything less than bright sunshine. When I asked the chap if he had any ideas why, he suggested that acrylic has lower levels of reflectifvity than cellulose.
I am now trying to find a way to get all the paint off, down to either the glass cloth or, better still, the wood. I learned a long time ago (the hard way) that using paint stripper (or thinners for that matter) on a foam wing is not a smart idea! Short of taking a 6 month holiday from work and buying a job lot of wet & dry - any ideas?
|Great - love to see some piccies.|
|Thread: Wing Bands|
Just a tip fo all beginners learning on ARTF models - and for their instructors.
We recently had a spate of models showing an sudden tendency to pitch up from level flight - in one case this was so sudden that the wing broke.
We initially suspected interference of some sort, but when a model on 2.4gHz started misbehaving we knew we needed to look further. We eventually realised that the models affected had the wings attached with the original rubber bands supplied in the kit. They allowed the leading edge of the wing to move, which produced a sudden dramatic increase in lift.
Either the rubber bands were not up to the job, or they had aged & weakened very quickly. This was not restricted to one make or design, so I would urge you to check the wing bands.
Pick up the model by the leading edge of the wing, close the each side of the fuselage. Shake it up and down vigorously. If you can hear the fuselage and wing banging together, replace the bands.
I have also noticed that many flyers use only 4 bands. I have always advocated 6. The first 2 are crossed over, the second 2 go straight from front to back, and the last ones cross over again.
Finally, please do not try to make it all look nice by sanding the ends of the dowel to a smooth, rounded shape - this only encourages the bands to slip off. I often glue a drawing pin into the end of the dowel to make a lip, which keeps the bands in place.
|Thread: Resin/hardener ratio for Ripmax SP Epoxy?|
They did 2 types of SP resin.
If it is SP113 (it probably is) then 3parts resin to 1part hardener by volume.
If it is SPX 5000, 5 parts resin to 2 parts hardener by volume OR 3:1 by weight
I notice some shops are stocking SP113 again - it was good stuff.
Re. Andy's suggestion about varying the mix :-
With polyester (the smelly stuff from Halfords), all of the chemicals neeeded to effect a full cure are in the resin. The so-called "Hardener" is only a catalyst, which sets off the chemical reaction. More catalyst, quicker cure.
With epoxy, each of the constituents contain a given quantity of the various chenmicals needed for a cure. If the ratio is not fairly accurate, some of the chemicals will remain in an uncured state. Too much hardener will result in a brittle mix with reduced strength, too little results in a cured resin a bit like cheese - soft & rubbery, again with little strength.
Nowadays I use Deluxe Products Aeropoxy for skinning, mouldings and joining foam wings. If I remember rightly, the instruction leafelet suggests a maximum tolerance of 10% on the mix ratio (3:2 in this case), but I try to be spot on.
For building, my policy is to always use a slow epoxy. Not only does it give longer to work with, but the joint is far stronger. I sometime stir a small amount of filler into the mix to add strength - either milled glass (from Great Planes) or Kevlar pulp (Fibretech).
|Thread: Coloured dope|
|What are you painting?|
Be careful with Brodak. It is a Butyrate dope, not Nitrate like the normal stuff. It is superb stuff, but the two types are not compatible. If I remember rightly, you can use Butyrate over nitrate (not recommended though), but not vice versa, as the nitrate pickles the butyrate.
Brodak produce their own Butyrate clear dope. I would use that, together with their special thinner.
Butyrate is claimed to be more fuel resistant than Nitrate.
Alternatively, why not try common or garden Solarlac. Most model shops stock it, plenty of colours to choose from, it is flexible & fuel resistant. The only thing I would suggest is, use a retardant cellulose thinner from your friendly local car paint store (e.g Autocolours). The Solarlac thinner is OK, but it dries a bit too quickly for my liking. If you are using an airbrush, the paint can be dry before it hits the surface!
Solarlac can be applied over Nitrate dope, but I have also tried using Clearcoat instead of dope. Seems to work OK on sheeted surfaces (e.g. with tissue). It does not shrink much, which helps to avoid distortion of the wood, but I doubt if it would be any good for nylon or tissue over an open structure.
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