skippydiesel

FYI; Most suppliers of SCEET & SCAT are now selling in lengths of 3 ft to 11 meters BUT tend to quote in the cost per foot (to suck you in?). This can be quite expensive stuff to buy especially when only a small length is required and you are forced to purchase the minimum? SkyShop would seem to be in a minority of one - they quote & sell per foot SCEET - 8 (2in) @ $25.20/ft 😈

Hi Planey, Thank you for your kind & encouraging words. It seems to me that small/compact LA's would have many applications in small experimental aircraft, however this will not happen until they can be made reliable - a few hours of operation (cycles) before giving up the ghost, is not reliable. The reason for my optimise is simple - I find running electrical cables far easier than trying to do the same thing with the traditional levers & pull push cables.😈

It would seem that a compact/small linear actuator, with proven reliability, does not exist. There are much larger/heavier units available but then there are questions of space to fit and weight to consider, along with changes to existing bracket, shape, size/location. There have been not so subtle suggestions that I should avoid Chinese suppliers - FYI I have yet to find a single supplier who does not have his LA's made in China. I think I will fall back to a very simple system, that I have used on another aircraft to good effect - a winter & summer fixed flap. This will likely be a single flap with removable/replaceable air flow "chokes" ie more "choke" for winter less/0 for summer opps. Somewhere "down the track" a suitable LA may come on the market.😈

Me thinks you take the analogy to literally - so I will answer you in the same vain: If one or more of your control surfaces is jammed, due to the "Home Depot" plug having come loose, no amount of gas monitoring will save you🤣 "Besides, you should have a working CO monitor in any aircraft cabin to ensure you don't get accidentally poisoned by toxic fumes." You betray yourself, in your absolute confidence/dependence on third parties to make decision about your homebuilt aircrafts servisabity - Monitors do not prevent poisoning or anything else. They inform (IF working correctly) & IF the pilot takes note/notices, of a potentially dangerous situaton -IF!!! the pilot is in a condition to ameliorate the situation, they may save themselves. You could inform yourself about the quality of alternative parts but Noooo!, rather delegate this to a (usually) unknown person(s) who will issue you a piece of paper, inferring quality/suitability. As always I support your right to make your own decisions in this area. However find your logic both wanting and now, apparently, inconsistent.🤣😈

You guys - you want your cake and then when it suits a non certified cake. 🤣 It is now a fact, that you, will use a non certified/non OM supplied item, when/ where it suits you to do so. Your rigelling smacks of hypocrisy.😈

Oooooh! selective with our arguments, aren't we??? I think my point is clear enough - if a highly respected certified aircraft, advisory organisation, can recomend parts from a hardware store, the principal of substitution (where appropriate), is well and truly established. "It's only plugging off a cabin heat ducting ." - so? How do I know that the "plug" will not deteriorate rapidly, allowing toxic fumes to enter the cabin or fall out & interfere with the aircraft control systems, etc etc?? ".........for use as critical flight components" - what might the definition of "critical" be in this context?? Could it be a part which meets/exceeds all of the published (in my situaton by Rotax) specifications OR as you would have - supplied by the manufactures representative (dealership/agent) on trust with a bit of documentation attached & a high price tag??? 😈

I am an advocate for using less costly, non aircraft/certified/OM supplied parts, in the maintenance of experimental/homebuilt aircraft (particularly Rotax engine service components) subject to appropriate research of the proposed part. I am often receive very strong opposition to my advocacy, so its with some delight that I reference a small section of advice from a highly esteemed/respected organisation - The Bonanza Air Safety Foundation, "Detecting and Preventing Future Aileron Cable Damage Recommendations for Voluntary AD 2019-23-10 Follow-On Actions ABS Air Safety Foundation"; "If you do not require heat in the baggage area or aft cabin behind the 3 rd and 4th seats, remove the original ducting completely. Install a 2” PVC plug (Home Depot SKU 741 264) inside the plenum to which the original duct is attached, then use a #36 stainless steel hose clamp (Home Depot SKU 100 494) to tighten the hose around the plug. The clamp and plug may also be purchased from any of the building supply stores. You will need to sand the plug’s outer diameter down slightly to install it inside the flange with a tight fit." I believe "Home Depot" to be a hardware store chain.🤣 😈

Thanks mate!😈

Hi Gareth - which type do you have, SCEET or SCAT ?

??????????😈

What!!! Not a one with a bit of leftover SCEET ?? What about SCAT?😈

Looking for a short length of SCEET ducting , ID 2" , often referred to by Dash Number -8. 300mm/1 ft would be ideal. Will consider longer/shorter. Living in hope 😈

It is almost certain, that manned fighter/bomber aircarft are close to being redundant - the future will be drones & rockets of all shapes & sizes. This trend is also going to happen on/under the sea - so much for billion dollar subs. Military personnel will be a long way from the front line and relative, to past/current conflicts, few in number. The featured aircraft, if it isn't a computer generated fraud, is but part of a game of one upmanship - a distraction/propaganda 😈

Cowl flap is the full width of & conforms with, the shape of, the underside of my cowling and aproximately 150 mm wide. Hinged at the afte edge of the cowling (no possibility of jamming). When closed, conforms with/looks like, an extension of cowling bottom. When open, goes to about 45 degrees down, Will try & find a photo

Ah! 😈

I don't follow. I have been using LA's with a claimed 19kg extension force - many times what might be required to open a small flap, to say 30-45 degrees. The pressure, on the closed flap is minimal, as its function is a "choke' or restriction, not shutting of the air flow completely. The lower closing force of the LA is equally of no concern, as the air pressure against the flap will assist the retraction. The LA's, for their short life, have worked well. As earlier mentioned - a post-mortem of the first LA found that the motor still ran, the extension/retraction system still worked, however the stroke limiter circuit had failed, thus not allowing the reverse of current polarity to retract the system. The following are the specifications I have been working to: · Some resistance to moisture, dust & temperature. The actuator may be inadvertently exposed to water, during cleaning and in operation, air temperatures to 600C. · Extension range 20-25mm. · Working speed 5-10mm/sec (negotiable) · Thrust 20kg (negotiable) · Installed length (retracted) 75 -80 mm · Fully extended/retracted, built in, electronic limit switches (existing remote switch to reverse polarity/direction of movement) · No power “lock” in fully extended/retracted position. · Constructed of corrosion & vibration resistant materials · Current mountings 4mm ID both ends but could be modified. · Automotive standard 12V electrical cable The extension of 20-25 mm, will give an approximate 45 degree flap movement.😈

"repeated stalling of the actuator against a fixed load will shorten the life of the actuator". I do not understand. The LA's I have been using have two wires. Switch down - current drives motor - system extends - "hits" stroke limiter and cuts off current. Switch Up - current reverses motor - system retracts - "hits" stroke limiter and cuts off current. Note: There is no need for an interim position ie its either fully open or fully closed The above system can not repeatedly stall, as stroke limiters shut of current/drive at the end of each stroke movement. 😈

Nice one Garfly! 😈

Hi onetrack. This is the smallest 25 mm LA that MOTIONDYNAMICS have on their web page: This is dimensional idea (not the actual unit) of what I am after:

Correction: I am great admirer of the Chinese and their work philosophy. Industrially, scientifically & possibly militarily we have much to be concerned about - they are consigning us (the West) to history. In my lifetime I have seen the rise & rise of Asian industry. Look at the high quality products from the Japanese & Koreans - in my youth much sneered at. The Chinese & Indians have put rockets/satellites into space. Sure they give the World cheap low quality products but they can & do, deliver as high a quality as we are willing to pay for. Thanks for the WWW.MOTIONDYNAMICS.COM.AU - I have written to them asking for their recommendation - Unfortunatly my browsing of their website, suggest even their smallest actuator is likly many times the weight/size of what I would like.😈

My friend, is it possible, that you did not read the proceeding comments, from me? The traditional system(s) of Cole Flap actuation, present a series of chalanages, I do not wish to address. The electrical solution, long since adopted in the automotive world , is my proffered concept. The concept has been tested - It works! - fact! Unfortunatly I have yet to find a suitably robust Linear Actuator of the correct specifications, that will give a durable service - this is why I asked the question in my opening comments. So I ask you again -Are you able to recomend a supplier of quality linear actuators that may suit my purpose??😈

Thanks for the correction in terminology. ".......I could knock up a simple one for you in probably less than an hour." As for simple - perhaps I am overcomplicating, the system, in my mind; Ratios to be considered - Input length of actuating button movement : reversing arm linkage length & location of input/output cables : flap movement Acquisition of suitable button & double acting cable system Will button fit in switch location on panel Measure button movement Dont have a reversing linkage, but like you could probably make one. Unlike you would take several hour/days (after acquiring materials) & include method & location of mounting. Mounting location may take several days to sort out, IF practical at all. I guess the position of the firewall hole, for the cable to Flap, would arrive as part of installation process - not happy with the idea of additional holes in firewall. I do have a flap that is capable of moving through 90 degrees (I will limit to Max 45 degrees) - a suitable mounting for the actuating mechanism to attach, would have to be fabricated Simpler (to me) to mount a two position reversing polarity switch (JayCar) Run a suitable 12V wire to power source (via fuse JayCar) and to Linear Actuator (have wire on hand) Mount Actuator (seeking advice on supplier of reliable unit) such that it will open & fully close Cowl Flap What's not to like??? Thanks for the "The Bullet Series 23 Cal. " suggestion from Firgelli - I had looked at these, unfortunately the closed length is around double what I require (see opening specifications). IF the Bullet is the only viable option, may have to reconsider existing mounting system. Firgelli used to do a much shorter/smaller range of Actuators (have one on my desk but seem to have dropped them). Firgelli (Canadian) likly have their actuators made in China & charge about x 10 the price of the very similar looking eBay offerings (see my opening comments). 😈

Thanks for all that RF Duty Cycle: Not sure how this translates in this context. The flap goes from fully closed/open in about 1-2 seconds. Current only flows between fully closed/open when limit switch activates. I thought a claimed 19 kg extension (pushing) force would be many times the effort required to open the flap ie a conservative capacity. Closing the flap (pulling force)will be assisted by air pressure, so much reduced effort required. Linear Actuator RS! so not able to perform any tests at the moment - do you know of a quality Linear Actuator supplier?😈

Why did I decide on a linear actuator to operate my Cowl Flap?? Perhaps at odds with the concept of mechanical/traditional operation of a small aircraft cowl the linear actuator present's as an easier/simpler way of the pilot opening/closing the flap. I can just hear you now - Naa! pull/push cable (traditional) must be the simplest. The traditional system would require; Another hole in my firewall For intuitive action (In for Close/Out for Open) a direction reversing cam would have to be made/purchased/mounted - not simple! A suitable location, on panel, for the Cowl Flap button would have t o be found (Sonex panel real estate in short supply). Reliability - Almost failure proof. Linear Actuator; Electrical wires to control/energise Actuator pass through existing firewall hole - no modifications. Two way toggle switch on instrument panel, Up for Close / Down for Open - small LED to one side of switch red for down/green for up. No issues with working out cam rotation/arc ratio to flap movement. Actuator extension movement must be matched to Flap movement - not hard. Linear Actuator - looks like a small hydraulic ram - is mounted in the exit air hole at one end & on cowl flap at other. System works very well, that is until Actuator stops working. Reliability - If I can find a suitable Actuator (hoping you can help) the system should be reasonably safe. Fail open - There is a small amount of extra drag/reduced/ engine systems may stay cooler than optimum performance - barely noticeable. Fail closed - There is the potential for increased engine system temperatures during Climb. The pilot may notice LED stayed green - abort TO. If in Climb should be able to manage this by reducing engine power, leaving prop pitch in Fine and returning for a landing. In the absence of a suitable Linear Actuator, I think I will move to a very simple system - Summer: Exit Ait Open / Winter: Exit Ait Choked (partially closed)

??????? Please explain 😈