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ENGINE ARRIVES!


Gulfstream1
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Knock at the door this morning ....... white van man (brown actually) - with 1 x large heavy box!

The Aixro XR50 has arrived.

For those who have not followed my previous notes - this is the "platform" which I am going to use to [re] - design & build a +/- 12kg - 13kg (?) alternative rotary based PPG power plant with over winter.

One of the major aspects to this project will be the binning of the standard water cooled combustion chamber/block and replacing it with a CAD/CAM designed air-cooled block - the water cooled block/chamber constituting a significant portion of the engines' "out of the box" standard mass/weight - and to that end, I have "found" a engineering uni-undergrade at Bristol Uni, who for a reasonable "grant" towards his uni upkeep (read as: week-end piss-ups I guess!) will be doing the thermo-dynamic calc's re: conversion from water to air cooling (i.e. size of/position of/lenth of/placement .... blah blah, blah blah .... of the fins)

So - yes, the original combustion chamber block is out and is going to be replaced with an air-cooled alternative. What problems, and how complicated this aspect of the projects turns out to be is yet to be established, but its going to be one extreme or the other, if my thoughts about this are correct i.e. it's going to be straightforward,or its going to be a complete nightmare.

I am banking on UAV ENGINES experience translating across to my project in the sense that they have a successful range of high powered rotary engines (for UAV's) that are air-cooled. Noting that UAV ENGINE companys' "time to overhaul" time frame is circa 150 hrs, I have yet to establish how this will impact on the idea's I have, and just how that can be deal't with, as I have little doubt (and this is an educated guess on my part -largerly), that the "time to overhaul" figure they have is largerly tied up with the fact that the block is air-cooled as opposed to been water cooled. Still, I don't believe it's an insurmoutable probelm - even if we still get a overhaul time of say 300 - 400 flying hrs because of air-cooling, so what - i think that will be aceptable.

For those interested in UAV ENGINES rotary power plant check out:

www.uavenginesltd.co.uk/index.php?id=397 .... and check out that power/weight figure - 38hp @ 10kg's (!!!)

Yes - thermodynamics, while reataining nice power/torque/rpm characteristics are going to be a big part of the project overall. Anyone who has experience on this subject - please share with me.

In addition to this a major rebuild of the engine will take place to bin a lot of the standard components which will not be needed in a PPG formatted engine, as well as redesign of some existing components that will have to stay on, like the flywheel/charging system which I believe can be lightened substantialy by way of redesign and replacement with a custom machined and made unit.

I have had a nice chunck of AlBMet lying in the attic for years now, and am keen to use this to make whatever parts it can be used for, to remake and replace re-designed parts and components with.

AlBeMet is a fantastic metal maxtrix compound based on aluminium and beryllium - for more info on this stuff check out Brush Wellmans' website at: www.berylliumproducts.com

For the Aixro XR50 spec's (out the box) - see: www.woelfle-engineering.com

Fuel injection intergrated with 3 dimensional mapping of the fuel/air mixture for all altitudes will be a big part of the project - based around a MOTEC M2R ECU.

See: www.motec.com.au/m2r/m2roverview/ for the details on this rotary engine ECU box of tricks!

I have however decided not to bother with supercharging. While s/charging certainly offers big plus points at high altitude, the idea behind this project is come up with a solid relaible alternative lightweight powerplant. In its normally aspirated form the XR50 chucks out more power than just about any exsisting PPG power plant option as it is, and as such s/charging would not in any event offer any real world useable advantage untill one started crusing around at 10k ASL, or similar high altitudes ... and just what proportion of flying time to PPG drivers spend up at those sorts of altitudes .....?

Exactly - so supercharging is not on the cards - this will be kept as a normally aspirated ic engine.

..... anyhow with the permission of PARAMOTOR.ORG's "management" perhaps this is a thread that could be "pinned" to the start of the Paramotor section or even the start page on the Forum section, as something for folk to follow over the winter -

and I'll fill it with design notes/descriptions, video clips and digital photo' as the project progresses - and invite interested members to post comments, ask questions, share ideas ....... or have a laugh at what is no doubt will be a bit of a comedy in places.

I expect to get the project up & running towards the end of this month - in the meantime, if anyone has any questions or wants to make any comments - I'm all ears, fire away.

Aixro-XR50.jpg.426d7761a64b52928aa4e271d

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Hi Gulfstream,

Just a thought if you could get the software to give you an

economy/performance option just by fliking a switch. I dont know how the

rotary engine fires but if its like a twostroke every compression you could have

it like that for take of ect then cut to every second compression to just cruise

about using the injectors to do that would make it much more economical on

fuel.

Dont know how possiable that is as no one seemed to do it with a twostroke .

Cheers Col...

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Hi Gulfstream,

Just a thought if you could get the software to give you an

economy/performance option just by fliking a switch. I dont know how the

rotary engine fires but if its like a twostroke every compression you could have

it like that for take of ect then cut to every second compression to just cruise

about using the injectors to do that would make it much more economical on

fuel.

Dont know how possiable that is as no one seemed to do it with a twostroke .

Cheers Col...

WeeSplat

Actually, rotaries can be built as both 2 stroke or 4 stroke type engines - I'm no expert on the theory, but off the top ofmy head my guess is that running one type as the other type would be difficult - I'm trying to picture the fuel/air mixture inlet/outlet arrangement, and I think that there are going to be substantial differences between the 2 - so much so that even if it were possible, there would be all sorts of problems with the power/rpm curves - not disimilar in many respects to thes edifferences between 2 and 4 stroke conventional internal combustion engines.

Still .. at this stage I am discounting nothing - everything shared with me as an idea is going to be chased up.

Thank you for the idea.

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I expect to get the project up & running towards the end of this month - in the meantime, if anyone has any questions or wants to make any comments - I'm all ears, fire away.
Looks like you have a great winter project ahead of you Chris !

Are you planning to keep a blog to document and share your progress ?

Andy

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I don't understand why you don't leave it water cooled? it works, tried n tested. is it a weight issue? I tinker with 70's yam fs1e's, we are always trying to get more power, some of the guys have converted them to water cooled cylinders with great sucsess and cooling better than air as overheating is a big problem with these bikes, i would be inclined to keep this and mod it if it is a weight issue

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check out that power/weight figure - 38hp @ 10kg's

AlBeMet is a fantastic metal maxtrix compound based on aluminium and beryllium -

Fantastic project, I look forward to following your progress.

My guess is the UAV time to overhaul is closely linked with the 38hp figure, so less power from yours should give a longer time. As for air cooling Fresh Breeze fit larger modified cylinder heads with bigger fins on for both the solo and monster engines as a pointer.

A small caution with the metal matrix, if by sawing or otherwise the beryllium forms a dust be very scrupulous about breathing protection as beryllium dust is toxic. CORRECTION. It's beryllium oxide dust that is toxic, maybe not straight beryllium.

Good luck,

Alan

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I'll respond to all comments in one posting:

Yes - this project is going to be blogged and posted up online in detail for folk to follow - the intention is to post up progress as I make it - my thinking, the decisions I take, the actual work as it progresses, along with digital photos (maybe some video clips where they serve to communicate some or other aspect), and lastly the clac's and theory behind decisions (e.g. CAD program's used and how the program was used to resolve issues e.g. heat dissipation, how fin sizes are calculated in size, shape and surface area, to replace water cooling) ... it's all going online for folk to follow, and also for folk to comment on and critisize.

COBRA - why not leave it water cooled? Amongst other objectives, is the desire to reduce mass and complication. Water cooling adds both mass and mechanical complexity - neither are excessive, but in a PPG application both mass and complication are characteristics that one seeks to reduce.

Mass - for obivious reasons (the lighter the gross mass carried the further the range, the less fuel is used, the easier the PPG is to fly with, and the greater the spare mass there is avalible to carry something else e.g. more fuel, extra hardware such as a camera or other recording device etc etc..)

Complexity - water cooling adds mass. I linked the opening post in this thread with another company thats makes lightweight rotaries (i.e. UAV engines) - its through air-cooling that they have managed to get the mass of their rotary down to what it is (i.e. 10.0 kg's). My intial feeling is that around 30% of the "out-of-the-box" mass can be got rid of from this engine -a large part of which will be associated with water cooling setup/components. But weight/mass aside - water cooling adds complexity and moving parts. Getting rid of them gets rid of parts, and leaves less to potentialy go wrong. Of course there is a possible trade-off (still to be established): less power output so that their is less heat produced and less to be dissipated. That said, using UAV Engines 741 model as a comparartive example, it appears that plenty plenty power can still be realised (+/- 40hp on the conservative side) with air-cooling

My take on it - conversion to air-cooling enhances characteristics that everyone seeks in selecting a PPG motor.

ALAN-K - yup, I am aware of the issues surrounding the machining of Berylium based matrix's - if I did use any of the stuff on the PPG it would have to be sent off to be machined by a specialist - the dust is dangerous. While I do have ideas of making more of these motors if it works out, it would be unlikely that AlBeMet components would be an option on retailed examples - if only because of cost - the stuff is hugely expensive (10 x, 20 x or more expensive than the best air/space spec'd aluminium alloy e.g. 7075). The piece I have is a one off piece I was lucky to get hold of. I had no plan in mind when I got it. It was a commercial sample that was produced for a friend of mine who runs an aero-space company in the UK (the main market for this matrix). When finished with it (they decided that it was not suitable in the rf aplication that was intended for) he was going to put it onto eBay. I asked him how much he hoped to get - and in a moment of madness, offerd him the same amount (which was about the same as what a block of certified 7075 T6 would have cost) - I mean, how many folk can say they have 36" x 14" x 18" block of AlBeMet in their attic. Trying to find out if it could be used to make the combustion block from (???) ... that would save some weight and a bit ... and then again, I may not use it all.

The TBO and it's relationship with the hp output that you cite in respect of the 741 engine, are defineatly related - but I also have a sneaky feeling that the combustion chamber coating is a limiting factor as well inthose engines. I just happen to know who coats the chamber (it's Apicote in Gloucestershire) and what coating is used. Coating any combsution chamber is a balance between wear resistance and heat dissipation - the 2 contra-indicate each other: the harder the coating (and many of these hi-tech cylinder coatings are ceramic in nature) the greater is it's resistance to heat transfer, and while the more heat you have the more efficient the rotary engine works, the problem is cast and forged alloy rotary chambers can only withstand a certain amount of heat (thats just the nature of aluminium - gets to hot it looses it's strength characteristics) So, I'm looking into chamber coating alternative's. In a one off, perhapos some exotic expensive coating can be justified - I don;t know, and then again, if the AlBeMet was used i don't know if any of the exotic coatings can be applied to AlBeMet - I don't even know if AlBeMet can be used as a combustion chamber. There are lots of issues that have to be worked through still .....

NORMAN - yes, it may be a grat idea to have this set up as a seperate thread and share the progress with those interested. Then again, if its something that was to work and turned out to have commercial viability, maybe detailing it all ain't a great idea - I'd defineatly want to hold back some detail. Anyhow, thats another story - running the progress is in principal I great idea

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  • 2 weeks later...
  • 3 weeks later...
  • 5 months later...

Is it time to stop this thread from being a sticky? Nothing has happened in 6 months now. If anything happens it could be brought baack to life but in the meantime cane we let it slip down the list so it doesn't mask active discussions.

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  • 10 months later...

Surely a detuned version with say 25-30hp would be more than adiquate for a paramotor engine ? Then the working life could be extended and air cooling would be a viable option. Something like the Wolfe XR50 in aircooled form with a bit of lightening would be ideal. Also I can't see to many problems with the likes of Nikasil on alloy (I believe it's something similar). What would be ideal is to get someone to machine a cylinder from aluminium and use someone elses rotor/crank. I suppose if you were to do without a clutch you could use a very lightweight flywheel.

I've had a similar idea myself for years but cost has been an issue. There is certainly much potential out there. I did look at the Parajet but it's basicly a wlofe engine (despite them saying it's their own) And it's very overweight. I recon what's planned here is very doable

I was also looking at the new batteries from 123 systems (read dewalt xrp). Electric is almost a viable option now.

The future is looking good.

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Is it time to stop this thread from being a sticky? Nothing has happened in 6 months now. If anything happens it could be brought baack to life but in the meantime cane we let it slip down the list so it doesn't mask active discussions.

Done.

SW :D

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