EA 81 - Douglas Redrive

[Brian]

Thanks Butch, Nick, thats good advice. The dual throate carbys take a lot of playing around with to get all the jets clean so it will take perseverance and be carefull when using compressed air to blow out jets in the carby as other bits can go into orbit fairly easily !!!Good idea to trash the fuel [into the wifes car] as unleaded breaks down very quickly.Nick, I'm not sure but I reckon you need to brace the underside of the stab with a bit flat out from the keel to the underside of the stab. I have a Rosco machine and thats how he does his plus wires from the stab to the part in front of the rudder [whats that part called ???] Going to town early in the morning otherewise I would do a photo for you.I'm pleased other people have trouble finding things eg the butterfly,Brian

[NiqueNaque]

Brian,The stab comes from the underside of the keel so there is no way to brace off it. There is a strut attached to the fin that goes to the middle of the stab on an upturn about 90mm high, so this stops it from flapping up and down, but doesn't stop it pitching front to back. To overcome this I've wired both the front and back with stays, so they pull against each other, they are tensioned up as well. It appears to have stiffened it up considerably but the proof of this will be on the next run up to full power, probably Saturday morning.Steve,I've been able to read birdy's posts for all this time so the way you spell and type are not an issue, I know he just types like he speaks and you're the same, probably all thumbs on the keyboard.Did you kown taht if you sepll wrdos wtih the fnrot and bcak ltetres in palce and mix up all the mddile oens yuor biran wlil slitl raed it? As if nothing was wrong? Aamizng, eh!Thanks to you both.Cheers,Nick.

[NiqueNaque]

This will be brief,Yes:It flies;It's scary;It accelerates like never before, very punchy;It's very much more quiet;It's going to take quite a while to get used to, again.More installements after I get some sleep..Cheers,Nick.

[asra]

Well done Nick! []All the best, Ben

[NiqueNaque]

Ben,Thanks, appreciate it.Not forgetting the CTD that got me here in the first place either and everyone else who had a hand in it, ie, Wal Flaks, Jack Allan, the forum advisors and anybody who said anything about it.Issues I have yet to sort:Re-automating my responses - that is down to practice, practice, practice makes perfect.. in order to survive you have to learn things so they happen without thinking, if you have to think that will slow you down, the thought might come all too late if you aren't automated.Vibration - the engine is a little harsh and I suspect the prop is marginally out of balance, the next time I'm at the club I'll take the prop off and check the static balance. This is the most disconcerting as these vibrations will add deflection cycles to the air frame at a rapid rate, not good for gyro or Nicholas longevity, so must fix it quickly.Rotor shake - the stick circles at a slow pace in an orbit of about 1.5 inches diameter probably two every second. It is down to 35 cents of out of balance of one blade compared to the other on the new hub bar. I'll have to adjust the weights in the blade tips to fix this issue as these cyclics will also stress the air frame. I've adjusted the shims on the cotton reels so the teeter block is centered between the teeter posts, so that is not an issue. Tracking is near perfect with each blade sweeping within half an inch of the other at nearly all revs except the lowest ones.Rotor tach - needs recalibration - anybody know how to make these Liam brand cycle computers go into program mode for the rotor tach? I know you put in 1666 to make it read revs, in km/h. It seems every time I try to get into the entry screen for this it misses that bit or it skips to miles per hour. Grr..Performance:If you could have heard me over the motor and prop as I shot past you would have heard 'faaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaarrrrrrrr rrrrrrrrrrrrrrrrrrrrrrrrkkkkkkkkkkkkkkkkkkkkkkkk this goes like a scalded cat!.. 5hit, here comes the fence.. ooo, snowplough, snowplough, phew, glad the brakes work'The long hub bar with my old rotor blades is a dream to spin up, I only need to give it about 40 on the tach and it will hold, it is a bit of a stretch to get them started, but what I do is start the engine, establish that it will go, usually first or second shot, then kill engine and pad the blades up by hand whilst standing on the seat. Once revs are established I sit down and start the engine and pull the stick back, the wash off the prop sustains and/or accelerates the blades to about 60 ~ 70 in still air, then move off for a take off, they take a bit to get up to speed but I'm not pushing it because I still have to establish how they behave, need a good windy day for this.That is all for nowCheers,Nick

[NiqueNaque]

So,Last Sunday´s effort:Checked the problem with the rotors first up to see what the problem was, established by spinning the blades up into a moderate breeze what the problem was with the rotor shake. The new hub bar is a tad wider than the old one, this meant that the hub bar was floating on the teeter bolt spindles by 2 aluminium can skin thickensses on each side, about 1 mm in round figures, this was discovered by listening to what the rotor was doing without the noise of the engine, clunk, clunk, clunk with every half rev and most coincidentally every time the blades were square to the wind, what a surprise...So, out with the scissors to make up some shims from an alloy drink can, now the head is nice and firm between the teeter towers but it still teeters with freedom. The rotor is now quite good with an inch of front to back oscillation. It may require a check of the weight balance again but it was nowhere near as bad as it was the prior flight, I´ll get to this on the next visit.The next bothersome item is some vibration from the prop, it is shaking the air frame with full power and you can feel it hammering away in flight, too much of a risk for inducing fatigue in the frame so, off it came! I´ll check the balance and if I can, balance it, otherwise I´ll take it back to Jack for rework. I made sure it was the prop by running the engine without it on, smooth as, but not for long because there is no fan to cool the engine..Photos to follow,Cheers,Nick.

[Tim]

quote:Originally posted by NiqueNaqueI made sure it was the prop by running the engine without it on, smooth as,Nick, that dosen't prove that its the prop. The prop acts like a big flywheel and tries to resist any sudden changes in velocity (engine pulses). If the engine is "lumpy", it can be felt as a vibration with the prop on, but not with it off off. The heavier the prop, the worse it is. The heavier the flywheel on the engine, the better it is.How heavy is the flywheel on your engine?Tim McClure

[NiqueNaque]

Tim,Thanks, I´ll bear it in mind while I investigate.Cheers,Nick.

[NiqueNaque]

Another update for you...I rebalanced the prop, I found that it was 60g out at 50 mm on the chord wise direction, I had to skim about 1.5 to 2 mm off the leading edge of one blade and about the same off the tailing edge of the other. It was then about 20g out radially, which meant that I had to skim another .5 mm off one blade all over.How did I determine this?I made a prop balancing jig like one of the old static tyre balancers, it consisted of a bolt in a metal base plate, the bolt head was cut off and the end drilled down so there was a vee in the end left by an 8mm drill, the threaded end was screwed into the plate and lock nutted into position so it would not move. I then got a 3mm alloy plate and drilled it dead centre with a 1mm drill and then countersunk this with a 8mm drill, just. I bolted the prop onto the plate at the appropriate pcd with two bolts on the diametric centre. I then put a 1/8 ball bearing on the bolt top in the vee and then put the prop and plate on that, I put a bullseye level on top of that and then put some experimental weights on the prop to see how much I had to do to get it level, then took to the prop with a belt sander and a orbital sander. With persistant sanding and checking I got it to sit dead level according to the bullseye. Then to check I turned the bullseye several times into several positions, no change, then spun it slowly to see if it wandered, it didn't. I then bolted it onto the engine, perfect at 5000 ERPM or about 2400 PRPM.I left the rotors alone for a bit and after about 2 hrs flight time the stick wanders about plus/minus half an inch from side to side, two per rev shake, I think it would be down to the reflective tape I pulled off one blade but not the other, hence a very slight imbalance.I adjusted [increased] the trim spring pressure on the head and the stick pressures are very neutral for all but when you wind up the rotors, which is expected as they have no lift, but at about 120 RRPM it lightens up considerably, seems to be a finger and thumb grip to hold the joystick in flight, though a full grip is always recommended.The belt on the drive seems to favour the back of the sprockets, but I suspect it is still just a tad over tight and with heat it forces the belt to track to the rear.As I've not flown any other gyros apart from the two seater and the glider I asked Ross Bannerman to take it for a fly to see if he thought it was OK, after a bit I wondered if I would get it back. Ross being true to his word, was looking at everything and thankfully came back with a 'no vices, goes like a train report', which I am grateful to Ross for, thank you in the extreme. VSI rates were between 500 and 1000 fpm and it stops climbing at 30 kts, best rate of climb is 40kts at 5000 ERPM. He was upset with the absence of a pre rotator though, he said I could at least install a button...I had installed a new temp guage and found that at a supposed 210f it was actually 85c, so temp guages are not accurate, might use a K2 thermocouple next time.More to follow soon...Cheers,Nick.

[NiqueNaque]

Did I achieve the desired outcome?What were they? - More Power, more thrust and less noise, a close to CLT machine.Power - yes, we got that.. thank you Ozy WozThrust - I'm not complaining about a VSI of 1000 fpm, beats the hell out of 200.. thank you Ozy WozLess noise - killed that, I'm told it sounds like a Lancaster Bomber, I guess it might, but I've not heard a Lancaster Bomber, so I don't know but will take it on advisement as being so.... thank you Ozy WozCLT? - seems to be, but I didn't notice that the nose comes up when you apply power, it certainly comes down when you take it off.. the new stab is probably having a significant effect on its behaviour, maybe Ross can fill in the blanks here.Is the Oddysee Battery any good? - I was surprised when I walked back into the dealer I bought it off and he said they were over priced and over rated heaps of junk. I had to jump start mine on Saturday because I'd left the instruments on over a two week period, after about 2 hrs of charging at 8 amps [16 a/hours] it was able to start the engine even with some fiddling in between and three attempted starts from dead flat with charge on. On balance after that I'm sure one of the CBLA12-9 motorbike batteries I had before would have died on the spot, I think the Oddysees are a good battery.Where did I go wrong:The manifold is a bit of a disappointment, not in performance terms, but in terms that when it cools, it weeps coolant around the gasket onto the head, I suspect due to the steel / aluminium differences of expansion coefficients, an alloy manifold would work well in the same format, it would also help if I machined it off properly so it would sit dead level on the heads instead of relying on the gasket to make up the differences, so heavily.I pulled the R head off when I didn't need to [Investigating noise in engine - turned out to be spark sequence incorrect due to swapped leads on spark plugs], there was a film of oil in the coolant reservoir, but this didn't come back after I emptied it out so I believe the head gasket is tight, I have a kit and will just replace it to make damn sure, kits are cheap, fried egines aren't.Improvements:The coffee can filter assembly that I made up out of a HP9 air filter body and some alum sheet is cracking and falling apart, I'll replace that with some alloy sheet and a lower profile filter to stop the filter banging on the battery bracket brace.I'm going to move the radiator reserve up to a level higher than the rest of the cooling system and make it a bottom entry system so there is always some head of pressure on the cooling system, this helps to diagnose also if you have a cracked head or faulty gasket which is permitting gases to escape into the cooling system.Oil drain hose and reserve tank - I am thinking of getting some hydraulic hose and connecting into the sump drain point to provide a remote oil reserve and drainage point for ease of checking an maintenance. About a 1 litre steel tank with a sight glass and drain on it should be good for this - any ideas?Other than that I can't think of anything else, not at least until I go for another fly and have a look at it all over again.Am I happy with it?Yes, mostly. Though with my inexperience in flight I'm not overly confident with it, come to think of it I'm only just getting comfortable with it. I had a flight in it shortly before Ross did and thought it was good, the wind conditions were better, and now that it is quieter I can hear the variations in the wind hitting the prop and the air frame, which can be a scary thing, especially when you couldn't hear it before. Ross's report eased my concerns a little over how it performed, but I will take it easy for the next 10 hours, I'll be hammering my engine out techniques before I go for some cross country work.Rick's redrive appears to fit the bill as a viable arrangement for a subaru conversion, not only on my machine, Mal McKays and some other machines but also on his machine - which is much lighter than mine, as he is wrt me - the VSI could be a scary 1400 fpm. On its own it is smooth and very quiet. I have no issues with it so far, it is good.Cheers,Nick.

[NiqueNaque]

The continuing saga of the redrive.....heating problems were encountered with the radiator while running the engine at full power for sustained periods, typically with it tied down and doing 4800+ revs the engine would overheat.This was the original arrangement pre conversion:Image Insert: 66.19

[NiqueNaque]

You know,On thinking about my last post, I might just try the old radiator mounted on top of the redrive and see what it does, it could well be that the heat off the exhaust was compromising its ability to dispose of the heat, though I don't recall feeling the heat in front of the radiator, try the other one first before I get too excited.Cheers,Nicholas TomlinAlarmist - www.alarmist.com.au - we scare for you

[NiqueNaque]

And for today..Completed the new 'tall' radiator support bracket and installed it, topped it up and ran it, at 3k for 10 mins it didn't get past the blue - 115 f on the old richter scale.Stress test results to follow soon, once I fit up an expansion bottle and check the output, funny thing is that the radiator spilled more fluid when it stopped, not when it was running.Nicholas TomlinAlarmist - www.alarmist.com.au - we scare for you

[NiqueNaque]

And for today..Completed the new 'tall' radiator support bracket and installed it, topped it up and ran it, at 3k for 10 mins it didn't get past the blue - 115 f on the old richter scale.Stress test results to follow soon, once I fit up an expansion bottle and check the output, funny thing is that the radiator spilled more fluid when it stopped, not when it was running.Nicholas TomlinAlarmist - www.alarmist.com.au - we scare for you

[asra]

that spilling more fluid when stopped is quite common my toyota cilica does that too so does my Mom's little chevy and my dads GMC truckthe resovour bottle should only be about half full if I remember right other wize it will just throw it out .got any Pics of the instilation ?like to see it !Thanks !Bob......" Momm'a alwayse told me , Son the impossable is only a little bit Harder... and ya know I do believe She was RIGHT ! "