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Mendlerr added a post in a topic Prop Problems 31 May 2013

Weird, my dad got caught in a downdraft a few miles away near Grandfather Mountain (ELV 5,945FT) where I actually live. This was about 15 years ago before he passed. He was in a Piper Seneca II (light twin with 2 IO-550's) he almost did not make it out, it pushed the airplane down fast but fotunately he got away from it by shear luck.

That would be very strange if we were in a downdraft but I suppose it's not unheard of. Today was calm, dead calm, and hot, almost 93 degrees on the tarmac, at about 3pm the windsock started whipping around doing 180's at about 10-15kts. It's been doing this for a few days now and it's kind of strange. Severe wind changes and 10-25kts of wind out of nowhere

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akflyer added a post in a topic Rotax 582 Greyhead Problem 31 May 2013

Second thought.... is there any signs of galling in the carb barrel?? the way you were desbribing it on the phone, it seems that there is still tension on the carb barrel when you pull the throttle back to idle.. that can really only come from the infight mixture cable...

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akflyer added a post in a topic Rotax 582 Greyhead Problem 31 May 2013

The only way that can happen is if the inflight mixture cables are dragging and not letting the pistons in the carb come back down freely. You already safety wired the cables to the top of the carbs now, but I would really check those infight cables and make sure they are moving freely inside the housing! It does not take much of a "pinch" in those cables to mess up the whole works.

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akflyer added a post in a topic Prop Problems 31 May 2013

The original smooth flanged prop hubs from IVO had an issue with the 3:1 gears and what they thought was some sort or harmonics that caused some movement in the blade roots. The new knerled flange faces bite into the blades and I do not know of any issues since then. I run 3:1 gears and the ultralight 3 blade and have never seen the SS tape crack to show blade movement. I even replaced the SS tape on the roots with aluminum tape and they never cracked. almost 400 hrs now and I have not had any issues with blade movement on the ultralight prop at 3:1

I have done a few test flights on turbine RC jets. Lots of fun, but it does get spendy in a hurry! If I had the money right now that I had in RC planes, I could go buy a nice 180 on new floats oh well, a guy can never have too many hobbies right??

I am going to now put money on the down draft theory.. if the engine never lost power, the chances of "stalling" a blade are damn near zero. The chances of a down draft and weird weather phenomenon... alot higher!

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Mendlerr added a post in a topic More power than a 582 31 May 2013

On the topic of the 670, it is alive and well. Over 70 flying from what I have been told. Rotax Rick in FL is apparently the authority on the 670 and has redesigned the engine using cageless lower bearings which greatly increases the reliability along with a piston and rod upgrade

The UL670 mount to the 582 mount, uses the 582 ignition and is only 3/4 of an inch taller then the 582 due to the RAVE valve. The weight is also the same on the newer versions of the 670.

If you send in a good rebuildable 582, the cost of a brand new 670 (all new parts) is only $3,350. The new exhaust is around $675. Without the exhaust your not going to make any more power then your 582, but with the exhaust the power increases to 89HP at 6,900 RPM's which is redline for the detuned UL670.

For takeoff (Rotax Rick recommends Warp Drive prop on the UL670) set your static RPM to 6,500-6,600, this will give you around 6,900 takeoff and full 89HP.

When your up in the air throttle back between 5,500 and 5,900. The advantage is with the extra power you can add alot of pitch to your prop and be at the same RPM as the 582, therefore you create much more thrust and your cruise will increase. At 5,500 RPM's the 670 burns around 4 Gallons per hour, and it burns around 4.5 gallon per hour at 5,900 RPM. The 670 has no problem turning that RPM as it was originally designed for 7,000+RPM's

The TBO time of the new 670 is 450 hours instead of 300. This is due to the lower fuel burn, Rotax bases their TBO time on the time it takes to burn 1,500 gallons of fuel, Rotax Rick uses this same theory.

This is all information I copied from an email conversation with Rotax Rick. Seems like it's a good deal if you want to stick with the 2-Stroke.

Also a complete overhaul of the UL670 is $1,175 and the GreenSky HACman kit will not work with it for some reason, they had bad results.

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lv2plyguitar added a post in a topic Rotax 582 Greyhead Problem 31 May 2013

The part I am talking about is the brass cup on top of the carb that the throttle cable rest in. The throttle cable, even with all slack taken out comes out of the top and rests on the lip of the brass cup.

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Russ. added a post in a topic Rotax 582 Greyhead Problem 31 May 2013

When you say carb. boots are you referring to the carb. to eng. boot or the throttle cable boot to the top of the carb? I had problem with the throttle boots and safety wired them.

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Mendlerr added a post in a topic Prop Problems 31 May 2013

I just called IVO to ask why I cannot use the Ultralight IFA on the 3:1 ratio gearbox.

They said I could, but there is not guarentee it will be safe.

The problem lies in the max torque value of the ultralight hub, when the 3:1 gearbox winds up it creates enough inertia to overcome the max torque on the bolts of the ultralight hub, this causes the blade roots to twist and flex. It hasn't happened to all of them but it has happened to atleast one, so they cannot recommend the ultralight prop on the high ratio gearboxes, even the 3.47. If the root twist too much then the blade will seperate (I'm assuming) just like the GSC props if they are overtorqued. He did not get into details of actual failures but said they have happened.

He also told me that the Medium 2 Blade should produce the same climb, if not better, then the largest ultralight 3-blade prop but he could not give me exact numbers. A 72-74" 2-Blade Medium would be my best match, according to IVO. He actually recommended I switch to a 3.47 gearbox and a 66-68" 3-Blade Medium for best performance all around but we are talking big money then. To turn the large medium smoothly requires an RK400 clutch which adds roughly $600 to the already high price.

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Mendlerr added a post in a topic Prop Problems 31 May 2013

From what I hear this is extremely unusual but believe me, I started the engine and it took a second for the Tiny Tach to catch up but it was pretty accurate, I was expecting a huge difference. I ran the engine at 3/4/5/6k RPM's then WOT. I came back, shut down and let it cool down, went out and did it again. Same results!

Then I got to watch a $20,000 RC Twin Turbine Jet smack the runway at about 200MPH. That was fun, I feel bad for the fellow flying it, it was his first flight with a huge 2 year long project to build this thing but man, he had more pieces on the runway then when he bought the kit. It came down vertical from 300ft or so at full throttle on a couple of $5,000 jet engines. You could actually here the engines hit the nose cone on impact and you could hear them flying apart as they spooled down.

Oh and we maintained full 6,500-6,600RPM throughout the whole takeoff. We just could not climb or accelerate. There is no doubt that where my airplane is based is notorious for hard downdrafts and crazy ridge wind, but there were 5 people watching us on the ground and they did not note anything unusual. About 13kt winds coming from the N and NW.

I will definitely install new plugs and gap them to .016 if you feel that will help. I can understand why it would.

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akflyer added a post in a topic Prop Problems 31 May 2013

gap the plugs at .016 max. The ducati ignition does not like the larger gaps. If you start at .018 and they wear a little bit, your asking for too much out of the ignition system.

I still never saw an answer to... did you loose power and RPM when it started sinking or did you just start sinking with the engine cranking out full RPM

You must have the ONE AND ONLY rotax tach that is that accurate. Pull it out and send it to a museum to preserve. Hell you may even be eligible for a guinness world record with that one

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akflyer added a post in a topic Tailwheel 31 May 2013

The wide bungee gear is fine.. the gear that everyone refers to as the "bush gear" is the "cub style" that uses a die spring on the cabane vee. The spring does not allow for enough travel so you bounce it one good one and it bottoms out, goes metal to metal and it tweeks the fuse sides and bottom stringers...

So the Avid "wide gear" and the grove gear are the two main options right now. The Avid Wide gear is 3 or 4" taller as well as 10 or 11" wider but still use's bungees. If you go to the wide gear, you need to put the wood or metal triangles in the seat truss openings or you will fold up the seat truss due to having to use heavier bungees and more wrapps because of the increased moment arm on the end of the gear.

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Mendlerr added a post in a topic Prop Problems 31 May 2013

So here are my results, 1 hour of engine running and the Rotax Tach and the Tiny Tach were only 50 RPM's off throughout the powerband except for 5,000 RPM's, there was about a 100RPM discrepancy at 5k. At full throttle both tachs read around 6,200. So it's not too horribly off, you can hardly read 50RPMs on the Rotax Tach anyway.

EGT's still hold at 1,050 and 1,075 at WOT and 6,200 RPM's. I did notice that at certain RPM's in the power band the two EGT's temp difference gets a little large, close to 75 degrees off but it is only momentary, then they go back to being 25 degrees off or so.

I pulled the spark plugs and they look fine. A little ashy light grey but from what I understand that is perfect. 1 of the plugs had a small amount of buildup but nothing to be concerned about. FYI they are NGK part # BR8ES and they are gapped to about .018

I also replaced the fuel regulator, as I noticed a very small amount of fuel leaking from the regulator when the engine was warm. The seal was expanding a little and allowing a small amount of fuel to escape from the adjustment knob, not enough to affect flight though. Just good measure to replace it.

There is a an inline fuel filter behind the seats, it has some trash in it. From what I can tell it is insignificant but I suppose there could be something plugging it up. When I burn the fuel out of the wing tank I will replace the filter, they have them at the local O'Reilly's.

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EDMO added a post in a topic Amazing Spitfire Pilot interview 31 May 2013

That is Priceless Joey - Thanks so much for posting it.
EDMO

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herman pahls added a post in a topic Tailwheel 31 May 2013

SuberAvid
You responded with "Wide bungee gear fan" and Leni said the after market bush gears have had failures.
So who makes the gear you suggest?
Thanks Herman

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C5Engineer added a post in a topic HOME DEPOT PROJECT AIRPLANE - U TUBE 31 May 2013

Where is the video of it flying? I guess as long as your wheels leave the ground an inch technically your flying right?

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lv2plyguitar added a topic in Avidfoxflyers General Hangar 31 May 2013

Rotax 582 Greyhead Problem

I had previously posted on this forum an issue with my engine inadvertently reving up 600 rpms without giving it throttle. Last night I found a strange problem that I do not know how to deal with.

The same problem started again. The engine reved from idle 2000 rpm to 2600 rpm. After a minute it reved from 2600 rpm to 3200. I pulled the cowling and found the strangest thing going on. The carb piston is raising on its own and causing the cable housing on top of the carb to set on top of the brass seat therefore not letting the carb piston to go back down. When one carb does it the rpm goes up 600 rpm. When both do it the rpm goes up to 3200.

Both carb boots are tight and brand new. The egts run normal as well as the engine temp. It seems to run rough at idle. I am wondering if the jerking action of the engine would create enough force to cause the carb piston to raise up and down on its own.

Help

4 replies
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C5Engineer added a topic in Avidfoxflyers General Hangar 31 May 2013

Amazing Spitfire Pilot interview

About 15 min but worth every minute! I love this type of stuff!

1 reply
568 views

akflyer added a post in a topic Prop Problems 31 May 2013

Make sure you wrap the lead around BOTH plug wires on the same cylinder so you can do a mag check. Now that you know you have it, it will be easy to compare readings and see what your RPM actually is. If the rotax tach is even close I will be AMAZED!

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Mendlerr added a post in a topic Prop Problems 31 May 2013

Okay guys I feel real F***** stupid.

I took another look at my engine and the panel and I noticed a red wire wrapped around one of the spark plug wires. I immediately realized it was a digital tach. So I started looking around and I found a freakin Tiny Tach already installed. It's underneath my panel facing down, I will have to unscrew it and move it to actually be able to read it. It's definitely not accessible but I do have it. I can't believe I didn't find it earlier. It looks like a relay or something and why they would face it upside down and behind the dash I do not know

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Av8r3400 added a post in a topic More power than a 582 31 May 2013

There's a couple of guys over on TeamKitfox that have 912 powered early Kitfoxes.

A full install ready to run would weigh near 160 pounds. The difference between the 80 and 100 weight is minimal, maybe 5 pounds?

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herman pahls added a post in a topic More power than a 582 31 May 2013

Av8r3400
You emphasized the light weight of the 912.
Any idea the weight difference between the 912 and a 582?
My 582 has the inflight adjust ivo, clutch, Hackman , c box which all ad weight.
I would go with a 912 if my model 2 could tolerate the added weight.
I already add 8 pounds of lead to the tail if I use the 29" air streaks.
Years ago some one in Utah or Idaho said that he powered his model 1 Kitfox with a 912 and had to add some tail weight.
Does anyone know who that may be ?
Do the 80 and 100 hp 912's weigh the same?
My model 2 has a never exceed speed of 100 mph and a gross weight of 950.
With the bush wheels this Kitfox is already a single place airplane so why not go with a 912 if the CG works out.
Thanks Herman