Avid # 846 is finally an aircraft

[birddog486 21]

This kit was bought 23 1/2 years ago and is finally ready to take to the sky with the FAA's blessing. Transition training in a Kitfox to satisfy the insurance man in one week and first flights in the Avid to follow.

 

Travis

 

[marksires 484]

congrats! looks great!

Mark

[Av8r3400 1179]

Congratulations, Travis!!  Lots of fun to come, now…  !!

 

Where in southern Wisconsin are you?

[SuberAvid 617]

Way to go!  That is persistence.  I'm sure you will have a blast in it.

[birddog486 21]

Well, I've only had it for just shy of three years but my dad bought it back in November of 1990. He worked on it off and on for a year and was able to get a couple wing ribs attached and it setting on the gear. He got busy with life and it got put away and sat in a shed for 20 years. After the last 10 years of me trying to pry it out of him finally in August of 2011 we were able to make a deal on it.

 

In 2 years 9 months and 1393 hrs. shes ready to fly.

 

Av8r3400 I'm down by Janeville

 

Travis

[High Country 69]

looks good, thats an interesting cowl, what is the bump on the top for. what power plant are you running. congrats on the build.

[birddog486 21]

Thanks guys,

 

the bumps in the cowl are there to give some clearance for the carbs. It has a 912ULS under the hood

[ChrisBolkan 130]

CONGRATS!

That thing is going to rip! Nice looking bird. Expect 90-100 MPH @ 3.5 GPH burn.

A couple questions:

Have you installed a doubler in the nose fork tube? Very important with bigger engine! You don't want it to buckle.

What is your empty CG? Did you have to put weight in the tail,the battery or both? Curious how much the plane weighs and how much weight you had to add if you did.

Temperature management may be an issue. If it is, restricting airflow into the two cheek holes will pull more flow through the oil and water radiators. Every 912 install I have seen in an Avid has needed some restriction in the cheek holes. In cold times restriction may be needed in front of the oil/water hole such as placing some tape over a portion of the radiators. I've even seen a very clever cowl flap in front of the radiators.

Would love to see some under cowl photos!

Once you get it dialed in the 912 makes the Avid the perfect plane. You are really going to enjoy it! It's a KEEPER!

Chris

[birddog486 21]

CONGRATS! Thanks Chris

That thing is going to rip! Nice looking bird. Expect 90-100 MPH @ 3.5 GPH burn.

A couple questions:

Have you installed a doubler in the nose fork tube? Very important with bigger engine! You don't want it to buckle. Yes, I have a doubler in the nose tube.

What is your empty CG? Did you have to put weight in the tail,the battery or both? Curious how much the plane weighs and how much weight you had to add if you did. The plane empty weight came in at 667# and an empty cg at 12.145     The most FWD is 13.039 and the cg for the test flight will be 13.192  The battery and ELT are in the tail, theres no additional weight added.

Temperature management may be an issue. If it is, restricting airflow into the two cheek holes will pull more flow through the oil and water radiators. Every 912 install I have seen in an Avid has needed some restriction in the cheek holes. In cold times restriction may be needed in front of the oil/water hole such as placing some tape over a portion of the radiators. I've even seen a very clever cowl flap in front of the radiators. Thanks for the info, This has a coolant thermostat and I'm not running an oil cooler.

Would love to see some under cowl photos!

Once you get it dialed in the 912 makes the Avid the perfect plane. You are really going to enjoy it! It's a KEEPER!

Chris

 

[EDMO 1078]

Travis,

       Real nice bird - Hope you have many enjoyable hours in it.

EDMO

[dynomike 91]

congratulations,great looking plane ,let us know how it does

[Av8r3400 1179]

Where's your oil tank?

[birddog486 21]

Where's your oil tank?

The oil tank is under the baggage compartment.

 

[Av8r3400 1179]

Oh. Okay.

For you it will be extremely critical that you monitor oil pressure very closely. I had a friend with that setup in his mk IV. It nearly cost him an engine due to the oil pumps inability to draw through the long lines. The oil pump cavitated badly eventually causing it to fail. Luckily he was on the ground when it did.

[BryceKat 125]

Congratulations!

[ChrisBolkan 130]

Nice install. Well thought out with regard to weight and balance with the battery way in back. The Avid owners I know running 912's have trouble getting oil warm enough. I haven't decided on installing the cooler in mine or not. Will be interesting to see how your temps run.

One comment....first with the caveat that I have no first hand experience only hearsay so take this with a grain of salt, but definitely research more before flying!!!! From what I understand Avid and maybe kitfox went through a very short phase where the install instructions had the oil tank mounted in the baggage area. Great idea as it put some weight back to help with W@B and got it out of the crowded engine compartment. However, my understanding is that there were some incidents with oil starvation or hydraulic lock or something due to long lines and oil tank position relative to engine. Rotax has a tight range where they want the oil tank relative to the engine (height wise) and placing the tank in the back violates that range on climb out and steep decent. Also the Rotax uses crank case blow by to pump the oil to the tank so there are serious issues to consider with tank placement.

One of my friends packed his into the engine compartment on the left side if you are facing the plane. That's where mine is. Another friend placed his inside the firewall on the passenger side. Both of these locations are good because of the close proximity and proper height of the tank relative to the engine.

Anyway, I do know that no one mounts the tank in the baggage area any more. I wanted to do that and I was told NO NO NO! So please research this more before you take to the air.

Otherwise Awesome install!

Chris

[birddog486 21]

Thanks for the heads up on the oil tank. I did quite a bit of research on putting it back there and I did here a story or two about problems that were thought to have been caused by the tank being that far away. However I think there's more to the story as far as what caused the problems with those installs. In the Rotax installation manual there is a maximum & minimum height, distance and tubing size recomendation and this install is within the specs given by Rotax so I'm hoping I dont need to make any changes but time will tell.

 

Before I made up my mind on the placement of the tank I was able to get in touch with a handfull of 912 builders that have the oil tank under the baggage compartment and there are a couple that are over 1000 hrs with this setup and have had no problems.

 

I do have an EIS thats setup with the flashing red light so if a problem presents itself it wont be missed until it's to late. As of now this install has about 2 hrs running on it and It has no problem with oil pressure holding in the 70's when its up to temp. The warmest I've seen the oil on the ground is 150 at 4000rpm for an extended amount of time so I'm curious what kind of temps I'll be getting when she's in the air.

 

Travis

[ChrisBolkan 130]

Glad you've researched it and have solid information! Can't wait to see your comments on that rocket ship when it takes to the air. My friends with 912 installs in Avids are 80hp and they are amazing. 100hp should run like a scalded cat. My Fat Avid has the 100 HP engine, but I haven't flown it yet AND it is a larger plane so will not perform like yours!

[ChrisBolkan 130]

Oh........Power to weight ratio in your plane will be very similar to my Magnum with 150HP engine. It was crazy impressive! You won't be disappointed!

[Av8r3400 1179]

I know of no Kitfox setup that ever put the 912 oil tank behind the seat.  Only the Avid.  The Kitfox 1-4 FWF puts the tank (too) high and behind the engine, requiring the reversal of the intake manifolds.  Birddog, what are the specs for distance on the oil lines?  I never knew there was a spec for that.

 

I hope you can get more than 150º on the oil once you are flying.  You may need to actually insulate the oil lines to keep heat in.

 

One of the theories why my friend's setup failed is that he was never able to get the oil up to temperature.  The thick cold oil would not pump easily and bubbles formed in the pump causing cavitation and eventual erosion on the impeller which finally failed.

 

He has since converted to a newer Airdale built motor mount which puts the tank under the cowl on the right side of the engine.  No more problems.

[wypaul 448]

Cold oil probably won't be an issue, mine runs 230-260F with the same setup. Planning on an oil cooler when I decide where to put it.

[birddog486 21]

I know of no Kitfox setup that ever put the 912 oil tank behind the seat.  Only the Avid.  The Kitfox 1-4 FWF puts the tank (too) high and behind the engine, requiring the reversal of the intake manifolds.  Birddog, what are the specs for distance on the oil lines?  I never knew there was a spec for that.

 

I hope you can get more than 150º on the oil once you are flying.  You may need to actually insulate the oil lines to keep heat in.

 

One of the theories why my friend's setup failed is that he was never able to get the oil up to temperature.  The thick cold oil would not pump easily and bubbles formed in the pump causing cavitation and eventual erosion on the impeller which finally failed.

 

He has since converted to a newer Airdale built motor mount which puts the tank under the cowl on the right side of the engine.  No more problems.

 

In the May 2007 Rotax 912 installation manual (page 71) the max distance from engine to oil tank is 10 feet using a 13mm line or roughtly 1/2"