Marty d's CH-701 build log

[Marty_d]

2 hours ago, eightyknots said:

No e-props propeller?

I decided not to.  They sound great but they are soooo narrow and light - I worry about long term strength.  Probably not going to be a problem but in terms of aircraft, if nothing else, I'm a bit conservative.

[Marty_d]

Solved the axle problem - good suggestion @fallowdeer, I bought a Savannah Tundra axle from Peter at Aerokits which is exactly the right size for the big Zenith fork.  I think the bigger donuts look good and it's raised the plane 110mm - prop centreline to ground is now 1150mm, which is 50 more than the plans.  

 

[Blueadventures]

Hi Marty  KItplanes have an article on how to make silicone fire wall boots.  Out todays email alerts, do you get Kitplanes emails?  Cheers

 

[Marty_d]

22 hours ago, Blueadventures said:

Hi Marty  KItplanes have an article on how to make silicone fire wall boots.  Out todays email alerts, do you get Kitplanes emails?  Cheers

 

Hi Mike,

 

I don't, but found it on the web.  https://www.kitplanes.com/diy-firewall-boots/ 

 

Thanks!  Good idea.

[Phillip King]

 Hi Marty

I used Land Rover high low gear leaver boots for my fire wall boots 

cheers Phil 

[Marty_d]

Finally opened my birthday present!

 

 

[nomadpete]

Wow!

Lucky man!

Happy Birthday!

 

 

Gee, that would look great on the front of an aeroplane.

[Marty_d]

30 minutes ago, nomadpete said:

Wow!

Lucky man!

Happy Birthday!

 

 

Gee, that would look great on the front of an aeroplane.

It's back in the box for a while Peter... no point putting it on until I'm ready to adjust it, it'd just suffer hangar rash.

I had to keep them away from the kids... they took one look at the blades and yelled "light sabre practice!!".  Yeah, nah.

[IBob]

Very nice, Marty: I've certainly been very happy with mine.

I made a simple but effective laser pointer that hooks on a blade and projects onto the floor, used that to pitch all blades identical, have enjoyed super smooth running from day one.

[Marty_d]

3 hours ago, IBob said:

Very nice, Marty: I've certainly been very happy with mine.

I made a simple but effective laser pointer that hooks on a blade and projects onto the floor, used that to pitch all blades identical, have enjoyed super smooth running from day one.

Excellent idea Bob.  The instructions talk about a wooden stick but the laser pointer sounds far easier.

[IBob]

Yep, I found the stick very imprecise.

I can't remember the exact number, but on the Sav with a blade horizontal, each degree of pitch is about 20mm on the floor, so you really can set up very accurately....though you do also have to check tracking (any difference in how far forward/back each blade tip is), as that can throw this method out.

 

I'm pretty comfortable with the way I do it; however I'm sure there are inclinometers now available that would do just as good a job.

[Thruster88]

The clinometer app on my phone is very accurate and repeatable. Just as good as the proper one at work.

[Blueadventures]

3 hours ago, Marty_d said:

Excellent idea Bob.  The instructions talk about a wooden stick but the laser pointer sounds far easier.

This image shows a laser pointer onto the hangar floor.  2 & 3 were very close and 1 was way out (1 degree).  After adjustment 1 was between 2 & 3 so happy with that.   Your can also measure the distance from blade to floor measure the gap between the dots and calculate the angle using that one angle is 90*. 

Edited April 13, 2022 by Blueadventures

[Marty_d]

How do you decide what angle to set the blades at?  I've heard that WOT on the 912 is meant to be 5800 (I think).

[Blueadventures]

14 minutes ago, Marty_d said:

How do you decide what angle to set the blades at?  I've heard that WOT on the 912 is meant to be 5800 (I think).

This bolly on Lightwing is 24* .   He will now fly it and maybe readjust depending on rpm etc.

 

For yours as bolly manual says or ask on forum for similar installations on 701's.   Or could set at say 24*   and see what performance you get tied down.  Bolly will say approximately what change a one degree course or fine adjustment will make to rpm.  I have this written in my Skyfox notes from years ago when I had a bolly on my taildragger.  Details not handy tonight.   JG's propeller tests may shed some light.   At the end on the day a bit like trial and adjustment when you adjust the pitch and balance the propellers pitch to be the same for most minimal vibration etc.

[rgmwa]

Starting point for the RV12 is 4,600 on the ground at WOT, although I wouldn't assume that's necessarily applicable to other aircraft. 

Vans want the blades ideally set to within 1/10 of a degree of each other. I use a laser level as an inclinometer with a simple bracket that clips onto the prop. It's not too difficult to get it that accurate.  

[IBob]

Marty, on the Bolly  blades you will see a line left by the join in the molds. If you initially mount the blades with this line visible in the join between the front and back mounting plates, you will be very close and certainly close enough for test flights.
 

Static WOT RPM is not the most helpful measure, but FWIW mine is approx 5200RPM.

[IBob]

41 minutes ago, IBob said:

Marty, on the Bolly  blades you will see a line left by the join in the molds. If you initially mount the blades with this line visible in the join between the front and back mounting plates....

By that, I meant initially mount the blades that way, then use your clinometer/laser/whatever to pitch them all the same before flying.

I use a length of wood with a clamp on it to ensure each blade is brought round to exactly the same distance above the floor. And I use masking tape on the floor, and also on each blade where the laser is to be mounted: I measure in 222mm from each blade tip, using a sliding square set to that length, and mark that point with masking tape.

 

Finally, a pleasing check that you have all the blades pitched the same: at certain lower sun angles and directions of flight, the sun reflects off the back of the blades. With all the blades pitched the same, there will be little or no shimmy in that reflection.

[Marty_d]

Installed some dzus on the cowl - only got 2 done.  Fiddly but work well, so I'm happy with that. 

Edited April 18, 2022 by Marty_d

[IBob]

Belated thought:

On the suggestion of another builder, I drilled holes for 4 clekos to hold the upper and lower cowl together while fitting and adjusting the Dzus fasteners.

I believe this was to hold the two cowls in exactly the same position while drilling and fitting, so that all the fasteners were identically centered (since individual Dzus fasteners do allow some movement).

 

This is the only time I have ever fitted them, so I have no feel for what difference that may have made.

[Marty_d]

28 minutes ago, IBob said:

Belated thought:

On the suggestion of another builder, I drilled holes for 4 clekos to hold the upper and lower cowl together while fitting and adjusting the Dzus fasteners.

I believe this was to hold the two cowls in exactly the same position while drilling and fitting, so that all the fasteners were identically centered (since individual Dzus fasteners do allow some movement).

 

This is the only time I have ever fitted them, so I have no feel for what difference that may have made.

I already had it clecoed in all joining positions - around 16-20 I think, so the holes were already in position in 1/8".  I made a guide with 3 holes in the position of the DZUS centre hole and the 2 rivet holes, all 1/8", so I just cleco the guide to the existing holes, drill and countersink the other two, cleco the thin aluminium supports on the outside to guide expanding the middle hole to 10.5mm - then flip them to the inside and rivet them and the spring thingy together.

Then expand the outer cowl's hole to 10.5 as well (using a step drill seemed to work well and keep it centred).

[Blueadventures]

1 hour ago, Marty_d said:

Installed some dzus on the cowl - only got 2 done.  Fiddly but work well, so I'm happy with that. 

Hi Marty  The ones I've installed have a small washer over the spring curl to prevent the rivet end becoming loose or the spring clip coming off in time.  Cheers Mike

[Marty_d]

Good idea, thanks Mike.

[IBob]

You're way ahead of me there, Marty...........)

[Marty_d]

I've now got 10 out of the 19 DZUS installed - 4 each side and one each side of the prop hole.