Quantcast

CriCri MC-15 in NZ

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

vondeliusc

Active Member
Joined
Aug 13, 2009
Messages
43
Location
Kalispell, MT, USA
My main concern would be if the wires migrated forward into the flywheel; that might be bad. Otherwise, some quality fresh locktite would probably be fine, along with some torque-stripe (marking) on each for a check during preflight. Many bolts on the helicopters had torque-stripe which is easy to visual before each flight, as you can see on this R22 tailrotor. I really appreciate that you are documenting your build so thoroughly; a huge asset to other builders.
-Christian
R22 robinson-helicopter-tail-rotor.jpg
 

MadRocketScientist

Well-Known Member
Joined
May 16, 2009
Messages
1,659
Location
Canterbury, New Zealand, Earth, Milky Way Galaxy.
My main concern would be if the wires migrated forward into the flywheel; that might be bad. Otherwise, some quality fresh locktite would probably be fine, along with some torque-stripe (marking) on each for a check during preflight. Many bolts on the helicopters had torque-stripe which is easy to visual before each flight, as you can see on this R22 tailrotor. I really appreciate that you are documenting your build so thoroughly; a huge asset to other builders.
-Christian
Thanks for the kind words :cool:

That paint is exactly what I have in mind! In the homebuild community over here it is very common practice to use that paint on all bolts. It is something that has such a big benefit for so little effort.

The music wires on my engines are directly in line with the stainless ring gear, so they would hit that if they moved far enough. However there is much more clearance between the ring gear and the wires than there is between the bolts holding the engine together (500 24) and the engine mount itself (501 04). If the engine moves forwards, the bolt heads rub on the engine mount long before the music wires get anywhere near the flywheel. :) If both ends of the music wires are slipping, someone has really forgotten to tighten the clamp bolts! I can imagine that it would create quite a few sparks.

I have shifted the adjustment end of the wires to the rear of the engine, rather than the front as shown in the JPX plans. There isn't enough clearance to be able to adjust them facing forwards.
 

MadRocketScientist

Well-Known Member
Joined
May 16, 2009
Messages
1,659
Location
Canterbury, New Zealand, Earth, Milky Way Galaxy.
I finally sorted out the screws for holding the o-rings in place. The previous ones I purchased were a little too sort to hold three o-rings at once. I was using 4g x15mm and instead I found some 6g x18mm. I had to sleeve the shank as the threads go quite far up the screw and could cut through the o-rings, or at least damage them.

The 6g screws were slightly too big to fit on some K&S 5/32" brass tube, so I held them in a collet chuck int he lathe and filed them down a little,
DSC00300 (Medium).JPG
I little reduction in the screw size and the sleeves fit over pretty well,
DSC00303 (Medium).JPG
I needed a dozen or so sleeves and needed to come up with a quick way of cutting short lengths of brass tube accurately. I grabbed another short length of 5/32" alumnium tube and used it as a stop inside the cordless drill chuck. I cut it just long enough that the brass tube could be inserted in front of it and then cut off flush with the drill chuck jaws to make the correct length.
DSC00305 (Medium).JPG
I cut the brass tubing into the 8.5mm lengths using a Tajima heavy duty box cutter while the drill is spinning. I cleaned the ends up with a needle file in the same drill to remove and burrs.
DSC00306 (Medium).JPG
And here is the difference in the screw sizes. The sleeved screws have a larger bearing area for the o-rings to sit on.
DSC00299 (Medium).JPG
With the o-rings installed.
DSC00307 (Medium).JPGDSC00310 (Medium).JPG
Little jobs like this seem to take up a lot of time, especially when the specified hardware seems to be unobtanium!
 

MadRocketScientist

Well-Known Member
Joined
May 16, 2009
Messages
1,659
Location
Canterbury, New Zealand, Earth, Milky Way Galaxy.
What are the engines?
I might be wrong, but they look to be Yamaha DT-180 engines. There is a CriCri in Brazil with the same engines.
I am not sure why this one was painted black, terrible idea really with it being a composite structure.

Edit: this is the same CriCri as in the video above, it seems that PP-ZCE has a new paint job..
 
Last edited:

proppastie

Well-Known Member
Log Member
Joined
Feb 19, 2012
Messages
4,757
Location
NJ
Maybe left Carbon fabic bare?
Do they cut off the back of the case? Any idea on the weight?
 

MadRocketScientist

Well-Known Member
Joined
May 16, 2009
Messages
1,659
Location
Canterbury, New Zealand, Earth, Milky Way Galaxy.
Something interesting that I came across, a somewhat related article about tufting an MCR 4S (from the same designer as the CriCri with a very similar tail).


This picture is interesting in that the affected area under the elevator is quite large. I wouldn't have suspected that the airflow was disturbed quite as much from the gap in the intersection of the fin and elevator. The CriCri would be very similar. The article also has a short air to air video.
snapshot20051219034920.jpg
 
Last edited:

Speedboat100

Well-Known Member
Joined
Nov 8, 2018
Messages
1,615
Location
Europe
Something interesting that I came across, a somewhat related article about tufting an MCR 4S (from the same designer as the CriCri with a very similar tail).


This picture is interesting in that the affected area under the elevator is quite large. I wouldn't have suspected that the airflow was disturbed quite as much from the gap in the intersection of the fin and elevator. The CriCri would be very similar. The article also has a short air to air video.
View attachment 103841
Does cri cri have all moving elevator ?
 

Jay Kempf

Curmudgeon in Training (CIT)
Lifetime Supporter
Joined
Apr 13, 2009
Messages
4,130
Location
Warren, VT USA
Something interesting that I came across, a somewhat related article about tufting an MCR 4S (from the same designer as the CriCri with a very similar tail).


This picture is interesting in that the affected area under the elevator is quite large. I wouldn't have suspected that the airflow was disturbed quite as much from the gap in the intersection of the fin and elevator. The CriCri would be very similar. The article also has a short air to air video.
View attachment 103841
Two things going on in this picture. First is the bow wake of the leading edge of the Vtail. Second is the gap. Third is that the leading edges are lined up. Many gliders have their Vtail and Htail LE's offset from each other for that reason. Sealing all the gaps smoothly even without a fillet would clean that up significantly. If an all flying tail a tight fitting fairing extending down from the Htail would help a lot. It would have to have enough clearance for movement of course. Many high performance sailplanes have no real fillet on the Htail to Vtail transition and only a vinyl taped seal.

I wonder how much the canopy effects that area of flow on the Cri Cri?
 

MadRocketScientist

Well-Known Member
Joined
May 16, 2009
Messages
1,659
Location
Canterbury, New Zealand, Earth, Milky Way Galaxy.
Two things going on in this picture. First is the bow wake of the leading edge of the Vtail. Second is the gap. Third is that the leading edges are lined up. Many gliders have their Vtail and Htail LE's offset from each other for that reason. Sealing all the gaps smoothly even without a fillet would clean that up significantly. If an all flying tail a tight fitting fairing extending down from the Htail would help a lot. It would have to have enough clearance for movement of course. Many high performance sailplanes have no real fillet on the Htail to Vtail transition and only a vinyl taped seal.

I wonder how much the canopy effects that area of flow on the Cri Cri?
I wouldn't think the disturbed flow would be from the canopy. The canopy is quite smooth, the large gap between the fin and elevator is a different story however!
 

fly2kads

Well-Known Member
HBA Supporter
Joined
Jan 2, 2010
Messages
1,727
Location
Justin, TX
From that pic, and the one on their site of the rudder side view, it looks like there is a whole cone of disturbed air coming off of that dirty intersection. I'm not surprised to see the tufts on the fin and rudder follow the flow field of the stabilator. What is interesting is the flow at the rudder trailing edge going completely vertical!
 

MadRocketScientist

Well-Known Member
Joined
May 16, 2009
Messages
1,659
Location
Canterbury, New Zealand, Earth, Milky Way Galaxy.
From that pic, and the one on their site of the rudder side view, it looks like there is a whole cone of disturbed air coming off of that dirty intersection. I'm not surprised to see the tufts on the fin and rudder follow the flow field of the stabilator. What is interesting is the flow at the rudder trailing edge going completely vertical!
I thought that was interesting too! The flow goes upward as it passes the trailing edge.
 
Top