Quantcast

What did you do on your airplane project today?

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

Marc W

Well-Known Member
Joined
Mar 31, 2017
Messages
504
Location
Colorado
I have put 10.7 hrs. on the CX4 since reassembly. I had made a number of changes and had one cylinder head off. Today I pulled the cowl and checked things out. I checked the torque on the head I had removed, adjusted the valves, torqued the prop bolts and generally checked nuts and bolts for tightness and looked things over. The head nuts were fine, but the prop bolts did need a little tightening. I had one exhaust valve that had tightened up about .001" since initial setting. I tweaked a few other valve adjustments to get them just so.

Other than that the only thing I found was that my new carb heat muff was rubbing on the cowl. I was able to bend the corner in a bit by hand to take care of that problem. It is good to go! Airborne in the morning!
 

cblink.007

Well-Known Member
Joined
Jul 7, 2014
Messages
410
Location
Texas, USA
Today, I picked up a Yamaha Apex engine via local ad on Craigslist. Apparently the seller bid on a storage unit, and under all the horde was a snowmobile...and it ran! The chap gladly sold it to me for $500, because who else in Houston was looking for a snowmobile?? It had under 300 miles, looked like it had a bad shunt, but the engine was mint...but still needs to get disassembled, cleaned and freshened up as part of the conversion process.

He told me he was the winning bidder on the unit at $150, so we both made out like bandits!

Also, all finishing and paint is finally complete on the 25% scale test model!!

#winwin
 
Last edited:

Victor Bravo

Well-Known Member
Joined
Jul 30, 2014
Messages
7,699
Location
KWHP, Los Angeles CA, USA
Picked up powder coated struts today, they look good. Plenty of rosette depressions and the splice between the wrong length and right length struts. But they will look just fine underneath the opaque fairings!

Leaving 0530 tomorrow morning to do the clandestine sheet metal deal for the formed trailing edge. Gotta get there after my guy shows up to open the shop, but before their guy shows up to watch the employees :)
 

Victor Bravo

Well-Known Member
Joined
Jul 30, 2014
Messages
7,699
Location
KWHP, Los Angeles CA, USA
Classified Stealth Sheet Metal Project Completed. Got four pieces of fabricated trailing edge and four pieces of semi-fabricated leading edge for my flaps and ailerons. I have to find some way of compensating the guy at the sheet metal shop (who would not take a dime). Photos forthcoming at some point soon.

Total cost slightly exceeds the equivalent of buying the trailing edge parts from ACS:
$100, because I had to buy a whole sheet of aluminum.
5 gallons of car gas, one protein bar, one high-caffeine energy drink, and a quart of oil for the old Volvo... about $40

Not having to wait one WEEK for ACS to get the trailing edge material... PRICELESS !
 

Toobuilder

Well-Known Member
HBA Supporter
Log Member
Joined
Jan 19, 2010
Messages
4,858
Location
Mojave, Ca
Did A 1.1 in the Rocket today to start zeroing on on engine tuning. I punched my standard flight plan to Phoenix into the GPS, pushed the AP button, and let the airplane do its thing up to 9500 while I watched for traffic and monitored the engine. The program Ross loaded into the CPU was pretty much spot on in maintaining the best power EGT target all the way to TOC. No mixture fiddling required. At cruise, the speed stabilized at about 197KTAS. Manual leaning with the knob gave me a good idea of the peak EGT fuel flow, and this delivered the expected sag in speed. With magnetos, you simply live with this sag in speed because generally, your overall MPG has increased. But with Ross' ignition, you add advance via the LOP switch and some of the speed comes back - I've discussed this many times on this and other forums. But with the EFI, the LOP switch not only adds ignition advance, but it also makes the appropriate cut in FF, so the old routine of fidling with mixture to find peak EGT, seeing the sag in speed, flipping the switch and seeing the speed come back is replaced with a seamless flip of the LOP switch. So as todays example showed, my best cruise speed was 197@13.5 GPH... When I flipped the LOP switch, the FF dropped to 10.5 GPH and the speed did not change. It is incredible. A savings of 3 GPH for the same speed! That extra 9 gallons on board at the end of a 3 hour leg is a very useful thing to have, not to mention the cost savings over the life of the airplane.

Yes, it is but one data point, but pretty favorable. My goal with the airplane is to be able to flight plan for 200KTAS@10GPH, so I'm close. There are more than a few knots tied up in the rough cowl, misaligned gear leg fairings, and huge gaps in the wheelpants. More to follow.
 

Toobuilder

Well-Known Member
HBA Supporter
Log Member
Joined
Jan 19, 2010
Messages
4,858
Location
Mojave, Ca
Yep, and aside from the ported heads, its the same basic architecture that left the factory. No high compression pistons or anything to add stressors. Looking forward to dumping the truly awful updraft sump for the tuned (300hp) version. Should improve cylinder to cylinder variation and VE.

Noticed something discouraging about my finely crafted induction airbox. Because the SDS EFI programmer has a direct readout, I can easily compare the OAT (free stream) and Inlet air temp. I'd like them to be the same, but it looks like I'm picking up almost 30 degrees between entry and throttle body. With no venturi and worry about carb ice, added heat simply costs me power. The airbox is so big that it sucks up a lot of lower cowl heat. I may try to wrap it in reflective aluminum tape to see if that makes a difference. I might also look to incorporate the engine mounted airbox into the lower cowl itself, removing one side of thermal exposure.
 

plncraze

Well-Known Member
HBA Supporter
Joined
May 11, 2006
Messages
1,862
Peter Garrison has dealt with this on his plane. Website is Melmoth2.com he reversed the intake on his engine to try to cool the induction temp if I remember correctly.
 

Victor Bravo

Well-Known Member
Joined
Jul 30, 2014
Messages
7,699
Location
KWHP, Los Angeles CA, USA
Spent all day at the hangar, and managed to repair my flap using the newly fabricated Trailing Edge and Leading Edge material. Before anything else I had to saw off the wooden trailing edge, and when I did that I saw that there had been repairs there already. The sharp pointed trailing edge of the ribs just wasn't thick enough or wide enough to hold the aluminum TE on with screws.

Most of today was spent doing safe, but quick and dirty metal work to get the busted flap ready to recover. The sheet metal shop that made the raw material for my flap did a pretty good job. The trailing edge had stiffening "return" flanges that were wider than I wanted, because the press brake they used couldn't grab the metal any closer to the edge. The brake also was able to fold the trailing edge maybe 135 degrees, I'd have to close ot the rest of the way myself. I did this, using everything from hand pressure, leaning on it while it was on the bench, wide "seaming pliers", and even a plastic mallet.

Finally got it close enough for this use. Looked just fine, especially with the fiberglass strapping tape holding it in place on the ribs. Not really wanting to trust an aluminum-to-wood glue joint, I realized that any holes drilled for nails, screws, etc. would just weaken the tiny little wedge of wood at the TE. Believe it or not, the tape seems like the best way; the fabric tension will hold the TE where it needs to be very securely, and this makes it even more secure. If I had the luxury of aluminum flap ribs, one little -3 rivet would have been great. But not in wood.

Then I tackled the leading edge. I had a 4.5 inch wide C-channel with 3/8" flanges made for me. But how to bend this channel to the shape of the flap rib airfoil? For some mysterious reason, I didn't have a very small diameter but 6 foot width capacity slip roll to work the metal into a curved leading edge skin. Answer: a lot of hand forming, leaning on it, and tapping with a mallet. Folding it around a dowel, and hammering the dowel into the leading edge for a radoius. Needing to put a little over 1/8" radius at the leading edge. Trying to use the palms of your hands as a slip roll.

In the middle of this effort, I realized that I had come up with a great new joke for comedian Jeff Foxworthy, if he ever decides to do stand up comedy at an EAA meeting:

"If you know how to use the crevice between the hinged door panels of your hangar as an emergency sheet metal brake... you might be a redneck pilot."

I had a six foot piece that needed a crease in it, and I only had access to a 2 and 4 foot brake at my airport.

So here are the photos I promised. One showing the TE material before hand-fitting it to the flap ribs. A few showing the flap leading andtrailing edge skins held in place. Flap With New Alum LE & TE 1.jpgFlap With New Alum LE & TE 2.jpgFlap With New Alum LE & TE 3.jpgFlap With New Alum LE & TE 4.jpgNew Trailing Edge Stock 1.jpg
 

Toobuilder

Well-Known Member
HBA Supporter
Log Member
Joined
Jan 19, 2010
Messages
4,858
Location
Mojave, Ca
Flew another 1.1 and changed the oil for the first time. The cylinders are broken in and it's time to run the real oil. Break in oil came out looking much like the honey color it went in, and the main oil strainer is almost perfectly clean - only one or two smal flakes of stuff.

Most of my enroute time was at 12.5k and I made some interesting performance measurements with this new prop. Stabilized at my normal LOP fuel flow setting I did an RPM sweep from 2300 to 2600 RPM to see what it did for FF and TAS. Note I changed ONLY the blue knob - the throttle remained against the stop and the SDS ECU did the rest. Numbers: RPM/GPH/KTAS

2300/9.7/193
2400/10.2/197
2500/10.6/201
2600/11.0/201

Looks like the prop hits a wall at 2600 at this TAS. More experimentation needed.
 

Mcmark

Well-Known Member
Joined
Sep 24, 2013
Messages
382
Location
Owings, MD
Took time off from work and spent the week in PA working on my SS101 biplane.
We intended to run the engine but the impulse coupling wasn’t. That was after rewiring the battery. Tried to get it apart and make at least a half fast repair but HULK was operating puller, HULK smash.
So, I started installing the Vans baffle kit. I thought it a bit pricey... then I started the install. Of course, I’m using a conical mount, so much cutting and trimming to adjust and then it’s a GPU case which has lumps and bumps everywhere else, so more cutting and fitting.
As it stands right now I’ve got 45-50 hours in the baffling and not done yet. Still have the rubber seal to complete, under cylinder rods to install and silicone all the edges and such. I mounted the oil cooler on the front left with a doubler and a brace to the cylinder. Seems very stout.
I’ll say the Vans kit is worth every penny. Virtually every thing you need is in the kit and then some.
After what amounted to 5 12 hour days, I’m getting closer but still have a ways to go.
Bunches of clean up and tighten up, only 1 hose to make for MP gauge, hang the wings and rig, rebuild heal trays, button up all the panels, fairings and such plus all the items above. It adds up.
Contemplating bringing it home to ESN so I can at least get to it easily. A weekend to get it home but an hours drive beats 4.5 each way.
 

TFF

Well-Known Member
Joined
Apr 28, 2010
Messages
13,405
Location
Memphis, TN
The Vans kit is worth every penny. Doing baffles without it would surely double build time. Finish the one already at home first.
 

Daleandee

Well-Known Member
Joined
Sep 11, 2015
Messages
1,142
Location
SC
While doing the condition inspection I found something that needed correcting that seemed like a great idea eight years ago when the aircraft was completed. Where some wiring comes through the firewall they had all been put through a single hole with a grommet. It was a tight fit. Over time heat dried and cracked the grommet. I didn't get a photo before removing remains of the old grommet but did after removing the cracked and broken pieces:

1597023431263.png

As you can see there isn't much for clearance. It was decided to remove the red/yellow wires as these are for the CHT & EGT sensors:

1597023599041.png

Then a second hole was opened and the sensor wires moved into it.

1597023685416.png

These will be sealed after all the wiring connections are completed and checks are done to be certain all is correct. I was ecstatic to find no visible damage to any of the wiring. I must say that under the panel of a Sonex in the heat of August is one way for an old man to find out the state of his health. 🥵
 

Attachments

Doran Jaffas

Well-Known Member
Joined
Jun 25, 2019
Messages
216
I was able to check my tachometer for accuracy today. It reads high thankfully. Took it up, checked airspeeds against actual rpms and am very pleased with the little Tailwind W8's performance with the 0-200 for power. Took it up and just had fun with N625MS today😁
 

Attachments

Top