What did you do on your airplane project today?

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Doran Jaffas

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Jun 25, 2019
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I have done some test piloting of experimental and factory built aircraft. I'm probably speaking to the choir here but have a plan and stick to it and do not make it too complicated. The objective of the first flight frankly is to get it up in the air and back on the ground safely. My first test flight that did years ago was literally one trip around the pattern and in for a landing. I had done some high-speed taxiing so I knew approximately what speed the airplane going to land at. Add 10% and allow the airplane to float down the runway until it is ready to settle.
Do not get ahead of yourself and do steep or aggressive maneuvers at first. If everything feels good once you get in the pattern then the engine gauges are telling you all is well taking a couple of circuits around the pattern to calm your nerves before that first landing is not a bad idea but again please don't make the first test light complicated. there is plenty of time in the ensuing test lights and program for that. Also, I know for posterity many people like to include an in-flight camera but that is also a distraction you do not need. Better is just save that for the next flight or even several flights later after you had become acquainted and I'm more comfortable. If you want something for posterity have a still photo taken after you land. Even knowing someone is videotaping you on the ground can add unneeded distraction.
 

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Toobuilder

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Mojave, Ca
Decided to fly this morning before work (and before the heat). Took off a bit before dawn at 69 degrees, and climbed to 7500 feet where it was 80 degrees! Oil cooler mods are "better" but not a dramatic change. I'm going to press on with it in this configuration to see if additional break in takes a bit more edge off the temps. Time to now focus on the finer points of engine management and aero cleanup. I have a Spruce order coming that includes some SS sheet that I'm going to roll into augmentor tubes. The current augmentor duct is holding up OK, and removal of the "spoiler" did not change belly temps for the worse - if anything, they might be better. I might try again this afternoon, but I'm not looking forward to flying in 100+ degree heat, epic dust devils, and gusty winds. Will probably just have a beer instead.
 

Victor Bravo

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Jul 30, 2014
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KWHP, Los Angeles CA, USA
Verifying my delightfully firm grasp of the obvious, I agree that engine break-in has a pretty high probability of lowering temps by some measurable amount. How much I don't know, it will depend on all sorts of details of your overhaul, chrome jugs vs. plain jugs, piston clearance, bearing crush, and a hundred other things. But I can't imagine there being any less than 15-20 degrees of oil and cylinder temperature drop after 10-15 hours.
 

Toobuilder

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Bill - I'd be thrilled with a 15 degree reduction after break in. Realistically though, my oil consumption is already stabilized and my CHTs are well under control. I'm not sure what's left. The only compelling variable left is my addition of piston cooling jets at rebuild. This adds a significant heat load to the oil and my cooler may not be up to the task. My "too cool" CHT might be at the expense of the oil temp. Robbing Peter to pay Paul, so to speak.

Byron - went with plan 14 ...
(seven and seven)
 
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cblink.007

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Jul 7, 2014
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269
Location
Texas, USA
Finishing on my test model is complete...now on to the painting phase!

20200706_131930.jpg
20200706_140606.jpg
Also, before applying primer to the wings, the elevons and servo bay access panels were cut out:
20200706_144028.jpg
20200706_144048.jpg
Given that priming is pretty much the final phase of finishing, we will still be sanding a little bit with the wings reinstalled, then will pull the wings back off and paint! After painting, the last part of the structure, the motor mount and canopy structure will be taped to the centerbody, elevon hinges and electronics installed. Then ballasting, test equipment installation, system checkouts.....then we go fly!
 

Marc W

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Mar 31, 2017
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468
Location
Colorado
I finished buttoning up the Thatcher this morning. I could have flown it. The wind died to almost nothing about the time I got done and it was not to hot. AWOS reported density altitude on the field of 8000'. I was tired and decided to fly it early tomorrow.
 

Victor Bravo

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Jul 30, 2014
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KWHP, Los Angeles CA, USA
Finishing on my test model is complete...now on to the painting phase!

Given that priming is pretty much the final phase of finishing,
For whatever it's worth, I humbly suggest you fly it in primer. Time/weight/cost/delay spent on paint at this stage is just not prudent at all. This is a test model to see if an entire design concept is going to work... what do you think the odds are that it will not need any sort of tweaking, moving a hinge line, lengthening an elevon, fixing the landing skid, adding some little VG or fairing, adding an ounce of weight somewhere, moving the towhook position, etc. etc. etc.?
 

cblink.007

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269
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Texas, USA
For whatever it's worth, I humbly suggest you fly it in primer. Time/weight/cost/delay spent on paint at this stage is just not prudent at all. This is a test model to see if an entire design concept is going to work... what do you think the odds are that it will not need any sort of tweaking, moving a hinge line, lengthening an elevon, fixing the landing skid, adding some little VG or fairing, adding an ounce of weight somewhere, moving the towhook position, etc. etc. etc.?
Input appreciated, and we agree with you, but there is a method to the madness! We actually considered flying with primer only, but this thing actually needs a little amount of weight, even before we load her up for dynamic scaling. That paint will help with mass properties. And no towhook/skid on this beast...just landing gear. Even with all this, we know some mods are inevitable.. we already have five different engine cowling shapes and VGs we want to evaluate. At least it will look good while functional! There are plenty of compartments for ballasting in it. Why all the effort? Good hands-on education for the first-time builders on the team, despite the fact we are all ex-military XPs and FTEs. We do not want a Raptor-tier s##tshow with this project, but it has been a blast so far!!!
 

Marc W

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Mar 31, 2017
Messages
468
Location
Colorado
It was a beautiful morning to fly the Thatcher. I took off at 6:30 AM and landed about 8:00 AM. Density altitude was a mere 6,300' at takeoff and winds were light. The engine ran better than it ever has. I gained around 100 RPM in the climb over what it used to run. I had done some valve work and replaced the magneto and spark plugs. I also modified the intake manifolds. Now I wonder how long the old mag was failing.

I stayed over the airport for the first 30 minutes and everything was working so I went sightseeing. I went up to 11,000'. I was surprised to see there is still some snow in the crevices above 10,000'. It has been hot so I wasn't expecting that.

I had been getting engine fumes in the cockpit so I cleaned and resealed the firewall and relocated the cabin fresh air vents while the plane was down for engine work. The new vent locations worked much better and I didn't have fumes in the cockpit. I also had changed the exhaust from 4 into 2 to 4 straight pipes. I think the four straight pipes are louder and the exhaust has a more ragged sound.

I did have a couple small issues. I have been running auto gas with 10% ethanol. I have a vapor locking problem with the ethanol gas when gravity feeding the carb. The airplane has two fuel pumps and I don't get vapor lock with the fuel pumps on but I want the gravity feed to work. The airplane has a 10 gal. tank under the front cowl so it doesn't have much head pressure. It has a gascolator at the bottom of the firewall. I made a little aluminum dog house for the gascolator and rigged a blast tube to feed it cool air. That effort was partly successful. The engine ran fine on the gravity feed until the fuel level dropped to under half full. Then I had to run the fuel pump. I probably need a bigger and better blast tube to make it work at low fuel levels.

The other issue is I need to adjust the idle. The engine died on final when I pulled it back to idle. It had been idling a little low but I left it alone because it idles better when hot so I always adjust it right after I fly. It wasn't a problem because I was a little high if anything.

The fine tuning isn't over but I am pleased with how it all went.
 

Pops

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USA.
Congratulations from Pops. Big step.

I set today and read all of the EAA's Test Flight Manual and test cards. The more I read the better I like it. Very good instructions.
 

Doran Jaffas

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Joined
Jun 25, 2019
Messages
177
Decided to fly this morning before work (and before the heat). Took off a bit before dawn at 69 degrees, and climbed to 7500 feet where it was 80 degrees! Oil cooler mods are "better" but not a dramatic change. I'm going to press on with it in this configuration to see if additional break in takes a bit more edge off the temps. Time to now focus on the finer points of engine management and aero cleanup. I have a Spruce order coming that includes some SS sheet that I'm going to roll into augmentor tubes. The current augmentor duct is holding up OK, and removal of the "spoiler" did not change belly temps for the worse - if anything, they might be better. I might try again this afternoon, but I'm not looking forward to flying in 100+ degree heat, epic dust devils, and gusty winds. Will probably just have a beer instead.
Sorry about all the type of graphical errors there. Voice texting can be a...
 

Victor Bravo

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Jul 30, 2014
Messages
7,402
Location
KWHP, Los Angeles CA, USA
So today, I took a few measurements, made a few ink marks, took a very deep breath, probably puckered my underwear all the way up into you know where... and took a !(#*% chop saw to my wing struts.

The rest of the day was spent measuring and cutting and rosette-hole-drilling the new (one size larger diameter) 4130 tubes to slip fit over the original end fittings I had cut out of my struts.

(This has nothing whatsoever to do with the thread I started a month or so ago, asking for technical advice on whether splicing larger diameter tubes onto existing strut end fittings would be as good as building new struts. Nothing whatsoever. That thread was for a totally different project, that I can't discuss, because I had to take a ride in an unmarked 737 out of Las Vegas to go work on it.)

But on my non-classified project, which is the subject of this posting, tomorrow a friend will be welding the lower half of the struts together on a bench, then we'll hang the wings on the little Ridge Runner and pin the struts in place, then make sure the wing dihedral is the same from left to right, then tack the upper strut fittings, then disassemble the airplane, then hopefully finish weld the outboard fittings onto the struts.

This will take the outside diameter of the strut from 3/4 to 7/8, adding significant resistance to buckling under negative G gust loads or landing loads. Believe me I ain't doing this for any intentional aerobatics, it's for when the Mojave Desert wants to act like the Mojave Desert.
 
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