Re: Maiden Flight! (return to service that is)


Jerry Marstall <jnmarstall@...>
 

I had similar problem when running a Volkswagen engine and the o-200. I concluded that my vent tube under the canard needed bent down more. As I increase angle-of-attack I concluded that the air coming across the face of the vent tube was being restricted due to the increasing angle of attack. But for insurance I also put in an axillary fuel pump.
Jerry 



Sent from my Verizon, Samsung Galaxy smartphone


-------- Original message --------
From: "Matthew Curcio mlcurcio89@... [Q-LIST]" <Q-LIST@...>
Date: 9/1/17 9:30 AM (GMT-05:00)
To: Q-LIST@...
Subject: Re: [Q-LIST] Maiden Flight! (return to service that is)

 

My gas cap is a rubber pipe plug style. I wrapped some heavy plastic on the outside of the neck and put some heavy rubber bands over that to act as a diaphragm and ensure there is no chance of a leak. I took it up for another test flight hoping this solved the problem and at first it seemed better but then no bueno. I coaxed it up to 2k feet and flew it around for probably 15 minutes and it runs just fine at lower power setting but as soon as you go full power after about 20 seconds the rpms drop to about 2050 and it won't come back until you bring the power back a bit. It is very evident that it is lean at this point. At the higher altitude I was more comfortable playing around with things. Its hard to tell exactly what rpm I am getting because the gauge is small and there is a lot of parallax, as it is on the right side of the dash. It looked like it was getting 2400rpm in the climb, at 100mph indicated - I am getting  1000 fpm climb there at 920lb gross TO weight and I though it would do better than that.


I feel confident now that it is not a venting issue related to the vacuum on the fill side of the tank. I am going to ground it until I can duplicate the problem on the ground and / or complete some thorough static testing. It seems clear that it is fuel starvation at high power settings and nose high attitudes. I regret not checking if it would still do it in a more level attitude. When I checked static fuel flow in the 3 point attitude a couple of months back I was getting about 20gph and I believe as Jim indicated that 15 gph is the minimum (10gph is the max fuel consumption at full throttle for the O-200 per the manual). My plan for now is to make up a big test cowl like used for run-in so that I can tie the airplane down and run it long enough to hopefully get the problem to occur. I would like to remove the gascolator from the system but I am not comfortable flying another test before doing some thorough static testing. I am confident if it is vapor lock that it will not occur on the ground. Extensive static testing will at least rule out some of the potential causes for fuel starvation; then, I will be left with the aerodynamic venting issues and vapor lock.


I wish I had a nice 3 mile long runway so I could feel more comfortable with an engine failure shortly after take off. I could rig up a pressure / vacuum gauge to read a few inches of WC into the header tank that would be the tell all for the venting issue.


On a related-unrelated note, the engine doesn't seem to be developing full power but that may be a function of the propeller pitch. What kind of climb rate can you get at around 900lbs? 


Matthew Curcio

734.693.6326





From: Q-LIST@... <Q-LIST@...> on behalf of 'jcrain2@...' jcrain2@... [Q-LIST] <Q-LIST@...>
Sent: Thursday, August 31, 2017 11:52 PM
To: Q-LIST@...
Subject: Re: [Q-LIST] Maiden Flight! (return to service that is)
 
 

One last throw of the dart at this topic.  There can be a low pressure area behind the exit air of the cowl.  If the tank vent is close to that it can do strange things.
 Also if the tank vent comes out the bottom of the fuselage and makes a bit of a bend back up it can form a P-Trap, like in plumbing, if it fuel sloshes out the tank into the vent tube.  Look at those two things closely.  I put the vent out the top of my header tank for this reason.  Did  Kevin Boddicker make a longer vent tube out of the bottom of his fuselage with a short bend forward to avoid the P-Trap effect?  Help me out here "Special K"!
Bruce Crain

---------- Original Message ----------
From: "Matthew Curcio mlcurcio89@... [Q-LIST]" <Q-LIST@...>
To: Q-LIST@...
Subject: [Q-LIST] Maiden Flight! (return to service that is)
Date: Thu, 31 Aug 2017 12:11:50 +0000

 

I was able to make the maiden flight on the quickie Q200 I have been working on the past couple of months. It has 235 hrs on it but hasn't flown in about 15 years. As I said in an earlier message I had been doing some high speed taxi testing 70-75 mph and felt comfortable. The weather conditions were perfect last night and the airplane and I were ready to go. I spent quite a bit of time flying the chair yesterday and briefing up on a plan with a friend who has a lot of experience doing first flights. Flying wise it went great but I found I have some issues with the engine I need to resolve:

 

Right after takeoff I felt the engine lose a little power it was at that point where you're not high enough to turn around or make another runway and your not low enough to land ahead. I was still climbing but obviously nervous the situation was going to deteriorate. The engine was running smooth the entire time it was just a loss in power. The power seemed to come back at some point but it was not a very noticeable surge. I kept climbing and  turned towards the other runway so I was within glide range if I lost it. I believe it did it two more times. I set up for a landing and brought it in.

 

I was really pleased with the ground handling and flying of the airplane. Take-off run was fine and the landing I thought was very easy. I just flaired and held it right above the runway bleeding off all of the speed until the stick was all the way back and the airplane settled right onto the runway smoothly no bounce or shimmy.

 

Questions:

 

- What do you see on the tach in a climb at 100mph with a stock O-200?

- Thoughts on the cause of the power surge?

 

I'm getting a carb rebuilt kit here asap. I know I'm getting air, I know I'm getting fuel to the carb. That leaves carb and ignition. I think it is most likely that the carb has some build up on the hi speed jet or something to that nature. I discussed this with an experience A&P friend as well and he agreed and said it didn't sound like a mag issue he has ever come across. I know vapor lock could be a concern, I do have a gascolator mounted on the firewall. It is on the far left side and I put a tightly sealed aluminum enclosure around it with a small naca scoop in the cowl pushing cool air in direcetly at the top of the enclosure and then it flow out the bottom. Your thoughts are welcome.

 

 

 

Matthew Curcio

734.693.6326


 



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