BEARHAWK ~ Fuel Flow Test (Part 2 Airworthiness Certification and Phase 1 Flight Testing)
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- Опубликовано: 13 мар 2021
- BEARHAWK - This is an important day! The majority of failed first flights are a result of fuel starvation.
The fuel flow test is performed in a worst case scenario flight attitude. The tanks are holding a minimum amount of fuel (about 5 gallons each) and the pitch attitude is set to nose high.
This airplane is fuel injected and has two fuel pumps. 1) is the engine driven fuel pump that supply continuous fuel pressure to the fuel servo. 2) is the boost pump located under the cabin floor and behind the firewall. The he boost pump only runs at certain times and is not continuous.
In this fuel flow test, we are looking for 125% of 25.21 Gallons per Hour, or a minimum of 31.51 GPH.
As you see in the video, I was able to well exceed 31.51 GPH.
The locations and conditions for the fuel flow tests were as follows:
* Fuel flow from the servo inlet, boost pump ON
* Fuel flow from the servo inlet, boost pump OFF (Gravity)
* Fuel flow from the engine driven fuel pump, boost pump off (Gravity)
I was able to see 32.8 GPH at the engine driven fuel pump inlet with fuel selected to both on the gravity test.
The results are not looking very favorable with neither of the two pumps online at the servo inlet. But I think I can lose either of the two separately and still be in good shape.
Will test further with engine running and boost pump off at higher RPM's. Will be looking for 25+ PSI there.
This video series covers my progress building (and eventually flying) the Bearhawk 4 Place. See my "About This Channel" here: • BEARHAWK ~ About this ...
This aircraft is powered by the Lycoming Thunderbolt YIO-540-EXP. www.lycoming.com/engines/thun...
Check out more information on all the Bearhawk Models here: bearhawkcanada.ca/ & bearhawkaircraft.com/
I am logging the details of my build project here: bearhawk4place.blogspot.com/
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BEARHAWK LIFE DISCLAIMER:
I am a 900+ hour pilot with various ratings including instrument, commercial, multi-engine instrument, CFI, CFII. Those ratings were obtained YEARS ago and do not suggest that I am an expert today. The purpose of these videos is to 1) share my experience building an experimental amateur built aircraft, 2) promote the most underrated, under-promoted Bearhawk back country utility taildragger aircraft in the world. Recording the building and flying help me with self analysis for my own personal improvement. Nothing in these videos should be taken as absolute fact and are not intended to replace professional guidance from a A&P, IA or a CFI... Feedback is invited; however please keep it positive.
Rob Caldwell
Reminds me..I buildt a kitfox...so much fun ...400 hrs. Of flying in fact ..nothing like experimental aviation
Thanks for the explanation and information. I didn't realize that it got so concise and specific. I can only imagine a fully aerobatic aircraft calculation must be a nightmare.
Great content
Rob, I got to admit I was a bit worried as you elevated the aircraft (in pitch) with only the tail wheel secured by chocks and also there appeared to be no one there with you in the unfortunate event that there was a mishap, god forbid.
I don't understand something here. I got all the BSHP calculations and they look correct. What I'm missing is the fact that you don't seem to be taking into account the engine-driven fuel pump when you are calculating the required flow. The engine-driven fuel pump is going to lower the pressure in the fuel lines from the tank so it will flow more than it would through gravity alone.
Loving these vids. Just got my plans this week. Hopefully will have the kit this summer. On your gravity test.....wouldn't you get more flow in flight due to pressure in the tanks from the forward facing vents? Does the ground test values already account for the that?
Are the specified amounts and percentages for that engine according to FAA? Or is it for the high wing configuration?
I’m sure you know what is happening but I don’t like it, no sir, not one bit!
I couldnt make it to the content, the music is horrible!!!!