Bookmarked that post, super super helpful stuff. Thanks
@koolkei’s airplane goes further in spite of a slightly higher fuel burn for a few reasons:
First, his takeoff roll and climb to optimum altitude are faster; seven minutes for him versus ten minutes for you. Since all of this is done at maximum rated power, your aircraft burns a bit more than a kilogram more fuel in this phase of flight than koolkei’s. And at his cruise speed of 109 knots, one kilo of fuel is good for about 9 additional nautical miles of range.
Second, his fuel burn per distance is 2.6 percent better than yours was, simply because his cruise speed was that much higher. So, over his entire cruise leg, it gives him an additional 12 nautical mile advantage to the top of his descent.
Finally, his lower cooling needs and different propeller meant his aircraft had slightly less drag than yours, which means in the descent phase, he could not descend as quickly as you could. Since descent is spent at idle power (and zero fuel burn), his longer descent covered quite a bit more distance than yours did, even with you starting at a higher altitude. This accounts for the rest of the difference between your airplane and his.
After a considerable amount of experimenting around with the LUA files and the Curves data, I found that taking the in-game value produced results so close to the Curves data that it really didn’t make much sense to fuss around and extract the numbers I needed.
Flat-rating can save you some cost and weight in the propeller and gearbox, while giving you better altitude performance, but at the expense of having an oversized engine for your application. It’s up to you if you want if you feel the benefits outweigh the advantages.
OOHH. engine cooling is also calculated. did i miss that from somewhere??
also, what did you mean by different propeller? aren’t mine longer which means slightly more drag at idle cruise??
The cooling calculation is in the OP with my little doodle of the standard engine nacelle
As for the propeller, yes, a longer prop of the same pitch will have more drag when it is windmilling (in other words, being driven from the airflow over it, instead of by the engine). Different pitch propellers, however, will have dramatically different drag characteristics, with a coarse-pitch propeller producing less drag than a fine-pitch prop when windmilling.
Think of it like a car engine braking down a hill; the effect is more pronounced in first gear than it is in sixth gear.
Wow… I missed the first round because of 70-80 hour work weeks but there is way too much happy nerdage going on in this challenge for me to pass up next round. This looks to be an amazing type of challenge, well done @MrChips.
Congrats to the winner !
This is a very interesting challenge, and nicely hosted. I’ve learned a lot about airplanes and their engines!
Looking forward for the next one!
#Round Two - 4-Place Utility Single
After a successful first round, the second round of the Aero Challenge gets a little more complicated. The design brief is as follows:
Please completely fill out a copy of the REVISED Aero Challenge Powerplant Calculator - FOUND HERE - and download a PDF or save a screenshot of it…I need this information in order for my flight model to work!
Once you are satisfied with your engine, use the Export function in Automation to export your engine family and variant files, then send the ZIP file along with the PDF or screenshot of your Powerplant Calculator results to me via PM. The submission deadline for this contest is 2359 GMT on Monday, September 26th (7:59 PM Eastern Time, 0059 CET on Tuesday, September 27th).
Please submit your entries named as follows:
Engine Family Name: “AAC R2 (Your Username)”
Engine Variant Name: Your Choice
Good luck to everyone!
can I join in this challenge?
I don’t seem to have the ability to pm yet, but once i do i’ll send you my entry, I think it might be a bit unique.
Why wouldn’t you? Go ahead, make an engine!
yes. yes you can. it has just started
though, it is not the challenge i’d recommend to a newcomer as it’s more complex than just the game itself
I understand. I will read the rules and try to make an engine
I have no fucking idea how to design a plane but I won’t let that stop me!
okay. what’s the advantage of more propellers? i can’t see it via the calculator. it only seems to add weight, cost, power requirements,
Can I ask you how to make engine in this challenge,because I can’t understand anything.
Basically More prop blades = more surface area, so you can shift more air and thus move more mass.
yeah it need more power though, which means, the mass moving power is not because of just the propeller, but more because of the engine power available. which doesn’t really explain my question
More blades gives the propeller more lifting area, which means the propeller can absorb more engine power in a similar diameter, or the same power in a smaller diameter. This isn’t necessarily critical in this round of the competition but when we get into multi-engine aircraft, where prop diameter can be very limited due to ground clearance issues, it will absolutely become an important consideration.
And to all the new people asking; yes, by all means enter the competition…you’re more than welcome to do so! And while you’re at it, why not check out some of the other challenges here as well?
What is the target speed for a craft like this?
Oh…forgot about that. There isn’t a target speed for this challenge per say, but I would say you’d probably want to aim for 140-175 knots…exactly how fast is up to you! I should also mention that target speed becomes less relevant if you choose a constant-speed propeller; at that point it only becomes a factor affecting cooling drag.