Ducted fan aircraft

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by jthunt, Mar 17, 2012.

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1. Oct 14, 2019

Doggzilla

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“Us” refers to members who are grown adults and don’t try to turn everything into petty bickering. A group you are not a member of.

Testing different cruise settings is a normal part of testing and included in every Pilot Operating Handbook.

You would know that if you bothered to learn basic pilot skills instead of wasting your time making petty comments and trying to constantly start arguments in every thread.

2. Oct 15, 2019

Malish

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Our airplane was NEVER designed to compete with C-172 or 182, it's a different "animal". Our aircraft "burn" 58 liters(15 gal)/hr at cruise settings of 4000rpm and 90 liters(23 gal)/hr at max(TO) power at 5000rpm. What can you expect from 400hp engine?

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3. Oct 15, 2019

pictsidhe

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There aren't any particularly good books on ducted fans.
The aerodynamics of propulsion, Kuchemann and Weber is a general treatment of jet propulsion that is probably the most useful for the duct.

4. Oct 15, 2019

Vigilant1

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Your project is coming along very well (with a surprisingly small number of surprises!). You've been very up-front with the intent of the plane, with no unrealistic claims that a ducted fan will be more efficient than an open prop. Your plane is turning out to be what you promised--a great looking fun design that replicates many aspects of a tiny jet on a much smaller budget.

5. Oct 15, 2019

Malish

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It is not realy - ducted fan design based on different theory and it's different from jet propulsion - there, in ducted fan main Principe of thrust, is MASS FLOW.

Last edited: Oct 15, 2019
6. Oct 15, 2019

Malish

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At this power settings on engine(rpm's) this aircraft wouldn't fly very well. And for any reason we should use this power settings? If some one, who wants economy - let him buy C-172.

Last edited: Oct 15, 2019
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7. Oct 15, 2019

pictsidhe

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8. Oct 15, 2019

Doggzilla

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Well, there is an important reason.

If you can match 150mph at 11gph it means your fans can work with most common 200hp engines without losing performance.

It opens a very large market for your fans.

If you were spending $550,000 for a new aircraft, would you buy a Cirrus or Cessna, or would you buy a ducted fan that performs just as well? Most people would choose a ducted fan. 9. Oct 16, 2019 nicknack nicknack Active Member Joined: Jul 27, 2008 Messages: 27 Likes Received: 8 Beautiful aircraft, looks great. Malish... do truly get 400hp @23gal/hr? That works out to a BSFC of 23*6/400=0.345lb/hp-hr. That’s an incredible number..and is equal to 41% efficiency on par or rivaling the best Diesel engines. Maybe actual hp is less? 10. Oct 16, 2019 Doggzilla Doggzilla Well-Known MemberHBA Supporter Joined: Jun 2, 2013 Messages: 1,969 Likes Received: 414 Location: Everywhere USA It’s a 388hp LS6. It’s likely not running at full load because it’s not pitched for maximum speed and hits max RPM without full power. I’m 110% sure of this. And also 110% sure its capable of higher performance. Last edited: Oct 16, 2019 11. Oct 16, 2019 BJC BJC Well-Known MemberHBA Supporter Joined: Oct 7, 2013 Messages: 9,749 Likes Received: 6,531 Location: 97FL, Florida, USA I’m 100% sure that there is no such thing as 110% sure. (I’ve told you a million times to stop exaggerating.) BJC cheapracer and Terrh like this. 12. Oct 16, 2019 henryk henryk Well-Known Member Joined: Mar 8, 2010 Messages: 4,734 Likes Received: 459 Location: krakow,poland =many answers... 13. Oct 16, 2019 Malish Malish Well-Known Member Joined: Oct 11, 2013 Messages: 474 Likes Received: 778 Location: Russia. City of Volgograd You're right, right now engine is NOT developing 400hp. At TO throttle position the engine have max 4750rpm(our goal to have 5000rpm at TO settings) because the fan blade design and we're working on it to change that. Right now the engine developing about 370hp at max rpm(4750) according to the table of our engine test run on the dyno. Last edited: Oct 16, 2019 14. Oct 16, 2019 henryk henryk Well-Known Member Joined: Mar 8, 2010 Messages: 4,734 Likes Received: 459 Location: krakow,poland 15. Oct 16, 2019 Malish Malish Well-Known Member Joined: Oct 11, 2013 Messages: 474 Likes Received: 778 Location: Russia. City of Volgograd 16. Oct 16, 2019 Malish Malish Well-Known Member Joined: Oct 11, 2013 Messages: 474 Likes Received: 778 Location: Russia. City of Volgograd Compere it with our PJ-II "Dreamer" take off even not developing full power yet. Is there a difference in TO performance? henryk likes this. 17. Oct 16, 2019 Malish Malish Well-Known Member Joined: Oct 11, 2013 Messages: 474 Likes Received: 778 Location: Russia. City of Volgograd No, our aircraft can't do that and there no reason even talk about. Ducted fan is NEVER will be matching the performance of open prop aircraft with same size(power) engines. And our aircraft not costing$550,000 and for someone who wants something better than Cessna, will buy it.

Last edited: Oct 16, 2019
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18. Oct 17, 2019

Malish

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Ducted fan is not open prop - it's can't be pitched for maximum speed, like you do on propellers. Fan designed for max MASS FLOW(thrust) for power available from the engine. RPM's of the ducted fan stay the same - at static run or in the flight at any speed and this is proven on our airplane. When we push throttle for TO power before TO run - engine will rich max RPM's and they stay the same at ALL speed's, you can only reduce RPM's - to reduce power of the engine - retarding the throttle.
Today we did fly our airplane to check economy setting(that you asked for) to the engine - below 3500rpm airplane DON'T want to fly anymore without loosing altitude.

Last edited: Oct 17, 2019
19. Oct 17, 2019

Doggzilla

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Very interesting data Malish! Thank you for testing!

You may have just solved an old mystery.

The fan settings you just tried are similar to the MAXIMUM fan disk loading used on most western ducted fans.

Ducted fans which performed extremely poorly.

I will have to build a test drone to investigate further.

20. Oct 17, 2019

Lendo

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Malish, I like it!
Did you consider the Mazda Peripheral Ported Engine?
At 6,000 rpm is the engine is least stress with it 3:1 internal reduction the rotor itself is doing only 2,000 rpm, so at an even higher rpm say 7,000 it's still low stress. No inlet/ exhaust valves to restrict breathing, parts count are well down on a reciprocating engine. I know the Russians have used the Rotary Technology on many larger engines, but with the 2 rotor engine 200 + is very easy.
If weight was a consideration, consider replacing the Cast Iron 'End and Intermediate' housing with something lighter.
Just a suggestion!
George