HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Dec 17, 2012, 08:53 AM
Gopher huntin' stick jockey
turboparker's Avatar
East Bethel, MN USA
Joined Jul 2009
11,954 Posts
Quote:
Originally Posted by kalmon View Post
I thought about this as well but how well do inrunners brake? I know there is some significant torque differences from the outrunners that most electric conventional prop planes use.

On my down-lines I usually use about 1/3 to 1/2 throttle increasing throttle as I roll out to level flight.

-Brian
Brian,

Good point. On the other hand, an EDF rotor also has a much smaller moment than a typical prop, so I'd think it would also generate a lot less windmilling torque than a conventional prop that absorbs the same amount of power. Regarding the braking force of a windmilling prop - it is my understanding is that a spinning prop with a low pitch-angle (even when not connected to a motor or engine) has approximately the same drag as a solid disk of the same diameter, while a stationary prop's drag is a function of the flat-plate area of the blades & hub - as seen by the airstream. However, I was recently reading some work that shows this is pitch-dependent: http://www.peter2000.co.uk/aviation/misc/prop.pdf

3.2 Drag Force vs. Pitch:
The data for the drag force versus pitch were taken using the Master Airscrew set of propellers. The wind velocity was held
constant at about 5 m/s. Figure (7) shows that the drag force decreases with an increase in pitch. It also shows that at lower pitches
there is more drag on windmilling propellers and at higher pitches there is more drag on propellers held stationary. This crossover
point occurs around a pitch of 4.5. The question of which has more drag now depends on at least the pitch of the propeller.


BTW guys - my comments about EDF throttle-management consisting of nailing it until it's time to land was based on watching guys fly EDFs at the local field - not how I typically fly! I usually pull the throttle back to around 50% on down-lines, and then roll the power on as she pulls out of the bottom.

Not much MiG wx around here nowadays. The club field & road aren't plowed during the winter, and there isn't enough room around here to fly her from the street. It's pretty much down to flying the CC on floats from the yard & flying helis from the deck - unless we get the big midwinter melt.

Joel
turboparker is offline Find More Posts by turboparker
RCG Plus Member
Last edited by turboparker; Dec 17, 2012 at 01:28 PM.
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 17, 2012, 09:18 AM
Canadian Bacon
flypaper 2's Avatar
Kingston, Canada
Joined Jun 2004
12,903 Posts
I still do come in with throttle on, on all my EDFs and planes., simply because of the, throttle controls altitude and elev, controls speed aspect whether belly landings or gear landings.

Gord.
flypaper 2 is online now Find More Posts by flypaper 2
Reply With Quote
Old Dec 17, 2012, 01:03 PM
Do you see what I see?
rcoconut's Avatar
Rancho Cucamonga, CA
Joined Sep 2006
1,739 Posts
Quote:
Originally Posted by kalmon View Post
This is probably the best mod.


Other than than exactly what Joel said, move the elevator and rudder control horns in, get a good battery and fly.

-Brian
Sure am glad I did this mod!!!

Did a hand launch & the battery came out, she was still connected but dangling by the wires! Of course with aft CG she gently nosed up with a high angle of attack, her left wing dropped, and she fell right over, landing on all 3 wheels.

Inspection showed BOTH Horizontal Stabilizers cracked from along the Leading Edge almost all the way to the Trailing Edge The only thing holding 'em on was the CF flat stock!!!!

Thanks to Eastcoast & Pugsam for pictures of this mod!!!!

I used CA & Kicker for the repair & she's good to go!!!

p.s.- I didn't do the CF going thru the Vertical Fin, I placed my CF just after of the leading edge and just ahead of the Elevator, as well as placing a piece of CF on the ELE, I'm sure it's a bit more weight but I can't tell when I fly??
rcoconut is offline Find More Posts by rcoconut
Last edited by rcoconut; Dec 17, 2012 at 01:07 PM. Reason: words added
Reply With Quote
Old Dec 18, 2012, 12:11 AM
This thing runs real nice...
Nam Lemmi's Avatar
Joined Jun 2012
277 Posts
Quote:
Originally Posted by RealGambler View Post
How cold was it when you flew? Hyperions are great in the cold. I had mixed results with some 1S MA batteries in the cold (never bought 2S MA, so cannot say anything about those).
Temperature would have been around 25 Celsius. Remember these were just WOT engine runs on the floor at home and not actual flights.
Nam Lemmi is offline Find More Posts by Nam Lemmi
Reply With Quote
Old Dec 19, 2012, 12:33 AM
Yea, I fly dusty planes..
zeezee's Avatar
United States, LA, Angie
Joined Apr 2009
2,052 Posts
I was thinking about buying one of these and saw the big rudder discussion, the 1st plane I owned only had a rudder and elevator and was weird getting used to flying it. I know rudder. My son still flys my ole weedhopper, slow go-kart with wings.......Dave/zeezee
zeezee is offline Find More Posts by zeezee
Reply With Quote
Old Dec 19, 2012, 08:09 PM
Registered User
Valkpilot's Avatar
Joined Mar 2012
703 Posts
Quote:
Originally Posted by turboparker View Post
Brian,

Good point. On the other hand, an EDF rotor also has a much smaller moment than a typical prop, so I'd think it would also generate a lot less windmilling torque than a conventional prop that absorbs the same amount of power. Regarding the braking force of a windmilling prop - it is my understanding is that a spinning prop with a low pitch-angle (even when not connected to a motor or engine) has approximately the same drag as a solid disk of the same diameter, while a stationary prop's drag is a function of the flat-plate area of the blades & hub - as seen by the airstream. However, I was recently reading some work that shows this is pitch-dependent: http://www.peter2000.co.uk/aviation/misc/prop.pdf

3.2 Drag Force vs. Pitch:
The data for the drag force versus pitch were taken using the Master Airscrew set of propellers. The wind velocity was held
constant at about 5 m/s. Figure (7) shows that the drag force decreases with an increase in pitch. It also shows that at lower pitches
there is more drag on windmilling propellers and at higher pitches there is more drag on propellers held stationary. This crossover
point occurs around a pitch of 4.5. The question of which has more drag now depends on at least the pitch of the propeller.


BTW guys - my comments about EDF throttle-management consisting of nailing it until it's time to land was based on watching guys fly EDFs at the local field - not how I typically fly! I usually pull the throttle back to around 50% on down-lines, and then roll the power on as she pulls out of the bottom.

Not much MiG wx around here nowadays. The club field & road aren't plowed during the winter, and there isn't enough room around here to fly her from the street. It's pretty much down to flying the CC on floats from the yard & flying helis from the deck - unless we get the big midwinter melt.

Joel
Got a similar problem here in Pa, but snow hasn't set in yet. My usual field is closed, but did find a nice soccer field with a bit of pavement and monday flew
the MiG(with it's usual high standard of performance) inbetween the raindrops.
The only concern I have is in landing and takeoffs is guardrails. But I my just have to put her away and just fly my Sensei until the regular field opens.
Then I'll maiden my XB-70.
Valkpilot is offline Find More Posts by Valkpilot
Reply With Quote
Old Dec 19, 2012, 09:43 PM
Registered User
Joined Dec 2012
6 Posts
This first one is a 3S crash flying at dusk. I should know better lol.

EFlite UMX Mig 15 DF 3S flyby and Crash (1 min 14 sec)


This one is a more successful 3S flight braving turbulent winds gusting to 30mph!
Love this little thing! This was after previous crashes.

UMX Mig 15 DF 3S Windy (1 min 39 sec)
Xero187 is offline Find More Posts by Xero187
Reply With Quote
Old Dec 19, 2012, 09:47 PM
Registered User
United States, TN, Jackson
Joined Mar 2007
4,019 Posts
I'm glad that I got this discussion going about throttle management......

Think about this---Frontal area and drag...If you were to block off the nose of the MiG the appeared frontal area would go up significantly...This is the same thing as shutting down the throttle completely...The air backs up at the nose causing the same thing as if you just put a plate across the intake...

Now, think of what would happen if you opened up the throttle a little---This would relieve the pressure at the front of the plane just like removing the plate across the intake...The air pressure is relieved at the nose---Instead of a high pressure area causing drag you now have low pressure at the nose relieving the drag...This is what happens when you add a touch of throttle on the downlines...The fan stopped in the duct will cause an obstruction---And high pressure at the nose---The fan moving will cause a low pressure at the nose, reducing drag...Although there is drag in the duct, advancing the throttle should reduce the drag in the duct to create a low pressure area at the nose...Hence reducing frontal area drag and increasing the downline speed slightly...After all---We are taliking about a plane that weighs ounces...

Kevin
Kevin Greene is offline Find More Posts by Kevin Greene
Last edited by Kevin Greene; Dec 19, 2012 at 10:03 PM.
Reply With Quote
Old Dec 19, 2012, 10:29 PM
Registered User
Joined Dec 2012
6 Posts
Forgive my ignorance. What is a down-line? I'm a pilot a of a couple decades and have not heard this term?
Xero187 is offline Find More Posts by Xero187
Reply With Quote
Old Dec 20, 2012, 07:11 AM
Jagd Flieger
Sabastian's Avatar
Canada, ON, Mississauga
Joined Apr 2011
200 Posts
Hi guys

My wife purchased the Mig-15 as a Christmas present for me, I looked at it before she wrapped it up and I was wondering what is the best way to put the battery in the battery tray, I put the battery in with the balancing lead cable facing forward( towards the front of the plane) but there seems to be a lot of cable there to put back in the battery tray, do you guys just stuff the cables back in behind the battery? Also is the velcro strong enough to hold the battery in or are you guys using anything else to hold it in.

Thanks Sabastian
Sabastian is offline Find More Posts by Sabastian
Reply With Quote
Old Dec 20, 2012, 07:27 AM
The Luftwaffle
Waffleman's Avatar
United States, FL, DeLand
Joined Sep 2012
1,210 Posts
Velcro worked fine for me... And my TP 250 packs dont even have velcro, they just go in with friction. (I jnow thats gonna come back to bite me one of these days...)
Waffleman is offline Find More Posts by Waffleman
Reply With Quote
Old Dec 20, 2012, 07:38 AM
I'd rather be flying
baddb1's Avatar
United States, NY, Saratoga Springs
Joined Jan 2009
1,256 Posts
Quote:
Originally Posted by Sabastian View Post
Hi guys

My wife purchased the Mig-15 as a Christmas present for me, I looked at it before she wrapped it up and I was wondering what is the best way to put the battery in the battery tray, I put the battery in with the balancing lead cable facing forward( towards the front of the plane) but there seems to be a lot of cable there to put back in the battery tray, do you guys just stuff the cables back in behind the battery? Also is the velcro strong enough to hold the battery in or are you guys using anything else to hold it in.

Thanks Sabastian
Yeah, the velcro worked fine for me with over 40 flights on it. I face and stuff the wires in toward the rear. Enjoy the new Mig!
baddb1 is online now Find More Posts by baddb1
Reply With Quote
Old Dec 20, 2012, 09:25 AM
Parkzone junkie
kalmon's Avatar
United States, MI, Grand Traverse
Joined Oct 2008
3,659 Posts
Quote:
Originally Posted by Kevin Greene View Post
I'm glad that I got this discussion going about throttle management......

Think about this---Frontal area and drag...If you were to block off the nose of the MiG the appeared frontal area would go up significantly...This is the same thing as shutting down the throttle completely...The air backs up at the nose causing the same thing as if you just put a plate across the intake...

Now, think of what would happen if you opened up the throttle a little---This would relieve the pressure at the front of the plane just like removing the plate across the intake...The air pressure is relieved at the nose---Instead of a high pressure area causing drag you now have low pressure at the nose relieving the drag...This is what happens when you add a touch of throttle on the downlines...The fan stopped in the duct will cause an obstruction---And high pressure at the nose---The fan moving will cause a low pressure at the nose, reducing drag...Although there is drag in the duct, advancing the throttle should reduce the drag in the duct to create a low pressure area at the nose...Hence reducing frontal area drag and increasing the downline speed slightly...After all---We are taliking about a plane that weighs ounces...

Kevin
Kevin, if you have less throttle than required for that speed of flight the prop will still be creating pressure in front of the prop disc. Completely stopping the prop or setting a power level >= the speed traveling is the only way to reduce the frontal drag of the inlet area. This is all pretty much academic as we're talking about a 2 1/2 oz foam micro with a 30mm fan.

Downline = flight towards the ground. Think 2nd half of a hammerhead or 2nd half of a loop.

-Brian
kalmon is online now Find More Posts by kalmon
Reply With Quote
Old Dec 20, 2012, 09:26 AM
Gopher huntin' stick jockey
turboparker's Avatar
East Bethel, MN USA
Joined Jul 2009
11,954 Posts
Quote:
Originally Posted by Xero187 View Post
Forgive my ignorance. What is a down-line? I'm a pilot a of a couple decades and have not heard this term?
'Down-line' & 'up-line' are standard full-scale & RC aerobatic terms that describe the vertical segment of a maneuver.

Joel
turboparker is offline Find More Posts by turboparker
RCG Plus Member
Old Dec 20, 2012, 09:35 AM
F18
Registered User
United States, MA, Onset
Joined Apr 2008
233 Posts
Quote:
Originally Posted by Xero187 View Post
This first one is a 3S crash flying at dusk. I should know better lol.

https://www.youtube.com/watch?v=VcGI...e_gdata_player

This one is a more successful 3S flight braving turbulent winds gusting to 30mph!
Love this little thing! This was after previous crashes.

https://www.youtube.com/watch?v=wWt_...e_gdata_player
Great video! Good to have a pit crew doing the camera work. I use a hat mounted Epic camera,,,,,,,,I never realized how spastic my head movements are while flying this Mig.....It makes me motion sick to watch my vids.

Great rugged little jet! It's the "oh sh..t" moments at speed that make it exciting!
F18 is offline Find More Posts by F18
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Official Eflite UMX Beast Owners thread! darksiede Micro Ready-to-Fly 18429 Oct 14, 2014 02:13 PM
Discussion E-flite UMX MiG 15 DF SNEAK PEEK! D PAYNE Micro EDF Jets and Power Systems 2222 Oct 10, 2014 05:15 AM
Discussion Hobbyking Lancaster official owners thread Tartago Electric Warbirds 979 Aug 10, 2014 11:58 AM
Discussion UMX Mig-15 DF Mod Thread NitroCharged Micro EDF Jets and Power Systems 1132 Aug 01, 2014 04:30 PM
Sold Eflite F-86 Sabre 15 DF NIB! blue7.62 Aircraft - Electric - Jets (FS/W) 1 Apr 05, 2012 01:35 PM