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Old Nov 03, 2005, 10:34 AM
Pro Horder
turbonut's Avatar
upland CA
Joined Dec 2004
7,658 Posts
Hey justin, sooo give me a idea what set up too use and I will try it in my Huck! She is getting a bit beet up and I think a new one is in order..Wich will make the old one a good test mule!
Scott
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Old Nov 03, 2005, 10:51 AM
Hooper, full throttle!
Tommy D's Avatar
USA, NY, East Islip
Joined Feb 2004
11,066 Posts
Justin

I just wanted to pop back in here for 1 more question/comment. Feel free to give me the works if Iím out in right field, so to speak.

When bench testing propís one thing Iím aware of is a stalled condition. In all my tests the prop is stalled and some might reason will act quite differently in flight. My club president has recorded a lot of inflight data and has told me time and time again I would be VERY surprised at his real world numbers vs my bench figures.

That said how much does a ďstalledĒ condition affect these EDF tests?

One again great thread, almost makes me want to build a F-86. Ill have to go wattage as thatís what I have in the closet!

Tommy D
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Old Nov 03, 2005, 12:56 PM
Watts your motivation
roccobro's Avatar
San Bernardino, CA
Joined Aug 2003
6,512 Posts
Scott- I think you have alot of options here. I'd try the Mk2 rotor first, then maybe a different motor and or batteries. As you have a feel for how the plane is, I'd suggest you trying out each step to see just where the fun to $$ tapers off. I have almost any combo for you to try before you buy if you wish.

Tommy- you bring up a very good point. I don't know the answer as I have no degree and I haven't splurged on a BNB flight recorder...YET! I thought about purchasing one (or an E-meter) for these tests but my "funding" only covered some spare rotors and the motors from Randy.

One indicator of a stalled condition would be an increase in rpms, but not an increase in current consumption. I believe it would also have some audible cues to it that would sound out of place other than the high pitch scream. Ducting design will play a huge role in creating/eliminating a stalled condition inside a plane. As for on the bench here, I don't *think* we have seen a stalled condition yet.

PaulDFJetman has an SR-71 that runs the 4200 himax on 5s on each side. His current draw is ~14 amps (static), while I recorded just over 20A. He said he has something like 900mm of ducting(!) contributing to his assumed stalled condition but once airborne it flies beautifully.

Under most conditions, an EDF does NOT unload in flight. BUT you cannot take into account for the ducting unless you "static" test the whole model in a wind tunnel This ductings effect on the fan can be compared to the Alfa Mig vs Saber airspeed. Same AUW and (almost) wingloading but the mig is 10+mph faster. Why? I am not sure but the outlet of the F-86 has some drag to it by design AND has a larger diameter opening (54mm vs 51). FYI, my outlet cone is at 53.5mm and Alfa recommends between 50-52mm in its Mk2 fan literature (but says 50-54mm in the Mk1 literature). Exhaust outlet airspeed (efflux) is determined by the FSA % of the outlet. Smaller hole (80-90%FSA)= faster speed, larger hole(90-100% FSA)=greater thrust.



Justin
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Old Nov 03, 2005, 01:00 PM
Watts your motivation
roccobro's Avatar
San Bernardino, CA
Joined Aug 2003
6,512 Posts
2025-4200 on 5s pictures






Are the images of the wattmeter dark to you guys? They look great when I take them, DL, then view them, but look dark when posted on RCG.

Justin

EDIT: Thanks Keven onthe screen capture. I just tried some other ways of copying and it worked. I think my comp is getting slooooow...
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Old Nov 03, 2005, 02:25 PM
SoCal, Year Round Flying!
bmiller's Avatar
Newport Beach, CA
Joined May 2002
5,745 Posts
Justin, the intake ducts are very different in the alfas.
Mig-15 intake duct is same size all the way back to the fan.
F-86 intake duct is round shape for approx 2.5" then goes to a rectangular shape to get over the wing saddle and under the cockpit/electronics shelf, then back to round 1/2 - 1" from the fan. And (I'll check tonite) I'm pretty sure it's smaller overall than the migs duct.
The exhaust duct sizes/shape seem about the same except the migs actually exits the airframe but the F-86s ends approx 2" inside the fuselage. Extending it will really benefit this edf.
Bruce
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Old Nov 03, 2005, 02:28 PM
Model Designer
keven64's Avatar
United Kingdom, England, Burnley
Joined Apr 2001
5,501 Posts
Glad you got it going...

Yep - you need to defragment !
That poor PC is ashamed that it's drives aren't going 58,380 rpm... and it's objecting...

Photo quality - Do you have Photoshop - to 'clean up' pictures before posting ?

20v ? That's getting high now... you'll be connecting two car batteries in series, next...

Keven.
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Old Nov 03, 2005, 02:55 PM
Watts your motivation
roccobro's Avatar
San Bernardino, CA
Joined Aug 2003
6,512 Posts
Bruce- Thanks, that helps alot for those F-86 owners looking to eek out every last mph before dropping coin for new motor and batteries. I'm a stickler for keeping things efficient and mods that can increase it (and are cheap!).

Keven- I'll give my photo program a whirl, after some more testing! AlsthoughI'm not to good at that stuff anymore, I forced myself to log all the data into a spreadsheet so as not to torture those who are looking for information. Too bad the "notes" section at the end is always cut off...

Justin
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Old Nov 03, 2005, 03:47 PM
Registered User
peterangus's Avatar
Blackpool, Great Britain (UK)
Joined Dec 2003
1,342 Posts
roccobro

I notice ,in your post #1, that one important parameter is not listed in your bench test results. Namely, efflux velocity.

I notice, also, that in post #78, we at last see some reference to speeds.

Do you have any data on efflux speeds and flying speeds ?
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Old Nov 03, 2005, 04:06 PM
who dares wins
like2fly!'s Avatar
London,England
Joined Apr 2005
1,853 Posts
Quote:
Originally Posted by roccobro
you cannot take into account for the ducting unless you "static" test the whole model in a wind tunnel This ductings effect on the fan can be compared to the Alfa Mig vs Saber airspeed. Same AUW and (almost) wingloading but the mig is 10+mph faster. Why? I am not sure but the outlet of the F-86 has some drag to it by design AND has a larger diameter opening (54mm vs 51). FYI, my outlet cone is at 53.5mm and Alfa recommends between 50-52mm in its Mk2 fan literature (but says 50-54mm in the Mk1 literature). Exhaust outlet airspeed (efflux) is determined by the FSA % of the outlet. Smaller hole (80-90%FSA)= faster speed, larger hole(90-100% FSA)=greater thrust.

Justin
peterangus

sorry to butt in but..
i think justin's tests are very usefull and they are all relative to each other, same conditions etc..
he doesn't have the actual models so maybe actual flight velocity would be another chapter
this is cool stuff, for me totally usefull!!!
thats why i was suggesting http://www.rcgroups.com/forums/showthread.php?t=423680 this is more stuff for the vault!!
Alex
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Old Nov 03, 2005, 04:19 PM
Permanently Banned
Joined Apr 2003
3,171 Posts
Good stuffs.

is it time for another chaper.
Put that power monster on a
flying model and fire it up.
Static test vs. dynamic test.

Since the alfa fan is designed for the alfa jets.
So put that 16/7/3, PQ 4s2p 1800, CC 60 (needed for 43 amps)
on the alfa mig 15 or F86 and fire it up
Anyone?

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Last edited by rcguy01; Nov 03, 2005 at 04:25 PM.
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Old Nov 03, 2005, 04:51 PM
who dares wins
like2fly!'s Avatar
London,England
Joined Apr 2005
1,853 Posts
Gooney, someone probably will , hey someone probably has
well me, im gona go for 16/7/4 and 4s TP prolite 2100, simply due to this thread! it will be better than the mp jet set-up i currently use which is Zzzz for me personally, this will give it a new lease of life

Alex
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Old Nov 03, 2005, 05:01 PM
Permanently Banned
Joined Apr 2003
3,171 Posts
nope, this monster please.
16/7/3, 4s2p, alfa fan on alfa jet.
The best power set up.
Still, anyone?



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Last edited by rcguy01; Nov 03, 2005 at 05:10 PM.
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Old Nov 03, 2005, 05:28 PM
Watts your motivation
roccobro's Avatar
San Bernardino, CA
Joined Aug 2003
6,512 Posts
Peterangus- Rpm and thrust can be converted to efflux by knowing FSA and outlet diam. I might be able to squeeze a calc function into the chart later. Give me some time as my daughter is home sick today. I have no way to do any fly speed tests or calcs. Others can calc efflux here themselves:
http://www.rcgroups.com/forums/showp...3&postcount=28
http://www.rcgroups.com/forums/showt...x&pagenumber=3

If Turbonut wants to take on of my the big dog setups for a run, I would not mind. Is it very easy to replace the whole fan unit in a completed model?

Alex- I really like your idea of the power info vault. Like in the Battery forum with their CBA charts and graph vault.

The TP PL's are rated for 50 amps burst so 4s1p pack would do for any of these setups, please everybody ignore the troll's posts

16/7/5 on 4s is done, 5s is charging and I am ammending the chart as fast as I can with a 30 pound lap weight clinging to me.

Justin
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Last edited by roccobro; Nov 03, 2005 at 07:26 PM. Reason: New spreadsheet capture *updated*
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Old Nov 03, 2005, 07:13 PM
Registered User
peterangus's Avatar
Blackpool, Great Britain (UK)
Joined Dec 2003
1,342 Posts
roccobo

When bench testing, you have the opportunity to measure efflux velocity. So why not do so ?

A database obtained from a variety of models might indicate some favourable relationship between efflux speed and flying speed.
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Old Nov 03, 2005, 07:37 PM
EDF rules... :)
AirX's Avatar
Joined Nov 1999
13,653 Posts
Thrust is a function of velocity and area giving volume and that volume is multiplied by the mass of air. We know the thrust and we know the area of the outlet just reconfigure the thrust equation to give the velocity.

Eric B.
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