Speedwing 400 MKII

[Sev Fontaine]

I just finished building the new Speedwing 400 MKII.
The build was pretty straightforward and took only 2 evenings.
I would have maidened tonight were it not for 30 km/h winds and drizzling rain.
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The specs are as follows:
Direct Drive Align 420LF 3200KV with 4.75 x 4.75 apc speed 400 prop
CC Phoenix 35 speed controller
3S1P Thunder Power 2100mah
HS-81MG servos (thanks FCloake)

I was not able to run this motor in PeakEff to predict performance. Enough data could not be found online for this motor. I decided to go with a 4.75 x 4.75 prop for now and will take some in flight data during the maiden flight. If the current is too high... i'll either cut down the prop to a 4.2 x 4.75 or go with a smaller prop altogether.

The theoretical top speed for this setup assuming 10 V under full load is 32000 RPM and 143 MPH. Actual values will be lower but should still be good for over 100 MPH top speed. At a wing span of only 32 inches... I better keep my eyes open when flying this one.

I'll give a flight report and some power graphs from my in-flight data recorder when I perform the maiden flight.

Until then..... On to finish covering my Yak-54!
:)

[Sev Fontaine]

No maiden yet... but I did get a static bench test done.
Here is the data.
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Max Current: 24.5 A
Voltage under Full load: 10.8 V
Max Power 271 Watts

This prop is stalled at this Rpm and airspeed. In flight data may be significantly different. We'll see....

The motor is said to be good for 25A so i might be able to squeeze a bit more out of it. I'll have to check temperatures after a hard run.

[Tom Hastie]

The theoretical top speed for this setup assuming 10 V under full load is 32000 RPM and 143 MPH.

Aw man... this means that at NEAT fair, you're going to be one of those "guys with the Zagis" who gets all insulted and flustered if you call them one of those "guys with the Zagis".

Yup... don't blink.

Sounds great for indoor combat though!

Tom

[cgroves]

I think you are gonna' need a bigger gym :D

[Sev Fontaine]

I maidened tonight in 20-25 km/h winds. I was really impressed with the ability to climb without power. On initial hand launch into the wind I was able to climb to about 30 ft and from there hit the power and really start climbing. I'm pretty sure this one will follow me wherever I go. It's nice and small but packs a real punch.
I flew 2 packs.. the first was with my thunder power 2100 3s and the second was with my cheap no name 1800mah 3s. On the first pack I only flew about 5 minutes and then landed to check temps. Everything was nice and cool. Even though I knew my pack was only half drained I switched it out for my 1800. It provided less power but that was to be expected. I'll post in flight data tomorrow for each flight.

[Sev Fontaine]

Here is the data for my maiden and second flight. My maiden flight was with a Thunder power 2100 3S... the second a no name 1800 12C 3S.
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Note that I cut power several times to perform some glide tests. This wing has excellent glide performance and could probably slope soar if I removed the motor/battery and replaced it with a small 2 cell for the servos/receiver.

I seem to be pretty hard on my batteries. I wonder if the PHX 35 speed controller's voltage cut off is working. It shouldn't be going below 9 volts.
I'll have to play with that a bit.

[Sev Fontaine]

I've been flying this plane for the last few weeks now. Probably a good 15-20 flights a week. Yesterday I received my 2 new packs (lipower lites 3s 2100). I head out to this big dirt field next to an arena. The space is so big you could probably land an airliner. I load up one of my new packs and start flying. About 4 minutes into the flight I get a really bad glitch on a high speed pass causing the plane to roll left and up elevator. It performed a spiral nose dive at about 80 MPH into the hard packed dirt. As I get close to the crash site I see the pack about half crushed so I very carefully and quickly disconnect it from the speed controller and set it aside thinking it's going to catch fire. I then proceed to inspect the damage. Other than the broken top front spar the damage is very minimal. You have to love this EPP foam. Anyway, I then wonder why the lipo hasn't caught fire yet so I go looking for a way to destroy it. I find a nice big chunk of pavement with nice ragged edges and start throwing it at the pack. I must have hit it 10 times before giving up. It just wouldn't burn up so I get in the car and line up my front tire with the pack. I hit the gas, the tires start spinning and I run over the pack. Still no flames so I try again... and again... and again. By this time I start thinking if it hasn't burned up yet then it probably won't. I get out of the car and find the 3S pack separated in 3 separate and very mangled cells.
Lesson to be learned here.... don't waste your time / gas trying to blow up damaged lipos without the proper tools. (Mental image of a large fire to chuck the lipo in and wait for it to blow)

When I got home I started looking for any clues why I got such a severe glitch. I find the receiver antenna cut about 1/2" from the receiver. (Berg 4L has a very small gauge wire). No wonder I lost signal!

[Sev Fontaine]

I've decided to take this opportunity and make a battery bay (embedded into the foam) to protect my batteries. This should reduce drag significantly resulting in better glide and higher top speed. Anyone have about a square foot of 2 mil coroplast I could have or buy to make the battery bay door?

[cgroves]

Here is the data for my maiden and second flight. My maiden flight was with a Thunder power 2100 3S... the second a no name 1800 12C 3S.
Wow, the no name battery doesn't look like it is holding the voltage nearly as well as the TP cells. I would think the CC cutoff should have kicked in. What is the cutoff set at?

[Sev Fontaine]

I had it set at 9V. That's why i'm thinking the voltage cut off wasn't working properly.
So it shouldn't be going below 9V at all then?

[miketoner]

.... Anyone have about a square foot of 2 mil coroplast I could have or buy to make the battery bay door?

Hi Sev,

sounds like you've been pretty busy :p I've got a small box about 1/3 full of 2.5 mm coroplast scaps. Tell me the dimensions of your hatch door I'll send you a big enough scrap sufficient for the hatch. Also tell me your address and I'll put it in the mail to you.

btw I've been enjoying your HP motor on my franken-toro (it's my avatar). Last week one person said it looks like a flying mecanno set, and somebody else said it was noisey. I had to agree with both comments :cool:

- Mike

[Sev Fontaine]

Thanks Mike

PM Sent

I really liked that motor too. Excellent output and sound!

[Tom Hastie]

...Lesson to be learned here.... don't waste your time / gas trying to blow up damaged lipos without the proper tools. (Mental image of a large fire to chuck the lipo in and wait for it to blow)

Don't you keep jumper cables in your car? Seems to me what you should have done was connected the output to your car battery.

From my readings, it seems that more explosive vent w/flame incidents come from over charging the packs than from physical damage.

I'm guessing that a 13.8V fully charged car battery might be just enough to make something cool happen :)

If I remember correctly, your car is a lease... so the battery is under warranty ANYWAYS:rolleyes:

Tom

[NormMonkey]

You could always stab the LiPo with a metal screwdriver (http://www.calmdays.com/showthread.php?t=726).

[Sev Fontaine]

After the Lipo incident I decided to embed the battery pack inside the foam. The pictures show the end result of milling using a handheld dremel. Not too bad if I say so myself. For a hatch I used some 2mm coroplast. (Thanks again Mike!)
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During this rebuild I found that the two front carbon spars had broken in the crash. To stiffen things up without adding too much weight... I purchased some yellow jacket (open weave fiberglass used for roof repairs) and some 3M super 90 spray on glue. I applied a thin layer of spray on glue directly to the foam and then stuck on a precut sheet of glass just like you would using covering material. I covered the wing in wax paper to prevent sticking to the beds and weighed down the wing in the beds for curing. The end result is a super stiff, pretty light, and crash resistant airframe ready for covering.
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[Sev Fontaine]

I started and finished covering tonight after work.
Ultracote Bright yellow bottom
MonoKote Metallic Blue on top with Bright yellow highlights
Red striping on bottom leading edge
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I decided to keep my old covering (pre-rebuild) on the elevons to save some work and I think it came out great!
I then installed the speed controller, cut out the cooling holes, checked the fit on the LiPo and installed some velcro on the door.
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I can't wait to re-maiden. I think it's going to be quite a bit faster without the drag of the battery and with nice undisturbed flow for the prop.