Author Topic: New Impact XS (Read 10440 times)

Paul Walker · « **on:** April 07, 2010, 01:11:27 PM »

I have finished my new "Impact"....

This one is as much smaller than a standard Impact then the previous electric versions were larger. This one is 650 in^2. AR=5.25, and the wing thickness was also reduced. This is a significant change from all previous Impacts. The span is now 58.5". The weight is SIGNIFICANTLY improved at 61.8 ounces, ready for flight. Not bad for containing a 14 ounce battery!

The first flights were interesting. I took the system directly out of my test Impact, motor, timer, prop, ESC, etc. I left the settings the same. It flew at 5.3 sec / lap in the "normal" size impact. In the new plane, it went about 4.6 sec / lap. A very significant decrease in drag! Once slowed down to 5.2 sec / lap, it was very nice. I especially notice the better corner than the other electrics. So far, only 5 flights. The weather has been abysmal since, and I haven't flown it since. I am eager to work with it to make it a real winner. I plan on using it at the '11 Nats, so I have a few months to get it working right!

Wynn Robins · « **Reply #1 on:** April 07, 2010, 01:55:19 PM »

good style changes Paul!!! I like it!

I gather you are running A123 cells at 14oz - what capacity are they ?

Dean Pappas · « **Reply #2 on:** April 07, 2010, 02:27:43 PM »

Hi Paul,
It sure looks nice. How about some photos of the business end?
Is it a top-loader? side? and all that curiosity stuff.
Thanks,
Dean P.

Paul Walker · « **Reply #3 on:** April 07, 2010, 03:25:32 PM »

Quote from: Wynn Robins on April 07, 2010, 01:55:19 PM

good style changes Paul!!! I like it!

I gather you are running A123 cells at 14oz - what capacity are they ?

Thanks.
The batteries are LiPo's. 5S2P 4000 Thunder Power. Very light weight for the capacity!

Paul Walker · « **Reply #4 on:** April 07, 2010, 03:36:06 PM »

Quote from: Dean Pappas on April 07, 2010, 02:27:43 PM

Hi Paul,
It sure looks nice. How about some photos of the business end?
Is it a top-loader? side? and all that curiosity stuff.
Thanks,
Dean P.

Well, the picture would be a little messy. I have lots of stuff in there that is relatively new to me.
1) The safety plug. Now that I use it, I don't know how I did without.
2) I have a Shultze battery monitor (LiPo Dimatic) that monitors the voltage level in each cell and doesn't let it discharge below 3.6 volts. If a single cell drops below that, it will immeadiatly slow down and stop, allowing enough time to recover, and saving the battery and potentially the plane from damage. It weighs ~14 grams.
3) It also has the Kim Doherty timer/processor in the compartment.
This all makes for a bunch of wires at this time. Maybe some day I can find a way to eliminate much of that wiring.

It is still a bottom loader. I am a conservative structures engineer and am leary of removing structure on both the top and bottom of the forward fuselage. It also has to do with cooling. I have PLENTY of air passing by all this equipment!

The ESC is a Shultze 18.46F2B and the motor is a Plettenberg Orbit 20 series. I don't remember the exact kv of the motor in it.

Paul

Mike Palko · « **Reply #5 on:** April 07, 2010, 04:01:40 PM »

Paul,

It looks great and I'm sure it will fly even better. Before you fly again buy a CD with owl and hawk calls and play it during your flights!

It looks like you are stirring the pot with the wording on the wing.

Sent you a PM.

Mike

Igor Burger · « **Reply #6 on:** April 07, 2010, 04:19:44 PM »

I see we are going to learn a lesson how long the nose should be on a stunter

Matt Colan · « **Reply #7 on:** April 07, 2010, 04:37:16 PM »

Looks great Paul!!!!!!!!!!! I like the style change to the Impact!

Does XS mean Xtra Small?

Howard Rush · « **Reply #8 on:** April 07, 2010, 04:40:01 PM »

Quote from: Paul Walker on April 07, 2010, 01:11:27 PM

The first flights were interesting. I took the system directly out of my test Impact, motor, timer, prop, ESC, etc. I left the settings the same. It flew at 5.3 sec / lap in the "normal" size impact. In the new plane, it went about 4.6 sec / lap. A very significant decrease in drag!

Same prop and RPM? What was the battery drain when you were flying at 5.2?

Howard Rush · « **Reply #9 on:** April 07, 2010, 04:40:51 PM »

Quote from: Matt Colan on April 07, 2010, 04:37:16 PM

Does XS mean Xtra Small?

Excess electrickery

Paul Walker · « **Reply #10 on:** April 07, 2010, 05:06:59 PM »

Quote from: Igor Burger on April 07, 2010, 04:19:44 PM

I see we are going to learn a lesson how long the nose should be on a stunter

And this nose is longer than the last!

Matt Colan · « **Reply #11 on:** April 07, 2010, 06:21:21 PM »

Paul, I was looking close at the photo, and I saw that those leadouts, at least the rear leadout seems like it comes out all the way be the flap, and the front leadout around the middle of the wing. Am I seeing things, or is that how it actually is?

Mike Palko · « **Reply #12 on:** April 07, 2010, 07:49:33 PM »

Quote from: Matt Colan on April 07, 2010, 06:21:21 PM

Paul, I was looking close at the photo, and I saw that those leadouts, at least the rear leadout seems like it comes out all the way be the flap, and the front leadout around the middle of the wing. Am I seeing things, or is that how it actually is?

You're seeing the lines laying slack on the ground.

Paul Walker · « **Reply #13 on:** April 07, 2010, 07:51:23 PM »

Quote from: Howard Rush on April 07, 2010, 04:40:01 PM

Same prop and RPM? What was the battery drain when you were flying at 5.2?

It was around ~2800

At 4.7 it was ~3200

Paul Walker · « **Reply #14 on:** April 07, 2010, 07:53:24 PM »

Quote from: Matt Colan on April 07, 2010, 06:21:21 PM

Paul, I was looking close at the photo, and I saw that those leadouts, at least the rear leadout seems like it comes out all the way be the flap, and the front leadout around the middle of the wing. Am I seeing things, or is that how it actually is?

Yes, you are seeing things. The flexible cables are hanging down, and what you are seeing are the flying lines going out to the handle.

XS = Extra Small

Paul

Paul Walker · « **Reply #15 on:** April 07, 2010, 07:54:29 PM »

Quote from: Igor Burger on April 07, 2010, 04:19:44 PM

I see we are going to learn a lesson how long the nose should be on a stunter

I also looks short due to the angle of the photo. It really isn't terribly short.

Dennis Adamisin · « **Reply #16 on:** April 07, 2010, 09:23:19 PM »

MOST excellent! Great sounding numbers, scary (lack of) weight. That was a HUGE change in drag too. Am really hoping to make the NATs this year so I can see it..

Mark Scarborough · « **Reply #17 on:** April 07, 2010, 11:47:47 PM »

Paul,
are you coming to Portland next weekend? would love to gander at this one up close.
You mentioned thinning the wing, were you refering to the percentage, or just the scale down effect?

Warren Leadbeatter · « **Reply #18 on:** April 08, 2010, 03:48:17 AM »

Very nice!!! I want one.

Paul Walker · « **Reply #19 on:** April 08, 2010, 08:55:34 AM »

Quote from: Mark Scarborough on April 07, 2010, 11:47:47 PM

Paul,
are you coming to Portland next weekend? would love to gander at this one up close.
You mentioned thinning the wing, were you refering to the percentage, or just the scale down effect?

Portland,

? Maybe....Not sure, we'll see..

Thin...More than just a scale effect. It is 2.2 inches thick, as opposed to nearly the 2.5 of the Impact.

Paul

Paul Walker · « **Reply #20 on:** April 08, 2010, 01:12:38 PM »

That was a HUGE change in drag too. Am really hoping to make the NATs this year so I can see it..
[/quote]

I'll be there at the Nats this year, but not in a flying capacity!

Paul W

Claudio Chacon · « **Reply #21 on:** April 08, 2010, 01:29:30 PM »

IMPRESSIVE machine Mr. Walker. (and may be a bit "scary" too for those who will be contending in 2011...)
If it's not too personal, can you tell us more about the reason of the frase on the wing tip "Do You Believe it Now"?

Thanks and congrats!
Claudio
ARGENTINA

Paul Walker · « **Reply #22 on:** April 08, 2010, 04:37:33 PM »

Quote from: Claudio Chacon on April 08, 2010, 01:29:30 PM

IMPRESSIVE machine Mr. Walker. (and may be a bit "scary" too for those who will be contending in 2011...)
If it's not too personal, can you tell us more about the reason of the frase on the wing tip "Do You Believe it Now"?

Thanks and congrats!
Claudio
ARGENTINA

There are some who think that an electric stunt plane is NOT competitive at the top level. I intend to prove them wrong.

Igor Burger · « **Reply #23 on:** April 08, 2010, 04:45:11 PM »

psssst ... let them sleep further

Mike Palko · « **Reply #24 on:** April 08, 2010, 09:37:27 PM »

Ignorance is bliss!

RandySmith · « **Reply #25 on:** April 08, 2010, 09:41:53 PM »

Quote from: Paul Walker on April 08, 2010, 04:37:33 PM

There are some who think that an electric stunt plane is NOT competitive at the top level. I intend to prove them wrong.

Paul

I really doubt that very much, anyone that is serious knows that there has been electric ships finish very high at the Worlds and at the U.S Team trials..I even heard rumors we had electric ships on the U.S team

Randy

Paul Walker · « **Reply #26 on:** April 09, 2010, 12:45:29 PM »

I even heard rumors we had electric ships on the U.S team

Randy
[/quote]

Yeah...Except it failed (pun intended) to make the trip!

Paul W

Jim Pollock · « **Reply #27 on:** April 10, 2010, 06:01:20 PM »

Well Paul,

The Shrunken Impact has a really good new look to it! I like that Vertical fin.....Kinda reminds me of
the bigger All American Eagle.

O.K. You and Dave are all set to go get um at the WC's

1&2 Just don't know exactly which will be which yet, but with you tenacity. You could pull it off!

Jim Pollock

Bob Hunt · « **Reply #28 on:** April 11, 2010, 10:06:17 AM »

Well Jim, it would take a bit more than tenacity... It would take a miracle! Paul's not on the team this year... He took some time off to serve the Stunt community by volunteering to direct the Nats last year and this year. Wouldn't it be nice if all who achieve high success in this event would do the same occasionally?

Don't worry, however, as he will be back at a WCs in the near future I predict, and will take electric power to the pinnacle.

Bob Hunt

Paul Walker · « **Reply #29 on:** April 12, 2010, 09:19:33 AM »

I have now tried the prop that Dennis A generated. The APC 13 * 4.5, pusher.

I did a controlled experiment. First I made a 13 * 4.5 tractor from the very similar APC prop. Adjusted the speed to be about 5.5 sec/lap. Very nice performer and used less energy from the battery as well. It appears to be more efficient than the prop I had on it.

Then, I switched to the tractor. It flew at 5.4 sec/lap. I can see that I need to make a pusher prop pitch gage to compliment the tractor pitch gage. None the less, it was very noticable where it was "different" than the tractor. The takeoff, the outside turn on the horizontal eights, the outside portion of the vertical eight, the top of the hourglass, and the 3rd loop of the clover were all improved. I can see why some like it! I do see a decrease on the inside portion of the horizontal eights, but more testing in the wind is necessary to see if that is much of a problem.

All in all, I really like the APC props in this size on this airplane. I will have to try this pusher prop on the bigger planes to see if they work there as well.

Nice work Dennis in getting this prop to us!

Paul Walker

Steve Fitton · « **Reply #30 on:** April 12, 2010, 09:43:55 AM »

Those look like really huge flaps! (or maybe a trick of the camera angle)....

Dean Pappas · « **Reply #31 on:** April 12, 2010, 11:02:36 AM »

Glad to hear it, Paul!
How much less battery did you use?
Now we need to piece together a 3-blader using the same blades and do some limited testing before bugging our friends at APC for a new mold.
At least in Pattern, we foiund that their preferred mold base would at most accomodate a 13" 3-blader.

later,
Dean P.

Jim Pollock · « **Reply #32 on:** April 12, 2010, 12:33:53 PM »

Thanks Bob,

I apparently forgot that Paul didn't fly at the Team Trials this year..... Oh well, there's always year after next!

Jim Pollock

Paul Walker · « **Reply #33 on:** April 12, 2010, 12:57:17 PM »

Quote from: Steve Fitton on April 12, 2010, 09:43:55 AM

Those look like really huge flaps! (or maybe a trick of the camera angle)....

It must be an illusion. They are only 20% flaps..Clearly not David Fitz size flaps, but not PatternMaster size flapseither.

Paul Walker · « **Reply #34 on:** April 12, 2010, 01:01:29 PM »

Quote from: Dean Pappas on April 12, 2010, 11:02:36 AM

Glad to hear it, Paul!
How much less battery did you use?
Now we need to piece together a 3-blader using the same blades and do some limited testing before bugging our friends at APC for a new mold.
At least in Pattern, we foiund that their preferred mold base would at most accomodate a 13" 3-blader.

later,
Dean P.

Yes, sign me up for a test of the 13" 3 blader! I can't wait. A 3 blade pusher 13" prop! Yeah!!!

How much less....I was running about 2750 with the original prop. With the APC is is down to about 2250. Thats 82%...Quite a surprise it's that much to me.

Hope you enjoyed your party Sunday!

Dennis Adamisin · « **Reply #35 on:** April 12, 2010, 08:16:13 PM »

Hi Paul

THANKS for the feedback. I was hoping to hear that you had a chance to fly the pusher, especially when I saw the numbers on the new Impact - seemed like it would be a great match. That is a huge difference in power draw - I thought there would be some but not THAT much. Heck you gotta chance to downsize your pack and score a couple fewer ounces if you choose.

When we first contacted APC they were dead cold to the idea of a 3-blader, but I'd really like to try one of those too... Maybe Dean & the RC pattern guys can get us an in???

Mark Scarborough · « **Reply #36 on:** April 12, 2010, 09:34:52 PM »

Pssttttt.,
don't

tell anyone I showed this to you, its my total top secret setup lol,,
http://www.xoarintl.com/props/model-airplane/PJI-E.html
maybe they will flip the CNC machine language programing and mill a few pushers?

Mark Scarborough · « **Reply #37 on:** April 12, 2010, 10:22:52 PM »

Actually I emailed XOAR and asked about electric three blade pushers. here is the reply I got from them

*******
We have standard 13 x 4, 5,6,7,8 Price is $45/pcs tractor; $50 for pusher; Shipping & handling is not included;

However if you want to have 13 x 4.5, we can custom produce for you, there will be $100 tooling cost;

Those prop are considered as special prop, almost no dealer carries them, we will serve you on direct basis.
*****

so there is another option for you to consider.
Paul, if you want to see one of their props, I have several wood two blades, they are by far the prettiest wood props I have ever seen. every one I have opened has been balanced out of the package, and the finish is spectacular.

Dean Pappas · « **Reply #38 on:** April 13, 2010, 08:14:42 AM »

Hi Guys!
Yes, Paul ... We had a blast. You should have been there.
Thanks for the info: 18% wasted (

!!!) energy. I gotta ask, was it really wasted or was there some benefit we should know about for educational purposes.
Maybe more testing is needed to be able to say if that is so.

Fred and Otto at APC used to be very accomodating, and I am sure they lost money on some of the goose-chases they were sent on.
Fortunately my main RC experimenting buddy Lockhart and I have sent them down way more good paths than some of the demanding big-name guys.
I will try, but only after we glue/screw a 3-blader together from the existing APC blades (That's how Bobba went to England in '88!) and fly it on a testbed.

For $50 I'd order a pusher 3-bladed 13-5 from the XOAR folks. Expect maybe 7~10% more power consumption, but it'd be a great test.
If it works out well and APC never does make the 3-blader then you can thin the wooden blade airfoils and bag some carbon over them to restore stiffness.
later,
Dean P.

Mark Scarborough · « **Reply #39 on:** April 13, 2010, 08:47:32 AM »

Dean,
FYI, these props are pretty well thinned out already. They are very nice,, ( the electric ones especially so)
I should say, the two blades are, I havent stepped up to buy a three blade yet so I cant speak for them directly.

Howard Rush · « **Reply #40 on:** April 13, 2010, 09:24:53 AM »

At the cost of a prop and a half, one could make a 3-blade APC mold and crank out carbon copies.

Paul Walker · « **Reply #41 on:** April 13, 2010, 12:57:46 PM »

Quote from: Howard Rush on April 13, 2010, 09:24:53 AM

At the cost of a prop and a half, one could make a 3-blade APC mold and crank out carbon copies.

I'm glad to hear that you volunteered!

PW

Dean Pappas · « **Reply #42 on:** April 13, 2010, 01:09:44 PM »

WoW!
Thanks Howard ...

(dog pile on the rabbit! dog pile on the rabbit!)

Dean

Howard Rush · « **Reply #43 on:** April 13, 2010, 01:49:33 PM »

Has anyone measured chords and airfoils of these lovely props? If somebody does that hard part, I can do a little advance comparison between the 2- and 3-bladers.

Mark Scarborough · « **Reply #44 on:** April 13, 2010, 06:52:05 PM »

Howard,
are you going to be in Portland? I will bring them with me. well the two blades, I havent invested in the three blade yet..

Howard Rush · « **Reply #45 on:** April 13, 2010, 08:41:13 PM »

I'll try to be there, but I kinda doubt it.

I was thinking of the APC prop. If the others hold together and are available to buy for less than $100, they wouldn't be worth making just for an experiment.

NED-088 · « **Reply #46 on:** April 14, 2010, 05:40:43 PM »

Quote from: Dean Pappas on April 13, 2010, 08:14:42 AM

I will try, but only after we glue/screw a 3-blader together from the existing APC blades (That's how Bobba went to England in '88!) and fly it on a testbed.

You meant to say '78?

John Witt · « **Reply #47 on:** April 14, 2010, 08:26:37 PM »

Howard, I have a couple of them (13-4.5 EP), I'd contribute. Would it take two or three? Guess it would depend on how you slice up the hub to get a mold. Might be faster and easier to get a subscription and get APC to do it, like the Adamisins did. I'd buy a half dozen or so.

John W

Howard Rush · « **Reply #48 on:** April 14, 2010, 08:43:24 PM »

Two oughta do it.

Mike Scholtes · « **Reply #49 on:** April 14, 2010, 09:10:09 PM »

If I understand the direction of this conversation correctly you are discussing taking an existing prop from a manufacturer, cutting it up, and molding a new prop from the commercially made prop. Before doing anything like that I would seek permission from APC or whoever's prop would be used. There is a lot of proprietary technology in these items and a lot of R&D expenditures, which I imagine APC (for example) would not like to see pirated. If for no other reason than avoiding bad feelings I would check with the manufacturer of the original before putting this idea into practice. These processes and the unique results (the prop) are intellectual property that is protected by federal and state law.