OK - gonna try the Cox Viper one more time.... - Page 4 - RC Groups
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Jul 10, 2001, 10:36 AM
Registered User
[QUOTE]Originally posted by frankenfoamy:
I pull 1.7 amps on 6 cells with the GWS motor.

Frankenfoamy, can you publish your test results? I'd sure like to know amp draw and thrust for the GWS direct drive with Viper prop at 6.0 V, 7.2 V, and 8.4 V.

Thanks!
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Jul 10, 2001, 02:26 PM
Registered User
Steve McBride's Avatar
I removed the little plastig jig from the wing and clear taped it flat.

I may have to pick up another one as the locak Wally-World has a bunch in stock now....

Have fun guys! Looking forward to some good flight reports!

Steve
Jul 10, 2001, 03:50 PM
Strange Plane Central
frankenfoamy's Avatar
The little plastic part in the wing helps to keep the plane from flying away. (gentle circles)counter acting torque is another purpose.
The DX GWS motor using the viper prop on 6 cells was 1.7 amps 11 watts 65 grams thrust.
7 cell NiMhd (double time 100s)
55 grams thrust did not measure current.

The 4.2:1 ratio geared N20 on 6 cells gave 35 grams thrust at one amp and 8 watts.
Extra pitch was twisted into the prop.
Jul 10, 2001, 09:55 PM
Registered User
Just finished my P-51 Mustang/Viper. Pictures here:
http://www.rusmart.net/download/StangPix.jpg

I added removable landing gear, which adds 3 grams and a bunch of drag to the RTF weight of 106 grams. I'm certain I didn't make my 100 gram goal because of paint, but I love the look and can't wait to see it airborne (windy here today).
Jul 11, 2001, 01:39 AM
AMA 697691 / FAA 13675
I got my Viper in the mail today! I went home for lunch and speak of the "devil".

I was impressed with how it looked right out of the box. This looks like a fun conversion. I'll be looking forward to reading all your tips as you test it out.
Latest blog entry: Greg's Web Hangar
Jul 11, 2001, 10:08 AM
Registered User
Pretty job on the Mustang!
Jul 11, 2001, 10:27 AM
AMA 697691 / FAA 13675
Nice job! You made it look too good before flying it though...i'd be afraid to fly it!

Since I have several other projects going, I'm gonna try free flying mine first before I "gut" it.

I'm not sure if I will go with a rudder or ailerons. Has anyone considered using the stock motor/prop/battery already in it?
Latest blog entry: Greg's Web Hangar
Jul 11, 2001, 11:39 AM
Strange Plane Central
frankenfoamy's Avatar
Quote:
I'm not sure if I will go with a rudder or ailerons. Has anyone considered using the stock motor/prop/battery already in it?[/B]
The M130 motor is is a current hog.
I ran it on 4 50 mah cells and they almost melted in 15 seconds! Also, you will need higher than two cell count to run non-exotic receivers and servos.
Jul 11, 2001, 11:51 AM
Registered User
I just got back from flying my Mustang Vipe for the first time. Looks like it'll fly well when I get everything figured out. On only about 2/3 throttle it climbed sharply with a soft launch. Trouble was, it kept pulling hard to the left, even with full right rudder. Wondering if I should have left that left wing adjustment where it was. My rudder deflection is minimal, maybe 3/16"... what kind of throws are needed? And what to do about the pull left?
Jul 11, 2001, 02:38 PM
AMA 697691 / FAA 13675
Mike,

Thanks for the response. I figured that there was an obvious reason not to leave it in there.

How do you feel about your rudder version as compared to your aileron version? Would it be easier for a less experienced builder to use the rudder conversion? Is the flight manuverability with the ailerons worth the modification?

rkissin,

It sure sounds like motor torque on your ship. Did you try a free flight glide and lower throttle flight?
Latest blog entry: Greg's Web Hangar
Jul 11, 2001, 02:59 PM
Registered User
motor offset, right thrust, for your thrust induced turn problem. 3 deg is pretty typical.
Jul 11, 2001, 09:10 PM
Strange Plane Central
frankenfoamy's Avatar
Quote:
Originally posted by Greg Covey:
[b]Mike,

How do you feel about your rudder version as compared to your aileron version? Would it be easier for a less experienced builder to use the rudder conversion? Is the flight manuverability with the ailerons worth the modification?
Rudder/elevator is easier to do. The aileron version lets you fight the wind easier and it rolls. (looks pretty cool doing it to!)
The aileron version also handles the motor torque problem easier. The one problem with the aileron version is that it is mandatory to stiffen the wings since you are cutting into them. This really turned out to be a good thing as the underchamber is not not so good at the increased speed the wingloading demands.

I do not recommend this as a trainer so a novice should not consider this until they have an aileron plane under their belt.

This is a real concern due to the cheap and cute factor. I have entertianed numerous questions from e-mails only to find out this was to be their first plane.
Jul 12, 2001, 09:37 AM
AMA 697691 / FAA 13675
Thanks again, Mike.

You have convinced me to try the aileron version. I have several 4-channel models and have much flight experience.

Where I lack the experience is in the subtle mods. needed to create stability in micro-flight. I had already acknowledged your expertise in this area and was also concerned that novice flyers may not appreciate this fact when blinded by the "low cost" factor.

I'm going to start this weekend by free flight testing the stock plane just to get a feel for it. I have still not decided wheather to use my geared 4:1 N20 motor or a direct drive G9330 motor with U80 prop.

Having the ability to roll this tiny plane is simply awesome! The "cute" factor of doing that at some e-shows will be great fun.

I'll follow your Web site instructions as close as possible.
Latest blog entry: Greg's Web Hangar
Jul 12, 2001, 12:03 PM
Registered User
Flight Report #2

Corrected thrust and flew again this morning. First I tried a six cell NiCd pack. At full power handling was touchy, had to back off. Got in a good flight but trim was off (so I though, more on that in a second) and I wound up plowing into a walkway, the only pavement for 100 yards in any direction. Thinking that flying was over for the morning, I went over to pick up the pieces and found there was only a minor scratch in the paint on the bottom of the nose! So this plane is surprisingly durable as well. Next I tried an 8 cell NiMh -- and I swear it was overpowered! This flight made me realize the the Westek LS-2.5 servos, while extremely light, are simply too slow for this plane -- making control unnecessarily difficult. So I guess I'm going to go with the GWS servos and sacrifice weight (probably on the order of 7 grams).

I second the opinion that this is not a good project for a first timer... even though the cost factor is minimal. Not in the "slow flyer" category.

MIKE: Do you see a way to drive the rudder off the aileron servo for coordinated turns? that would be AWESOME!
Jul 12, 2001, 02:31 PM
Registered User
I'm thinking of gluing some carbon fiber on the wing saddle and also extending the spar to the tip. Perhaps gluing/taping some very light carbon fiber rod along the LE. Heavy armor for those strafing runs .