spitfireguy99

I recently built a Sig Hummer designed for an .049 and converted to speed 400. It is geared at 3.1:1 on an 8 cell nimh pack; weighs 22 oz ready to fly. I can't get it in the air successfully and I don't know why.
Can ANYONE help?
Wingspan is about 34" low wing, no dihedral.
Wing chord aprox 6"

Henke Torphammar

which cells do ou use? 22oz seem heavy, if this is a pylon plane I would rather try the sp400 directdrive with a GĂĽnther prop. trying to lighten it to 17-18oz. which I think is doable with a decent battery and without the gearbox and so on... maybe you have large servos or very long wires in the plane, all those small things adds up to many ounces. the little 400 can fly a plane like this but it needs to be light.

spitfireguy99

What is a good diameter prop to use for direct drive?

Henke Torphammar

5,5x4,3 Garupner CAM or equal APC

spitfireguy99

Thanks alot for the advice.
I think first I'm going to try a lighter battery, like you said, and if that doesn't work, I'll have to try setting the plane up as a direct drive.

I hope I can report success.
Thanks again[8D]

TheTick

What kind of nimh are you using? I would think that going to direct drive would make the biggest difference.

spitfireguy99

Currently I'm running 1050 mah nimh 7 and 8 cells.
Ithink I'm going to try some triple A cells

sabre1205

I have just bought the Hummer. My plans are for a sp 400, GP C10 Micro ESC and a Electricfly Lite-ploy pack.
I plan a direct drive. I have checked out the rpm of the .049 and the sp400 and the sp400 has a little higher rpm. And i agree with everyone else that weight is a big factor. You may also want to hand launch the plane.
9/15/2004 Construction Completed Airplane w/o radio and motor weight 9.25oz.

spitfireguy99

Currently, I have switched to a GWS 350/C drive motor with a 2 cell LiPoly pack. With an 8x6 prop, it flies very sluggishly, and won't turn without tipstalling. I also tried a 10x4.7 prop with little success.

My next thought is to add more wing area by adding longer wing tips, and If I have to, adding dihedral to the wing.

Obviously, this will affect the performance, but I'm willing to try it.

Also, I have only tried to hand launch the plane as I really have no place to make a good taxi run.

On the weight factor, I have reduced the weight to aprox. 17 oz from 22.

BuzzBomber

My Feedback: (4)

If that GWS 350 is a 'C' ratio (5.33:1), try a 9x7 or even a 10x8 gws prop on 2S lipo. Your best option to keep weight down and pitch speed up might be the 400 direct with a graupner 6x3 folder and 7 cells of KAN/CBP 650 2/3AA nimh. Run some options through [link=http://brantuas.com/ezcalc/dma1.asp]P-Calc[/link] and see what you get.

spitfireguy99

Thanks;

I've tried an 8x6 and a 10x4.7 props and they haven't done much, but I will try these sizes and see what I come up with.

I may also try going back to a direct drive.

khgiles

I was wondering about putting my brushless 400 motor on my hummer as well, and came across this post. Here is a picture of my hummer. I replaced the Wasp AP 0.61 with an OS 0.10 LA. I had to trim the fuselage off past the bulkhead to get the .10 on, but this plane screams with the .10 (note that I had to add about 1 oz on the tail to balance). I believe that this plane would not fly well with a GWS 350 as I have been flying these in a couple of the GWS kits (ME109, F4U), and the 350 provided only so-so performance. The ME109 and F4U only weight about 13 OZ, so the 22 OZ of the hummer seems too heavy. I put a brushless E-flite 400 motor in the ME109 and F4U and got very good performance (I believe it would hover with LiPo batteries, as I only have NiMH at the time).

I also have a house of balse P51 gas kit that I was wondering if I could fly with electric, but it weighs in around 22 oz as well. I am still planning on putting the OS .10 on the P51, after it's constructed.

Good luck with the hummer.

P.S. my hummer is a 17 year old kit that has been up in my attic, until I built it this past winter!

sabre1205

7/24/05 Construction complete. Plane weighs in at 20.5 oz with all equip on board
Will try to fly soon