qmdv wrote:

Glidergeek wrote:My dilemma is with the Pponk Super Eagle mod I'm doing it's supposed to add 45-50 lbs. that's all up front. I'm changing to the Lite wt. starter and the alternator loosing about 16 lbs with the 2. If I do the battery on the firewall I'll loose an additional what 20-25 lbs? With a net gain of 10-15 lbs but with a even more forward CG. Will 10 lbs in the tail counter the forward CG? And if you answer this today why aren't you out flyin, I've got an excuse

Not sure this got answered for you. Shorfielder has a 180 with a p-ponk and he has the Burl fire wall mounted battery. He just loves it. Send him a PM about it. I have his cell phone # that I would give you if you want. Send me a PM if interested in that.

I put a Burl box on my current 182B. I put an early version 182 Stol box in my previous 182B. Both good boxes. I have seen Bill's latest version and it looks real good. As far as the boxes themselves are concerned, I see no advantage of one over the other. Bill is a good guy IMHO. But then again, some think I am not.

Tim

We put in Version 1(like Burls ) in Tim's 59 182 probably 10 years ago. Were on version 3 now -Tim's ok just a little off center > right leaning .

qmdv wrote:. Shorfielder has a 180 with a p-ponk and he has the Burl fire wall mounted battery. He just loves it. Send him a PM about it. I have his cell phone # that I would give you if you want. Send me a PM if interested in that.

unfortunately, this is a good example of how hard it is not to compare apples to oranges...

Gary's 180 has a 88"C66 on it, and glidergeeks will have a 86"401 on it. The difference in weight saved on Garys prop more than negates the cg change we are discussing here. I believe splashpilot has an early 180/pponk/401. And if I recall correctly he said a while back that he runs out of aft trim on approach and actually holds back pressure to approach solo...(this is a pretty common deal with this setup) Fine for most folks, but not a flight characteristic I am particularly interested in, if avoidable. For me a light, early, 180/pponk would have to be either a 2 blade, or an MT. Since the 200 series props are a no go on the pponk, and the C58/C66 series are getting harder to find parts and pieces for, I will be going the MT route...

Rob

Matt 7GCBC wrote:So an aircraft will stall slower, and cruise faster with an aft CG.

Correct

Matt 7GCBC wrote:and usually cruise faster with less weight.

... not so fast, maybe yes, maybe no, really depends on how much weight, 'more' or 'less' is, and where in the cg that weight falls. Glider pilots are not carrying ballast to go slower...

Good catch, Rob. Thus the "usually". Also why I had to say no other weight loading variation. Wanted to keep the question as simple as possible.

Glidergeek, thanks for the link. The question remains, how much change in cruise and stall characteristics for a given CG change. Unless that was somewhere on the linked page?

Matt,

Just to throw something else into your consideration: Aft CG also lessens stability. That isn't a good thing, particularly in the back country, where predictable flight characteristics are essential.
MTV

182 STOL driver wrote:We put in Version 1(like Burls ) in Tim's 59 182 probably 10 years ago. Were on version 3 now -Tim's ok just a little off center > right leaning .

Almost correct. Your version one did not have a heat shield. Also Burl's box stands out from the cowl to miss the 180 sea plane kit cross brace. You version one is a good item I just wanted to clarify.

Tim

qmdv wrote:

182 STOL driver wrote:We put in Version 1(like Burls ) in Tim's 59 182 probably 10 years ago. Were on version 3 now -Tim's ok just a little off center > right leaning .

Almost correct. Your version one did not have a heat shield. Also Burl's box stands out from the cowl to miss the 180 sea plane kit cross brace. You version one is a good item I just wanted to clarify.

Tim

Version 1 was without front cover for heat in 180's. Heat shield was Version built in is 1a , Folded box for supercub and like is Version 2, Back plate mount is Version 3 ,Seaplane Mount Version 4 , 24-28 Volt is Version 5, I have MIL-Spec 100 drawings (FAA approved) drawings . I use SBS-J16 Batteries and make the cables(#2 and ends) in kit . Includes Battery,mount and box, Hardware ,Instructions and example of field approval in kit. With cowl off you can be flying within 1 hour .Need 90 degree drill ,#30 drill and blind riveter,stainless steel rivets from Aircraft Spruce(Sears hand riveter works well) gun and wrenches for terminals .Biggest part is taking old battery box out of back and removing cable. Firewall mounted battery box has been tested to over 30 G'S without deforming firewall . That's over 470 LBS hanging off of battery box.

"Glider pilots are not carrying ballast to go slower..."
We ballast only if there is going to be strong lift. In my glider I'll put 24 gallons in the wings (210lbs) & 1.5 in the tail (12.5lbs) for CG. My best L/D (50:1) is the same but at a faster speed I figure about 10kts. If lift is too weak I dump it.

OK, I'll put it in a context we can all appreciate, competition. Seeing everyone at Valdez this year with major mods to the plane and all out attempts to ditch weight got me thinking. Here is a competition where you are trying to land as slow as possible so as to stop as slow as possible while flying with one person up front. So the question is: Do you improve your aircraft for the competition by leaving the extra 20#s in the back to decrease your very forward CG OR do better by ditching the weight despite the resultant severely forward CG created??

Mike, no question on the poor stability qualities of the aft CG. As I discussed way back, its a no brainer mod when you're flying full weight. Loaded full I cruise with the trim full forward and the landings don't have as comfortable a feel when you are at aft CG - and the kiddos are only going to get bigger. Just trying to generate some hangar talk to get the brain pre-heated before starting the day.

My C170A with a O-360 Lyc, has the battery mounted on the firewall, right in the center behind the vacuum pump