Tail heavy?

[Stumpy]

Well, I installed fresh leaf springs and the Maule TW last night...put the soft steering spring on the left per instructions, geometry looks good.
I weighed both the new Maule and the old Scott and actual difference was 1.3 pounds. (heavier now).

So, just for grins I leveled her out and threw a reasonably good bathroom scale under the tail and it's at 72 pounds...now, depending on how accurate that scale is that seems kinda heavy to me. She trims well enough in flight but the tail never has just jumped up on her own on take off. No bricks in the tail either (checked)...I don't even have an obligatory 20 pounds of old wire back there like Hank had...no extra $ from the recyclers I reckon.

I'm not going to bother deeply analyzing earlier W&B calcs because frankly I haven't much faith in them relative to the airplane as it stands. They show her at 841 with 73 on the tail a couple years ago, but used 196" as a moment arm. I'm a little leery of my CG to be honest. Gonna fetch the certified scales tomorrow night and do a proper job. The old numbers were figured with a metal prop and she now has a wood Sensenich, along with other changes...She had a W&B in 1953 of 797 total with 60 on the tail using a 198" moment. I'm just gonna do a careful fresh one.

'46 BC12D, A-75 and wood sensenich, two wing tanks, two doors, dual brakes, no electrical, paint isn't all that heavy on her.

That being said she has this nicely fitted extended baggage compartment in the arse end...aluminum all the way around, even across the front. Still has the sling too. I have a feeling that it is going to be exiting the airframe for the time being. Any guesses on what it might weigh? :-) Handy for sleeping bags but I would prefer a happier CG. Even then I might end up rebuilding the Scott tw. We shall see how the magic numbers look tomorrow.

[Hank Jarrett]

Re: Tail heavy?

Your plane is a GREAT example of why I NEVER trust an old W&B! I would bet most of the mods that moved the CG aft are not in the logs or were listed as having no effect.
One thing was, the controls with aft CG SURE WERE NICE AND LIGHT! Also REALLY glad I never dis a spin in her while at aft CG!

Hank

[Stumpy]

Re: Tail heavy?

Hank,
Yup...assume nothing. Laziness is no excuse either. That being said the AP/IA that did most of the previous work is a known factor...and an "old timer" who is fair and really good to me and knows our birds (and this one). On the other hand he is the absolute opposite of anal, which I appreciate but MAYBE NOT in this case. Considering her weight I think the CG will be in limits, but close. She was flying "normally..." not overly responsive or nose-up, etc. Wash out might be off a little bit too and that could keep the tail down--and it doesn't stay "glued down" or anything like that, just doesn't act quite like I think it should.

Regardless I want to lighten things up (me too...no more biscuits and gravy this month)...would rather have fuel since the capacity is there. Not THAT much to remove though. The only "extras" in her panel are a ball and a little 8-day clock. The two wing tanks and brakes for the right seat add a couple pounds to be sure. Fuselage was done lightly in Stewarts, but the wings had been aerothaned and are a couple pounds heavier than need be.

Just an educated guess but I think the difference between the former metal prop and the current wood one, and that baggage compartment aft are obviously making a difference. Going to weigh with it in and then remove and weigh again since she'll be on the scales anyway. Move the elt as far forward as possible too. Vac the dust out of the tail...every ounce counts right?

Not concerned that she won't be within limits one way or the other. It's all an improvement, right? :-)

[astjp2]

Re: Tail heavy?

Well it was an improvement up until you put a maule tail wheel on it....I will take the extra pound or 2 for the scott 3200 or equivlant. I also measure the leading edge of the wings to the tailwheel center line, that way you have a true arm.

[Stumpy]

Re: Tail heavy?

Yup...gonna use that measurement this evening...earlier ones are too short by a couple of inches.

Just finished removing 18.7 pounds of .032" 2024 from my fuselage and moved the elt forward to behind the seat. "Unofficial" scale weight at the tail now just under 62 pounds. I'm in a MUCH better mood now. Fairly confident my CG will be in the happy place this evening, and I've got more available load for fuel.

[astjp2]

Re: Tail heavy?

Send me your scale weights and measured arms and I will plug it into my spread sheet and give you your W&B....Tim [email protected]

[woodmw]

Re: Tail heavy?

Na! Send the info to Hank and he can run it through his slide rule.

[Stumpy]

Re: Tail heavy?

Mike, Right! Nothing like doing it by hand the hi-tech 19th century way....actually I still use as sextant on the boat just for grins, so no room to talk here.

Tim, Thanks...would appreciate my work double-checked. That kind of thing isn't my favorite/best activity. Not going to get to the scales until tomorrow. Carefully leveled and measured...A hair under 197" with the evil Maule...looks like it would be right about 196" with the Scott 2000.

[astjp2]

Re: Tail heavy?

I used a good digital level ($49 at sears) and then compare left and right sides of the horizontal for front to rear level. The cross level (side to side) is the upper door frames from what I remember. I drop a plumb bob from each wing leading edge and then one from the tail. I also drop one from the front of the skull cap and compare how things align up on the floor. While you are at it, also put in on jack stands, pull the wheels and check the wheel alignment....I set the gear to 1/8" toe in at 18" forward of the centerline of the axel. You will be amazed how well your airplane will taxi when that is done. I also check how vertical the post in on the tailwheel and shim it so its vertical when taxiing. Tim

[Stumpy]

Re: Tail heavy?

Tim,
Yup...Had already done so...thinking along similar lines. Hopefully squared away. EXCEPT of course for the inconsistent weights we had on the scales. After a frustrating session with a Pober Pixie and the Taylorcraft I asked my brother for the papers on the scales. Haven't been calibrated since 2002...figures. So I moved them around, averaged things, and double checked the tail with a different scale. Better than nothing anyway. So, with the Maule tw on I'm at-

Mains: 751 lbs. 1.75 inches aft
Tail: 66 lbs. 197.00 inches aft

That's with all three tanks dry but 3.75 quarts (7.5 pounds) of oil onboard.
I have nice seat cushions but think I can take five pounds off of them by using lighter wood under them (3/8" ply now...sheesh). If I put the old Scott on I loose 1.5 inches and 1.3 pounds on the tail. Waiting on a bushing and some other bits and that will be happening in all likelihood.
Thinking the scales are reading a little bit heavy, particularly at lighter weights (figured that after messing around with some lead shot bags to confirm my suspicions), but at least I have a pre-calibration idea, within a couple of pounds anyway. At least I'm not way out past the limits on CG. On to the next task for now.

[astjp2]

Re: Tail heavy?

I need left and right mains and your email address. I have a load schedule that you can see what adding fuel, pax and baggage does to your CG. Tim

[astjp2]

Re: Tail heavy?

I can put almost 200 lbs in my big baggage and 2 fat people and still have a good CG, 500 over gross but good CG. Lets see the numbers and then you can decide a little better on what is going on. Tim

I attached a copy of a max loadout, I don't know what your fuel quantity is or where exactly the center of your baggage is currently, but this gives you an example of 24 gal fuel 240ish in people and 38lbs of baggage. Tim

[Stumpy]

Re: Tail heavy?

Thanks Tim----That's about what I figured too. For some reason I'm having trouble sending a PM. Email is [email protected]
Here's the numbers:

My left main is 377, right main 374, tail 66.

My extended baggage ran aft from the back of the seat 38" to the next diagonal brace, but I won't be re-installing it unless I return to a metal prop, or maybe will wait until I do a planned C-85 conversion. It looked nice but the more I think about dragging around empty almost 20 lbs of unneeded dead weight aft of my CG, the happier I am about removing it. Would rather have fuel.
So my baggage area now consists of the usual 50 lb. placarded fabric sling and two dowels behind the seat.

I have 12 gals capacity in the nose per normal and a 6 gals in each wing.

[woodmw]

Re: Tail heavy?

two dowels behind the seat.
.

Could you elaborate a bit about what this is?

[astjp2]

Re: Tail heavy?

Could you elaborate a bit about what this is?

Probably the ones that either hold up the seat sling or the baggage sling...