Charlie Kellogg's TBM Avenger Build
04-26-2019, 03:54 AM
#3526
My Feedback: (15)
Join Date: May 2003
Location: Iowa City, Iowa (again!)
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Couldn't find any hard documentation, but I am pretty sure I checked balance both with wheels up and down.
I was using a "Vanessa Rig" to balance all my large models... and because the model is upright and suspended from the rafters, it was easy enough to flip the switch and retract the gear to see how or whether the CG was affected. As I recall, the CG was not greatly changed whether gear were either up or down on the Avenger.
I was using a "Vanessa Rig" to balance all my large models... and because the model is upright and suspended from the rafters, it was easy enough to flip the switch and retract the gear to see how or whether the CG was affected. As I recall, the CG was not greatly changed whether gear were either up or down on the Avenger.
05-03-2019, 11:00 AM
#3527
Okay guys,
Here's my quandary even after speaking to Chic and reading Noah's post.
So my friend and I tried to balance the Avenger today on an EZ Balancer and NO luck, wheels up or down we couldn't get it to balance
Using the 6-7/8" balance point on Charlie's plans and I think I remember the same dimension from and earlier post, the plane would either show tail or nose heavy with absolutely no level balance.
I know we balanced the plane in NY and it has flown but I am now at a totAL LOSS nd before our Friend Chic gets to my point of frustration I was hoping someone has an idea of what I M MESSING UP.
I far from being the brightest bulb in the chandelier but this should be easy even for me...
HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Thanks guys, I know someone out there has an answer
Larry
Here's my quandary even after speaking to Chic and reading Noah's post.
So my friend and I tried to balance the Avenger today on an EZ Balancer and NO luck, wheels up or down we couldn't get it to balance
Using the 6-7/8" balance point on Charlie's plans and I think I remember the same dimension from and earlier post, the plane would either show tail or nose heavy with absolutely no level balance.
I know we balanced the plane in NY and it has flown but I am now at a totAL LOSS nd before our Friend Chic gets to my point of frustration I was hoping someone has an idea of what I M MESSING UP.
I far from being the brightest bulb in the chandelier but this should be easy even for me...
HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Thanks guys, I know someone out there has an answer
Larry
05-03-2019, 02:34 PM
#3528
Okay guys,
Part 2 of the above ?, my friend who was helping me said he spoke to another friend who said if the mass was greater over the wing the plane should be balanced upside down. I just went through Charlie's instructions again and it doesn't say which way......
Larry
Part 2 of the above ?, my friend who was helping me said he spoke to another friend who said if the mass was greater over the wing the plane should be balanced upside down. I just went through Charlie's instructions again and it doesn't say which way......
Larry
05-04-2019, 12:47 AM
#3529
Hi Larry,
I think your friend's friend is correct. I do not know if you know about these digital meters which should make life simpler:
XICOY CG METER (SPAIN) - https://www.xicoy.com/catalog/index....6fc87938d3bf21
Video description -
DIGITECH (NETHERLANDS) - Fast & Curious - CG Wizard
Hope this helps.
Reuben
I think your friend's friend is correct. I do not know if you know about these digital meters which should make life simpler:
XICOY CG METER (SPAIN) - https://www.xicoy.com/catalog/index....6fc87938d3bf21
Video description -
DIGITECH (NETHERLANDS) - Fast & Curious - CG Wizard
Hope this helps.
Reuben
05-04-2019, 05:20 AM
#3530
Reuben,
Thanks for the info, really helpful.
I was watching a video on you tube that showed using postal scales and math but this seems so much easier.
Will have to wait until I pay off the wife for the EZ Balancer before I take out another loan and listen to her gripe about it for days.
It just seems strange that when my friend and I built this on the East coast it not only balanced but flew well.
Waiting to see what our other Avenger friends have to say.
Thanks again
Larry
Thanks for the info, really helpful.
I was watching a video on you tube that showed using postal scales and math but this seems so much easier.
Will have to wait until I pay off the wife for the EZ Balancer before I take out another loan and listen to her gripe about it for days.
It just seems strange that when my friend and I built this on the East coast it not only balanced but flew well.
Waiting to see what our other Avenger friends have to say.
Thanks again
Larry
05-04-2019, 08:13 AM
#3531
Weight & Balance
Larry,
Here is a simple explaination of the method to calculate CG [manually] using a bit of math and weight at the wheels of the aircraft...(copied from a post on RCSB)...
- posted by "Invertmast" -
I have been using this method for years on heavier models that arent realistically able to use the finger method and i wasnt going to build some hanging contraption yo have to store.
To get a more accurate version, you need to have a fixed Datum point at fixed location on the model. I typically use the forward most point of the crankshaft or spinner.
The model needs to be leveled and each wheel placed on a scale (or if you dont have 3 scale, 1 scale will do with 2 additional blocks the same thickness as the scale under the other 3 wheels).
Then a measurement taken from the fixed Datum point to the center of each landing gear (the axle). For your drawing, these would be Distance A and B.
The weight taken at all 3 wheels. So it would be something like:
Left main weight X distance A = moment A
Right main weight X distance A = moment A2
Nose/tail weight x Distance B = moment B
All of the weights would be added and all of the moments would be added.
This gives you the equation:
Moment Total / Weigh Total = CG location from Fixed Datum.
The FAA Weight and Balance Handbook does a great job of explaining it all in great detail. They also go through different methods of shifting the CG with various types of formula’s (this begins on page 24).
FAA Weight and balance handbook
Have a Blessed Day
George Waldrop
Here is a simple explaination of the method to calculate CG [manually] using a bit of math and weight at the wheels of the aircraft...(copied from a post on RCSB)...
- posted by "Invertmast" -
I have been using this method for years on heavier models that arent realistically able to use the finger method and i wasnt going to build some hanging contraption yo have to store.
To get a more accurate version, you need to have a fixed Datum point at fixed location on the model. I typically use the forward most point of the crankshaft or spinner.
The model needs to be leveled and each wheel placed on a scale (or if you dont have 3 scale, 1 scale will do with 2 additional blocks the same thickness as the scale under the other 3 wheels).
Then a measurement taken from the fixed Datum point to the center of each landing gear (the axle). For your drawing, these would be Distance A and B.
The weight taken at all 3 wheels. So it would be something like:
Left main weight X distance A = moment A
Right main weight X distance A = moment A2
Nose/tail weight x Distance B = moment B
All of the weights would be added and all of the moments would be added.
This gives you the equation:
Moment Total / Weigh Total = CG location from Fixed Datum.
The FAA Weight and Balance Handbook does a great job of explaining it all in great detail. They also go through different methods of shifting the CG with various types of formula’s (this begins on page 24).
FAA Weight and balance handbook
Have a Blessed Day
George Waldrop
Last edited by georgewaldrop; 05-04-2019 at 08:31 AM. Reason: Spelling
05-04-2019, 08:29 AM
#3532
WOW - Might have to wait until Xmas or my birthday to buy the Xicoy machine. Looks so very simple - put the model on the three discs, get the weight and CG status immediately. Looks like the going price is $300. Hummmmmmm, No one close to borrow the unit from, may have to try and weigh the Avenger by the Easy Unit before I try to rut down any extra money I can find to possibly buy of the Xicoy units. Heading for the couch to dig in-between the cushions then under the seats in the car. Smile. Chic
05-05-2019, 05:27 AM
#3533
Guys,
Thanks for all the tips.
Turns out one of the guys in the club borrowed the Xicoy balancer from another member and has graciously offered to balance the beast at the field on Tuesday.
Being Charlie's instructions say to balance the bird with gear up I will have to put it on the EZ Balancer when I get home to see what changes from gear down to gear up.
Chic, if you stop using Shirley's BR for 2 months you should have enough for the purchase, the downside is Shirley won't have nearly enough $$ to go to Nordstrom's for hours on end
The plane already comes in at 43lbs with about 2+ pounds in the nose so I can't wait to see what the Xicoy says to add.
Stay tuned
This is why trains are so much easier, they fall on the floor and you pick it up and no rebuilding LOL
Larry
Thanks for all the tips.
Turns out one of the guys in the club borrowed the Xicoy balancer from another member and has graciously offered to balance the beast at the field on Tuesday.
Being Charlie's instructions say to balance the bird with gear up I will have to put it on the EZ Balancer when I get home to see what changes from gear down to gear up.
Chic, if you stop using Shirley's BR for 2 months you should have enough for the purchase, the downside is Shirley won't have nearly enough $$ to go to Nordstrom's for hours on end
The plane already comes in at 43lbs with about 2+ pounds in the nose so I can't wait to see what the Xicoy says to add.
Stay tuned
This is why trains are so much easier, they fall on the floor and you pick it up and no rebuilding LOL
Larry
05-15-2019, 07:10 AM
#3534
Okay guys,
Here's the balance update.
Balance day got put off a week but finally got to do it yesterday.
We put the beast on the Xicoy scales and after many measurements by our friend it turns out that it was balanced a bit nose heavy and it flew great on the maiden 4 years ago.
Here is the diagram that our friend came up with, at 28% have to add just a little weight...
Still can't figure out why it wouldn't balance on the EZ Balancer... it's a puzzlement I tell ya.
Larry
05-15-2019, 09:55 AM
#3535
Larry - So happy for ya. I followed your lead and asked Shirley and daughter for an early Father's Day present. They agreed but needed time to gather their money. I smiled and they agreed to end of May. That gives me about 15 days to get the Avenger ready to weight and balance when the Xicoy will arrive. Wondering why the one measurement did not come from the front of the cowl but after reading the downloaded instructions, it only asked for a measurement from the mains to where you want the weight to go. I am thinking that the weight of the engine is taken into consideration with the weight readings on the main wheels. Can't wait but I have work to do. Started flying a large taildragger (Valiant) to prep for the Avenger. Will post soon. Chic
05-18-2019, 10:32 AM
#3536
Work Bench is cleaned off and the Avenger has returned. Flight batteries (Duralites) ordered and Ignition Battery ordered. Using a set of jet flight batter packs to check out all functions (controls, bay doors, retracts, etc.) before I start buttoning her up from the bottom. Turn it over and install canopies, etc. Hope I get the Father's Day gift "EARLY" to start the balance process. By the way Larry --- "JUST IN CASE" arrived and it was uplifting to say the least. Stay Well and Stay Safe My Brother. Chic
05-20-2019, 02:17 PM
#3538
Well of course $#%& happens. One of the blind nuts decided to push its way out. So I had to cut out a new larger section of the firewall, replace it with a new block with another blind nut or tee nut, depending on which coast you are on. Smile. Pressing on tomorrow. 
05-28-2019, 05:10 PM
#3544
Chic,
looks awesome.... love the kill switch which I don't have on mine. The old tried and true method of low idle and cutoff switch on transmitter.
What size engine, I'm only using a DA85
Larry
looks awesome.... love the kill switch which I don't have on mine. The old tried and true method of low idle and cutoff switch on transmitter.
What size engine, I'm only using a DA85
Larry
06-02-2019, 08:27 AM
#3547
Hey Guys - Need some help. The inboard corner of the right hand flap has curled upward. When sitting in the wing, it is curled down - concerned if this will affect flight characteristics. I am looking at about a 1/16" or more. How can I fix this guys? THANKS Chic
06-03-2019, 05:15 AM
#3548
Chic,
Sorry, having computer problems as I answered this yesterday...strange
My thought would be to mark the flap where it starts to curl with some tape and then carefully score with a #11 blade against a straight edge. Then I would weigh it down so it was flat and carefully fill with some epoxy though with the size of the plane I'm not sure if it would have any effect.
Engine start tomorrow and maybe maiden if my test pilot thinks everything looks good...FINGERS CROSSED
Did you get to start yours this weekend????
Stay well brother
Larry
Sorry, having computer problems as I answered this yesterday...strange
My thought would be to mark the flap where it starts to curl with some tape and then carefully score with a #11 blade against a straight edge. Then I would weigh it down so it was flat and carefully fill with some epoxy though with the size of the plane I'm not sure if it would have any effect.
Engine start tomorrow and maybe maiden if my test pilot thinks everything looks good...FINGERS CROSSED
Did you get to start yours this weekend????
Stay well brother
Larry
06-03-2019, 06:22 AM
#3549
Larry, we are again, on the same page - was looking to score an edge along where the curvature begins. Then, mix up epoxy/fine glass fibers and lay in the opening. Weigh down the corner until dry. About to head to the shop, will inform you of the results this evening. Thanks. Chic