RV7 Tail Wheel

The popular range of RV kitplanes

Moderator: Moderators

User avatar
Achim
Post Take off checks
Posts: 229
Joined: Wed Oct 11, 2006 12:59 pm
Closest Airfield: Gauteng
Has liked: 0
Been liked: 2 times

RV7 Tail Wheel

Unread post by Achim » Tue Jul 24, 2018 12:00 pm

Hi Guys

I have a RV7 with a standard Van's tail wheel, the aircraft has a IO-360 with a fixed pitch prop, this has given a very aft C of G and I need to limit my weight, specialty in the baggage area as the C of G will be outside the aft limit with two persons and very empty tanks.

I am considering the JDair tail wheel mod or the Van's lightweight tail wheel.
http://www.jdair.com/complete-tailwheel ... tail-link/
https://www.vansaircraft.com/cgi-bin/st ... LW-t-wheel

My question is to the RVers, has anyone in SA used the JDAir mod? This is certainly a mush better looking assembly compared to the Van's tail wheel.

The JDair and Vans light weight wheel will save about 1/2Kg, not much but might make a small difference.

Ciao Achim
User avatar
Chalkie
1k poster
1k poster
Posts: 1438
Joined: Mon Jun 02, 2008 9:19 am
Closest Airfield: FAPX
Location: In RV Eden.
Has liked: 34 times
Been liked: 129 times

Re: RV7 Tail Wheel

Unread post by Chalkie » Tue Jul 24, 2018 6:07 pm

Achim wrote:
Tue Jul 24, 2018 12:00 pm
Hi Guys

I have a RV7 with a standard Van's tail wheel, the aircraft has a IO-360 with a fixed pitch prop, this has given a very aft C of G and I need to limit my weight, specialty in the baggage area as the C of G will be outside the aft limit with two persons and very empty tanks.

I am considering the JDair tail wheel mod or the Van's lightweight tail wheel.
http://www.jdair.com/complete-tailwheel ... tail-link/
https://www.vansaircraft.com/cgi-bin/st ... LW-t-wheel

My question is to the RVers, has anyone in SA used the JDAir mod? This is certainly a mush better looking assembly compared to the Van's tail wheel.

The JDair and Vans light weight wheel will save about 1/2Kg, not much but might make a small difference.

Ciao Achim
I presume your IO-360 is 180 HP, parallel valve.

EDIT: This post has bugged me, because it is so wrong. Please email me all the values you have in your M & B as there is no way an RV-7 can be out the back of the envelope with just 2 people, no baggage and no fuel.

1. If you have a copy of your mass and balance, please send it to chalkboy at telkomsa dot net. There might be an error there.

2. If you have an electronic spreadsheet for your RV M&B, then play around with 3 or 4 kg of food, water, maps etc on the floor in front of the spar, the effect will surprise you.
Rule #2 Hurry up Slowly.
Cynic: One who knows the cost of everything and the value of nothing.
User avatar
Achim
Post Take off checks
Posts: 229
Joined: Wed Oct 11, 2006 12:59 pm
Closest Airfield: Gauteng
Has liked: 0
Been liked: 2 times

Re: RV7 Tail Wheel

Unread post by Achim » Wed Jul 25, 2018 1:29 pm

Hi Chalkie

Thanks for your reply, maybe I should rephrase "as the C of G will be outside the aft limit with two persons and very empty tanks"
With two people (160Kg total) on board and 20Kg in the baggage area, if I land with very empty tanks I will be close (but inside) the aft C of G limit.

As a rule, I fly with relatively full tanks, and don't intend landing with 10l each side and I limit the weight in the baggage area.

But when I do my flight planning I find the C of G more aft than I would like, therefor the question, would a light tail wheel make a noticeable difference or not? I use an electronic C of G calculator that I have sent to your e-mail.

I also want to justify spending USD600 on a better looking tail wheel :D

Regards
Achim
User avatar
Chalkie
1k poster
1k poster
Posts: 1438
Joined: Mon Jun 02, 2008 9:19 am
Closest Airfield: FAPX
Location: In RV Eden.
Has liked: 34 times
Been liked: 129 times

Re: RV7 Tail Wheel

Unread post by Chalkie » Wed Jul 25, 2018 4:57 pm

Achim wrote:
Wed Jul 25, 2018 1:29 pm
Hi Chalkie

Thanks for your reply, maybe I should rephrase "as the C of G will be outside the aft limit with two persons and very empty tanks"
With two people (160Kg total) on board and 20Kg in the baggage area, if I land with very empty tanks I will be close (but inside) the aft C of G limit. Regards Achim
OK. PM sent. So aft CG is close, but in limits...

If you stay within the parameters given by Van, then you will be quite safe as Van is an ultra conservative designer so do not worry if your landing is at close to published limits, besides three pointers are easier with an aft CG. (Less trim needed.)

If the CG movement of a light aircraft worries you, then rather than spend $600 on a shiny new tailwheel which will soon be covered in oil and dust; go to a local AMO and buy one of those great big Massey Furguson style starter motors and fit it in the place of your light weight rare earth permanent magnet unit. This will pull your CG further forward than the expensive tailwheel.
Rule #2 Hurry up Slowly.
Cynic: One who knows the cost of everything and the value of nothing.
User avatar
V5 - LEO
Six Tousand
Six Tousand
Posts: 6045
Joined: Mon Dec 05, 2011 4:18 pm
Closest Airfield: FYWH
Location: Namibia
Has liked: 63 times
Been liked: 55 times

Re: RV7 Tail Wheel

Unread post by V5 - LEO » Wed Jul 25, 2018 5:11 pm

Chalkie wrote:
Wed Jul 25, 2018 4:57 pm
If the CG movement of a light aircraft worries you, then rather than spend $600 on a shiny new tailwheel which will soon be covered in oil and dust; go to a local AMO and buy one of those great big Massey Furguson style starter motors and fit it in the place of your light weight rare earth permanent magnet unit. This will pull your CG further forward than the expensive tailwheel.
....this is the best practical advise I have encountered in a long while - kudos to you uncle Chalks =D>
In God I trust. The masses are never right, the minority are sometimes right, but the truth is always right.
“One good teacher in a lifetime may sometimes change a delinquent into a solid citizen.” — Philip Wylie
User avatar
Ugly Duckling
Six Tousand
Six Tousand
Posts: 6168
Joined: Sat Mar 18, 2006 2:24 pm
Closest Airfield: Brakpan Benoni FABB
Location: Waterkloof
Has liked: 302 times
Been liked: 227 times

Re: RV7 Tail Wheel

Unread post by Ugly Duckling » Wed Jul 25, 2018 6:46 pm

Chalkie wrote:
Wed Jul 25, 2018 4:57 pm
go to a local AMO and buy one of those great big Massey Furguson style starter motors and fit it in the place of your light weight rare earth permanent magnet unit. This will pull your CG further forward than the expensive tailwheel.
I'd rather up the battery capacity to 26 Ah from 16 Ah and keep the lekker starter.
Paul Sabatier EAA Ch 575, SSSA, ERGC, ERFC, AeroClub
Long time Cygnet builder
The object is to fly, it does not matter what the object is!
User avatar
V5 - LEO
Six Tousand
Six Tousand
Posts: 6045
Joined: Mon Dec 05, 2011 4:18 pm
Closest Airfield: FYWH
Location: Namibia
Has liked: 63 times
Been liked: 55 times

Re: RV7 Tail Wheel

Unread post by V5 - LEO » Wed Jul 25, 2018 7:12 pm

Ugly Duckling wrote:
Wed Jul 25, 2018 6:46 pm
Chalkie wrote:
Wed Jul 25, 2018 4:57 pm
go to a local AMO and buy one of those great big Massey Furguson style starter motors and fit it in the place of your light weight rare earth permanent magnet unit. This will pull your CG further forward than the expensive tailwheel.
I'd rather up the battery capacity to 26 Ah from 16 Ah and keep the lekker starter.
.....what is the weight difference UD, and is the location such to contribute to the achieved goal?
In God I trust. The masses are never right, the minority are sometimes right, but the truth is always right.
“One good teacher in a lifetime may sometimes change a delinquent into a solid citizen.” — Philip Wylie
User avatar
Chalkie
1k poster
1k poster
Posts: 1438
Joined: Mon Jun 02, 2008 9:19 am
Closest Airfield: FAPX
Location: In RV Eden.
Has liked: 34 times
Been liked: 129 times

Re: RV7 Tail Wheel

Unread post by Chalkie » Wed Jul 25, 2018 8:05 pm

Ugly Duckling wrote:
Wed Jul 25, 2018 6:46 pm
I'd rather up the battery capacity to 26 Ah from 16 Ah and keep the lekker starter.
Unfortunately that would require sheetmetal skills which some RV-owners do not possess, so a bolt on heavy starter motor is still my advice.
Rule #2 Hurry up Slowly.
Cynic: One who knows the cost of everything and the value of nothing.
User avatar
Ugly Duckling
Six Tousand
Six Tousand
Posts: 6168
Joined: Sat Mar 18, 2006 2:24 pm
Closest Airfield: Brakpan Benoni FABB
Location: Waterkloof
Has liked: 302 times
Been liked: 227 times

Re: RV7 Tail Wheel

Unread post by Ugly Duckling » Thu Jul 26, 2018 8:00 am

V5 - LEO wrote:
Wed Jul 25, 2018 7:12 pm

.....what is the weight difference UD, and is the location such to contribute to the achieved goal?
If you have the sheetmetal skills you have an additional 4 kg on the firewall. The battery can be mounted terminals parallel to the firewall then the footprint is virtually similar to the 16AH battery.
You do not have the required permissions to view the files attached to this post.
Paul Sabatier EAA Ch 575, SSSA, ERGC, ERFC, AeroClub
Long time Cygnet builder
The object is to fly, it does not matter what the object is!
User avatar
V5 - LEO
Six Tousand
Six Tousand
Posts: 6045
Joined: Mon Dec 05, 2011 4:18 pm
Closest Airfield: FYWH
Location: Namibia
Has liked: 63 times
Been liked: 55 times

Re: RV7 Tail Wheel

Unread post by V5 - LEO » Thu Jul 26, 2018 11:49 am

....uncle UD, maybe a simple question, but how long can the terminal cables be, I am thinking of the battery in a remote place and leads to motor, that way on the RV and the Cubby one can manipulate the CG a bit. I know it may not be ideal having these cables run long lengths where they may damage, but it sure can help?
In God I trust. The masses are never right, the minority are sometimes right, but the truth is always right.
“One good teacher in a lifetime may sometimes change a delinquent into a solid citizen.” — Philip Wylie
User avatar
Ugly Duckling
Six Tousand
Six Tousand
Posts: 6168
Joined: Sat Mar 18, 2006 2:24 pm
Closest Airfield: Brakpan Benoni FABB
Location: Waterkloof
Has liked: 302 times
Been liked: 227 times

Re: RV7 Tail Wheel

Unread post by Ugly Duckling » Thu Jul 26, 2018 12:20 pm

The RV-10 battery is in the back near the baggage bay so the cables can be any length BUT you then need to up the wire gauge to keep the volt drop on cranking to a minimum.
Any additional weight cuts into your payload. Will have to move the battery master relay as well and soon you have a whole new aeroplane :twisted:
Paul Sabatier EAA Ch 575, SSSA, ERGC, ERFC, AeroClub
Long time Cygnet builder
The object is to fly, it does not matter what the object is!
earthur
Avionics Master On
Posts: 67
Joined: Thu Apr 19, 2012 8:36 am
Has liked: 0
Been liked: 0

Re: RV7 Tail Wheel

Unread post by earthur » Thu Jul 26, 2018 4:24 pm

How about glassing some lead sheet onto the cowl is that an alternative ?

Arthur
User avatar
Achim
Post Take off checks
Posts: 229
Joined: Wed Oct 11, 2006 12:59 pm
Closest Airfield: Gauteng
Has liked: 0
Been liked: 2 times

Re: RV7 Tail Wheel

Unread post by Achim » Fri Jul 27, 2018 11:27 am

Hi Guys and thanks for the suggestions.

Part of building a light (in weight) aircraft is not to add useless weight, so my question is relay how to make the tail lighter.

Adding weight in the front will obviously make the situation better, but I don't want to add useless weight.

I have considered adding a second battery, I can buy the sheet metal from Vans, there is space and it will have a use and I don't need sheet metal skills and it can replicate the exact Vans installation, this complicates the electrics. A larger battery is also an option as UD mentioned.

I think adding a heavier starter has merit as it will be useful and add weight, probably even save costs, so I will keep this in mind. Thanks Chalkie

Adding lead is an option, but has no use.

There is also not much to gain from moving some avionics component from aft to in front of the C of G

BTW, I will not jump in and do any unconsidered and non engineered mods, it will be discussed with professional at the next annual.

Return to “Van's Aircraft”