Trailers and wheel placement

Homebuilt Aircraft & Kit Plane Forum

Help Support Homebuilt Aircraft & Kit Plane Forum:

KeithO

Well-Known Member
Joined
Nov 29, 2009
Messages
868
Location
Jackson, MI
Given the car is surely the heavier of the 2 loads, the car should be in front of the axle, Then the plane behind it. That will tow the best. I would imagine that for something as fragile as an airplane that the trailer should be fully covered. When you get to your destination, you could remove the plane and car and have a pretty spacious "camper" for keeping out the weather.
 

PMD

Well-Known Member
Joined
Apr 11, 2015
Messages
1,182
Location
Martensville SK
Airbags give a soft ride, but bounce and bounce without shock absorbers. I wouldn't use them for a round Aus trip - we had an airbag trailer for work, and airbag troubles let it down more than once.

A Smart car weighs approx 850 kg, plus the plane, so that's say 1000 kg plus the trailer weight itself. That means you can get away with a single axle trailer.
I have an air suspended tractor that has had but one bag changeout in 1.8mm kms. If you are careful about mounting and plumbing, air suspension can be as reliable and far more durable than springs - not to mention a million times softer than rubber torsion axles.

The LAST thing you want with a light trailer and delicate load is a single axle. Two lighter axles ride far, far better than any single can.
 

PMD

Well-Known Member
Joined
Apr 11, 2015
Messages
1,182
Location
Martensville SK
Note: You'll want to also consider the weight on the trailer hitch/tow vehicle suspension after you've taken that car off the trailer (at the campsite, etc). If designed for the weight of a car, the trailer's wheels may be pretty far aft. You don't want to be in a situation where, after the car is downloaded at campsite, the weight on the hitch exceeds the weight permitted by the tow vehicle's receiver/ structure/suspension.
The solution to that is dead simple: put the car CofG right smack on the trailer axle(s) centerline so that the fully laden trailer puts 10-15% on the drawbar. When you offload the car, you will have exactly the same weight on the drawbar, so no change as far as the tow vehicle is concerned.
 

Vigilant1

Well-Known Member
Supporting Member
Joined
Jan 24, 2011
Messages
8,418
Location
US
The solution to that is dead simple: put the car CofG right smack on the trailer axle(s) centerline so that the fully laden trailer puts 10-15% on the drawbar. When you offload the car, you will have exactly the same weight on the drawbar, so no change as far as the tow vehicle is concerned.
That would work to address that problem-- removing the car won't change the weight on the hitch. But, putting the axle at the car"s CG AND putting that point where the trailer will have the right amount of weight on the hitch when full loaded is unlikely to simultaneously also result in allowing the most compact arrangement of internal items (which seems to be an objective). The details of the various weights will tell the tale.


I still like the scooters! ;)
 
Last edited:

Vigilant1

Well-Known Member
Supporting Member
Joined
Jan 24, 2011
Messages
8,418
Location
US
Given the car is surely the heavier of the 2 loads, the car should be in front of the axle, Then the plane behind it. That will tow the best.
I'm just guessing, but I'd think in a typical trip there would be more overnights where the car would be used than the airplane, so putting the car at the back avoids needing to download the plane whenever the car is needed.
Regarding towing manners: Especially during heavy braking it is best if there's not a heavy weight concentrated at the back of a long trailer (even if the wheels are in the right spot for CG purposes). OTOH, if the trailer brakes function correctly it should reduce the likelihood of a problem.
 
Last edited:

KeithO

Well-Known Member
Joined
Nov 29, 2009
Messages
868
Location
Jackson, MI
If the car is 8.5 feet wide, that is the maximum trailering width, but legal in the US. Would not know the rules in Oz. But that would allow the car be loaded sideways, which would also mean you could unload it independently of the airplane if/when needed.
 

Skippydiesel

Well-Known Member
Joined
Dec 15, 2021
Messages
72
My "Aircraft Carrier" started life as a 1975 Viscount Supreme Caravan -

Gutted the interior, which lead to body structural integrity issues. Fixed the wobbles by putting in 4 square tube ribs,at approximately equal intervals down the body interior. Re build front frame, using aluminium square tube, to increase body stiffness. Last rib double tube to take/hang the single rear door.

Floor all in 10mm marine ply except for wheel arch area which is in 15 mm ply.

Most glass windows broken - replaced glass with a clear double walled polly carbonate. All but one openable window mechanisms RS, so rivetted closed position.

Cut the rear body off at the chassis. Replaced with aluminium single door aluminium square tube and sheet aluminium, riveted together.

Put 24 threaded eye bolts down each side, through chassis outriggers, to secure aircraft components.

Passed roadworthy inspection on first go. Departed, same day, on 22 hr round trip to pick up my new Sonex project. Aside from built in head wind - towed like a dream.

Currently providing overflow space for Sonex project.

With the aid of copious quantities of marine caulking, now have a weather tight van that could be easily adapted to almost any boy toy use or even converted back to mobile human habitat.

Sonex due to be transported to airfield within next two weeks - will use the Aircraft Career to accomplish this.
 

rtfm

Well-Known Member
Joined
Jan 3, 2008
Messages
3,754
Location
Brisbane, Australia
My "Aircraft Carrier" started life as a 1975 Viscount Supreme Caravan -

Gutted the interior, which lead to body structural integrity issues. Fixed the wobbles by putting in 4 square tube ribs,at approximately equal intervals down the body interior. Re build front frame, using aluminium square tube, to increase body stiffness. Last rib double tube to take/hang the single rear door.

Floor all in 10mm marine ply except for wheel arch area which is in 15 mm ply.

Most glass windows broken - replaced glass with a clear double walled polly carbonate. All but one openable window mechanisms RS, so rivetted closed position.

Cut the rear body off at the chassis. Replaced with aluminium single door aluminium square tube and sheet aluminium, riveted together.

Put 24 threaded eye bolts down each side, through chassis outriggers, to secure aircraft components.

Passed roadworthy inspection on first go. Departed, same day, on 22 hr round trip to pick up my new Sonex project. Aside from built in head wind - towed like a dream.

Currently providing overflow space for Sonex project.

With the aid of copious quantities of marine caulking, now have a weather tight van that could be easily adapted to almost any boy toy use or even converted back to mobile human habitat.

Sonex due to be transported to airfield within next two weeks - will use the Aircraft Career to accomplish this.
Any chance of a few pictures?
 

dog

Well-Known Member
Joined
Dec 29, 2019
Messages
807
the tounge weight must never be negative
10% gross weight is a minimum for the hitch to work properly and with a heavy
long wheelbase tow vehicle the total load on the
rear axel is going to be what is critical for handling,and has nothing to do with percentages
 

PMD

Well-Known Member
Joined
Apr 11, 2015
Messages
1,182
Location
Martensville SK
Car needs to load longitudinally. To do so transversely would mean loading OVER the wheels/fenders Main goal should be to keep C of G not only ideal longitudinally, but as low as possible.
 
Top