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Old 06-04-2021, 01:01 PM   #1
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Default Wheeled Landing Gear On Helicopters

IMSMC: This was never officially covered in the _CW_ rules.

Looking at helicopters with wheels, does the following look like an acceptable Unofficial Handling of the subject:

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1) Helicopters must have a minimum of three (3) wheel positions -- either one (1) forward and two (2) back, or two (2) forward and one (1) back. [In short: Trike, or Reversed Trike.] Helicopters *may* have four wheel positions, two (2) each forward and back. [In short: Like a car.] Each position must have at least one tire. A second tire may be mounted.

2) Tires used by each helicopter body type:
a) 1-Man and Small use car tires.
b) Standard and Transport use truck tires.

3) Wheeled Landing Gear decreases top speed by 10%. Mounting Wheelguards on all wheel positions cancels this speed decrease. [In short: Same rules as Airplanes and Microplanes.]

Explanatory Notes:

There have been four-wheeled helicopters -- the Westland Wasp, and Sikorsky S-55, to name two -- so I included four wheels as an option.

Tire sizes are based on cars of similar weights, which is why the Standard has to use truck tires.

---

Did I miss anything important?
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Old 06-04-2021, 05:22 PM   #2
swordtart
 
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Default Re: Wheeled Landing Gear On Helicopters

Since all helos with retractable landing gear use HD car tyres (specifically mentioned in Aeroduel, implied in CWC 2.5), why the requirement for truck tires? The logic perhaps is that as helos don't tend to taxi (rather than hopping) and they don't tent to perform rolling take-off or landing, the strain on the tyre is minimal.

Also unlike every other vehicle type (including other aircraft) the max weight of a helo is not entirely dependent on it's size (since you can cram a massive plant into a smaller helo and just pile on the armour (and EWPs etc).

However you could use the Aeroduel rule for landing gear requirements for different aircraft types by extrapolating from their maximum weights. I'd say under 10,000lb cycle tires, under 16,000lb car tires, above that truck tires.

EDIT:
What problem are you trying to solve? I take it this isn't so helos can move along the ground (other than taxiing - which doesn't really feature in CW). Is fixed undercarriage just to allow real-world styling (or realism - which isn't a really a factor in CW) or are you looking to provide some advantage?

Are you proposing to add the cost and weight of the tyres to the design. If so, how much are you discounting for the removal of the skids. Retractable undercarriage costs $1500 and weighs only 150lb and includes wheels and tires (in CWC2.5 at least). That is a budget of 50lb per wheel including the retracting motors Since retractable wheel guards cost $250 and weigh 50lb per pair (and 1 space) you could just take $375 and 75lb (and the 2 spaces) off the retractable undercarriage to establish the stats of fixed undercarriage (making it $1125 and 75lb including 3 HD tires at $300 and 120lb - so a net saving in weight at least over skids).

This might make fixed landing gear more attractive than retractable gear if you were permitting cycle tires on any type or going cheap by using Std tyres but in any other combination the retractable gear is a getter bet (and since it is generally under armour except when actually landing) it probably doesn't need more than HD tyres.

If you want to keep it simple, I'd just allow the fixed landing wheels to be direct equivalents of skids. They cost and weigh the same and have the same DPs, they are just cosmetically different.

As an aside the penalty to hit aircraft landing gear is surprisingly high though. If they are using standard wheels why is the to hit penalty so large?

Oh and a mini-skid/tail wheel is also an option (e.g. Sea King).

Last edited by swordtart; 06-05-2021 at 01:40 AM. Reason: Lots of stuff
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Old 06-04-2021, 08:34 PM   #3
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Default Re: Wheeled Landing Gear On Helicopters

I think metal caterpillar treads will help the helicopter traverse rough ground much better than wheels once on the ground ...
LOL
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Old 06-05-2021, 04:59 PM   #4
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Default Re: Wheeled Landing Gear On Helicopters

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Originally Posted by swordtart View Post
Since all helos with retractable landing gear use HD car tyres (specifically mentioned in Aeroduel, implied in CWC 2.5), why the requirement for truck tires? The logic perhaps is that as helos don't tend to taxi (rather than hopping) and they don't tent to perform rolling take-off or landing, the strain on the tyre is minimal.
You'd be surprised how often some helis undertake rolling takeoffs -- esp. in less-than-optimal takeoff conditions (high heat; high humidity; high altitude).

Taxiing is also an issue -- having helped roll around a skid-equipped heli on the little tires attached to the skids, the attractions of Proper Wheeled Landing Gear become apparent. :)

Cost and weight for tires vs. skids is effectively a wash -- the skids come off, but then there's the shocks, struts, etc., for the wheeled landing gear coming on; so the only addition is the tires themselves. (Fortunately, this also greatly simplifies the arithmetic.)

Helis being "odd" in that Maximum Load is wholly dependent on Power Factors (40' semi-trailers being the only other example of this), I went with car tires on the car-sized helis, and truck tires on the truck-sized helis, to prevent the phenomenon I kept seeing (and am guilty of myself) with micro- and airplanes of "always use the lightest-possible tires". Also: Looking at pics of helis, it appears the bigger the heli, the bigger the tire.

The bit about "helis with RLG have three HD tires" isn't really workable, esp. considering it applies as much to a 1-Man as a Transport; the Transport is going to squash those tires (23,000 lbs. on three tires, when most vehicles that heavy need at least six, and use truck tires).

Thanks for the input.
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Old 06-06-2021, 08:49 AM   #5
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Default Re: Wheeled Landing Gear On Helicopters

The whole tyre thing is a bit inconsistent anyway.

Consider that all the car bodies are stated to use a different size tyre (there are a couple of exceptions) but the tyres weigh the same. None of the other vehicle types specify this so we are left to guess whether the same rule should apply to them. Do all car trailers use interchangeable tyres (and which car are they interchangeable with) or are they all different?

There is also the issue that when we say tyres we are really probably talking about the wheels as well (since there is no information on what a wheel weighs or costs). This is important when you are taking about loss of a wheel vs loss of a tire.

IRL tyres are rated at a loading limit. This wasn't part of CW (and since it has a speed component this is probably just as well). I did try to implement a system where load limit was based on DPs but abandoned it as too much hassle given we already have the chassis load limit.

If memory serves I was using 250lb per DP (so a set of 4 Std tires could support 4000lb. Cars larger than a compact should really have better tyres than standard (though a 6 wheel chassis is an option). This also introduced the possibility of cascade failure where the loss of a tire overloaded the others so they also burst. Of course if you had better tyres than cheapo standards this would introduce a significant margin of safety.

Standard truck tires have 8 DPs and so can support 2000lb each this easily covers even an upgraded chassis for 10 wheel trucks. The largest bus needs to consider better tyres by default. In reality unless you are towing a full trailer half the weight of the semi trailer should be borne on the rear tyres of the tractor unit. Probably more than half of the weight of the cab is on the front wheels (since it can be far forward of the centre point) and so you should perhaps be using better tyres here as well, but this may be more complication than you wish.

CWC never specified what the tyres on the retractable undercarriage were (only stating they had DPs). It was Aeroduel that specified they were HD car tyres and that may have been a flawed assumption. Since the tires are included in the extra weight and cost these could be specific tyres to your particular airframe. Any weight difference can be hand waved in the same way that all car tyres of a type weigh the same despite supporting wildly varying chassis load limits.

Given you would need to change the existing ruling on retractable undercarriage to support a homebrew ruling, I'd just handwave the whole thing away. Taxiing or even rolling take off is a negligible ground component to driving your helo to the shops and back. It sounds like you are inventing a whole new game mechanic to cover a niche situation. There are better targets.

Last edited by swordtart; 06-06-2021 at 08:57 AM.
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Old 06-06-2021, 01:31 PM   #6
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Default Re: Wheeled Landing Gear On Helicopters

Quote:
Originally Posted by swordtart View Post
If memory serves I was using 250lb per DP (so a set of 4 Std tires could support 4000lb. Cars larger than a compact should really have better tyres than standard (though a 6 wheel chassis is an option). This also introduced the possibility of cascade failure where the loss of a tire overloaded the others so they also burst. Of course if you had better tyres than cheapo standards this would introduce a significant margin of safety.
I would expect the load limit to go down as DPs are lost.

(Because the game isn't slow enough…)
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Old 06-06-2021, 03:02 PM   #7
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Default Re: Wheeled Landing Gear On Helicopters

Quote:
Originally Posted by swordtart View Post
The whole tyre thing is a bit inconsistent anyway.
And that's what I was aiming toward -- while "foolish consistency is the hobgoblin of little minds", it's that first word which is the important distinction between whether something should be consistent, or not.
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Old 06-06-2021, 04:21 PM   #8
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Default Re: Wheeled Landing Gear On Helicopters

Quote:
Originally Posted by RogerBW View Post
I would expect the load limit to go down as DPs are lost.

(Because the game isn't slow enough…)
Indeed, but you can do a quick calculation in advance to see how many DPs in total you need to lose from your tyres before they burst under the strain. The tyre that bursts will be the one with the lowest DPs.

Of course you could just as easily argue that as the game stands, as long as you have at least 1 DP you can keep rolling along. It also presupposes that tyres in CW are inflated at all, if they were foam filled, the pressure wouldn't really matter. Are solids actually completely solid and/or are all tyres solid to a degree. If not you would expect solids to have a worse ride and have some HC penalty. Plasticores* are absolutely solid and they only get the HC penalty once the rubber (and therefore the grip) is gone.

This is why I abandoned trying to work it out. Too many unknowns. The juice wasn't worth the squeeze.

*Oh, now there's a thought, since the tyres on retractable undercarriage do not affect the helos HC when it is on the ground (since it doesn't have one), who is to say they aren't entirely made of armour grade plastic (it doesn't even need the rubber outer). It wouldn't matter then how much the helo weighed if that were the case.
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