Wheel Pants or No Wheel Pants

Purely from an esthetics point of view, do you think the RV-12 needs wheel pants?

From what I have read, the aircraft is on the edge of exceeding the LSA maximum cruise without. But it would depend on what Van?s philosophy is RE: ?120 Knots at Continuous Power ?. The LSA rules state ?at sea level?, which would translate to higher cruise speeds at altitude.

Each manufacturer seems to have a different point of view. Sonex, as an example, is LSA compliant with a Jabiru 3300. The Jabiru factory states that continuous power is 2750 rpm, yet the 3300 will run at 2950 to 3000 all day long. They claim a top ?cruise? of 170 mph in this rpm range. They are pushing the cruise speed to the limit. That appears to be their philosophy. Others seem to limit their cruise to 120 knots at altitude. I wonder how Van?s Aircraft looks at it.

Mike

Since the prop pitch is adjustable, having less drag means that meeting the speed limit will result in better take off and climb performance because of the lower pitch on the prop. I voted for wheel pants.

For Looks AND Efficiency

ABSOLUTELY!

In addition to aesthetics (in which, I think most agree the 12 needs a bit of help)...

Take her to the 120 Kts/138 MPH -at sea level limit! That is what LSA allows... give her all the speed the law approves. IF they find her a knot or two over, back off the prop a bit... and you gain some take-off/climb performance. These days, efficiency is becoming more and more important.

Honestly, I can't understand why any manufacturer wouldn't include pants... so someone here will have to explain why they wouldn't or shouldn't. I guess the only thing I would buy is if they find that somehow it jacks up their stall speed issue again. Overall, I'll be a bit disappointed if Wheel Pants aren't approved as part of the S-LSA/E-LSA package.

DJ

Some very good reasons for NOT having wheel pants:

1. Extra weight
2. Harder to check the air in the tires
3. Not a good idea for flying off of grass or dirt runways as they can collect dirt or mud and if cold can freze locking the wheel
4. Extra work when doing maintenance on the gear or the annual condition inspection.
5. They are not cheap to purchase and because they are light weight they need repairs most every year

Have a good day.

Best regards,
Vern

For wheel pants

I hope they are available for mainly one reason. I am very fussy, and I also fly off some grass strips in the area. Early morning wet grass makes a mess on the underside of the plane. That may sound like a small reason to some, but I like my plane to look nice at all times. Muddy tracks underneath just take away from any low-wing plane. Also not easy to lay underneath and clean it.

John Bender

wheel pants

Just one more issue to consider...Stability. They may not be very big, but you have 2 that are a little behind the cg, and one way out in front of the cg. How much will this affect the yaw stability?
One of those things worth considering.

vernhendershott said:

Some very good reasons for NOT having wheel pants:

1. Extra weight
2. Harder to check the air in the tires
3. Not a good idea for flying off of grass or dirt runways as they can collect dirt or mud and if cold can freze locking the wheel
4. Extra work when doing maintenance on the gear or the annual condition inspection.
5. They are not cheap to purchase and because they are light weight they need repairs most every year

Have a good day.

Best regards,
Vern

Click to expand...

Yes... I agree that those are reasons why a particular individual may not want them... but to me they are minimal or don't apply in my case. My question was more as to why would the manufacturer not offer them? They enhance performance and efficiency - which is a selling point for all aircraft - even LSA's. This is validated by the results of the survey.

DJ

Alan Gilmore said:

Just one more issue to consider...Stability. They may not be very big, but you have 2 that are a little behind the cg, and one way out in front of the cg. How much will this affect the yaw stability?
One of those things worth considering.

Click to expand...

Hmmm... I'm not an aircraft designer... but is this really a factor? I can't picture it effecting yaw. Seems like with most aircraft having wheelpants, the good must outweigh any bad.? I would defer to anyone else here with greater knowledge than I on this. DJ

If Vans includes them in the approved S-LSA, can they designate them as 'optional' for the builder of an E-LSA?

Phyrcooler said:

Hmmm... I'm not an aircraft designer... but is this really a factor? I can't picture it effecting yaw. Seems like with most aircraft having wheelpants, the good must outweigh any bad.? I would defer to anyone else here with greater knowledge than I on this. DJ

Click to expand...

Anything that has an aerodynamic effect on an aircraft can (not necessarily will) have an effect on flight characteristics. These can be wheel fairings, gear leg fairings, external pods, etc.

Some of the effects can be yaw stability, pitch stability, spin recovery, etc.
It is not automatic that anything added will effect the flight characteristics but particularly anything that is added fwd of the C.G. has the potential to have an effect. Think of it like this...anything added fwd of the C.G., particularly if it has side area like a gear leg fairing or wheel fairing, is the same as adding vertical fin area fwd of the C.G. This will subtract from the stabilizing effect that the aft stabilizers have.

It is the designers responsibility (you, if you are modifying someone else's design) to prove that spin recovery and general flight stability has not been degraded, etc.

I don't think many of us have the qualifications to do detailed spin testing at all C.G and flight conditions, so this should not not be done casually if Van's does not offer them.

As a side note...there are numerous after market gear leg and wheel fairings available to RV builders. Some of the gear leg fairings are quite a bit wider in cord than the standard kit fairings. When these are installed on a tail dragger they are fwd of the C.G. They have the potential to effect spin recover (I'm not saying that they do). Makes me wonder if anyone ever did any testing to see whether they did or not. My point is...it should make others wonder also...

I want wheel fairings.

wheel pants

Wheel pants (or something similar) would help keep stones, dirt etc from impacting the fuselage and the underside of the wing.

Fixed pitch

jamescone said:

Since the prop pitch is adjustable, having less drag means that meeting the speed limit will result in better take off and climb performance because of the lower pitch on the prop. I voted for wheel pants.

Click to expand...

I am a bit off topic, but Van's seems to now be talking about a fixed pitch propeller (on the red RV). Earlier they referred to it as ground adjustable. Am I missing something?

Rich