PA-28 Archer Technical Information?
 

Hi,
Let me start by firstly apologizing if this has been posted in the wrong section, there are quite a few! I am an Aerospace Engineering (BEng) Student from the UK that is currently investigating flow separation control techniques and their application to GA aircraft. The study looks specifically on the wheel fairings (or Wheel pants) on the PA-28 Archer.

I need to reproduce these in 3D to allow me to CFD test them. However, dimensions seem to be an elusive holy grail! If anyone is able to help either with High Resolution Images or in any other way, it would be greatly appreciated!

I did a quick search on that very popular search engine using the search term "PA28-181 wheel pants" and found a multitude of images, after-market products and claims of up to 10 knots greater speed! In my experience though, these additional speed claims tend to be a little bit "optimistic" shall we say? We run a whole fleet of Archers with no wheel pants installed. Most of them will top out at 120-125 KTAS. If they had factory wheel pants, I believe we might get as much as 128!

Performance loss
 

There is a performance write down for removeing the wheel fairings, if my memory is correct it is about 3%.

This would put the numbers quoted by westhawk roughly in the ballpark.

If it's the -181 archer you are looking at, the external shap e is identical to the -161 Warrior II. Those are readily found at most GA airfields, and the odds are that if you phone in advance and ask, nobody will mind you going and measuring one up.

One warning however - most clubs operating off grass probably removed them long ago as a nuisance. So either you want to see if they have some buried in a cupboard in the back of a hangar, or a flying club with all hard runways and maneuvering surfaces.

G

Hi, thank you for your reply! I have tried searching online however the images that are returned are unfortunately not suitable to allow me to reproduce a close to life 3 dimensional model. The speeds are extremely useful! As they represent the actual operating speeds of the aircraft experienced by the user (Some manufacturers may "inflate" their values slightly.). Thank you very much this information has been extremely useful.

- George

Hi, thank you for your response! If as you say they are shared across the -181 Archer and the -161 warrior this will greatly increase my chances of finding the information I require! I was initially contemplating contacting airfields/owners/schools but was unsure how open they would be to allow this. Again thank you for your response! To the internet I go!

-George

Where in London are you ?

Hi,
Southeast London Near LCY

Hello George.

As someone who owns a 77 Archer the subject of wheel spats is one close to my heart as the pre 78 models had smaller spats and not the 'pants' common to most peoples impression of the aircraft. The difference is that the earlier ones are worth 3-4 knots and the full leg pants around 7-8.

If you would like me to forward the relevant performance graph from my POH I would be happy to do so. PM me an email address and I'll mail it over.

I used to have a PA28-161 that had spats, which I think were the smaller ones. I'd agree with the 3-4 knot decrement in cruise at about 70% power.

Vaguely close to LCY I'd try North Weald (North Weald Flying Group are nice folks and have a suitable aeroplane), Fairoaks and Booker.

If you get sufficiently desperate, drop me a line. I don't presently have access to a -161, but do have access to a -151 with spats at an airfield in the Midlands. I don't know how similar the fuselage and undercarriage are between that and the Archer however, I do know that the wings are different.

G

If you can get to Elstree I can get you to a plane to measure the spats up, in fact I think I have some in the Hangar

The -151, -161 and -181 have the same airframe.

Archer (181) is different firewall forward (engine, cowlings, spinner, prop). Back seats are different.

Early -151 had a different aileron set up with dropped hinges and linked to the rudder. Later -151 were identical to the -161 except the engine.

As others have said, earlier spats/leg fairings were much smaller and didn’t fully enclose the wheel or undercarriage leg.

Alternatively you may want to get in touch with the companies that actually design and make ( aftermarket) “speed” parts like
http://www.knots2u.net
http://www.loprestiaviation.com/speed-spats-1.html?___store=russian&___from_store=english

I’m sure they’ll be happy to help an engineering student.

I needed to replace the spats on the '78 181 Archer I owned. I got replacements which had been on a similar age 161 Warrior.

The mains were fine but the nose wheel spat did not fit as the Archer had a bigger tyre. The spat looked the same but there must have been subtle differences.

Good point, dont overfill, I forgot that one.

The nose wheel and tyre are different on the -181, it uses a 6” wheel and 6.00x6 tyre against a 5” and 5.00x5 on the -151/161.

Just a passing thought about nosewheel spats - they can have a marked tendency to reduce directional static stability and to increase rudder power. I'm not aware of this being a problem with the PA28, but it certainly has been on some other similarly configured types.

G

My apologies for the delay in replying, Christmas and all...!
Thanks that would be fantastic! However, I cannot seem to find any way of sending a PM (Maybe due to probationary status?)



That would be beyond helpful! It would be a case of organising a time and date. I would need to return to my university first to see if they have any newfangled metrology equipment that I can borrow to make life easy.

Thanks! I will be sure to drop them a line. However, you would be surprised how reluctant some companies are at sharing information even for academia!

A hint that may be useful. Investigate first

- the complexity with which your CFD modelling software can genuinely take the shape you want to model.

- what you can do with ESDU data sheets.

This should tell you how accurately you genuinely need to measure up the spats.

G