Microlighters

Morning chaps,

We have an ASI problem on DBP. After the rebuild and subsequent flying, the Aquilla 2 was flying at 42mph IAS. This was too slow for this wing design but we left her at the current IAS to allow the new Dacron to stretch a bit. After 10 hrs, we tensioned the wing one notch further to get her flying a bit faster.

On Sat I put the GPS on and went "testing". IAS on the Skydat is now 43mph? This does not make sense....Downwind, I'm clocking 52knots on the GPS.... Turn around 180 and the ground speed decreases to 42 knts as I get the headwind. If I average these two out it means that out IAS should be much higher. Average GS is 47 knts which tells me that our IAS should be reading 54MPH Have I got this correct? If so it means that DBP was cruising closer to 50mph and the change we made to the wing tension was unnecessary?

I can only deduce that the Skydat is under reading? My Pitot tube does not point directly into the airflow during flight. I have been told by two AP's that this is not critical? My mind tells me otherwise....straightening it will require putting some spacers under the mount on one side. The tube leading from the pitot to the instrument is not blocked so I am really confused now. Should I go with my gut feel and improve the pitot angle?? Please help guys, an underreading ASI is not a great thing to have on board.

Bundy you clearly are not comfortable with the Pitot so fix it and get the right reading. You will be happier about it.

Get a mate to fly next to you at the same speed and compare readings.

Alan, I have a bird feed that is mounted on my training bar. You are most welcome to have a flip with this bird feed. I generally get around 53/54 mph on the DX2 and the bird feed is around 50/51mph, which I am happy that my DX2 is about right. Let me know when you are at ML and you can put it on your trike and test before replacing pitot tubes.

Thanks Klapperknop, that will be really useful just to confirm.

I suppose we have to acknowledge that the possibility exists that the Skydat was damaged (internally) during the prang? VSI accurate, as is the Altimeter but the ASI undereading really bugs me...I'm definately going to straighten the Pitot tube angle and see if this makes the difference. Currently it is pointing "up" and to the left in flight.

I'll be at ML on Sat...Stef will be in DBP but I'll be there for the braai for sure. Hope to see you there. We have yet to replace our training bars....will it be able to mount somewhere on the A frame?

Al

Alan, yip it can also go on the A-Frame.

I think fixing the angle of the pitot tube will make a big difference. My 2c, change the angle first and see if it makes a difference before going over to more complicated solutions

cheers