McDonnell's XP-67 carried a conventional pitot static probe on its left wing leading edge, but something different on the opposite side. I can't find anything like it in aviation supply catalogs of the period, and I'm wondering if anyone recognizes what it's for? The spherical basket seems very odd.
Odd probe on XP-67
- Thread starter OldGeezer
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cvairwerks
Staff Sergeant
Probably an early system to keep a dynamic pressure probe aligned with the air flow. Sorta like the seeker heads on GBU's
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- #4
That's the Wylam drawing, isn't it? It shows a probe on the LH wing too, shorter than the one on the RH wing, but unlabeled. The Karlstrom 3-view has it on the RH wing as well, with nothing on the LH wing. There was actually an Army/Navy standard pitot static probe on the LH side in addition to the odd one on the RH side. It seems odd to have 2 sources of information coming in to a single airspeed gauge on the panel, but I guess anything's possible!
cvairwerks
Staff Sergeant
Nope. total dynamic pressure. We use vane assemblies that gear drive a set of synchros to get yaw and pitch data.
Here's a quick video where you can see the van assemblies in action. The noseboom with the vanes can bee seen at the bottom, center of the video. CAUTION....IF you suffer from vertigo or motion sickness easily, watch at your own risk.
I fully agree. If you take a close look you can see that the pitot tube and ring has a cardanic joint to the boom. By this you can measure the angular difference between aircraft axis and free straight airflow.
To measure total dynamic pressure is the job of the front opening of the pitot tube only.
I suspect its a Directional Airspeed probe - see here for example:
Rochester Avionics Archive
rochesteravionicarchives.co.uk
cvairwerks
Staff Sergeant
Yep, and in many instances, the control engineers want the data from the probe to be in the direction of flight, no matter what the yaw and pitch component are at the time of the measurement. Hence, the swivel head probe was developed for low speed test work. In the case of our nosebooms on the the F-16, F-111 and F-22, we have the vane assemblies to supply pitch and yaw data, along with a total temp probe that allowed us to get the pressure and correct for the yaw and pitch and not need a swivel head probe. All of our noseboom designs went thru an initial wind tunnel calibration procedure to get the required correction coefficients long before the first ones were flown.
davparlr
Senior Master Sergeant
It looks like a venturi design which would really screw up the air velocity and pressure. I think it is the carburetor that runs the pitot tube!! 
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- #14
All I can say is "wow!" I looked everywhere (I thought) but totally missed anything like this. Thanks so much!
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- #15
chipieal
Airman
I am sure this is not the case. However, this looks suspiciously like the gunsite hood and fender ornaments used on mid 50's Buicks. Was the company that produced these a subsidiary of General Motors? Remember the tailfin on a 48 Cadillac was inspired by the tail boom of a P- 38 Lightning.
SaparotRob
Unter Gemeine Geschwader Murmeltier XIII
I think you're on to something. That probe shape looked familiar.
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- #18
That brings back memories of my youth, washing and polishing the family car in the days of airplane hood decorations and gunsight fender ornaments!
cvairwerks
Staff Sergeant
The Meggitt HADS....
Had to do a little reading for the answer, as I wasn't a helo flight test guy, but the ringed fin units are designed to be within the rotor downwash and give accurate pointing with the helo in motion. It operates like the seeker heads on GBU kits and aligns the probe with the actual direction of flight, within it's limits.
Had to do a little reading for the answer, as I wasn't a helo flight test guy, but the ringed fin units are designed to be within the rotor downwash and give accurate pointing with the helo in motion. It operates like the seeker heads on GBU kits and aligns the probe with the actual direction of flight, within it's limits.
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