# Poor Boy Airspeed Indicator

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#### Aviator168

##### Well-Known Member
The problem with a number of this class of instruments is that they are made primarily for ultralights and hang gliders. Their air speed and altitude are somewhat limited. What is needed is something for the smaller LSA planes. When you get to the larger LSA, the builder will most likely go with standard instruments, but if you are trying to build a smaller LSA for under $10,000---I don't know about the rest of you, but I am hesitant to put 10% of that into just the instruments. Not to mention the limited panel space for using the 3 1/8 inch gauges. People can build a large LSA for less than$30k (no engine, no gauges). A glass panel will cost your more than 15% also. The only thing home built glass panels don't have is a high intensity display. May be I should start building mine while designing my UL. I would also like to have a few real steam gauges.

##### Well-Known Member
Really?!? Can you provide a source for this? I find that very, very hard to believe even if that's a price per sensor. Remember flight instrument six-pack is defined included airspeed indicator, attitude indicator, altimeter, turn coordinator, heading indicator and vertical speed indicator. Personally, I'd be happy if it were that simple and easy and inexpensive to get just a minimum VFR package like airspeed, altimeter, compass, tachometer, fuel gauge and oil pressure/temperature.
I have about $150 in parts to get to a six pack with an Arduino and an LED display. All the information will be in text form and I won't display attitude or turn coordinator but the data is there to do so with a more expensive display and more programming effort. #### nerobro ##### Well-Known Member Log Member I have about$150 in parts to get to a six pack with an Arduino and an LED display. All the information will be in text form and I won't display attitude or turn coordinator but the data is there to do so with a more expensive display and more programming effort.
I'm looking at doing the same thing. I've got a few pressure sensors and some solid state gyros.

But here's the important part. Your brain doesn't handle "numbers" very well. That's where steam guages rock. The moving needle is the big deal there. ... Getting a moving needle is easy. Arduino can output pwm to a servo, and you put the servo behind a guage face. By default you get around 180deg of needle sweep. If you need mulitple turns you can use a gearbox, or a sail servo. Servos behind glass are a lot lighter than steam guages anyway.

#### Aviator168

##### Well-Known Member
FYI. Be careful about solid state gyros. Some of them are not gyros; they are just accelerometers. You will notice if place them at level position, their readings will change when rapidly moved to one side without rotation. There are micro gyros you can buy (something actually spins). Not expensive at all.

#### bmcj

##### Well-Known Member
HBA Supporter
FYI. Be careful about solid state gyros. Some of them are not gyros; they are just accelerometers. You will notice if place them at level position, their readings will change when rapidly moved to one side without rotation. There are micro gyros you can buy (something actually spins). Not expensive at all.
Excellent point. As a good example, the ill-fated Air Forcd CT-43 that crashed in Croatia with Secretary of Commerce Ron Brown aboard was found to have been the victim of inertial navigation error. The flight was at night in bad weather on approach to Dubrovnich. The Airport there didn't have the required nav systems working, so the pilots switched to inertial. The error that Aviator168 mentions led to CFIT.

#### Aviator168

These days. $150 can buy you a laser ring gyro. If your life depends on it, won't hurt to spend a few more dollars. the ill-fated Air Forcd CT-43 that crashed in Croatia with Secretary of Commerce Ron Brown aboard was found to have been the victim of inertial navigation error How do you know that? A black box was not installed on that plane. #### Pops ##### Well-Known Member Log Member These days.$150 can buy you a laser ring gyro. If your life depends on it, won't hurt to spend a few more dollars.
View attachment 30761

How do you know that? A black box was not installed on that plane.[/COLOR]
That's a great one. Looks like it cheaper that it was a short time back. Dan

Log Member

#### Aviator168

##### Well-Known Member
Current MEMS gyros are good enough; but you do have to evaluate them before using on your aircraft. Still, ring laser gyros are the most accurate. Now, if you use laser accelerometers for distance calculation, you can even say good bye to the GPS.

#### jedi

##### Well-Known Member
I do like to have a torque meter between the engine and the prop. It is expensive indeed........
Don't need it between the engine and prop on rotating components that make a lot of signal noise. Strain gage the engine mount (or motor mounts) to get your torque. Getting good sensativity is the issue.

#### Aviator168

##### Well-Known Member
Don't need it between the engine and prop on rotating components that make a lot of signal noise. Strain gage the engine mount (or motor mounts) to get your torque. Getting good sensativity is the issue.
Good idea. The torque is probably the best way get the power output.