CWAM at the Corsicana Airshow, Part 1

The Cold War Air Museum gets a fun opportunity to participate in the Corsicana Airshow every year.

The crowds enjoyed seeing our aircraft as well as a great many others.

Big kids and little kids are always fascinated to see flying machines, especially the Mi-24.

With the B-17 flying overhead and lots of other activities, there was plenty to see, hear and do.

Including getting your picture taken by our friendly guys.

The L-39 was a hit as well. With the price of fuel being what it is today, it is more of a burden for turbine aircraft owners to attend shows.

Old and new, a view of the B-17 on approach from the L-39 rear seat.

Thanks to Andy Nixon for sharing these fun photos with us. We'll have more soon in Part 2 of this series.

At the Cold War Air Museum - 14 May, 2011

Every weekend seems full of activity at the Cold War Air Museum. With an Airshow at Corsicana, Texas (KCRS) and visitors on the way to our Airport (KLNC), the day was loaded for work and fun.

With the Big Bird going to the show, Johnny was out early getting things ready.

All set, Johnny leads off in the Mi-2.

The faster Mi-24 soon followed with Coz at the controls. Andy Nixon joined us for the flight and we are looking forward to posting his pictures from the show soon.

And with the shortest flight time of all, Jon soon joined the others on the ground.

Not to be outdone by Corsicana, there was still plenty of activity at the home field.

With the establishment of an aerobatic box next to the airport, there is often additional activity like there was today.

A number of QB's and other visitors stopped by to enjoy the good weather and good company. We appreciate the visitors and donations received today.

Jan Collmer and his beautiful Extra 300, were among those welcomed.

And one of the other L-29's based at the field took advantage of the weather and good company to get out and get some exercise. There are few L-29's with better paint or detail than this one.

Of course, pretty planes attract pretty women. Dressed for a party they were attending later, these young ladies paused long enough to get their picture in today's post.

Just another beautiful day in Texas with great aircraft, great folks and great fun. Thank y'all and please come back again.

L-39 Formation Video

Associates of the Cold War Air Museum enjoy getting together to fly their aircraft. It's a special treat when our friend Scott comes along and shares his videos with the blog.

Bord 107 plays to the camera during formation practice.



And makes a nice roll-off.



Thanks Scott! We are hoping to be able to schedule a formation clinic with our friends at the Red Star Pilot's Association soon. Stay tuned for further information

A Cold *REALLY* Cold War Air Museum Day

Texas has mostly good, temperate weather throughout the year (and lots of flat empty land). For that reason, many bases and flight schools were located here during the cold war years. Sometimes however we have a cold spell. Last Saturday the weather got down into the teens (-10c).

Although we had planned to fly several aircraft to another airport, the event was canceled because the kids (and adults) at the other airport proclaimed it to be "too cold" to look at cold war aircraft. We were happy to reschedule the flight for warmer weather and happy that we have other aircraft on display indoors at the Cold War Air Museum. Since the aircraft were out and ready to go, we made some local flights with those that braved the cold of the day.

Jon showed up early to get the L-39 ready.
Any excuse for Jon to wear his Ushanka hat is a good excuse for Jon.

Tracey, a multi-engine, instrument rated commercial pilot, flew with Jon. Her boots were a hit and complimented her ZSH-7 Helmet (and Jon's hat).

On cold days, there is a noticeable increase in the jet's performance.

The Mi-2 also flew.

Our friend Miguel took pictures on this (Cold) Cold War Air Museum day. To see more of his photos, visit his Flikr page.

- A day in cold war history -
January 14th

The first flight of the MiG-17 (Микоян и Гуревич МиГ-17) occurred on 14 January, 1950. The design was a direct descendant of the MiG-15 and direct predecessor to the MiG-21, MiG-23 series. Worldwide production exceeded 10,000. Originally a cannon equipped day fighter, it was replaced by supersonic, all weather aircraft.

Aero Vodochody L-39 - Wash, Rinse, Repeat

A recent series of posts (select label "hot wash") on the Cold War Air Museum Blog has been about cleaning the turbine blades on L-39 Bord 107 to lower the engine peak temperature.


We're happy to report that Jon's temperature is now down to 660. Well, actually that's not Jon's temperature, that is his airplane's engine temperature. Even though some of his admirers think Jon is hot, it would be bad if he were that hot, especially since the temperature we are talking about is in Centigrade (Oops, that's Celsius for those of you born in the last half century).

We received a lot of assistance from people telling us how to perform the procedure and we want to thank everyone that contributed! The spray rig Jon made is on the maintenance ladder. A water jug fits perfectly on a drain below the aircraft. How or why they designed for this, we don't understand. But, as our local resident formerly of the Czech Republic likes to say (repeatedly), "Czechs, are very clever people".

Jon checks the patient's output. As 107 came clean, the specimen became progressively clearer.

Hot Wash Sprayer

Prop wash, Jet wash, Hot Section Wash. Only one has something to do with a bath. In a previous maintenance post, Jon talked about his work chasing rising temperature indications in our Cold War Air Museum, L-39, Bord 107.

Another step in the maintenance process involves washing the engine with a special cleaning solution while it is running. Essentially this gives the guts of the engine a bath, helping to clean out any accumulated gunk interfering with the combustion process.

After receiving diagrams and information from a former Eastern Bloc specialist, Jon fabricated a high volume, high pressure spray unit to inject the cleaning solution into an intermediate stage of the engine at high power. With the help of our local network of scroungers and specialists (not to be confused with scoundrels and speculators), Jon created this unit to deliver the pressure and volume specified.

To test the unit we timed the required delivery of the required volume of fluid. The test went exceedingly well.

Jon demonstrates the cleaning solution delivery system by a emulating a boy in a European fountain (well, he sorta kinda had that Greek/Roman statue look anyway).

Before the wash procedure, copious quantities of distilled water were acquired to mix with the cleaning solution.

Hot, Hot, Hot

One of the museum's L-39s, Bord 107, has been running high EGT (exhaust gas temperature) for some time. The L-39 has an EGT limiting circuit that illuminates a warning light at 700°C... and should the EGT reach 730°C in flight, the engine will automatically be shut down when the nose-wheel touches the ground. (No go-arounds possible!)

A "730" event is very serious in nature and requires an inspection to be performed before the secret reset button (location not divulged to pilots) is pressed and the engine can be started again.

Bord 107 was regularly seeing the 700°C light flash on take-off and the situation was mitigated by pulling the throttle back a bit. But too much of that and the turbine will start spitting blades out the back.

Soot buildup in the combustion chambers eventually disturbs the flame pattern, causing the combustion to continue as it moves further back. Flames licking at the EGT probes behind the engine gets the warning light to start screaming, "Ow! You're hurting me!"

Over time the ventilation holes in the inner jacket get, as our very German adviser says, "stuffed like little bratwurst". Lack of good air flow prevents a good clean burning of the fuel.



The problem initially manifested itself as a drop in the HPC (high pressure compressor) RPM. Our Czech mechanic had adjusted the fuel controller to put a little more fuel in to bring the RPM back up. That brought the RPM back up, but the EGT came up with it... in effect, it only made the problem worse since extra fuel burned even longer and even farther back in the compressor area.

One indication of this problem is flames in the exhaust at high power. Our adviser, Bernd of Aero Contact, sent these graphics to illustrate what to look for:


Taking a look at Bord 107, that's what we saw — and Brad has a whole new respect for jet exhaust! Fortunately, there is a solution, although not a simple one.

The first step was to send all the instruments to Bernd in Germany to have them inspected and calibrated; it simply wouldn't be possible to get to a "correct" solution without accurate readings on the instruments.

So out they came...


And off they went...


After Aero Contact's analysis, the instruments were judged to be in tolerance, although the front and rear RPM indicators need to be swapped so that the more accurate one would be in the front cockpit.

Historically there have been a number of ways to deal with soot buildup in jet engines. One of the simplest ways to clean an engine is to fly through heavy rain. The scrubbing effect of the water and steam will do wonders for a mildly dirty engine. Rain water has the added benefit of having a very low mineral content, so it's much better for the engine than tap water. Another simple method was to bring the engine up to speed and throw a small amount of ground Walnut shells (yes, WALNUT SHELLS) into the engine. While this worked reasonably well for centrifical flow engines, it doesn't work quite as well for axial flow engines... and a hard chunk of walnut shell can do more harm than good.

The more modern method is to spray a solvent into the engine in one of two methods, either OFF-LINE or ON-LINE. Off-line (or "crank washing") an engine consists of "cold" rotating the engine at 20-25% RPM and soaking it down with solvent. On-line washing injects the solvent while the engine is actually running at about 90%. Using both methods together generally results in a good cleaning.

Caustic solvents were originally the preferred detergent for cleaning engines, but they were an EPA nightmare. A lot of chemical engineering has gone into producing water-based solvents such as TurboTect 2020 that are almost as effective as the old solvents and the effluent doesn't have to be carted off in a HazMat truck. The water-based solvents do a little better job on hardened salts but not quite as good a job on small (35 micron or smaller) particulates. A number of patents have been issued in recent years for solutions to this problem.

Bernd is sending a special injection tool to do crank washing deep within the compressor section. A few cycles of this kind of cleaning will reportedly bring the EGT down as much as 40°C and improve the power output by several percent.

The instruments, injection tool and a 55 gallon drum of solvent should all be here this week... and none too soon, it's hot enough in Texas!

L39 Swap out

In a previous story, we posted that the museum's L-39s were getting condition inspections.

This inspection, which must be made once every 12 months when the aircraft is flying, was completed on Bord 107. So it started on its way back to its normal hanger.

Now its Bord 909's turn for some attention in the maintenance hanger.

Its that time of year again, L39 Annuals

Every year our flying aircraft get a condition inspection.
L39, Bord 107 is being moved into the maintenance hanger for this annual event. Bord 25 can be seen in the background. It has been moved out to make room and will be stored temporarily in another hanger.

We took the opportunity to clean and straighten the work area while the aircraft were being moved. In addition to other work, the aircraft will be placed on jacks and hooked to an external hydraulic mule so gear and system checks can be run.

Bord 25, seen past the noses of the Mig21 and L39 will have an engine test run while it is outside to keep its conservation up to date.



Jon supervises students and volunteers as they set up the jacks under the aircraft. The jacks contain a level and should be set precisely vertical before use. our student volunteers are from the Dallas School District Aviation program at Skyline High School.